ARTICLE | doi:10.20944/preprints201902.0208.v1
Subject: Engineering, Civil Engineering Keywords: cellular concrete, cellular material, foam concrete, foam material, crushable foam, crushing strength, mechanical property, foam modulus
Online: 21 February 2019 (13:12:40 CET)
Foam concrete is a highly cellularized cementitious material that undergoes extensive plastic deformation when loaded to failure. Under compression, the foam structure gets progressively crushed at a steady stress stage such that a substantial amount of energy is dissipated. Understanding foam concrete crushing behavior is of special importance for its engineering applications such as energy absorber, but the current studies are insufficient to define material properties for design of field applications. This study characterizes the crushing strength and foam modulus of samples with penetration test and resonant frequency test, respectively. A four-phase crushing behavior is observed. The yield strength and plateau strength are identified to characterize the foam crushing. Using the experimental inputs, the modulus-strength constitutive equations are then established. These findings are useful for expanding the knowledge of normal concrete to studies on foam concrete, as well as design of applications.Foam concrete is a highly cellularized cementitious material that undergoes extensive plastic deformation when loaded to failure. Under compression, the foam structure gets progressively crushed at a steady stress stage such that a substantial amount of energy is dissipated. Understanding foam concrete crushing behavior is of special importance for its engineering applications such as energy absorber, but the current studies are insufficient to define material properties for design of field applications. This study characterizes the crushing strength and foam modulus of samples with penetration test and resonant frequency test, respectively. A four-phase crushing behavior is observed. The yield strength and plateau strength are identified to characterize the foam crushing. Using the experimental inputs, the modulus-strength constitutive equations are then established. These findings are useful for expanding the knowledge of normal concrete to studies on foam concrete, as well as design of applications.
ARTICLE | doi:10.20944/preprints201902.0207.v1
Subject: Engineering, Civil Engineering Keywords: cellular material; cellular concrete; foam concrete; foam material; mechanical property; Young’s modulus; foam modulus
Online: 21 February 2019 (13:12:08 CET)
Foam concrete is a construction material with controllable low strength and untraditional physical properties. Its highly crushable nature leaves it a niche as an engineered energy-absorbing material in many value-added applications; however, fundamental understanding of the material properties is crucial. As foam concrete is highly cellularized and ductile, conventional concrete testing methods such as compression test are insufficient to characterize the key material attributes of foam concrete, especially when the foam density is low. The resonant frequency test (ASTM C215) is specified for evaluating dynamic Young’s modulus of normal concrete. Inspired by the non-destructive feature of this test, we investigate the possibility of using the resonant frequency test to continuously monitor the modulus build-up of foam concrete with age. For the representativeness of the samples, three variables are considered in material design—bulk density ranging from 0.4 to 1.2 g/cm3, water to cementitious materials ratio of 0.42 and 0.47, and fly ash replacement of 10 and 30% by weight of cement. After examining the different vibration modes, the fundamental transverse frequency is determined most suitable for interpreting the foam modulus. The experimental results demonstrate good accuracy of using this approach for the measurement of different samples. It is also confirmed that, for a given foam concrete, the foam modulus can be predicted by knowing the foam density and solid modulus of its base cement paste, which provides an important insight for the further studies and real applications of foam concrete.
ARTICLE | doi:10.20944/preprints202303.0471.v1
Subject: Physical Sciences, Other Keywords: Foam; Node; Film; Marangoni flow; Plateau Border; Bubble; Reflux; Foam fractionation
Online: 28 March 2023 (03:54:44 CEST)
Marangoni flow in foam fractionation in the lamellar film for the interior and exterior of a micro-foam was investigated. The three-dimensional node-film-Plateau Border system was modeled using computational fluid dynamics. The importance of the surfactant concentration of the foam fractionation column and air-liquid interface mobility on the Marangoni velocity in the film was emphasized. The study found that an increase in surfactant concentration in the reflux column significantly increases the Marangoni velocities. Additionally, a mobile interface results in a higher Marangoni flow, while a rigid interface leads to less intensive flow. The behavior of the Marangoni flow in both interior and exterior foam was explored, revealing that the flow in exterior foam has different behavior due to the presence of the wall, which reduces the Marangoni velocity compared to interior films.
ARTICLE | doi:10.20944/preprints202307.1027.v1
Subject: Biology And Life Sciences, Insect Science Keywords: spittlebug; cercopid; aphrophora; walker; biochemistry; foam
Online: 17 July 2023 (10:37:14 CEST)
The aim of this study was to analyze the chemical composition of nymphal envelopes (foam) collected from hemipterans from spittlebug belonging to the species Aphrophora alni (Hemiptera family Aphrophoridae). Foam was collected in Poland in the Mazowieckie Voivodeship in 2020- 2022. Foam was collected from nymphs, feeding on young leaves of black alder trees (Alnus glutinosa), from 12 different areas. For the first time, the chemical composition of the foam produced by the spittlebug was quantitatively analyzed, identifying from 73.76 to 93.21 percent. The analyzed samples consisted mainly of a carbohydrate polymer similar in sugar unit composition to fucoidate isolated from brown seaweed. The most important sugar units identified were fucose (17.0 % - 35.6 % of the dry weight of the secretion), glucose (6.1 % - 16.2 %), mannose (1.5 % - 9.9 %), rhamnose (0.4 % - 1.3 %) and xylose (0.06 % - 0.1 %). In addition, various fatty acids, myo-inositol, pinitol, aliphatic hydrocarbons, waxes and aliphatic derivatives of 2(3H)-furanone were found. The collected foam contained from 0.05 % to 0.1 % of dry matter. Significant changes in the chemical composition of nymphal envelopes were found depending on the year of collection, which is probably strongly related to climate change.
ARTICLE | doi:10.20944/preprints202307.1360.v1
Subject: Chemistry And Materials Science, Chemical Engineering Keywords: Tannin; Furfuryl alcohol; Polyvinyl alcohol; Foam; Insole
Online: 19 July 2023 (16:17:43 CEST)
The exploitation of bio-based foams implies an increase in the use of renewable biological resources to reduce the rapid consumption of petroleum-derived resources. Both tannins and furfuryl alcohol are derived from forestry resources and are therefore considered as attractive precursors for the preparation of tannin-furanic foams. In addition, toughening modification of tannin-furanic foams using polyvinyl alcohol (PVOH) resulted in a more flexible network-like structure, which imparts excellent flexibility to the foams with acquirement of relative properties that are even close to those of polyurethane foams, which are the most used polymers for fabrication of insoles for athletes. In addition, the addition of PVOH did not affect the thermal insulation of the foams, resilience and elongation at break, while reducing the brittleness of the samples and improving the mechanical properties. Also the observation of the morphology of the foam indicated that the compatibility between PVOH and tannin-furanic resin is good, and the cured foam does not show fragmentation or collapse, while the bubble pore structure is uniform. The developed flexible foam derived from biomass resources endowed the foam good thermal insulation properties and high mechanical properties, and the samples exhibited suitable physical parameters to be used as flexible insoles for athletes.
ARTICLE | doi:10.20944/preprints201812.0191.v1
Subject: Engineering, Architecture, Building And Construction Keywords: polymer waste; polyurethane foam; leaching test; microstructure
Online: 17 December 2018 (10:47:59 CET)
In the European Union, the demand for polyurethane is continually growing. In 2017, the estimated production value of polyurethane was 700,400T, of which 27.3% is taken to landfill, which causes an environmental problem. In this paper the behaviour of various polyurethane foams from the waste of different types of industries will be analysed with the aim of assessing their potential use in construction materials. In order to this, the wastes were chemically tested by means of CHNS, TGA, and leaching tests. They were tested microstructurally by means of SEM. The processing parameters of the waste was calculated after finding out its granulometry and its physical properties i.e. density and water absorption capacity. In addition, the possibility of incorporating these wastes in plaster matrices was studied by determining its rendering in an operational context, finding out its mechanical resistance to flexion and compression at 7 days, its reaction to fire as well as its weight per unit of area and its thermal behaviour. The results show that in all cases, the waste is inert and does not undergo leaching. The generation process of the waste determines the foam’s microstructure in addition to its physical-chemical properties that directly affect building materials in which they are included, thus offering different ways in which they can be applied.
ARTICLE | doi:10.20944/preprints202306.1719.v1
Subject: Chemistry And Materials Science, Polymers And Plastics Keywords: coconut fatty acid distillate; rigid polyurethane foam; bio-based polyols; high open-cell content foam; thermal insulating material
Online: 25 June 2023 (05:41:11 CEST)
This study propounds a sustainable alternative to petroleum-based polyurethane (PU) foams aiming to curtail this nonrenewable resource's continued and uncontrolled use. Coconut fatty acid distillate (CFAD) and crude glycerol (CG), both wastes from vegetable oil processes, were utilized for bio-based polyol production for rigid PU foam application. The raw materials were subjected to catalyzed glycerolysis with alkaline-alcohol neutralization and bleaching. The resulting polyol possessed properties suitable for rigid foam application with an average OH number of 215 mg KOH/g, acid number of 7.2983 mg KOH/g, and Gardner color value of 18. The polyol was used to prepare rigid PU foam, and its properties were determined using FTIR, TGA/DTA, and UTM. Additionally, the cell foam morphology was investigated by scanning electron microscope (SEM) in which most of its structure revealed an open-celled network and quantified at 92.71% open cell content using pycnometric testing. The PU foam thermal and mechanical analysis results showed an average compressive strength of 70.59 kPa, thermal conductivity of 46.50 mWm-1K-1, and density of 32.79 kgm-3. These properties showed its applicability as thermal insulating foam, thus, demonstrating the potential use of CFAD and CG in commercial polyol and PU foam production.
ARTICLE | doi:10.20944/preprints202309.0304.v1
Subject: Engineering, Chemical Engineering Keywords: polyurethane foam; activated carbon; adsorption; lead; heavy metals
Online: 6 September 2023 (03:11:09 CEST)
This study presents a novel polyurethane-activated carbon composite (PACC) as an effective and sustainable adsorbent for treating lead-ion-contaminated waters. The PACC was characterized using SEM-EDX, FTIR, BET, XRD, and TGA to evaluate its physicochemical and thermal properties. Furthermore, the PACC was employed in an experimental column adsorption setup to investigate its adsorption performance and to develop a dynamic method suitable for industrial implementation. Parameters such as bed height (50, 100, 150 mm), flow rate (4, 6, 8 mL min-1), pH (2, 4, 6), and initial metal ion concentrations (10, 50, 100 mg L-1) were examined. The experimental data exhibited strong agreement with the Thomas and Yoon-Nelson models (R2 ≥ 0.96), indicating efficient adsorption mechanisms. Remarkably, the depleted adsorbent has the potential for facile regeneration without substantial loss in capacity. The PACC demonstrated excellent adsorption performance for lead ions in aqueous solutions in a fixed-bed column system. Thus, the novel PACC material holds potential for scalable application in industrial settings to address water pollution challenges, especially in regions with uncontrolled effluent discharge.
ARTICLE | doi:10.20944/preprints202309.0118.v1
Subject: Chemistry And Materials Science, Electrochemistry Keywords: platinum; nickel foam; electroless deposition; formic acid; oxidation
Online: 4 September 2023 (15:41:47 CEST)
Pt-coated Ni layer supported on Ni foam catalyst (denoted PtNi/Nifoam) was investigated for the oxidation of the formic acid (FAO) in acidic media. The prepared PtNi/Ni foam catalyst was studied as a function of the formic acid (FA) concentration at bare Pt and PtNi/Nifoam catalysts. The catalytic activity of the PtNi/Nifoam catalysts, studied on the basis of the ratio of the direct and indirect current peaks (jd)/(jnd) for the FAO reaction, showed values about 10 times higher compared to those on bare Pt, particularly at a low formic acid concentrations, reflecting the superiority of the former catalysts for the oxidation of FA to CO2. Ni foams provide a large surface area for the FOR while synergistic effects between Pt nanoparticles and Ni-oxy species layer on Ni foams contribute significantly to the enhanced oxidation of FA via the direct pathway, making it almost equal to the indirect pathway, particularly at low formic acid concentrations.
ARTICLE | doi:10.20944/preprints202207.0067.v1
Subject: Medicine And Pharmacology, Cardiac And Cardiovascular Systems Keywords: restenosis; foam cells; NLRP3 inflammasome; MAPK signaling pathway
Online: 5 July 2022 (08:15:38 CEST)
The accumulation of foam cells in arterial intima and the accompanied chronic inflammation are considered major causes of neoatherosclerosis and restenosis. However, both the underlying mechanism and effective treatment for the disease are yet to be uncovered. In this study, we combined transcriptome profiling of restenosis artery tissue and bioinformatic analysis to reveal that NLRP3 inflammasome is markedly upregulated in restenosis and that several restenosis re-lated DEGs are also targets of mulberry extract, a natural dietary supplement used in traditional Chinese medicine to improve liver vitality. Further pathway enrichment analysis identified MAPK signaling pathway to be involved in the inflammatory response of foam cells. Consistently, immunofluorescence microscopy shows co-localization of NLRP3 with CD68+ macrophages. We then evaluated the efficacy of mulberry extract in inhibiting both the formation of foam cells and their inflammatory response. We demonstrated that mulberry extract suppresses the formation of ox-LDL induced foam cells, possibly by upregulating the cholesterol efflux genes ABCA1 and ABCG1 to inhibit intracellular lipid accumulation. In addition, mulberry extract dampens NLRP3 inflammasome activation by stressing the MAPK signaling pathway. Collectively, our mecha-nistic and functional studies unveil the therapeutic value of mulberry extract in neoatherosclerosis and restenosis treatment by regulating lipid metabolism and inflammatory response of foam cells.
ARTICLE | doi:10.20944/preprints202106.0719.v1
Subject: Engineering, Automotive Engineering Keywords: foam; flocculation; FLO genes; Saccharomyces; fuel-ethanol; FLO8
Online: 30 June 2021 (08:59:57 CEST)
Many contaminant yeast strains able to survive inside fuel ethanol industrial vats show detrimental cell surface phenotypes, such as filamentation, invasive growth, flocculation, biofilm formation and excessive foam production. Previous studies have linked some of these phenotypes to the expression of FLO genes, and the presence of gene length polymorphisms causing the expansion of FLO gene size appears to result in stronger flocculation and biofilm formation phenotypes. We have performed here a molecular analysis of FLO1 and FLO11 gene polymorphisms present in contaminant strains of S. cerevisae from Brazilian fuel ethanol distilleries showing strong foaming phenotypes during fermentation. The size variability of these genes was correlated with cellular hydrophobicity, flocculation and highly foaming phenotypes in these yeast strains. Our results also show that deleting the major activator of FLO genes (the FLO8 gene) from the genome of a contaminant and highly foaming industrial strain avoids problematic foam formation, flocculation, invasive growth and biofilm production by the engineered (flo8∆::BleR / flo8Δ::kanMX) yeast strain. Thus, the characterization of highly foaming yeasts and the influence of FLO8 in this phenotype opens new perspectives for yeast strain engineering and optimization in the sugarcane fuel-ethanol industry.
ARTICLE | doi:10.20944/preprints202004.0534.v1
Subject: Engineering, Mechanical Engineering Keywords: bicycle; helmet; brain injury; EPS foam; impact; safety
Online: 30 April 2020 (14:10:36 CEST)
This study evaluates various safety aspects of standardized impacts that cyclists may suffer while wearing a bicycle helmet, by combining a partially validated finite element model of the cranio-cervical region and a newly developed bicycle helmet model. Under EN 1078 standardized impact conditions, the results of simulated impact tests show that the helmet can absorb 40% to 50 % of the total impact energy at impact velocities above 4 m/s. Further, based on a relationship between Head Injury Criterion and the risk of injury from field data, the results of the simulations suggest that minor injuries may occur at impact velocities of 10 km/h, serious injuries at 15 km/h, and severe injuries at 20 km/h. Fatal injuries will likely occur at impact velocities of 30 km/h and higher.
ARTICLE | doi:10.20944/preprints201906.0283.v1
Subject: Chemistry And Materials Science, Paper, Wood And Textiles Keywords: TEM; thermal degradation; wall paper; blowing agent; foam
Online: 27 June 2019 (06:29:11 CEST)
This study was conducted to improve the white index (WI) by preparing thermally expandable microspheres (TEMs) for wallpaper. The thermal properties, foam expansion ratio and WI were studied depending on the particle size of colloidal silica in the preparation of TEMs. As a result, the TEMs with small particles of colloidal silica showed the best results for whiteness and yellowing. Additionally, TGA results indicated that it was highly possible that colloidal silica with small particle sizes was physically or chemically attached to the surface of the TEMs that led to an improvement in whiteness at high temperatures.
ARTICLE | doi:10.20944/preprints202306.1825.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: thermo-photocatalysis; nickel foam; Ni doped TiO2; acetaldehyde decomposition
Online: 26 June 2023 (14:22:19 CEST)
Acetaldehyde decomposition was performed under heating at the temperature range of 25-125oC and UV irradiation on TiO2 doped by the metallic Ni powder and TiO2 supported on the nickel foam. Process was carried out in high temperature reaction chamber “The Praying MantisTM”, with simultaneous in situ FTIR measurements and UV irradiation. Ni powder was added to TiO2 in the quantity of 0.5 to 5.0 wt%. Photothermal measurements of acetaldehyde decomposition indicated, that the highest yield of acetaldehyde conversion on TiO2 und UV irradiation was obtained at 75oC. Doping of nickel to TiO2 did not increase its photocatalytic activity. Contrary to that, application of nickel foam as a support for TiO2 appeared to be highly advantageous, because increased decomposition of acetaldehyde from 31 to 52% at 25oC and then to 85% at 100oC by comparison with TiO2 itself. At the same time mineralisation of acetaldehyde to CO2 increased two times at the presence of nickel foam. However, oxidised nickel foam used as support for TiO2 was detrimental. Most likely, different mechanisms of electrons transfer between Ni-TiO2 and NiO-TiO2 occurred. Application of nickel foam greatly enhanced separation of free carriers in TiO2. As a consequence, high yields of the photocatalytic reactions were obtained.
Subject: Physical Sciences, Fluids And Plasmas Physics Keywords: Metal Foam; Porous Medium; Convection; Local Thermal Non-Equilibrium
Online: 15 August 2020 (10:04:38 CEST)
Metal foams are widely studied as possible tools for the enhancement of heat transfer from hot bodies. The basic idea is that a metal foam tends to increase significantly the heat exchange area between the hot solid body and the external cooling fluid. For this reason, this class of porous materials are considered as good candidates for an alternative to finned surfaces, with different pros and cons. Among the pros, we mention the generally wider area of contact between solid and fluid. Among the cons is the difficulty of producing different specimens with the same inner structure, with the consequence that their performance may be significantly variable. This paper will offer a survey of the literature with a focus on the main heat transfer characteristics of the metal foams. Then, a numerical simulation of the heat transfer at the pore scale level for an artificial foam with a spatially periodic structure will be discussed. Finally, these numerical results will be employed to assess the macroscopic modelling of the flow and heat transfer in a metal foam.
ARTICLE | doi:10.20944/preprints202002.0002.v1
Subject: Engineering, Architecture, Building And Construction Keywords: construction; rainwater harvesting; solar; spray foam; finger-jointed studs
Online: 3 February 2020 (03:04:44 CET)
The question of building sustainable in a geographical locality is inexorably linked to cost. In 2011, one of the authors built a sustainable house that was (at the time) the highest certified sustainable home based on the National Association of Home Builder’s standards for sustainable construction. This Texas house has been used for residential and research purposes for the past decade. In this case study, the authors evaluate components of the construction and their effectiveness as well as unseen secondary and tertiary effects. Some of the specific components discussed are home site placement; rainwater harvesting (100% of residential requirements); aerobic septic system; grid-tied solar array power; electric car charging; geothermal heating and cooling; reclaimed wood framing; spray foam installation; selection of windows, fixtures, and appliances; on-demand electric water heaters for guest areas; generator backups; and use of local items. Electric bills and water system improvements are discussed in detail, as improvements were made as part of residential and research requirements. This case study suggests that the financial outlay is worth the extra up-front costs if residents in this geographical area and climate will occupy the residence 7 years.
ARTICLE | doi:10.20944/preprints201910.0222.v1
Subject: Chemistry And Materials Science, Polymers And Plastics Keywords: 3D structure; gradient foam; additive manufacturing; CO2 foaming; copolymer
Online: 19 October 2019 (02:10:29 CEST)
Synthetic polymer-based gradient foams have considered as promising category of functionally graded materials with unique properties. In this study, the carbon dioxide (CO2) foaming technology has used for PET-PEN (Polyethylene Terephthalate - Polyethylene Naphthalate) copolymer towards porous functional materials with thermal insulation with reasonable mechanical strength. Through scanning electron microscope based morphological characterization, a potential to fabricate gradient foam structures with micro-pores has identified. It has shown that variation of post-foaming temperature can tune the pore size distribution although the very high post-foaming temperature tends to cause structural instability. Thermal measurement data set the limits of operation, confirmed by simultaneous differential scanning calorimeter and thermo-gravimetric analysis. Mechanical stress and thermal conductivity also has measured to find rationale of thermal insulation with reasonable mechanical strength and to elucidate the actual 3D grid foam of copolymer.
ARTICLE | doi:10.20944/preprints201901.0174.v1
Subject: Chemistry And Materials Science, Electronic, Optical And Magnetic Materials Keywords: high-$T_c$ superconductors; YBCO; foam; trapped fields; current flow
Online: 17 January 2019 (03:36:15 CET)
Superconducting foams of YBa$_2$Cu$_3$O$_y$ (YBCO) are proposed as trapped field magnets or supermagnets. The foams with an open-porous structure are light-weight, mechanically strong and can be prepared in large sample sizes. The trapped field distributions were measured using a scanning Hall probe on various sides of an YBCO foam sample after field-cooling in a magnetic field of 0.5 T produced by a square Nd-Fe-B permanent magnet. The maximum trapped field (TF) measured is about 400 G (77 K) at the bottom of the sample. Several details of the TF distribution, the current flow and possible applicatons of such superconducting foam samples in space applications, e.g., as active elements in flux-pinning docking interfaces (FPDI) or as portable strong magnets to collect debris in space, are outlined.
ARTICLE | doi:10.20944/preprints201806.0154.v1
Subject: Engineering, Energy And Fuel Technology Keywords: EOR; graphene oxide; CO2 foam; aquifer storage; mobility control
Online: 11 June 2018 (11:10:46 CEST)
Graphene oxide (GO), nanographene oxide (nGO) and partially reduced graphene oxide (rGO) have been studied as possible foam stabilizing agents for CO2 based enhanced oil recovery (EOR). GO was able to stabilize CO2/synthetic sea water foams. rGO was not able to stabilize foams likely due to the high reduction degree of the material. Particle size had a strong influence on foamability and stability. GO hydrophilicity increased as the particle size decreased and no foams were created when particle size was below 1 µm (nGO). GO brine dispersions showed immediate gel formation, which improved foam stability. Particle growth due to layer stacking was also observed. This mechanism was detrimental for foam formation and stabilization. nGO dispersed in synthetic sea water rapidly formed hydrogels and was not filterable. This work indicates that the particles studied are not suitable for CO2 EOR purposes.
ARTICLE | doi:10.20944/preprints202203.0167.v2
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: Superconducting foams; YBCO; microstructure; modelling parameters; foam cells; current flow
Online: 16 March 2022 (14:15:15 CET)
Superconducting YBa2Cu3Oy (YBCO) foams were prepared using commercial open-cell, polyurethane foams as starting material to form ceramic Y2BaCuO5 (Y-211) foams which are then converted into superconducting YBCO by using the infiltration growth process. For modelling the superconducting and mechanical properties of the foam samples, a Kelvin-type cell may be employed as a first approach like done in the literature for pure polyurethane foams. However, for a refined model of a superconducting foam sample, the real sample structure must be considered. Thus, a proper description of the specific microstructure of the superconducting YBCO foams is required. A variety of parameters including the cell size and shape, the window size and shape, the length and shape of the foam struts or ligaments and the respective angles of intersection are used to describe the real foam structure. To obtain a set of reliable data, YBCO foam samples were investigated using optical microscopy, SEM and electron backscatter diffraction (EBSD). The detailed investigation of the foam microstructure reveals not only the differences to the polymeric foams used as base material, but also gives insight to details of the infiltration growth process via the increased surface amount in a foam sample.
ARTICLE | doi:10.20944/preprints201906.0289.v1
Subject: Engineering, Civil Engineering Keywords: digital fabrication; 3D printing; foam concrete; mixture design; material testing
Online: 28 June 2019 (07:28:09 CEST)
3D-printing with foam concrete, which is known for its distinct physical and mechanical properties, has not yet been purposefully investigated. The article at hand presents a methodological approach for the mixture design of 3D-printable foam concretes and a systematic investigation of the potential application of this type of material in digital construction. Three different foam concrete compositions with water-to-binder ratios between 0.33 and 0.36 and having densities of 1100 to 1580 kg/m³ in the fresh state were produced with a pre-foaming technique using a protein-based foaming agent. Based on the fresh-state tests, including 3D-printing as such, an optimum composition was identified and its compressive and flexural strengths were characterised. The printable foam concrete showed compressive strength above 10 MPa and low thermal conductivity, which make it suitable for 3D-printing applications, while fulfilling both load-carrying and insulating functions.
ARTICLE | doi:10.20944/preprints202305.0076.v1
Subject: Engineering, Mechanical Engineering Keywords: Piezoresistivity; impact sensing; polyurethane foam; structural health monitoring (SHM); smart materials
Online: 2 May 2023 (09:48:25 CEST)
Smart flexible materials with piezoresistive property are increasingly used in sensors field. When embedded in structures, they would allow an in-situ structural health monitoring and damage assessment of impact loading such as crash, bird strikes and ballistic impacts. However, this could not be achieved without a deep characterization of the relation between piezoresistivity and mechanical behavior. The aim of this paper is to study the potential use of the piezoresistivity effect of a conductive foam made of a flexible polyurethane matrix filled with active carbon for integrated Structural Health Monitoring (SHM) and damage assessment applications. To do so, PolyUrethane Foam filled with Active Carbon, namely PUF-AC, are manufactured and tested under quasi-static compression tests and under Dynamic Mechanical Analyser (DMA) with in-situ measurement of its resistivity during tests. A relation is proposed for describing the evolution of the resistivity versus strain and stress. In addition, a demonstrative experiment of a PUF-AC sample subjected to low velocity impact assesses the interest of this type of materials for damage assessments.
ARTICLE | doi:10.20944/preprints202211.0012.v1
Subject: Engineering, Mechanical Engineering Keywords: syntactic foam; particle variation; flexural properties; volume fraction; scanning electron microscope
Online: 1 November 2022 (03:22:25 CET)
Syntactic foam has proven to be a good material with a strong structural strength. Understanding filler particle size variation is important in composite material formation especially in syntactic foam because of their numerous applications such as aerospace, marine and structural purposes. In this present work, the effects of particle variation in different sizes (20-24µm, 25-44µm, 45-49µm, and 50-60µm) on the mechanical properties of the syntactic foam composites with focus on flexural strength, modulus, and fracture surfaces were investigated. The particle sizes were varied into five volume fractions (5, 10, 15, 20, and 25vol%). The results shows that highest flexural strength is 89MPa at 5 vol% fraction of 50-60µm particles size variation which is 69% increase than the neat epoxy. This implies that the incorporation of HGM filler volume fraction and size variation has a strong effect on the flexural strength and bending modulus of syntactic foam. The microstructure of the fracture surfaces and the viscoelastic properties was determined and reported accordingly.
ARTICLE | doi:10.20944/preprints202205.0077.v1
Subject: Engineering, Industrial And Manufacturing Engineering Keywords: metallic foam; CFD; fixed-bed reactor; friction factor; heat transfer coefficient
Online: 6 May 2022 (13:49:16 CEST)
Open-cell metallic foams used as catalyst supports exhibit excellent transport properties. In this work, a unique application of metallic foam, as pelletized catalyst in a packed bed reactor, is examined. By using a wall-segment Computational Fluid Dynamics (CFD) setup, parametric analyses are carried out to investigate the influence of foam morphologies (cell size ϕ=0.45-3 mm and porosity ε=0.55-0.95) and intrinsic conductivity on flow and heat transport characteristics in a slender packed bed (N=Ddp=6.78) made of cylindrical metallic foam pellets. The transport processes have been modeled using an extended version of conventional particle-resolved CFD, i.e., flow and energy in inter-particle spaces are fully resolved, whereas porous-media model is used for the effective transport processes inside highly-porous foam pellets. Simulation inputs include the processing parameters relevant to Steam Methane Reforming (SMR), analyzed for low (Rep~100) and high (Rep~5000) flow regimes. The effect of foam morphologies on packed beds has shown that the desired requirements contradict each other, i.e., increase in cell size and porosity favor the reduction in pressure drop, however lowering the heat transfer efficiency. A design study is also conducted to find the optimum foam morphology of a cylindrical foam pellet at higher Rep~5000, which yields ϕ = 0.45, ε = 0.8. Suitable correlations to predict the friction factor and the overall heat transfer coefficient in a foam packed bed have been presented, which considers the effect of different foam morphologies over a range of particle Reynolds number, 100≤Rep≤5000.
ARTICLE | doi:10.20944/preprints201806.0339.v1
Subject: Engineering, Architecture, Building And Construction Keywords: post disaster housing; rapid assembly systems; foam filled sandwiches; modular construction;
Online: 21 June 2018 (12:52:55 CEST)
In this paper the development process of a deployable modular sandwich panelized system for rapid assembly building construction is presented, and its structural performance under some different action effects is investigated. This system, which includes an innovative sandwich panel and its integrated connections, can be used as structural walls and floors in quickly assembled post-disaster housing, as well as load bearing panels for pre-fabricated modular construction and semi-permanent buildings. Panels and connections are composed of a pneumatic fabric formwork, and two 3-D high-density polyethylene (HDPE) sheets as the skins, filled with high-density rigid Polyurethane (PU) foam as the core. HDPE sheets manufactured with a studded surface considerably enhance the stress distribution, buckling performance and delamination strength of the sandwich panel under various loading conditions. The load-carrying behaviour of the system in accordance with some ASTM standards is presented here. The results show the system satisfies the codes criteria regarding semi-permanent housing.
ARTICLE | doi:10.20944/preprints202306.1836.v1
Subject: Chemistry And Materials Science, Polymers And Plastics Keywords: Polypropylene; foam; upcycling; negative Poisson's ratio; auxetic materials; cellular structure; mechanical properties.
Online: 26 June 2023 (21:55:19 CEST)
In this work, a simple and environmentally friendly process combining low pressure (vacuum) and mechanical compression is proposed to convert recycled polypropylene (PP) foams (28 kg/m3) into low density foams (90-131 kg/m3) having negative tensile and compressive Poisson's ratios (NPR). The effect of processing conditions (vacuum time, temperature, and mechanical pressure) was studied. Based on the optimized conditions, the tensile Poisson’s ratio of the resulting auxetic foams reached −1.50, while the minimum compressive Poisson's ratios was −0.32 for the same sample. The foam structure was characterized via morphological analysis (SEM) to determine any changes related to the treatment applied. Finally, tensile and compressive properties (Young's modulus, strain energy, energy dissipation and damping capacity) are also presented and discussed. It was observed that the mechanical properties of the resulting auxetic foams were improved compared to the original PP foam (PP-O) for all tensile properties in terms of modulus (19.9 to 59.8 kPa), strength (0.298 to 1.43 kPa) elongation at break (28 to 77%), energy dissipation (14.4 to 56.3 mJ/cm3) and damping capacity (12 to 19%). Nevertheless, improvements were also observed under compression in terms of energy dissipation (1.6 to 3.6 mJ/cm3) and damping capacity (13 to 19%). These auxetic foams can find applications in sport and military protective equipment, as well as any energy mitigation system.
ARTICLE | doi:10.20944/preprints202301.0055.v1
Subject: Chemistry And Materials Science, Electrochemistry Keywords: acid washing; nickel foam; hydrogen evolution reaction; alkaline water electrolysis; electrode preparation
Online: 4 January 2023 (03:25:42 CET)
Nickel foam substrates are frequently utilised for renewable energy applications as porous 3D-substrates. Preparation of these substrates usually includes an acid washing step, however the degree to which this step affects the final electrochemical performance after spray coating a catalyst ink is unreported. Herein, we report the effect of acid washing through physicochemical and electrochemical characterisation. The electrochemical performance was determined by repeated measurements of catalyst-coated nickel foam substrates both with and without the initial step of acid washing. Acid washing increased current density by 17.9% for the acid treated, MoS2-coated nickel foam electrode. This increment was affiliated with an electrochemically active surface area which increased by 87.1%, where Tafel analysis indicated that the acid treated, MoS2-coated electrodes facilitates the initial water dissociation step of the hydrogen evolution reaction with greater ease. Similar effects were also discovered for acid treated PtIr(1:3)/C-coated nickel foam substrates, albeit with less pronounced effects. Stability was also improved where the degradation rate was reduced by 18.9% for the acid treated, MoS2-coated electrodes. This proves the utility of acid washing nickel foam electrodes.
ARTICLE | doi:10.20944/preprints201811.0049.v1
Subject: Chemistry And Materials Science, Polymers And Plastics Keywords: natural rubber latex foam; fire behavior; thermally thin materials; thermally thick materials
Online: 2 November 2018 (10:29:14 CET)
Fire behavior of natural rubber latex foam under different thickness conditions(d=1,2and 5cm)were explored though a little of experiments by using the self-built small scale experimental platform. It can be shown that the flame spread law of thermally thin and thermally thickness are different. Natural rubber latex foam with thickness of 2cm show higher fire risk, which value of flame spread rate, maximum flame height, maximum mass loss rate and maximum temperature is 0.00293m/s, 851.875mm, 1.83g/s, 948K,repectively.That may because the thickness of residue formed of thermally thick materials is larger than the thin one, obstructing the contact of the natural rubber latex foam with fresh air .In addition, a special phenomenon is noticed that during the second stage, the bottom unburned zone located in the four edges(thermally thin material) and middle player(thermally thick material).
ARTICLE | doi:10.20944/preprints201810.0182.v2
Subject: Engineering, Automotive Engineering Keywords: Detection unit; Extinguishing unit; IR; SMS; GSM module; Wireless module; LabVIEW; Foam
Online: 30 October 2018 (08:46:04 CET)
Fire accidents are causing a huge human death as well as economic losses throughout the world every year. But a novel fire detection and extinguishing system could reduce these losses to a great extent. We are proposing a cost effective and yet very efficient system which has been developed in our laboratory and evaluated while in operation. Our system consists of two units: detection unit and extinguishing unit. For detection purposes we used smoke, IR and temperature sensors. While for extinguishing purposes we used both foam and water. We used a PC to process and control our system through LabVIEW software of National Instrument, USA. The detection unit will send signal through a wireless module to PC if fire is detected. Then PC (LabVIEW) will process the signal and using relay module first of all the electric power and gas lines will be turned off. The extinguishing unit will then release foam or water to extinguish the fire. The system will send SMS to the predefined numbers using GSM module. Our system is location independent as it uses GSM and can be operated from remote location using wireless module. After performance evaluation it was found to be fast and reliable.
ARTICLE | doi:10.20944/preprints202305.0296.v1
Subject: Engineering, Energy And Fuel Technology Keywords: Metal-air batteries cell; electrode materials; open cell foam; replication process; effective conductivity
Online: 5 May 2023 (04:24:22 CEST)
The global context of research for new sustainable energy storage technologies makes it a very active sector with significant scientific and economic challenges. Indeed, due to the irregular development of renewable energies and the shutdown of traditional power facilities, it is difficult to maintain a stable balance in terms of supply and demand: energy storage can help in particular for substantial changes in the latter. Metal air batteries have a higher energy density and are safer than other available energy storage devices. Based on the existing and proven lead-acid battery technology, this paper proposed an open cell foam manufactured by the Excess Salt Replication process for use as an anode for lead-air battery cellsies with sulphuric acid as the electrolyte. This will save lead and reduce the battery weight. A 25% antimonial lead alloy was used to produce open cell foams with a cell diameter between 2 mm and 5 mm for the antimonial lead-air battery. Preliminary results of the effective electrical conductivity of self-discharged primary battery cells, measured experimentally, showed that all antimonial lead foam-air battery cellsies performed better than that made from the same dense non porous antimonial lead alloy. This is generally due to their important specific surface area where oxidation-reduction reactions took place. A correlation between the effective electrical conductivity and the cell diameter has been established and the highest conductivity was obtained with a cell diameter of 5mm. The feasibility of such an electrical system has been demonstrated.
ARTICLE | doi:10.20944/preprints202304.1001.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: Eclipta prostrata; gelatin; foam dressing; wound dressing; physical property; absorption; dehydration; pH environment
Online: 26 April 2023 (15:23:50 CEST)
Developing novel wound dressings containing medicinal plant extracts can have several potential benefits, including improving the therapeutic value of the dressings and reducing the cost of producing wound dressings. In this study, we prepared foam dressing containing Eclipta prostrata leaf extract and gelatin (Eclipta prostrata dressing). Chemical composition was verified using Fourier transform infrared spectroscopy (FTIR), and pore structure was obtained by scanning electron microscopy (SEM). The physical properties, including absorption and dehydration properties, were also evaluated. The chemical properties were measured to determine the pH environment after being submerged with Eclipta prostrata dressings. The results revealed that the Eclipta prostrata dressing had a pore structure with an appropriate pore size (313.25 ± 76.51 µm and 383.26 ± 64.45 µm for the Eclipta prostrata A and Eclipta prostrata B dressings, respectively). The Eclipta prostrata B dressing was more consistent porosity, resulting in a higher absorption capacity and faster dehydration rate. According to physical properties, the Eclipta prostrata B dressing is best used on low-exuding wounds. Furthermore, the Eclipta prostrata A and B dressings make a slightly acidic environment. Therefore, our foam dressing will not interfere wound healing process.
ARTICLE | doi:10.20944/preprints202108.0128.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: Carbon foam; multi walled carbon nanotubes; Graphene oxide; electrical; mechanical and thermal properties
Online: 5 August 2021 (08:36:50 CEST)
Multi-walled carbon nanotubes (MWCNTs) and graphene oxide (GO) reinforced carbon foam (CF) composite were prepared by direct pyrolysis of MWCNTs, GO and mesophase coal tar pitch. The effect of additive amount of the mixture of MWCNTs and GO on the microstruture and properties of carbon foam was analzyed by transmission electron miscroscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Four-probe resistance meter, universal testing machine, and laser thermal conductivity tester respectively. The result shows that MWCNTs and GO had significant impact on the microstructure of carbon foam. Futhermore, the electrical, mechanical and thermal properties of carbon foam composites were significantly enhanced by increasing the additive amount. Maximum compressive strenght of 19.2 MPa and Young’s modulus of 56.8 MPa of CF composite were observed. Similarly, Highest thermal conductivity of 30.91 W/m.K and electrical conductivity of 27.2 ×103 S/m were observed at 2 wt. % of MWCNTs-GO additive loading.
ARTICLE | doi:10.20944/preprints201901.0240.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: metal vacuum panel; vacuum Insulation Panel; energy; gas emission; foam concrete; honeycomb materials
Online: 23 January 2019 (10:27:49 CET)
This study examines whether gas is emitted from the materials used in the fabrication of metal vacuum panels or not and if emitted, their degree as time goes by. As experimental materials, metal sheets, foamed concrete as a core material, and polymer materials as a sealing material between metal sheets were selected. Experiments on the type and the degree of bending of metal materials showed that aluminum’s vacuum reaching time of 0.001 torr was at least 40 sec to 90 sec in its flat plate, but its vacuum reaching time increased from 3 times to 4.5 times in case of 90 ° and 135 ° bending state. For this reason, it is judged that stainless steel or steel material is suitable because aluminum is inadequate in terms of processability at the time of fabricating the metal vacuum panel. Also, vacuum arrival times and weight changes with increasing foam content of inorganic foamed concrete increased from 22,000 sec to 42,000 sec with increasing foaming rate and also, the weight change increased from 1.7% to 8%. Also, the experimental results on the type of honeycomb materials, the PE (polyethylene) with a vacuum reaching time of 30,000 sec and with a weight change of 0.5% and the PTFE (Poly-tetrafluoro ethylene) with a vacuum reaching time of 29,000 sec and with a weight change of 2.2% showed the optimum value.
ARTICLE | doi:10.20944/preprints201809.0074.v1
Subject: Chemistry And Materials Science, Polymers And Plastics Keywords: flexible polyurethane foam, flame retardant, bridged–DOPO compounds, microscale combustion analysis, thermal analysis
Online: 4 September 2018 (16:41:44 CEST)
In this work we have investigated the role of various additives (emulsifier, anti-dripping agent) and formulation procedure (pre- dispersion of solid additives in polyol via milling) which influence the flame retardancy of 6,6′-[ethan-1,2-diylbis(azandiyl)]bis(6H-dibenzo[c,e][1,2]oxaphosphin-6-oxid) (EDA-DOPO) containing flexible polyurethane foams. For comparison, the flame retardancy of two additional structurally analogues bridged 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) based compounds i.e. ethanolamine-DOPO (ETA-DOPO) and ethylene glycol-DOPO (EG-DOPO) were also evaluated together with EDA-DOPO in flexible PU foams of various formulations. The flame retardancy of three bridged-DOPO compounds depends on the type of PU formulation. For certain PU formulation containing EDA-DOPO, lower fire performance was observed. Addition of emulsifier and polytetrafluoroethylene (PTFE) to these PU formulations influenced positively the flame retardancy of EDA-DOPO/PU foams. In addition, dispersion of EDA-DOPO and PTFE via milling in polyol improved the flame retardancy of the PU foams. Mechanistic studies performed using pyrolysis combustion flow calorimetry (PCFC) and its coupling to FTIR showed no difference in the combustion efficiency of the bridged-DOPO compounds in PU foams. From these PCFC experiments we can conclude that these bridged-DOPO compounds and their decomposition products may work primarily in the gas phase as flame inhibitors. Physiochemical behavior of additives in PU formulation responsible for the improvement in the flame retardancy of PU foams was further investigated by studying the dripping behavior of the PU foams in UL 94 HB test. A high-speed camera was used to study the dripping behavior in the UL 94 HB test and results indicate a considerable reduction of a total number of melt drips and flaming drips for the flame retardant formulations. This reduction in melt drips and flaming drips during the UL 94 HB tests help PU foams achieve higher fire classification.
ARTICLE | doi:10.20944/preprints202309.0630.v1
Subject: Engineering, Energy And Fuel Technology Keywords: Metal foam distributor; Compression ratio; Limiting current density; Maximum power density; Serpentine channel; Uniform distribution
Online: 11 September 2023 (07:12:52 CEST)
This paper presents a comprehensive evaluation of metal foam employment within polymer electrolyte fuel cells (PEFCs) and compares it with conventional serpentine channels from both experiment viewpoints and computational fluid dynamics simulation. The experiments are designed to study the effects of material, area density, compression ratio, and final thickness of metal foam. Additionally, the influence of housing plate material and relative humidity (RH) is also tested for the first time. The results reveal that at RH=75-100%, the best distributor design is nickel foam with a compression ratio of 70%, a final thickness of 0.5mm, and SS-304 housing plate, which delivers 3110 mA cm-2 as limiting current density that is scarce in the literature. The PEFC with this foam distributor shows a 10% improvement in maximum power density and 45% in limiting current density compared to the serpentine channel case. While at RH=30%, the same foam flow field with a final thickness of 1mm is a superior option. The experiments also indicate that maximum power density increases by 23% as the compression ratio rises from 0 to 70%, while reducing final thickness from 1 to 0.5 mm causes a 19% enhancement in cell performance. Simulation results reveal that metal foam is more successful in evenly reactant distribution so that the average oxygen mass fraction at the cathode catalyst layer is increased by 38% in the metal foam case compared to the serpentine channel.
ARTICLE | doi:10.20944/preprints202308.0426.v1
Subject: Engineering, Energy And Fuel Technology Keywords: Gas injection; Water Alternating Gas; Foam Assisted Water Alternating Gas; Discrete Fracture Model; Fractured reservoirs
Online: 7 August 2023 (02:12:14 CEST)
Numerous reservoirs that play a significant role in worldwide petroleum production and reserves contain fractures. Typically, the fractures must form a connected network for a reservoir to be classified as naturally fractured. Characterizing the reservoir with a focus on its fracture network is crucial for modeling and predicting production performance. To simplify the solution, dual continuum modeling techniques are commonly employed. However, to use continuum-scale approaches, properties such as average aperture, permeability, and matrix fracture interaction parameters must be assigned, making it necessary to improve fracture depiction and modeling methods. This study investigates a fractured reservoir with a low matrix permeability and a well-connected fracture network. The focus is on the impact of the hyrachical fracture network on the production performance of gas-based enhanced oil recovery methods. The Discrete Fracture Model (DFN) was utilized to create comprehensive two-dimensional models for three processes: Gas Injection (GI), Water Alternating Gas (WAG), and Foam Assisted Water Alternating Gas (FAWAG). Moreover, dimensionless numbers were employed to establish connections between properties across the entire fracture hierarchy, spanning from minor to major fractures and encompassing the fracture intensity. The results indicate that the FAWAG is more sensitive to fracture types and networks than the WAG and GI processes. Hence, the sensitivity of the individual EOR method to the fracture network requires a respective depth of description of the fracture network. However, other factors, such as reservoir fluids properties and fracture properties, might influence the recovery when the minor fracture networks are excluded. This study has determined that, among the enhanced oil recovery (EOR) techniques examined, the significance of the hyrachical depth of fracture networks diminishes as the ratio of major (primary fracture) aperture to the aperture of medium and minor fractures increases. Additionally, the impact of the assisted-gravity drainage method was greater with increased reservoir height; however, as the intensity ratio increased, the relative importance of medium and minor fracture networks decreased.
ARTICLE | doi:10.20944/preprints201808.0021.v1
Subject: Engineering, Industrial And Manufacturing Engineering Keywords: Methane emission; Spontaneous combustion of coal; Sealing the air leakage; Mining fractures; Inorganic solidified foam
Online: 1 August 2018 (12:17:02 CEST)
Abstract: Unusual methane emission and spontaneous combustion of coal induced by the air leakage are both hazards during mining. The most common practice has been to improve mine safety is sealing the mining fractures. In this paper, the methane and geology, coal spontaneous combustion characteristics and the coexistence of methane emission and spontaneous combustion of coal were analyzed. The preparation system of inorganic solidified foam (ISF) in field applications is studied and the working principle of generating device consists of foam generator and mixer was expounded. The technical plan of site construction is that the foam fluids was injected to respectively seal the mining fractures behind hydraulic supports, the cavities of air return corner, and the fractures nearby the coal pillar. After the foam fluids injection, the two stress values in the coal pillar eventually maintained above 15.5Mpa and 13Mpa, respectively. It indicated that the ISF can enhance the bearing stress ability of the coal pillar by transforming the stress state from two dimensional to three dimensional. The methane concentration in the air return corner and air return roadway declined significantly to 0.63% and 0.25%. The differential pressure inside and outside of the 4301(1) goaf fluctuated between -100pa to 150pa and the concentration of CO and O2 declined to 9ppm and 6%. The CO concentration in the air return corner finally reached a stable level of 6ppm. What that all means, the foam fluids can seal the air leakage and inhibit spontaneous combustion of coal effectively.
ARTICLE | doi:10.20944/preprints202308.0883.v1
Subject: Physical Sciences, Optics And Photonics Keywords: interaction of KrF laser with foams; foam-produced plasma expansion; propagation of laser radiation through foams
Online: 11 August 2023 (07:46:55 CEST)
The hydrodynamics of plasma formed in the interaction of 100-ns UV KrF laser pulses with foam targets with volume densities from 5 to 500 mg/cm3 was studied. Initial and dynamic transmittance at 248-nm wavelength have been measured. At intensities about 1012 W/cm2, the propagation rates of radiation through foam targets reached 80 km/s, while plasma stream velocities from both front and rear sides of targets were approximately the same ~ 75 km/s, which confirms a volumetric absorption of radiation within the target thickness and the explosive nature of the plasma formation and expansion.
COMMUNICATION | doi:10.20944/preprints201901.0072.v1
Subject: Engineering, Energy And Fuel Technology Keywords: Electroconductive additive; Sulfur cathode; Aluminum-foam current collector; Areal capacity; C-rate capability; Lithium-ion battery
Online: 8 January 2019 (15:19:26 CET)
Various types of electroconductive additives were evaluated for high C-rate capability in an attempt to extend practical application of high-areal-capacity lithium–sulfur batteries that employ an aluminum-foam current collector. Carbon nanofibers (CNFs) were found to be the most effective additive, with the ability to attain a high-sulfur-loading of 40 mg cm−2. A CNF-containing cell exhibited gravimetric capacities of 1094 and 758 mAh gsulfur−1 (46.8 and 32.4 mAh cm−2) at 0.05 and 0.1 C-rate, respectively, in an ether-based electrolyte. Because a CNF-containing slurry exhibits low viscosity even at a high solid ratio, it could be filled into the aluminum foam. Additionally, a lithium–sulfur battery with high-sulfur-loading had an energy density of ~120 Wh kg−1, a value that was calculated from the weight of the components of the cathode, anode, current collectors, electrolyte, and separator. Assuming that the amount of electrolyte decreases and that the energy density of cells accumulate, a theoretical energy density of 522 Wh kg−1 was estimated. Moreover, it was found that even if a high-areal-capacity was achieved, the discharge capacity converged at a high C-rate, unless there was an improvement in ion diffusion in the bulk electrolyte. This is considered a limitation of sulfur cathodes with high-sulfur-loading.
ARTICLE | doi:10.20944/preprints202306.0867.v1
Subject: Medicine And Pharmacology, Urology And Nephrology Keywords: Sex differences; Chronic Kidney Disease; Atherosclerosis; Foam Cells; Parietal Epithelial Cells (PECs); Angiotensin-Converting Enzyme Inhibitors (ACEi)
Online: 13 June 2023 (03:22:47 CEST)
Background: This study analyzes sex-based differences in renal structure and response to the Angiotensin-Converting Enzyme (ACE) inhibitor enalapril in a mouse model of atherosclerosis. Methods: ApoE-/- mice (8 weeks old) received enalapril (5 mg/kg/day, subcutaneous) or PBS as a control for an additional 14 weeks. Each group consisted of six males and six females. Results: Females exhibited elevated LDL-cholesterol levels, while males presented higher creatinine levels and proteinuria. Enalapril effectively reduced blood pressure in both groups, but proteinuria decreased significantly only in females. Plaque size analysis and assessment of kidney inflammation revealed no significant sex-based differences. However, males displayed more severe glomerular injury, with increased mesangial expansion, mesangiolysis, glomerular foam cells and activated parietal epithelial cells (PECs). Enalapril mitigated mesangial expansion, glomerular inflammation (particularly in females), and the hypertrophy of PECs in males. Conclusion: This study demonstrates sex-based differences in the response to enalapril in a mouse model of atherosclerosis. Males exhibited more severe glomerular injury, while enalapril provided renal protection, particularly in females. These findings suggest potential sex-specific considerations for ACE inhibitor therapy in chronic kidney disease and atherosclerosis cardiovascular disease. Further research is needed to elucidate the underlying mechanism behind these observations.
ARTICLE | doi:10.20944/preprints202301.0583.v2
Subject: Medicine And Pharmacology, Pathology And Pathobiology Keywords: factor XIII; foam cells; macrophages; vascular smooth muscle cells; oxidized LDL; enzyme-modified LDL; transglutaminase; atherosclerotic plaque; cross-linking
Online: 2 February 2023 (11:52:20 CET)
The potentially active A subunit of coagulation factor XIII (FXIII-A) is an intracellular transglutaminase expressed in various cell types including platelets and monocytes/macrophages. It is involved in stabilizing protein structures by cross-linking through Nε-(?-L-glutamyl)-L-lysyl iso-peptide bonds. Macrophages are major cellular constituents of the atherosclerotic plaque and are important in determining its structural/functional features. Two of their important functions are the accumulation of oxidized LDL in the lipid core, and by cross-linking structural proteins they may stabilize the plaque and protect the thrombi of atherogenic origin against fibrinolytic degradation. It is important to know whether these functions operate in parallel utilizing the same cellular compartments. First, we showed that monocyte-derived human macrophages significantly increase their FXIII-A content when up-taking oxidized LDL. This phenomenon is very likely independent of the process of transformation into foam cells, as the transformation of vascular smooth muscle cells into foam cells fails to result in the expression of FXIII-A. FXIII containing macrophage-like cells are abundant in the plaque and FXIII-A is also present in the extracellular core. Several cells co-stained for FXIII-A and for Oil Red O suggest that expression of FXIII-A and lipid up-take are common features of macrophages present in the atherosclerotic plaque.