Metal Ion Content Research Articles

Hydrogel-Based Sensor for the Detection of Iron Ions and Excessive Alerting.

The excessive content of heavy metal ions in water has attracted increasing worldwide attention due to the potential harm to human health and ecological systems. Therefore, it is particularly significant to research and develop a sensitive and straightforward water quality monitoring method. Here, a dual-network designed hydrogel poly(acrylic acid-co-N-methylolacrylamide)/poly(3,4-ethylenedioxythiophene): polystyrenesulfonate, P(AA-co-N-MA)/PEDOT: PSS, was constructed and used for Fe3+ detection. Compared with previous reports, the P(AA-co-N-MA)/PEDOT: PSS hydrogel has a much more sensitive and convenient detection of immune iron ions (Fe3+), is applied to monitor a trace of over-the-standard (the lower limit of detection is 0.52 ppm corresponding to 0.06 S/m for human health monitor, and the threshold for water quality monitoring is 0.16 S/m). The relationship between Fe3+ content and the conductivity of the hydrogel allows it to integrate with other electron devices to provide an early warning function for Fe3+ in the human body, which would be of great significance to human health monitoring.

Effects of mscM Gene on Desiccation Resistance in Cronobacter sakazakii

Cronobacter sakazakii, an opportunistic foodborne pathogen, has a strong resistance to osmotic stress and desiccation stress, but the current studies cannot elucidate this resistance mechanism absolutely. A mechanosensitive channel MscM was suspected of involving to desiccation resistance mechanism of C. sakazakii. To investigate the specific molecular mechanism, the mscM mutant strain (ΔmscM) was constructed using the homologous recombination method, and the cpmscM complementary strain was obtained by gene complementation, followed by the analysis of the difference between the wild-type (WT), mutant, and complementary strains. Compared to the wild-type bacteria (WT), the inactivation rate of the ΔmscM strain decreased by 15.83% (p < 0.01) after desiccation stress. The absence of the mscM gene led to an increase in the membrane permeability of mutant strains. Through turbidity assay, it was found that the intracellular content of potassium ion (K+) of the ΔmscM strain increased by 2.2-fold (p < 0.05) compared to the WT strain, while other metal ion contents, including sodium ion (Na+), calcium ion (Ca2+), and magnesium ion (Mg2+), decreased by 48.45% (p < 0.001), 24.29% (p < 0.001), and 26.11% (p < 0.0001), respectively. These findings indicate that the MscM channel primarily regulates cell membrane permeability by controlling K+ efflux to maintain the homeostasis of intracellular osmotic pressure and affect the desiccation tolerance of bacteria. Additionally, the deletion of the mscM gene did not affect bacterial growth and motility but impaired surface hydrophobicity (reduced 20.52% compared to the WT strain, p < 0.001), adhesion/invasion capability (reduced 26.03% compared to the WT strain, p < 0.001), and biofilm formation ability (reduced 30.19% compared to the WT strain, p < 0.05) of the bacteria. This study provides a reference for the role of the mscM gene in the desiccation resistance and biofilm formation of C. sakazakii.

Response of Alfalfa Leaf Traits and Rhizosphere Fungal Communities to Compost Application in Saline-Sodic Soil.

Soil salinization is considered a major global environmental problem due to its adverse effects on agricultural sustainability and production. Compost is an environmentally friendly and sustainable measure used for reclaiming saline-sodic soil. However, the responses of the physiological characteristics of alfalfa and the structure and function of rhizosphere fungal communities after compost application in saline-sodic soil remain elusive. Here, a pot experiment was conducted to explore the effect of different compost application rates on soil properties, plant physiological traits, and rhizosphere fungal community characteristics. The results showed that compost significantly increased soil nutrients and corresponding soil enzyme activities, enhanced leaf photosynthesis traits, and ion homeostasis compared with the control treatment. We further found that the rhizosphere fungal communities were dominated by Sodiomyces at the genus level, and the relative abundance of pathogenic fungi, such as Botryotrichum, Plectosphaerella, Pseudogymnoascus, and Fusarium, declined after compost application. Moreover, the α-diversity indexes of the fungal community under compost application rates of 15% and 25% significantly decreased in comparison to the control treatment. The soil SOC, pH, TP, and TN were the main environmental factors affecting fungal community composition. The leaf photosynthetic traits and metal ion contents showed significantly positive correlations with Sodiomyces and Aspergillus. The fungal trophic mode was dominated by Pathotroph-Saprotroph-Symbiotroph and Saprotroph. Overall, our findings provide an important basis for the future application of microbial-based strategies to improve plant tolerance to saline-alkali stress.

Ultrasound-Assisted Community Bureau of Reference (BCR) Procedure for Heavy Metal Removal in Sewage Sludge.

Sewage sludge (SS) resulting from wastewater treatment plants (WWTP) is commonly applied worldwide as a fertilizer in agriculture. This can be done following a rigorous analysis of the sewage sludge composition. Due to its toxic potential, heavy metal ion content is one of the key parameters to test when evaluating SS sample usage as fertilizer. The distribution of metals present in SS samples produced by five municipal WWTPs in Romania was studied. To obtain information regarding metal distribution in SS, a modified ultrasound-assisted extraction procedure of the Community Bureau of Reference (BCR) was employed for As, Cd, Cr, Cu, Mo, Ni, Pb, Zn, and Co quantitation. Concentrations of these metals were measured using ICP-EOS spectrometry. Method extraction accuracy was verified using CRM-483 certified reference material. Results show that extraction efficiency was lowest for the exchangeable fraction for all studied metals. The detected ion metals were found distributed in fractions (F) 2, 3 and 4, which are unavailable for plants and groundwater under natural environmental conditions. One noteworthy finding was that using ultrapure water for the leachate test resulted in low metal solubility, indicating slight metal desorption in real environmental samples. Furthermore, maize stalk bio-adsorbent was used to minimize metal ion content in WWTP leachate samples produced by the storage of SS in terms of metal ion adsorption.

Disruption of exploratory behavior and olfactory memory in cockroaches exposed to sublethal doses of the neonicotinoid Thiamethoxam

Neonicotinoid insecticides (NNI) are agonists of insect nicotinic acetylcholine receptors (nAChR) that induce non-elucidate mechanisms of abnormal behavior in insects. In this work, we investigated the effects of sublethal doses of the neonicotinoid thiamethoxam (TMX) on neurochemical and physiological parameters in cockroaches. Sublethal doses of TMX (0.01–10 ng.g−1 body mass) caused significant alterations in most of the neurophysiological parameters evaluated. TMX reduced sustained locomotor activity by 19.9–25.8 %, depending on the dose. Leg grooming activity increased by 124.5 ± 3.4 %, 158.7 ± 3.5 %, 168.3 ± 3.4 %, and 160.4 ± 3.4 % (mean ± SEM) with TMX doses of 0.01, 0.1, 1, and 10 ng.g−1, respectively. Exploratory activity was significantly reduced only at the lowest TMX dose (0.01 ng.g−1) – the time spent immobile increased from 30 % to ∼45 %, whereas none of the doses affected the walking speed. Treatment with TMX (0.01 ng.g−1) markedly reduced the olfactory sensitivity of the cockroaches and also reduced the mechanosensory action potential amplitude, rise time and decay time by 61.2 ± 19 %, 50 ± 4 %, and 76.8 ± 9.5 %, respectively. In semi-isolated heart preparations, TMX caused positive chronotropism (increases of 34.7 ± 15.9 %, 26.8 ± 7.8 %, 43.0 ± 16.5 %, and 19.0 ± 13.7 % for 0.01, 0.1, 1, and 10 ng of TMX, respectively). TMX attenuated the activity of glutathione-S-transferase by 35.1 ± 6.4 % at the highest dose tested (10 ng.g−1). TMX caused alterations in the metal ion content of cockroach brains that varied with the dose tested and the ion examined. These findings indicate that sublethal doses of TMX can interfere with normal neurological function in cockroaches and disrupt brain metal ion homeostasis.

Synergistic removal of malachite green and Cr(Ⅵ) using ethylenediamine disuccinic acid functionalized silica gel

As common industrial raw materials, malachite green (MG) and Cr(Ⅵ) generally coexist in waste liquids discharged from the paper printing, leather, and textile industries, causing serious harm to humans and the environment. Therefore, developing an effective method for the synergistic removal of MG and Cr(Ⅵ) from aquatic environments is of great research value. In this work, the non-homogeneous Fenton-like catalysts, namely, EDDS-Silica and EDDS-Co2+-Silica were successfully prepared using ethylenediamine disuccinic acid (EDDS) and silica gel (Silica) as raw materials, and a non-homogeneous Fenton-like catalytic method was developed for the efficient and synergistic removal of MG and Cr(Ⅵ) from wastewater. EDDS-Silica and EDDS-Co2+-Silica were analyzed using Fourier infrared spectroscopy and X-ray photoelectron spectroscopy to determine their structural composition and elemental contents. The catalytic degradation and removal effects of these materials in an MG single-waste system were also investigated. The results demonstrated that the incorporation of both materials can overcome the limitation of the conventional Fenton reaction, which is its applicability to acidic environments only. Moreover, EDDS-Co2+-Silica showed better degradation effects on MG than EDDS-Silica. Quantitative calculations based on density functional theory were used to predict the optimal coordination forms between Co2+and EDDS-Silica as well as the MG structure. The lowest unoccupied and highest occupied molecular orbitals of the catalysts were then used to predict the active sites on which MG tends to capture or release electrons during the degradation reaction. The optimal conditions for the synergistic removal of MG and Cr(Ⅵ) from a binary system using EDDS-Co2+-Silica were further investigated under different influencing factors. The results showed that EDDS-Co2+-Silica still had excellent catalytic effect on the degradation rate of MG in the range of pH 3-7, and the optimal conditions were as follows: solution pH, 7; degradation time, 1 h; temperature, 25 ℃; H2O2 concentration, 20 mmol/L; and the initial mass concentration of Cr(Ⅵ), 25 mg/L. Under the above conditions, the degradation rate was increased from 87.25% to 96.67% compared with that in the MG monosystem. Obvious enhancements in degradation effect and efficiency confirmed that the incorporation of EDDS-Co2+-Silica was favorable for the synergistic removal of MG and Cr(Ⅵ) in the binary system. Strongly oxidizing Cr(Ⅵ) can participate in the Fenton reaction, thus promoting MG degradation over a wide pH range. Thus, a positive synergistic effect exists between MG and Cr(Ⅵ). Considering that a large number of metal ions remained in the solution after the degradation reaction, EDDS-Silica was added to the degradation solution, and adsorption experiments were performed for 4 h at 30 ℃to adsorb and remove Cr and Fe via the strong chelating property of EDDS. The total residual mass concentrations of Cr and Fe were 4.96 and 1.02 mg/L, respectively, which meet national emission standards. These findings indicate that EDDS-Silica has good effects on the removal of residual metal ions after the nonhomogeneous Fenton reaction. As heterogeneous Fenton-like catalysts, the aminopolycarboxylic acid-modified materials proposed in this study can simultaneously promote the Fenton reaction and remove residual metal ions, thereby effectively removing MG and Cr(Ⅵ) from the binary system while ensuring that the content of residual metal ions in the system meets environmental emission standards. This study has broad application prospects in dye degradation and heavy-metal-ion wastewater treatment, and provides a reference value and theoretical basis for the development of other similar ligand-modified materials.

The effect of inoculum source of different pollution levels on the performances of microbial fuel cell biosensors

Selection of inoculum sources is a key factor in constructing microbial fuel cells (MFCs), and the property of inoculum sources is greatly affected by the degree of environmental pollution. However, limited attention has been paid to how these differences affect the response of MFC biosensors. Here the effects of inoculum sources with varying pollution levels on the performances of constructed MFCs were evaluated, and the microbial communities were analyzed before and after inoculation. The results showed significant differences in the detection of biochemical oxygen demand (BOD) and toxicity (Cu2+) among the five groups of MFC biosensors. Combined with the data of the microbial community, the results indicated that the increase rate of the initial start-up voltage is related to the abundance of original electroactive bacteria (EAB) in the inoculum source. The higher the abundance of EAB, the faster increase rate in the initial start-up voltage and the shorter start-up time. The difference in the detection range of the BOD should be related to the ability of the microbial communities to withstand the organic shock loads. The microbial community's tolerance to Cu2+ was affected by the original water quality of the inoculum source. The high metal ion content leads to low sensitivity of MFC biosensor to Cu2+ ion. Enterobacteriaceae were abundant in all the five groups of MFCs, indicating that the dominant bacteria can be enriched in MFC anode biofilms with the inoculum sources of different pollution levels. The microbial community compositions of the anode biofilms were affected by the inoculum sources of different pollution levels, which in turn resulted in the differences in MFCs performances.

Revealing the effect regularity of cations on electron storage capacity of poly(heptazine imide) in “dark photocatalysis”

As a crystalline carbon nitride material, poly(heptazine imide) (abbreviated as PHI) exhibits higher photoinduced charge separation performance than traditional melon-based carbon nitride. The excellent charge separation is mainly attributed to the fact that the photoinduced electrons can be captured by cations (such as K+ and H+) and further stored in the PHI framework with the presence of sacrificial agents (such as methanol). Due to this special property, the stored electrons can be used for delayed H2O2 or H2 production in the “dark photocatalysis” field. Nevertheless, the effect regularity of cations on the electron storage capacity of PHI is still not clear. In this work, this problem has been preliminarily revealed. The electron storage capacity of a series of PHI materials has been quantified by the H2O2 production test in dark conditions. The result indicates that the electron storage capacity of PHI samples shows a volcano curve with the alkali metal ion content. Based on experimental tests and theoretical simulations, it is concluded that the electron storage capacity of PHI is related to the conductivity of the cation and its binding force for photogenerated electrons.

Facile Synthesis of Functionalized TEOS–Acylpyrazolone Hybrid for Removal of Targeted Heavy Metal Ions: An Experimental and DFT Study

AbstractThis study broadens the application of 4‐acylpyrazolone, a leading β‐diketone chelating ligand, to include the removal of heavy metal ions in our current work. As organic–inorganic hybrids have gained considerable attention these days due to their widespread applications in the field of Chemistry, we have employed a Schiff base reaction to generate 4‐acetyl‐5‐methyl‐2‐phenyl‐2,4‐dihydro‐pyrazole‐3‐one incorporated polysiloxane material using a cost‐effective one‐pot synthesis. Optimization studies were performed to eliminate Pb(II), Cu(II), and Cr(VI) by varying the beginning metal ion content, the required amount of the adsorbent, pH, required time, and temperature. The considerable opportunity for monolayered chemisorption is illustrated by the observation that adsorption opts for the Langmuir adsorption isotherm, with R2 values of 0.99. It employs an endothermic adsorption mechanism in a study at multiple temperatures and follows a pseudo‐second‐order kinetic model. FMO and MESP investigations of complexes formed through adsorption were successfully carried out through DFT. Material reveals quick recycling up to three alternating rounds with removal efficiencies of 82%, 56%, and 47% for Pb(II), Cu(II), and Cr(VI), respectively. Therefore, it may further be used for extraction of heavy metals from industrial effluents and provides the basis for future scope of this type of organic–inorganic hybrids in water treatment.

СНИЖЕНИЕ ЖЁСТКОСТИ ОРОСИТЕЛЬНОЙ ВОДЫ ОЗОНИРОВАНИЕМ

Abstract. The article presents the research on the effect of ozone treatment on the hardness of irrigation water. The effect of hard water on plant growth and development has been analyzed. It has been revealed that excessive magnesium and calcium ions in irrigation water lead to the suppression of agricultural crops and a decrease in their yield. To conduct laboratory studies, water was taken from a natural reservoir located near the village of Gvazda, Buturlinovsky District, Voronezh Region, which is used by local farmers to irrigate agricultural land. The sample was divided into two parts, one of which was subjected to ozone treatment, and the second was a control variant. Laboratory studies have established that the total water hardness in the natural reservoir was 21 dH, which corresponds to 7.5 mg eq / l. This level of hardness is excessive and will negatively affect plants. Ozonation at an average ozone concentration in the ozone-air mixture of 4.67 mg/m3 allowed to reduce the total water hardness to 14 dH, which is comparable to 5 mg eq/l. Intensive water softening occurred at ozone treatment doses of up to 840 mg min/m3. Consequently, ozonation reduces the content of polyvalent metal ions, which in high concentrations have a negative effect on plants. Modern compact, energy-efficient, high-performance ozonizers can be easily integrated into the design of sprinkler machines. Softer water will have a positive effect on the efficiency of irrigation and the reliability of irrigation systems. In addition, ozone water treatment will have a bactericidal and disinfectant effect, which will prevent the development of various diseases and pests.

Mn-Ce solid solution growth on Mn2O3 surface to form heterostructure catalysts with multiple active sites for toluene degradation

A solid solution-heterostructure catalyst with abundant active sites was successfully constructed in this study by in situ growth of Mn-Ce solid solution on the surface of Mn2O3. The solid solution structures with optimum physical and chemical properties were synthesized initially by controlling the Mn-Ce ratios. Subsequently, the reaction time was controlled to realize the orderly growth of the solid solution on the Mn2O3 surface. The catalyst (M−CeMn0.5) with solid solution-heterostructure formed by the reaction of Ce3Mn1 and Mn2O3 for 0.5 h could reach more than 90 % toluene degradation rate at 183 °C and was operated continuously for 15 h without deactivation. XRD showed that the appropriate reaction time resulted in the active components on the catalyst surface exhibiting lower crystallinity and reduced grain size. The reduction capacity (2.28 → 10.47 mmol/g) and the mobility of lattice oxygen were significantly enhanced in the M−CeMn0.5 catalyst compared to the Mn-Ce solid solution. Meanwhile, a high content of low valent metal ions (Ce3+/Ce4+ 0.33, Mn3+/Mn4+ 1.64) and reactive oxygen species (Oads/Olatt 0.53) were also present on the catalyst surface. The DFT demonstrated that the Mn atoms and Mn-O bridge sites on the solid solution surface exhibited high adsorption energy values for toluene (−0.8402/-0.8406 eV) and oxygen (−1.6546/-1.661 eV) molecules. The TEM indicated that lattice distortion and oxygen vacancies were formed at the interface between the solid solution and Mn2O3 at the interface. The synergy of multiple active sites favors the generation of reactive oxygen species and thus promotes p-methyl dehydrogenation. Meanwhile, the high mobility of lattice oxygen facilitates the breakage of benzene ring. This study provides a new strategy for the synthesis of efficient Mn-Ce-based catalysts.

Experimental study on freezing temperature and its influencing factors of loess contaminated by heavy metals

This paper attempts to reveal the freezing temperature and its influencing factors of heavy metal-contaminated loess by adopting two cooling methods: fast and slow grading. As a result, Lanzhou loess was used as an experimental material to make polluted soil with varying heavy metal concentrations and initial water content. The pollutant elements included Zn, Ni, Cu, Cr, Cd, and Pb. The findings demonstrate that: 1) The slow cooling rate causes supercooling, jumping, and a progressive decrease in the temperature of the polluted soil. Different cooling methods have no obvious effect on freezing temperature. Furthermore, the freezing temperature of contaminated soil varies depending on its water content. The impact of increasing water content on freezing temperature is not evident; 2) The freezing temperature of loess decreases with the increase of heavy metal ion content. The freezing temperature of loess polluted by Zn, Ni and Cd ions decreased linearly with the increase of ion content. The influence of cations on the freezing temperature of loess is as follows: Zn2+> Ni2+> Cd2+> Cr3+> Pb2+> Cu2+. The influence order of anions is Cl− > SO42−; 3) The freezing temperature of loess containing heavy metal ions is about equal to the freezing temperature of the corresponding heavy metal solution plus the freezing temperature of loess itself. The freezing temperature of heavy metal-polluted loess follows the temperature superposition principle.

Pollutant degradation and hydrogen production of landfill leachate membrane concentrates via aqueous phase reforming

Membrane filtration is a mainstream method for landfill leachate treatment, leaving the landfill leachate membrane concentrates (LLMCs) a high-toxicity residue. Conventional LLMCs disposal technology shows specific challenges due to the low biodegradability, high inorganic salts, and high heavy metal ions content of LLMCs. Therefore, it is necessary to degrade LLMCs with a more suitable technology. In this study, a special method was proposed to convert some organic chemicals into valuable compounds by aqueous phase reforming (APR). Ni-based catalysts (Ni//La2O3, Ni/CeO2, Ni/MgO, and Ni/Al2O3) were prepared to investigate the effect of different supports on the APR of LLMCs. APR performed outstanding characteristics in the decrease of chemical oxygen demand (COD) and total organic carbon (TOC), the degradation of macromolecules, and the removal of heavy metal ions in the aqueous phase. In addition, H2 was generated which is beneficial for energy compensating during the APR process. The best-performing catalyst (Ni/Al2O3) was selected to investigate the effects of reaction temperature, reaction time, and catalyst addition on product distribution. The optimal H2 selectivity (44.71%) and H2 production (11.63 mmol/g COD) were obtained at 250 °C with 2 g Ni/Al2O3 usage for 1 h. This paper provided a new perspective on the disposal of LLMCs, which will degrade pollutants efficiently.

Characteristics of Cellulose Acetate Composite Membranes (Ca/Cs, Ca/Pva, Ca/Peg) As Cu(Ii) Metal Ion Filtration Membranes

Industrial development in Indonesia has caused increased pollution, including water pollution by heavy metals, one of which is the metal ion Cu(II). Cellulose acetate composite membranes have been widely used to overcome the problem of Cu(II) metal ion content in water, however, studies on the performance of cellulose acetate membranes with various types of chitosan, polyvinyl alcohol (PVA) and polyethylene glycol (PEG) composites have not been widely reported. This research aims to analyze the characteristics of cellulose acetate composite membranes with chitosan, PEG, and PVA using FTIR and SEM and to determine the performance of these cellulose acetate composite membranes in filtering Cu(II) metal from the resulting rejection values. The membrane was made using the phase inversion method and the composite membrane was made using the dip-coating method. The results of characterization using FTIR showed that there were no new peaks in all cellulose acetate composites, so there were only physical interactions in the composites. SEM analysis shows that the surface of the composite membrane is more irregular and the porosity increases. The performance of the composite membrane in filtering Cu(II) metal is better than the pure cellulose acetate membrane.

Recovery of Metals from the "Black Mass" of Waste Portable Li-Ion Batteries with Choline Chloride-Based Deep Eutectic Solvents and Bi-Functional Ionic Liquids by Solvent Extraction.

Lithium-ion portable batteries (LiPBs) contain valuable elements such as cobalt (Co), nickel (Ni), copper (Cu), lithium (Li) and manganese (Mn), which can be recovered through solid-liquid extraction using choline chloride-based Deep Eutectic Solvents (DESs) and bi-functional ionic liquids (ILs). This study was carried out to investigate the extraction of metals from solid powder, black mass (BM), obtained from LiPBs, with various solvents used: six choline chloride-based DESs in combination with organic acids: lactic acid (1:2, DES 1), malonic acid (1:1, DES 2), succinic acid (1:1, DES 3), glutaric acid (1:1, DES 4) and citric acid (1:1, DES 5 and 2:1, DES 6). Various additives, such as didecyldimethylammonium chloride (DDACl) surfactant, hydrogen peroxide (H2O2), trichloroisocyanuric acid (TCCA), sodium dichloroisocyanurate (NaDCC), pentapotassium bis(peroxymonosulphate) bis(sulphate) (PHM), (glycine + H2O2) or (glutaric acid + H2O2) were used. The best efficiency of metal extraction was obtained with the mixture of {DES 2 + 15 g of glycine + H2O2} in two-stage extraction at pH = 3, T = 333 K, 2 h. In order to obtain better extraction efficiency towards Co, Ni, Li and Mn (100%) and for Cu (75%), the addition of glycine was used. The obtained extraction results using choline chloride-based DESs were compared with those obtained with three bi-functional ILs: didecyldimethylammonium bis(2,4,4-trimethylpentyl) phosphinate, [N10,10,1,1][Cyanex272], didecyldimethylammonium bis(2-ethylhexyl) phosphate, [N10,10,1,1][D2EHPA], and trihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl) phosphinate, [P6,6,6,14][Cyanex272]/toluene. The results of the extraction of all metal ions with these bi-functional ILs were only at the level of 35-50 wt%. The content of metal ions in aqueous and stripped organic solutions was determined by ICP-OES. In this work, we propose an alternative and highly efficient concept for the extraction of valuable metals from BM of LiPBs using DESs and ILs at low temperatures instead of acid leaching at high temperatures.

High Concentrations of Se Inhibited the Growth of Rice Seedlings.

Selenium (Se) is crucial for both plants and humans, with plants acting as the main source for human Se intake. In plants, moderate Se enhances growth and increases stress resistance, whereas excessive Se leads to toxicity. The physiological mechanisms by which Se influences rice seedlings' growth are poorly understood and require additional research. In order to study the effects of selenium stress on rice seedlings, plant phenotype analysis, root scanning, metal ion content determination, physiological response index determination, hormone level determination, quantitative PCR (qPCR), and other methods were used. Our findings indicated that sodium selenite had dual effects on rice seedling growth under hydroponic conditions. At low concentrations, Se treatment promotes rice seedling growth by enhancing biomass, root length, and antioxidant capacity. Conversely, high concentrations of sodium selenite impair and damage rice, as evidenced by leaf yellowing, reduced chlorophyll content, decreased biomass, and stunted growth. Elevated Se levels also significantly affect antioxidase activities and the levels of proline, malondialdehyde, metal ions, and various phytohormones and selenium metabolism, ion transport, and antioxidant genes in rice. The adverse effects of high Se concentrations may directly disrupt protein synthesis or indirectly induce oxidative stress by altering the absorption and synthesis of other compounds. This study aims to elucidate the physiological responses of rice to Se toxicity stress and lay the groundwork for the development of Se-enriched rice varieties.

Mutual-benefit modification of the coagulant solution and fly ash for enhanced sludge dewatering

Faced with the escalating volume of municipal sludge from wastewater treatment plants, urgent measures are required to enhance the sludge dewatering efficiency. This study introduces an innovative and cost-effective approach for mutual modifications of AlCl3 coagulant solution (AC) and fly ash (FA) powder as additives to significantly enhance sludge dewaterability. Unlike the traditional method that modifies agents alone, our technique achieves dual functionalities via blending FA with AC at room temperature. The modified FA (MFA) exhibits a 60 % increase in specific surface area to 2.176 m2/g and ζ-potential shift from –22.2 to +2.0 mV, meanwhile enhances the metal ions content in the modified AC (MAC) by dissolving 96.5 % of Ca, 70.3 % of Mg, 10.6 % of Fe, and 6.1 % of Al ions from FA. When sludge is treated with 5 % MAC and 10 % MFA, the water content in the filter cake is reduced from 84.9 % originally to 52.9 % through plate-frame pressure filtration (PFPF), a significant improvement over 65.4 % for that with unmodified AC and FA treatment, corresponding to the decreased specific resistance to filtration (SRF) and increased the filtration flux during the draining phase. The notable dewaterability enhancement through AC and FA modification is due to the enhanced flocculation and charge neutralization by the abundant metal ions in MAC, coupled with the MFA-facilitated water adsorption and drainage channel maintenance. This one-step, double-benefit modification not only surpasses traditional methods in dewatering efficiency but also reduces sludge treatment costs by 42.4 %, offering a sustainable solution to the increasing challenges of municipal sludge management.

Efficient synthesis of high vinyl polybutadiene based on continuous flow microchannel reactor

AbstractThe traditional batch synthesis of liquid rubber faces issues such as low monomer polymerization concentration, poor uniformity of the reaction system, and inadequate heat dissipation, resulting in an unsatisfactory synthesis efficiency. This study presents a method for the rapid and efficient synthesis of high vinyl 1,2‐polybutadiene liquid rubber using butadiene as the monomer and n‐butyllithium as the initiator. By applying continuous flow microchannel reactors, the limitation of traditional synthesis method can be overcome. The addition of a modifier in the raw material promotes the formation of high vinyl structure. The preparation of liquid rubber requires the addition of a large amount of metal lithium initiator. However, for aerospace sealants, there is a requirement for low metal ion content. To address this, we employed different methods to reduce the metal ion content in the liquid rubber and increase its purity. Ultimately, we achieved the synthesis of high‐purity polybutadiene liquid rubber with 1,2‐vinyl content exceeding 88%, narrow molecular weight distribution, and tunable molecular weights. This research will provide technical guidance for the industrial application of polybutadiene synthesis in continuous flow microchannel reactors.

Topological understanding of the influence of mixed alkali components on the structure and properties of aluminosilicate glass

Herein, aluminosilicate (AS) glasses exhibit varying trends in Vickers hardness (HV), coefficient of thermal expansion, softening temperature (Ts) and glass transition temperature owing to the mixed alkali effect. To elucidate the mechanism of the mixed alkali effect, the glass structure was characterised using multiple methods. Employing temperature-dependent topological constraint theory, the variations in HV and Ts were investigated, and the constraint strengths of sodium (Na) and lithium (Li) in AS glasses were calculated. The findings indicated that an increase in alkali metal–ion content elevates the proportion of non-bridging oxygen, leading to a progressive decrease in constraint strength and the depolymerisation of the glass structure. For AS glasses with mixed alkali components, as the content of Li2O replacing Na2O increases, the constraint strength of the glass structure below the critical temperature (Tc) gradually rises, while above Tc, it undergoes unconventional changes. These alterations lead to non-linear variations in glass properties.

Storability and Brewing Quality of Corn Grits: Impacts of Storage Temperature, Particle Size and Key Compositional Factors

Across international brewing operations corn grits from different suppliers vary substantially in terms of their physical properties and chemical composition. Present research aimed to highlight the key factors determining the brewing quality of stored corn grits. Six grits samples were sourced with different particle sizes (that ranged from 0% to 74% of particles ≤0.355 mm) and stored at 10 °C, 20 °C, or 30 °C for 0, 2, 4, 8, 12, and 16 months. Samples were analysed for moisture, extract, lipid, trihydroxy fatty acids (THFA) and pro-oxidant metal ion contents. Particle size range was measured using sieve analysis. Increasing levels of THFA occurred on storage due to lipid oxidation and are negative indicators of brewing quality. PLS-R modelling of THFA levels (R 2 = 0.83) revealed particle size (hence surface area for oxidation) was the most important factor (∼60% of the total R 2) followed by storage time (∼25%) and temperature (∼7%). Metal ion content and lipid content of grits were minor contributors. Results showed that coarser milling of grits offers protection against lipid oxidation even after 8 months at 30 °C. These insights into key factors determining the rate of lipid oxidation in stored corn grits will help to develop better supply chain management and storage practices with which to assure their brewing quality.