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A large gap two-dimensional (2D)topological insulator (TI), also known as a quantum spin Hall (QSH)insulator, is highly desirable for low-power-consuming electronicdevices owing to its spin-polarized backscattering-free edge conductingchannels. Although many freestanding films have been predicted to harbor the QSH phase, band topologyof a film can be modified substantially when it is placed or grownon a substrate, making the materials realization of a 2D TI challenging.Here we report a first-principles study of possible QSH phases in75 binary combinations of group III (B, Al, Ga, In, and Tl) and groupV (N, P, As, Sb, and Bi) elements in the 2D buckled honeycomb structure,including hydrogenation on one or both sides of the films to simulatesubstrate effects. A total of six compounds (GaBi, InBi, TlBi, TlAs,TlSb, and TlN) are identified to be nontrivial in unhydrogenated case;whereas for hydrogenated case, only four (GaBi, InBi, TlBi, and TlSb)remains nontrivial. The band gap is found to be as large as 855 meVfor the hydrogenated TlBi film, making this class of III–Vmaterials suitable for room temperature applications. TlBi remainstopologically nontrivial with a large band gap at various hydrogencoverages, indicating the robustness of its band topology againstbonding effects of substrates. [ABSTRACT FROM AUTHOR]

We use first-principles electronicstructure calculations to predicta new class of two-dimensional (2D) topological insulators (TIs) inbinary compositions of group III elements (B, Al, Ga, In, and Tl)and bismuth (Bi) in a buckled honeycomb structure. We identify bandinversions in pristine GaBi, InBi, and TlBi bilayers, with gaps aslarge as 560 meV, making these materials suitable for room-temperatureapplications. Furthermore, we demonstrate the possibility of strainengineering in that the topological phase transition in BBi and AlBicould be driven at ∼6.6% strain. The buckled structure allowsthe formation of two different topological edge states in the zigzagand armchair edges. More importantly, isolated Dirac-cone edge statesare predicted for armchair edges with the Dirac point lying in themiddle of the 2D bulk gap. A room-temperature bulk band gap and anisolated Dirac cone allow these states to reach the long-sought topologicalspin-transport regime. Our findings suggest that the buckled honeycombstructure is a versatile platform for hosting nontrivial topologicalstates and spin-polarized Dirac fermions with the flexibility of chemicaland mechanical tunability. [ABSTRACT FROM AUTHOR]

Developing aggregation-induced emission (AIE)-based hydrogels that exhibit fluorescence enhancement as to thermal properties is an interesting and challenging task. In this work, we employed the fluorophore 2'-hydroxychalcone (HC), fluorescence properties of which are easily influenced by the excited-state intramolecular proton transfer and twisted intramolecular charge transfer (TICT) effects, to develop a novel type of temperature-sensitive polymers, hydroxychalcone-based polymers (HCPs). By controlling the temperature-dependent water microenvironments in HCPs, the intramolecular hydrogen bonds between water and HCPs can be regulated, thereby influencing the TICT process and leading to thermo-induced fluorescence enhancement, which shows a contrary tendency compared to typical AIEgens that always exhibit fluorescence attenuation as the thermal energy accelerates the molecular motion. Following the decoration with triphenylphosphine, the resulting polymer P-HCP assembled into nanohydrogels and served as a fluorescent probe for intracellular mitochondrial temperature sensing.

Wastewater ozonation forms various toxic byproducts, such as aldehydes, bromate, and organic bromine. However, there is currently no clear understanding of the overall toxicity changes in ozonated wastewater because pretreatment with solid phase extraction cannot retain inorganic bromate and volatile aldehydes, yet contributions of known ozonation byproducts to toxicity are unknown. Moreover, compared with bromate, organic bromine did not receive widespread attention. This study evaluated the toxicity of ozonated wastewater by taking aldehydes, bromate, and organic bromine into consideration. In the absence of bromide, formaldehyde contributed 96-97% cytotoxicity and 92-95% genotoxicity to HepG2 cells among the detected known byproducts, while acetaldehyde, propionaldehyde, and glyoxal had little toxicity. Both formaldehyde and dibromoacetonitrile drove toxicity among the known byproducts when bromide was present. Toxicity assays in HepG2 cells showed that when secondary effluents contained no bromide, the cytotoxicity of the nonvolatile organic fraction (NVOF) was reduced by 56-70%, and genotoxicity was completely removed after ozonation. However, the formed aldehydes (volatile organic fraction, VOF) led to increased overall toxicity. In the presence of bromide, compared with the secondary effluent, ozonation increased the cytotoxicity of the NVOF Br from 3.4-4.0 mg phenol/L to 10.3-13.9 mg phenol/L, possibly due to the formation of organic bromine. In addition, considering the toxicity of VOF Br (VOF in the presence of bromide, including aldehydes, tribromomethane, etc.), the overall cytotoxicity and genotoxicity became much higher than those of the secondary effluent. Although bromate had a limited impact on cytotoxicity and genotoxicity, it caused an increase in oxidative stress in HepG2 cells. Therefore, when taking full account of nonvolatile, volatile, and inorganic fractions, ozonation generally increases the toxicity of wastewater.

Major depressive disorder (MDD) is a severe psychiatric disease that has critically affected life quality for millions of people. Chronic stress is gradually recognized as a primary pathogenesis risk factor of MDD. Despite the remarkable progress in mechanism research, the pathogenesis mechanism of MDD is still not well understood. Therefore, we conducted a liquid chromatography-tandem mass spectrometry (LC-MS/MS) detection of 25 major metabolites of tryptophanic, GABAergic, and catecholaminergic pathways in the prefontal cortex (PFC) of mice in chronic social defeat stress (CSDS). The depressed mice exhibit significant reduction of glutamate in the GABAergic pathway and an increase of L-DOPA and vanillylmandelic acid in catecholaminergic pathways. The data of real-time-quantitative polymerase chain reaction (RT-qPCR) and Western blotting analysis revealed an altered level of glutamatergic circuitry. The metabolomic and molecular data reveal that the glutamatergic disorder in mice shed lights to reveal a mechanism on depression-like and stress resilient phenotype.

A large gap two-dimensional (2D) topological insulator (TI), also known as a quantum spin Hall (QSH) insulator, is highly desirable for low-power-consuming electronic devices owing to its spin-polarized backscattering-free edge conducting channels. Although many freestanding films have been predicted to harbor the QSH phase, band topology of a film can be modified substantially when it is placed or grown on a substrate, making the materials realization of a 2D TI challenging. Here we report a first-principles study of possible QSH phases in 75 binary combinations of group III (B, Al, Ga, In, and Tl) and group V (N, P, As, Sb, and Bi) elements in the 2D buckled honeycomb structure, including hydrogenation on one or both sides of the films to simulate substrate effects. A total of six compounds (GaBi, InBi, TlBi, TlAs, TlSb, and TlN) are identified to be nontrivial in unhydrogenated case; whereas for hydrogenated case, only four (GaBi, InBi, TlBi, and TlSb) remains nontrivial. The band gap is found to be as large as 855 meV for the hydrogenated TlBi film, making this class of III-V materials suitable for room temperature applications. TlBi remains topologically nontrivial with a large band gap at various hydrogen coverages, indicating the robustness of its band topology against bonding effects of substrates.

A novel class of aminoisonucleoside was synthesized and incorporated into a luciferase gene-targeting siRNA. Structural and functional analyses of such a kind of siRNAs indicated that sense strand modifications with aminoisonucleoside at the 3' or 5' terminal, such as ssIso-1 and ssIso-2, have less effect on RNA duplex thermal and serum stabilities, and their functional activities are also comparable to their native siRNAs. In contrast, antisense strand modifications with aminoisonucleoside at the corresponding positions, such as asIso-2 or asIso-1, bring a striking negative effect on RNA duplex stability but still maintain around 40-50% of gene knockdown.