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Pressure, a fundamental thermodynamic variable, can generate two essential effects on materials. First, pressure can create new high-pressure phases via modification of the potential energy surface. Second, pressure can produce new compounds with unconventional stoichiometries via modification of the compositional landscape. These new phases or compounds often exhibit exotic physical and chemical properties that are inaccessible at ambient pressure. Recent studies have established a broad scope for developing materials with specific desired properties under high pressure. Crystal structure prediction methods and first-principles calculations can be used to design materials and thus guide subsequent synthesis plans prior to any experimental work. A key example is the recent theory-initiated discovery of the record-breaking high-temperature superhydride superconductors H3S and LaH10 with critical temperatures of 200 K and 260 K, respectively. This work summarizes and discusses recent progress in the theory-oriented discovery of new materials under high pressure, including hydrogen-rich superconductors, high-energy-density materials, inorganic electrides, and noble gas compounds. The discovery of the considered compounds involved substantial theoretical contributions. We address future challenges facing the design of materials at high pressure and provide perspectives on research directions with significant potential for future discoveries., This work summarizes and discusses recent progress in the theory-oriented discovery of new materials under high pressure, including hydrogen-rich superconductors, high-energy-density materials, inorganic electrides, and noble gas compounds.

Cadmium accumulation in rice is a major source of Cd exposure in humans worldwide. A three-year field experiment was conducted to investigate the ecological safety and long-term stability of biochar combined with lime or silicon fertilizer for Cd immobilization in a polluted rice paddy. The results showed that the application of combined ameliorants could reduce the Cd content in brown rice to meet the Chinese maximum permissible limit for Cd content in food products (0.2 mg/kg). In addition, such amendments stimulated metabolic pathways in soil bacteria, including carbon metabolism, citrate cycle, pyruvate metabolism, biosynthesis of amino acids, and glycolysis/gluconeogenesis, revealing improvements in soil biological activity and soil health. Therefore, the results provide a practical strategy for the safe utilization of farmland with mild levels of heavy metal pollution.

The present study aimed to compare the responses of two rice cultivars to titanium dioxide nanoparticles (nTiO2), in plant performance and root-associated soil microbes, and provide a reference for the selection of nanoparticle-responsive varieties. The field experiment was conducted to study the effects of nTiO2 (applied at 200 mg/kg) on typical Chinese rice cultivars, Wuyunjing23 (WYJ23) and Yongyou2640 (YY2640), for the whole life cycle. We evaluated agronomic and physiological parameters including chlorophyll content and antioxidant enzyme activities at the heading stage, and biomass, Ti, and nutrient elements uptake after harvest. Soil bacterial communities were also measured through 16S rRNA gene sequencing. Exposure to nTiO2 led to neither Ti accumulation nor changed biomass in either cultivar, but it increased root Fe uptake and reduced grain Cu content. Specifically, nTiO2 exposure decreased the chlorophyll content but increased the peroxidase activity in WYJ23; such altered physiology might affect root exudates and further modify bacterial communities. Although nTiO2 did not induce visible phytotoxicity in YY2640, it affected the abundance of bacteria genera associated with N turnover and plant-C-metabolizing (e.g., Geobacter and Gaiella), resulting in changed C and N cycling in the rhizosphere. This study revealed divergent responses of WYJ23 and YY2640 to nTiO2, both in plant physiology and rhizosphere system. nTiO2 induced greater physiological response but affected the rhizosphere little in WYJ23. By contrast, nTiO2 changed soil microbes and enzyme activities without affecting the physiology of YY2640, suggesting its superior adaptivity to nTiO2.

Element B in binary metal borides forms various polymetric configurations due to its electron-deficient nature. Here we predict a new pressure-stabilized boron clathrate structure, LaB8, that is recoverable under ambient conditions. Crystal structure searches and first-principles calculations predict a series of thermodynamically stable La–B compounds at high pressures. Besides known LaB4 and LaB6 compounds, trigonal LaB8 is predicted to be thermodynamically stable above 70 GPa. Its B atoms construct face-sharing B26 cages, each surrounding a central La atom. The compound can be recovered to ambient conditions with the B26 cages well preserved. Electron–phonon coupling calculations suggest that it is potentially superconducting with an estimated Tc of 5 K at 70 GPa, which increases to ∼20 K at ambient pressure. The enhanced Tc is attributed to the increased B-derived electronic density of states at the Fermi level and to the softened Eu mode related to vibration of the B26 cages.

There is great economic and environmental value in recovering valuable metal ions from spent lithium-ion batteries (LIBs). A novel method that employs organic acid recovery using citric acid and salicylic acid was used to enhance the leaching of metal ions from the cathode materials of spent LIBs. The effects of the acid concentration, reducing agent content, solid to liquid (S : L) ratio, temperature, and leaching time were systematically analyzed and the optimal acid leaching process condition was determined through the results. The kinetics of the leaching process with different temperatures was analyzed to explore and verify the relationship between the leaching mechanism and temperature. The results of TG/DSC analysis showed that the optimum calcination temperature was 500 °C for 1 h and 600 °C for 3 h. The XRD and micromorphology analysis results showed that cathode material powders without impurities were obtained after pretreatment. The experimental results demonstrated that the optimal leaching efficiencies of the metals ions were 99.5% Co and 97% Li and the optimal corresponding condition was 1.5 M citric acid, 0.2 M salicylic acid, a 15 g L−1 S : L ratio, 6 vol% H2O2, 90 °C, and 90 min. Afterward, the infrared tests and SEM morphologies results indicated that only salicylic acid was present in the residue after filtration because of the microsolubility of the salicylic acid. Finally, it was obvious that the temperature had a great influence on the leaching process as observed through the kinetics and thermodynamics analyses, while the Ea values for Co and Li were obtained as 37.96 kJ mol−1 and 25.82 kJ mol−1 through the kinetics model. The whole process was found to be efficient and reasonable for recovering valuable metals from the industrial electrodes of spent LIBs.

The recent discovery of superconductivity near room temperature in highly compressed superhydrides highlights the key role of the hydrogen cage structure in determining the high superconducting critical temperature. Here, we propose a hitherto unknown metastable cage boron allotrope possessing high superconductivity at ambient pressure. Using first-principles calculations with structure searching, we have predicted various dynamically stable structures for MnB12 that can be possibly synthesized at high pressures and high temperatures. Among these structures the tetragonal t-MnB12 contains unique B16 cages, which are linked to each other to form open channels filled with Mn atoms. The removal of Mn atoms leads to the formation of a tetragonal cage boron allotrope t-B, which possesses partial ionicity due to the slight charge transfer between two inequivalent B atoms. t-B is a potential superconductor with an estimated critical temperature of 43 K, the highest value in elemental superconductors at ambient pressure.

Increasing CO2 levels are speculated to change the effects of engineered nanomaterials in soil and on plant growth. How plants will respond to a combination of elevated CO2 and nanomaterials stress has rarely been investigated, and the underlying mechanism remains largely unknown. Here, we conducted a field experiment to investigate the rice (Oryza sativa L. cv. IIyou) response to TiO2 nanoparticles (nano-TiO2, 0 and 200 mg kg-1) using a free-air CO2 enrichment system with different CO2 levels (ambient ∼370 μmol mol-1 and elevated ∼570 μmol mol-1). The results showed that elevated CO2 or nano-TiO2 alone did not significantly affect rice chlorophyll content and antioxidant enzyme activities. However, in the presence of nano-TiO2, elevated CO2 significantly enhanced the rice height, shoot biomass, and panicle biomass (by 9.4%, 12.8%, and 15.8%, respectively). Furthermore, the Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis revealed that genes involved in photosynthesis were up-regulated while most genes associated with secondary metabolite biosynthesis were down-regulated in combination-treated rice. This indicated that elevated CO2 and nano-TiO2 might stimulate rice growth by adjusting resource allocation between photosynthesis and metabolism. This study provides novel insights into rice responses to increasing contamination under climate change.

The recent successful findings of H3S and LaH10 compressed above 150 GPa with a record high Tc (above 200 K) have shifted the focus on hydrogen-rich materials for high superconductivity at high pressure. Moreover, some studies also report that transition-metal ternary hydrides could be synthesized at a relatively low pressure (∼10 GPa). Therefore, it is highly desirable to investigate the crystal structures of ternary hydrides compounds at high pressure since they have been long considered as promising superconductors and hydrogen-storage materials with a high Tc, and can be possibly synthesized at low pressure as well. In this work, combining state-of-the-art crystal structure prediction and first-principles calculations, we have performed extensive simulations on the crystal structures of YSHn (n = 1–10) compounds from ambient pressure to 200 GPa. We uncovered three thermodynamically stable compounds with stoichiometries of YSH, YSH2, and YSH5, which became energetically stable at ambient pressure, 143, and 87 GPa, respectively. Remarkably, it is found that YSH contains monoatomic H atoms, while YSH2 and YSH5 contain a mixture of atomlike and molecular hydrogen units. Upon compression, YSH, YSH2, and YSH5 undergo a transition from a semiconductor to a metallic phase at pressures of 168, 143, and 232 GPa, respectively. Unfortunately, electron–phonon coupling calculations reveal that these compounds possess a weak superconductivity with a relatively low Tc (below 1 K), which mainly stem from the low value of density of states occupation at the Fermi level (EF). These results highlight that the crystal structures play a critical role in determining the high-temperature superconductivity.

The search for two-dimensional superconductors has attracted increasing interest because of their potential applications in constructing nanoscale superconducting devices. Through swarm-intelligence based CALYPSO method and the first-principles calculations, we have identified a monolayer structure for yttrium sulfide (t-YS), which is energetically and dynamically stable. The application of biaxial strain turns t-YS to a Bardeen–Cooper–Schrieffer superconductor, which mainly originates from the softening of in-plane modes of Y atoms. The superconducting critical temperature increases monotonously with strain, which reaches 6 K at a maximum strain of 10%. Calculations show that doping at 0.3 holes per unit cell based on a strain of 10% could further enhance the superconductivity to 7.3 K. Simulations have helped to propose a candidate substrate with ∼8.3% lattice mismatch to obtain superconductive t-YS experimentally. The findings will enrich two-dimensional superconductors and stimulate immediate experimental interest.

Materials possessing both superhard and metallic properties are beneficial for the creation of multifunctional devices under extreme conditions. Here, we report the formation of a new metallic superhard boron nitride at high pressure with stoichiometry B2N3 through first-principles calculations and structure searching. At ambient pressure, B2N3 has layered structures (h-B2N3) consisting of hexagonal B4N4 layers intercalated by triply bonded N2 molecules. With the pressure increasing to ∼10 GPa, h-B2N3 transforms to a three-dimensional tetragonal structure (t-B2N3) with the formation of single N–N bonds. Calculations reveal that t-B2N3 can be recovered under ambient conditions in view of the dynamical, thermal and mechanical stability. Interestingly, t-B2N3 is proposed to be a superhard material with an estimated Vicker's hardness of ∼52 GPa by performing stress–strain calculations. More importantly, electronic calculations show unique two-dimensional metallicity in t-B2N3, which originates from the π orbitals of N–N bonds spreading in the ab plane. In addition, the energy density of ∼2.95 kJ g−1 makes t-B2N3 a potential high-energy density material.

Ovothiols are thiol-histidines that play important roles in protecting cells against oxidative stresses. Because of challenges faced in their chemical synthesis, biosynthesis provides an alternative option. In ovothiol biosynthesis, a nonheme iron enzyme (OvoA) catalyzes a four-electron oxidative coupling between l-His and l-Cys. There are debates in the literature over whether oxidative C–S bond formation or sulfur oxidation is the first half of OvoA-catalysis. In this report, by incorporating a tyrosine analogue, 2-amino-3-(4-hydroxy-3-(methoxyl) phenyl) propanoic acid (MeOTyr), via an amber-suppressor method, we modulated the rate-limiting steps of OvoA-catalysis and observed an inverse deuterium KIE for [U-2H5]-His. In conjunction with the reported quantum mechanics/molecular mechanics (QM/MM) studies, our results suggest that Y417 plays redox roles in OvoA-catalysis and imply that oxidative C–S bond formation is most likely the first half of the OvoA-catalysis.

A novel β-cyclodextrin pendant polymer (ε-PL-CD), composed of poly(ε-lysine) (ε-PL) main chain and glycine-β-cyclodextrin (Gly-CD) side chains, was prepared by a simple two-step procedure. The ε-PL-CD was investigated as a drug carrier of hydrophobic drug scutellarin (SCU). The characterization and complexation mode of the SCU:ε-PL-CD were researched in both solution and solid state by means of photoluminescence spectroscopy, 1H and 2D NMR, X-Ray powder diffraction (XRPD), thermal gravimetric analysis, Particle size and Zeta potential. The solubility test indicated that the solubilizing ability of SCU:ε-PL-CD was significantly improved compared with SCU:β-CD and free SCU. Besides, in vitro cell experiment, it was found that SCU:ε-PL-CD has a strong inhibitory effect on the growth and invasion of tumor cells. The present study provides useful information for ε-PL-CD as a drug carrier material.

Rising CO2 levels will change the behavior and toxicity of soil contaminants. However, it remains unclear whether elevated CO2 levels will change the nanoparticle dissolution or their biological effects in soil. In this study, we used a free-air CO2 enrichment system to examine the effects of elevated CO2 on phytotoxicity and bacterial toxicity of zinc oxide nanoparticles (nZnO) in a paddy soil system. The elevated CO2 changed the nZnO diffraction in soil, slightly increasing its dissolution but remarkably improving its bioavailability. Elevated CO2 did not change Zn accumulation in rice, but still alleviated the adverse effects of nZnO on rice growth, although grain protein, K and P decreased. Moreover, nZnO alone significantly decreased the number of observed soil bacterial species and altered the community organization, while elevated CO2 moderated such changes. Overall, these results increase our understanding of plant response and microbial variation in nanoparticle-contaminated soil under elevated-CO2 conditions. It is necessary to pay attention to soil pollution while facing climate change.

The design of two-dimensional superconductors has attracted great research interest owing to their wide application in nanoscale devices. Here, we combine first-principles calculations with structure searching technology to identify a unique stable hexagonal $h\text{\ensuremath{-}}{\mathrm{MnB}}_{3}$ monolayer, exhibiting a slightly higher energy with respect to the reported tetragonal $t\text{\ensuremath{-}}{\mathrm{MnB}}_{3}$. Interestingly, $h\text{\ensuremath{-}}{\mathrm{MnB}}_{3}$ contains two boron kagome layers sandwiched with Mn atoms. It exhibits metallic properties and has a superconducting transition temperature of 24.9 K, which is much higher than 2.9 K in $t\text{\ensuremath{-}}{\mathrm{MnB}}_{3}$. Its superconductivity mainly originates from the coupling between in-plane vibrational phonons of boron kagome layers and electrons of Mn atoms. $h\text{\ensuremath{-}}{\mathrm{MnB}}_{3}$ exhibits a tunable superconductivity, and reaches a maximum of 34 K at 2% tensile strain resulting from the softening in-plane modes of boron kagome layers. The Si (111) surface may be an ideal substrate for the growth of superconductive $h\text{\ensuremath{-}}{\mathrm{MnB}}_{3}$. The unique superconducting mechanism observed here could inspire the searching of more boron kagome based two-dimensional superconductors.

Uranus and Neptune are generally assumed to have helium only in their gaseous atmospheres. Here, we report the possibility of helium being fixed in the upper mantles of these planets in the form of NH3–He compounds. Structure predictions reveal two energetically stable NH3–He compounds with stoichiometries (NH3)2He and NH3He at high pressures. At low temperatures, (NH3)2He is ionic with NH3 molecules partially dissociating into (NH2)− and (NH4)+ ions. Simulations show that (NH3)2He transforms into intermediate phase at 100 GPa and 1000 K with H atoms slightly vibrate around N atoms, and then to a superionic phase at ~2000 K with H and He exhibiting liquid behavior within the fixed N sublattice. Finally, (NH3)2He becomes a fluid phase at temperatures of 3000 K. The stability of (NH3)2He at high pressure and temperature could contribute to update models of the interiors of Uranus and Neptune., Helium is generally considered too inert to be present in giant ice planet mantles. The authors, by first-principles calculations and crystal structure searches, find stable ammonia–helium compounds at the conditions of Uranus and Neptune’s upper mantles, with possible implications in the planet composition models.

Crystalline silicon is dominating the current solar cell market due to the significant efficiency improvement and cost reduction in last decades. However, its indirect band gap nature leads to inefficient visible-light absorption, which seriously impedes further performance enhancement in silicon-based photovoltaic devices. Thus, it is highly desirable to develop direct band gap silicon materials. Herein, by means of ab initio swarm-intelligence structure-searching method, we predicted a quasi-direct gap semiconducting tri-layer silicene structure consisting of alternating arrays of six-membered Si rings, which can be converted into a direct gap semiconductor of 0.86 eV by applying a low tensile strain (~ 2.5%). Our calculations revealed that the photovoltaic efficiency of the tri-layer silicene reaches 29% at 1.0 µm, which is comparable to that of bulk GaAs with the highest conversion efficiency among thin-film solar cell absorbers.

The corrosion behavior of a high manganese steel in simulated marine splash zone environment was studied by dry-wet cyclic corrosion experiment and electrochemical experiment. Corrosion kinetics, composition, surface morphology, cross-section morphology, element distribution, valence state, polarization curve and electrochemical impedance spectroscopy were analyzed with the aim of characterizing the characteristics of corrosion product films. The results show that in chloride-containing environment, in the initial corrosion products, Mn oxides with porous structure lead to higher corrosion rate. As corrosion extends, the formation of alloy element oxides in corrosion products changes the corrosion properties of rust layers at different stages. Mo oxides form a stable passivation film, which reduces the influence of chloride ion on corrosion. Ni oxides in the inner rust layer facilitate the transformation of goethite, and Cr oxides in the outer rust layer increase the densification of the rust layer. The stability and compactness of Fe3O4, α-FeOOH and FeCr2O4 in the later corrosion products inhibit the corrosion action of manganese iron oxides and slow down the corrosion rate. With the corrosion durations, the corrosion current density of the sample with the corrosion product film first increases and then decreases, and the corrosion potential first moves negative and then shifts in a positive direction subsequently, indicating that the protective effect of the corrosion product film is gradually significant.

Whether quality can be improved and style characteristics of different types of tobaccos can be changed after being cured using different methods has not been clear yet. It is necessary to explore the influences of different curing methods on chemical compositions of different types of tobaccos. For this purpose, by taking flue-cured tobacco K326, burley tobacco Yunbai 3 and oriental tobacco Basma 14 as materials, the effects of air-curing, sun-curing and flue-curing methods on chemical compositions of these three types of tobaccos were investigated by taking the freeze-dried tobacco as the control group based on the equilibrium method of matter loss. The results show that compared with freeze-dried tobacco, (1) The air-cured, flue-cured and sun-cured were displayed in a descending order in terms of the dry matter loss and dry matter loss rate of K326, burley and oriental tobaccos thereby. (2) After performing air-cured, sun-cured and flue-cured, the starch contents in the oriental and flue-cured tobaccos greatly reduce while their contents of the total sugar and reducing sugar rose; the contents of starch and reducing sugar in the burley tobacco both decreased. (3) The contents of protein, total nitrogen and nicotine in the three types of air-cured, sun-cured and flue-cured tobaccos all significantly decreased. (4) The reduction amounts of the pigment content in the sun-dried burley and flue-cured tobaccos were the largest while that in the flue-cured oriental tobacco reaches the largest. (5) The total polyphenol contents in the three types of tobaccos all significantly reduced after being air-cured, sun-cured and flue-cured. The total polyphenol contents in the flue-cured and burley tobaccos were significantly larger than those in air-cured and sun-cured ones; the total polyphenol content in the sun-cured oriental tobacco was significantly larger than those in the groups treated with other curing methods. (6) The potassium (K) and chlorine (Cl) contents in the three types of tobaccos processed by the other curing methods were relatively stable. (7) The sensory evaluation scores of flue-cured tobaccos, burley tobacco and oriental tobacco were higher after flue-cured based on Yunnan sensory evaluation method. The study clarifies the transformation law of chemical compositions in different types of tobaccos under different curing methods. A type of tobaccos is not only limited to single curing method. It is feasible to combine multiple curing methods to enrich the style characteristics of tobaccos.

Microplastics were reported to adsorb antibiotics and may modify their effects on soil systems. But there has been little research investigating how microplastics may affect the toxicities of antibiotics to microbes under future climate conditions. Here, we used a free-air CO2 enrichment system to investigate the responses of soil microbes to sulfamethazine (SMZ, 1 mg kg−1) in the presence of polystyrene microplastics (PS, 5 mg kg−1) at different CO2 concentrations (ambient at 380 ppm and elevated at 580 ppm). SMZ alone decreased bacterial diversity, negatively affected the bacterial structure and inter-relationships, and enriched the sulfonamide-resistance genes (sul1 and sul2) and class 1 integron (intl1). PS, at both CO2 conditions, showed little effect on soil bacteria but markedly alleviated SMZ’s adverse effects on bacterial diversity, composition and structure, and inhibited sul1 transmission by decreasing the intl1 abundance. Elevated CO2 had limited modification in SMZ’s disadvantages to microbial communities but markedly decreased the sul1 and sul2 abundance. Results indicated that increasing CO2 concentration or the presence of PS affected the responses of soil microbes to SMZ, providing new insights into the risk prediction of antibiotics under future climate conditions.

The influences of two red mud (RM) samples (ZZ and ZM) on fusion behaviors of three high ash fusion temperature (AFT) coals (FZ, JC and JZ) were investigated. It was evaluated by determining AFTs of coals, RMs, and the mixtures of coal ash with RM, as well as their compositions of ashes and mineral. The results showed that the contents of CaO, Fe2O3, and Na2O in RMs were higher than those in coal ashes, which caused RMs’ AFTs lower than those of coals. The formation of high melting-point mullite might be the main factor causing coal AFTs higher. With the increase in RM mass ratio, the increasing amount of low-melting eutectic (anorthite (CaAl2Si2O8), fayalite (Fe2SiO4), and anorthite (Na-rich) (Ca,Na)(Si,Al)4O8)) and amorphous matter made AFTs lower. ZZ reduced AFTs obviously than ZM because the content of Na2O in ZZ was higher than that in ZM. Owing to lower ion potential of Na+ than those of Ca2+ and Fe2+, Na+ is easier to enter into the lattice of mullite and results in the reduction of AFTs.

Titanium dioxide has been widely used as an efficient transition metal oxide photocatalyst. However, its photocatalytic activity is limited to the ultraviolet spectrum range due to the large bandgap beyond 3 eV. Efforts to reduce the bandgap to achieve a broader spectrum range of light absorption have been successfully attempted via the experimental synthesis of dopant-free metastable surface structures of rutile-type TiO2 (011) 2 × 1. This new surface phase possesses a reduced bandgap of ∼2.1 eV, showing great potential for an excellent photocatalyst covering a wide range of visible light. There is a need to establish the atomistic structure of this metastable surface to understand the physical cause for the bandgap reduction and to improve the future design of photocatalysts. Here, we report computational investigations in an effort to unravel this surface structure via swarm structure-searching simulations. The established structure adopts the anatase (101)-like structure model, where the topmost 2-fol...

The ash adhesion and deposition (AD)characteristics of three low-rank coal (LRC) were investigated by self-made AD analyzer, X-ray fluorescence spectrometry, scanning electron microscopy equipped with energy dispersive X-ray detector, and X-ray diffraction. Under a given condition, the deposition mass ratios of different LRC ashes are different, which mainly due to the difference in iron content. The mass ratios of ash deposition under oxidizing atmospheres are higher than those under reducing atmospheres because of the effects of different valence of iron. The mass ratio of AD increases with the increase of temperature, while it decreases with gas velocity increases. The possible formation mechanism of AD is proposed by adhesive amorphous matter formation, iron enrichment and the generation of ferro-aluminate and ferro-alumino silicate, substitution of Fe 2 + by Ca 2 + , and mullite adhesion.

Pentalenolactone is a microbial sesquiterpenoid with antibiotic activity. Its biosynthetic pathway was elucidated by a combination of genetic and biochemical characterizations of all genes involved. For the related neopentalenoketolactone biosynthetic gene cluster from Streptomyces avermitilis, an α-ketoglutarate-dependent mononuclear nonheme iron enzyme, PtlD, was proposed to catalyze both desaturation and olefin epoxidation reactions. Yet, these activities remained to be validated by in vitro biochemical evidence. In this report, we demonstrated that PtlD has multiple activities, including hydroxylation, desaturation, and epoxidation, and confirmed the presence of the elusive epoxide intermediate in a neopentalenoketolactone pathway.

Titanium dioxide has been widely used in modern industrial applications, especially as an effective photocatalyst. Recently, freestanding TiO2 films with a markedly reduced bandgap of ∼1.8 eV have been synthesized, indicating that the dimension has a considerable influence on the bulk band gap (>∼3 eV) and enhances the adsorption range of visible light. Titanium oxide compounds have various stoichiometries and versatile properties. Therefore, it is very necessary to explore the electronic properties and functionalities of other titanium oxide films with different stoichiometries. Here, we combined structure searches with first-principle calculations to explore candidate Ti–O films with different stoichiometries. In addition to the experimentally synthesized TiO2 film, the structure searches identified three new energetically and dynamically stable Ti–O films with stoichiometries of Ti3O5, Ti3O2, and Ti2O. Calculations show that the Ti–O films undergo several interesting electronic transformations as the Ti fraction increases, namely, from a wide-gap semiconductor (TiO2, 3.2 eV) to a narrow-gap semiconductor (Ti3O5, 1.80 eV) and then to metals (Ti3O2 and Ti2O) due to the abundance of unpaired Ti_d electrons. In addition to the electronic transformations, we observed nonmagnetic (TiO2) to ferromagnetic (Ti3O5, Ti3O2, and Ti2O) transformations. Notably, the Ti3O5 film possesses both narrow-gap semiconductive and ferromagnetic properties, with a large magnetic moment of 2.0 µB per unit cell; therefore, this film has high potential for use in applications such as spintronic devices. The results highlight metal fraction-induced electronic and magnetic transformations in transition metal oxide films and provide an alternative route for the design of new, functional thin-film materials.Titanium dioxide has been widely used in modern industrial applications, especially as an effective photocatalyst. Recently, freestanding TiO2 films with a markedly reduced bandgap of ∼1.8 eV have been synthesized, indicating that the dimension has a considerable influence on the bulk band gap (>∼3 eV) and enhances the adsorption range of visible light. Titanium oxide compounds have various stoichiometries and versatile properties. Therefore, it is very necessary to explore the electronic properties and functionalities of other titanium oxide films with different stoichiometries. Here, we combined structure searches with first-principle calculations to explore candidate Ti–O films with different stoichiometries. In addition to the experimentally synthesized TiO2 film, the structure searches identified three new energetically and dynamically stable Ti–O films with stoichiometries of Ti3O5, Ti3O2, and Ti2O. Calculations show that the Ti–O films undergo several interesting electronic transformations as the T...

The search for new inorganic electrides has attracted significant attention due to their potential applications in transparent conductors, battery electrodes, electron emitters, as well as catalysts for chemical synthesis. However, only a few inorganic electrides have been successfully synthesized thus far, limiting the variety of electride examples. Here, we show the stabilization of inorganic electrides in the Ti-rich Ti–O system through first-principles calculations in conjunction with swarm-intelligence-based CALYPSO method for structure prediction. Besides the known Ti-rich stoichiometries of Ti2O, Ti3O, and Ti6O, two hitherto unknown Ti4O and Ti5O stoichiometries are predicted to be thermodynamically stable at certain pressure conditions. We found that these Ti-rich Ti–O compounds are primarily zero-dimensional electrides with excess electrons confined in the atom-sized lattice voids or between the cationic layers playing the role as anions. The underlying mechanism behind the stabilization of electrides has been rationalized in terms of the excess electrons provided by Ti atoms and their accommodation of excess electrons by multiple cavities and layered atomic packings. The present results provide a viable direction for searching for practical electrides in the technically important Ti–O system. Computer simulations predict that compounds made of oxygen and titanium atoms form cages that can host electrons in their interstices. A team led by Hanyu Liu and Yanming Ma from Jilin University, China, have investigated the possibility for materials belonging to the family of titanium dioxide, a pigment used in paints and sunscreens, to behave as electrides, materials in which electrons resemble larger negatively charged atoms in the way in which they localize and interact with the surrounding atomic structure. Their calculations show that this occurs if the amount of titanium atoms in the material exceeds that of oxygen atoms by at least a factor of 2, which allows the formation of larger cages in which electrons can be confined. The synthesis of these materials will allow to assess their significance for catalysis or other applications.

Background Drug resistance in clinical cancer treatment has become an issue. Objective We focus on abnormally expressed lncRNAs in glioma and investigating the function of PVT1. Methods The paclitaxel-resistant glioma cells SHG-44 RE was obtained through screening the SHG 44 cells that were cultured in medium containing a certain concentration of paclitaxel. Cell survival of SHG 44 RE and SHG 44 cells under the treatment of paclitaxel was detected by MTT assay. The aberrant expressed lncRNAs were screened out with microarray analysis. Further qRT-PCR was utilized to validate the expression of lncRNA PVT1 in the two cells. After manipulating the expression of PVT1, cell viability and apoptosis were measured by MTT and flow cytometry respectively. Results LncRNA PVT1 was overexpressed in glioma cells SHG-44 RE compared with parent SHG-44 cells. Down-regulation of lncRNA PVT1 inhibited the SHG-44 RE cell viability and increased glioma SHG-44 RE cells apoptosis after paclitaxel treatment, suggesting that inhibition of lncRNA PVT1 improved paclitaxel sensibility in human glioma cells. Conclusion Down-regulation of PVT1 could enhance chemosensitivity of paclitaxel, induce apoptosis of glioma cells and noteworthy inhibit glioma cells proliferation. Our findings of PVT1 could contribute to attenuate paclitaxel resistance in clinical medicine.

Antibiotic resistance and rising CO2 levels are considered among the most significant challenges we will face in terms of global development over the following decades. However, the impact of elevated CO2 on soil antibiotic resistance has rarely been investigated. We used a free-air CO2 enrichment system to investigate the potential risks posed by applying mineral and organic fertilizers to paddy soil at current CO2 concentration (370 ppm) and future elevated CO2 (eCO2, 570 ppm predicted for 2100). Organic fertilizer substitution (substituting the mineral fertilizer by 50% N) alone increased the plant uptake and soil residue of sulfamethazine, and enriched sulfonamide resistance genes (sul1, sul2), tetracycline resistance genes (tetG, tetM) and class 1 integron (intl1). But it decreased the rice grain yield (by 7.6%). Comparatively, eCO2 decreased the sul2, tetG and intl1 gene abundances by organic fertilizer substitution, and meanwhile increased grain yield (by 8.4%). Proteobacteria and Nitrospirae were potential hosts of antibiotic resistance genes (ARGs). Horizontal gene transfer via intl1 may play an important role in ARGs spread under eCO2. Results indicated that future elevated CO2 concentration could modify the effects of organic fertilizer substitution on rice yield and soil ARGs, with unknown implications for future medicine and human health.

Nitrogen (N)-doped graphitic carbons with one-dimensional hollow/porous structures were synthesized via a sacrificial template of CdTe@ZIF-8 nanofibers. The N-doped graphitic carbons exhibited better electrocatalytic activity for ORR based on higher diffusion-limited current density and more positive half-wave potential as compared to carbons derived from ZIF-8.

Artificially polluted surface water was treated using magnetic-seeding coagulation, with polyaluminum chloride (PAC) as the coagulant and a ferromagnetic material as the magnetic seed (MS). A novel approach using a combination of response surface methodology (RSM) and the Box–Behnken design (BBD) was employed to evaluate the effects and interactions of four main factors, the dosages and dosing points of PAC and MS. The three response variables selected to evaluate the effectiveness of the treatment were supernatant turbidity removal rate, floc size, and floc strength. The optimal operating conditions were obtained by constraining the three desirable responses using Minitab software. The PAC and MS dosages (22.7 mg/L and 0.6 g/L) and their dosing points (1.5 and 1.2 min) were determined to be the optimum conditions for the maximum turbidity removal rate, floc size, and floc strength of 98.0%, 154.7 μm, and 57.8%, respectively. Confirmation experiments demonstrated that such a combination of RSM and...

Catalytically active graphene-based hollow TiO2 composites(TiO2/RGO) were successfully synthesized via the solvothermal method. Hollow TiO2 microspheres are uniformly dispersed on RGO. X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) were used for the characterization of prepared photocatalysts. The mass of GO was optimized in the photocatalytic removal of rhodamine B (RhB) as a model dye pollutants. The results showed that graphene-based hollow TiO2 composites exhibit a significantly enhanced photocatalytic activity in degradation of RhB under either UV or visible light irradiation. The formation of the graphene-based hollow TiO2 composites and the photocatalytic mechanisms under UV and visible light were also discussed.

The fusion characteristics of three low-rank coals and cornstalk (CS) mixtures were investigated by ash fusion temperature (AFT) analysis, X-ray fluorescence spectrometry, scanning electron microscopy, and X-ray diffractometry. The increasing trend of CS ash fusion temperature (AFT) is not the same with the additions of different coals at the same mass ratio, due to the difference of the ash content and component of coal samples. Variations in AFTs depended on the mineral composition, which derived from mineral interaction. As the coal mass ratio increased at high temperature, Ca 2+ replaced K + in semi-molten alumino-silicate in CS ashes and led to formation of higher-melting-point anorthite, which also increased the AFT of the ash mixture. The AFT fluctuation of CS/Husheng lignite (HS) mixture during addition of HS resulted from formation of higher-MP mullite.

Pyropia yezoensis can survive the severe water loss that occurs during low tide, making it an ideal species to investigate the acclimation mechanism of intertidal seaweed to special extreme environments. In this study, we determined the effects of high salinity on photosynthesis using increasing salinity around algal tissues. Both electron transport rates, ETR (I) and ETR (II), showed continuous decreases as the salinity increased. However, the difference between these factors remained relatively stable, similar to the control. Inhibitor experiments illustrated that there were at least three different cyclic electron transport pathways. Under conditions of severe salinity, NAD(P)H could be exploited as an endogenous electron donor to reduce the plastoquinone pool in Py. yezoensis. Based on these findings, we next examined how these different cyclic electron transport (CETs) pathways were coordinated by cloning the gene (HM370553) for ferredoxin-NADP+ oxidoreductase (FNR). A phylogenetic tree was constructed, and the evolutionary relationships among different FNRs were evaluated. The results indicated that the Py. yezoensis FNR showed a closer relationship with cyanobacterial FNR. The results of both real-time polymerase chain reaction and western blotting showed that the enzyme was upregulated under 90–120‰ salinity. Due to the structure-function correlations in organism, Py. yezoensis FNR was proposed to be involved in NAD(P)H-dependent Fd+ reduction under severe salinity conditions. Thus, through the connection between different donors bridged by FNR, electrons were channeled toward distinct routes according to the different metabolic demands. This was expected to make the electron transfer in the chloroplasts become more flexible and to contribute greatly to acclimation of Py. yezoensis to the extreme variable environments in the intertidal zone.

As one of the most abundant elements on earth, sulfur is part of many small molecular metabolites and is key to their biological activities. Over the past few decades, some general strategies have been discovered for the incorporation of sulfur into natural products. In this review, we summarize recent efforts in elucidating the biosynthetic details for two sulfur-containing metabolites, ergothioneine and ovothiol. Their biosyntheses involve an unprecedented trans-sulfur strategy, a combination of a mononuclear non-heme iron enzyme-catalyzed oxidative C–S bond formation reaction and a PLP enzyme-mediated C–S lyase reaction.

In this study, hollow core/shell CeO2@TiO2 photocatalysts were prepared via precipitation-co-hydrothermal method. X-ray diffraction, transmission electron microscopy, UV−Vis diffuse reflectance spectroscopy, thermo-gravimetric–differential thermal analysis, and photoluminescence were used for the characterization of prepared photocatalysts. The synthesis variables were optimized in the photocatalytic removal of rhodamine B (rhB) as a model dye pollutants. The results showed that hollow core/shell CeO2@TiO2 exhibit a significantly enhanced photocatalytic activity in degradation of rhB under either UV or visible light irradiation. The formation of the hollow core/shell CeO2@TiO2 and the photocatalytic mechanisms under UV and visible light were also discussed.

An anatase TiO2(001) surface has shown great potential as an ideal and powerful photocatalyst due to its chemical stability, nontoxicity, and high reactivity. However, the fundamental atomic structure of the reconstructed anatase (001)-(1 × 4) surface is still under debate, which greatly impedes further exploration of its chemical activity. Herein, the anatase (001)-(1 × 4) surface reconstruction and the photocatalytic reactivity have been extensively studied using an effective surface structure searching method in combination with the first-principles calculations. Our study reveals that there exist two stable (1 × 4) reconstructed surfaces, i.e., the previously proposed "ad-molecule" (ADM) and oxidized ridge (OR) surface structures, and their simulated STM images are in good agreement with experimental observations. Moreover, we find that the ADM surface has superior photocatalytic reactivity to the OR surface and a small number of water can be dissociated at the terrace at one water monolayer coverage, which has never been found before. These findings can not only be applied to solve the experimental controversies about the atomic structure of the reconstructed anatase (001)-(1 × 4) surface but also provide a theoretical basis for exploring the intrinsic properties of the surface.

In the presence of sulfonated polystyrene (sPS) template, sPS@SnO 2 core shell particles formed via the interaction between the functional group of -SO 3 H on the template surface and ions of Sn 2+ from the precursor of SnSO 4 which were in ethanol-aqueous medium. After high-temperature calcination treatment for removal of sPS, the sPS@SnO 2 changed into SnO 2 hollow spheres. With the further carbonization of the sPS@SnO 2 @glucose composite microspheres, SnO 2 @C composite hollow spheres were fabricated. Using SEM, TEM, and N 2 adsorption - desorption technology, the structure, specific surface area, and the core-shell structure formation mechanism were determined. Cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) properties of SnO 2 hollow spheres and SnO 2 @C composites were investigated, respectively, in the foam nickel electrode under alkaline condition. The specific capacitance of SnO 2 @C composite hollow spheres could reach 25.8 F g −1 in 1 mol L −1 KOH aqueous solution and showed excellent charge-discharge behavior.

Hollow SnO2 microspheres are prepared from resorcinol–formaldehyde gel and different tin compound precursors, including stannous sulfate (SnSO4), stannous chloride dihydrate (SnCl2·2H2O), and stannic chloride pentahydrate (SnCl4·5H2O) via chemically induced self-assembly in hydrothermal environment. Morphological and structural characterizations of as-prepared hollow SnO2 microspheres are carried out using scanning electron microscopy, X-ray diffraction, and nitrogen adsorption–desorption method. Their electrochemical properties as the supercapacitor electrode materials for application are also investigated using cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) measurement in 1 M H2SO4 electrolyte. There are redox peaks in CV curves and a large number of Faradic plateaus in GCD curves. At different scan rates, all the obtained samples have excellent electrochemical properties. The hollow SnO2 microspheres obtained from SnSO4 and SnCl2·2H2O as precursors show relatively lower specific capacitances of 395 and 347 F g−1, respectively. However, the specific capacitance of SnO2 from SnCl4·5H2O is up to 663 F g−1. The high specific surface area and hollow structure of SnO2 microspheres are due to facilitating the rapid transport of electrolyte ions and improving the electrochemical performance. It is expected that hollow SnO2 microspheres are the promising redox supercapacitor materials.

A robust and sensitive high performance liquid chromatography-electrospray tandem mass spectrometry (HPLC-ESI MS/MS) method was developed with solid phase extraction (SPE) sample preparation. It was optimized for the analysis of various amino acids in rat plasma. Silica-based strong cationic exchange SPE cartridges were used to extract amino acids and minimize the ion-suppression effect. The SPE cleanup protocol was optimized and it was found that the sample loading pH was very critical for the recovery and reproducibility. When the plasma sample was mixed with 0.1 mol/L acetic acid (pH 2.8) and loaded on SPE cartridge, the recoveries and repeatability for most of the amino acids were satisfactory. The method was fully validated. The analytical characteristics such as total recoveries (33.6%-107.7%, except lysine and ornithine), linearities (r > 0.99 except arginine), intra-day precisions (relative standard deviation (RSD) < 9.0%) and inter-day precisions (RSD < 19.1%) were satisfactory for most of the amino acids. Furthermore, the method was successfully applied to study the ionizing radiation exposure induced changes in amino acid concentration of plasma samples from rats. Experimental results showed that the ionization radiation could lead to metabolism disorder of plasma amino acids, and the degree of disorder was related with the degree of injury by the ionization radiation injury. Some of the amino acids may be potential biomarkers of ionization radiation injury. These results provide experimental basis for screening of new markers of the acute radiation damage.

Two polymorphs of 3,4-bis(2-benzimidazolyl)pyridine (1) were prepared and characterized by infrared, nuclear magnetic resonance spectroscopy and single-crystal X-ray crystallography. The metastable greenish polymorph 1a (hexagonal space group P6522) was solvothermally formed first, which can be irreversibly transformed into the stable yellow polymorph 1b (orthorhombic space group Pbcn) on heating or recrystallization. The structure of 1a shows a dihedral angle of 45.3° between the benzimidazolyl/pyridyl rings and a dihedral angle of 52.2° between the benzimidazolyl/benzimidazolyl rings, while the corresponding dihedral angles in the structure of 1b are 48.0° and 67.9°, respectively. The two polymorphs exhibit different combination of intermolecular interactions (N–H⋯N hydrogen bonds, π–π stacking or C–H⋯π interaction), leading to significantly different supramolecular assemblies. The photophysical properties of 1a and 1b have also been studied.

The reaction of o-carboranyllithium with two equiv. of 2-pyridinecarboxaldehyde affords 1-[(hydroxy)(pyridyl)methyl]-o-carborane (1) and 1,2-bis[(hydroxy)(pyridyl)methyl]-o-carborane (2), which have been characterized by IR and NMR spectroscopy, mass spectrometry and single-crystal X-ray diffraction. Compound 2 exhibits interesting polymorphism (monoclinic 2a and triclinic 2b). The solid state structures of the new carboranes feature intermolecular and intramolecular hydrogen bonding interactions involving all the N and O atoms, leading to one dimensional (1, 2b) or two-dimensional (2a) supramolecular structures. The photoluminescence of 1 and 2b was investigated in the solid and solution states at room temperature, respectively.

In this study, a method is developed to fabricate sulfonated poly (ether ether ketone)/phosphotungstic acid-polyaniline (SPEEK/HPW-PANI) membranes by in situ polymerization of aniline for the purpose of decreasing the weight loss of HPW in the membranes. The synthesis involves the production of a SPEEK/HPW hybrid membrane followed by different layer of PANI coatings on the membrane surface, and subsequent treatment using drying in vacuum procedures. The scanning electronic microscopy images showed that HPW had good compatibility with SPEEK polymers and energy dispersive X-ray spectroscopy revealed the successfully doping with HPW and polymerization of PANI. The surface of SPEEK/HPW-PANI becomes more compact than that of SPEEK/HPW and pure SPEEK, which may lead to reduce the water uptake and swelling property. The proton conductivity was found for the SPEEK/HPW-PANI-5 composite membrane (91.53 mS/cm at 80°C) higher than that of pure SPEEK membrane (68.72 mS/cm at 80°C). Better thermal stability was determined in both SPEEK/HPW and SPEEK/HPW-PANI membranes than pristine SPEEK membrane. Therefore, PANI is a good potential coating for organic–inorganic hybrid e.g. SPEEK/HPW membrane materials to improve their hydrothermal stable properties and SPEEK/HPW PANI is a material that shows promise as a proton exchange membranes. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41033.

A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/ MS) method was established for the determination of inabenfide in fruits, vegetables, tea, honey, cereals and animal-derived foods. The food samples were extracted with acetonitrile, then purified by dispersion solid phase extraction using primary secondary amine (PSA) and C18 as solid phase. The residue was determined and confirmed by HPLC-MS/MS and quantified by external standard method. The mass spectrometric detection was operated with electrospray in positive ionization mode and inabenfide was identified in multiple reaction monitoring (MRM) mode. The interference of matrix was reduced by the matrix-matched calibration standard curves. The linear range of the method was 1 - 100 microg/kg, with the correlation coefficients (r2) of 0.998 - 0.999. The recoveries of inabenfide spiked in food samples were 85.2% - 112.4% at the spiked levels of 5, 10, 50 microg/kg. The relative standard deviations (RSDs) were less than 8.5%. The limits of detection (LODs) were 0.08 - 1.64 microg/kg, and the limits of quantification (LOQs) were 0.30 - 5.48 microg/kg. The results showed that the proposed method is sensitive and accurate for the determination of inabenfide in foodstuffs.

The reaction of dithio-o-carborane with diphenyldiselenide (PhSeSePh) affords the title compound, closo-1,2-(PhSe)2C2B10H10 (1), which has been characterized by IR and NMR (1H, 11B) spectroscopy and by single-crystal X-ray diffraction. The phenylselenyl groups are bonded to the cage carbon atoms of the o-carborane cluster with a Ccage-Ccage distance of 1.751(6) Å and an Se-Ccage- Ccage-Se torsion angle of 10.1(3)°. Compound 1 displays a violet emission on excitation with UV light. For comparison the photoluminescence of the known analog closo-1,2-(PhS)2C2B10H10 (2) was also studied

The reactions of the dithiolato-o-carborane salt (Et3NH)2(S2C2B10H10) (2) with alkyl halides BrCH2CH=CH2, BrCH2CH2CH2Cl and C6H5CH2Cl, afford the o-carboranyl-bisthioether derivatives 3a - c, which have been characterized by IR and NMR (1H, 13C, 11B) spectroscopy, mass spectrometry, and single-crystal X-ray diffraction (3c). The photoluminescent properties of the known compound 3c has been investigated. It exhibits a violet (chloroform solution) or blue (solid state) emission when excited with UV light.