ABSTRACT At room temperature, the mixture of hydroxylamine nitrate (HAN) solution and polyvinyl alcohol (PVA) powder solidifies to form an electrically controlled solid propellant. Investigating its curing mechanism can provide important guidance for formulation design. This study systematically examines the effects of different HAN solution concentrations, varying PVA contents, and molecular weights on the curing characteristics of the propellant. Multiple characterization techniques, including compression tests, thermogravimetric analysis, Fourier‐transform infrared spectroscopy, and scanning electron microscopy, were employed to thoroughly investigate the curing mechanism of HAN‐electrically controlled solid propellants (HAN‐ECSP). The results indicate that HAN can form stronger hydrogen bonds with PVA, and high‐concentration HAN solutions effectively promote the dissolution of PVA, leading to the formation of a uniform and dense three‐dimensional network structure. This structure not only imparts excellent structural stability to the propellant but also provides good self‐recovery properties. However, low PVA content and molecular weight result in insufficient crystalline regions within the propellant, with inadequate entanglement between PVA chains, which adversely affects the curing performance. To achieve optimal curing performance for HAN‐ECSP, the HAN concentration should be maintained above 80%, the PVA content should be at least 15%, and the PVA molecular weight should exceed 166 000 g/mol.

The reactivity of zinc and chromium (III) oxides, hydroxides and salts (nitrates), as well as the xerogel combustion product (XCP) obtained from a solution of zinc and chromium (III) nitrates with the addition of citric acid, in the reaction of ZnCr2O4 spinel formation was analyzed. Reaction mixtures were prepared by simple mixing of components, as well as under conditions of mechanical activation or microwave processing. Effective constants of reaction rate and product yield were used to estimate the reactivity. A higher rate of the reaction involving hydroxides and salts compared to oxides is shown due to the activation of reagents during thermolysis. It has been established the increased activity of zinc and chromium (III) nitrates and XCP, which was a pre-prepared substance in which the main part of the gases (water vapor, CO2, N2, partially nitrogen oxides) was removed during combustion, leaving the oxide components in an active form, which were subsequently brought into close contact by compression. This distinguished XCP from a mixture of zinc and chromium (III) nitrates, in which gas emission during burning occurred in previously pressed tablets, which reduced the contact area of the reagents. The effect of mechanical activation and microwave treatment of reagents, during which a significant part of the precursors thermolysis took place, was analyzed. The newly formed oxide components actively interacted, and at the final stage of firing, a significant portion of the defects had time to heal. The spinel yield at different temperatures from mixtures consisting of zinc and chromium oxides/hydroxides without machining and after treatment in a planetary mill (PM) was compared, as well as the yield of ZnCr2O4 from mixtures with different preparation methods before burning at a constant temperature (1000 °C, 1 h). The maximum yield was observed when XCP or a mixture of zinc and chromium nitrates were used as precursors. A high reactivity of XCP was noted in the spinel formation without additional pretreatment. With an increase in the burning temperature, the spinel lattice was naturally ordered, which was confirmed by a decrease in the cell parameter and an increase in the size of crystallites. For citation: Filatova N.V., Kosenko N.F., Pavlova K.A., Fedorova G.S. Mechanical and microwave activation of solid-phase synthesis of zinc-chromite spinel. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2026. V. 69. N 3. P. 48-56. DOI: 10.6060/ivkkt.20266903.6885.

Detailed pyrolysis mechanism for ammonium nitrate and ammonium chloride mixtures

Intensive irrigated agriculture relies heavily on nitrogen fertilization, which may cause ammonium accumulation, highly detrimental to sensitive seedlings. Silicon application has emerged as a potential strategy to mitigate this stress, although the underlying mechanisms remain poorly understood. To evaluate this effect, maize seedlings were grown in nutrient solution under five N concentrations (1.4, 3.6, 7.1, 14.3, and 28.6 mmol L−1), applied in the presence or absence of silicon (1.8 mmol L−1 Si). The nitrogen source was a mixture of nitrate and ammonium in a N-NO3−: N-NH4+ ratio of 4:5. Silicon was supplied as monosilicic acid (H2SiO3). Plant growth, leaf area, root morphology (length, diameter, density), N and Si accumulation, uptake and utilization efficiency, SPAD index, nitrate reductase activity, and proline content were evaluated. Silicon supplementation enhanced nitrate reductase activity, SPAD values, leaf area, and root traits, reduced proline in roots and shoots, and improved N uptake and partitioning. Among the tested N concentrations, 14.3 mmol L−1 achieved the highest efficiency of nutrient absorption and biomass production, highlighting silicon as a sustainable strategy to mitigate ammonium stress in maize seedlings.

Eutectic mechanism study for a ternary mixture of sodium, potassium and calcium nitrates and the proposal of a high-performance formulation

There is significant interest in the development of robust and simplified processes for the production of battery materials, including Li(Ni_{0.8}Mn_{0.1}Co_{0.1})O_2 (NMC811), which has demonstrated high energy capacity, thermal stability and excellent electrical conductivity. This study developed a flat-flame reactor to provide a flame environment for flame spray pyrolysis (FSP), starting from an aerosolised solution of a mixture of metal nitrates in water. Preliminary studies were conducted to confirm that the operating conditions produced suitable NMC materials with acceptable performance after annealing at 750 ^{circ }C. Multiple laser diagnostic techniques were applied to characterise the spatial distribution of reactants and products and capture the process of reaction. Phase Doppler particle analysis was used to capture the droplet characteristics of precursors, and Mie scattering was used to map the instantaneous spatial distribution of droplets. A range of excitation wavelengths was tested to detect the participating species. However, only the high-energy wavelengths below 400 nm were capable of eliciting any signal. Light from a 355 nm pulsed laser was used to excite phase-selective laser-induced breakdown spectroscopy (PS-LIBS) to characterise the spatial distribution of the synthesised particles arising from mixing and reaction in the high temperature zone. The excited emission from the reaction zone was spectrally characterised, as was the corresponding time signature. Finally, simultaneous Mie scattering and PS-LIBS images were obtained to capture both droplet and synthesised particle distribution, capturing the emerging reaction process. The studies show, for the first time, how emissions from the formed particles can be used as a surrogate for the progress of reaction in similar FSP systems.

The increasing demand for energy-efficient and environmentally sustainable cooling technologies has led to a renewed focus on ammonia and lithium nitrate-based absorption refrigeration systems, particularly those utilizing Plate Heat Exchangers (PHEs). Despite their importance, reliable predictive models for boiling heat transfer and frictional pressure drop in PHEs using ammonia and lithium nitrate mixtures, such as NH3–LiNO3 and NH3–LiNO3–H2O, remain limited and often suffer from structural deficiencies. This study provides a comprehensive evaluation of existing correlations for boiling heat transfer and friction factor in PHEs, specifically focusing on ammonia-based mixtures (NH3–H2O, NH3–LiNO3, and NH3–LiNO3–H2O). More than 20 correlations for boiling heat transfer coefficient and friction factor were critically analysed and adjusted to account for the unique thermophysical behaviors of multi-component salt mixtures. The study reveals that many correlations fail to accurately predict boiling heat transfer in NH3–H2O mixtures due to inadequate sensitivity to heat flux. Scaling these correlations led to notable improvements in prediction accuracy, underlining the significance of appropriate scaling for different PHE configurations. Additionally, the study validates the assumption that lithium nitrate remains in the liquid phase in NH3–LiNO3 and NH3–LiNO3–H2O mixtures, supporting its exclusion from latent heat calculations. Friction factor correlations that include positive exponents for Reynolds and Weber numbers were found to be structurally inconsistent, resulting in inaccurate predictions. The analysis further highlights that many correlations are overly empirical or based on narrow experimental conditions, limiting their applicability to diverse heat exchanger geometries. A key contribution of this work is the unique visual comparison of the correlations, providing a detailed depiction of their structural characteristics and offering more precise insights than those available in previous studies.

The analysis of the literature, including our works, was carried out, on the basis of which this review article was prepared. Previously, the direct (radiochemical) method proved the participation of nitrate ion in the anodic process - the oxygen evolution reaction (OER). Of interest was the possibility of accepting NO3 radicals formed during electrolysis by other anion-radical particles. Salts of acetic and propionic acids were chosen as model objects. It was found that during electrolysis of acetate-nitrate (system 1) and propionate-nitrate (system 11) mixtures, the pH of the medium significantly affects the selectivity of the reactions. In an acidic medium during electrolysis of both systems at high potentials, nitrate ion acts as a source of active oxygen, which is used to form molecular oxygen and destructively oxidizes alkyl groups. In a weakly alkaline solution, during the electrolysis of an equimolar mixture of system 1, ethane is formed, the current output (CO) of which drops sharply and reaches a value of ~30%, and a small amount of oxygen. A significant part of the current is spent on the oxidation of CH3 particles with the formation of carbon dioxide (CO ~60%) and water. In a weakly alkaline solution, the process of system 11 differs from system 1 and is interesting in that during the electrolysis of an equimolar mixture of propionate and nitrate, products of the interaction of nitrate radicals and propionate particles are formed with the formation of organic nitrates. Based on the analysis of the data obtained by a set of methods, a mechanism for the formation of organic nitrates is proposed.

The synthesis of fine W composite powder with homogeneously dispersed Cu particles was investigated. Commercial or ultrasonic spray pyrolysis WO3 powders were used as source materials of W, and copper nitrate was added and hydrogen-reduced to finally fabricate W-Cu composite powder. The reduced powder prepared using ultrasonic spray pyrolysis WO3 powder exhibited a spherical agglomerate composed of fine particles and pores, whereas that using commercial WO3 showed relatively fine particles with a size of about 200 nm. TEM analysis revealed that Cu elements were uniformly distributed in the composite powder. These results help to optimize the synthesis process of homogeneous W-Cu nanocomposite powders.

BackgroundHumans are widely exposed to mixtures of environmental perchlorate, nitrate, and thiocyanate. However, the associations of perchlorate, nitrate, and thiocyanate with pulmonary function in children were unclear.MethodsTo investigate the associations of urinary perchlorate, nitrate, and thiocyanate concentrations with pulmonary function in children, a total of 2,271 children and adolescents aged 6–19 years with complete data on perchlorate, nitrate, and thiocyanate and pulmonary function were analyzed from the U.S. NHANES 2007–2012. Exposure to perchlorate, nitrate, and thiocyanate was estimated by measuring urinary concentration, and pulmonary function was assessed by spirometry. Linear regression and generalized linear models were performed to estimate the associations of perchlorate, nitrate, and thiocyanate concentrations with pulmonary function measures. Stratified subgroup analyses were performed to examine whether age (6–12 and 13–19 years) and sex differences modified these associations.ResultsIn the overall population, concentrations of perchlorate and nitrate, except for thiocyanate, were associated with a modest decrease in pulmonary function. After stratification by age and sex, those negative associations were more pronounced among the children aged 6–12 years. In children aged 6–12 years, perchlorate concentration was negatively associated with FEV1 (p-trend = 0.04) among boys. In children aged 6–12 years, nitrate concentration was negatively associated with FEV1, FVC, and PEF, respectively (all p-trends < 0.05), in both boys and girls.ConclusionsOur study suggested that exposures to perchlorate, nitrate, except for thiocyanate were associated with impaired pulmonary function in children and adolescents aged 6–19 years, and those associations were more pronounced among children aged 6–12 years. Further replications of the associations in a large prospective cohort study are warranted.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12889-025-23876-w.

This study proposes a novel approach to enhance the performance of solar water heating systems by integrating molten salt thermal energy storage (MSTES) and evaluating its effectiveness under varying tilt angles (15°, 30°, 45°, and 60°). While prior research has extensively explored solar collectors and conventional storage media, there have been limited studies that experimentally assessed the combined effect of MSTES and tilt angle optimization on thermal performance. To address this gap, a parabolic trough collector system is employed using a eutectic mixture of sodium nitrate and potassium nitrate, known for its high thermal stability and energy retention. Key performance metrics, including collector efficiency, heat transfer coefficient, and storage efficiency, are analyzed under different tilt configurations. Results revealed that a 60° tilt angle offered the best performance, achieving a collector efficiency of 75%, a heat transfer coefficient exceeding 880 W m−2 K, and a storage efficiency of 61% during peak solar radiation. These findings highlight the effectiveness of MSTES in maximizing solar energy absorption and storage, thereby contributing to the development of high‐efficiency solar thermal systems that are adaptable to diverse climatic conditions and energy demands.

Salamanders are among the most threatened vertebrates due to chemical and habitat stressors. The Mexican salamander, Ambystoma dumerilii is endemic to Lake Pátzcuaro, Michoacán, Mexico and is exposed to nutrient runoff and discharges from surrounding agriculture and municipal waste. This study evaluated the toxicity of nitrate and phosphate singly and in mixtures to embryonic and the first-stage larval development of A. dumerilii to determine whether measured surface water concentrations comparable to those found in Lake Pátzcuaro pose a risk and whether Mexico's water quality standards are adequate to protect the species. Eggs and larvae of A. dumerilii were exposed for 26 days to nitrate and phosphate individually as well as to dilutions of a mixture based on their LC50 concentrations. The Probit determined LC50 for NO3-N was 887 mg/L and for PO4-P was 2015 mg/L. The LC50 for the mixture was 1.0 toxic unit (TU), while the EC50 for the hatching inhibition mixture was 0.26 TU. Effect thresholds were 0.1 and 0.04 TU respectively. Concentrations of nitrate and phosphate mixtures in selected Mexican surface waters were above the hatching inhibition threshold and the equivalent Mexican standards expressed as mixtures also exceeded this threshold. The toxicity responses to the mixtures suggest that nitrate and phosphate anions compete for the same sites and act in an additive manner. Nitrate and phosphate need to be managed as mixtures rather than singly to protect species with similar sensitivities to A. dumerilii. However, further research is needed to confirm these effects across other aquatic species.

Atmospheric deposition, and agricultural runoff or erosion events have substantially contributed to groundwater pollution throughout the USA. This can become troublesome in states like Wisconsin where 68% of the population rely on groundwater for their drinking water source. As such, exposome research must account for the complexity and frequency of environmental exposures. This study aimed to elucidate chemical-biological interactions and adverse outcome pathways associated with an environmentally relevant mixture of agricultural chemicals detected in Wisconsin groundwater via in vitro and in silico methodologies. Using in vitro models, we determined that a ternary mixture of environmentally relevant concentrations of nitrate, atrazine and imidacloprid resulted in an overt decline in growth rate to the poultry cecal microbiome compared to each chemical singularly. Further, there was a decrease in Caco-2 cell viability in various two-chemical combinations. In silico methods analyzed contaminants detected in Wisconsin groundwater wells from across the state and prioritized two groundwater wells as potential for health concerns. Prioritized chemicals in these groundwater wells were linked to nine gene targets and several adverse outcome pathways. In all, the results demonstrated that there is chemical-biological interaction between these model organisms agricultural and chemical mixtures at real world exposure concentrations.

The construction of an anaerobic digester coupled with post-digestion low-level aeration for agricultural wastewater treatment is described. The digester employs underwater speakers to accelerate the anaerobic digestion process while retaining solids to reduce the strength of the effluent. The effluent is sent to a holding tank and fed at a low flow rate to an aeration tank to effect partial nitrification of the wastewater. The outlet of this tank is sent to a settling tank to retain biomass that developed in the aeration tank, and the effluent is sent to a small constructed wetland to further reduce wastewater nitrogen and phosphorus. The wetland was planted with the broadleaf cattail, Typha latifolia, and hence led to the formation of a retention basin. The system has reduced energy consumption due to the use of underwater sonic treatment and low-level aeration that is not designed to achieve full nitrification/denitrification but rather to achieve a mixture of ammonium, nitrite, and nitrate that might foster the development of a consortium of organisms (i.e., nitrifiers and Anammox bacteria) that can remediate wastewater ammonium at low cost. The system is meant to serve as a complex where various technologies and practices can be evaluated to improve the treatment of agricultural wastewater. Preliminary data from the system are presented.

Cadaver education in health sciences is very important for the professional development of the student. Dead human or animal bodies are used for cadaver training. It is aimed to be used for many years by exposing the bodies to various chemicals immediately after they die, purifying them from microbes and ending autolysis. The chemical formaldehyde is the most common and most easily applicable chemical for this process today. Although widely used, formaldehyde has negative effects on students, employees and the environment. These problems have pushed scientists into different pursuits. In this study, both a cadaver fixation and a cadaver storage solution that can be used in a healthy way instead of formaldehyde were investigated. As a result of the literature review, a solution composition consisting of a mixture of borax, nitrate, nitrite, glycerin, alcohol and thyme oil was created. Half of the seven kidneys, which were brought from the slaughterhouse and divided into two equal halves longitudinally, were left in this solution, and the other half was placed in the 10% formaldehyde solution used for cadaver storage for fixation for one month. When the kidneys were examined after one month, it was observed that the microbial growth in the solution remained low enough not to cause any deterioration. While color changes were at better levels than formaldehyde, texture profile analysis values were found to be closer to fresh kidney tissue. Although the tissue can be recognized at any magnification in histological examinations, it was observed that the cell nuclei received less dye in some sections at x100 magnification. As a result, it was concluded that this solution can be used as a cadaver fixation and storage solution, but more research is needed on it.

Ammonium and nitrate nitrogen are the two main forms of inorganic nitrogen (N) available to crops. However, it is not clear how mixtures of ammonium and nitrate N affect N uptake and partitioning in major rice cultivars in southern China. This study investigated the effects of different ammonium nitrogen and nitrate nitrogen mixture treatments (100:0, 75:25, 50:50, 25:75, and 0:100) on the growth, photosynthetic characteristics, nitrogen uptake, gene expression, and yield of different rice cultivars (Mei Xiang Zhan NO. 2: MXZ2; Nan Jing Xiang Zhan: NJXZ). Rice root biomass, tiller number, and yield were increased by 69.5%, 42.5%, and 46.8%, respectively, in the 75:25 ammonium-nitrate mixed treatment compared to the 100:0 ammonium-nitrate mixed treatment. The nitrogen content in rice roots, stems, leaves, and grains increased by 69.5%, 64.0%, 65.5%, and 17.5%, respectively. In addition, compared with MXZ2, NJXZ had a greater proportion of N allocated to leaves and grains. Analysis of root enzyme activities revealed that the 75:25 ammonium-nitrate mixed nutrient treatment increased rice root glutamine synthetase activity by an average of 35.0% and glutamate synthetase activity by an average of 52.0%. Transcriptome analysis revealed that the 75:25 mixed ammonium-nitrate nutrient treatment upregulated the expression of genes related to the nitrogen metabolism transporter pathway. Weighted correlation network analysis revealed that some differentially expressed genes (HISX and RPAB5) regulated the activities of nitrogen-metabolizing enzymes in rice and some (SAT2, CYSKP, SYIM, CHI1, and XIP1) modulated amino acid synthesis; greater expression of these genes was detected in the 75:25 ammonium-nitrate mixed nutrient treatment. The expression characteristics of the above genes were further confirmed by RT‒qPCR. Interestingly, the expression levels of the above genes were significantly correlated with the glutamate synthase activity, photosynthetic rate, and root volume. It is noteworthy that increasing the expression of the aforementioned genes coupled with nitrogen uptake was observed in the three main rice cultivars. These results suggest that the 75:25 ammonium-nitrate mixture may have increased nitrogen-metabolizing enzyme activities and promoted nitrogen uptake through the upregulated expression of nitrogen metabolism-related genes, thereby increasing tiller number and improving rice yield.

Nitroaromatic compounds are important scaffolds used for the synthesis of a variety of compounds, such as explosives, herbicides, dyes, perfumes and pharmaceuticals. Bismuth nitrate pentahydrate is a widely used reagent in organic synthesis; however, its utility as a nitrating agent for anilines is underexplored. The aim of this work is to propose and find the proper reaction conditions of an alternative nitrating agent constituted by a mixture of bismuth nitrate / acetic anhydride in DCM with a series of substituted anilines under mild reflux. Several anilines having both activating and deactivating substituents in the ortho, meta and para positions were the substrate for the nitration reaction. Experimental conditions were performed in "one-pot" conditions before product purification. Bi(NO3)3•5H2O demonstrated to be effective and somehow regioselective when it came to the nitration of anilines in the ortho position. Although other products were also identified under these conditions, in most cases, the ortho derivative was the major or even the only product obtained with moderate to high yields in the range of 50% - 96%. Bi(NO3)3•5H2O is an efficient and safe nitrating agent since the use of concentrated and corrosive acids like sulfuric and nitric is avoided; furthermore, bismuth nitrate is low-priced and no special care nor equipment is required.

To better understand the application of IVR (In-Vessel Retention), extensive experiments have been conducted on the heat transfer characteristics of molten pool. However, most research mainly focuses on hemispherical lower heads, and the research on ellipsoidal lower head suitable for small pressurized water reactors is relatively lacking. In order to provide some reference for the implementation of IVR with ellipsoidal lower head, this paper conducted the experimental study on the heat transfer characteristics of a three-dimensional double-layer molten pool based on the design of a small pressurized water reactor. The test section consists of two parts: ellipsoidal and cylindrical, with a span of 1150 mm and a total height of 700 mm. The molten material is simulated by nitrate mixture (20mol%NaNO3-80mol%KNO3), and electric heating wire is chosen to simulate the oxide layer decay heat. The effects of heating power, oxide layer height and layered partition thickness on heat transfer characteristics of two-layer molten pool under static conditions were studied. The results show that the thermal stratification phenomenon mainly occurs in the lower and middle regions of the oxide layer, with a smaller dimensionless temperature gradient in the upper region; with the similar volumetric power densities, the height of the oxide layer has little effect on the wall heat flux density; the layered partition increases the thermal resistance between the two layers and reduces the upward heat transfer to the ceramic pool. In addition, the heat transfer relationships in the oxide layer, both downward and upward, are fitted for the internal Rayleigh number range of 3.43 × 1012 to 1.54 × 1013.

Introduction. Microbiological control of preservative solutions and assessment of the state of anatomical preparations are topical issues, the solution of which requires adaptation of methods for quantitative determination of the level of microbial contamination to the special conditions of equilibrium systems containing biological preparations. The aim of the study is screening, experimental testing and adaptation of microbiological methods for quantitative assessment of the level of microbial contamination for monitoring the microbiological purity of preservative solutions using the Melnikov–Razvedenkov solution as an example. Material and methods. The object of the study was the Melnikov–Razvedenkov preservative solution modified by the Scientific Research Center for Biomedical Technologies of the All-Russian Scientific Research Institute of Medicinal and Aromatic Plants. The study used methods for quantitative assessment of the level of microbial contamination on agar nutrient media. Results. As a result of screening, experimental testing and comparative analysis of methods for quantitative assessment of the level of microbial contamination, the most promising methodological approaches were identified and adapted for microbiological monitoring of modified Melnikov-Razvedenkov solution. Conclusions. The microbiological study of the modified Melnikov-Razvedenkov preservative solution showed the feasibility of using the membrane vacuum filtration method with membrane filters made of a mixture of cellulose acetate and nitrate with a nominal pore diameter of 0.45 μm. For sterilization of the test solution, the use of a vacuum filtration through membrane filters with a nominal pore diameter of 0.22 μm is promising.

Purpose: This study aims to develop a cost-effective and environmentally sustainable solar cooking solution for urban and rural populations in developing nations, where the majority rely on non-commercial sources of cooking energy. Design/Methodology/Approach: The research involves designing a solar stove incorporating a thermal battery, heat-storing materials, and a photovoltaic system. Experimental trials were conducted to determine the melting points and density of different heat-storing materials: potassium nitrate, sodium nitrate, and their combination. Findings: The experimental results indicate that a potassium and sodium nitrate mixture provides superior heat storage and release performance compared to the individual components. This combination shows promise for maintaining the necessary temperatures for cooking even in the absence of direct sunlight. Research Limitation: The study is limited to specific heat-storing materials and laboratory-scale experiments, which may differ from real-world conditions. Practical Implication: It could be especially beneficial for off-grid and rural areas in developing countries where traditional fuel sources are scarce or costly. Social Implication: This research offers a renewable energy-based cooking method, improving energy accessibility, health, and quality of life for low-income populations. Originality/Value: It utilises a combination of heat-storing materials that enhances the efficiency and reliability of cooking during off-sunshine hours, distinguishing it from other solar cooking technologies.