Concentrated Salt Solutions Research Articles

Experimental Investigation on the Effect of Salt Solution on the Soil Freezing Characteristic Curve for Expansive Soils

With the development of the Belt and Road Initiative in China, high-speed railways are booming and inevitably pass through seasonal frost regions. In Nanyang basin, due to seasonal changes, railway subgrades will undergo frost heaving and thawing subsidence. The freezing characteristics of the soil are characterized by the freezing characteristic curve, and the important factors affecting the freezing characteristic curve are the content of expansive clay minerals in the soil and the salt solution. Therefore, three soil samples with different montmorillonite contents were saturated with salt solutions of different concentrations, and the freezing temperature of the soil samples was controlled by a cold bath. After the temperature equilibrium, the frozen stable soil samples were put into a nuclear magnetic resonance instrument to test the unfrozen water content, and the relationship between the freezing temperature and the unfrozen water content of expansive soil under different salt solution concentrations was obtained. Additionally, a unified model was used to simulate the test results. The results show that SFCC shifts to the left, that is, the sodium chloride salt solution reduces the freezing point of the soil sample so that it has more unfrozen water at the same temperature. At the same time, the soil’s freezing characteristic curves are closely related to content of expansive clay minerals in the soil. The more expansive clay mineral content, the greater the corresponding unfrozen water content. These results provide some basic insights for improving the frost heave and thaw subsidence problems of railway subgrades in seasonal permafrost regions, which will have a positive impact on promoting the management and rational application of land resources and the promotion of sustainable development.

Controllable synthesis of multi-tip spatial gold nanostructures to facilitate SPR enhancement for exosomal PD-L1 assay

A surface plasmon resonance (SPR) biosensor was developed utilizing gold nanoflowers with multi-tip tiny petals (Au@Au mNFs) and multifunctional peptides for the selective detection of exosomal programmed cell death 1 ligand 1 (ExoPD-L1). In the presence of different salt concentrations, DNA-functionalized gold seeds underwent in situ gold growth, resulting in Au@Au NFs with varying numbers of petals or Au@Au nanospheres (Au@Au NSs). The growth orientation of the gold shells was influenced by the “upright”, “tilted” or “lying” state of the DNA on the gold core surface, depending on the salt concentration solution. The finally prepared Au@Au mNFs exhibited a multi-tip spatial structure, which served as a highly efficient SPR sensitized layer with abundant hot spots on the gold film surface. The enhanced SPR sensitivity was attributed to the substantial electromagnetic field enhancement generated at the tips of the mNFs. By achieving suitable surface coverage of the multifunctional peptide at the sensing interface constructed by Au@Au mNFs, efficient capture of ExoPD-L1 was ensured. The analysis results demonstrated that the developed SPR sensor successfully detected ExoPD-L1 within a concentration range of 10–107 particles/mL, with a detection limit of 4.95 particles/mL. This work highlights the significant improvement in SPR sensing and detection performance achieved by utilizing Au@Au mNFs with multi-tip spatial nanostructures, providing a straightforward approach for achieving ultra-sensitive detection of target substances through SPR.

The effect of maltodextrin on properties of sated egg yolk

Salted eggs are mainly produced through salting treatments that taste salty. However, high sodium intake is part of the pathophysiology of hypertension. Thus, this study aimed to develop low-sodium egg yolks with salting treatment using sodium chloride (NaCl) and maltodextrin to reduce salt content in the salting process. Salted egg yolks were produced using methods in the salting process using maltodextrin (10% and 20% supplement) and were compared to salted eggs brined with 20 and 26% sodium chloride (NaCl) solutions. The moisture content, salt content, color, and texture properties of salted egg yolks during salting for up to 35 days were determined. Nevertheless, salted egg yolks produced with the salting solution using maltodextrin supplement had a significant salt content (0.21-3.30 mg/g) that was lower than the amount discovered in commercial salted yolks (2.84-4.15 mg/g). The results revealed that the maltodextrin substitution affected the salted yolks' properties. The salt contents of all salted egg yolk samples gradually increased during the salting process, along with slight decreases in moisture content as salting time and salt solution concentration increased. The lightness (L*) and the yellowness (b*) decreased while the redness (a*) increased. The hardness, adhesiveness, cohesiveness, gumminess, and chewiness of salted egg yolks increased rapidly over the time of salting, while springiness decreased during the initial stages of salting and reached almost constant levels at the end of salting. As the salting time increased to 35 days, the salted yolk gradually became dark reddish. The maximum denaturation temperature (Tmax) and denaturation enthalpy (DH) of egg proteins increased with increasing salting time. These effects were most pronounced due to the high maltodextrin content of the salting solution. This study suggests that this approach with maltodextrin substitution using the shell egg salting protocol can produce low-sodium salted eggs.

Vertical porous aerogel based on polypyrrole and bimetallic modified β-cyclodextrin polymer-chitosan for efficient solar evaporation

Solar-driven interfacial evaporation (SDIE) stands out as a prospective technology for freshwater production, playing a significant role in mitigating global water scarcity. Herein, a cyclodextrin polymer/chitosan composite aerogel (PPy-La/Al@CDP-CS) with vertically aligned channels was prepared as a solar evaporator for efficient solar steam generation. The vertically aligned pore structure, achieved through directional freezing assisted by liquid nitrogen, not only improves water transport during evaporation but also enhances light absorption through multiple reflections of sunlight within the pores. The polypyrrole particles sprayed on the surface of the aerogel acted as a light-absorbing layer, resulting in an impressive absorbance of 98.15 % under wetting conditions. The aerogel has an evaporation rate of 1.85 kg m−2 h−1 under 1 kW m−2 irradiation. Notably, the vertical pore structure of the aerogel allows it to exhibit excellent evaporation performance and salt resistance even in highly concentrated salt solutions. Furthermore, this aerogel is an excellent solar-driven interfacial evaporator for purifying seawater and fluoride-containing wastewater. This photothermal aerogel has the advantages of excellent performance, low cost, and environmental friendliness, and thus this work provides a new approach to the design and fabrication of solar photothermal materials for water treatment.

Dynamic Evolution of Coal Pore-Fracture Structure and Its Fractal Characteristics under the Action of Salty Solution

The instability and failure of coal pillars is one of the important factors leading to the catastrophic consequences of coal mine goaf collapse. Coal mine water has the characteristics of high salinity. Long-term mine water erosion can easily deform the coal pillar structure, eventually leading to instability and damage. This study carried out tests on coal samples soaked in salt solutions with different concentrations, and the nuclear magnetic resonance (NMR) method was used to obtain the dynamic evolution of the pore-fracture structure of coal. On the basis of fractal theory, the changes in fractal dimension of pore structure during the soaking process were discussed. The damage variable based on the pore fractal dimension was defined and the evolution relationship between the damage variable and immersion time was characterized. The findings demonstrated that the porosity change rate has an exponentially increasing relationship with the immersion time, and with the increasement of concentration of salt solution, the porosity change rate also shows increasing trends. The number of seepage pores and total pores increased with the immersion time. While, with the extension of soaking time, the number of adsorption pores first increased and then decreased. The connectivity between pores was enhanced. The relationship between the fractal dimension and the immersion time is linearly decreasing. The damage variable showed an increasing trend with the immersion time. As the concentration of salt solution increased, the damage of coal increased. The research results are of great significance for rationally evaluating the stability of coal pillars and ensuring the safe operation of underground engineering.

Development of Durable Large-Sized CO2 Electrolysis Cells for Industrial Applications

Utilization of carbon dioxide (CO2) as a feedstock of valuable chemicals is necessary to achieve carbon neutrality. Toshiba is developing the low-temperature zero-gap type CO2 electrolysis cells to produce carbon monoxide (CO) [1,2]. CO can further be converted into various chemicals and fuels by catalytic reactions with hydrogen. To make the CO2 electrolysis technology industrially feasible, it is necessary to establish high-throughput system by expanding the electrode area and stacking the cells. Large-sized cells and stacks often suffer from low Faradaic efficiency for the CO production, which is related to insufficient and nonuniform supply of reactant CO2 gas to the cathode reaction sites. This time we focused on the development of large-sized single cells and fabricated an electrolysis cell with 400 cm2 electrodes. With properly designed gas flow plates and gaskets, the cell voltage and the CO Faradaic efficiency of the fabricated cell at a current density of 400 mA cm-2 were comparable to those of the previously developed smaller cells with 4 cm2 electrodes. The CO concentration in the cathode outlet gas reached ca. 80% by controlling the inlet CO2 flow rate. Stability is another essential property of CO2 electrolysis cells required for the industrial application. Cathode flooding and salt precipitation are major stability issues characteristic of relatively short-term operations, whose detailed mechanism is still in debate [3]. To mitigate those stability issues, we focused on the cathode inlet humidity and the pressure difference between the cathode and the anode. The former is related to the salt concentration in electrolyte solution around the cathode reaction sites, and the latter is related to the convection of electrolyte from the anode side to the cathode side. By controlling those parameters, stable performance over 100 h was achieved.Part of this work was commissioned by Ministry of the Environment, Government of Japan.[1] Y. Kofuji, A. Ono, Y. Sugano, A. Motoshige, Y. Kudo, M. Yamagiwa, J. Tamura, S. Mikoshiba, and R. Kitagawa, Chem. Lett., 50, 482-484 (2021).[2] Y. Kiyota, Y. Kofuji, A. Ono, S. Mikoshiba, and R. Kitagawa, 242nd ECS Meeting, I05-1942 (2022).[3] M. Sassenburg, M. Kelly, S. Subramanian, W. A. Smith, and T. Burdyny, ACS Energy Lett., 8, 321-331 (2023).

Ion Concentration-Dependent Surface Charge Density Inside a Nanopore.

Surface charges shape the electrical double layer (EDL) structure at solid-liquid interfaces, critically influencing the performance of energy storage and micro/nanofluidic devices. However, accurately measuring surface charge density in nanoconfined spaces continues to be a challenge. Here, we introduce a methodology via solid-state nanopores that can investigate the dependence of surface charge density on salt concentrations and nanopore diameters. Measurements, complemented by a theoretical model, reveal that the surface charge density decreases as both the salt concentration in bulk solutions and the nanopore sizes are reduced. Notably, when the salt concentration in the bulk solution drops below 10-3 M, protons dominate ion conductance in a nanopore, resulting in a constant surface charge density. This study introduces an effective approach to surface charge characterization and may serve in the design of electrokinetically driven nanofluidic systems.

Ultrahigh separation property of GO membrane for dissolved organic compound in high-salt brine

The membrane separation technology for the removal of dissolved organic compounds still faces numerous challenges in concentrated salt solution. In this work, the GO/PES membrane was successfully fabricated only adjusting the pH value without any cross-linking agent. The morphology, surface charge distribution, and separation performances were characterized in detail. Results demonstrated the GO/PES membrane exhibited excellent separation performances for tributyl phosphate, sulfonated kerosene and bis(2-ethylhexyl) phosphate with the corresponding flux of 630, 560 and 600 L‧m−2‧h−1, and separation efficiency of 93.1 %, 95.6 % and 96.5 %, respectively, exhibiting both high selectivity and permeability. Meanwhile, the GO/PES membrane exhibited almost 100 % separation efficiency with flux of 1430 L‧m−2‧h−1 for methylene blue solution. Impressively, the GO/PES membrane showed ultrahigh separation efficiency for 200 Da without influences on ions when the salt content was 327 g‧L−1. Furthermore, the GO/PES membrane exhibited robust structural stability and excellent separation performances, which can endure 2000 times folds and corrosion in HCl, NaOH and NaCl for two weeks without separation performances decline. This study highlighted the broad application prospects in the treatment fields of high-salt solution.

Ambient aerosols increase stomatal transpiration and conductance of hydroponic sunflowers by extending the hydraulic system to the leaf surface

IntroductionMany atmospheric aerosols are hygroscopic and play an important role in cloud formation. Similarly, aerosols become sites of micro-condensation when they deposit to the upper and lower surfaces of leaves. Deposited salts, in particular can trigger condensation at humidities considerably below atmospheric saturation, according to their hygroscopicity and the relative humidity within the leaf boundary layer. Salt induced water potential gradients and the resulting dynamics of concentrated salt solutions can be expected to affect plant water relations.MethodsHydroponic sunflowers were grown in filtered (FA) and unfiltered, ambient air (AA). Sap flow was measured for 18 days and several indicators of incipient drought stress were studied.ResultsAt 2% difference in mean vapor pressure deficit (D), AA sunflowers had 49% higher mean transpiration rates, lower osmotic potential, higher proline concentrations, and different tracer transport patterns in the leaf compared to FA sunflowers. Aerosols increased plant conductance particularly at low D.DiscussionThe proposed mechanism is that thin aqueous films of salt solutions from deliquescent deposited aerosols enter into stomata and cause an extension of the hydraulic system. This hydraulic connection leads – parallel to stomatal water vapor transpiration – to wick-like stomatal loss of liquid water and to a higher impact of D on plant water loss. Due to ample water supply by hydroponic cultivation, AA plants thrived as well as FA plants, but under more challenging conditions, aerosol deposits may make plants more susceptible to drought stress.

Flexible layered double hydroxides array composite membrane for efficient pervaporation desalination

Pervaporation has been considered a promising technique in seawater desalination. Developing new and efficient pervaporation membrane material remains the main challenge. In this study, the layered double hydroxides (LDH) nanosheet array composite membranes were prepared on a commercial polyacrylonitrile ultrafiltration membrane through the hydrothermal method. The structure and morphology of the LDH array was regulated by the hydrolysis of the substrate and the hydrothermal conditions. The obtained LDH composite membrane had a good pervaporation desalination performance due to its unique water molecular transport channel and high hydrophilicity. When the salt concentration in the feed solution increased from 3 to 10 wt%, the rejection of the composite membrane could maintain at 99.8 %. The real seawater was also used to evaluate the membrane. The results indicated the LDH composite membrane had a good desalination performance in a relatively wide range. Moreover, the LDH composite membrane exhibited excellent flexibility and stability. We anticipated that the membrane may have great potential in pervaporation desalination.

Effect of operation conditions on particulate matter removal by a packed-bed wet scrubber for a small-scale biofuel boiler

In 2013 the EU’s Clean Air Policy Package was established, aiming to reduce air pollution to half by 2030 compared to the level in 2005. Small-scale (<500 kW)biofuel boilers play a key role in particulate matter emission, and exposure to particulate matter even in the short term can cause different diseases. With the aim of reducing particulate matter emission in Europe, this study presents an approach to improve the removal of particulate matter emitted by small-scale boilers. A biofuel combustion boiler was equipped with a packed-bed wet scrubber, and the flue gas emitted through combustion was cleaned through the wet scrubber using a saltwater mixture. The performance of a packed-bed wet scrubber was investigated under different operating conditions. The effect of the salt concentration of the absorption solution, the temperature of the absorption solution fed to the absorber, and the height of the packed-bed material on the particle collection efficiency were measured. The operating conditions were selected based on the results obtained in a previous computational fluid dynamic simulation study. The results obtained in the present study show that an absorption solution temperature of 30 °C and an absorption solution concentration of 75 % with a full height of the packed-bed material lead to the best performance in the system. Totally keeping the absorption solution temperature as low as possible, increasing the absorption solution concentration, and raising the packed-bed material height could improve the particle collection efficiency by enhancing the effect of the diffusiophoresis and thermophoresis forces and the contact time between the flue gas and solution.

Thermo-pH-Salt Environmental Terpolymers Influenced by 2-((Dimethylamino)methyl)-4-methylphenyl Acrylate: A Comparative Study for Tuning Phase Separation Temperature.

This study offers a comparison between three different types of thermoresponsive (TR) and thermo-pH-salt (TPR) multiresponsive polymers including homopoly(N-isopropylacrylamide) (PNIPAAm), copolymers with three different monomers, 2-hydroxyethyl methacrylate (HEMA), N,N-dimethylacrylamide (DMAAm), and styrene (S) at three different concentrations (5, 10, and 20 mol %), and a PNIPAAm terpolymer with 5, 10, and 20 mol % 2-((dimethylamino)methyl)-4-methylphenyl acrylate (DMAMCA) and 10 mol % HEMA, DMAAm, and S monomers. All polymers were chemically analyzed with 1H NMR and Fourier transform infrared spectroscopy (FT-IR) as well as gel permeation chromatography (GPC) for the molecular weights and dispersity and differential scanning calorimeter (DSC) for the glass transition temperatures. The cloud point, also known as the phase separation temperature (Cp), was determined for all polymers by a turbidity test using a UV-vis spectrophotometer; a micro-differential scanning calorimeter was used for measuring the cloud point in deionized water. The influence of a tertiary amine cationic group of DMAMCA changed the behavior of TR copolymers into TPR by shifting the cloud point of the TPR to higher values in acidic solutions (lower pH) and to lower values in alkaline solutions. The Cp was measured at different concentrations of Hofmeister kosmotropic and chaotropic anion salt solutions in a range of pH solutions for the terpolymers. It demonstrated the same behavior as mentioned in pH solutions besides the effect of salt ions. By measuring the Tc and Cp of these polymers, we can exploit various applications of stimuli-responsive materials for sensors and biomedical technology.

Study on the supercooling and crystallization mechanism of saline soil based on thermodynamic framework

Quantifying the supercooling characteristics of saline soil–water systems is essential for engineering and agriculture in cold regions. However, the crystallization mechanism of supercooling remains unclear. We conducted experimental observations to investigate the impact of salinity on the soil supercooling properties. Additionally, a freezing nucleation thermodynamic model for saline soil was established based on the Negentropic Nucleation Framework (NNF). Statistical analysis methods were employed to analyze the sensitivity of the parameters and interpret the supercooling microscopic mechanism. The results indicated that the supercooling degree distribution of saline soil is best described by a normal distribution (hypothesis testing statistic Dn=0.176). The nucleation rate was primarily controlled by water activity and activation energy of water molecules. The concentration of salt solution played a crucial role in promoting the formation and growth of crystal nuclei. However, the promoting effect decreased with increasing solution concentration when the concentration was below 0.3 mol/L. Moreover, the nucleation potential energy barrier increased with salt concentration, with NaCl environment exhibiting a higher nucleation potential energy barrier compared to Na2SO4 environment at the same salt concentration. In summary, this research provides a theoretical reference for revealing the freezing-thawing hysteretic mechanism and improving the accuracy of numerical calculation models in cold regions.

Germination Strategy of Chenopodium acuminatum Willd. under Fluctuating Salinity Habitats

Germination events of plants often occur after rainfall in saline environments where the soil salinity is diluted, viz recovery germination. Previous germination studies have rarely considered the duration of exposure to salt stress, and none of them have investigated recovery germination under low-salt concentration, other than in distilled water. The main objective of this study was to investigate the effects of salinity, exposure duration and low-salt recovery solutions on seed germination of the weed Chenopodium acuminatum to get a clear insight about the germination strategy exhibited by this species in a saline habitat. Seeds were initially exposed to 0–400 mM NaCl for 10, 20 and 30 d. The subsequent recovery experiment was conducted differently. For those initially treated with 100 and 200 mM NaCl, the recovery solution was distilled water, while for those initially treated with 300 and 400 mM NaCl, the recovery solution was distilled water, at 50 and 100 mM NaCl. Results showed that the recovery germination percentage and rate significantly decreased when the exposure duration extended. Seeds could subsequently recover to germinate at high percentages at recovery salt solution concentrations for a short duration, but the recovery percentages and rates in high salinity, combined with high exposure duration and relatively high recovery salt concentrations, were remarkably lower. More than 30% of the ungerminated seeds were viable after the recovery experiment. We suggest that Ch. acuminatum exhibits a ‘cautious’ strategy of germination to avoid injury from long-term salt stress and ensure survival for the subsequent continuation of its population under unfavorable saline conditions.

Electrochemical dissolution behavior and electrochemical jet machining characteristics of titanium alloy in high concentration salt solution

Electrochemical dissolution behavior and electrochemical jet machining characteristics of titanium alloy in high concentration salt solution

Analysis of The Characteristics of Porang Flour as A Coating Material After Treatment of NaCl Solution

The application of coatings from natural materials is currently needed to improve the appearance and maintain quality, so that it can support the green economy, namely increasing the welfare and social equality of the farming community. One of the basic ingredients in the manufacture of coatings from the polysaccharide group is konjac flour. The main problems faced in the development of konjac flour as a coating are that the color is still brown and itchy caused to the high content of calcium oxalate. Treatment with NaCl salt is one of the efforts to improve the quality of konjac flour as a coating material. Immersing konjac in NaCl salt solution repeatedly can reduce calcium oxalate. The reason of the observe became to decide the impact of the concentration and time of immersion of konjac slices into the salt solution of NaCl on the characteristics of the resulting konjac flour. This study used a two-factor randomized design, namely the concentration of NaCl salt solution (5, 10, and 15%) and the second factor was the immersion time (15, 30, and 45 minutes). Each treatment combination was repeated three times. The concentration and time of immersion into the salt solution of NaCl affected on color L*, browning index, water content, solubility, and acidity of konjac flour. The best treatment was soaking time of 30 minutes with NaCl concentration of 15%.&#x0D;

Antifouling Coatings from Glassy Polyelectrolyte Complex Films.

Coatings that prevent or decrease fouling are sought for many applications, including those that inhibit the attachment of organisms in aquatic environments. To date, antifouling coatings have mostly followed design criteria assembled over decades: surfaces should be well/strongly hydrated, possess low net charge, and maintain a hydrophilic character when exposed to the location of use. Thus, polymers based on ethylene glycol or zwitterionic repeat units have been shown to be highly effective. Unfortunately, hydrated materials can be quite soft, limiting their use in some environments. In a major paradigm shift, this work describes glassy antifouling films made from certain complexes of positive and negative polyelectrolytes. The dense network of electrostatic interactions yields tough materials below the glass transition temperature, Tg, in normal use, while the highly ionic character of these polyelectrolyte complexes ensures strong hydration. The proximity of equal numbers of opposite charges within these complexes mimics zwitterionic structures. Films, assembled layer-by-layer from aqueous solutions, contained sulfonated poly(ether ether ketone), SPEEK, a rigid polyelectrolyte that binds strongly to a selection of quaternary ammonium polycations. Layer-by-layer buildup of SPEEK and polycations was linear, indicating strong complexes between polyelectrolytes. Calorimetry also showed that complex formation was exothermic. Surfaces coated with these films in the 100 nm thickness range completely resisted adhesion of the common flagellate green algae, Chlamydomonas reinhardtii, which were removed from surfaces at a minimum applied flow rate of 0.8 cm s-1. The total surface charge density of adsorbed cations, determined with a sensitive radioisotopic label, was very low, around 10% of a monolayer, which minimized adsorption driven by counterion release from the surface. The viscoelastic properties of the complexes, which were stable even in concentrated salt solutions, were explored using rheology of bulk samples. When fully hydrated, their Tg values were observed to be above 75 °C.

Environmental-friendly biomass-based Janus ink/urushiol modified cotton fabric for efficient solar-driven interfacial evaporation

Much attention has been paid to the interfacial solar-thermal conversion method for water resource purification. According to the hydrophilicity of ink carbon particles and the amphiphilicity of urushiol molecules (the main compound of Chinese lacquer), a novel environmentally friendly biomass Janus ink/urushiol modified cotton fabric was successfully prepared and exhibited one hydrophilic side and one hydrophobic side through simple immersion and spraying treatments. The Janus fabric displayed excellent water transport behavior, mechanical stability, thermal conductivity, and photothermal conversion performance. Under one stimulated solar radiation, the temperature of the Janus fabric increased to 85 °C in 2 min. Additionally, a photothermal vapor device prepared using a polyethylene ring and the Janus fabric demonstrated a high conversion efficiency of 94.3% with an impressive evaporation rate of 1.64 kg m−2h−1, which was 3.35 times the rate of water evaporation in the absence of the modified fabric. The Janus fabric showed satisfactory resistance to ultraviolet radiation and pH values. After 8 cycles (every 10 h) of exposure to outdoor sunlight, the modified fabric showed a slightly decreased evaporation rate, which could be restored to the previous level by re-spraying ink on the modified fabric. In the concentrated salt solutions, the solar-driven evaporator displayed excellent salt rejection capacity. During the desalination of high-concentration saline water, the Janus fabric showed acceptable diurnal correspondence. After desalination, the water quality reached the required standards for drinking water. In particular, the B3+ content droppingto 0.33 mg L−1(below the thresholdof 0.5 mg L−1). The solar steam generator also showed remarkable purifying capabilities for wastewater containing heavy metals and organic dyes. The Janus ink/urushiol fabric, prepared in an easy way, has a wide range of applications in seawater desalination and sewage treatment, which can be applied for mitigation of freshwater crises and environmental remediation.

Experimental study on preparation of α-hemihydrous gypsum by modification of desulfurized gypsum

In the process of preparing α-hemihydrous gypsum from desulfurized gypsum under atmospheric pressure, the optimum conditions of crystallization transformation and modification of desulfurized gypsum were studied. The effects of the type and concentration of composite salts (CaCl2, KCl, MgCl2 mixed solution) on the crystallization and modification of desulfurized gypsum were studied. The results were further verified by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC/TGA), so as to determine the ideal directional crystallization control index. The experimental results show that temperature, type and concentration of salt solution are the most sensitive factors in the crystallization process of desulfurized gypsum. The optimal control conditions for obtaining α-hemihydrous gypsum with good crystalline form are temperature 95℃~98℃, concentration of composite salt solution (CaCl2: MgCl2: KCl = 25:5:1) is 25%~30%, and slurry concentration is greater than 20%.

Breeding evaluation of the common buckwheat accessions (&lt;i&gt;Fagopyrum esculentum&lt;/i&gt; Moench) obtained with the use of copper and zinc ions

Relevance. Employing new biotechnological methods in the breeding of buckwheat, including the screening of forms with tolerance to copper and zinc ions, might increase the adaptability of genotypes and allow the creation of promising starting material for further breeding.Methods. The research on common buckwheat with tolerance to copper and zinc ions and breeding evaluation of the obtained accessions were conducted at FSBSI «FSC of Agricultural Biotechnology of the Far East named after A.K. Chaiki» in 2020–2023. The research object was 10 accessions obtained from buckwheat varieties Kitavasesoba (Japan) and Izumrud (Russia) and hybrid Izumrud×Kitavasesoba, whose microshoots and seeds were exposed to copper and zinc ions. Released variety Izumrud was used as the standard. The method of cell and tissue culture in vitro as well as the germination of seeds in concentrated solutions of copper and zinc salts in vivo were employed.Results. In the conditions of the monsoon climate of Primorsky Krai, a three-year test of 10 buckwheat samples obtained under the influence of copper and zinc ions in culture in vitro and in vivo was carried out. As a result of the study, three samples were selected for further selection (No. 989, 1013, 783), which are characterized by a complex of economically valuable traits: high seed productivity (6.5–7.1 g), stress resistance, genetic flexibility, high mass of 1000 seeds (37.8–44.8 g), a combination of high mass of 1000 kernels (27.4–33.1 d) with low film content (23.3–25.5%), and two samples (No. 997, 1005) with an increased content of rutin in fruits (7.1–7.7 mg / 100 g).