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1,729 result(s) for "Ammonium acetate"
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Dependence of cellulose dissolution in quaternary ammonium acetates/DMSO on the molecular structure of the electrolyte: use of solvatochromism, micro-calorimetry, and molecular dynamics simulations
We studied the dissolution of microcrystalline cellulose (MCC) at 60 °C in binary mixtures of dimethyl sulfoxide (DMSO) and the following quaternary ammonium acetates (QAAcOs): benzyl-trimethylammonium, NBzMe3AcO; diallyl-benzyl-methylammonium, NAl2BzMeAcO, tetra(n-butyl)ammonium (NBu4AcO), and tribenzyl-methylammonium, NBz3MeAcO (Al, Bu, Bz, Me, AcO refer to allyl, 1-butyl, benzyl, methyl and acetate group, respectively). We observed the following MCC dissolution order (given as wt%): NBu4AcO > NAl2BzMeAcO > NBz3MeAcO ≫ NBzMe3AcO. To explain this result we used the combined data of: (1) solvatochromism to calculate the following binary solvent (b-solvent) descriptors that are important for MCC dissolution: empirical polarity, Lewis acidity, Lewis basicity, dipolarity, polarizability; (2) isothermal titration micro-calorimetry to calculate the enthalpy of interaction (ΔH) of β-cyclodextrin (cellulose model) with QAAcO/DMSO-acetonitrile; (3) molecular dynamics simulations to calculate solvent-induced separation of cellulose chains; average number of hydrogen bonds between acetate ions and cellulose OH-groups, and average composition of the biopolymer solvation layer. We offer the following pieces of evidence to show the importance of hydrogen bonding for the efficiency of cellulose dissolution: the orders of b-solvent basicity and of |ΔH| are parallel to its cellulose dissolution efficiency; the biopolymer solvation layer of efficient b-solvents (e.g., NBu4AcO-DMSO) contains more ionic liquid ions and less DMSO molecules than that of NBz3MeAcO, leading to pronounced biopolymer chain separation, hence eventual dissolution. Our approach shows the power of the combined use of several techniques to rationalize the requirements for efficient cellulose solvents.Graphic abstract
Water Regime Effects on Phosphorus Mobility and the Performance of Liquid Phosphorus Fertilizers in Contrasting Soils
The behavior of phosphorus (P) fertilizers in soil is governed not only by fertilizer solubility, but also by P mobility and vertical redistribution within the soil profile under contrasting water regime. This study aimed to investigate the combined effects of water regime, fertilizer type, and soil properties on the vertical redistribution of ammonium acetate–lactate extractable phosphorus (P-AL) in the surface soil layer under controlled pot conditions. Experiments were conducted using three soils with contrasting chemical properties: AC-LO (acidic loam, pH 5.9), NE-CL (neutral clay loam, pH 6.8), and AL-SL (alkaline sandy loam, pH 8.0). Four simulated rainfall regimes were applied at a constant rate of 25 mm day−1, corresponding to cumulative water inputs of 0 mm (W0), 50 mm (W50), 100 mm (W100), and 150 mm (W150). Fertilizer treatments included an unfertilized control (NF), a liquid NP 4–18 fertilizer applied at a low dose (L1), a liquid NP 4–18 fertilizer applied at a high dose (L2), and a solid NPK 15–15–15 fertilizer (S). Water regime exerted the strongest control on P mobility, with P-AL increasing by approximately 40–60% from W0 to W150, depending on soil type. In AC-LO, strong P fixation under low moisture minimized differences among fertilizer treatments, whereas under higher moisture (W100–W150), liquid fertilizers—particularly L2—resulted in P-AL levels approximately 10–30% higher than those of the solid fertilizer. In NE-CL, P mobility was moderate and, under W100–W150, L2 produced P-AL values approximately 10–15% higher than the solid fertilizer, promoting a more uniform P redistribution within the 2–8 cm layer. In AL-SL, the response under wet conditions depended on the water regime: at W100, L2 generated P-AL values comparable to the solid fertilizer, whereas at W150, L2 increased P-AL by approximately 11% relative to the solid form. Overall, the results indicate that soil chemical properties primarily regulate the extent of phosphorus redistribution, while water regime controls its intensity and fertilizer form influences the initial spatial configuration of P within the surface soil layer. The findings provide mechanistic insight into short-range phosphorus transport in soil, without allowing direct inferences regarding agronomic efficiency or crop response.
Modelling of polyphenol and flavonoid extraction from bottle gourd fruit using green and cost effective LTTM glycerol-ammonium acetate in neat and diluted forms
The current study investigated the effectiveness of a low-cost, safe and green LTTM (low-transition-temperature mixture) GAA (glycerol-ammonium acetate) for extraction of bioactive biomolecules form bottle gourd (Lagenaria siceraria) fruit. Two forms of LTTM, neat and diluted with ethanol, were compared. Response surface methodology (RSM) was employed for optimization using the Box-Behnken design consisting of three-factors, each with three levels. Total polyphenols (TP), total flavonoids (TF), anti-radical activity (ARA), and iron chelating activity (ICA) were dependent variables, while time, temperature, speed, and solvent concentrations were independent variables. Second order polynomial models were well fitted for the responses in both solvent systems. For GAA-ethanol extraction, TP, TF, ICA, and anti-radical activity were 14.47 mg GAE/g, 4.93 mg RE/g, 12.21% and 36.43%, respectively, at optimum conditions of extraction time (42 min), temperature (42 °C), and solvent ratio (56%). For GAA extraction, the values 4.50 mg GAE/g, 2.86 mg RE/g, and 70.21% were obtained for TP, TF, and anti-radical activity, respectively, at optimized extraction conditions of speed 300 RPM, temperature 50 °C and solvent-to-solid ratio 10 mL/g. For anti-radical activity of GAA and GAA-ethanol extracts, the error rates between predicted and observed values were extremely low (3.35% and 3.88%, respectively), which demonstrated the suggested quadratic polynomial models as adequate for predicting this activity under any set of extraction conditions. With the error rate of 15.09%, the extraction of TP with GAA can also be quite adequately modelled. The study demonstrated GAA as a green and efficient solvent for extraction of polyphenols and other antioxidant biomolecules from L. siceraria fruit and the optimized process can be used for maximum extraction of antioxidants from it.
Sequential Extraction of Potentially Toxic Metals: Alteration of Method for Cu-Ni Polluted Peat Soil of Industrial Barren
An evaluation of fraction composition and transformation of metal compounds emitted by metal ore processing enterprises and accumulated in soils is crucial for assessing the environmental risks of pollution and ecosystem benefit of remediation. The aim of this study was to develop a suitable sequential fractional procedure for metal pollutants for the peat soils matrix in the impact zone of a Cu-Ni smelter. Three experiment series were performed: (a) the study of the effect of ammonium acetate buffer pH in the range of 3.7–7.8 on the soil metal extraction; (b) the study of the effect of additional volume and frequency of soil treatment with solutions on the content of water-soluble, ammonium acetate extractable, and 0.1 N HNO3 extractable fractions; and, (c) the determination of the metal fraction composition in the modified technique. Soil treatment with ammonium acetate buffer with a pH range of 4.5–5.5 was the most appropriate for the determination of mobile compounds of Cu and other metals in highly polluted peat soil. Triple soil treatment with water and ammonium acetate is necessary for the complete extraction of the water-soluble and exchangeable fractions, respectively. Additionally, we propose a procedure of full extraction of the exchangeable metal fraction from peat soils while using single treatment with 0.1 N HNO3. This scheme allows evaluating geochemical mobility of metals and current environmental harm of polluted soils with a high content of organic matter.
Effect of Zinc Ammonium Acetate on Characteristics of Timothy Canopy and Seed Yield
The purpose of the experiment was to assess the effect of application of zinc ammonium acetate (ZAA) on yielding, morphological features and on selected vegetation indices of timothy cv. ‘Owacja’ cultivated for seeds. Zinc ammonium acetate that has a biostimulatory effect was used foliar in the carried out experiment. The experiment was conducted in the years 2015-2017 at the experimental station in Prusy near Krakow, a part of the Experimental Station of the Institute of Crop Production of the University of Agriculture in Krakow. The field experiment was set up in a randomized block design, in four replications, and the area of experimental plots was 10 m2. Degraded Chernozem formed from loess (classified to the first class quality soil) was present on the experimental area. The experiment consisted in applying ZAA as spray at three doses: 0.214, 0.267 and 0.400 kg(ZnNH4(CH3CO2)3)/ha. Based on the obtained preliminary results, it was found that application of foliar activator in a higher dose (0.400 kg/ha) caused a significant (p ≤ 0.05) increase in seed yield, 1000-seed weight and in germination capacity in relation to the control. Improvement in morphological properties was also observed. Leaf greenness index (SPAD) was also determined. Its highest value was found in plants from the treatment where the highest dose of the zinc ammonium acetate was applied. Seeds obtained from plants treated with ZAA were riper (ripeness was measured with 1000-seed weight) and had higher germination capacity in relation to control treatments.
An acetate electrolyte for enhanced pseudocapacitve capacity in aqueous ammonium ion batteries
Ammonium ion batteries are promising for energy storage with the merits of low cost, inherent security, environmental friendliness, and excellent electrochemical properties. Unfortunately, the lack of anode materials restricts their development. Herein, we utilized density functional theory calculations to explore the V 2 CT x MXene as a promising anode with a low working potential. V 2 CT x MXene demonstrates pseudocapacitive behavior for ammonium ion storage, delivering a high specific capacity of 115.9 mAh g −1 at 1 A g −1 and excellent capacity retention of 100% after 5000 cycles at 5 A g −1 . In-situ electrochemical quartz crystal microbalance measurement verifies a two-step electrochemical process of this unique pseudocapacitive storage behavior in the ammonium acetate electrolyte. Theoretical simulation reveals reversible electron transfer reactions with [NH 4 + (HAc) 3 ]···O coordination bonds, resulting in a superior ammonium ion storage capacity. The generality of this acetate ion enhancement effect is also confirmed in the MoS 2 -based ammonium-ion battery system. These findings open a new door to realizing high capacity on ammonium ion storage through acetate ion enhancement, breaking the capacity limitations of both Faradaic and non-Faradaic energy storage. Ammonium ion batteries are of growing interest for energy storage research. Here, the authors observe two-step pseudocapacitive storage behavior in an ammonium acetate electrolyte, resulting in a superior ammonium ion storage capacity.
Significant improvement of spray pyrolyzed ZnO thin film by precursor optimization for high mobility thin film transistors
Metal-oxide thin-film transistors (TFT) fabricated by spray pyrolysis are of increasing interest because of its simple process and scalability. A bottleneck issue is to get a bubble-free and dense material. We studied the effect of ammonium acetate (AA) addition in the oxide precursor solution on the performance of spray-coated ZnO TFTs. AA acts as a stabilizer, which increases the solubility of the solution and enhances the film quality by reducing the defects. With AA addition in ZnO precursor, the films are coffee ring free with high mass density and better grain orientation. The ZnO TFT with AA exhibit a remarkable improvement of its device performance such as saturation mobility increasing from 5.12 to 41.53 cm 2 V −1 s −1 , the subthreshold swing decreasing from 340 to 162 mV/dec and on/off current ratio increasing from ~10 5 to 10 8 . Additionally, the TFTs show excellent stability with a low threshold voltage shift of 0.1 V under gate bias stress. Therefore, the addition of AA is a promising approach to achieve high-performance ZnO TFTs for low-cost manufacturing of displays.
Hyperammonemia in cirrhosis induces transcriptional regulation of myostatin by an NF-κB–mediated mechanism
Loss of muscle mass, or sarcopenia, is nearly universal in cirrhosis and adversely affects patient outcome. The underlying cross-talk between the liver and skeletal muscle mediating sarcopenia is not well understood. Hyperammonemia is a consistent abnormality in cirrhosis due to impaired hepatic detoxification to urea. We observed elevated levels of ammonia in both plasma samples and skeletal muscle biopsies from cirrhotic patients compared with healthy controls. Furthermore, skeletal muscle from cirrhotics had increased expression of myostatin, a known inhibitor of skeletal muscle accretion and growth. In vivo studies in mice showed that hyperammonemia reduced muscle mass and strength and increased myostatin expression in wild-type compared with postdevelopmental myostatin knockout mice. We postulated that hyperammonemia is an underlying link between hepatic dysfunction in cirrhosis and skeletal muscle loss. Therefore, murine C2C12 myotubes were treated with ammonium acetate resulting in intracellular concentrations similar to those in cirrhotic muscle. In this system, we demonstrate that hyperammonemia stimulated myostatin expression in a NF-κB–dependent manner. This finding was also observed in primary murine muscle cell cultures. Hyperammonemia triggered activation of IκB kinase, NF-κB nuclear translocation, binding of the NF-κB p65 subunit to specific sites within the myostatin promoter, and stimulation of myostatin gene transcription. Pharmacologic inhibition or gene silencing of NF-κB abolished myostatin up-regulation under conditions of hyperammonemia. Our work provides unique insights into hyperammonemia-induced myostatin expression and suggests a mechanism by which sarcopenia develops in cirrhotic patients.
Addressing a Common Misconception: Ammonium Acetate as Neutral pH “Buffer” for Native Electrospray Mass Spectrometry
Native ESI-MS involves the transfer of intact proteins and biomolecular complexes from solution into the gas phase. One potential pitfall is the occurrence of pH-induced changes that can affect the analyte while it is still surrounded by solvent. Most native ESI-MS studies employ neutral aqueous ammonium acetate solutions. It is a widely perpetuated misconception that ammonium acetate buffers the analyte solution at neutral pH. By definition, a buffer consists of a weak acid and its conjugate weak base. The buffering range covers the weak acid pK a ± 1 pH unit. NH 4 + and CH 3 -COO − are not a conjugate acid/base pair, which means that they do not constitute a buffer at pH 7. Dissolution of ammonium acetate salt in water results in pH 7, but this pH is highly labile. Ammonium acetate does provide buffering around pH 4.75 (the pK a of acetic acid) and around pH 9.25 (the pK a of ammonium). This implies that neutral ammonium acetate solutions electrosprayed in positive ion mode will likely undergo acidification down to pH 4.75 ± 1 in the ESI plume. Ammonium acetate nonetheless remains a useful additive for native ESI-MS. It is a volatile electrolyte that can mimic the solvation properties experienced by proteins under physiological conditions. Also, a drop from pH 7 to around pH 4.75 is less dramatic than the acidification that would take place in pure water. It is hoped that the habit of referring to pH 7 solutions as ammonium acetate “buffer” will disappear from the literature. Ammonium acetate “solution” should be used instead. Graphical Abstract ᅟ
Microwave-assisted preparation of polysubstituted imidazoles using Zingiber extract synthesized green Cr2O3 nanoparticles
Cr 2 O 3 nanoparticles were prepared using Zingiber officinal extract which were used as an efficient and reusable catalyst in the practical synthesis of polysubstituted imidazoles by means of a convenient reaction of aromatic aldehydes with ammonium acetate and benzil under microwave irradiation and H 2 O as solvent. The structure of the compounds was studied by IR and 1 H-NMR spectrum. The most important benefits of this process are operational simplicity, reasonable reaction times, and excellent yield of products. The results show that the optimal conditions for the formation of imidazole derivatives are as follow: power of 400 W, reaction time of 4–9 min, H 2 O as a solvent, and 15 mmol of catalyst amount.