ARTICLE | doi:10.20944/preprints202304.0664.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: ammonium/nitrate ratio; Arnebia euchroma; shikonin; hairy root; ammonium toxicity
Online: 21 April 2023 (03:30:29 CEST)
Nitrogen (N) strongly affects plant growth and metabolism. For shikonin biosynthesis, although the ammonium toxicity phenomenon has been reported, the effects of nitrogen on the shikonin synthesis remains obscure. In this study, we carried out four different concentrations of NH4+ treatments on Arnebia euchroma hairy roots (AEHR) to clarify the influence of NH4+ on the growth and shikonin accumulation in A. euchroma and the possible mechanism. The results showed that compared with the 0% NH4+ treatment (only nitrate as nitrogen source), 10% NH4+ treatment increased the fresh weight and the dry weight of AEHR, and promoted the synthesis of shikonins; 20% NH4+ treatment started to show the inhibition effects on growth and shikonin accumulation of AEHR and 30% NH4+ treatment exhibited the strongest inhibition effects. With increased percentage of NH4+, AEHRs became shorter and thicker with more branches. To further elucidate the mechanism, we analyzed the time-course of nitrogen assimilation, gene expression level of key enzymes involved in the shikonin biosynthesis pathway, and contents of various endogenous hormones under NH4+ toxicity condition. Results indicated that auxin and cytokinin might regulate the growth and architecture of AEHR under NH4+ toxicity, and jasmonate level was reduced along with the inhibition of shikonin biosynthesis. This first comprehensive investigation into the effects of ammonium/nitrate ratio on shikonin biosynthesis not only provided valuable data for optimizing the in vitro culture and shikonin production in A. euchroma, but also suggested potential fertilizer strategies for its cultivation.
ARTICLE | doi:10.20944/preprints201910.0092.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: galdieria; pH; ammonium; nitrate
Online: 8 October 2019 (11:32:24 CEST)
Galdieria maxima is a polyextremophilic alga capable of diverse metabolic processes. Ammonia is widely used in culture media typical of laboratory growth. Recent reports that this species can grow on wastes promote the concept that G. maxima might have biotechnological utility. Accordingly, there is a need to know the range of pH levels that can support G. maxima growth in a given nitrogen source. Here, we examined the combined effect of pH and nitrate/ammonium source on the growth and long-term response of the photochemical process to a pH gradient in different G. maxima strains. All were able to use differing nitrogen sources, despite both the growth rate and photochemical activity were significantly affected by the combination with the pH. All strains acidified the NH4+-medium (pH<3); only G. maxima IPPAS P507 showed reduced capacity in lowering the pH from 6.5. pH was a limiting factor in nitrate uptake at pH≥6.5; noteworthy, at pH 5 on nitrate G. maxima ACUF551 showed a good growth performance, despite the alkalization of the medium.
ARTICLE | doi:10.20944/preprints202012.0458.v2
Subject: Chemistry And Materials Science, Analytical Chemistry Keywords: ammonium; adsorption; sewage sludge; kinetic; isotherm
Online: 24 December 2020 (13:50:11 CET)
Sewage sludge was utilized into biochar using the slow pyrolysis method. The biochar was then being used for ammonium removal. The sewage sludge biochar was produced at temperature of 550°C, 600°C, 650°C, 700°C and 750°C. A few characterization tests were carried out to study about the physical and chemical properties of the biochar. For instance, moisture and ash content analysis, FTIR spectroscopy, pH Zero Point Charge, biochar yield and SEM. As the pyrolysis temperature increased, the moisture content of SSB decreased while the ash content increased. The FTIR spectra of sewage sludge biochar showed that there were various organic functional groups on the surface of the biochar which were responsible for ammonium adsorption. Furthermore, through pH Zero Point Charge analysis, pH 7.0 was the most optimum pH for the adsorption test of ammonium. The optimum adsorbent dosage was 0.01g while optimum contact time was 150 minutes. Furthermore, 1.2ppm was the most optimum concentration for adsorption process. Based on the result of the characterization tests, SSB700 was the most effective biochar for ammonium adsorption. Based on the result of kinetic and isotherm analysis, the adsorption of ammonium ions usign sewage sludge biochar was a monolayer chemisorption process.
ARTICLE | doi:10.20944/preprints201710.0126.v1
Subject: Chemistry And Materials Science, Organic Chemistry Keywords: (2-fluoro-phenyl)ethanone; phenyl trimethyl ammonium tribromide; 3-bromopyridine-2-amine; zinc dust; ammonium chloride
Online: 18 October 2017 (04:34:12 CEST)
We report here the synthesis and characterization of new N-(3-(8-bromoimidazo[1, 2-a]pyridin-2-yl)-4-fluorophenyl)benzamide derivatives. This collection was obtained from 3-(8-bromoimidazo [1,2-a]pyridin-2-yl)-4-fluoroaniline(5). The family of new compounds was characterized by 1H-NMR, 13C-NMR, FT-IR and LC-MS analysis.
ARTICLE | doi:10.20944/preprints202311.0869.v1
Subject: Environmental And Earth Sciences, Soil Science Keywords: Zea Mays; Urea; Ammonium sulfate; Phenological stage
Online: 14 November 2023 (10:37:34 CET)
The aims of study was to evaluate the effects of rates, sources and timing of nitrogen application under cover of transgenic corn yield cultivated in Amazon Biome. The experiments were conducted in Parauapebas city, State of Pará, Brazil, in two years (2016/2017 and 2017/2018). The experimental design was randomized blocks, in a 5x2x2 factorial scheme, consisting of five rates of N (0; 45; 90; 135; and 180 kg ha-1), two nitrogen sources (urea and ammonium sulfate) and two application times of N (phenological stages V4 and V8), with four replications. The factor N rates promoted adjustment of linear equation (leaf area index, mass of thousand grains, and yield) and quadratic equation (dry mass of leaf index). Nitrogen fertilization promoted significant increases in mass of thousand grains and yield, obtaining the best results with 180 kg ha-1 of N applied at V4 phenological stage. Based on results obtained in two years of corn cultivated under conditions of Amazon Biome, the application of N at V4 phenological stage at rates of 121 to 131.39 kg ha-1 of N showed the best results for vegetative growth, while 180 kg ha-1 of N, regardless of source used, urea or ammonium sulfate, promoted greater grain weight and greater yield.
ARTICLE | doi:10.20944/preprints201803.0138.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: zinc oxide; nanowires; hydrothermal; photoluminescence; ammonium hydroxide
Online: 16 March 2018 (15:35:41 CET)
We report the influence of ammonium hydroxide (NH4OH), as growth additive, on zinc oxide nanomaterial through the optical response obtained by photoluminescence (PL). A low-temperature hydrothermal process is employed for the growth of ZnO nanowires (NWs) on seedless Au surface. A more than two order of magnitude change in ZnO NW density is demonstrated via careful addition of NH4OH in the growth solution. Further, we show by systematic experimental study and PL characterization data that the addition of NH4OH can degrade the optical response of ZnO NWs produced. The increase of growth solution basicity with the addition of NH4OH may slowly degrade the optical response of NWs by slowly etching its surfaces, increasing the point defects in ZnO NWs. The present study demonstrates the importance of growth nutrients to obtain quality controlled density tunable ZnO NWs on seedless conducting substrates.
ARTICLE | doi:10.20944/preprints201809.0190.v1
Subject: Environmental And Earth Sciences, Geochemistry And Petrology Keywords: zeolite; ion-exchange; adsorption; ammonium; Si/Al; temperature
Online: 11 September 2018 (08:50:29 CEST)
We investigate the ammonium removal abilities of natural and synthetic zeolites, which have distinct Si/Al ratios and various surface areas, to study how adsorption and ion-exchange processes in zeolites perform under different ammonium concentrations and different temperatures. Five zeolites including natural mordenite, chabazite, erionite, clinoptilolite and synthetic merlinoite were immersed in 20 mg/kg, 50 mg/kg and 100 mg/kg ammonium solutions. The results demonstrate that zeolites under high ammonium concentrations (100 mg/kg) possess higher physical adsorption capacity (0.398–0.468 meq/g), whereas those under lower ammonium concentrations (20 mg/kg) possess greater ion-exchange property (64–99%). The ion-exchange ability of zeolites are extremely dependent on the cation content of the zeolites, and the cation content is affected by the Si/Al ratio. The surface area of zeolites also has a partial influence on its physical adsorption ability. When the surface area is less than 100 m2/g, the adsorption ability of zeolite increases obviously with surface area; however, adsorption ability is saturated as the surface area becomes larger than this critical value of 100 m2/g. When we carried out the zeolites in 50 mg/kg ammonium concentration at different temperatures (5~50 ℃), we found that zeolites exhibit the highest ammonium removal ability at 30°C and the potassium release was enhanced at 30~40 ℃.
ARTICLE | doi:10.20944/preprints202009.0708.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: Cellulose cationisation; Chromium(VI); acid mine drainage; hemp cellulose; glycidyltrimethylammonium chloride; 3-chloro-2-hydroxypropyl trimethyl ammonium chloride; quaternary ammonium salts
Online: 29 September 2020 (12:44:08 CEST)
Cationised hemp cellulose was prepared by etherification with two quaternary ammonium salts: 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTAC) and glycidyltrimethylammonium chloride (GTMAC) and examined for (i) the efficiency of Cr(VI) removal under acid mine-drainage (AMD) conditions, and (ii) antibacterial activity. Adsorbents were characterised by electron microscopy, Fourier transform infrared (FTIR), CP-MAS 13C nuclear magnetic resonance (NMR) spectroscopy, elemental composition and surface charge. FTIR and solid state 13C NMR confirmed the introduction of quaternary ammonium moieties on cellulose. 13C NMR also showed that cationisation decreased the degree of crystallisation and lateral dimensions of cellulose fibrils. Nevertheless, 47 % - 72% of Cr(VI) ions were removed from solutions at pH 4, by 0.1 g of CHPTAC and GTMAC-cationised cellulose, respectively. Adsorption kinetics followed the pseudo-second order model and isotherms were best described by the Freundlich and Dubinin-Radushkevich models. When GTMAC-modified cellulose was applied to AMD contaminated water (pH 2.7), however, Cr(VI) uptake removal decreased to 22% likely due to competition from Al and Fe ions. Nevertheless, cationised materials displayed considerable antibacterial effects, reducing the viability of Escherichia coli by up to 45 % after just 3 hours of exposure. Together, these results suggest that cationised cellulose can be applied in the treatment of Cr(VI)-contaminated mine water particularly if pre-treatments to reduce Fe and Al concentrations are applied.
ARTICLE | doi:10.20944/preprints202309.0397.v2
Subject: Chemistry And Materials Science, Chemical Engineering Keywords: hydrothermal carbonization; cellulose; ammonium sulfate; thiourea; doping; supercapacitor carbon
Online: 7 September 2023 (11:45:43 CEST)
Hydrothermal carbonization of cellulose was examined at 240 ℃ for 1 h. Ammonium sulfate and thiourea were selected as the doping sources of inorganic nitrogen and organic nitrogen for the preparation of supercapacitor carbon. The effect of boric acid on the properties of the resulting hydrochar after KOH activation was examined. The results showed that the proportion of functional groups and the specific surface area of the activated hydrochar would be reduced after the addition of boric acid, and the pore-forming process of the micropores would be inhibited. The hydrochar obtained from the reaction of cellulose and organic nitrogen compounds had better pore size distribution and electrochemical properties after activation. The largest specific surface area (952.27 m2 g-1) was obtained when only thiourea was used as the only doping source. In the three-electrode system, the specific capacitance resulting activated hydrochar reached 236.25 F g-1 at a current density of 1 A g-1. After 20,000 cycles of charging and discharging at a current density of 10 A g-1, the capacitance retention rate reached 99.96%. Therefore, this study proves that the supercapacitor carbon with good electrochemical properties could be obtained by the direct reaction of cellulose with organic nitrogen compounds.
ARTICLE | doi:10.20944/preprints202301.0199.v1
Subject: Biology And Life Sciences, Forestry Keywords: Prunus cerasus; ammonium nitrate; chlorophyll; TCSA; mineral content; carotenoids
Online: 11 January 2023 (10:40:29 CET)
Nitrogen fertilization ensures the proper growth of trees. The aim of the study was to evaluate the impact of differentiated nitrogen fertilization on selected parameters. It was assumed that such analysis is an indirect picture of the needs of cherries grown in herbicide fallow. The content of minerals in two layers of the soil, in leaves, and its influence of tree growth, and the content of chlorophyll in leaves were assessed. The experiments were carried out in three different cherry orchards. Three levels of fertilization were applied in each orchard: 0 kg, 60 kg and with 120 kg N ha- 1. As expected the fertilization resulted in an increase in the content of nitrate and ammonium forms of nitrogen in the soil, however, their content was also dependent on precipitation and temperature. Additionally a high nitrogen fertilization increased the content of phosphorus and potassium and decreased the magnesium in the topsoil layer. High nitrogen fertilization caused the decrease of content of phosphorus and potassium in the leaves. The level of calcium and magnesium in leaves increased with fertilization of 60 kg N ha–1 but decreased with the dose to 120 kg N ha–1. The use of nitrogen fertilization increased the vegetative growth of trees measured by leaf area and trunk cross-sectional area. However, the chlorophyll content was not dependent on the amount of nitrogen fertilization.
ARTICLE | doi:10.20944/preprints202107.0197.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: fishery waste; epoxy; fish scale; ammonium polyphosphate; flame retardant
Online: 8 July 2021 (11:04:10 CEST)
In this study, a composite flame retardant was created by combining fish scale (FS), fishery waste, and ammonium polyphosphate (APP), a commercially available flame retardant. The composite flame retardant was added to epoxy resin (EP) to form an EP/APP/FS composite that prevents burns and is environmentally friendly. The use of FS conforms to the concept of circular economy and lowers costs by reducing the consumption of APP. Thermogravimetric analysis (TGA), integral procedural decomposition temperature (IPDT), pyrolysis kinetics, limiting oxygen index (LOI), the Underwriters Laboratories 94 (UL94) flammability test, scanning election microscopy, Raman spectroscopy, and energy-dispersive X-ray spectroscopy were used to determine the thermal properties, flame retardant properties, flame retardant mechanism, char morphology, and composition of the composites. The TGA results indicated that the addition of 40% flame retardant raised the char residue from 16.45 wt% (pure EP) to 36.07 wt%, IPDT from 685.6 °C (pure EP) to 1143.1°C, LOI from 21% (pure EP) to 30%, and UL94 classification from fail (pure EP) to V-0. These results suggest an increase in char residue, which indicates better protection of the polymer matrix material. The improvements in IPDT, LOI, and UL94 classification, which indicate greater thermal stability, lower flammability (from flammable to fireproof), and higher flammability rating (from fail to V-0), respectively, suggest that the composite material has favorable thermal properties and is less inflammable.
ARTICLE | doi:10.20944/preprints202107.0006.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: nitrogen cycle; ammonium; nitrate; nitrite; stratification; boreal; meromictic lake
Online: 1 July 2021 (09:33:16 CEST)
In order to better understand the biogeochemical cycle of nitrogen in meromictic lakes, which can serve as a model for past aquatic environments, we measured dissolved concentrations of nitrate, nitrite, ammonium and organic nitrogen in deep (39 m maximal depth) subarctic Lake Svetloe (NW Russia). The lake is a rare type of freshwater meromictic water boy with high concentrations of methane, ferrous iron, manganese and low concentrations of sulfates and sulfides in the monimolimnion. In the oligotrophic mixolimnion, the concentration of mineral forms of nitrogen decreased in summer compared to winter, likely due to phytoplankton bloom. The decomposition of the bulk of organic matter occurs under microaerophilic/anaerobic conditions of the chemocline and accompanied by the accumulation of nitrogen in the form of N-NH4 in the monimonimlion. We revealed a strong relationship between methane and nitrogen cycles in the chemocline and monimolimnion horizons. The nitrate concentrations in Lake Svetloe varied in the range from 9 to 13 μM throughout the water column. This fact is rare for meromictic lakes, where nitrate concentrations up to 13 µM are found in the monimolimnion zone down to the bottom layers. We hypothesize, in accord with available data for other stratified lakes, that under conditions of high concentrations of manganese and ammonium at the boundary of redox conditions and below, anaerobic nitrification with the formation of nitrates occurs. Overall, most of organic matter in Lake Svetloe undergoes biodegradation essentially under microaerophilic/anaerobic conditions of the chemocline and the monimolimnion. Consequently, the manifestation of the biogeochemical nitrogen cycle is expressed in these horizons in the most vivid and complex relationship with other cycles of elements.
ARTICLE | doi:10.20944/preprints201910.0323.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: catalase activity; hydrogen peroxide; hydroquinone; anilinium sulfate; ammonium molybdate
Online: 29 October 2019 (04:04:50 CET)
Background: Catalase is a vital antioxidant enzyme that dismutates H2O2 into water and molecular oxygen. Many protocols have been developed to measure catalase enzyme activity. Spectrophotometric methods are the most common assays that used to assess catalase enzyme activity. Methods: Because the rate-limiting step during catalase enzyme activity depends upon the dissociation of hydrogen peroxide, the developed assay measures the reaction between a hydroquinone/anilinium sulfate/ammonium molybdate reagent and Unreacted Hydrogen Peroxide, which results in the production of a purple, disubstituted quinone compound with a maximum absorbance value at 550 nm. Results: To clarify the precision of the developed method, the coefficients of variation were determined to be 2.6% and 4.7% for within run measurements and between run measurements, respectively. This method returned results that correlated well (r = 0.9982) with the results returned using the peroxovanadate method to assess catalase enzyme activity. Additionally, we examined the use of the newly developed hydroquinone assay to measure catalase enzyme activity in liver and bacterial homogenate samples. Conclusion: These results demonstrated that this assay can be used for scientific research and routine health applications because it is inexpensive, simple, accurate, and rapid. This method is suitable for use in clinical pathology laboratories because it is simple and produces precise and reproducible results.
ARTICLE | doi:10.20944/preprints201610.0059.v1
Subject: Engineering, Metallurgy And Metallurgical Engineering Keywords: ammonium–arsenic jarosite; characterization; chemical decomposition and thermal decomposition
Online: 14 October 2016 (11:27:36 CEST)
Arsenic, an element of environmental impact, can be incorporated into jarosite–type compounds and remain stabilised within the structure under a wide range of environmental conditions. In this study, a sample of ammonium–arsenic jarosite was synthesised by precipitation in sulphate medium at controlled pH of 1.2–1.8. The behaviour of arsenic during the thermal and chemical decomposition of jarosite was analysed; the degradation in alkaline medium of jarosite was also studied. According to the results, the synthesised jarosite is composed of joined rhombohedral crystals, forming tightly spherical shaped particles, 37–54 μm size. The ammonium jarosite produced possessed a high arsenic concentration; its calculated stoichiometry being (NH4)Fe2.45[(SO4)1.80(AsO4)0.20][(OH)4.15(H20)1.85]. It was found that arsenic is stabilised in the jarosite structure; upon heating, it remains in residual solids above 700°C, whilst in alkaline medium an incongruent dissolution takes place, with the arsenic retained in the solid phase along with iron. These solids, when exposed to high temperatures (1200°C), transform into a type of iron oxide known as hematite, so with arsenic it is retained an iron compound forming a stable compound which withstands high temperatures.
ARTICLE | doi:10.20944/preprints202310.1510.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Drosophila; signaling pathway; domesticated retroviral gag gene; immunity; ammonium persulphate
Online: 24 October 2023 (08:35:20 CEST)
Background: The molecular domestication of the gag gene of retrotransposons and retroviruses gave rise to the Gagr gene in the genome of Drosophila. The Gagr protein has a conservative structure in all Drosophila species, suggesting an essential function. As we previously shown, the Gagr gene may play a part in immune response and processes linked to stress reactions. Methods: Tub-GAL4>UAS-Gagr flies, which had the Gagr gene knockdown in all tissues, were compared with the control hybrid Tub-GAL4>w1118. Gagr gene function was verified by RNA-sequencing followed by RT-PCR and physiological tests. Results: In contrast to the control strain, we observed that flies with the Gagr gene knockdown had a shorter lifespan, but the mutant strain was more resistant to heat stress. Also, the Gagr knockdown strain had higher level of transcription of the immune response genes, according to a transcriptome analysis. It has been shown that the ammonium persulfate used to induce stress causes the Toll, Jal-STAT, and Jnk/MAPK signaling pathways to become activated, which results in a systemic response in numerus tissues in the control strain. Conversely, the Gagr gene mutant strain exhibits low expression of the stress response. Enrichment of the molecular function of genes overexpressed under ammonium persulfate stress in the control strain, but not in the Gagr knockdown mutant, revealed a category with 19 transcription factors involved in the control of organism development, morphogenesis and the functioning of the central nervous system. Their expression pattern and the Gagr gene's expression pattern match. The data obtained demonstrates the importance Gagr is to maintaining both the body's immune system and homeostasis.
COMMUNICATION | doi:10.20944/preprints202309.0128.v1
Subject: Engineering, Mining And Mineral Processing Keywords: Hematite; Quartz; Cetyl trimethyl ammonium chloride; Selective adsorption; Flotation separation
Online: 4 September 2023 (07:21:40 CEST)
In this research, a novel collector cetyl trimethyl ammonium chloride (CTAC) was used to separate hematite from quartz via reverse flotation for the first time. Micro-flotation tests showed that CTAC had a strong ability to selectively collect quartz and a separation of hematite from quartz could be accomplished with a concentration of 0.00263 mmol/L CTAC. Zeta-potential measurements indicated that the positive CTAC+ species could selectively increase the surface potential of quartz, but it had rather a weak effect on the hematite surface. X-ray photoelectron spectroscopy (XPS) detection indicated that CTAC had a stronger binding affinity to oxygen sites on the surface of quartz than that of hematite, resulting in a large amount of CTAC predominantly adsorbed on quartz rather than hematite.
ARTICLE | doi:10.20944/preprints202211.0305.v1
Subject: Biology And Life Sciences, Horticulture Keywords: ammonium transport; flowering Chinese cabbage; NH4+; NO3-; ion influx; overexpression
Online: 16 November 2022 (10:20:07 CET)
Nitrogen (N) is a major limiting factor for plant growth and vegetable production. Understanding the regulatory mechanisms of N uptake, transport, and assimilation is key to improving nitrogen use efficiency in plants. Ammonium transporters (AMTs) play an important role in plant N metabolism. In this study, we isolated an important AMT1 subfamily member (BcAMT1;5) with a highly conserved signatural AMT1 subfamily motif from flowering Chinese cabbage. Based on functional complementation in yeast mutant 31019b and overexpression of BcAMT1;5 in Arabidopsis, BcAMT1;5 is a functional ammonium transporter. Tissue expression analysis showed that BcAMT1;5 was mainly expressed in roots and showed multiple N regime transcript patterns to respond to varying nutritional conditions. This was up-regulated by N-deficiency and down-regulated by supplying NH4+. The glucuronidase (GUS) activities of BcAMT1;5pro::GUS showed a similar change in response to different N conditions. Overexpression of BcAMT1;5 accelerated the growth of transgenic seedlings, increased NH4+ net influxes, and enhanced the content and accumulation of NH4+ and NO3- at low N concentrations. Additionally, it increased the transcript levels of N assimilation-related genes in shoots. These results indicate that the transcriptional regulation of BcAMT1;5 in flowering Chinese cabbage may participate in N uptake and assimilation under various N conditions.
ARTICLE | doi:10.20944/preprints202205.0055.v1
Subject: Chemistry And Materials Science, Physical Chemistry Keywords: ion exchange membrane; diffusion permeability; weak electrolyte; ammonium chloride; simulation
Online: 5 May 2022 (16:49:08 CEST)
It is known that ammonium has a higher permeability through anion-exchange and bipolar membranes compared to K+ cation that has the same mobility in water. However, the mechanism of this high permeability is not clear enough. We develop a mathematical model based of the Nernst-Planck and Poisson equations for diffusion of ammonium chloride through an anion-exchange membrane; proton exchange reactions between ammonium, water and ammonia are taken into account. It is assumed that ammonium, chloride and OH− ions can only pass through membrane hydrophilic pores, while ammonia can also dissolve in membrane matrix fragments not containing water and diffuse through these fragments. It is found that due to the Donnan exclusion of H+ ions as coions, the pH in the membrane internal solution increases when approaching the membrane side facing distilled water. Consequently, there is a change in the principal nitrogen-atom carrier in the membrane: in the part close to the side facing the feed NH4Cl solution (pH<8.8), it is the NH4+ cation, and in the part close to distilled water, NH3 molecules. The concentration of NH4+ reaches almost zero at a point close to the middle of the membrane cross-section, which approximately halves the effective thickness of the diffusion layer for the transport of this ion. When NH3 takes over the nitrogen transport, it only needs to pass through the other half of the membrane. Leaving the membrane, it captures an H+ ion from water, and the released OH− goes towards the membrane side facing the feed solution to meet the NH4+ ions. The comparison of the simulation with experiment shows a satisfactory agreement.
ARTICLE | doi:10.20944/preprints202010.0581.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: ionic exchange; self-assembly; modified ammonium polyphosphate; polypropylene; combustion behavior
Online: 28 October 2020 (10:06:57 CET)
Modified ammonium polyphosphate (MAPP) as a novel mono-component intumescent flame retardant (IFR) was prepared via the ionic exchange between ammonium polyphosphate (APP) and piperazine sulfonate, which is synthesized by self-assembly using 1-(2-Amioethyl) piperazine (AEP) and p-amino benzene sulfonic acid (ASC) as raw materials. This all-in-one IFR integrating three functional elements (carbon, acid, and gas source) showed more efficient flame retardancy and excellent smoke suppression as well as better mechanical properties than the conventional APP. The incorporation of 22.5 wt.% MAPP into polypropylene (PP) eliminated the melt dripping phenomenon and passed the UL-94 V-0 rating. The results of the cone calorimetry test (CCT) revealed that the release of heat, smoke, and CO is significantly decreased, demonstrating that this novel IFR endows PP with excellent fire safety more effectively. For PP/MAPP composites, a possible IFR mechanism was proposed based on the analysis of the pyrolysis gas and char residues.
ARTICLE | doi:10.20944/preprints202004.0044.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: halophyte; salt-tolerance; N-nutrition; Portulaca oleracea; oxalic acid; ammonium nutrition
Online: 6 April 2020 (09:21:14 CEST)
Halophytic plants are, by definition, well adapted to saline soils. However, even halophytes can face nutritional imbalance and accumulation of high levels of compounds such as oxalic acid (OA), and nitrate (NO3¯). These compounds compromise the potential nutritional health benefits associated with salt tolerant plants such as Portulaca oleracea. Thus, preventing the accumulation of non-nutritional compounds will allow plants to be grown in saline conditions as crops. To this end, two ecotypes (ET and RN) of Portulaca oleracea plants were grown under growth room conditions with two levels of salinity (0, 50 mM NaCl) and three ratios of nitrate: ammonium (0:100%; 33:66%; 25:75% NO3¯:NH4+). The results showed that both ecotypes exposed to elevated NO3¯, showed severe leaf chlorosis, high levels of OA, citric acid, and malic acid, while plants of ecotype ET exposed to elevated NH4+ concentrations (33% and 75%) and 50 mM NaCl displayed a marked reduction in OA content, increased total chlorophyll and carotenoid contents, crude protein content, total fatty acid (TFA) and α-Linolenic acid (ALA) thus enhancing leaf quality. This opens the potential to grow high biomass, low OA P. oleracae crops. Lastly, our experiments suggest that ecotype ET copes with saline conditions and elevated NH4+ through shifts in leaf metabolites.
ARTICLE | doi:10.20944/preprints201808.0479.v1
Subject: Biology And Life Sciences, Ecology, Evolution, Behavior And Systematics Keywords: COS production; COS uptake; Carbonic anhydrase; nitrate; ammonium; sulfur; microbial community
Online: 29 August 2018 (01:07:13 CEST)
Soils are an important COS sink. However they can also act as sources of COS to the atmosphere. Here we demonstrate that variability in the soil COS sink and source strength is strongly linked to available soil inorganic nitrogen (N) content across a diverse range of biomes in Europe. We revealed in controlled laboratory experiments that N fertilisation simultaneously decreases the COS sink strength of soils while increasing the COS production rate. Furthermore, we found strong links between variations in the two gross COS fluxes, microbial biomass and nitrate and ammonium contents, providing new insights into the mechanisms involved. Our findings provide evidence for how soil-atmosphere exchange of COS is likely to vary spatially and temporally, a necessary step for constraining the role of soils and land use in the COS mass budget.
ARTICLE | doi:10.20944/preprints201810.0170.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: antibacterial; biofilm; caries; dental composite; quaternary ammonium monomers; human in situ study
Online: 9 October 2018 (04:43:45 CEST)
Cariogenic oral biofilms cause a considerable amount of recurrent dental caries around composite restorations every year, resulting in unprosperous oral health status and expensive restorative treatment for many patients. Quaternary ammonium monomers that can be copolymerized with the current dental resin systems have been increasingly explored for modulation of dental plaque biofilm growth over dental composite surfaces. Here, we investigated the effect of bis(2-methacryloyloxyethyl) dimethylammonium bromide (QADM), against human overlying mature oral biofilms grown intra-orally in human participants for 7 and 14 days, for the first time. Seventeen volunteers wore palatal devices containing composite specimens containing 10% by mass of QADM or a control composite without QADM. After 7 and 14 days, the adherent biofilms were collected for determination of bacterial counts via colony-forming unit (CFU) counts. The biofilm viability, chronological changes, and percentage coverage were also determined by live/dead staining. QADM composites caused a significant inhibition of S. mutans biofilm formation for up to seven days. No difference in the CFU values were found for the 14-day period. Our findings suggest that (1) QADM composite was successful in inhibiting 1-3 day biofilms in the oral environment in vivo; (2) QADM significantly reduced the portion of S.mutans group in a time course where patients at high risk of caries would develop initial enamel carious lesions; and (3) stronger antibiofilm activity is required for the control of mature long-term cariogenic biofilms. These results provide a perspective on the value of integrating bioactive restorative materials with traditional caries management approaches into clinical practice. Contact-killing strategies via dental materials aiming to prevent or at least reduce high numbers of cariogenic bacteria seem to be a promising approach in patients at high risk of recurrence of dental caries around composites.
REVIEW | doi:10.20944/preprints202309.0447.v1
Subject: Environmental And Earth Sciences, Water Science And Technology Keywords: waste-as-resource; zeolite-precursor; sorption; surface-modified zeolites; ammonium; phosphate; reuse; regeneration
Online: 7 September 2023 (05:03:31 CEST)
The feasibility of using zeolites, synthesized from components found in municipal solid waste fly ash (MSW-FA), as sorbents for the recovery of nutrients (nitrate and phosphate) and heavy metals is critically assessed in this review. The inherent drawbacks of utilising a highly contaminated, variable, and relatively Al- and Si-dilute source such as MSW-FA to synthesize zeolites are discussed, and different methods to extract and decontaminate zeolite precursor materials from MSW-FA are considered. Ways to synthesize tailored zeolites and how their properties as well as the operational conditions impact the adsorption of cations such as ammonium and heavy metals are summarized. The use of surface-modified zeolites to adsorb nitrate and phosphate is also reviewed. And subsequently, approaches to utilise directly or recover for reuse the adsorbed compounds are considered, discussing potential challenges and mitigating measures related to leaching of unwanted compounds from the zeolites. Moreover, the possibility to regenerate the adsorption capacity of the zeolites for multiple adsorption cycles is considered. In the final chapter of the review a more general discussion of the main challenges and existing research gaps is provided, giving directions for recommended studies.
ARTICLE | doi:10.20944/preprints202302.0194.v1
Subject: Biology And Life Sciences, Biology And Biotechnology Keywords: Cyanobacteria,; Bisabolene; Farnesene; Limonene; Pinene; Nitrogen sources; Ammonium; Nitrate; Urea; Genetic engineering; Bioproduction
Online: 13 February 2023 (02:15:21 CET)
We have performed the first comparative analysis of the potential of two physiologically-diverse model cyanobacteria, Synechococcus PCC 7002 (S.7002) and Synechococcus PCC 7942 (S.7942), for the photosynthetic production of four chemically-different high-value terpenes: two monoterpenes limonene and pinene, and two sesquiterpenes bisabolene and farnesene. We showed, for the first time, that S.7002 and S.7942 can produce farnesene and bisabolene, respectively. Both cyanobac-teria produced farnesene (S.7942 better than S.7002) more efficiently than the other tested terpenes (especially pinene the weakest produced terpene). S.7002 produced limonene better than bisabo-lene, whereas S.7942 produced bisabolene better than limonene. These findings suggest that S.7942 is better suited to produce sesquiterpenes than monoterpenes. Also interestingly, higher levels of terpenes were produced by S.7942 and S.7002 expressing a terpene-synthase gene from both a RSF1010-derived replicating plasmid and a neutral chromosomal site, as compared to ei-ther the plasmid alone or the chromosome alone. These results suggest that in both cyanobacteria the production of terpenes is more limited by the activity of terpene synthases than the abondance of terpene precursors. Finally, higher levels of terpenes were produced by S.7002 growing on urea (a frequent pollutant) as compared to nitrate (or ammonium) the standard nitrogen sources for cyanobacteria (more expensive than urea).
ARTICLE | doi:10.20944/preprints202007.0730.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: TSS; fruit quality; firmness; ammonium thiosulphate; skin colour; tree vigour; thinning of flowers
Online: 31 July 2020 (04:54:38 CEST)
The study’s objective was to evaluate the influence of thinning on the quality and regularity of yield of 'Regina' cherries grown on a dwarf Gisela 5 rootstock. The experiments were conducted in the years 2009-2012 in Western Poland. Trees were thinned using a chemical agent, ammonium thiosulphate (ATS) at doses of 20g ATS × L-1, 30g ATS × L-1 and 40g ATS × L-1, and by hand, and the results of chemical and hand thinning were compared with those obtained for unthinned trees. The course of weather conditions in winter and during flowering had a significant impact on yield. Chemical thinning is known to be an effective method to regulate fruiting of pome trees, but it can also be successful if applied to cherry trees, as reflected by the alternate bearing index, which was the lowest after applying ATS at a dose of 40g. ATS treatment improved fruit quality in full crop years. Thinning resulted in, among other things, larger and darker fruit and higher content of total soluble solids and titratable acidity. Treatment with 40g ATS × L-1 significantly stimulated the vegetative growth of trees.
ARTICLE | doi:10.20944/preprints201909.0311.v1
Subject: Chemistry And Materials Science, Applied Chemistry Keywords: polyelectrolyte; quaternary ammonium; phytic acid; multivalent ion effect; ion bridges; specific ion effect
Online: 27 September 2019 (10:37:36 CEST)
Tough and antimicrobial dual-crosslinked poly((trimethylamino)ethyl methacrylate chloride)-phytic acid hydrogel (pTMAEMA-PA) has been synthesized by adding chemical crosslinker and docking physical crosslinker of multivalent phytic acid into a cationic polyelectrolyte network. By increasing the loading concentration of PA, the tough hydrogel exhibits compressive stress of >1 MPa, along with high elasticity and fatigue-resistant properties. The enhanced mechanical properties of pTMAEMA-PA were stem from multivalent ion effect of PA via the formation of ion bridges within polyelectrolytes. In addition, a comparative study for a series of pTMAEMA-counterion complexes was conducted to elaborate the relationship between swelling ratio and mechanical strength. The study also revealed secondary factors, such as ion valency, ion specificity and hydrogen bond formation, holding crucial roles in tuning mechanical properties of the polyelectrolyte hydrogel. Furthermore, in bacteria attachment and disk diffusion tests, pTMAEMA-PA exhibits superior fouling resistance and antibacterial capability. The results reflect the fact that PA enables chelating strongly with divalent metal ions, hence, disrupting the outer membrane of bacteria, as well as dysfunction of organelles, DNA and protein. Overall, the work demonstrated a novel strategy for preparation of tough polyelectrolyte with antibacterial capability via docking PA to open up the potential use of PA in medical application.
ARTICLE | doi:10.20944/preprints202309.0720.v1
Subject: Biology And Life Sciences, Life Sciences Keywords: Piriformospora indica; nitrogen starvation; nitrogen metabolism; nitrate transporter; ammonium transporter; amino acid transporter; endophyte
Online: 12 September 2023 (03:36:42 CEST)
The root-colonizing endophytic fungus Piriformospora indica promotes root and shoot growth of its host plants. We show that growth promotion of Arabidopsis leaves is abolished when the seedlings are grown on media with nitrogen (N) limitation. The fungus neither stimulated the total N content nor did it promote 15NO3- uptake from agar plates to the leaves of the host under N-sufficient or N-limiting conditions. However, when the roots were co-cultivated with 15N-labelled P. indica, more label can be detected in the leaves of N-starved host plants, but not of plants supplied with sufficient N. Amino acid and primary metabolite profiles, as well as expression analyses of N metabolite transporter genes suggest that the fungus alleviates the adaptation of its host to the N limitation condition. P. indica alters the expression of transporter genes which participate in relocation of NO3-, NH4+ and N metabolites from the roots to the leaves under N limitation. We propose that P. indica participates in the plant´s metabolomic adaptation to N limitation by delivering reduced N metabolites to the host, alleviating metabolic N starvation responses, and reprogramming the expression of N-metabolism related genes.
ARTICLE | doi:10.20944/preprints202111.0280.v1
Subject: Medicine And Pharmacology, Pharmacology And Toxicology Keywords: eDNA; antibiotic resistance; biofilms; biocides; disinfectant; alcohols; hydrogen peroxide; quaternary ammonium compounds; PHMG-Cl
Online: 16 November 2021 (09:07:41 CET)
The choice of effective biocides used for routine hospital practice should consider the role of disinfectants in the maintenance and development of local resistome and how they might affect antibiotic resistance gene transfer within the hospital microbial population. Currently, there is little understanding of how different biocides contribute to eDNA release that may contribute to gene transfer and subsequent environmental retention. Here we investigated how different biocides affected the release of eDNA from mature biofilms of two opportunistic model strains Pseudomonas aeruginosa ATCC 27853 (PA) and Staphylococcus aureus ATCC 25923 (SA) and contribute to the hospital resistome in the form of surface and water contaminants and dust particles. The effect of four groups of biocides including alcohols, hydrogen peroxide, quaternary ammonium compounds, and polymeric guanidines were evaluated using PA and SA biofilms. Most biocides, except for PHMG-Cl and 70% ethanol, caused substantial eDNA release and PHMG-Cl was found to block biofilm development when used at concentrations of 0.5% and 0.1%. This might be associated with the formation of DNA-PHMG-Cl complexes as PHMG-Cl is predicted to bind to AT base pairs by molecular docking assays. PHMG-Cl was found to bind high molecular DNA and plasmid DNA and continued to inactivate DNA on surfaces even after four weeks. PHMG-Cl also effectively inactivated biofilm-associated antibiotic resistance gene eDNA released by a pan-drug-resistant Klebsiella strain which demonstrates the potential of PHMG-Cl as a new surface-active agent to combat the spread of antibiotic resistance in hospital settings.
ARTICLE | doi:10.20944/preprints201910.0252.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: ferric ammonium citrate; deferoxamine; 2,2′-bipyridine; iron homeostasis; ISC; mitochondrial clearance; longevity; starvation; Parkinson’s disease
Online: 22 October 2019 (05:01:43 CEST)
Lifespan extension was recently achieved in Caenorhabditis elegans nematodes by mitochondrial stress and mitophagy, triggered via iron depletion. Conversely in man, deficient mitophagy due to Pink1/Parkin mutations triggers iron accumulation in patient brain and limits survival. We now aimed to identify murine fibroblast factors, which adapt their mRNA expression to acute iron manipulation, relate to mitochondrial dysfunction and may influence survival. After iron depletion, expression of the plasma membrane receptor Tfrc with its activator Ireb2, the mitochondrial membrane transporter Abcb10, the heme-release factor Pgrmc1, the heme-degradation enzyme Hmox1, the heme-binding cholesterol metabolizer Cyp46a1, as well as the mitophagy regulators Pink1 and Parkin showed a negative correlation to iron levels. After iron overload, these factors did not change expression. Conversely, a positive correlation of mRNA levels with both conditions of iron availability was observed for the endosomal factors Slc11a2 and Steap2, as well as for the iron-sulfur-cluster (ISC)-containing factors Ppat, Bdh2 and Nthl1. Positive correlation only after iron depletion was observed for the iron export factor Slc40a1, mitochondrial iron transporters Slc25a28, Abcb7 and Abcb8, mitochondrial ISC-containing factors Glrx5, Nfu1, Bola1 and Abce1, cytosolic Aco1 and Tyw5, as well as nuclear Dna2, Elp3, Pold1 and Prim2. The latter are regulators of nucleotide synthesis and DNA quality control, which have known importance for growth and lifespan. The only Pink1-/- triggered transcript modulation was the reduced expression of the ISC-containing ribosomal factor Abce1. These mammalian findings support previous fly data that Pink1 influences co-translational quality control via Abce1, as well as mitophagy. Our findings provide the first systematic survey how iron dosage triggers homeostatic transcriptional regulations and elucidate how iron deprivation results in mitophagy.
ARTICLE | doi:10.20944/preprints202303.0216.v1
Subject: Engineering, Chemical Engineering Keywords: Waste valorization; stabilization; nutrient recovery; closed-loop; modelling; circular economy; ammonium carbonate; organic fertilizer; bioenergy; biogas upgrading
Online: 13 March 2023 (04:42:38 CET)
The use of the commercial simulator Aspen Plus® could bring an amelioration in the accuracy of the predictions of the chemical species composition in the output streams of the anaerobic digestion process, due to availability of a broad library of thermodynamic and phenomena transport properties in this commercial package. In the present investigation, the process simulation model for anaerobic digestion, which was originally developed by Rajendran et al. , has been modified by including a stoichiometric-equilibria reactor to calculate the extent of the ionization of the molecules present in the anaerobic digestate. The refined model offers a more accurate prediction of the composition of the biogas because it delves on the chemical equilibrium of the gaseous stream and the anaerobic digestate. Additionally, the refined model allows to assess the possibility of upgrading the gaseous stream to biomethane degree via manufacturing of ammonium bicarbonate. This processing pathway relies on the stabilization of the anaerobic digestate by means of biomass ash-based treatment. First of all, the titration of the manure digestate with the hydrochloric acid showed that a dose of 3.18 mEq/g would be required to attain the targeted pH of zero-point charge, upon addition of the sewage sludge ash in a ratio to the manure digestate of 0.6 ± 0.2 %. Secondly, the profiles of ammonia, carbon dioxide, and methane found in the biogas agree with both the pH of the treated digestate and the processes described in for the simultaneously upgrading the biogas and the production of ammonium bicarbonate. The refined Aspen Plus® model presented in this article needs to be further developed to ensure the standards are attained in all output streams of stabilized anaerobic digestate, biomethane, and isolated added-value chemical fertilizers.
ARTICLE | doi:10.20944/preprints202307.1576.v1
Subject: Chemistry And Materials Science, Polymers And Plastics Keywords: polymer inclusion membranes; iron(III); nickel(II); cobalt(II); lithium(II); ionic liquids; tetrabutyl ammonium bromide(TBAB); separation processes
Online: 24 July 2023 (10:58:58 CEST)
The selective extraction of metals from aqueous solutions is very important stage in hydrometallurgical processing of metallic waste. Leach solutions are usually a multi-component mixture. The main impurity of aqueous solutions obtained after leaching using inorganic acids is iron. In this work, the membrane separation of iron(III) from nickel(II), cobalt(II) and lithium(II) was studied. The facilitated transport of metal ion using the polymer inclusion membranes (PIMs) with tetrabutylammonium bromide (TBAB) as an ion carrier under various conditions was analyzed in detail. The several factors such as the ion carrier concentration in the membrane as well as the effect of the inorganic acids concentration in the source/receiving phases on the kinetic parameters were investigated. The results show that ionic liquid TBAB is a very selective ion carrier of Fe(III) towards Ni(II), Co(II) and Li(I) .
REVIEW | doi:10.20944/preprints202201.0266.v1
Subject: Chemistry And Materials Science, Theoretical Chemistry Keywords: smectic T; lamellar; tetragonal symmetry; liquid crystals; square lattice; lattice parameter; thermotropic; two-dimensional organization; 2D positional order; quaternary ammonium
Online: 19 January 2022 (08:45:23 CET)
An overview of the chemical compounds forming the rare smectic T phases is cited with references to the historical context. Thermodynamics (transition temperatures, enthalpies) along with the factors (stereochemical constraints, electrostatic interactions, aliphatic chain stacking, intermolecular forces) contributing to the adoption of tetragonal scaffolds are also discussed. Characteristic optical microscopy textures and x-rays diffraction patterns are presented. In parallel, a comparison of the geometrical parameters such as distances between atoms, molecular areas, volumes, and lattice parameters with the closest two-dimensional and three-dimensional organizations, is performed.