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Perovskite type hydrides have emerged as a focal point in hydrogen storage applications as potential candidates in recent years. However, the currently synthesized perovskite hydrogen storage materials suffer from high hydrogen desorption temperatures and unstable reactions. To identify promising perovskite hydrogen storage materials, this study explores the hydrogen storage properties of XCrH 3 (X = Na, K) and KYH 3 (Y Mo, W) based on first-principles (FPs) calculations. The results indicate that NaCrH 3 and KCrH 3 exhibit half-metallic properties, while KMoH 3 and KWH 3 are metallic materials with high hydrogen storage safety. Mechanical property analysis reveals that NaCrH 3 exhibits the highest hardness, indicating better stability for hydrogen storage. Thermodynamic analysis shows that KCrH 3 has a lower hydrogen desorption temperature than the other three compounds, with NaCrH 3 having the second-lowest. The gravimetric hydrogen storage capacities of NaCrH 3 , KCrH 3 , KMoH 3 , and KWH 3 are 3.85 wt%, 3.21 wt%, 2.19 wt%, and 1.34 wt%, respectively. Overall, NaCrH 3 demonstrates superior gravimetric hydrogen storage capacity, stability, and safety, making it a promising candidate for new perovskite type hydrogen storage materials. • All four compounds are magnetic materials and stable. • NaCrH 3 exhibits the highest hardness with superior stability in hydrogen storage and release reactions. • NaCrH 3 has a higher gravimetric hydrogen storage capacity and a lower evolution temperature. • KWH 3 is a ductile material, and the other three are brittle materials. [ABSTRACT FROM AUTHOR]

MgB 2 has a wide range of applications as a crucial superconducting material in fields such as electronics and communications, but its weak mechanical properties limit its use in extreme environments such as high pressure. Therefore, this article explores the enhancement mechanism of the mechanical properties for MgB 2 by substituting Mg sites with Nb element based on first principles. After substitution, NbB 2 has better thermodynamic stability, and the introduction of Nb-d state enhances light absorption. In terms of mechanics, due to the higher electron accumulation density in the Nb–B bond and a shorter bond length (2.451 Å), the atomic interactions become tighter and stronger. As a result, both elastic constants and modulus are enhanced, exhibiting high stiffness, high compression resistance, etc. The spatial distribution of 3D elastic anisotropy is closer to a spherical shape and the universal anisotropy index (A U ) tends to approach 0, which indicates the mechanical properties in all directions are more consistent, making it easier to predict and control. Meanwhile, the elastic modulus rises smoothly with increasing hydrostatic pressure and is not affected by lattice compression at low hydrostatic pressure. The change rate of B–B bond length is 6.8 % at 100 GPa, which becomes the main reason for the enhancement of mechanical properties. The article provides a theoretical foundation for the preparation of superconductors with excellent mechanical properties under extreme conditions. [ABSTRACT FROM AUTHOR]

Root border cells (RBCs) and their mucilage are considered to play an important role in protecting root tip from aluminum (Al) toxicity, but their interactions with silicon (Si) under Al stress still remain unclear. Here, we investigated the effect of Si on the formation of RBCs under Al stress and the related detoxification mechanism in hydroponically grown rice (Oryza sativa L.). The results showed that Si could prevent the separation of RBCs from each other by increasing the degree of pectin methylesterification in root tip cell wall, thereby keeping more RBCs around the root tip. Also, Si maintained the viability of RBCs, increased the amount of mucilage, and reduced the content of total Al and free Al in root tips. Moreover, the RBCs accumulated more Al and Si simultaneously than root tip in the Al treatments with Si supply. Overall, these results indicated that Si reduced the toxicity of Al to RBCs through formation of Si–Al complex on the RBCs, thereby improving the viability of RBCs and promoting the secretion of mucilage. Concomitantly, Si, RBCs and their mucilage could form a protective sheath at the root tip, which prevented Al from diffusing into the root tip, thereby alleviating Al toxicity in rice root tips. [Display omitted] • Si kept more RBCs around the root tip under Al stress. • Si improved the viability of RBCs and promoted the production of mucilage. • The formation of Si–Al complex on the RBCs reduced the toxicity of Al to root tip. • A protective sheath formed by RBCs and mucilage prevented Al from entering root tip. [ABSTRACT FROM AUTHOR]

The layered structure of GeS exhibits commendable thermal stability and holds significant promise in the realms of optoelectronics and ion batteries. But its application is limited as dilute magnetic semiconductor. Therefore, this study delves into the impact of 3d transition metal (TM = V, Cr, and Mn) doping on the magnetic and optical characteristics of two-dimensional GeS monolayer through a first-principles calculation method grounded in density functional theory. The findings elucidate that all doping systems lead to a reduction in the band gap, with the V-doped system exhibiting the most significant diminishment. After doping process, magnetic coupling emerges between the electrons in the TM-3d state and those in the S-3p state, resulting in the manifestation of magnetic semiconductor characterized by magnetic moments of 3 μ B , 4 μ B , and 5 μ B , respectively. Comparative analysis with the pristine GeS monolayer, it reveals enhancements in optical absorptivity and refractive index within both the infrared and visible spectra of the doped systems. Notably, the V-doped system showcases superior optical properties due to its narrower band gap, facilitating more efficient electron transitions to the conduction band. Consequently, TM (TM = V, Cr, and Mn)-doped GeS monolayer hold promising potential in the realms of spintronics and optoelectronics. [ABSTRACT FROM AUTHOR]

Anatase TiO 2 is widely used in solar photocatalysis. However, the optical properties are limited by its ability to capture visible light and its poor activity. In order to obtain ideal material properties, GGA + U method based on density functional theory is used to study the electronic structure and optical properties of anatase phase TiO 2 and its (112) surface and Cr and Co-doped TiO 2 (112) surface. The results show that the transition metal Cr-doped system is more stable than the Co-doped system. The four systems exhibit semiconducting properties. The indirect band gap value of intrinsic TiO 2 is 3.245 eV, and the impurity bands appear in the spin-up energy bands after Cr, Co doping. The impurity states of the doped system spin split, which transforms the non-magnetic semiconductor into a semiconductor with net magnetic moments of 2 μB and 3 μB, respectively. In addition, the Cr, Co-doped systems show excellent optical properties, and the absorption coefficients are red-shifted in the range of (0–3 eV) with higher optical absorptivities. Through the investigation, it is evident that doping results in different degree of band gap change. As the conduction band moves towards the lower energy level, an impurity band is generated near the Fermi level. The presence of the impurity band fundamentally alters the initial transition mode of the electron, making the transition require less energy, thus enabling enhanced optical properties. The doping system enhances the lepton threshold of electrons and light absorption by changing the mode of inter-band leaps and decreasing the reflectivity, making them candidates in the field of optoelectronics and photocatalysis. [ABSTRACT FROM AUTHOR]

Efficient photocatalytic water splitting is of holds paramount importance in addressing contemporary energy and environmental challenges. The emergence of symmetry-deficient Janus two-dimensional materials has opened new avenues for advancing the field of photocatalytic hydrogen production. Using first-principles calculations, we investigated a novel Janus Zn 2 XY (X = S, Se; Y Se, Te; X≠Y) monolayer. The results demonstrate exceptional structural stability and favorable characteristics for water splitting, including direct band gaps and optimal band edge alignment. Spatially separating band edge states and the intrinsic vertical electric field effectively suppress the recombination rate of photogenerated electron-hole pairs. Strain engineering enhances the monolayer's capacity for visible light absorption. Furthermore, All Janus monolayers exhibit an impressive electron mobility of 103 cm2/V/s, with Janus Zn 2 STe and Zn 2 SeTe monolayers reaching 16.28% and 16.34% Solar-to-hydrogen (STH) efficiencies, respectively. These findings showcase the superior performance of Janus Zn 2 XY in water splitting and guide future experimental endeavors. [Display omitted] • Janus Zn 2 XY (X = S, Se; Y Se, Te; X≠Y) shows promise for water splitting. • They exhibit suitable bandgaps and edge alignments for water splitting. • Exceptional stability and high electron mobility characterize these materials. • In-built electric fields effectively suppress electron-hole recombination. • Strain is an effective strategy to improve their light absorption. [ABSTRACT FROM AUTHOR]

A molecular dynamics simulation is performed to investigate the icosahedron in Mg 70 Zn 30 metallic glass during solidification at the cooling rate of 1 × 10 13  K/s. It is found that the 1551, 1541 and 1431 bond-types are closely related to 13-atom icosahedron-like clusters. Two kinds of clusters are very similar to full icosahedron in geometry. The three clusters can transform into each other by changing one bond between a pair of outer atoms. One distorted icosahedron act as the intermediate between the two others. This work provides an insight into the glass formation in alloy from the cluster-level structural viewpoint and will shed light on developing more metallic glasses. [ABSTRACT FROM AUTHOR]

The mechanism by which temperature sensitivity (TS) of soil N 2 O emissions is increased by agricultural management with application of nitrogen fertilizer (AMN) is unclear. We hypothesized that a higher TS of N 2 O emission induced by AMN is the result of the faster growth of specific microorganisms in response to faster nitrogen (N) mineralization at higher temperatures. To test this hypothesis, we used reciprocal transplants to separate the contributions of abiotic and microbial components to the TS of N 2 O emissions in an arable soil receiving organic and inorganic fertilizers and its neighboring natural grassland soil treated with two levels of N. N 2 O sources were separated with acetylene, and the abundances of N 2 O-producing microbes were assessed by quantifying the copy numbers of the associated functional genes. Compared with natural soil, only changes in abiotic properties increased the Q 10 (the factor by which the rate increases with a 10 °C rise in temperature) by 105.7%, while changes in both abiotic and the microbiome increased the Q 10 by 225.2%. Higher TS of N 2 O emission in the arable soil induced by a microbiome shift was associated with faster N mineralization, increased proportion of nitrification-N 2 O emission, and faster growth of ammonia-oxidizing bacteria at higher temperatures. Addition of ammonium nitrate further enhanced the TS of N 2 O emissions, the proportion of nitrification-N 2 O emission, and the increased extent of the growth of ammonia-oxidizing bacteria in the soil with AMN compared to the natural grassland soil. Substrate-driven growth of ammonia-oxidizing bacteria with higher substrate preference contributes significantly to the higher TS of N 2 O emission caused by AMN. [ABSTRACT FROM AUTHOR]

Silicon (Si), as a beneficial element for a number of crops, can significantly improve the growth and yield of crops partly through silicon-enhanced resistance to biotic and/or abiotic stress. However, the mechanisms of Si-improved growth and fruit quality of horticultural crops, in particular, remain poorly understood. In the present study, two-year field experiments were conducted aimed at testing the effects of different sources of silicate fertilizers applied on table grape yield, fruit quality and fruit commercial characteristics during storage period. For this, two table grape cultivars were tested with treatments including: (I) no silicate fertilizer (control), (II) steel slag fertilizer and (III) water-cooling slag fertilizer. The application rate of silicate fertilizer was 600 kg SiO 2 ha −1 . Fruit yield, cluster weight, berry weight, berry size ( i.e. length and width) were significantly increased by application of silicon fertilizers ( P < 0.05) in both cultivars. Table grape fruit yield was 13.5% higher in the treatment with either water-cooling slag fertilizer or steel-slag fertilizer than in the control across the two years tested. Silicon fertilization significantly improved fruit total soluble solids, the ratio of total soluble solids to titratable acidity (TSS/TA) and fruit firmness. Applying silicate fertilizer significantly extended the fruit shelf-life by decreasing fruit respiratory intensity, decay incidence and weight loss ( P < 0.05). Water-cooling slag fertilizer did not show a significant difference from steel slag fertilizer in grape yield and fruit quality. Our findings suggest that silicate fertilizer could prolong fruit shelf-life and increase the yield and quality of grape in a calcareous grey desert soil. [ABSTRACT FROM AUTHOR]

Nitrification inhibitors (NIs) have been used extensively to reduce nitrogen losses and increase crop nitrogen nutrition. However, information is still scant regarding the influence of NIs on nitrogen transformation, nitrous oxide (N2O) emission and nitrogen utilization in plastic-film-mulched calcareous soil under high frequency drip-fertigated condition. Therefore, a field trial was conducted to evaluate the effect of nitrapyrin (2-chloro-6-(trichloromethyl)-pyridine) on soil mineral nitrogen (N) transformation, N2O emission and nitrogen use efficiency (NUE) in a drip-fertigated cotton-growing calcareous field. Three treatments were established: control (no N fertilizer), urea (225 kg N ha-1) and urea+nitrapyrin (225 kg N ha-1+2.25 kg nitrapyrin ha-1). Compared with urea alone, urea plus nitrapyrin decreased the average N2O emission fluxes by 6.6–21.8% in June, July and August significantly in a drip-fertigation cycle. Urea application increased the seasonal cumulative N2O emission by 2.4 kg N ha-1 compared with control, and nitrapyrin addition significantly mitigated the seasonal N2O emission by 14.3% compared with urea only. During the main growing season, the average soil ammonium nitrogen (NH4+-N) concentration was 28.0% greater and soil nitrate nitrogen (NO3--N) concentration was 13.8% less in the urea+nitrapyrin treatment than in the urea treatment. Soil NO3--N and water-filled pore space (WFPS) were more closely correlated than soil NH4+-N with soil N2O fluxes under drip-fertigated condition (P<0.001). Compared with urea alone, urea plus nitrapyrin reduced the seasonal N2O emission factor (EF) by 32.4% while increasing nitrogen use efficiency by 10.7%. The results demonstrated that nitrapyrin addition significantly inhibited soil nitrification and maintained more NH4+-N in soil, mitigated N2O losses and improved nitrogen use efficiency in plastic-film-mulched calcareous soil under high frequency drip-fertigated condition. [ABSTRACT FROM AUTHOR]

Belowground biodiversity is essential for soil functioning, but the effect of belowground biodiversity loss on food safety is unknown. We investigated the loss of soil microbial diversity on insecticides accumulation in Brassica. We manipulated soil biodiversity using the dilution-to-extinction approach in a Brassica-soil-insecticide system, monitored microbial communities via high-throughput sequencing, and identified potential functional microbes. Compared with unsterilized soil, the richness of functional bacteria was reduced by 14.1%, 36.2%, 51.6% and 73.2%, respectively, in the corresponding sterilized soil inoculated with 1-, 10 −2 -, 10 −4 - and 10 −6 -fold diluted soil suspension. The acetamiprid and imidacloprid concentrations increased significantly in Brassica tissues grown in sterilized soil inoculated with 10 −6 -fold diluted suspension. A bacterial group predominated in functional microbes of soils inoculated with 1-, 10 −2 - or 10 −4 -fold diluted suspension, but the relative abundance declined in soil inoculated with a 10 −6 -fold diluted suspension. Our findings revealed that undesirable impacts by the loss of soil biodiversity at an intermediate level on the accumulation of soil contaminant in plants could be alleviated by microbial functional redundancy through disproportionally complementary growth of specific functional microbial taxa, but severe loss of soil biodiversity would threaten food safety. [ABSTRACT FROM AUTHOR]

Slag-based silicate fertilizer has been widely used to improve soil silicon- availability and crop productivity. A consecutive early rice-late rice rotation experiment was conducted to test the impacts of steel slag on soil pH, silicon availability, rice growth and metals-immobilization in paddy soil. Our results show that application of slag at a rate above higher or equal to 1 600 mg plant-available SiO2 per kg soil increased soil pH, dry weight of rice straw and grain, plant-available Si concentration and Si concentration in rice shoots compared with the control treatment. No significant accumulation of total cadmium (Cd) and lead (Pb) was noted in soil; rather, the exchangeable fraction of Cd significantly decreased. The cadmium concentrations in rice grains decreased significantly compared with the control treatment. In conclusion, application of steel slag reduced soil acidity, increased plant–availability of silicon, promoted rice growth and inhibited Cd transport to rice grain in the soil-plant system. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the impacts of organic-supplementation of a chemical fertilizer for improving soil biological activity, particularly towards disease suppression, in a drip-irrigated cotton system. Over a two-year field-based trial, our study characterized effects of partial substitution of chemical fertilizer with two types and amounts of organic components on the size, activity, carbon utilization potential, and culturable groups of pathogenic and antagonistic microbiota. The total microbial community size increased with application of chemical fertilizer ( P < 0.05), and more so when chemical fertilizer was supplemented with organic amendments ( P < 0.05). Alteration of microbial biomass carbon to nitrogen ratio, and the ratio of culturable bacteria and fungi, indicated that increases in the microbial community were underpinned by changes in bacteria. Enzymatic activity was greater in soils receiving fertilizer with organic supplement ( P < 0.05). Multivariate analysis indicated that there was no influence of fertilizer treatments on carbon utilization profiles (CUPs; P > 0.05), but a strong year-effect was evident ( P < 0.05). The population size of Verticillium dahliae and Fusarium oxysporum decreased with organic amendments ( P < 0.05), whilst antagonistic Trichoderma spp. and Bacillus spp. were inversely correlated to the pathogen populations. Overall, the results of this exploratory study support partial substitution of inorganic fertilizer with organic manure or bio-organic fertilizer to promote suppression of cotton root diseases. Associated benefits on soil biological quality will further increase the sustainability of this agroecosystem. [ABSTRACT FROM AUTHOR]

Using a trial and error method to measure amorphous forming ability in the experiment is a complex and time-consuming process. Therefore, it is necessary to devise a method that can rapidly and accurately predict the amorphous forming ability. In this study, two models, artificial neural network and convolutional neural network, are proposed for the prediction of amorphous forming ability of various amorphous alloys. The prediction accuracy of the two models reached 0.77623 and 0.71693, respectively, both of which were more than 19% higher than the reported prediction accuracy of the 13 criteria. This result shows that artificial neural network and convolutional neural network models can accurately predict the amorphous forming ability of a variety of amorphous alloys and provide theoretical guidance for the development and preparation of amorphous alloys. [ABSTRACT FROM AUTHOR]

The foliar uptake and transport of formaldehyde into Bracket plants from air via leaves and roots to external water was investigated in an air–plant–water system. The results indicated that formaldehyde could be quickly taken up by plant tissues, and that formaldehyde accumulated in leaves could be released rapidly back into air when the formaldehyde level in air was diminished. This rapid reversible translocation of formaldehyde between plant leaves and air resulted in high formaldehyde concentrations in leaf dews, depending upon exposure levels of formaldehyde in air. Meanwhile, formaldehyde could be transported from air to plant rhizosphere solution through downward transport. The concentration of formaldehyde in rhizosphere solutions increased with exposure time and the formaldehyde level in air. The efficiency of the leaf extracts to break down formaldehyde increased, probably because of an increase in oxidative potential of the leaf extracts. Taken together, the main mechanism of formaldehyde loss in air can be attributed to the accumulation by (or breakdown in) plant tissues; the removal rate of formaldehyde from air reached 135 μg h −1 plant −1 in the experimental condition. [ABSTRACT FROM AUTHOR]

Highlights: [•] Both TCE and TCB could be transported from air to the plant rhizosphere solution rapidly through foliar uptake and downward transport pathways. [•] The downward transport efficiency of the TCE and TCB followed the order of wheat>tomato>corn. The transport efficiency of TCE was far greater than that of TCB. [•] TCE concentrations observed in corn rhizosphere solutions were lower in the TCE and TCB mixture system than in single contaminant systems. [•] The downward transport of TCE was inhibited, while that of TCB was enhanced in the mixed contaminant system. [Copyright &y& Elsevier]

Abstract: Disposal of heavy metal contaminated biomass after phytoremediation is still unfeasible. This paper presents a viable phyto-extraction approach in which metals in contaminated soils are stabilized by nursery stocks before transplantation for greening. In this respect, two pot-experiments are reported comparing seven nursery stocks species exposed to different Cd levels. The first experiment revealed that Cd was mainly stabilized in the roots of all species studied. Greater amounts of Cd were accumulated in the epidermis than cortex plus stele. Cupressus Blue Ice showed greatest tolerance to the 100 and 200mgkg−1 Cd stresses. The second experiment additionally evaluated the possible risk of Cd release after transplanting the Cd treated plants into uncontaminated soil. After 120 days of transplantation, the relatively trace amounts of Cd in the roots of Euonymus japonicus, Pittosporum tobira and C. Blue Ice had either been partially transferred into the shoots or released into the soil. The highest Cd concentration increase in bulk soil (0.428mgkg−1), however, was much lower than the environmental quality standard for soils of China (1mgkg−1). The potential effectiveness of this technique in the use of Cd-contaminated soil and further investigation needed in the field trials were also evaluated. [Copyright &y& Elsevier]

Summary: Salicylic acid (SA) may accelerate the cell death of cadmium-stressed roots to avoid cadmium (Cd) uptake by plants or may play positive roles in protecting the stressed roots from Cd-induced damage. To test these hypotheses, we performed a series of split-root hydroponic experiments with one-half of rice (Oryza sativa L. cv. Jiahua 1) roots exposed to 50μM Cd and the other half not exposed. The objectives were to elucidate the effects of SA pretreatment on the time-dependent changes of H2O2 levels in roots, antioxidant defense system in different organs, root cell death and the dynamic distribution of Cd in the plants. In the split-root system, a higher Cd uptake rate was observed in the Cd-stressed portions of roots compared with the treatment with the whole roots exposed to Cd. Furthermore, an appreciable amount of Cd was translocated from the Cd-exposed roots to the unexposed roots and trace amounts of Cd were released into the external solution. The split-root method also caused the two root portions to respond differently to Cd stress. The activities of major antioxidant enzymes (superoxide dismutase, SOD; peroxidase, POD; and catalase, CAT) were significantly suppressed in the Cd-treated roots, hence leading to H2O2 burst, lipid peroxidation, cell death and growth inhibition. By contrast, in the non-Cd-treated roots, the activities of enzymes (SOD, CAT, and POD) and root growth were persistently stimulated during the experimental period. The H2O2 accumulation and lipid peroxidation were also induced in the non-Cd-treated roots, but they were significantly lower than those of the Cd-treated roots. The concentrations of glutathione (GSH) and non-protein thiols (NPT) in the Cd-treated roots were significantly higher than those of the untreated roots. SA pretreatment elevated enzymatic and non-enzymatic antioxidants, and the concentrations of GSH and NPT in roots and shoots, hence leading to alleviation of the oxidative damage as indicated by the lowered H2O2 and MDA levels. Furthermore, SA pretreatment mitigated the Cd-induced growth inhibition in both roots and shoots and increased transpiration compared with non-SA-pretreatment under Cd exposure. It is concluded that Cd can be partly transferred from the Cd-exposed roots to Cd-unexposed roots and that cell death can be accelerated in the Cd-stressed roots in response to Cd stress. The SA-enhanced Cd tolerance in rice can be attributed to SA-elevated enzymatic and non-enzymatic antioxidants and NPT, and to SA-regulated Cd uptake, transport and distribution in plant organs. [Copyright &y& Elsevier]

Abstract: The main objective of this study was to elucidate the roles of silicon (Si) in enhancing tolerance to freezing stress (−5°C) in two contrasting wheat (Triticum aestivum L.) cultivars: i.e. cv. Yangmai No. 5, a freezing-susceptible cultivar and cv. Linmai No. 2, a freezing-tolerant cultivar. Shoot dry weight of the freezing-susceptible wheat was significantly lower under freezing stress than in controls, but increased significantly with Si amendment. The freezing treatment did not affect shoot dry weight of the freezing-tolerant cultivar. The leaf water content was considerably decreased by freezing stress in the freezing-susceptible cultivar, but was significantly increased by Si amendment. In contrast, freezing treatment did not significantly reduce leaf water content in the freezing-tolerant cultivar and Si played no role in water retention in this cultivar. The concentrations of H2O2 and free proline along with malondialdehyde (MDA) were progressively enhanced by freezing stress in the two wheat cultivars used, but were significantly suppressed by amendment with Si. The major antioxidant enzyme activities and non-enzymatic antioxidants (i.e. glutathione and ascorbic acid) in the leaves of freezing-stressed plants were decreased, but were stimulated significantly by the exogenous Si. The possible mechanisms for Si-enhanced freezing stress may be attributed to the higher antioxidant defense activity and lower lipid peroxidation through water retention in leaf tissues. [Copyright &y& Elsevier]

In order to understand how salicylic acid (SA) is involved in modulating rice responses to cadmium (Cd) toxicity, particularly in Cd immobilization, a series of hydroponic experiments were conducted to examine changes in cell wall composition, activities of the enzymes related to lignin synthesis including phenylalanine ammonia-lyase (PAL), peroxidase (POD), and polyphenol oxidase (PPO), subcellular Cd distribution, levels of hydrogen peroxide (H2O2), malondialdehyde (MDA), and lignin and non-protein thiols (NPT) in rice roots under Cd stress with or without the pretreatment of SA. Results showed that Cd treatment decreased root biomass by 40% compared with the control (no Cd treatment) and pretreatment with SA significantly mitigated the Cd-induced inhibition of root growth. There was no significant difference in root cell wall composition or lignification between the treatment with Cd alone and the treatment with Cd with SA. No effects were observed for SA pretreatment on the activities of PAL, POD, or PPO under Cd stress. Furthermore, soluble Cd concentrations in root cells were significantly higher in the treatment with Cd with SA than in the treatment with Cd alone. However, H2O2 and MDA concentrations in rice roots were significantly lower but NPT levels were higher in the treatment with Cd with SA than in the treatment with Cd alone, which indicated that SA alleviated Cd-induced oxidative damage. It seems to suggest that SA-mediated enhancement of Cd tolerance was not due to enhanced Cd retention in the cell wall but to enhanced Cd bindings with thiols (─SH) group. The effects of SA-enhanced Cd tolerance were discussed with regard to H2O2 signaling pathways. [ABSTRACT FROM AUTHOR]

Abstract: Silicon (Si) is generally considered a beneficial element for the growth of higher plants, especially for those grown under stressed environments. Recently, the mitigating role of Si in salt stress has received worldwide attention. However, its mechanisms involved remain poorly understood. We studied the effects of Si on plasma membrane fluidity, phospholipids and H+-ATPase activity and reduced glutathione (GSH) concentration with two contrasting barley cultivars differing in their salt tolerance. The results showed that plasma membrane H+-ATPase activity decreased in leaves of plants treated with 120mM NaCl, and this decrease was more obvious in salt-sensitive cultivar (Kepin No. 7) than in salt-tolerant cultivar (Jian 4). Under NaCl stress, plasma membrane fluidity decreased, and the ratio of phospholipids to proteins in plasma membrane vesicles increased. GSH concentration decreased in leaves of plants exposed to 120mM NaCl in salt-sensitive cultivar (but not in salt-tolerant cultivar). Inclusion of 1.0mM Si to the salt treatment increased plasma membrane H+-ATPase activity in both cultivars as compared with the plants treated with 120mM NaCl only. The addition of Si to salt treatment was also found to recover membrane fluidity to control (neither NaCl nor Si added) level, and decrease the ratio of phospholipids to protein. Furthermore, GSH concentration in leaves of salt-treated plants was increased by addition of Si. It is suggested that Si maintain the optimal membrane fluidity and increase GSH concentration, which contributes to reducing oxidative damage to enzymes induced by active oxygen species and enhances plasma membrane H+-ATPase activity under NaCl stress. [Copyright &y& Elsevier]

Abstract: A pot experiment was performed to compare the impact of organic manure on soil enzymatic activity, respiration rate and the growth of two barley cultivars (Hordeum vulgare L.) differing in their salt tolerance under a simulated salinized environment. A plastic pot with a hole (2cm in diameter) in the center of bottom was filled with an anthropogenic (paddy) soil and placed in a porcelain container containing NaCl solution (3.0gL−1) such that a secondary salinization process was simulated via upward capillary water movement along the soil profile. A treatment with neither organic manure nor simulated soil salinization was taken as a control (CK1). The organic manure was applied either inside or outside rhizobag made of nylon cloth (40μm of pore size). The soil was treated with: 20gkg−1 rice straw (RS), 20gkg−1 pig manure (PM), or 10gkg−1 rice straw plus 10gkg−1 pig manure (RS+PM). No organic manure was added in an additional control treatment (CK2). The results indicated that the placement of organic manure both inside and outside rihzobags significantly increased the activity of urease, alkaline phosphatase and dehydrogenase, as well as respiration rate in both rhizosphere and bulk soils. Also, nutrient uptake by barley plants was enhanced in the treatments with organic manure amended either inside or outside rhizobags. The activity of these enzymes along with the respiration rate was higher in rhizosphere than in non-rhizosphere when organic manure was supplied inside rhizobags, while the opposite was found in the case of manure incorporated outside rhizobags. Among all the treatments, RS+PM treatment had most significant stimulating effects on enzymatic and microbial activity and shoot dry weight of barley, followed by PM and RS. Moreover, more significant stimulating effects on both enzyme activity and plant growth were achieved in the treatments with manure amended inside rhizobags than outside rhizobags. The results of the present study confirmed the view that incorporation of organic manure especially into soil–root zones is an effective low-input agro-technological approach to enhancing soil fertility and minimizing phytotoxicity induced by secondary salinization. [Copyright &y& Elsevier]

We investigated the effects of silicon (Si) on time-dependent changes in root tonoplast H+-ATPase and H+-PPase activities, membrane fatty acid compositions and tonoplast fluidity in two barley (Hordeum vulgare L.) cultivars differing in salt tolerance. Plants were grown in NaCl-free (control) and NaCl-supplied (60 and 120 mM, respectively) nutrient solutions with or without 1.0 mM Si. Plant roots were harvested to isolate tonoplast vesicles for assay of H+-ATPase and H+-PPase activities at days 2, 4, and 6 after treatment in the first experiment and for analysis of membrane fatty acid composition and fluidity at day 4 after treatment in the second experiment. The results showed that tonoplast H+-ATPase and H+-PPase activities in roots of salt-treated plants increased at day 2, which was more obvious at 60 mM NaCl in the salt-tolerant cultivar than in the salt-sensitive cultivar, and then decreased at day 4 and onward. These enzyme activities decreased consistently from days 2 to 6 for treatment with 120 mM NaCl. However, inclusion of 1.0 mM Si significantly enhanced both H+-ATPase and H+-PPase activities in roots of salt stressed barley, which was irrespective of NaCl level or cultivar used. The ratio of unsaturated to saturated fatty acids (U/S) increased under salt stress for both cultivars. Addition of Si to salt treatment increased the ratio of U/S in salt-tolerant cultivar but it did not in salt-sensitive cultivar compared to non-Si-amended salt treatment. Salt treatment decreased tonoplast fluidity of roots of barley significantly compared with control treatment. However, root tonoplast fluidity was significantly lower in the Si-amended salt treatment than in the non-Si-amended salt treatment. These results were in line with the previous findings that Si could help increase antioxidative defense and reduce membrane lipid oxidative damage in barley under salt stress. The possible mechanisms involved in Si-enhanced salt tolerance were discussed with respect to cell membrane integrity, stability and function in barley. [Copyright &y& Elsevier]

Abstract: Pot experiments were performed to study the alleviative effects of exogenous silicon (Si) on cadmium (Cd) phytotoxicity in maize grown in an acid soil experimentally contaminated with Cd. Five treatments were investigated in the first trial consisting of a control (neither Cd nor Si added), Cd added at 20 or 40mgkg−1 Cd without or with Si added at 400mgkg−1 Si. A following-up trial was conducted with almost the same treatments as in the first trial except that Si was incorporated at 50mgkg−1 Si. The results showed that Cd treatment significantly decreased shoot and root dry weight, while addition of Si at both levels significantly enhanced biomass. Addition of Si at 400mgkg−1 Si significantly increased soil pH but decreased soil Cd availability, thus reducing Cd concentration in the shoots and roots and total Cd in the shoots. Moreover, more Cd was found to be in the form of specific adsorbed or Fe–Mn oxides-bound fraction in the Si-amended soil. In contrast, soil pH, available Cd and Cd forms were unaffected by addition of Si at 50mgkg−1 Si, but shoot Cd concentration in the Si-amended Cd treatments significantly decreased at both Cd levels used compared to the non-Si-amended Cd treatments. Total Cd in the shoots and roots was considerably and significantly higher in the Si-amended Cd treatments than in the non-Si-amended Cd treatments. The xylem sap significantly increased but Cd concentration in the xylem sap significantly decreased in the Si-amended Cd treatments compared with the non-Si-amended Cd treatments irrespective of Cd and Si levels used. The results suggest that Si-enhanced tolerance to Cd can be attributed not only to Cd immobilization caused by silicate-induced pH rise in the soils but also to Si-mediated detoxification of Cd in the plants. [Copyright &y& Elsevier]

We describe briefly, the mechanism and characteristics of a versatile new photochromic molecule that is capable of performing as a medium for non-destructible high capacity readout molecular storage devices. This molecular memory consists of two different molecular components, chemically bonded together. It retains the photochromic and spectroscopic properties of each individual molecular component and the changes in the property of one component influence the fluorescence quantum yield of the other. The write form is a polar closed structure molecule that does not fluoresce. When transformed into the read form it exhibits an open structure, is non-polar and allows for intense fluorescence. The read form excited state is located at 660 nm, which is at lower energy than the excited state of the write form, therefore no erasing occurs while reading. Erasing is achieved by excitation at 400 nm, which is higher than 530 nm write energy. The write/read/erase spectra and mechanism have been measured in solution and in solid polymer, including PMMA matrices. [Copyright &y& Elsevier]

Pot experiments were conducted with rice and barley to investigate the influence of incorporated organic manure in an anthropogenic (paddy) soil on the enzymatic and biological activities and on the growth and mineral composition of plants. The soil used for the experiments was sampled in the coastal zone of eastern Jiangsu Province, China. The soil was an anthropogenic derived from alluvial and marine deposits. Four treatments, consisting of 20 g kg−1 rice straw alone (RS), 20 g kg−1 pig manure alone (PM), 20 g kg−1 rice straw plus 20 g kg−1 pig manure (RS+PM), and a control (no manure added) were investigated with rice as the first and barley as the second crop. The results showed that urease activity for RS+PM, PM and RS treatments increased by 163%, 96% and 21%, respectively, compared to the control at tillering stage of rice. Similar results were obtained at jointing stage. During the barley season, the urease activity of RS, PM and RS+PM treatments at tillering stage increased by 57.4%, 93.1% and 152.5%, respectively, compared to the control. The incorporation of organic manure into the soil significantly (P<0.01) increased soil alkaline phosphatase activity and soil respiration rate regardless of crop species and growth stage. The addition of organic manure increased K ion but decreased Na ion uptake and transport to shoots from roots, thus enhancing K/Na selectivity ratio and salt tolerance of rice and barley plants. As a result, the dry weight of rice and barley for the treatments with organic manure significantly increased compared to the control. The incorporation of organic manure into salinised anthropogenic soil seems to be a practical and effective way to improve soil fertility, and enhance the salt tolerance and growth of crops. However, organic manure incorporated at excess dosage should be avoided, especially in a soil under long-term flooded condition, to reduce the risk of toxic effects of reduced metabolic intermediates. [Copyright &y& Elsevier]

Both pot experiment and solution culture were conducted with two contrasting oilseed rape cultivars to investigate the effects of NPK fertilization with varied boron (B) status on plant growth, nutrient uptake, root activity (as TTC reducing capacity by fresh roots) and root cell plasmalemma H+-ATPase activity. The tolerant and sensitive cultivars used were ZY 821 and WY 324, respectively. The soil used for pot experiment was an alluvial soil. The pot experiment consisted of two nitrogen–phosphorus–potassium (NPK) levels (mg kg-1 air-dried soil): high NPK with N 335; P2O5 150 and K2O 150; low NPK with N 285; P2O5 100 and K2O 100 and two B levels (as borax, mg kg-1 air-dried soil): 16 (+B) and 0 (-B, no B supply). The solution culture consisted of two B levels: 0 (-B, no B added) and 100 μmol/L (+B, added as H3BO3). Compared to the treatment with no B added, the incorporation of B into the B-deficient soil significantly increased shoot and root dry weight (DW), ratio of root to shoot (RRS), seed yield (SY), and uptake of nutrients [N, P, K, calcium (Ca), magnesium (Mg), and B], irrespective of NPK supply levels. Increasing rate of NPK could significantly decrease the parameters described above, regardless of B status. In contrast to -B treatment, addition of B to the solution obviously enhanced root activity and plasmalemma H+-ATPase activity. Under the same conditions, cultivar ZY 821 produced more DW, larger RRS, higher SY, more nutrient uptake, higher root activity and H+-ATPase activity than cultivar WY 324. It is suggested that RRS, root activity and plasmalemma H+-ATPase activity be used as useful parameters to screen oilseed rape cultivars, which are genotypically different in response to B deficiency. [ABSTRACT FROM AUTHOR]

Growth chamber studies were conducted to investigate the effects of silicon (Si) on plant growth and nutrient uptake in barley (Hordeum vulgare L.) grown hydroponically under toxic levels of aluminum (Al). Treatments were 0, 100, or 150 μmol L-1 Al (as AlCl3), and 0 or 1.0 mmol L-1 Si (as silicic acid) in Experiment A; and 0, 50, or 75 μmol L-1 Al (as AlCl3) and 0.5 or 1.0 mmol L-1 Si (as silicic acid) in Experiment B. The Al and Si treatments were arranged factorically in a randomized, complete block design with three replicates. Aluminum added significantly (P < 0.05) increased plasma membrane permeability, which was not alleviated by added Si. The addition of Si significantly (P < 0.05) reduced root length, dry weight, shoot nitrogen (N) and phosphorus (P) concentration, root N and potassium (K) concentration, and increased root P concentration of barley plants exposed to 75 μmol L-1 Al and above. Nutrient uptake was significantly inhibited when plants were grown under 75 μmol L-1 Al and above, regardless of Si. However, Si helped to alleviate the toxic effects of Al on the growth of plants grown with 50 μmol L-1 Al, thus resulting in little difference in both dry matter weight and nutrient uptake between Al-fed treatments and Al-deprived ones. Under Al stress, increased levels of Si increased shoot Al concentration, while shoot Si concentration significantly (P < 0.05) decreased with increasing Al level in nutrient solution. It can be concluded that Si alleviated the phytotoxicity of Al at a lower concentration of Al, but exaggerated it at a higher concentration of Al. Based on the literature reports and the present study, the authors believe that the effect of Si on Al-stressed plants depends upon the plant species, Al and Si levels, and the duration of plants exposed to Al stressed environment. Si-enhanced Al toxicity in barley is partly attributed to the mineral nutrient imbalances. [ABSTRACT FROM AUTHOR]

Due to the frequent occurrence of extreme weather and severe environmental pollution, food security and human survival are at risk. Silicon, a key element in plant nutrition and environmental remediation, has a variety of applications in combatting various forms of abiotic and biotic stress and fostering healthy plants and soils. To establish a silicon-based defense barrier for plants, we firstly summarized and grouped the mechanisms of silicon functioning in plants: 1) molecular regulation and overall strengthening, 2) physical barrier and apoplastic obstruction, and 3) energy conservation. Additionally, the types and applications of silicon-based materials as soil remediation materials and fertilizers were discussed. Then, the challenges to build up such a barrier were analyzed in terms of silicon absorption and transportation, deposition and aggregation, and perception and regulation. An "external + internal" strategy was proposed to accelerate the establishment of a silicon-based barrier to enhance plants' resistance to extreme weather and environmental pollution, including high temperatures, drought, ultraviolet radiation, salt, heavy metals, nutrient deficiencies, new pollutants, and biotic stress. Finally, this paper emphasized the contribution of silicon barrier to healthy Soil-Plant-Atmosphere system that eventually benefit human health. This paper highlights the current understanding and future perspectives of silicon-related research in Soil-Plant-Atmosphere system, providing a reference for the application of silicon-based materials in environmental and agricultural fields. [ABSTRACT FROM AUTHOR]

Recently, the newly synthesized septuple-atomic layer two-dimensional (2D) material MoSi2N4 (MSN) has attracted attention worldwide. Our work delves into the effect of vacancies and external electric fields on the electronic properties of the MSN/graphene (Gr) heterostructure using first-principles calculation. We find that four types of defective structures, N-in, N-out, Si and Mo vacancy defects of monolayer MSN and MSN/Gr heterostructure are stable in air. Moreover, vacancy defects can effectively modulate the charge transfer at the interface of the MSN/Gr heterostructure as well as the work function of the pristine monolayer MSN and MSN/Gr heterostructure. Finally, the application of an external electric field enables the dynamic switching between n-type and p-type Schottky contacts. Our work may offer the possibility of exceeding the capabilities of conventional Schottky diodes based on MSN/Gr heterostructures. [ABSTRACT FROM AUTHOR]

GaN is a promising third-generation semiconductor material for fabricating nanodevices with nanoscale dimensions. In particular, thick-film sensors fabricated with GaN nanoparticles (NPs) have good gas-sensing characteristics. This study used molecular dynamics simulation to investigate the effect of temperature and size on the structural morphology and surface recrystallization of GaN NPs during sintering. The diffusion behavior and changes in the structural morphology of atoms were analyzed based on the shrinkage ratio, mean square displacement, potential energy, and other methods. The results show that during sintering, the surface of two GaN NPs experienced recrystallization, which expanded with increasing temperature; however, the obvious sintering phenomenon occurred at 3000 K. Interestingly, the surface recrystallization of NPs exhibited a lamellar structure formed through a specific stacking method of the crystal structure. However, when the size of one of the two NPs was reduced, the small NP rapidly melted and was induced to crystallize into a complete NP (having the same crystal orientation as the large NP) by the large NP. Moreover, NPs underwent rigid-body rotation and relative rotation during sintering; however, plastic deformation and dislocations resulting from rotation were only found in the neck of NPs of the same size. The study results provide valuable insights at the atomic scale regarding the sintering of GaN NPs and a useful reference for preparing and processing nanodevices. [ABSTRACT FROM AUTHOR]

Salicylic acid (SA) is a phenolic phytohormone that plays a vital role in plant development and mediates plant responses to plenty of adversity including arsenic (As) stress. The effects of exogenous addition of SA on As tolerance and As accumulation were assessed in two cultivars of rice (Oryza sativa L.) Nipponbare and Zhongzao 39, hydroponically grown with Kimura B nutrient solution under arsenite [As (III)] and dimethylarsonic acid (DMA) exposure. In the second ex-periment, the influence of soaking seed with SA on As uptake and As damages was investigated in rice (cv. Nipponbare) exposed to As (III) and DMA. The results showed that exogenous addition of SA significantly decreased the concentrations of hydrogen peroxide (H2O2) and malondialdehyde (MDA) in both As (III)- and DMA-stressed rice, indicating that SA alleviates As-induced oxidative damages in rice. SA increased the activity of antioxidant enzymes and, moreover, increased the relative amount of glutathione (GSH) and ascorbate (ASA) by accelerating the GSH-ASA circle system. Exogenous addition of SA significantly decreased the As concentration in both roots and shoots of rice under As(III) stress by influencing the expression of genes encoding As transporters, viz. OsLsi1, OsLsi2. The addition of SA significantly decreased the As content in shoots under DMA stress, which may be related to the expression of OsPTR7 involved in shoot xylem unloading. This finding may foster a novel perspective for reducing As accumulation in rice grains. [ABSTRACT FROM AUTHOR]

The efficacy of nitrification inhibitors (NIs) dicyandiamide (DCD) and 3,4-dimethylpyrazole phosphate (DMPP) varies with soil types. Understanding the microbial mechanisms for this variation may lead to better modelling of NI efficacy and therefore on-farm adoption. This study addressed the response patterns of mineral nitrogen, nitrous oxide (N2O) emission, abundances of N-cycling functional guilds and soil microbiota characteristics, in relation to urea application with or without DCD or DMPP in two arable soils (an alkaline and an acid soil). The inhibition of nitrification rate and N2O emission by NI application occurred by suppressing ammonia-oxidizing bacteria (AOB) abundances and increasing the abundances of nosZI-N2O reducers; however, abundances of ammonia-oxidizing archaea (AOA) were also stimulated with NIs-added in these two arable soils. DMPP generally had stronger inhibition efficiency than DCD, and both NIs' addition decreased Nitrobacter, while increased Nitrospira abundance only in alkaline soil. N2O emissions were positively correlated with AOB and negatively correlated with nosZI in both soils and AOA only in acid soil. Moreover, N2O emissions were also positively correlated with nirK-type denitrifiers in alkaline soil, and clade A comammox in acid soil. Amendment with DCD or DMPP altered soil microbiota community structure, but had minor effect on community composition. These results highlight a crucial role of the niche differentiation among canonical ammonia oxidizers (AOA/AOB), Nitrobacter and Nitrospira, as well as nosZI- and nosZII-N2O reducers in determining the varying efficacies of DCD and DMPP in different arable soils. [ABSTRACT FROM AUTHOR]

The effects of consecutive application of chemical fertilizer with or without organic fertilizer on soil N 2 O emissions and denitrifying community structure in a drip-irrigated field were determined. The four fertilizer treatments were (i) unfertilized, (ii) chemical fertilizer, (iii) 60% chemical fertilizer plus cattle manure, and (iv) 60% chemical fertilizer plus biofertilizer. The treatments with organic amendments (i.e. cattle manure and biofertilizer) reduced cumulative N 2 O emissions by 4.9–9.9%, reduced the N 2 O emission factor by 1.3–42%, and increased denitrifying enzyme activities by 14.3–56.2%. The nirK gene copy numbers were greatest in soil which received only chemical fertilizer. In contrast, nirS - and nosZ -copy numbers were greatest in soil amended with chemical fertilizer plus biofertilizer. Chemical fertilizer application with or without organic fertilizer significantly changed the community structure of nirK -type denitrifiers relative to the unfertilized soil. In comparison, the nirS - and nosZ -type denitrifier genotypes varied in treatments receiving organic fertilizer but not chemical fertilizer alone. The changes in the denitrifier communities were closely associated with soil organic carbon (SOC), NO 3 − , NH 4 + , water holding capacity, and soil pH. Modeling indicated that N 2 O emissions in this soil were primarily associated with the abundance of nirS type denitrifying bacteria, SOC, and NO 3 − . Overall, our findings indicate that (i) the organic fertilizers increased denitrifying enzyme activity, increased denitrifying-bacteria gene copy numbers, but reduced N 2 O emissions, and (ii) nirS - and nosZ -type denitrifiers were more sensitive than nirK -type denitrifiers to the organic fertilizers. [ABSTRACT FROM AUTHOR]

Ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) co-exist in soils. However, little is known about the effects of fertilization on the AOA and AOB communities and their relative contribution to soil nitrification. The objective of this field study was to determine the effects of four years of mineral and organic fertilizer (i.e., either cattle manure or biofertilizer) application on AOB and AOA in calcareous soil. The combined application of mineral and organic fertilizer (especially cattle manure) significantly increased the species richness (Chao1 and Ace) and α- diversity (Shannon index) of AOB ( P < 0.05) but not AOA ( P = 0.102). The AOA/AOB ratios were 1.64 and 1.19 in the unfertilized and the mineral fertilizer treatments, respectively. In contrast, the AOA/AOB rations were <1.0 in treatments with both mineral and organic fertilizer. These findings indicated that organic fertilizer increased AOB comparatively to AOA. Fertilizer addition was associated with significant shifts in the community structure of AOB ( P < 0.01) but had little effect on AOA. Soil potential nitrification rate were greatly increased by the application of either mineral fertilizer or mineral plus organic fertilizer ( P < 0.05). Moreover, potential nitrification rate were positively correlated with AOB abundance ( P < 0.001) but not AOA abundance ( P = 0.223). Variations in AOB community structure were closely associated with fertilizer-induced changes in soil pH, NH 4 + and SOC, whereas AOA community structure was only significantly correlated with SOC ( P = 0.040). Our findings suggest (i) that AOB is more sensitive than AOA to different fertilization regimes and (ii) that AOB contribute more than AOA to nitrification in this fertilized calcareous field soil. [ABSTRACT FROM AUTHOR]

The Hall–Petch relationship and deformation process in Ti3Al nano-polycrystalline alloys are investigated using molecular dynamics simulations in this research. The impact of different grain sizes and temperatures on mechanical characteristics was considered. Different Hall–Petch relations were detected for samples with the grain sizes ranging from 2 to 20 nm, inverse Hall–Petch relations in big grain sizes ranges, and positive Hall–Petch relations in the medium grain size region, respectively. A transition zone formed at the interception of positive and inverse Hall–Petch relations, which will vanish as the temperature rises. The critical grain size of the positive Hall–Petch relation decreases as the temperature rises from 10 to 600 K. With the grain size increases in the smaller grain size range, the yield stress increases, which is made by the grain boundary motion and rotation. Besides, temperatures affect mechanical characteristics. The rising temperatures lead to the decreasing dislocation density and a high grain boundary fraction. [ABSTRACT FROM AUTHOR]

In the realm of semiconductor materials, the integration of graphene (Gr) and gallium nitride (GaN) has emerged as a promising avenue for enhancing device performance. In this study, a Gr/GaN layered nanocomposite was constructed using molecular dynamics simulation and the LAMMPS code. Diamond abrasive was pressed into the composite at a speed of 50 m/s at 300 K, followed by ultrasonic vibration-assisted polishing on the (0001) plane along the [ 0 1 ‾ 10 ] direction. By rigorously exploring various factors such as number of Gr layers, vibration amplitudes, vibration frequencies and grinding speeds, the study elucidates the intricate mechanisms governing material removal and subsurface damage. Key findings reveal optimal processing conditions, including three layers of Gr, an amplitude of 5 Å, a vibration frequency of 80 GHz and a grinding speed of 100 m/s, which result in enhanced material removal rates and improved surface quality. Additionally, the insertion of Gr layers within the GaN matrix demonstrates a remarkable reduction in friction and wear rates, highlighting the potential for enhancing device reliability and performance. This comprehensive investigation not only advances our understanding of ultrasonic vibration-assisted grinding processes but also underscores the transformative impact of Gr/GaN composites in semiconductor device fabrication. [Display omitted] • Graphene-containing composites exhibit enhanced wear resistance and reduced wear rate. • Temperature and friction variations in UVAP resemble sinusoidal patterns. • The graphene layer presence results in nearly uniform thickness of the subsurface damage layer. • Higher amplitudes result in increased material removal, albeit with higher severity of subsurface damage layers. • Elevated velocities raise regional temperature, affecting atom removal quantity and subsurface quality. [ABSTRACT FROM AUTHOR]

The discovery of comammox Nitrospira has altered our perception of the nitrogen biogeochemical cycle. However, their functional importance compared to canonical ammonia oxidisers (i.e., ammonia-oxidising bacteria (AOB) and archaea (AOA)) in agricultural soils remains elusive, especially in acidic soils. Here, we assessed the functional importance of these functional guilds in nitrification and nitrous oxide (N 2 O) emissions in three acidic agricultural soils by using a range of nitrification inhibitors (acetylene, 3,4-dimethylpyrazole phosphate (DMPP) and different concentrations of 1-octyne) and monitored their community assemblage and population dynamics. The sensitivity of comammox Nitrospira clade A to 1-octyne varied across soils, highlighting that the inappropriate use of 1-octyne can lead to misestimation of comammox activity. AOA were key NH 3 oxidisers in the three soils, while AOB also contributed significantly to nitrification in one soil. In contrast, comammox Nitrospira always played a minor role in ammonia oxidation and N 2 O emissions, likely due to their low abundances, restricted cellular kinetic properties and N 2 O production mechanisms. Together, this study demonstrates that comammox Nitrospira play a less important role in ammonia oxidation and N 2 O production in acidic agricultural soils than AOA and AOB, thereby providing important novel insights into the mitigation of nitrogen fertiliser loss and N 2 O emissions. • Comammox play a minor role in NH 3 oxidation and N 2 O emissions in acidic arable soils. • AOB are functionally active in acidic agricultural soils. • The sensitivity of comammox Nitrospira clade A to 1-octyne varies across soils. [ABSTRACT FROM AUTHOR]

• The topologically close–packed (TCP) atoms dominate in undercooled Zr liquid. • The TCP atoms are energetic and structural favourable and then stabilize super-cooled liquid. • Three stages between TCP and BCC competition process can be observed. • Crystallization cannot occur until the TCP atoms with T 5 > 1/3 drops in number and interconnect. The crystallization of undercooled liquid zirconium (Zr) during isothermal relaxation was investigated by molecular dynamics simulation. In particular, the dynamic competition mechanism between the topologically close–packed (TCP) and body–centered cubic (BCC) structures during crystallization was deeply studied using the atomic energy, the pair distribution function and the largest standard cluster analysis (LaSCA). The study found that TCP clusters, rather than icosahedral clusters, play an important role in hindering the crystallization of the undercooled liquid. The TCP clusters with T 5 = n 5 /(n 4 + n 5 + n 6) > 1/3 (where n 4 , n 5 and n 6 represent the number of common neighbor sub-cluster: 444, 555 and 666 respectively) stabilize the undercooled liquid and prevent crystallization; while the other TCPs exhibits an evolution trend similar to that of BCC-like clusters. Furthermore, three stages of the competition process between TCP and BCC structures can be observed, and crystallization does not happen until the number of major TCP clusters with T 5 > 1/3 decreases and the average degree of interconnection among them weakens. [ABSTRACT FROM AUTHOR]

• With a crystallization-like E-T curve Ni 50 Ag 50 amorphization includes a LLT and a LST. • The average cutoff distance exported by LaSCA is useful in identifying state transitions. • LLT can be identified by the evolution of SRO and MRO structures, where MRO shows the glass feature. • In LST, TCP-based MRO and TLRO structures grow rapidly. • TCP structures reflect the essential nature of amorphous systems more effectively than ICOs. A molecular dynamics simulation of rapid cooling at a cooling rate of 1011 K/s for Ni 50 Ag 50 alloys was conducted. The rapid cooling process was analyzed by using the system energy, the pair distribution function, and the largest standard cluster analysis. It is found that with a crystallization-like energy curve the solidification of Ni 50 Ag 50 alloy experiences a liquid-liquid and a liquid-solid transition (LLT and LST), finally result in an amorphous solid. In LLT stage the topologically close-packed (TCP) short-range order structures of both crystal (S666) and glass (S555) increase; whereas only glass medium-range order structures are formed. TCP-based long-range order (LRO) structures of glass do not increase until the beginning of the LST. Even in solid (T < T g) the LRO parameter based on ICO structures fluctuates violently, while that based on TCP structures is quite stable. Therefore, TCP not only is the basic structural characteristics of disordered system but also reasonably represents the metastability of metallic glasses. These findings not only clarify the importance of LLT for the glass forming ability of alloys, but also fully demonstrate the effectiveness and necessity of TCP structures for describing the structure of amorphous systems. [ABSTRACT FROM AUTHOR]

Two-phase Îł -TiAl/ α 2-Ti3Al lamellar intermetallics have attracted considerable attention because of their excellent strength and plasticity. However, the exact deformation mechanisms remain to be investigated. In this paper, a solidified lamellar Tiâ€"Al alloy with lamellar orientation at 0°, 17°, and 73° with respect to the loading direction was stretched by utilizing molecular dynamics (MD) simulations. The results show that the mechanical properties of the sample are considerably influenced by solidified defects and tensile directions. The structure deformation and fracture were primarily attributed to an intrinsic stacking fault (ISF) accompanied by the nucleated Shockley dislocation, and the adjacent extrinsic stacking fault (ESF) and ISF formed by solidification tend to form large HCP structures during the tensile process loading at 73°. Moreover, cleavage cracking easily occurs on the Îł / α 2 interface under tensile deformation. The fracture loading mechanism at 17° is grain boundary slide whereas, at 73° and 0°, the dislocation piles up to form a dislocation junction. [ABSTRACT FROM AUTHOR]

Silicon (Si) can alleviate aluminum (Al) toxicity in rice (Oryza sativa L.), but the mechanisms underlying this beneficial effect have not been elucidated, especially under long-term Al stress. Here, the effects of Al and Si on the suberization and development of rice roots were investigated. The results show that, as the Al exposure time increased, the roots accumulated more Al, and Al enhanced the deposition of suberin in roots, both of which ultimately inhibited root growth and nutrient absorption. However, Si restricted the apoplastic and symplastic pathways of Al in roots by inhibiting the uptake and transport of Al, thereby reducing the accumulation of Al in roots. Meanwhile, the Si-induced drop in Al concentration reduced the suberization of roots caused by Al through down-regulating the expression of genes related to suberin synthesis and then promoted the development of roots (such as longer and more adventitious roots and lateral roots). Moreover, Si also increased nutrient uptake by Al-stressed roots and thence promoted the growth of rice. Overall, these results indicate that Si reduced Al-induced suberization of roots by inhibiting the uptake and transport of Al in roots, thereby amending root growth and ultimately alleviating Al stress in rice. Our study further clarified the toxicity mechanism of Al in rice and the role of Si in reducing Al content and restoring root development under Al stress. [ABSTRACT FROM AUTHOR]

Soil contamination by heavy metals has become a serious threat to global food security. The application of silicon (Si)-based materials is a simple and economical method for producing safe crops in contaminated soil. However, the impact of silicon on the heavy-metal concentration in plant roots, which are the first line in the chain of heavy-metal entering plants and causing stress and the main site of heavy-metal deposition in plants, remains puzzling. We proposed a process-based model (adsorption-diffusion model) to explain the results of a collection of 28 experiments on alleviating toxic metal stress in plants by Si. Then we evaluated the applicability of the model in Si-mitigated trivalent chromium (Cr[III]) stress in rice, taking into account variations in experimental conditions such as Cr(III) concentration, stress duration, and Si concentration. It was found that the adsorption-diffusion model fitted the experimental data well (R2 > 0.9). We also verified the binding interaction between Si and Cr in the cell wall using SEM-EDS and XPS. In addition, we designed a simplified biomimetic device that simulated the Si in cell wall to analyze the dual-action switch of Si from increasing Cr(III) adsorption to blocking Cr(III) diffusion. We found that the adsorption of Cr(III) by Si decreased from 58% to 7% as the total amount of Cr(III) increased, and finally the diffusion blocking effect of Si dominated. This study deepens our understanding of the role of Si in mitigating toxic metal stress in plants and is instructive for the research and use of Si-based materials to improve food security. [Display omitted] • Si reduces toxic metal concentration in shoots but sometimes increases it in roots. • The adsorption-diffusion model was developed to explain the effect of Si in roots. • Si exhibited dual roles in roots by increasing adsorption and blocking diffusion. • The intensity and duration of stress and Si concentration affected Si's function. [ABSTRACT FROM AUTHOR]

Silicon (Si) has been well-known to enhance plant resistance to heavy-metal stress. However, the mechanisms by which silicon mitigates heavy-metal stress in plants are not clear. In particular, information regarding the role of Si in mediating resistance to heavy-metal stress at a single cell level is still lacking. Here, we developed a hierarchical system comprising the plant, protoplast, and suspension cell subsystems to investigate the mechanisms by which silicon helps to alleviate the toxic effects of trivalent chromium [Cr(III)] in rice. Our results showed that in whole-plant subsystem silicon reduced shoot Cr(III) concentration, effectively alleviating Cr(III) stress in seedlings and causing changes in antioxidant enzyme activities similar to those observed at lower Cr(III) concentrations without silicon added. However, in protoplast subsystem lacking the cell wall, no silicon deposition occurred, leading to insignificant changes in cell survival or antioxidation processes under Cr(III) stress. Conversely, in suspension cell subsystem, silicon supplementation substantially improved cell survival and changes in antioxidant enzyme activities under Cr(III) stress. This is due to the fact that >95% of silicon was on the cell wall, reducing Cr(III) concentration in cells by 7.7%–10.4%. Collectively, the results suggested that the silicon deposited on the cell wall hindered Cr(III) bio-uptake, which consequently delayed Cr(III)-induced changes in antioxidant enzyme activities. This research emphasizes the significance of cell walls in Si-alleviated heavy-metal stress and deepens our understanding of silicon functioning in plants. Furthermore, the hierarchical system has great potential for application in studying the functioning of other elements in plant cell walls. [Display omitted] • A hierarchical system was developed to explore the Si functioning mechanism. • The system includes three subsystems: plant, protoplast, and suspended cell. • Si affects rice seedlings' antioxidant enzyme activity by reducing Cr(III) uptake. • Silicon presents different roles on protoplasts and suspension cells. • 95% of Si is on cell walls of suspension cells and acts as a defense barrier. [ABSTRACT FROM AUTHOR]

Phosphorus (P) accumulation in croplands resulting from ever-increasing input of P fertilizer strongly influences soil microbial growth and activities, which is expected to alter the soil priming effect (PE) induced by plant residue. However, the effect of P availability on the magnitude and direction of PE remains largely unexplored and the underlying microbial mechanisms are still unclear. Therefore, a 40-day incubation experiment was established by adding C4-maize straw to C3-soils with or without long-term P fertilizer inputs to investigate PE and accompanied dynamics of microbiota. The results revealed that in both soils, straw application caused positive real PEs via a "microbial co-metabolism" mechanism, accompanied by a microbial succession from the dominance of r- and K-strategists to K-strategists (mainly fungi). In addition, long-term amendment with P increased PE by 83.2% compared with no P fertilization control, which was mainly mediated by K-strategists, especially the fungal families Chaetomiaceae and Myrmecridiaceae. The increased PE was accompanied by enhanced microbial biomass carbon, extracellular enzyme activities, and bacterial gene abundance, confirming the "stoichiometric decomposition" theory. Meanwhile, deviating from the conventional paradigm, higher phosphatase activity and lower enzymatic stoichiometry of carbon (C)-to-P ratios in high-P soil compared with that in low-P soil suggested stronger "P mining" with high-P availability. [ABSTRACT FROM AUTHOR]

High‐quality TiAl alloy is used to fabricate aerospace equipment with excellent mechanical properties because of its interesting properties, including low density, high specific yield strength, and better corrosion resistance. However, the fabrication of high‐quality TiAl alloy is challenging because the connection mechanism between different types of clusters in TiAl alloy during the rapid cooling process is not clear. This study uses molecular dynamics (MD) simulation methods to study the connection models of icosahedral (ICO) structures and other defective ICO structures at different cooling rates. The ICO structures represent the short‐range ordered structure in the system. Moreover, the complex connections between the ICO and its defective structures constitute the basic structural features of TiAl metallic glass. The results show that the connections between ICO and its defective structures differ significantly with the cooling rate. It is easier to form a more complex nanostructure connected by the ICO structures with higher proportion of Al central atoms at the lower cooling rate. As the temperature drops at the same rate, the number of Al central atoms with smaller atomic radius in the icosahedrons increases gradually, giving them an absolute advantage. [ABSTRACT FROM AUTHOR]

Uptakes of o-chlorophenol (CP), 2,4-dichlorophenol (DCP), trichloroethylene (TCE), and atrazine (ATR), as single and mixed contaminants, by roots and shoots of rice seedlings (Oryza sativa L.) from hydroponic solutions were measured following a 48-h exposure of plant roots. As single contaminants, the concentrations of CP, DCP, and ATR in rice roots and shoots increased significantly with increasing concentrations in external solutions; however, TCE concentrations in rice roots and shoots decreased with increasing external TCE concentration or the exposure time. The observed bioconcentration factors (BCFs) of CP and DCP with roots and the BCF of ATR with shoots approximated the equilibrium values according to the partition-limited model. The BCF of DCP with shoots was about 30% of the partition limit, due to insufficient water transport into plants for DCP. In the ATR–CP–DCP mixed system, the BCFs of CP and DCP with both roots and shoots decreased significantly with increasing contaminant concentrations due to the enhanced mixed-contaminant phytotoxicity, as manifested by the greatly reduced plant transpiration rate. In the ATR–CP–DCP mixture system, the BCFs of ATR with roots at low concentrations were comparable with those for ATR alone, whereas the BCFs increased at high concentrations for an unknown reason. In the TCE-DCP system, TCE concentrations in roots increased with increasing TCE in external solutions, while TCE concentration in shoots stayed steady because of the strong TCE exchange at the air-leaf interface. The BCF of DCP with roots was comparable with that of DCP alone because there was no significant effect of added TCE on the plant transpiration rate. [Copyright &y& Elsevier]

Research on the structural properties of silicon crystal nucleation during solidification has been the subject of numerous classic studies in condensed matter physics and material science. The approach to structural properties of Si crystal nucleation adopted for this paper is based on molecular dynamics simulation at the cooling rate of 1010 K/s. Using the entropy of largest standard cluster and the pair distribution function, it is able to obtain microstructural evolution characteristics. The pleomorphism properties and distribution of Si crystal nucleation was presented by the visualization method. The systematic evolution diagram illustrates the competitive growth between cubic diamond and hexagonal diamond structures which shows that the crystal nucleus easily forms and then grow during a short period of time at the initial crystallization stage. The orientation characteristics after crystal nucleation in space are systematically analyzed and it is found that the nucleation and orientation of crystals are weakly dependent, that is, the orientations of crystals are homogeneous and random. In addition, the visualization results show that various twins exist in the system, including coherent twins, rotating twins and some torsional twins, which improve the structural stability to a certain degree. This study further explores crystal nucleation on the atomic scale and it is hoped that this research will contribute to expanding the understanding of the orientation distribution and crystallization behavior of amorphous silicon during the growth process. [ABSTRACT FROM AUTHOR]