ARTICLE | doi:10.20944/preprints202202.0160.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: membrane pump theory; membrane potential; diffusion; Biophysics; Biology
Online: 11 February 2022 (10:27:36 CET)
The generation and maintenance of membrane potential is a fundamental part of Membrane Pump Theory. One of the key points of this hypothesis is based on a natural or facilitated molecular diffusion through several types of ion channels and pumps like the Na/K ATPase. Chemistry, physics and especially electrochemistry, however, bring strong contradictions to this theoretical assumption. By respecting the principles of chemistry and electrostatics, it becomes obvious that this theoretical hypothesis cannot work. The ionic diffusion that would be at the origin of this potential cannot take place. Indeed, the topology and the forces involved definitively exclude the current model, which must absolutely be revised according to the current state of our knowledge and allow an advance in the understanding of the phenomena and open new research perspectives.
ARTICLE | doi:10.20944/preprints202310.0840.v1
Subject: Biology And Life Sciences, Biophysics Keywords: membrane pump theory; membrane potential; mathematics; Biophysics; Biology
Online: 13 October 2023 (16:43:12 CEST)
The generation and maintenance of membrane potential is considered a fundamental element of the cellular machinery. They are based on elements of physics and chemistry. Mathematics is used to validate the equations and evaluate the results. However, this computation process can lead to a misunderstanding of the phenomena involved or to the masking of crucial events. It is even possible that the calculation no longer corresponds to the hypothesis considered. Membrane theory is no exception to these trivial considerations, which are essential for normal theory validation.
ARTICLE | doi:10.20944/preprints202309.1758.v1
Subject: Biology And Life Sciences, Life Sciences Keywords: membrane pump theory; membrane potential; cell shape; biophysics; biology
Online: 26 September 2023 (11:32:12 CEST)
Membrane potential generation and maintenance are fundamental parts of membrane theory. However, since its inception, theories and assumptions have remained simple, whereas the amount of knowledge available has only grown. Unfortunately, this simplification and reductionism lead to its loss of validity on both microscopic and macroscopic scales. This article shows that assumptions made outside the context of factual reality lead to contradictions that cannot be compared with science. Membrane theory must be thoroughly revised, taking into account all forgotten and unanswered assumptions and questions to conform to facts and science to maintain credibility.
ARTICLE | doi:10.20944/preprints202204.0230.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: membrane pump theory; membrane potential; ion channel; Na/K ATPase; thermodynamics; elecrtromagnetism
Online: 26 April 2022 (06:11:34 CEST)
The membrane potential or resting potential of the neuron has been the subject of many studies. Although this theory explains the generation and maintenance of the membrane potential by direct or even facilitated diffusion, there are too many contradictions to doubt that these forces are sufficient or even at work in a process whose initial conditions are of rare complexity. The aim of this article is to show that already in the past, a competing theory has been developed whose hypothesis seems more scientifically sound. To confirm this last theory, Hirohisa Tamagawa carried out an experiment of great simplicity which makes it possible to invalidate the current theory and to question the teaching and the knowledge in Biology and Biophysics.
ARTICLE | doi:10.20944/preprints202204.0182.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: membrane pump theory; membrane potential; ion channel; NA/K ATPase; Biophysics; Biology
Online: 20 April 2022 (03:42:28 CEST)
The generation and maintenance of membrane potential is a fundamental part of Membrane Pump Theory. One of the key points of this hypothesis is based on a natural or facilitated molecular diffusion through several types of ion channels and pumps like the Na/K ATPase. Following the principles of chemistry, electrostatics and geometry, it becomes clear that ion channels cannot function in this way. The ions channels cannot by their location have both a filter function and be ion concentrators, and the Na/K pump by its position in the membrane and by the proposed assumptions is not able to perform its regulatory function. The current model must absolutely be revised according to the current state of our knowledge and allow an advance in the understanding of the phenomena opening new research perspectives.
ARTICLE | doi:10.20944/preprints202208.0510.v1
Subject: Biology And Life Sciences, Anatomy And Physiology Keywords: membrane potential; water; adsorption; structured water
Online: 30 August 2022 (06:00:56 CEST)
The occurrence of potential spikes in a cell is a sign of life, and it is called action potential. There is a common notion that neuron signal conduction is the conduction of action potential. Hence, action potential is a typical and essential life activity. However, such potential spikes occur even in simple nonliving systems. According to the experimental observations by Pollack, structured water molecules can generate a negative potential environment. From this observation, the potential spike generation process for both living and nonliving systems caused by ion and water molecule adsorption-desorption process could be explained in this paper. So, taking into consideration the electrically neutral water molecules,the action potential generation mechanism could be explained. It is a fully inanimate model. Hence, the action potential may not be a life activity. Here, the role of water molecules in life is investigated further. It was found that the phase transition of the membrane is involved in the neuron signal conduction, but the membrane phase transition could be due to the change of state of the water molecules, which forms a large-scale structure in the cavities created by a number of lipids.
ARTICLE | doi:10.20944/preprints202205.0200.v1
Subject: Biology And Life Sciences, Biophysics Keywords: membrane potential; Nernst equation; ion adsorption; surface charge; surface potential
Online: 16 May 2022 (08:12:52 CEST)
Although there is a common physiological notion that the origin of the membrane potential is attributed to transmembrane ion transport, it is theoretically possible to explain its generation by the mechanism of ion adsorption. It was previously suggested that the ion adsorption mechanism led even to the potential formulas which are even identical to either the famous Nernst equation or Goldman-Hodgkin-Katz equation. Our further analysis shown in this paper indicates that the potential formula based on the ion adsorption mechanism leads to one equation which is the function of material surface charge density and the material surface potential. Furthermore, we confirmed that the equation holds in all the different experimental systems we studied. Although we have not succeeded in elucidating why such an equation is established, the equation appears to be the key equation governing the characteristics of the membrane potential regardless of the systems in question.
ARTICLE | doi:10.20944/preprints202311.0711.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: antifungal potential; naphthoquinone derivatives; 2,3-DBNQ; fungal membrane permeability; cytotoxicity
Online: 13 November 2023 (08:25:22 CET)
The increase in fungal infections, accompanied by adverse effects and acquired resistance associated with the use of antifungal agents used for their clinical management, have facilitated the search for new substances with antifungal properties. Naphthoquinones have been investigated due to their multiple biological activities, including their significant antifungal potential. This study aimed at evaluating the antifungal potential of naphthoquinones against opportunistic fungi and dermatophytes and to assess the impact of a selected naphthoquinone on the formation of the cell wall, ergosterol membrane, and cellular membrane of Candida albicans ATCC 60193. Additionally, cytotoxicity in the MRC-(Medical Research Council-)5 cell lineage, Artemia salina, and tomato as well as arugula seeds was evaluated. The antifungal activity of four naphthoquinones was assessed using well-characterized fungal strains, the minimum inhibitory concentration (MIC) was determined applying the microdilution assay technique. Antifungal activity of the assessed naphthoquinones could be confirmed, particularly for 2,3-DBNQ (2,3-dibromo-1,4-naphthoquinone), which showed prominent antifungal activity (MIC of <1.56 - 6.25 µg/mL) in all chosen test settings. However, its toxicity in MRC-5 cells (IC50 = 15.44 µM), a recorded 100% mortality in A. salina at a concentration of 50 µg/mL, as well as inhibition of 94.8% of the tomato seeds at a concentration of 400 µg/mL and inhibition of 64.1% of arugula seeds at a concentration of 200 µg/mL may limit hypothetical therapeutic applications. It was demonstrated that the likely mechanism of action of 2,3-DBNQ involves interfering with fungal membrane permeability, leading to increased leakage of nucleotides. This study adds to available knowledge on antifungal effects of naphthoquinones, especially of 2,3-DBNQ, against opportunistic yeasts and dermatophytes. However, the observed cytotoxicity in the MRC-5 cell lineage, A. salina, as well as tomato and arugula seeds highlights a need for further research to optimize the selectivity and safety profile of naphthoquinones like 2,3-DBNQ before potential clinical use may be assessed.
ARTICLE | doi:10.20944/preprints202012.0432.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: pomegranate; antioxidant capacity; membrane vesicles; cauliflower; keratinocytes; oxidative stress; cytotoxicity
Online: 17 December 2020 (12:05:42 CET)
Pomegranate extract (PG-E) has been reported to exert a protective effect in skin due to its antioxidant activity. Ingredients rich in phenolic compounds are unstable in extract solutions and, therefore, the use of a suitable nanosystem to encapsulate this type of extract could be necessary in different biotechnological applications. Thus, we investigated the capacity of Brassica oleracea L. (cauliflower) inflorescence vesicles (CI-vesicles) to encapsulate PG-E and determined the stability and the antioxidant capacity of the system over time. In addition, the protective effect against UV radiation and heavy metals in HaCaT cells was also tested. The CI-vesicles had an entrapment efficiency around 50% and accelerated stability tests did not show significant changes in the parameters tested. The results for the HaCaT cells show the non-cytotoxicity of the CI-vesicles containing PG-E and their protection against heavy metals (lead acetate and mercuric chloride) and UV-B radiation through a reduction of oxidative stress. The reduction of the percentage of deleted mtDNA (mtDNA4977, “common deletion”) in UV-treated HaCaT cells due to the presence of CI-vesicles containing PG-E indicates the mechanism of protection. Therefore, the effects of CI-vesicles loaded with PG-E against oxidative stress support their utilization as natural cosmeceuticals to protect skin health against external damage from environmental pollution and UV radiation.
REVIEW | doi:10.20944/preprints202306.1948.v1
Subject: Biology And Life Sciences, Aging Keywords: Aging, mitochondria, membrane potential, permeability transition pore, C. elegans
Online: 28 June 2023 (07:06:20 CEST)
It is widely reported that the mitochondrial membrane potential, ∆Ψm, is reduced in aging animals. It was recently suggested that the lower ∆Ψm in aged animals modulate mitochondrial bioenergetics and that this effect is a major cause of aging since artificially increased ∆Ψm in C. elegans increased lifespan. Here I review, critically, studies that reported reduction of ∆Ψm in aged animals, including worms, and conclude that many of these observations are best interpreted as evidence that the fraction of depolarized mitochondria is increased in aged cells because of the enhanced activation of the mitochondrial Permeability Transition Pore, mPTP. Activation of the voltage-gated mPTP depolarizes the mitochondria, inhibits oxidative phosphorylation, releases large amounts of calcium and mROS, and depletes cellular NAD+, thus accelerating degenerative diseases and aging. Since the inhibition of mPTP was shown to restore ∆Ψm and retard aging, the reported lifespan extension by artificially generated ∆Ψm in C. elegans is best explained by inhibition of the voltage-gated mPTP. Similarly, the reported activation of the mitochondrial Unfolded Protein Response by reduction of ∆Ψm, and the reported preservation of ∆Ψm in dietary restriction treatment in C. elegans are best explained as a resulting from activation or inhibition of the voltage-gated mPTP, respectively.
REVIEW | doi:10.20944/preprints202306.0462.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: membrane hyperpolarization; SLO3; contraception; potassium channels; sperm; acrosomal exocytosis; capacitation; hyperactivated motility; SLO channels; male fertility
Online: 6 June 2023 (14:01:18 CEST)
Sperm cells must undergo a complex maturation process after ejaculation to be able to fertilize an egg. One component of this maturation is hyperpolarization of the membrane potential to a more negative value. The ion channel responsible for this hyperpolarization, SLO3, was first cloned in 1998, and since then much progress has been made to determine how the channel is regulated and how its function intertwines with various signaling pathways involved in sperm maturation. Although SLO3 was originally thought to be present only in the sperm of mammals, recent evidence suggests that a primordial form of the gene is more widely expressed in some fish species. As with many reproductive genes, SLO3 is rapidly evolving with low conservation between closely related species and different regulatory and pharmacological profiles. Despite these differences, SLO3 appears to have a conserved role in regulating sperm membrane potential and driving large changes in response to stimuli. As with the differences in regulation of the channel, the effect of this hyperpolarization of the membrane potential may vary among mammalian species. Recent discoveries have elucidated the role of SLO3 in these processes in human sperm and provided tools to target the channel to affect human fertility.
ARTICLE | doi:10.20944/preprints201903.0227.v2
Subject: Biology And Life Sciences, Horticulture Keywords: oxidative stress; enzymatic antioxidants; malondialdehyde; membrane permeability; chlorophyll
Online: 28 March 2019 (11:15:50 CET)
Scarcity of water is one of the most serious concerns in plant biology with diverse implications at all the levels of molecular, biochemical, and physiological phenomena of plant growth, development, and consequently the productivity. Most of the strategies to induce or enhance drought tolerance in plants are unreasonably expensive and/or time-consuming. Some studies conducted in the recent past have shown that plant growth regulators (PGRs) may induce/improve physiological tolerance in plants to cope with adverse environmental conditions including drought. The present study was aimed at investigating the effects of foliar spray of GABA (0, 1, 2, and 4 mM) applied 20 days following the germination of seeds, on vegetative growth, morphological characteristics, integrity of cell-membrane, and the levels of photosynthetic pigments and enzymatic antioxidants in carrot cvs. Supertaj and Bharat, grown under 100% and 50% field capacity of soil moisture. The treated and untreated (control) carrot plants were harvested and analyzed 2 weeks following the GABA application. The results revealed that foliar application of GABA improved the vegetative growth and significantly increased the levels of free amino acids, plastid pigments, enzymatic antioxidants, and the relative water content in the root crop grown under 50% field capacity of soil moisture, compared to control. Additionally, the GABA application decreased the electrolyte leakage of ions and melondialdehyde (MDA) content in carrot leaves. The carrots harvested from GABA-treated or untreated (control) plants were not significantly different for their protein contents. In conclusion, the incorporation of GABA in the production management of carrots may help plants to mitigate the adverse effects of water deficit stress.
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: membrane remodeling; membrane biosynthesis; membrane curvature; phospholipids; inner membrane; lipid biosynthesis
Online: 25 August 2020 (10:03:25 CEST)
Membrane remodeling and phospholipid biosynthesis are normally tightly regulated to maintain the shape and function of cells. Indeed, different physiological mechanisms ensure a precise coordination between de novo phospholipid biosynthesis and modulation of membrane morphology. Interestingly, the overproduction of certain membrane proteins hijack these regulation networks, leading to the formation of impressive intracellular membrane structures in both prokaryotic and eukaryotic cells. The proteins triggering an abnormal accumulation of membrane structures inside the cells (or membrane proliferation) share two major common features: 1) they promote the formation of highly curved membrane domains and 2) they lead to an enrichment in anionic, cone-shaped phospholipids (cardiolipin or phosphatidic acid) in the newly formed membranes. Taking into account the available examples of membrane proliferation upon protein overproduction, together with the latest biochemical, biophysical and structural data, we explore the relationship between protein synthesis and membrane biogenesis. We propose a mechanism for the formation of these non-physiological intracellular membranes that shares similarities with natural inner membrane structures found in α-proteobacteria, mitochondria and some viruses-infected cells, pointing towards a conserved feature through evolution. We hope that the information discussed in this review will give a better grasp of the biophysical mechanisms behind physiological and induced intracellular membrane proliferation, and inspire new applications, either for academia (high-yield membrane protein production and nanovesicle production) or industry (biofuel production and vaccine preparation).
ARTICLE | doi:10.20944/preprints202009.0325.v1
Subject: Chemistry And Materials Science, Electrochemistry Keywords: Keywords; CO2; conversion; bibliometrics; electrode design; CO2RR; membrane; flow cell
Online: 15 September 2020 (04:45:17 CEST)
The chemistry and electrochemistry basic fields have been active since the last two decades of the past century studying how surface modification of electrodes by coating with conductive films enhances their activity and performance. In the light of the development of alternative sustainable ways of energy storage and carbon dioxide conversion by electrochemical processes, these research studies have jumped in the 21st century to more applied fields such as chemical engineering, energy and environmental science and engineering. The huge amount of literature on experimental works dealing with the development of CO2 electroreduction processes addresses electrocatalyst development. Membranes can help understanding and controlling the mass transport limitations of current electrodes and reactors designs. The present bibliometric review addresses the papers published in the 21st century regarding membrane coated electrodes and electrocatalysts to enhance electrochemical reactor performance and viability with a special focus on the urgent issue of carbon dioxide capture and utilization.
REVIEW | doi:10.20944/preprints202208.0248.v1
Subject: Biology And Life Sciences, Anatomy And Physiology Keywords: action potential; soliton/wave; lipid phase transition; scientific method; membrane
Online: 15 August 2022 (04:27:26 CEST)
This article is a followup to an earlier review which outlined some of the interesting features of the soliton/wave-action potential (AP) model, and noted the need to test its key aspects; including the need to test if its presumed lipid phase transition is actually happening during AP firings in excitable cells. The intent here is to point out the sort of tests, and evidence from them, that might be needed if the soliton/wave-AP model is to be accepted broadly by biologists. Here, after an overview of the modern electrophysiological-AP model and of the soliton/wave-AP model, there are three areas considered. First, possible compositional influences on membrane properties relative to the soliton/wave-AP model are presented. Including questions with regard to the soliton/wave-AP model’s assumption that changes in surface potentials influence the transmembrane potential. Second, some recent work from the good folks who advocate for the soliton/wave-AP model concerning the occurrence of lipid phase transitions in neurons or in extracts from nervous tissues are examined. Here it is noted that there is a need to consider whether these lipid phase transitions happen within normal physiological conditions or not. Third, and finally, the advocates for the soliton/wave-AP model have adopted a thermodynamic/theory-based philosophical approach in their studies. It is argued that this philosophical approach is a radical departure from the philosophical approach used under the scientific method. The features of this new approach, and implications its use, are examined.
ARTICLE | doi:10.20944/preprints201804.0141.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: scrub typhus; Orientia tsutsugamushi; Rickettsia; Rickettsiales; outer membrane protein A; Anaplasma
Online: 11 April 2018 (08:13:04 CEST)
Scrub typhus threatens one billion people in the Asia-Pacific area and cases have emerged outside this region. It is caused by infection with any of the multitude of strains of the bacterium, Orientia tsutsugamushi. A vaccine that affords heterologous protection and a commercially available molecular diagnostic assay are lacking. Herein, we determined that the nucleotide and translated amino acid sequences of outer membrane protein A (OmpA) are highly conserved among 51 O. tsutsugamushi isolates. Molecular modeling revealed the predicted tertiary structure of O. tsutsugamushi OmpA to be very similar to that of the phylogenetically related pathogen, Anaplasma phagocytophilum, including the location of a helix that contains residues functionally essential for A. phagocytophilum infection. PCR primers were developed that amplified ompA DNA from all O. tsutsugamushi strains, but not from negative control bacteria. Using these primers in quantitative real-time PCR enabled sensitive detection and quantitation of O. tsutsugamushi ompA DNA from organs of mice that had been experimentally infected with the Karp or Gilliam strains. The high degree of OmpA conservation among O. tsutsugamushi strains evidences its potential to serve as a molecular diagnostic target and justifies its consideration as a candidate for developing a broadly protective scrub typhus vaccine.
REVIEW | doi:10.20944/preprints202111.0190.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: Malaria; proteases; Plasmodium rhomboids; dipeptidyl aminopeptidases; apical membrane antigen; subtilisin-like proteins; glucose transporters; schizogony; plasmepsins
Online: 9 November 2021 (15:50:12 CET)
There is an overarching need to find alternative treatment options for malaria and this quest is more pressing in current times due to the morbidity and mortality data arising from most endemic countries and partially owing to the fact that the SARS-Cov-2 pandemic has diverted much public health attention. Additionally, the therapeutic options available for malaria has been severely threatened with the emergence of resistance to almost all existing drugs by the human malaria parasite. The Artemisinin Combination Therapies (ACTs) which hitherto have been the mainstay for malaria have encountered resistance in South East Asia, a notorious ground zero for the emergence of antimalarial drug resistance. This review analyses few key druggable targets of the parasite and the potential to leverage strategic inhibitors to mitigate the scourge of malaria by providing a concise assessment of the essential proteins of the malaria parasite that could serve as targets. Furthermore, this work provides a summary of the advances made in malaria parasite biology and the potential to leverage such findings for antimalarial drug production.
ARTICLE | doi:10.20944/preprints202002.0041.v1
Subject: Medicine And Pharmacology, Pharmacology And Toxicology Keywords: geranylgeranyl acetone (GGA); heat shock proteins (Hsps); HT-22 (hippocampal neuronal) cells; mitochondrial membrane potentials
Online: 4 February 2020 (10:24:57 CET)
Geranylgeranyl acetone (GGA) protects against various types of cell damages by upregulating heat shock proteins. We investigated whether GGA protect neuronal cells from cell death induced by oxidative stress. Glutamate exposure was lethal to HT-22 cells which comprise a neuronal line derived from mouse hippocampus. This configuration is often used as a model for hippocampus neurodegeneration in vitro. In the present study, GGA protected HT-22 cells from glutamate-induced oxidative stress. GGA pretreatment did not induce Hsps. Moreover, reactive oxygen species increased to the same extent in both GGA-pretreated and untreated cells exposed to glutamate. In contrast, glutamate exposure and GGA pretreatment increased mitochondrial membrane potential. However, increases in intracellular Ca2+ concentration were inhibited by GGA pretreatment. In addition, the increase of phosphorylated ERKs by the glutamate exposure was inhibited by GGA pretreatment. These findings suggest that GGA protects HT-22 cells from glutamate-provoked cell death without Hsp induction and that the mitochondrial calcium buffering capacity plays an important role in this protective effect.
ARTICLE | doi:10.20944/preprints202103.0079.v1
Subject: Physical Sciences, Acoustics Keywords: Bacteria; elasto-inertial focusing; microfluidics; microwaves; membrane potential; sensing; shear stress; single cell detection; system-on-a-chip
Online: 2 March 2021 (11:24:18 CET)
The investigation of the electromagnetic properties of biological particles in microfluidic platforms may enable wireless monitoring and interaction with functional activity of microorganisms. Of high relevance is the membrane potential as it is one of the most important parameters of living cells. In particular, the complex mechanisms of the cell’s membrane potential are comparable to the dynamics of bacteria membranes, providing a simplified platform for advancing the current techniques and knowledge of general bio-particle dynamics. In this work, we provide a theoretical analysis and experimental results on the microwave detection of bacteria on a microfluidic-based framework for sensing the membrane potential of bacteria. The results enable to further advance the state-of-the-art of electromagnetic bacteria sensing and microfluidic control, and their implication for measuring and interacting with the cell and its membrane potentials, which is of great importance for developing new biotechnological engineered systems and solutions.
ARTICLE | doi:10.20944/preprints202302.0182.v1
Subject: Engineering, Industrial And Manufacturing Engineering Keywords: beer dealcoholization; nanofiltration; polyelectrolyte multilayer membrane; Layer-by-Layer membrane; membrane-based food processing; membrane modification
Online: 10 February 2023 (07:17:28 CET)
Membrane-based beverage dealcoholization is a successful process for producing low- and non-alcoholic beer and represents a fast-growing industry. Polyamide NF and RO membranes are commonly applied for this process. Polyelectrolyte multilayer (PEM) NF membranes are emerging as industrially relevant species and their unique properties (usually hollow fiber geometry, high and tunable selectivity, low fouling) underlines the importance of testing them in the food industry as well. To test PEM NF membranes for beer dealcoholization, at small pilot scale we dealcoholized filtered and unfiltered lager beer with the tightest available commercial polyelectrolyte multilayer NF membrane (NX Filtration dNF40), which has a MWCO=400Da which is quite high for these purposes. Dealcoholization is possible with a reasonable flux (10 LMH) at low pressures (5-8.6 bar) with a real extract loss of 16-18% and an alcohol passage of ~100%. Inorganic salt passage is high (which is typical for PEM NF membranes), which greatly affected beer flavor. During the dealcoholization process, the membrane underwent changes which substantially increased its salt rejection values (MgSO4 passage decreased 4-fold) while permeance loss was minimal (less than 10%). According to our sensory examination, the process yielded an acceptable flavored beer which could be greatly enhanced by the addition of the lost salts and glycerol.
ARTICLE | doi:10.20944/preprints201612.0093.v1
Subject: Engineering, Chemical Engineering Keywords: membrane bioreactor (MBR); membrane fouling; hollow fiber membrane; hydrophilicity; hydrophobicity; wastewater treatment
Online: 18 December 2016 (10:04:27 CET)
We aimed to investigate the relationship between membrane material and development of membrane fouling in a membrane bioreactor (MBR) using membranes with different pore sizes and hydrophilicities. Batch filtration tests were performed using submerged single hollow fiber membrane ultrafiltration (UF) modules with different polymeric membrane materials including cellulose acetate (CA), polyethersulfone (PES), and polyvinylidene fluoride (PVDF) with activated sludge taken from a municipal wastewater treatment plant. The three UF hollow fiber membranes were prepared by a non-solvent-induced phase separation method and had similar water permeabilities and pore sizes. The results revealed that transmembrane pressure (TMP) increased more sharply for the hydrophobic PVDF membrane than for the hydrophilic CA membrane in batch filtration tests, even when membranes with similar permeabilities and pore sizes were used. PVDF hollow fiber membranes with smaller pores had greater fouling propensity than those with larger pores. In contrast, CA hollow fiber membranes showed good mitigation of membrane fouling regardless of pore size. The results obtained in this study suggest that the surface hydrophilicity and pore size of UF membranes clearly affect the fouling properties in MBR operation when using activated sludge.
ARTICLE | doi:10.20944/preprints202108.0393.v1
Subject: Engineering, Chemical Engineering Keywords: Membrane oscillation; shear rate; slotted structure membrane; oil water separation and membrane fouling
Online: 19 August 2021 (06:51:11 CEST)
A new method is proposed to increase rejection in microfiltration by applying membrane oscillation using a new type of microfiltration membranes with slotted pores. The oscillations applied to the membrane surface result in reducing membrane fouling and increasing separation efficiency. An exact mathematical solution of the flow in the surrounding solution outside the oscillating membrane is developed. The oscillation results in appearance of the lift velocity, which moves oil particles away from the membrane. The latter results in both reducing membrane fouling and increasing oil droplets rejection. This developed model was supported by the experimental results for oil water separation in produced water treatment. It was proven that oil droplet concentration reduced notably in the permeate due to the membrane oscillation and that applied shear rate caused by the membrane oscillation is also reduce pore blockage. New generation of microfiltration membranes with slotted pores was used in the experiments.
ARTICLE | doi:10.20944/preprints201801.0091.v1
Subject: Engineering, Industrial And Manufacturing Engineering Keywords: turbulent flow; stirred flows; membrane fouling; membrane bioreactor
Online: 10 January 2018 (11:05:04 CET)
Numerical simulations of turbulent flows in a stirred dead-end membrane bioreactor are performed by the RNG k-ε model based on finite volume method using Fluent codes. Comparisons of numerical and experimental results confirm the reliability and feasibility of the constructed model. Flow structures such as wake flows and circulation loops in stirred flows were well simulated. An increase of stirring speed is proposed to use to minimize the low velocity region. The single vane stirrer is found to be beneficial for biological separations. Results reveal that the increase of vane number can enhance the mixing effect in flow domains. However, a circular disk stirrer goes against the formation of vertical circulations. The six-vane stirrer is found to be able to provide a uniform distribution of high shear stress.
ARTICLE | doi:10.20944/preprints202111.0494.v1
Subject: Chemistry And Materials Science, Analytical Chemistry Keywords: Polymer inclusion membrane (PIM); Poly(vinylidenefluoride-co-hexafluoropropylene); Vanadium(V); Extraction; Aliquat® 336
Online: 26 November 2021 (09:03:14 CET)
A polymer inclusion membrane (PIM) composed of 50 wt% poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP) as its base polymer, 40 wt% Aliquat® 336 as its extractant and 10 wt% dibutyl phthalate (DBP) as plasticizer provided efficient extraction of vanadium(V) from its sulfate solutions adjusted to pH 2.5. It was suggested that V(V) was extracted as VO2SO4− via an anion exchange mechanism. Quantitative back-extraction was achieved in a sulfuric acid solution (6 mol L-1) containing 1 v/v% of hydrogen peroxide. It was assumed that the back-extraction process involved the oxidation of VO2+ to VO(O2)+ by hydrogen peroxide. The newly developed PIM with the optimized composition mentioned above exhibited excellent selectivity for V(V) in the presence of metallic species present in digests of spent alumina hydrodesulfurization catalysts (i.e., Al(III), Co(II), Cu(II), Fe(III), Mn(II), and Ni(II)). The co-extraction of Mo(VI) with V(V) was eliminated by its selective extraction at pH 1.1. The optimized PIM was characterized by contact angle measurements, atomic-force microscopy (AFM), energy dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA)/derivatives thermogravimetric analysis (DTGA), and the stress-strain measurements.
ARTICLE | doi:10.20944/preprints201809.0242.v1
Subject: Chemistry And Materials Science, Chemical Engineering Keywords: Phospholipid assembly; Bicelle; Membrane fluidity; Membrane polarity; Phase behavior
Online: 13 September 2018 (14:45:35 CEST)
Self-assembly membranes, composed of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC), were characterized at the total lipid concentration below 20 mM. The sizes of the assemblies varied depending on the molar ratio of DMPC and DHPC (q = [DMPC]/[DHPC]). The small assemblies with diameter of ca. 10 nm were formed at q ≤ 2.0 at 20 ºC (below phase transition temperature of DMPC). The physicochemical membrane properties were then studied using fluorescence probes, 1,6-diphenyl-1,3,5-hexatriene and 6-dodecanoyl-N,N-dimethyl-2-naphthylamine, upon the dilution. DHPC micelle showed a higher membrane fluidity, while the DMPC/DHPC membranes at q ≥ 0.5 showed lower membrane fluidities as well as DMPC vesicle in gel (ordered) phase. Upon dilution, the ordered membrane properties were maintained while the solution turbidities increased, implying the morphological change of the self-assembly, bicelle to the vesicle in gel phase. Based on the obtained results, a phase diagram of DMPC/DHPC binary system (at 20 ºC) is described: (i) the bicelle suspension is transparent and the membrane is in ordered state, (ii) the micelle suspension is transparent and the membrane is in disordered state, (iii) the vesicle suspension is turbid and the membrane is in ordered state.
ARTICLE | doi:10.20944/preprints201807.0112.v1
Subject: Chemistry And Materials Science, Surfaces, Coatings And Films Keywords: membrane distillation; polyvinylidene fluoride; copper oxide nanoparticles; membrane morphology
Online: 6 July 2018 (09:03:09 CEST)
Membrane distillation techniques appear as one of the most promise alternative to guarantee the availability of potable water in time of scarce of this essential resource. For membrane preparation, polyvinylidene fluoride (PVDF) is preferred due to the easier synthesis procedures with respect to other fluorine based polymers. In this work, copper oxide nanoparticles (CuONPs) at different weight percent (wt.%), embedded in PVDF membranes supported on non-woven polyester fabric (NWPET) were prepared by the phase-inversion method, and characterized by spectroscopy (ATR-FTIR, Raman) and electron microscopy techniques (SEM). The PVDF deposited onto the NWPET was highly composed by its polar -phase (F()= 53 %) which was determined from the ATR-FTIR spectrum. The F() value was kept constant, in the whole range of CuONPs studied (2-10 wt.%) as was determined from the ATR-FTIR spectrum. The absence of signals corresponding to CuONPs in the ATR-FTIR spectra and the appearance of peaks at 297, 360 and 630 cm-1 in the Raman spectra of the membranes suggested that the CuONPs are preferably located in the inner of the membrane but not on its surface. The membrane morphologies were characterized by SEM. From the obtained SEM micrographs, a decrease and increase in the amount of micropores and nanopores, respectively, near to the surface and intercalated in the finger-like layer were observed. As result of the CuONPs addition, the nanopores in the sponge-like layer decrease in size. The values of water contact angle (WCA) measurements showed a trend to decrease from 94° to 80° upon the addition of CuONPs (2-10 wt.%) indicating a diminish in the hydrophobicity degree of the membranes. Apparently, the increase in the amount of nanopores near to the surface decreased the membrane roughness becoming less hydrophobic.
ARTICLE | doi:10.20944/preprints202310.0270.v1
Subject: Chemistry And Materials Science, Medicinal Chemistry Keywords: synthetic membrane; mucosa membrane; waterproofing formulations; TMWL; in vitro release
Online: 5 October 2023 (10:54:08 CEST)
This work presents the possibility of using a synthetic membrane for pretracing mucosal penetration studies. The permeability of two types of membranes, porcine oral mucosa and a synthetic Nuclepore membrane, to water was compared. Moreover, the water permeability of membranes modified with waterproofing formulations was measured to study their ability to protect against the penetration of viruses, toxins, etc. A very good correlation was obtained between the transmucosal water loss (TMWL) values of the artificial membrane and the mucosa. These results support the possible use of this synthetic membrane in the screening of the water permeability of formulations. In addition, studies of the permeation of different actives, drugs and biocides through the two membranes were carried out, and these results were compared with their skin permeation data. The synthetic membrane does not seem to discern between compounds in terms of permeability, which could be due to the lack of lipids in the composition of this synthetic membrane. Therefore, Nuclepore alone cannot be used as a model for the release of actives. Additionally, the permeation of caffeine through intact or modified membranes incorporating waterproofing formulations was also studied. In this case, similar permeation profiles through the synthetic membrane and mucosa were found. The results from these assays should lend support to the use of this synthetic membrane when screening formulations to be applied in oral penetration studies.
ARTICLE | doi:10.20944/preprints202305.1577.v1
Subject: Engineering, Chemical Engineering Keywords: polyvinylidene fluoride-co-hexafluoropropylene; Electrospinning; Nanofibers; Hydrophobic membrane; Membrane distillation
Online: 23 May 2023 (05:06:09 CEST)
The major challenge for membrane distillation (MD) is membrane wetting resistance induced by pollutants in the feed solution. The proposed solution for this issue was to fabricate membranes with hydrophobic properties. Hydrophobic electrospun Poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanofibers membranes were produced for brine treatment using the direct contact membrane distillation (DCMD) technique. These nanofibers membranes were prepared from three different polymeric solution compositions to study the effect of solvent composition in the electrospinning process. Further, the effect of the polymer concentration was investigated by preparing polymeric solutions with three different polymer percentages: 6, 8, and 10%. All nanofibers membranes obtained from electrospinning were post-treated at varying temperatures. The effects of thickness, porosity, pore size, and LEP were studied. The hydrophobicity was determined by contact angle measurements, which were investigated by optical contact angle goniometry. The crystallinity and thermal properties were studied by DCS and XRD, while the functional groups were studied by FTIR. The morphological study was performed by AMF and described the roughness of nanofibers membranes. Finally, all nanofibers membranes have enough of a hydrophobic nature to be used in DCMD. PVDF membrane filter disc and all nanofibers membranes were applied in DCMD to treat brine water. The resulting water flux and permeate water quality were compared, and it was discovered that all produced nanofibers membranes showed good behavior with varying water flux, but the salt rejection was greater than 90%. A membrane prepared from DMF/acetone 5-5 with 10% PVDF-HFP provided perfect performance, with an average water flux of 44 kg.m-2.h-1 and salt rejection of 99.8%.
ARTICLE | doi:10.20944/preprints201810.0321.v1
Subject: Biology And Life Sciences, Cell And Developmental Biology Keywords: amniotic membrane; epithelialization; inflammation; ocular surface disorders; anti-fibrotic action, amniotic membrane eye drop, amniotic membrane graft transplantation
Online: 15 October 2018 (14:35:06 CEST)
The aim of this study is to emphasize on the clinical uses of amniotic membrane (AM) in multiple ocular disorders. AM possesses many properties including promotion of epithelialization, anti-fibrotic, anti-apoptotic, anti-angiogenic properties. Epithelial wound healing on the eye surface is promoted due to several epidermal and keratocyte growth factors as well as by its anti-inflammatory and anti-scarring effects due to interleukin-10, interleukin-1 receptor antagonists and inhibition of transforming growth factor- beta (TGF-β) signal transduction by AM in the corneal and conjunctival fibroblasts respectively. It plays a crucial role by functioning as a substitute of basement membrane (BM) and as a temporary graft material. It is not only being used as an eye graft but also its extract can be used as an eye drop for corneal and external eye diseases. So its proper preparation, preservation and clinical application can bring a revolutionary change in the treatment of different ocular disorders.
ARTICLE | doi:10.20944/preprints202309.0874.v1
Subject: Chemistry And Materials Science, Electrochemistry Keywords: computational fluid dynamics; hollow fiber membrane; 2D materials; membrane partition coefficient
Online: 13 September 2023 (10:32:57 CEST)
The current study presents a computational fluid dynamics model designed to simulate the isolation of 2D graphene components from their dispersion using a microfiltration hollow fiber membrane unit. The model utilizes Navier-Stokes and mass conservation equations to predict the flow and concentration behaviors in the system, and it employs the resistance-in-series approach to couple the fouling of the non-exfoliated graphites in the dispersion to the model. Specifically, the model accounts for the effects of the concentration polarization and cake formation of the fouling component, resulting in the increment of the transmembrane pressure (TMP) of the system. Additionally, we assumed the wettability of polymeric membrane’s inner wall enhances upon fouling by the flat layered structure material, leading to the reduction of the transmemrabe pressure. This approach demosntrates accurate reproduction of the exceptional experimental TMP behavior corresponding to the fouling of the graphite.
Subject: Engineering, Chemical Engineering Keywords: membrane theory; Association-Induction Hypothesis; ion transport, ion adsorption; membrane potential
Online: 13 August 2021 (08:53:04 CEST)
Accurate prediction of the membrane potential by membrane theory is possible on the basis that the plasma membrane is selectively permeable to ions and that permeability determines the characteristics of the membrane potential. However, an experimental and artificial cell system with an impermeable membrane serving as a model plasma membrane has a non-zero membrane potential, and this potential generated across the membrane is somehow consistent with the potential characteristics predicted by the membrane theory, despite the impermeability of the membrane to ions. A long-forgotten theory, called the association-induction hypothesis (AIH), has emerged as a more plausible mechanism for generating the membrane potential than the membrane theory to explain this unexpected behavior. The AIH asserts that ion-selective membrane permeability is not necessary for the generation of the membrane potential, which is contrary to the membrane theory. Although such an idea is not easy to accept, the experimental results clearly suggest the correctness of the AIH.
HYPOTHESIS | doi:10.20944/preprints202012.0813.v1
Subject: Medicine And Pharmacology, Immunology And Allergy Keywords: Alzheimer’s disease; beta-amyloid; protease; membrane; membrane channel; lysosome; autophagy; mitochondrion
Online: 31 December 2020 (13:32:26 CET)
Alzheimer's disease (AD) is the most common cause of dementia and affects millions of people around the world. Neuronal death in AD is initiated by the toxic action of oligomeric amyloid-β (Aβ) peptides. The formation of membrane channels by Aβ is a primary molecular action and does not require any other proteins. Channels are formed by short amyloid fragments faster and more frequently than by full-length peptides. The channel formation is dependent on an electrostatic interaction between a positively charged peptide and a negatively charged membrane. Negative membranes can be found in several locations of a cell – the inner leaflet of plasma membrane, mitochondria, and lysosomes, which all are well-known cellular targets in AD. Considering that the amyloid enters a cell by endocytosis and is exposed to lysosomal enzymes, we propose the amyloid degradation toxicity hypothesis. Endopeptidases degrade the endocytosed peptide. Produced fragments form membrane channels, which can transfer various ions (including protons) and even relatively large compounds. The neutralization of lysosomal content inactivates enzymes, which fails the whole system of recycling cellular content, including autophagy. The permeabilization of lysosomes could also lead to cell death through necrotic and apoptotic mechanisms. We discuss several mechanisms that describe how amyloid degradation products reach plasma and mitochondrial membranes, and form membrane channels. The pathogenesis of AD is discussed at various levels in a context of how the primary molecular mechanism of membrane channel formation could progress into the disease state. The discussion starts at the molecular level and extends to why the development of a disease takes years and is closely associated with aging. The proposed hypothesis offers an interpretation to several clinical observations such as the involvement of iron metabolism and an inverse association between developing Alzheimer's disease and cancer. Predictions about potential biomarkers and effectiveness of future treatments are discussed.
ARTICLE | doi:10.20944/preprints201807.0387.v1
Subject: Chemistry And Materials Science, Polymers And Plastics Keywords: membrane fouling; membrane plasticization; nutrients transport properties; perfusion bioreactors; tissue engineering
Online: 20 July 2018 (14:01:37 CEST)
High porosity and mass transport properties of microfiltration polymeric membranes benefits nutrients supply to cells when used as scaffolds in interstitial perfusion bioreactors for tissue engineering. High nutrients transport is assumed when pore size and porosity of the membrane are in the micrometric range. The present work demonstrates that the study of membrane fouling by proteins present in the culture medium, though not done usually, should be included in the routine testing of new polymer membranes for this intended application. Two poly(ε-caprolactone) microfiltration membranes presenting similar average pore size (~0.7µm) and porosity (>80%) but different external surface porosity and pore size have been selected as case study. The present work demonstrates that a membrane with lower surface pore abundance and smaller external pore size (~0.67 µm), combined with adequate hydrodynamics and tangential flow filtration mode is usually more convenient to guarantee high flux of nutrients. On the contrary, having large external pore size (~1.70µm) and surface porosity would incur in important internal protein fouling that could not been prevented with the operation mode and hydrodynamics of the perfusion system. Additionally, the use of glycerol in the drying protocols of the membranes might cause plasticization and a consequent reduction of mass transport properties due to membrane compaction by the pressure exerted to force perfusion. Therefore, preferentially, drying protocols that omit the use of plasticizing agents are recommended.
ARTICLE | doi:10.20944/preprints201804.0078.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: membrane fatty acids composition; Staphylococcus aureus; staphyloxanthin; membrane fluidity; metabolic regulation
Online: 6 April 2018 (11:37:53 CEST)
Fatty acids play a major role in determining membrane biophysical properties. Staphylococcus aureus produces branched-chain fatty acids (BCFAs) and straight-chain fatty acids (SCFAs), and can incorporate exogenous SCFAs and straight-chain unsaturated fatty acids (SCUFAs). Many S. aureus strains produce the triterpenoid pigment staphyloxanthin, and the balance of BCFAs, SCFAs and staphyloxanthin determines membrane fluidity. Here, we investigated the relationship of fatty acid and carotenoid production in S. aureus using a pigmented strain (Pig1), its carotenoid-deficient mutant (Pig1ΔcrtM) and the naturally non-pigmented Staphylococcus argenteus that lacks carotenoid biosynthesis genes and is closely related to S. aureus. Fatty acid compositions in all strains were similar under a given condition indicating that staphyloxanthin does not influence fatty acid composition. Strain Pig1 had decreased membrane fluidity as measured by fluorescence anisotropy than the other strains under all conditions indicating that staphyloxanthin helps maintain membrane rigidity. We could find no evidence for correlation of expression of crtM and fatty acid biosynthesis genes. Supplementation of medium with glucose increased SCFA production and decreased BCFA and staphyloxanthin production, whereas acetate-supplementation also decreased BCFAs but increased staphyloxanthin production. We believe that staphyloxanthin levels are influenced more through metabolic regulation than responding to fatty acids incorporated into the membrane.
ARTICLE | doi:10.20944/preprints202305.1876.v1
Subject: Medicine And Pharmacology, Clinical Medicine Keywords: amniotic membrane allografts; cryopreserved amniotic membrane; lyophilization; freeze-dried amniotic membrane; N-acylethanolamines; palmitoylethanolamide; tissue banking; mass spec-trometry
Online: 26 May 2023 (07:29:40 CEST)
To compare concentrations of endogenous N-acylethanolamines (NAEs) lipid mediators pal-mitoylethanolamide (PEA), oleoylethanolamide (OEA), and anandamide (AEA) in fresh, decon-taminated, cryopreserved and freeze-dried amniotic membrane (AM) allografts. Thereby deter-mining whether AM's analgesic and anti-inflammatory efficiency related to NAEs persists during storage. The concentrations of NAEs were measured using ultra-high-performance liquid chro-matography-tandem mass spectrometry. Indirect fluorescent immunohistochemistry was used to detect the PEA PPARα receptor. The concentrations of PEA, OEA, and AEA were significantly higher after decontamination. A significant decrease was found in cryopreserved AM compared to decontaminated tissue for PEA but not for OEA and AEA. However, significantly higher val-ues for all NAEs were detected in cryopreserved samples compared to fresh tissue before decon-tamination. The freeze-dried AM had similar values to decontaminated AM with no statistically significant difference. The nuclear staining of PPARα receptor was clearly visible in all specimens. The stability of NAEs in AM after cryopreservation was demonstrated under tissue bank storage conditions. However, a significant decrease, but still higher concentration of PEA compared to fresh not decontaminated tissue was found in cryopreserved, but not frieze-dried AM. Results in-dicate that NAEs persist during storage in levels sufficient for the analgesic and anti-inflammatory effects of AM allografts.
REVIEW | doi:10.20944/preprints201810.0307.v1
Subject: Medicine And Pharmacology, Ophthalmology Keywords: Keywords: amniotic membrane; epithelialization; inflammation; ocular surface disorders; anti-fibrotic action, amniotic membrane eye drop, amniotic membrane graft transplantation.
Online: 15 October 2018 (12:06:21 CEST)
Abstract: The aim of this study is to emphasize on the clinical uses of amniotic membrane (AM) in multiple ocular disorders. AM possesses many properties including promotion of epithelialization, anti-fibrotic, anti-apoptotic, anti-angiogenic properties. Epithelial wound healing on the eye surface is promoted due to several epidermal and keratocyte growth factors as well as by its anti-inflammatory and anti-scarring effects due to interleukin-10, interleukin-1 receptor antagonists and inhibition of transforming growth factor- beta (TGF-β) signal transduction by AM in the corneal and conjunctival fibroblasts respectively. It plays a crucial role by functioning as a substitute of basement membrane (BM) and as a temporary graft material. It is not only being used as an eye graft but also its extract can be used as an eye drop for corneal and external eye diseases. So its proper preparation, preservation and clinical application can bring a revolutionary change in the treatment of different ocular disorders.
ARTICLE | doi:10.20944/preprints202309.1888.v1
Subject: Biology And Life Sciences, Life Sciences Keywords: antidiabetic, anti-inflammatory activity, Artemisia absinthium, Artemisia vulgaris, Trigonella foenum-graecum, membrane technologies, α-amylase, α-glucosidase, hyaluronidase, lipoxygenase
Online: 28 September 2023 (03:23:11 CEST)
In recent years there has been increasing interest in the discovery of new natural herbal remedies for the treatment of common conditions such as diabetes and inflammatory diseases. In this context, this paper analyzed the antidiabetic and anti-inflammatory potential of two plants of the genus Artemisia: Artemisia absinthium (wormwood) and Artemisia vulgaris (mugwort) and Trigonella foenum-graecum (fenugreek) plants less studied from this point of view. Thus, hydroal-coholic extracts (50% EtOH v/v, 10% mass) were made, which were processed by membrane technologies, micro- and ultrafiltration, in order to concentrate the biologically active principles. The extracts were then analyzed in terms of content in active principles of interest (polyphenols, flavones). The antidiabetic activity of the extracts was analyzed by testing their ability to inhibit α-amylase and α-glucosidase and the anti-inflammatory activity by testing the ability to inhibit hyaluronidase (HYA) and lipoxygenase (LOX). Thus, the T. foenum-graecum extracts showed a high inhibitory activity on α-amylase 3.22 ± 0.3 g / mL (compared to the standard used - IC50 acarbose = 3.5 g / mL) and a high inhibitory activity on LOX: 19.69 ± 0.52 g/mL (compared to all standards used). The concentrated extract of Artemisia vulgaris showed increased activity of inhibition of α-amylase - IC50 = 8.57 ± 2.31g/mL and moderate activity of inhibition of HYA - IC50 = 17.18 g/mL compared to ibuprofen, the standard used - IC50 = 5.73 g/mL. The concentrated extract of Artemisia absinthium showed a pronounced activity of inhibition of LOX - IC50 = 19.71 g / mL, compared to the standard - rutin - IC50 = 22.34 g/mL).
ARTICLE | doi:10.20944/preprints201801.0211.v1
Online: 23 January 2018 (06:43:31 CET)
A membrane can be represented by an energy landscape that solutes or colloids must cross. A model accounting for the momentum and the mass balances on the membrane energy landscape establishes a new way of writing for the Darcy law. The counter pressure in the Darcy law is no longer written as the result of an osmotic pressure difference but rather as a function of colloid-membrane interactions. The ability of the model to describe the physics of the filtration is discussed in detail. This model is solved on a simplified energy landscape to derive analytical relationships that describe the selectivity and the counter pressure from ab-initio operating conditions. The model shows that the stiffness of the energy landscape has an impact on the process efficiency: a gradual increase in interactions (like with hourglass pore shape) can reduce the separation energetic cost. It allows the introduction of a new paradigm to increase membrane efficiency: the accumulation that is inherent to the separation must be distributed across the membrane. Asymmetric interactions thus lead to direction-dependent transfer properties and the membrane exhibits diode behavior. These new transfer opportunities are discussed.
ARTICLE | doi:10.20944/preprints201709.0010.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: GBR; membrane; surface modification
Online: 4 September 2017 (18:25:01 CEST)
Titanium membranes are used for guided bone regeneration in implant therapy. However, as a bioinert material, titanium does not have the ability to accelerate bone formation. Various titanium surface treatments to confer bioactivity have been demonstrated; however, there are concerns about the influence of chemical treatments on the corrosion of thin titanium membranes. This study investigated the influence of surface modifications on the structure of thin titanium membranes. Titanium membranes of 20 µm thickness were treated with acid or alkali solutions, and we evaluated their surface structure, wettability, corrosion depth, and mechanical strength compared to non-treated membranes. Alkali-treated thin titanium membranes displayed the formation of nanoscale pore structures on their surfaces, enhanced hydrophilicity, and less corrosion depth compared with acid-treated membranes. Furthermore, the tensile strength of alkali-treated membranes was comparable to non-treated membranes. These results suggest that alkali treatment is an appropriate surface modification method for thin titanium membranes.
REVIEW | doi:10.20944/preprints202207.0180.v1
Subject: Medicine And Pharmacology, Neuroscience And Neurology Keywords: plasma membrane; membrane domains; nanodomains; neurotransmitter receptors; cannabinoids; acetylcholine receptor; cannabinoid receptor.
Online: 12 July 2022 (09:17:01 CEST)
Fifty years on from the classical fluid-mosaic model of Singer and Nicolson, current views of the plasma membrane portray a much more complex view of this interface region. Compartmentalization, together with transbilayer and lateral asymmetries, provide the structural foundation for functional specializations at the cell surface, including the active role of the lipid microenvironment in the modulation of membrane-bound proteins. The chemical synapse, the site where neurotransmitter-coded signals are decoded by neurotransmitter receptors, adds another layer of complexity to the plasma membrane architectural intricacy, mainly due to the need to accommodate a sizeable number of molecules in a minute subcellular compartment with dimensions barely reaching the micrometer. In this review, we discuss how Nature has developed suitable adjustments to accommodate different types of membrane-bound receptors and scaffolding proteins via membrane microdomains, and how this “efford-sharing” mechanism has evolved to optimize crosstalk or separation or coupling where/when appropriate. To this end, we use a fast ligand-gated neurotransmitter receptor, the nicotinic acetylcholine receptor, and a second-messenger G-protein coupled receptor, the cannabinoid receptor, as paradigmatic example.
ARTICLE | doi:10.20944/preprints201807.0460.v1
Subject: Engineering, Chemical Engineering Keywords: N-nitrosamines; formation potential; membrane treatment; reverse osmosis; membrane fouling; pilot-scale
Online: 24 July 2018 (15:46:34 CEST)
This study investigated the removal characteristics of N-nitrosamines and their precursors at three pilot-scale water reclamation plants. These plants applies different integrated membrane systems: (1) microfiltration (MF) / nanofiltration (NF) / RO; (2) sand filtration/three-step RO; and (3) ultrafiltration (UF) / NF and UF / RO. Variable removal of N-nitrosodimethylamine (NDMA) by the RO membrane processes could be attributable to membrane fouling and feed water temperature. The effect of membrane fouling on N-nitrosamines removal was extensively evaluated at one of the plants by conducting one month of operation and chemical cleaning of the RO membrane element. Membrane fouling enhanced N-nitrosamines removal by the pilot-scale RO membrane process. This finding contributes to better understanding of variable removal of NDMA by RO membrane processes. This study also investigated the removal characteristics of N-nitrosamines precursors. The NF and RO membrane processes greatly reduced NDMA formation potential (FP), but the UF process had little effect. The contributions of MF, NF, and RO membrane processes for reducing FPs of NDMA, N-nitrosopyrrolidine (NPYR) and N-nitrosodiethylamine (NDEA) were different, suggesting different size distributions of their precursors.
Subject: Biology And Life Sciences, Biophysics Keywords: cytosolic phospholipase A2; electron microscopy; C2 domain; Golgi; membrane bending; membrane curvature; oligomerization
Online: 12 March 2020 (04:10:52 CET)
Group IV phospholipase A2α (cPLA2α) regulates the production of prostaglandins and leukotrienes via the formation of arachidonic acid from membrane phospholipids. The targeting and membrane binding of cPLA2α to the Golgi involves the N-terminal C2 domain whereas the catalytic domain produces arachidonic acid. Although most studies of cPLA2α concern its catalytic activity, it is also linked to homeostatic processes involving the generation of vesicles that traffic material from the Golgi to the plasma membrane. Here we investigate how membrane curvature influences the homeostatic role of cPLA2α in vesicular trafficking. The cPLA2α C2 domain is known to induce changes in positive membrane curvature, a process which is dependent on cPLA2α membrane penetration. We show that cPLA2α undergoes C2 domain-dependent oligomerization on membranes in vitro and in A549 cells. We found that the association of the cPLA2α C2 domain with membranes is limited to membranes with positive curvature, and enhanced C2 domain oligomerization was observed on vesicles ~50 nm in diameter. We demonstrated that the cPLA2α C2 domain generates cholesterol enriched Golgi-derived vesicles independently of cPLA2α catalytic activity. Our results therefore provide novel insight into the molecular forces that mediate C2 domain-dependent membrane localization in vitro and in cells.
ARTICLE | doi:10.20944/preprints201911.0012.v4
Subject: Chemistry And Materials Science, Polymers And Plastics Keywords: interfacial polymerization; in-situ FT-IR spectroscopy; thin-film composite membrane; nanofiltration membrane
Online: 8 January 2020 (09:04:29 CET)
The interfacial polymerization (IP) of piperazine (PIP) and trimesoyl chloride (TMC) has been extensively utilized to synthesize nanofiltration (NF) membranes. However, it is still a huge challenge to monitor the IP reaction, because of the fast reaction rate and the formed ultra-thin film. Herein, two effective strategies were applied to reduce the IP reaction rate: (1) the introduction of hydrophilic interlayers between the porous substrate and the formed polyamide layer, and (2) the addition of macromolecular additives in the aqueous solution of PIP. As a result, in situ Fourier transform infrared (FT-IR) spectroscopy was firstly used to monitor the IP reaction of PIP/TMC with hydrophilic interlayers or macromolecular additives in the aqueous solution of PIP. Moreover, the formed polyamide layer growth on the substrate was studied in a real-time manner. The in situ FTIR experimental results confirmed that the IP reaction rates were effectively suppressed and that the formed polyamide thickness was reduced from 138 ± 24 nm to 46 ± 2 nm according to TEM observation. Furthermore, an optimized NF membrane with excellent performance was consequently obtained, which included boosted water permeation of about 141–238 (L/m2·h·MPa) and superior salt rejection of Na2SO4 > 98.4%.
REVIEW | doi:10.20944/preprints202305.1708.v1
Subject: Biology And Life Sciences, Life Sciences Keywords: Cytoplasmic membrane homeostasis; Pathogenicity; Pathogenic fungi; Membrane lipid metabolism; Membrane curvature; Transmembrane protein; Cell wall components; Cytoskeleton; Growth and development; Host infection
Online: 24 May 2023 (10:38:22 CEST)
The cytoplasmic membrane is the fundamental component of all living cells, which participates in various physiological processes, such as material exchange, stress response, cell recognition, signal transduction, cellular immunity, apoptosis, pathogenicity, etc. The normal function of a cytoplasmic membrane requires stable organization of transmembrane protein-lipid microdomains, transmembrane protein-cell wall microdomains, and cytoskeleton-transmembrane protein microdomains. Here, we review the mechanisms and functions of various membrane lipid components, fatty acid content and saturation, membrane curvature, and cell wall and cytoskeleton in plasma membrane homeostasis affecting the pathogenicity of pathogenic fungi. Pathogenic fungi maintains plasma membrane homeostasis and contributes to fungal virulence by maintaining plasma membrane assembly, structural and functional integrity of pathogenic fungi at various stages of cell development through interactions among lipid components of cytoplasmic membranes, transmembrane proteins, cytoskeleton and cell wall components, etc.
ARTICLE | doi:10.20944/preprints202002.0263.v1
Subject: Chemistry And Materials Science, Applied Chemistry Keywords: liquid membrane; ionic liquid; gold
Online: 18 February 2020 (10:43:15 CET)
On the system Au(III)-HCl-A324H+Cl-, liquid-liquid extraction experiments were used to define the extraction equilibrium and the corresponding extraction constant, and the facilitated transport of this precious metal, from HCl solutions, across a flat-sheet supported liquid membrane was investigated, using the ionic liquid as carrier, as a function of hydrodynamic conditions, concentration of gold(III) (0.01-0.1 g/L), and HCl (0.5-6 M) in the feed phase, and carrier concentration (0.023-0.92 M) in the membrane. An uphill transport equation was derived considering aqueous feed boundary layer diffusion and membrane diffusion as controlling steps. The aqueous diffusional resistance (Δf) and the membrane diffusional resistance (Δm) were estimated from the proposed equation, being their values 241 s/cm an 9730 s/cm, respectively. The performance of the present carrier was compared against results yielded by other ionic liquids, and also it was investigated the influence that other metals had on gold(III) transport both from binary or quaternary solutions. Gold was finally recovered from receiving solutions as zero valent gold nanoparticles.
ARTICLE | doi:10.20944/preprints202001.0348.v1
Subject: Chemistry And Materials Science, Chemical Engineering Keywords: PEBAX; Ag; olefin; membrane; nanoparticle
Online: 29 January 2020 (04:35:25 CET)
PEBAX-2533/metal salt/Al salt membranes were prepared for mixed olefin/paraffin separation. PEBAX-2533 with 80% ether group and 20% amide group was suggested as the polymer matrix for comparison of separation performance according to the functional group ratio in copolymer PEBAX. In addition, Al salts were used to stabilize metal ions for a long time as additives. High permeance was expected with the proportion of high ether groups since these functional groups provided relatively permeable regions. As a result, the PEBAX-2533 composite membrane showed a selectivity of 5 (propylene/propane) with 10 GPU. However, the permeance of membrane was not unexpectedly improved and the selectivity was reduced. The result was analyzed by SEM, FT-RAMAN and TGA, including FT-IR. The reduction in separation performance was determined by FT-IR. From these results, in order to stabilize the metal ions interacting with the polymer through Al(NO3)3, it was concluded that specific ratio of amide group was needed in PEBAX as polymer matrix.
REVIEW | doi:10.20944/preprints202306.1372.v1
Subject: Biology And Life Sciences, Life Sciences Keywords: Cryptococcus; biofilm; metabolic enzymes; virulence factors; transcription factors; membrane permeases; membrane transporters; catabolite repression
Online: 19 June 2023 (14:43:36 CEST)
Cryptococcus neoformans is a pathogenic fungus that causes cryptococcosis, a significant secondary infection in immunocompromised individuals with immune-suppressive related symptoms from HIV infection and organ transplants. Fungaemia occurs via the respiratory route and spreads by tissue invasion into other body parts. Enzymes and membrane-associated permeases/transporters are accessory proteins deployed to enhance the survival, adaptation, and infection caused by Cryptococcus species. The nutrient bioavailability determines the functional turnover rate of these proteins in the immediate fungal environment. Low oxygen levels in the internal organs, essential micro-elements locked in the storage proteins, catabolite repression, phagolysosomal low glucose level and pH, tight junction, and extracellular matrixes are challenges to the survival of this pathogen in the host. This review identifies key hydrolytic and metabolic enzymes and permeases/transporters as essential weapons of virulence in addition to survival, tolerance, resistance, adaptation, and infection in humans. Under the regulation of different transcription factors, these proteins are released in response to nutrient sensors designed to siphon the host nutrients and induce infection in predisposed individuals. The extracellular secretory vesicles called “exosomal virulence bag” also harbour cryptococcal urease, laccase, phosphatase, and capsular components as additional secretory protein weapons for immune evasion, tissue invasion and persistence.
ARTICLE | doi:10.20944/preprints201902.0082.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: positional isomerism; PUFA biosynthesis; membrane remodelling; membrane lipidomics; lipidomic analysis; fluidity; functional two photon microscopy
Online: 8 February 2019 (09:43:06 CET)
Palmitic acid metabolism involves delta-9 and delta-6 desaturase enzymes forming palmitoleic acid (9cis-16:1; n-7 series) and sapienic acid (6cis-16:1; n-10 series), respectively. The corresponding biological consequences and lipidomic research on these positional MUFA isomers are under development. Furthermore, sapienic acid can bring to the de novo synthesis of the n-10 polyunsaturated fatty acid (PUFA) sebaleic acid (5cis,8cis-18:2), but such transformations in cancer cells are not known. The model of Caco-2 cell line was used to monitor sapienic acid supplementation (150 and 300 μM) and evidence the formation of n-10 fatty acids as well as their incorporation at levels of membrane phospholipids and triglycerides. Comparison with palmitoleic and palmitic acids evidenced that lipid remodeling was influenced by the type of fatty acid and positional isomer, with increase of 8cis-18:1, n-10 PUFA and decrease of saturated fats in case of sapienic acid. Cholesteryl esters were formed only in case of sapienic acid. EC50 of sapienic acid (232.3 μM at 96 hrs) was the highest found among the tested fatty acids, thus influencing cell viability that was only reduced at 25% at 300 μM, whereas palmitoleic acid induced cell death. Two-photon fluorescent microscopy with Laurdan as a fluorescent dye provided information on membrane fluidity, highlighting that sapienic acid increases the distribution of fluid regions, probably connected with the formation of 8cis-18:1 and the n-10 PUFA in cell lipidome. Our results bring evidence for MUFA positional isomers and de novo PUFA synthesis for developing lipidomic analysis and cancer research.
ARTICLE | doi:10.20944/preprints202310.1940.v1
Subject: Physical Sciences, Theoretical Physics Keywords: Black Holes; Membrane Paradigm; Relativistic Hydrodynamics
Online: 31 October 2023 (05:19:32 CET)
We consider subtleties of the horizon (null-hypersurface) limit in the Parikh-Wilczek Membrane Approach to Black Holes. Specifically, we refine the correspondence between the (projected) Einstein equations of gravity with matter and the Raychaudhuri-Damour-Navier-Stokes (RDNS) equations of relativistic hydrodynamics. For a general configuration of gravity with matter we obtain additional terms in the hydrodynamic equations, which include logarithmic derivarives of a parameter (the regularization function) determining the proximity of a stretched membrane to the BH horizon. Direct computation of the new terms for exact (Schwarzschild and Kerr) solutions to the Einstein equations results in vanishing the additions to the RDNS equations in the horizon limit. For spacetimes, which are not exact solutions to the Einstein equations, as, for instance, for space-time configurations mimicking black holes, taking into account new terms in the RDNS equations is the mandatory operation. We also comment the correspondence between the horizon limit of the Parikh-Wilczek Membrane Approach and the Gourgoulhon-Jaramillo method of a null-hypersurface description, as well as the link of the obtained results to our previous work on the Kerr black holes.
ARTICLE | doi:10.20944/preprints202310.0051.v1
Subject: Medicine And Pharmacology, Medicine And Pharmacology Keywords: angiogenesis; nutraceuticals; chorioallantoic membrane; anthocyanins; tocotrienols.
Online: 2 October 2023 (11:01:58 CEST)
Angiogenesis is a process whereby new blood vessels are born from preexistent ones, which has a role in transporting oxygen and nutrients. On the other hand, inhibiting this process is a strategy used to treat some diseases, including cancers, diabetic retinopathy, and rheumatoid arthritis. This study investigates the effect of a new nutraceutical (Terasen®) on angiogenesis. Terasen® is made from a standardized extract of Euterpe oleraceae (Açaí), Myrciaria dubia (Camu-Camu), and purified oil of Bixa orellana (Annatto) and Astrocaryum aculeatum (Tucumã). The in vivo angiogenesis model used was the chorioallantoic membrane (CAM) from chicken embryos. The embryos were divided into seven groups: a vehicle control treated with ethanol solution (ETH), a naïve control treated only with saline solution (SOR), a positive control treated with dexamethasone (DEX), and four groups treated with Terasen® at different concentrations (0.5, 1, 2, and 3 mg/ml). The parameters assessed were the vessels’ area, length, and amount. The results show a statistically significant and concentration-dependent inhibition of angiogenesis caused by Terasen®. Our results suggest the nutraceutical has a high antiangiogenesis potential, possibly due to its bioactive compounds, including anthocyanins, quercetin, and tocotrienols.
ARTICLE | doi:10.20944/preprints202307.0618.v1
Subject: Engineering, Metallurgy And Metallurgical Engineering Keywords: PVA, Flexibility, Glycerol, Membrane, Mechanical properties
Online: 10 July 2023 (11:33:11 CEST)
The main goal of this study was to introduce glycerol as a plasticizer to Polyvinyl Alcohol (PVA) membranes in order to increase their flexibility. The qualities of PVA membranes produced with various glycerol concentrations were evaluated. With the modified PVA membranes containing 5% glycerol, encouraging results were obtained. These membranes had superb optical characteristics and a 90% transmittance rate. This shows that the membranes are suited for applications needing excellent optical clarity since they permit light to travel through with little distortion. Importantly, FTIR analysis demonstrated that the addition of glycerol had no effect on the PVA membranes' chemical composition or structural integrity. In comparison to pure PVA Membrane, the modified membranes' water barrier qualities showed a considerable drop of up to 50%. The membranes are useful for applications requiring moisture management or breathability because of the decline, which points to an increase in permeability to water vapour. The large increase in flexibility, which was achieved by the PVA membranes containing 5% glycerol and beyond the brittleness typically associated with pure PVA, was a noteworthy discovery. The possible applications are expanded due to the increased flexibility, especially in industries where adaptability and flexibility are essential. Additionally, the addition of glycerol improved the thermal stability of the membranes, as they showed increased resistance to breakdown or decomposition at high temperatures. Additionally, the modified membranes' mechanical qualities were better than those of pure PVA, indicating that the glycerol addition improved their overall mechanical performance and tensile strength. PVA membranes were effectively made more flexible by adding 5% glycerol as a plasticizer. This led to membranes with superior optical qualities, reduced water barrier properties, greater flexibility, improved thermal stability, and maybe improved mechanical capabilities. These discoveries open up new opportunities for the use of these flexible PVA membranes in a range of settings, such as flexible packaging, biomedical materials, and other industries that need adaptive and flexible materials.
ARTICLE | doi:10.20944/preprints202305.1122.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: graphene oxide; carboxymethylcellulose; membrane; nanocomposite; resistivity
Online: 16 May 2023 (07:55:44 CEST)
In nowadays, the synthesis of new composite nanomaterials based on graphene oxide (GO) modified with cellulose and its derivatives, as well as nanocellulose, is an important direction and contributes to solve many problems in various fields such as: nanotechnology, information technology, medicine, high-dielectric materials and nanoelectronics. In this work, for the first time, for the production of GO and its membrane with carboxymethylcellulose (CMC), local Kazakhstan “Ognevsky” graphite was used as the initial raw material. In this regard, the preparation of nanocomposites of GO modified with cellulose derivatives, including CMC, attracts great interest from scientists and expands its field of practical application due to the amazing changes of physicochemical properties. In the work, the GO obtained by the Hummers method was modified by CMC, with following study of its physicochemical, structural and electrical characteristics. The GO/CMC membrane was synthesized by mixing 1% GO with crushed solid mass of CMC (0.03 g; 0.06 g; 0.15 g) and then was processed by ultrasound. The surface morphology of the GO/CMC membrane were studied using Scanning electron microscopy (SEM). It has been established that with an increasing in the mass of CMC (0.03 g; 0.06 g; 0.15 g), polymerization of CMC occurs on the surface of GO nanosheets. Cross-sectional micrographs of GO/CMC show the formation of sandwich-like layered structures.
COMMUNICATION | doi:10.20944/preprints202212.0558.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: SMN; SMA; plasma membrane; ABCA1; cholesterol
Online: 29 December 2022 (09:13:39 CET)
The deficiency of Survival Motor Neuron (SMN) protein causes Spinal Muscular Atrophy (SMA), a rare neuromuscular disease that affects different organs. SMN is a key player in RNA metabolism regulation. An intriguing aspect of SMN function is its relationship with plasma membrane-associated proteins. Here, we provide a first demonstration that SMN affects the ATP-binding cassette transporter A1, (ABCA1), a membrane protein critically involved in cholesterol homeostasis. In human fibroblasts, we showed that SMN associates to ABCA1 mRNA, and impacts its subcellular distribution. Consistent with the central role of ABCA1 in the efflux of free cholesterol from cells, we observed a cholesterol accumulation in SMN-depleted human fibroblasts. These results were also confirmed in a SMA type I patient-derived fibroblasts. These findings not only validate the intimate connection between SMN and plasma mem-brane-associated proteins, but also highlight a contribution of dysregulated cholesterol efflux in SMA pathophysiology.
CASE REPORT | doi:10.20944/preprints202207.0045.v1
Subject: Medicine And Pharmacology, Endocrinology And Metabolism Keywords: Diabetic Foot Ulcer; Amniotic Membrane Allograft
Online: 4 July 2022 (09:32:17 CEST)
Management of diabetic foot ulcers (DFUs) presents challenges to even the most experienced wound care providers. Because of the chronic, non-healing nature of many DFUs, advances in the treatment and care of this disease process are particularly relevant. This case study aims to report the efficacy of the application of dehydrated amniotic membrane allograft (DAMA) to a diabetic foot ulcer. The patient in this study is a 44-year-old male who presented with an aggressive infection on his right foot, which resulted in an open wound of 18 months duration. This patient received weekly applications of dual-layer DAMA over seven weeks. Upon examination at the initial application, the wound was classified as a Wagner grade 3 with necrosis of the underlying muscle. Upon inspection at the final visit, the wound was closed entirely. The results that were shown include improvements in the size, depth, edges, necrotic tissue amount, and epithelization of the wound. This case study demonstrates that the ap-plication of DAMA has the potential to augment the body’s natural DFU healing response; however, future nonrandomized and randomized controlled trials are needed to establish its efficacy further.
ARTICLE | doi:10.20944/preprints202012.0815.v1
Subject: Chemistry And Materials Science, Analytical Chemistry Keywords: Membrane Chemical Regeneration; Phosphoric Acid; Clarification
Online: 31 December 2020 (13:45:51 CET)
Various techniques have been used to “clean-up” industrial phosphoric acid: precipitation, flotation, activated charcoal or clay treatment. To address membrane processes potential in phosphoric acid clarification process, this study explores the advantage of membrane techniques as new route for phosphoric acid clarification in an eco-efficient way through the use of “regenerated spent membrane”. Regeneration of the spent membranes was performed on of 0.15 m2 active area regeneration. These membrane samples were used to study the phosphoric acid clarification at a laboratory scale. They were immersed in an oxidizer for at most seven days. The samples were characterized systematically before immersion in an oxidant media. In this study, the potential to regenerate spent membranes and application of this media to clarify the 29% P2O5 phosphoric acid was demonstrated. This study shows, by tests that the reverse osmosis (RO) membranes achieve an abatement of 70% and 65% for solids and organic materials, respectively. These positive results will pave the way for implementing these membranes phosphoric acid treatment process. Moreover, besides being economically advantageous, the use of the spent membrane is likely an environmentally friendly route (no waste, no organic solvent and effluent to be regenerated later on).
REVIEW | doi:10.20944/preprints202012.0569.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: AMD; Biomaterials; electrospinning; membranes; Bruch's membrane
Online: 23 December 2020 (07:23:19 CET)
Abstract: Age-related macular degeneration (AMD) is the leading cause of central blindness in developed countries. It affects people mainly over the age of 50 years. It is a disease of the macula, an area of the retina responsible for sharp central vision. It particularly affects the Bruch’s membrane (BM); a layer in the retina that acts as the basement upon which retinal pigment epithelial cells (RPE) attach and survive. The pathology of AMD is not fully understood, but age is considered the main risk factor. There are two forms; nonexudative, leading to the end-stage of the disease, called nonexudative (or dry) AMD (90% of cases) where fatty deposits called drusen form under the RPE on top of the BM lifting off the RPE, and neovascular (or wet) AMD (10% of cases) where abnormal new blood vessels grow and push through the BM, bleeding in and disrupting the RPE. Neovascular AMD is well controlled with regular antiangiogenic drug injections of anti-vascular endothelial growth factor (anti-VEGF) into the eye, whereas there is no current treatment for nonexudative AMD. Many research groups across the world are working on a treatment for nonexudative AMD. This review discusses the research currently being conducted including cell therapies, development of cell transplantation membranes, targeting other disease structures in affected retina (i.e. drusen), and drug delivery to the retina using nanoparticles. Finally, we include our research contributing to the field; developing a bioactive membrane intended to function two-fold: target diseased structures and transplant healthy RPE to the desired area.
ARTICLE | doi:10.20944/preprints202009.0531.v1
Subject: Biology And Life Sciences, Cell And Developmental Biology Keywords: polystyrene; tissue culture; cell membrane stability
Online: 23 September 2020 (03:46:57 CEST)
Unanticipated errors in scientific research data can be attributed to the unwarranted assumption of uniformity in the polystyrene surface that is ubiquitously used in tissue culture flasks and dishes. We have shown that when adherent cells are subjected to fluid shear force, equivalent to rinsing the culture with a balanced salt solution, cells on some areas of the polystyrene surface will immediately rupture while still adherent on the surface. This heterogeneity on the polystyrene surface can cause unexpected variability in experimental results and in replicating experiments among labs. In this paper a novel quantitative method is described to measure the degree of heterogeneity on the polystyrene surface of tissue culture flasks. The results show significant variation among several brands of tissue culture flasks as well as large variability within the production lot of a manufacturer. The assay method involves loading the cells with a fluorescent marker that is released upon membrane rupture. Cell membrane rupture also causes the loss of marker proteins used in Westernblots. This novel assay method can be used to monitor the batch consistency and the manufacturing process of flasks and dishes. It may also be used to test new biomaterials.
HYPOTHESIS | doi:10.20944/preprints201904.0210.v2
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: regulation; membrane; glycerophospholipid; composition; chemical activity
Online: 31 October 2019 (04:39:47 CET)
Mammalian cells maintain the complex glycerophospholipid (GPL) class compositions of their various membranes within close limits because this is essential to their well-being or viability. Surprisingly, however it is still not understood how those compositions are maintained except that GPL synthesis and degradation closely coordinated. Here, we hypothesize that abrupt changes in the chemical activity of the individual GPL classes coordinate the synthesis and degradation, as well other homeostatic processes. A previously proposed model proposed that in cellular membranes only a limited number of “allowed” or optimal GPL glass compositions exist because they are energetically more favorable than the other compositions, i.e. they represent local free energy minima (Somerharju et al. 2009). This model, however, could not satisfactorily explain how the optimal compositions are sensed by the key homeostatic enzymes i.e., the rate-limiting synthetizing enzymes and the degrading enzymes (i.e., homeostatic phospholipases). We now propose that when the mole fraction of a GPL class exceeds an optimal one, its chemical activity abruptly increases, which (i) increases its propensity to efflux from the membrane thus making it susceptible for hydrolysis by homeostatic phospholipases, (ii) increases its potency to inhibit its own biosynthesis via a feedback mechanism, (iii) enhances its conversion to another GPL class via a novel process termed “head group remodeling” or (iv) enhances its translocation to other subcellular membranes. Accordingly, abrupt changes in the chemical activity of the individual GPL classes is proposed to regulate and coordinate those four processes maintaining GPL class homeostasis in mammalian cells.
COMMUNICATION | doi:10.20944/preprints201811.0539.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: nickel; HER; anion exchange membrane; electrolysis
Online: 22 November 2018 (05:30:57 CET)
Anion exchange membrane (AEM) electrolysis is hampered by two main issues: stability and performance. Focusing on the latter, this work demonstrates a highly active NiMo cathode for hydrogen evolution in AEM electrolysis. We demonstrate an electrolyzer performance of 1 A cm−2 at 1.9 V (total cell voltage) with a NiMo loading of 5 mg cm−2 and an iridium black anode in 1 M KOH at 50 °C, that may be compared to 1.8 V for a similar cell with Pt at the cathode. The catalysts developed here will be significant in supporting the pursuit of cheap and environmentally friendly hydrogen fuel.
ARTICLE | doi:10.20944/preprints201807.0371.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: molecular simulation; membrane separations; ion-transport
Online: 20 July 2018 (04:24:45 CEST)
In this report we have discussed the important role of molecular modeling, especially the use of the molecular dynamics method, in investigating transport processes in nanoporous materials such as membranes. With the availability of high performance computers, molecular modeling can now be used to study rather complex systems at a fraction of the cost or time requirements of experimental studies. Molecular modeling techniques have the advantage of being able to access spatial and temporal resolution which are difficult to reach in experimental studies. For example, sub-Angstrom level spatial resolution is very accessible as is sub-femtosecond temporal resolution. Due to these advantages, simulation can play two important roles: Firstly because of the increased spatial and temporal resolution, it can help understand phenomena not well understood. As an example, we discuss the study of reverse osmosis processes. Before simulations were used it was thought the separation of water from salt was purely a coulombic phenomenon. However, by applying molecular simulation techniques, it was clearly demonstrated that the solvation of ions made the separation in effect a steric separation and it was the flux which was strongly affected by the coulombic interactions between water and the membrane surface. Additionally, because of their relatively low cost and quick turnaround (by using multiple processor systems now increasingly available) simulations can be a useful screening tool to identify membranes for a potential application. To this end, we have described our studies in determining the most suitable zeolite membrane for redox flow battery applications. As computing facilities become more widely available and new computational methods are developed, we believe molecular modeling will become a key tool in the study of transport processes in nanoporous materials.
ARTICLE | doi:10.20944/preprints201807.0108.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Zein; nanocomposite membrane; adsorption; wastewater; RB19
Online: 6 July 2018 (08:01:59 CEST)
The present work demonstrates the new nanofiber mats prepared through co-electrospinning of two different polymers i.e. corn protein namely Zein and Nylon-6. The composite nanofiber membrane was used as an effective adsorbent material for the removal of toxic reactive dye i.e. Reactive Blue 19 (RB 19) from water solution. These co-electrospun nanofibers had good mechanical strength compared to zein nanofibers alone. Experimental results suggested that zein/nylon nanofibers have greater potential for total removal of RB19 at room temperature within 10 min of contact time from aqueous solution. The maximum capacity was found to be 70 mg/g of nanofibers. The mechanism of RB19 removal on proposed nanofibers is mainly through hydrogen bond and electrostatic means.
REVIEW | doi:10.20944/preprints202301.0420.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: Cryptococcus; extracellular protease; biofilm, secretory vesicles; hypoxia; hydrolytic enzyme; homeostasis; transcription factors; membrane permeases; membrane transporters
Online: 24 January 2023 (03:08:39 CET)
In this review, we present several extracellular proteases, enzymes, membrane permeases, and transporters as essential accessories proteins for nutrient assimilation, conservation, and transportation as determined by nutrient repletion or depletion. As an obligate aerobic pathogen, it is crucial for invading Cryptococcus (C.) neoformans to negotiate its adaptation to human internal organs like the brain and spinal cord, where the oxygen level is low compared to peripheral organs. Besides, essential metals like copper and iron are important cofactors to functional proteins; however, these metals are not usually freely available to invading human pathogens. Again, the phagolysosome low pH with glucose paucity, internal temperature, immune response, and complex extracellular matrixes are challenging environments that must be circumvented by C. neoformans in the systemic tissues for survival, adaptation, and infection in humans. We review extensive works on several extracellular proteases, enzymes, membrane permeases and transporters orchestrated by different transcription factors and present these proteins as weapons needed to outwit systemic resistance to invading pathogens. Lastly, we examine the extracellular secretory vesicles of C. neoformans as “an exosomal virulence bag” that harbours urease, laccase, phosphatase, and capsular components as additional secretory weapons for tissue invasion and persistence.
ARTICLE | doi:10.20944/preprints202309.0201.v1
Subject: Engineering, Chemical Engineering Keywords: Proton exchange membrane (PEM); poly(vinyl) alcohol membrane; proton conductivity; proton conductivity measurement; pH measurement; fuel cells
Online: 5 September 2023 (02:57:05 CEST)
In this research the possibility of using pH change to measure proton conductivity of proton exchange membranes (PEM) or else known as polymer electrolyte membranes are tested with using an experimental setup prepared by using pH meters. PEMs are an important part of the fuel cells and proton conductivity of the PEMs are one of the most important properties of the PEMs. Also, proton conductivity is the one of the biggest limiting factors of fuel cells thus it is important to measure the proton conductivity of the PEMs while trying new polymers or new types of membranes. But as current measurement methods do not have a standard and can be separated into mainly two different measurement methods which are Electron Impedance Spectroscopy (EIS) and Ion Exchange Capacity (IEC). EIS gives clearer results, but it needs an impedance analyzer machine, platinum electrodes and setup so this cannot be possible for every researcher due to its economical aspect. For IEC it is basically a titration method to see acid groups in the polymer or polymer matrix which are directly responsible for proton conductivity so this can show an indirect measurement of proton conductivity. But as for this one drawback are firstly this one is an indirect measurement and secondly needs overnight bath in solution can take long times. So, the possibility of using pH can be easier and both from time and economical aspect if it can be proven the give a direct relationship between pH change and proton conductivity.
ARTICLE | doi:10.20944/preprints202111.0067.v2
Subject: Medicine And Pharmacology, Pharmacology And Toxicology Keywords: Ih current, lamotrigine, HCN channels, theta rhythm, local field potentials, IPSCs, membrane excitability, action potential, membrane resonance.)
Online: 5 November 2021 (11:31:29 CET)
Theta oscillations generated in hippocampal (HPC) and cortical neuronal networks are involved in various aspects of brain function, including sensorimotor integration, movement planning, memory formation and attention. Disruptions of theta rhythms are present in individuals with various disorders, including epilepsy and Alzheimer’s disease. Theta rhythm generation involves a specific interplay between cellular (ionic) and network (synaptic) mechanisms. HCN channels are theta modulators, and several medications are known to enhance their activity. We investigated how different doses of lamotrigine (LTG), an HCN channel activator, and antiepileptic and neuroprotective agent, would affect hippocampal theta rhythms in acute HPC slices (in vitro) and anaesthetized rats (in vivo). Whole-cell patch clamp recordings revealed that LTG decreased GABAA-fast transmission in CA3 and CA1 cells, in vitro. In addition, LTG directly depressed CA3 and CA1 pyramidal neuron excitability. These effects were partially blocked by ZD 7288, a selective HCN blocker, and are consistent with decreased excitability associated with antiepileptic actions. Lamotrigine also depressed hippocampal theta oscillations in vitro, also consistent with its neuronal depressant effects. In contrast, it exerted an opposite, enhancing effect, on theta recorded in vivo. The contradictory in vivo and in vitro results indicate that LTG increases ascending theta activating medial septum/entorhinal synaptic inputs that over-power the depressant effects seen in hippocampal neurons. These results provide new insights into LTG actions and indicate an opportunity to develop more precise therapeutics for the treatment of dementias, memory disorders and epilepsy.
REVIEW | doi:10.20944/preprints202110.0447.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: UPR; IRE1; PERK; ATF6; lipid bilayer stress; ER stress; secretory pathway; hydrophobic mismatch; membrane thickness; membrane stiffness
Online: 29 October 2021 (07:57:29 CEST)
The endoplasmic reticulum (ER) is the major site of membrane biogenesis in most eukaryotic cells. As the entry point to the secretory pathway, it handles more than 10.000 different secretory and membrane proteins. The membrane insertion of proteins, their folding, and ER exit are affected by the lipid composition of the ER membrane and its collective membrane stiffness. The ER is also a hotspot of lipid metabolism for membrane lipids including sterols, glycerophospholipids, ceramides and neural storage lipids. The unfolded protein response (UPR) bears an evolutionary conserved, dual sensitivity to both protein folding-imbalances in the ER lumen and aberrant compositions of the ER membrane, referred to as lipid bilayer stress (LBS). Through transcriptional and non-transcriptional mechanisms, the UPR upregulates the protein folding capacity of the ER and balances the production of proteins and lipids to maintain a functional secretory pathway. In this review, we discuss how UPR transducers sense unfolded proteins and LBS with a particular focus on their role as guardians of the secretory pathway.
REVIEW | doi:10.20944/preprints202310.1071.v1
Subject: Medicine And Pharmacology, Pulmonary And Respiratory Medicine Keywords: extracorporeal membrane oxygenation; coagulation; immunothrombosis; viscoelastic tests
Online: 17 October 2023 (11:22:47 CEST)
Extracorporeal membrane oxygenation (ECMO) is used for the management of severe respiratory and cardiac failure, as well as bridge to definite treatment or transplantation. ECMO associated coagulopathy (EAC) is a frequent complication leading to high rates of thrombosis or severe haemorrhage, contributing to morbidity and mortality of patients. Understanding the pathophysiology of EAC is substantial for effectively managing patients on ECMO. We analyse the underlying mechanism of EAC and discuss the monitoring of coagulation profile, combining the viscoelastic point of care assays with the conventional coagulation laboratory tests.
REVIEW | doi:10.20944/preprints202308.0495.v1
Subject: Engineering, Bioengineering Keywords: polymer membrane; biofouling; hemofilter; CRRT; nanoparticles; nanocomposites
Online: 7 August 2023 (10:46:57 CEST)
In a blood purification technique continuous renal replacement therapy called CRRT , a porous hollow-fiber polymeric membrane is exposed to prolonged contact with blood. In that condition, like with any other submerged filtration membrane, hemofilter loses its properties over time and use which results in a rapid decline in flux. The most significant reason for this loss is the formation of a biofilm. Protein, blood cells and bacterial cells attach to the membrane surface in complex and fluctuating processes. Anticoagulation allows for longer patency of vascular access and a longer lifespan of the membrane. Other preventive measures include modification of the membrane itself. In this article, we focused on the role of nanoadditives in the mitigation of bio-fouling. Nanoparticles such as graphene, carbon nanotubes, silica effectively change surface properties towards more hydrophilic, affect pore size and distribution, decrease protein adsorption and damage bacteria cells. As a result, membranes modified with nanoparticles show better flow parameters, longer lifespan and increased hemocompatibility.
ARTICLE | doi:10.20944/preprints202304.0241.v1
Subject: Biology And Life Sciences, Cell And Developmental Biology Keywords: buccopharyngeal membrane; choanal atresia; mouth; Xenopus laevis
Online: 12 April 2023 (04:47:09 CEST)
The mouth is a central feature of our face, without it we could not eat, breathe, nor communicate. A critical and early event in mouth formation is the creation of a “hole” which connects the digestive system and the external environment. This hole, which has also been called the primary or embryonic mouth in vertebrates, is initially covered by a 1-2 cell layer thick structure called the buccopharyngeal membrane. When the buccopharyngeal membrane does not rupture it impairs early mouth functions and may also lead to further craniofacial malformations. Using a chemical screen in an animal model (Xenopus laevis) and genetic data from humans, we determined that Janus kinase 2 (Jak2) could have a role in buccopharyngeal membrane rupture. We have determined that decreased Jak2 function, using antisense morpholinos or a pharmacological antagonist, caused a persistent buccopharyngeal membrane as well as the loss of jaw muscles. Surprisingly, we observed that the jaw muscle compartments were connected to the oral epithelium that is continuous with the buccopharyngeal membrane. Severing such connections resulted in buccopharyngeal membrane buckling and persistence. We also noted puncta accumulation of F-actin, an indicator of tension, in the buccopharyngeal membrane during perforation. Together the data has led us to a hypothesis where muscles are required to exert tension across the buccopharyngeal membrane, and such tension is necessary for its perforation.
ARTICLE | doi:10.20944/preprints202211.0358.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: GDGT; archaea; membrane; Sulfolobus; isoprenoids; caldariellaquinone; terbinafine
Online: 18 November 2022 (13:44:15 CET)
Cellular membranes are essential for compartmentalization, maintenance of membrane permeability and fluidity in all three domains of life. Archaea belong to the third domain of life and have a distinct phospholipid composition. Membrane lipids of archaea are ether-linked molecules, specifically dialkyl glycerol diethers (DGDs) and glycerol dialkyl glycerol tetraethers (GDGTs). Terbinafine has been proposed as an inhibitor of GDGT biosynthesis in Archaea based on radiolabel incorporation studies. Here, we have studied the early cellular responses of the archaeon Sulfolobus acidocaldarius to terbinafine whose membrane is mostly composed of the membrane-spanning GDGTs. Depletion of GDGTs and an accompanying accumulation of DGDs upon treatment with terbinafine was growth phase and dose dependent. Additionally, a major shift in the saturation of caldariellaquinones was observed, resulting in the accumulation of unsaturated molecules. Transcriptomic data indicated that terbinafine primarily targets the respiratory complex along with genes involved in motility, fatty acid metabolism and GDGT cyclization. Combined, these findings suggest that respiratory stress is the preliminary response of S.acidocaldarius to terbinafine while targeting multiple proteins involved in isoprenoid biosynthesis and saturation.
REVIEW | doi:10.20944/preprints202103.0473.v1
Subject: Medicine And Pharmacology, Immunology And Allergy Keywords: Pterygium; Platelet-rich membrane; Surgery; Ocular; Repair
Online: 18 March 2021 (10:59:34 CET)
Pterygium is a common ocular disease caused by abnormal cellular proliferation leading to abnormal fibrovascular growth of the conjunctiva. The main treatment is surgical removal; however, despite the improvement of surgical techniques and development of adjuvant therapies, postoperative recurrence, which can be as high as 89%, remains a challenge. Currently, pterygium excision with conjunctival autograft remains the preferred surgical technique to decrease recurrence, especially when combined with ciclosporin eye drops. Nevertheless, there is no gold standard surgical technique to prevent pterygium recurrence. Therefore, this review aims to assess the safety, effectiveness and, applicability of platelet-rich fibrin membrane for primary pterygium surgery and assess its possible benefits in resource-limited settings.
CASE REPORT | doi:10.20944/preprints202010.0244.v1
Subject: Medicine And Pharmacology, Cardiac And Cardiovascular Systems Keywords: HOCM; SAS; Subaortic Membrane; LVOTO; ASH; SAM
Online: 12 October 2020 (13:27:11 CEST)
Hypertrophic obstructive cardiomyopathy (HOCM) is an autosomal dominant disorder leading to left ventricular outflow tract obstruction (LVOTO). It can present with chest pain, syncope, breathlessness, or in some cases sudden cardiac death. Primarily, it is diagnosed based on echocardiographic findings but cardiac computed tomography (CT) or cardiac magnetic resonance imaging (MRI) can be helpful in selected cases. In this case report, we discuss a case of a young-aged female patient previously diagnosed as HOCM and presented with chest pain, shortness of breath, and palpitations. Her echocardiography revealed severe asymmetrically hypertrophied left ventricle (LV) with normal function and systolic anterior motion of the mitral valve was present and a subvalvular aortic membrane was also seen. The computed tomography (CT) was also performed showing severe asymmetrical hypertrophied and thickened trileaflet tricommissural aortic valve with no calcification or significant valvular aortic stenosis but there was a subaortic membrane (concentric only sparing anteriorly). The presence of subaortic membrane with HOCM is a rare finding and it can be a diagnostic challenge and untreated cases are susceptible to progressive heart failure and worsening of the symptoms by further increasing left ventricular outflow tract obstruction (LVOTO). A thorough investigation and planning before surgical intervention is required to achieve optimal results.
ARTICLE | doi:10.20944/preprints201904.0087.v1
Subject: Chemistry And Materials Science, Polymers And Plastics Keywords: thermoplastic polyurethane; foaming; perforated structure; membrane; filtration
Online: 8 April 2019 (11:24:16 CEST)
The way in which a perforated structure is formed has attracted much interest in the porous membrane research community. This novel structure gives materials an excellent antifouling property as well as a low operating pressure and other benefits. Unfortunately, the current membrane fabrication methods usually involve multi-step processes and the use of organic solvents or additives. Our study is the first to offer a way to prepare perforated membrane by using a physical foaming technique with CO2 as the blowing agent. We selected thermoplastic polyurethane (TPU) as the base material because it is a biocompatible elastomer with excellent tensility, high abrasion resistance, and good elastic resilience. Various processing parameters, which included the saturation pressure, the foaming temperature, and the membrane thickness, were applied to adjust the TPU membrane’s perforated morphology. We proposed a possible formation mechanism of the perforated membrane. The as-prepared TPU membrane had good mechanical properties with a tensile strength of about 5 MPa and an elongation at break above 100%. Such mechanical properties make this novel membrane usable as a self-standing filter device. In addition, its straight-through channel structure can separate particles and meet different separation requirements.
ARTICLE | doi:10.20944/preprints201811.0359.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Carbon; nanofiber; membrane; urease; biomolecules; water treatment
Online: 15 November 2018 (11:08:43 CET)
Development of carbon nanomaterials for adsorption thus removal of organic pollutants from water is a progressive research subject. In this regard, carbon nanomaterials with bifunctionality towards polar and non-polar or even amphiphilic undesired materials is indeed attractive for further study and implementation. Here, we created carbon buckypaper adsorbents comprising amphiphilic (oxygenated amorphous carbon (a-COx)/graphite (G)) nanofilaments that can dynamically adsorb organic biomolecules (i.e. urease enzyme) and thus purify the wastewaters of relevant industries. Given the dynamic conditions of the test, the adsorbent was highly efficient in adsorption of the enzyme (88%) while permeable to water (2382 L.h-1.m-2), thus holds a great promise for further development and upscaling. A subsequent citric acid functionalization declined selectivity of the membrane to urease, implying the biomolecules adsorb mostly via graphitic domains rather than oxidized, polar amorphous carbon ones. The devised platform i.e. the urease functionalized buckypaper is optimally conductive (13 S.cm-1) and can be further employed as a biosensor. Accordingly, water treatment can be linked to biosensing via a nanostructured membrane.
REVIEW | doi:10.20944/preprints201709.0162.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: omega-3; PUFA; chemoresistance; membrane; DHA; EPA
Online: 29 September 2017 (18:32:40 CEST)
The efficacy of chemotherapy depends on sensitivity and intrinsic or acquired drug resistance of cancer cells. The n-3 long chain polyunsaturated fatty acids (n-3 LCPUFAs) are considered chemosensitizing agents and revertants of multidrug resistance by pleiotropic mechanisms. The specific mechanisms are not fully understood, but nowadays, it is widely accepted that there are a complex network of mechanisms, including alteration in gene expression, modulation of cellular proliferation and differentiation, induction of apoptosis, generation of reactive oxygen species and lipid peroxidation. A crucial mechanism in the control of cell drug uptake and efflux is related to n-3 LCPUFA influence on membrane lipid composition. The incorporation of docosahexaenoic acid in the lipid rafts produces significant changes in their physical-chemical properties affecting content and functions of transmembrane proteins, such as growth factors, receptors and ATP-binding cassette transporters. Of note, n-3 LCPUFAs often impact on the lipid compositions more in chemoresistant cells than in chemosensitive cells, suggesting their adjuvant role in cancer treatment.
ARTICLE | doi:10.20944/preprints201807.0612.v1
Subject: Engineering, Civil Engineering Keywords: translucent textile membrane roof, climate-based daylight modelling, daylight performance, energy conservation, translucent thermal insulation, multi-layer membrane
Online: 31 July 2018 (08:58:49 CEST)
Daylight usage in buildings improves visual comfort and lowers the final energy demand for artificial lighting. The question always occurs: how much conservation can you achieve? New upcoming or rare materials and constructions have a lack of information about their application. Therefore, the current work investigates the daylight performance of a multi-layer textile membrane roof with 2 300 m² on top of a sports hall. A translucent, thermal insulation with a glass fibre fleece between the roof membranes combines daylight usage and heating demand reduction. A sports hall with built year 2017 is selected as the case study building. The optical properties of the roof construction are measured. The (visual) light transmittance amounts to 0.72 % with a clean surface. An accordingly parametrized climate-based annual daylight modeling delivers daylight indicators for different construction scenarios. The results show that in comparison to only one glass facade, the additional translucent and thermally insulated membrane construction increases the annual daylight autonomy700/ continuous DA700 from 0/ 15 % to 1.5/ 38 %. In the roof covered areas of the sport field, this results in a reduction from 19.7 to 13.8 kWhel/m²/a electricity for the artificial lighting with dim control (30 % savings). Also, the influence of soiling on the light transmittance was determined with a relevant reduction of one layer about a factor 0.81. The novel results are of great value as a comparison and benchmark for planners and future buildings of similar type.
REVIEW | doi:10.20944/preprints202311.1682.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: Air Filter; Electrospinning; Polymeric Solutions; Polymeric Membrane; Fibers
Online: 27 November 2023 (11:34:42 CET)
The air is a fundamental element for the life on Earth. Rapid urbanization and industrialization release large amounts of pollutants (harmful gases, microorganisms, and particulate matter, among others) into the atmosphere, leading to health hazards. Air filtration is still the most used and promising technique for protecting air against pollutants. The quality and efficiency of filtering process are dependent of material used for the filter and other filter’s properties. Several methods can be used for manufacturing filters, one of them uses fibrous membranes obtained through electrospinning from polymeric solutions. Electrospinning is a technique that combines the application of an electrostatic field to a moving fluid which results in the fibers formation. Electrospun membranes are constituted by fibers that the sizes spread on submicro and or nanometric scales. This review focuses on fiber membranes obtained by electrospinning for filtration of particulate matter. It is addressed the effect of solution, processing and ambient parameters on the morphology and dimensional characteristics of fiber membranes. The basic principles of air filtration and test and characterization of filter performance are presented. The research progress on electrospun nanofibers as air filters in recent years is summarized and examined. Finally, conclusion and future perspectives in electrospun fibers for air filtration are provided and discussed.
BRIEF REPORT | doi:10.20944/preprints202309.1238.v1
Subject: Biology And Life Sciences, Life Sciences Keywords: IDO2; lung adenocarcinoma; A549; membrane localization; tyrosine-phosphorylation
Online: 19 September 2023 (04:21:41 CEST)
Indoleamine 2,3-dioxygenase 2 (IDO2) is a paralogue of IDO1, a tryptophan-degrading enzyme producing immunomodulatory molecules. However, the two proteins are unlikely to carry out the same functions. IDO2 shows little or no tryptophan catabolic activity and exerts contrasting immunomodulatory roles in a context-dependent manner, in both cancer and autoimmune diseases. The recently described potential non-enzymatic activity of IDO2 has suggested its possible involvement in alternative pathways resulting in either pro- or anti-inflammatory effects in different models. In a previous study on non-small cell lung cancer (NSCLC) tissues, we found that IDO2 expression, revealed at the plasma membrane level of tumor cells, was significantly associated with poor prognosis. In this study, the A549 human cell line, basally expressing IDO2, was used as an in vitro model of human lung adenocarcinoma to gain more insights on a possible alternative function of IDO2, different from the catalytic one. In these cells, immunocytochemistry and isopycnic sucrose gradient analyses confirmed the IDO2 protein localization in the cell membrane compartment, and immunoprecipitation of tyrosine-phosphorylated proteins revealed that IDO2 can be targeted by kinase activities. The different localization than the cytosolic one and the phosphorylation state are the first indications for the signaling function of IDO2, suggesting that the IDO2 non-enzymatic role in cancer cells is worthy of deeper understanding.
REVIEW | doi:10.20944/preprints202308.1184.v1
Subject: Biology And Life Sciences, Food Science And Technology Keywords: milk fat globule membrane; phospholipids; ganglioside; cholesterol; development
Online: 16 August 2023 (09:37:50 CEST)
Milk fat globule membrane (MFGM) is a complex tri-layer membrane that wraps droplets of lipids in milk. In recent years, it has attracted widespread attention due to its excellent bioactive functions and nutritional value. The milk fat globule membrane contains a diverse array of bioactive lipids, including cholesterol, phospholipids, and sphingolipids, which play pivotal roles in mediating the bioactivity of the milk fat globule membrane. We sequentially summarize the main lipid types in milk fat globule membrane in this comprehensive review and outline the characterization methods used to employed them. In this comprehensive review, we sequentially describe the types of major lipids found in the milk fat globule membrane and outline the characterization methods employed to study them. Additionally, we compare the structural disparities among glycerophospholipids, sphingolipids, and gangliosides, while introducing the formation of lipid rafts facilitated by cholesterol. The focus of this review revolves around an extensive evaluation of current research on lipid isolates from the milk fat globule membrane, as well as products containing milk fat globule membrane lipids, with respect to their impact on human health. Notably, we emphasize clinical trials encompassing a large number of participants. The summarized bioactive functions of milk fat globule membrane lipids encompass regulation of human growth and development, influence on intestinal health, inhibition of cholesterol absorption, enhancement of exercise capacity, and anti-cancer effects. By offering a comprehensive overview, the aim of this review is to provide valuable insights into the diverse biologically active functions exhibited by lipids in milk fat globule membrane.
ARTICLE | doi:10.20944/preprints202306.1152.v1
Subject: Engineering, Chemical Engineering Keywords: Dehumidification; natural gas; Nano composite membrane; TiO2 zeolite
Online: 15 June 2023 (13:22:37 CEST)
Some of Iran's gas resources are known as sour gas because one of the major by-products of this gas is water. In fact, natural gas is combined with water vapor in underground reservoirs. In some areas, the amount of water vapor in natural gas is so high that it can be used as a source of drinking water. However, it should be noted that water vapor in natural gas may exacerbate corrosion in pipes and industrial equipment, and the combustion of more natural gas produces high temperatures that can lead to the production of nitrogen oxides (NOx), which They are the cause of air pollution. This is while the processed gas has a standard percentage composition in which the amount of water has the lowest position. The removal of moisture from natural gas is due to the need to prevent the reduction of the calorific value of the gas and also to purify the gas in order to achieve the necessary standards for delivering gas to petrochemicals, industries and domestic uses. The main goal of this research is to investigate the influencing parameters on zeolite TiO2 nanocomposite membranes in order to absorb moisture from gas. For this reason, with the construction of a TiZ-V membrane as a standard membrane, the result of the initial evaluation of a suitable membrane for gas dehumidification was made, and this membrane was placed as a standard for measuring the effect of the manufacturing parameters in a way that in each stage of membrane construction It was found that it was different from standard TiZ-V membrane only in terms of one parameter. This type of investigation made it possible to determine the effect of various effective parameters in membrane construction on efficiency. The findings showed that increasing the concentration of SiO2 has the greatest effect on increasing the water flux of the membrane. According to the other findings of this study, the effect of increasing the reaction time of the vapor phase carrier has been to reduce the process of paternity selectivity loss at higher pressures. Although due to the safety limitation of the equipment to measure the efficiency of the membrane at pressures higher than 7 bar, this measurement was not carried out, but charts were presented regarding the state of the water in the water, which were a measure of the superiority of the water in the water in comparison to the gas in the water, which is the higher water in the water It is an indicator of the appropriateness of the membrane's efficiency at its corresponding pressure, so that the examination of the difference between these two graphs shows the possibility of using the membrane at higher pressures
ARTICLE | doi:10.20944/preprints202302.0186.v1
Subject: Chemistry And Materials Science, Chemical Engineering Keywords: flue gases; carbon dioxide; membrane; cascade; process design
Online: 10 February 2023 (07:50:32 CET)
The present paper deals with the complex study of the CO2 capture from combined heat power plant flue gases using the efficient technological scheme design – membrane cascade type of «Continuous Membrane Column». In contrast to well-known multi-step or multi-stage process designs, the cascade type of separation unit provides several advantages. That apparatus conceptually refers to the distillation columns. Here, the separation process is implemented in it by creating two counter current flows. In one of them is depleted by the high-permeable component in a continuous mode, meanwhile the other one is enriched. Taking into account, that the circulating flows rate overcome the withdrawn ones, there is a multiplicative growth in separation efficiency. A comprehensive study of the CO2 capture using membrane cascade type of «Continuous Membrane Column» includes the determination of optimal membrane material characteristics, the sensitivity study of the process and feasibility evaluation. It was clearly demonstrated that proposed process provides the efficient CO2 capture, which meets the modern requirements in terms of CO2 content (≥ 95 mol.%), recovery rate (≥ 90 %) and residual CO2 concentration (≤ 2 mol.%). Moreover, it was observed, that it is possible to process CO2 with purity up to 99.8 mol.% at the same recovery rate. This allows use of this specific process design in the CO2 pretreatment operations in the production of high-purity carbon dioxide.
REVIEW | doi:10.20944/preprints202207.0108.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: membrane curvature; molecular dynamics; simulations; BAR domain; trafficking
Online: 7 July 2022 (04:19:42 CEST)
Eukaryotic cells contain membranes with various curvatures, from the near-plane plasma membrane to the highly curved membranes of organelles, vesicles, and membrane protrusions. These curvatures are generated and sustained by curvature-inducing proteins, peptides, and lipids, and describing these mechanisms is an important scientific challenge. In addition to that, some molecules can sense membrane curvature and a thereby be trafficked to specific locations. The description of curvature-sensing is another fundamental challenge. Curved lipid membranes and their interplay with membrane-associated proteins can be investigated with molecular dynamics (MD) simulations, given the right tools. Various methods for simulating curved membranes with MD are discussed here, including tools for setting up simulation of vesicles, and methods for sustaining membrane curvature. The latter are divided into methods that exploit scaffolding virtual beads, methods that use curvature-inducing molecules, and methods applying virtual forces. The variety of simulation tools allow the researcher to closely match the conditions of experimental studies of membrane curvatures.
ARTICLE | doi:10.20944/preprints202102.0204.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Lipidome; High Five insect cells; Membrane proteins; Biomembranes
Online: 8 February 2021 (12:23:09 CET)
The lipid composition of biomembranes influence the properties of the lipid bilayer as well as that of the proteins. In this study, the lipidome and the lipid/protein ratio of membranes from High FiveTM insect cells overexpressing mouse P-glycoprotein was characterized. This provides a better understanding of the lipid environment in which P-glycoprotein is embedded, and thus of its functional and structural properties. The relative abundance of the distinct phospholipid classes and their acyl chain composition was characterized. A mass ratio of 0.57 +/- 0.11 phospholipids to protein was obtained. Phosphatidylethanolamines are the most abundant phospholipids, followed by phosphatidylcholines. Membranes are also enriched in negatively charged lipids (phosphatidylserines, phosphatidylinositols and phosphatidylglycerols), and contain small amounts of sphingomyelins, ceramides and monoglycosilatedceramides. The most abundant acyl chains are monounsaturated, with significant amounts of saturated chains. The characterization of the phospholipids by HPLC-MS allowed identification of the combination of acyl chains, with palmitoyl-oleoyl being the most representative for all major phospholipid classes except for phosphatidylserines, which are mostly saturated. A mixture of POPE:POPC:POPS in the ratio 45:35:20 is proposed for the preparation of simple representative model membranes. The adequacy of the model membranes was further evaluated by characterizing their surface potential and fluidity.
HYPOTHESIS | doi:10.20944/preprints202012.0657.v1
Subject: Biology And Life Sciences, Anatomy And Physiology Keywords: monophyly; progenotes; membrane evolution; origin of biological systems
Online: 25 December 2020 (12:29:28 CET)
Cells occupy a prominent place in the history of life on planet Earth. The central role of cellular organization is observed by the fact that “cellular life” is often used as a synonym for life itself. Thus, most characteristics used to define cells overlap with the ones used to define life. Notwithstanding, new scenarios about the origin of life are bringing alternative views to describe how cells may have evolved from the open biological systems named progenotes. Here, using a logical and conceptual analysis, we re-evaluate the characteristics used to infer a single origin for cells. We argue that some evidences used to support cell monophyly, such as the presence of elements from both the translation mechanism and the universality of the genetic code, actually indicate a unique origin for all “biological systems”, a term used to define not only cells, but also virus and progenotes. Besides, we present evidence that at least two biochemical pathways as important as (i) DNA replication and (ii) lipid biosynthesis may not homologous between Bacteria and Archaea. The identities observed between the proteins involved in those pathways along representatives of these two ancestral Domains are too low to indicate common genic ancestry. Altogether these facts can be seen as an indication that cellular organization has possibly evolved two or more times and that LUCA (the Last Universal Common Ancestor) might not have existed as a cellular entity. Thus, we aim to consider the possibility that different strategies acquired by biological systems to exist, such as viral, bacterial and archaeal were originated independently from the evolution of different progenote populations.
REVIEW | doi:10.20944/preprints202009.0513.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: PIP2; membrane dynamics; disease; actin dynamics; phosphoinositides; signaling
Online: 22 September 2020 (09:04:28 CEST)
In this review we summarize the recent development in understanding the role of PIP2 in cellular function and signaling. We first discuss the effect of PIP2 on actin binding proteins addressing the mechanism of the actin cytoskeletal dynamics such as polymerization or depolymerization of the filamentous network or the coupling to membrane to generate forces. Next, we outline the role of PIP2 in membrane dynamics. We summarized how the membrane organization depends upon PIP2 in the presence of ions or transmembrane proteins that are sensitive to membrane curvature. We discuss how clathrin coated pits interact with adaptor proteins during the endocytosis process, which is facilitated by PIP2. Finally, we discuss the role of PIP2 in cell signaling and diseases.
ARTICLE | doi:10.20944/preprints202008.0529.v2
Subject: Biology And Life Sciences, Biophysics Keywords: membrane potential; Nernst; Bernstein; action potential; propagation; theory
Online: 9 September 2020 (09:24:15 CEST)
Man has always been interested in animal electricity, which seems to be measured in every living cell. He has been fascinated by trying to elucidate the mechanisms by which this potential is created and maintained. Biology is the science that seeks to explain this mystery. Biology is based on basic sciences such as physics or chemistry. The latter, in turn, make systematic use of mathematics to measure, evaluate and predict certain phenomena and to develop "laws" and models that are as general as possible while respecting, as closely as possible, observations and facts. The Nernst equation was one of the pillars of electrochemistry. Biology also uses this same equation as one of the indispensable bases for the computation of membrane potential. Man has established a cellular model that highlights this equation in several forms. However, we are going to show by various means that this model is inadequate or even inapplicable.
ARTICLE | doi:10.20944/preprints202007.0655.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: dialysis membrane; ectosomes; exosomes; FTIR; infrared spectroscopy; purification
Online: 27 July 2020 (00:46:38 CEST)
Recent years brought great focus in the field of development of extracellular vesicles (EVs) based drug-delivery systems. Considering possible applications of EVs as a drug carriers the isolation process is a crucial step. To solve problems related with EV isolation, we created and validated a new EVs isolation method – Low Vacuum Filtration (LVF) and compared it with two commonly applied procedures - differential centrifugation (DC) and ultracentrifugation (UC). EVs isolated from endothelial cells culture media have been characterized by a) transmission electron microscopy (TEM) b) nanoparticle tracking analysis (NTA), c) western blot and d) Fourier-Transform Infrared Spectroscopy (FTIR). Additionally, the membrane surface have been imaged with Environmental Scanning Electron Microscopy (ESEM). We showed that LVF is reproducible and efficient method for EVs isolation form conditioned media. Additionally, we observed correlation between ATR-FTIR spectra quality and the EVs and proteins concentration. ESEM imaging confirmed that actual pore diameter are close to the values calculated theoretically. LVF method is an easy, fast and inexpensive EVs isolation method which allows for isolation of both ectosomes and exosomes from high volume sources with good repeatability. We think that it could be an efficient alternative for commonly applied methods.
ARTICLE | doi:10.20944/preprints202007.0059.v1
Subject: Biology And Life Sciences, Biophysics Keywords: plasma membrane; rafts; microemulsion; phase-separation; domain size
Online: 5 July 2020 (10:09:41 CEST)
It is widely, but not universally, believed that the lipids of the plasma membrane are not uniformly distributed, but that "rafts'' of sphingolipids and cholesterol float in a "sea'' of unsaturated lipids. The physical origin of such heterogeneities is often attributed to a phase coexistence between the two different domains. We argue that this explanation is untenable for several reasons. Further we note that the results of recent experiments are inconsistent with this picture. However they are quite consistent with an alternate explanation, namely that the plasma membrane is an emulsion of the two kinds of regions. To show this, we briefly review a simplified version of this theory and its phase diagram. We also explicate the dependence of the predicted domain size on four physical parameters. Among them are the spontaneous curvature of the membrane and its bending modulus and surface tension. Taking values of the latter two from experiment, we obtain domain sizes for several different cell types that vary from 58 to 88 nm.
ARTICLE | doi:10.20944/preprints202002.0008.v1
Subject: Engineering, Chemical Engineering Keywords: ceramic membrane; combination process; microfiltration; optimization; recovery efficiency
Online: 3 February 2020 (03:58:04 CET)
The aim of this study is to evaluate the optimal conditions of membrane filtration process. Both laboratory test and pilot-scale test were conducted to examine a treated water on blending water. The water sample were prepared by blending a raw water and the effluent water filtered through an organic membrane. The optimal efficiency in the treatment of water quality at the lab-scale test was generated under conditions of flux at 2.0 m3/m2∙day, the blending ratio of 4:1, and the optimal dosage of coagulant at 20 ppm. The pilot-scale test resulted in that the optimal efficiency was obtained under conditions of flux at 2.0 m3/m2∙day and the blending ratio of 6.0:1. However, the different results between lab-scale and pilot-scale tests on the optimal dosage of coagulant implied that it is difficult to achieve the stable condition of process operation at the low level of coagulant. In summary, the results indicated that, in the combination process of organic membrane and ceramic membrane, the recovery efficiency was achieved above the level of 98.4 %. Compared to 92.1 % in a single organic membrane process, the combination process is 6.3 % more efficient than the single one. This combination process of water treatment lead to stable recovery rates by the optimal input of dosage, less pollution load to water, and a stabilized filtration system.
ARTICLE | doi:10.20944/preprints201906.0061.v1
Subject: Chemistry And Materials Science, Analytical Chemistry Keywords: new, sulbatamol sulphate, membrane electrode , utilizing for determination
Online: 7 June 2019 (13:49:13 CEST)
A new sulbatamol sulphate SBS membrane electrode was prepared that utilizing for its determination ; depend on the forming of the association complex ion of sulbatamol sulphate by the phosphotungstate counter anion deposed in poly vinyl chloride PVC polymer, by use a (Di-n- Octyl Phenyl Phthalate)(Dopp) as the plastizier substance, in membrane.The features properties as well as the behavior of it .The new electrode have been elaborated. The concentrations of medicine by utillizing This sensor show a fast, stable, near-Nernstian response in the range (1x10-1-1x10-6) mol/ L were determined with correlation coefficient of about (r = 0.9991) and with of a relative standard about 0.416 additionally deviation relative standard error of 1.710 %.pot The nernast linearity slop was founded and it is equal to 28.9 mV/decade and the detection limit was 4.1 x 10-6 mol/ L.The electrode selectivity coefficient Ki,j was calculated, in the existence of several interferences cations with confirmed medicine solutions. It was found the pH range response is in the range of (3 -7), with the response time of (30 – 116) sec. for various concentrations at room temperture , the lifetime for electrode was found to be more than 21 days. The electrode was successfully used for potentiometric limitation of sulbatamol sulphate in several pharmaceutical drugs by using direct potentiometry.
ARTICLE | doi:10.20944/preprints201903.0068.v2
Subject: Chemistry And Materials Science, Chemical Engineering Keywords: germanium; supported liquid membrane; transport; Cyanex 923; modeling
Online: 29 May 2019 (04:54:50 CEST)
A transport process was studied from an aqueous solution containing oxalic acid and 100 mg/L Ge using a flat sheet supported liquid membrane (FSSLM) system. Cyanex 923 immobilized in a polytetrafluoroethylene membrane was employed as a carrier. The solution chemistry and related diagrams were applied to study the transport of germanium. The effectual parameters such as oxalic acid, carrier concentration, and strip reagent composition were evaluated in this study. Based on the results, the oxalic acid concentration of 0.075 mol/L and the carrier concentration of 20 %v/v were the condition in which the efficient germanium transport occurred. Among strip reagents, NaOH (0.04-0.1 mol/L) had the best efficiency to transport germanium through the SLM system. Furthermore, the permeation model was obtained to calculate the mass transfer resistances of the membrane (Δm) and feed (Δf) phases. According to the results, the values of 1 and 1345 s/cm were evaluated for Δm and Δf, respectively.
ARTICLE | doi:10.20944/preprints201810.0551.v1
Subject: Engineering, Chemical Engineering Keywords: RMM; membrane modules; modelling; material exchanger; permeation experiments
Online: 24 October 2018 (05:57:34 CEST)
Hydrogen is a promising energy carrier, exploitable to extract energy from fossil fuels, biomasses as well as intermittent renewable energy sources and its generation from fossil fuels with CO2 separation at the source is one of the most promising pathway for fossil fuels utilization. This work is focused on a particular configuration, called Reformer and Membrane Module (RMM), which alternates stages of Steam Reforming (SR) reaction with H2 separation stages to overcome the thermodynamic limits of the conventional SR. The configuration has numerous advantages with respect to the more studied and tested membrane reactors and has been tested on a pilot scale during a pilot-scale research project. Although the numerous modelling works appeared in the literature, the design features of the material exchanger (in the so-called RMM architecture) of different geometrical configurations have not been developed and the mass transfer correlations, capable of providing design tools useful for such membrane modules, are not available. The purpose of this work is therefore to apply a physical-mathematical model of the mass transfer, in three different geometries, considering both concentration polarization and membrane permeation, in order to: i) simulate the cited experimental results, ii) estimate the scaling-up correlations for the “material exchange modules”; iii) identify the mass transfer limiting regime in relation to the gas mass flow rate.
ARTICLE | doi:10.20944/preprints201810.0520.v1
Subject: Chemistry And Materials Science, Analytical Chemistry Keywords: MIMS; monochloramine; FTICR; chemical ionization; in-membrane reaction
Online: 23 October 2018 (05:44:42 CEST)
Membrane Inlet Mass Spectrometry (MIMS) was used to analyze monochloramine solutions (NH2Cl) and ammonia solutions in a compact FTICR. Chemical ionization enables identification and quantification of the products present in the permeate. The responses of protonated monochloramine and ammonium increase linearly with the solution concentration. The enrichments were respectively 1.2 and 5.5. Pervaporation is dependent on pH and only the basic form of ammonia NH3 pervaporates through the membrane. Unexpectedly, the small ammonia molecule permeated very slowly. It could be due to interactions with water molecules inside the membrane that create clusters. Moreover, NH2Cl solutions, in addition to the NH3Cl+ signal, presented a strong NH4+ signal at m/z 18.034 . Ammonia presence in the low-pressure zone before ionization is probable as NH4+ was detected with all the precursors used, particularly CF3+ and trimethylbenzene that presents a proton affinity higher than monochloramine. Ammonia may be formed inside the membrane due to the fact that NH2Cl is unstable and may react with the water present in the membrane. Those results highlight the need for caution when dealing with chloramines in MIMS and more generally with unstable molecules.
ARTICLE | doi:10.20944/preprints201711.0080.v1
Subject: Chemistry And Materials Science, Surfaces, Coatings And Films Keywords: PVDF membrane; coagulation bath temperature; polymer molecular weight
Online: 14 November 2017 (10:48:54 CET)
The global polyvinyldene flouride market is estimated to reach $937,278.5 thousand by 2019, therefore to develop new membranes and gain pioneering ideas, which could create innovative business opportunities, a fundamental knowledge about membrane properties fabricated from recent commercially available PVDF polymers is highly mandatory. In this study, we successfully prepared nine non-woven supported PVDF membranes using a phase inversion precipitation method starting from a 15 wt% PVDF solution in N-methyl-2-pyrrolidone. Various membrane morphologies were obtained by using (1) PVDF polymers with diverse molecular weight in a range from 300.000 Da to 700.000 Da and (2) different temperatures of the coagulation bath (20, 40, and 60 ±2°C) used for the films precipitation. Environmental Scanning Electron Microscope (ESEM) was used for surface and cross-section morphologies characterization. Atomic Force Microscope (AFM) was employed to investigate surface roughness, while Contact Angle (CA) instrument was used for membranes wettability studies. Fourier Transform Infrared Spectroscopy (FTIR) results show that the fabricated membranes are formed by a mixture of TGTG’ chains in α phase crystalline domains and all-TTTT trans planar zigzag chains characteristic to β phase. Moreover, generated results indicate that the phases content and membrane morphologies depend on the polymer molecular weight and conditions used for the membranes preparation. The diversity of fabricated membranes could be applied by the End User Industries for different applications.
REVIEW | doi:10.20944/preprints201706.0046.v1
Subject: Engineering, Chemical Engineering Keywords: Reverse osmosis; Membrane fouling; Fouling indices; Predicting models
Online: 9 June 2017 (11:04:40 CEST)
REVIEW | doi:10.20944/preprints202307.1238.v1
Subject: Engineering, Chemical Engineering Keywords: thorium removing; thorium recovery, thorium recycling; thorium separation, thorium transport; thorium separation; thorium membrane separation; thorium membrane concentration; thorium determination
Online: 18 July 2023 (13:36:38 CEST)
Although a slightly radioactive element, thorium is considered very toxic because its various species, which reach the environment, can constitute an important problem for the health of the population. The present paper aims to expand the possibilities of using membrane processes in the removal, recovery and recycling of thorium from industrial residues reaching the municipal waste processing platforms. The paper includes a short introduction on the interest shown for this element, a weak radioactive metal, followed by highlighting of some common (domestic) uses. In a distinct but concise part, the bio-medical impact of thorium is presented. The classic technologies for obtaining thorium are concentrated in a single schema, and then the speciation of thorium is presented with an emphasis on the formation of hydroxo-complexes and complexes with common organic reagents. The determination of thorium has been highlighted both on the basis of its radioactivity, but especially through methods that call for extraction followed by an established electrochemical, spectral or chromatographic method. Membrane processes are presented based on the electrochemical potential difference, rapidly presenting barro-membrane processes, electrodialysis, liquid membranes and hybrid processes. A separate sub-chapter is devoted to proposals and recommendations for the use of membranes in order to achieve some progress in urban mining for the valorization of thorium.
ARTICLE | doi:10.20944/preprints202311.1285.v1
Subject: Medicine And Pharmacology, Medicine And Pharmacology Keywords: antimicrobial activity; molecular dynamics; membrane; peptide; structure-activity relationship
Online: 21 November 2023 (07:27:05 CET)
In our previous work, we demonstrated the potential of the amphiphilic cyclic peptide [W4R4] as a promising antimicrobial agent. The extensive data accumulated on the antimicrobial activity of this peptide and its homologs presented an opportunity to unravel the molecular mechanisms governing their action and establish crucial structure-activity relationships (SAR). To achieve this, we employed a comprehensive approach involving peptide synthesis, in vitro biological testing, and molecular modeling to systematically analyze the SAR of a series of cyclic peptides derived from the [W4R4] scaffold. Minimal modifications were introduced to the original peptide by incorporating either one aromatic hydrophobic residue (W) or one polar positively charged residue (R) while maintaining the sequential W/R arrangement. Additionally, we introduced an "intermediate" substitution by incorporating 2,5-diketopiperazine (DKP), possessing both aromatic and polar properties, into the macrocycle [W4R4] between the W and R residues. Notably, this study marked the first synthesis and evaluation of the [W4R4(DKP)] peptide. Structural, dynamic, hydrophobic, and membrane-binding properties of four cyclic peptides ([W4R4], [W5R4], [W4R5], [W4R4(DKP)]) were explored using molecular dynamics simulations within a DOPC/DOPG lipid bilayer that mimics the bacterial membrane. The results obtained revealed distinct SAR profiles for all peptides, enabling the establishment of correlations between their antimicrobial activity and structural/dynamic parameters. These parameters included the degree of conformational plasticity, the depth of immersion into the bi-layer, and the population of the membrane binding mode characterized by the embedding of the hydrophobic peptide pattern into the acyl chain region of lipids. In particular, the peptide [W4R5] exhibited an optimal "activity/binding to the bacterial membrane" pattern. This work highlights the significance of our multidisciplinary approach in efficiently deciphering finely regulated SAR profiles for a series of homologous peptides with diverse activities. Furthermore, this research provides a solid foundation for the rational design of novel antimicrobial peptides.
REVIEW | doi:10.20944/preprints202309.0802.v1
Subject: Biology And Life Sciences, Cell And Developmental Biology Keywords: endothelial cells; cell membrane repair; dysferlin; annexins; cardiovascular diseases
Online: 13 September 2023 (05:43:59 CEST)
Endothelial cells are the crucial inner lining of blood vessels, pivotal in vascular homeostasis and integrity. However, these cells are perpetually subjected to a myriad of mechanical, chemical, and biological stresses that can compromise their plasma membranes. A sophisticated repair system involving key molecules, such as calcium, annexins, dysferlin, and MG53, is essential for maintaining endothelial viability. These components orchestrate complex mechanisms, including exocytosis and endocytosis, to repair membrane disruptions. Dysfunctions in this repair machinery, often exacerbated by aging, are linked to endothelial cell death, subsequently contributing to the onset of atherosclerosis and the progression of cardiovascular diseases (CVD) and stroke, major causes of mortality in the United States. Thus, identifying the core machinery for endothelial cell membrane repair is critically important for understanding the pathogenesis of CVD and stroke and developing novel therapeutic strategies for combating CVD and stroke. This review summarizes the recent advances in understanding the mechanisms of endothelial cell membrane repair. The future directions of this research area are also highlighted.
REVIEW | doi:10.20944/preprints202308.1668.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: penetrating cations; mitochondria; membrane; uncoupler; phospholipid bilayer; anti-cancer
Online: 24 August 2023 (03:48:51 CEST)
As mitochondria are negatively charged organelles, penetrating cations are used as a part of the chimeric molecules to deliver the specific compounds into mitochondria. However, unmodified penetrating cations affect different aspects of cellular physiology as well. In this review we have attempted to summarize the data about side effects of the commonly used natural (e.gberberine) and artificial (e.g. tetraphenylphosphonium, rhodamine, methylene blue) penetrating cations on cellular physiology. For instance, it was shown that such types of molecules can (1) facilitate proton transport across membranes; (2) react with redox groups of respiratory chain; (3) induce DNA damage; (4) interfere with pleiotropic drug resistance; (5) disturb membrane integrity (6) inhibit the enzymes. Also, the products of the biodegradation of penetrating cations can be toxic. As penetrating cations accumulate in mitochondria, their toxicity is mostly due to the mitochondrial damage. Mitochondria of certain types of cancer cells appear to be especially sensitive to penetrating cations. Here we discuss the molecular mechanisms of the toxic effects and the anti-cancer activity of the penetrating cations.
REVIEW | doi:10.20944/preprints202308.0430.v1
Subject: Biology And Life Sciences, Anatomy And Physiology Keywords: chorioallantoic Membrane (CAM); angiogenesis; organotypic culture; engineered 3D scaffold
Online: 7 August 2023 (03:01:19 CEST)
We are witnessing the revival of the CAM model, which was already used in the past by some authors studying angiogenesis and anti-cancer drugs, that now offers a refined model to fill, in the translational meaning, the gap between in vitro-in vivo studies. It can be used for a wide range of purposes, from testing cytotoxicity, pharmacokinetics, tumorigenesis, invasion, to action mechanisms of molecules, and validation of new materials from tissue engineering research. CAM model is easy to use with a fast outcome and makes experimental research more sustainable since allowing to replace, reduce and refine pre-clinical experimentation ("3Rs" rules ). This re-view aims to highlight some unique potentials that CAM-assay presents; in particular, the authors intend to use in the next future the CAM model to verify, in a microenvironment comparable to in vivo conditions, albeit simplified, the angiogenic ability of functionalized 3D constructs to be used in regenerative medicine strategies in the recovery of skeletal injuries of critical size (CSD) that do not repair spontaneously. For this purpose, organotypic cultures will be planned on sever-al CAMs set up in temporal sequence: a sort of organ model for assessing CSD conducted in the CAM bioreactor, rather than in vivo.
ARTICLE | doi:10.20944/preprints202308.0086.v1
Subject: Chemistry And Materials Science, Analytical Chemistry Keywords: chromium(VI); polymer inclusion membrane; optode; FTIR; quantitative analysis
Online: 2 August 2023 (02:25:31 CEST)
A partial least squares (PLS) quantitative chemometric method based on the analysis of the MID-FTIR spectrum of polymer inclusion membranes (PIMs) used for the extraction of Cr(VI) from aqueous media is developed. The system previously optimized considering the variables membrane composition, extraction time, and pH, is characterized in terms of its adsorption isotherm, distribution coefficient, extraction percent and enrichment factor. A Langmuir type adsorption behavior with KL = 21.99 L/mg, qmax = 0.242 mmol/g and 0<RL<1, indicates that metal adsorption is favorable. The characterization of the extraction reaction is performed as well showing an 1:1 Cr(VI):Aliquat 336 ratio, in agreement with solvent extraction data. The principal component analysis (PCA) of the PIMs revels a complex pattern, which is satisfactorily simplified and related to Cr(VI) concentrations through the use of a variable selection method (iPLS) in which bands in the ranges 3451–3500 cm-1 and 3751–3800 cm-1 are chosen. The final PLS model including the 100 wavelengths selected by iPLS and 10 latent variables shows excellent parameter values with RMSEC: 3.73115, RMSECV: 6.82685, Bias: -1.91847e-13, CV Bias: 0.185947, R2 Cal: 0.98145, R2 CV: 0.940902, recovery%: 104.02 ± 4.12 (=0.05), sensitivity%: 0.001547 ppb, γ: 3.8 ppb, γ- 1: 0.6 ppb-1, selectivity: 0.0155, linear range: 5.8–100 ppb, LD: 1.9 ppb, and LQ: 5.8 ppb. The developed PIM sensor is easy to implement as it requires few manipulations and reduced number of chemical compounds in comparison to other similar reported systems.