Synthesis and antimicrobial bioassays of 1,3,4-thiadiazole sulfone derivatives containing amide moiety: A study based on molecular dynamics (MD) simulations,MM/GBSA,and molecular docking

The backbone structure (1,3,4-thiadiazole sulfone derivatives containing amide moiety) of target compounds was determined by modification and optimization of the theoretical design based on commercial chemical carboxin, including molecular docking, scaffold hopping, ligand expansion, etc.In this paper, 23 target compounds were synthesized by the combination of theoretical design and chemical synthesis, and characterized by ¹H NMR, ¹³C NMR and HR MS. Addtionally, the antibacterical bioassay showed that most target compounds performed excellent inhibition on Xanthomonas axonopodis pv. citri (Xac) and Xanthomonas oryzae pv. oryzae (Xoo) in vitro. Meanwhile, molecular docking, molecular dynamics (MD) simulations, and studies on ligand/protein (carboxin/2FBW and 4n/2FBW) complex systems were displayed, and the interaction patterns of ligand/protein complex system were predicted by molecular docking. Besides, the ligand/protein complex system was subject to MD simulation. The analysis of molecular dynamics such as RMSD values suggested that compound/2FBW complexes were stable. MM/GBSA (Molecular mechanics generalized born surface area) dynamic binding affinity results revealed that the active residues (TYR58, HIS26, ARG43, SER39, etc.) played an essential part in the binding of the compound(s) to form a stable low-energy ligand/protein complex, while the MD trajectories demonstrated that the interactions of drugs with 2FBW affected the tertiary structure and increased the stability of protein. Besides, compound 4n also showed control efficacies (curative and protective) on Xoo in vivo, where the curative efficacy was 35.91% and the protective efficacy was 18.97%. In a word, this study showed that 1,3,4-thiadiazole sulfone derivatives containing amide moiety designed based on the structure of carboxin were promising agricultural antibacterial agents, featuring certain stability of binding affinity to proteins and carboxin.     

Temperature and Composition Dependent Optical Properties of CdSe/CdS Dot/Rod-Based Aerogel Networks

Employing nanocrystals (NCs) as building blocks of porous aerogel network structures allows the conversion of NC materials into macroscopic solid structures while conserving their unique nanoscopic properties. Understanding the interplay of the network formation and its influence on these properties like size-dependent emission is a key to apply techniques for the fabrication of novel nanocrystal aerogels. In this work, CdSe/CdS dot/rod NCs possessing two different CdSe core sizes were synthesized and converted into porous aerogel network structures. Temperature-dependent steady-state and time-resolved photoluminescence measurements were performed to expand the understanding of the optical and electronic properties of these network structures generated from these two different building blocks and correlate their optical with the structural properties. These investigations reveal the influence of network formation and aerogel production on the network-forming nanocrystals. Based on the two investigated NC building blocks and their aerogel networks, mixed network structures with various ratios of the two building blocks were produced and likewise optically characterized. Since the different building blocks show diverse optical response, this technique presents a straightforward way to color-tune the resulting networks simply by choosing the building block ratio in connection with their quantum yield.     

顺式六氢-1H-呋喃并[3,4-C]吡咯的合成

以N-（甲氧甲基）-N-（三甲基硅甲基）苄胺和马来酸二甲酯为原料通过环加成、氢化铝锂还原、T_SOH催化脱水、氢氧化钯/碳催化氢化脱苄基四步反应,设计并合成了一种含氮、氧的杂环化合物--顺式六氢-1H-呋喃并[3,4-C]吡咯,其结构经¹H NMR, ¹³ C NMR和MS（ESI）表征。      

微生物铁氧化还原作用对水中砷锑去除影响的研究进展

砷锑污染在全球领域广泛存在,与常规的铁氧化物相比,微生物铁氧化生成的含Fe(Ⅲ)矿物对水中砷/锑(As/Sb)具有更强的吸附能力,并因其高效、实用和环境友好而具有广阔的应用前景,但微生物铁还原也可能导致被吸附的As/Sb再次释放。本文综述了微生物铁氧化还原作用对As/Sb去除影响的研究进展,归纳了铁矿物“合成-溶解-转化”的微生物循环过程以及该循环伴随的水中As/Sb固定、溶解与转化机理,整合了微生物合成Fe(Ⅲ)矿物的矿物学性质、对As/Sb固定的热动力学规律和络合机制,总结了微生物合成Fe(Ⅲ)矿物对As/Sb去除的影响因素,基于该研究的现存问题展望了利用微生物铁氧化还原作用去除As/Sb的发展方向。     

Bipolar Electrode-based Electrochromic Devices for Analytical Applications – A Review

Bipolar electrode-based (BPE-based) electrochromic devices have garnered increasing attention in the past decade. These BPE-based electrochromic devices have been used for analytical health monitoring, point-of-care (POC) diagnostics, and chemical sensing. In this review, we highlight recent progress made regarding BPE-based electrochromic devices constructed for these analytical applications. Various, available electrochromic materials are summarized in the first section, after which the different device types (e. g., paper-based and self-powered) are discussed. Biological- and chemical-based analytical demonstrations of these devices are then reviewed. Finally, we conclude this review with a perspective on the future developments of BPE-based electrochromic devices in analytical applications.     

Enhanced Crystal Quality of Perovskite via Protonated Graphitic Carbon Nitride Added in Carbon-Based Perovskite Solar Cells

The quality of perovskite layers has a great impact on the performance of perovskite solar cells (PSCs). However, defects and related trap sites are generated inevitably in the solution-processed polycrystalline perovskite films. It is meaningful to reduce and passivate the defect states by incorporating additive into the perovskite layer to improve perovskite crystallization. Here an environmental friendly 2D nanomaterial protonated graphitic carbon nitride (p-g-C\begin{document}$_3$\end{document}N\begin{document}$_4$\end{document}) was successfully synthesized and doped into perovskite layer of carbon-based PSCs. The addition of p-g-C\begin{document}$_3$\end{document}N\begin{document}$_4$\end{document} into perovskite precursor solution not only adjusts nucleation and growth rate of methylammonium lead tri-iodide (MAPbI\begin{document}$_3$\end{document}) crystal for obtaining flat perovskite surface with larger grain size, but also reduces intrinsic defects of perovskite layer. It is found that the p-g-C\begin{document}$_3$\end{document}N\begin{document}$_4$\end{document} locates at the perovskite core, and the active groups -NH\begin{document}$_2$\end{document}/NH\begin{document}$_3$\end{document} and NH have a hydrogen bond strengthening, which effectively passivates electron traps and enhances the crystal quality of perovskite. As a result, a higher power conversion efficiency of 6.61% is achieved, compared with that doped with g-C\begin{document}$_3$\end{document}N\begin{document}$_4$\end{document} (5.93%) and undoped one (4.48%). This work demonstrates a simple method to modify the perovskite film by doping new modified additives and develops a low-cost preparation for carbon-based PSCs.     

Thermal characteristics of dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate in contact with nitrocellulose/nitroglycerine under continuous heat flow

Dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50) and nitrocellulose/nitroglycerine (NC/NG) possess good energy properties, which were widely used in propellants, explosives and pyrotechnics. They are easy to contact with each other during their application and storage. However, their thermal characteristics under continuous heat flow have not been reported yet. Therefore, it is of great practical significance to study the thermal properties of TKX-50/NC/NG (mixture of TKX-50 and NC/NG). In this paper, the thermal characteristics and pressure behaviors of TKX-50/NC/NG, TKX-50 and NC/NG were characterized by high pressure differential scanning calorimetry (HPDSC) and adiabatic scanning calorimetry (ASC). The results showed that TKX-50 and NC/NG can promote each other to decompose under continuous heat flow, especially the thermal decomposition which affected by gases generation and heat feedback was more violent in the confined space. The decomposition peak temperature of TKX-50/NC/NG shifted to low temperature when the heat loss was ignored and the removal of decomposition gas was suppressed. The possible decomposition mechanism of TKX-50/NC/NG was speculated. It was considered that the intermediate products of TKX-50 and NC/NG decomposition under thermal stimulation would react with each other, which promoted TKX-50/NC/NG decomposition in one step at lower temperature. Thus, TKX-50 has high reactivity and high potential risk after contact with NC/NG under continuous heat flow. TKX-50 is not suitable for application with NC/NG. This study provides a reference for the structural design of nitrogen rich explosives and further broadens the researchers’ understanding of the application of TKX-50.     

Effects of Coverage,Water, and Defects on Catechol/TiO2 Interface

Catechol adsorbed on TiO₂ is one of the simplest models to explore the relevant properties of dye-sensitized solar cells. However, the effects of water and defects on the electronic levels and the excitonic properties of the catechol/TiO₂ interface have been rarely explored. Here, we investigate four catechol/TiO₂ interfaces aiming to study the influence of coverage, water, and defects on the electronic levels and the excitonic properties of the catechol/TiO₂ interface through the first-principles many-body Green's function theory. We find that the adsorption of catechol on the rutile (110) surface increases the energies of both the TiO₂ valence band maximum and conduction band minimum by approximately 0.7 eV. The increasing coverage and the presence of water can reduce the optical absorption of charge-transfer excitons with maximum oscillator strength. Regarding the reduced hydroxylated TiO₂ substrate, the conduction band minimum decreases greatly, resulting in a sub-bandgap of 2.51 eV. The exciton distributions in the four investigated interfaces can spread across several unit cells, especially for the hydroxylated TiO₂ substrate. Although the hydroxylated TiO₂ substrate leads to a lower open-circuit voltage, it may increase the separation between photogenerated electrons and holes and may therefore be beneficial for improving the photovoltaic efficiency by controlling its concentration. Our results may provide guidance for the design of highly efficient solar cells in future.     

Comparative investigation of aerial part and root in Lamiophlomis rotata using UPLC-Q-Orbitrap-MS coupled with chemometrics

Lamiophlomis rotata (Benth.) Kudo (L. rotata) belongs to Lamiaceae family, which is an important medicinal plant endemic to Qinghai Tibet Plateau. Traditionally, the whole herb of L. rotata is used for medicine, especially for the treatment of rheumatoid arthritis (RA) in clinical practise. As a result of absolute digging, the plant has a long regeneration cycle after excavation and the damage to plateau grassland ecological environment is difficult to recover. It has been encouraged to use aerial part of the plant with the purpose of protecting environment and maintaning biological diversity. At present, researchers have compared the primary metabolites and iridoids between aerial parts and roots, but there are few reports on the chemical differences and activity comparison of secondary metabolites. In order to characterize the secondary metabolites of different parts, UPLC/Q-Orbitrap-MS was employed to collect data from the extracts of aerial parts and roots, in combination with plant metabolomics technology to screen and quantify differential metabolites. At the same time, network pharmacological analysis with rheumatoid arthritis and immunity as the key words was carried out according to the identification results to clarify the active ingredients of L. rotata in the treatment of RA, so as to speculate the pharmacological effects of aerial parts and roots based on the distribution of active components. A total of 16 potential markers were selected and identified to differentiate two parts. Among them, 8 characteristic flavonoids with similar skeletons were unique in aerial parts, while the other 8 components, including 2 iridoid glycosides and 6 phenylethanoid glycosides, were detected in both aerial parts and roots, but with differentiate contents. Among the predicted 6 active components, there were 5 flavonoids, of which 3 (namely luteolin, apigenin and 2″-acetylastragalin) were still differential metabolites and mainly distributed in the aerial parts. The results revealed that certain flavonoids as potential markers made a distinction between aerial part and root of L. rotata, and were the main active components against RA, which provided a theoretical basis for the aerial parts to replace the whole herbs, and laid a material foundation for further pharmacological research.     

Paecilomyces variotii extract increases lifespan and protects against oxidative stress in Caenorhabditis elegans through SKN-1, but not DAF-16

A natural extract from Paecilomyces variotii (P. variotii extract, PVE), an endophytic fungus, has been used widely to improve agricultural crop performance and control multiple plant pathogens. Most recent studies focused on its application as a plant growth promoter, while relatively few studies have been reported on the antioxidant potential in vivo and the underlying mechanism. The present study was designed to determine the antioxidant activities of PVE and its mechanisms using Caenorhabditis elegans. Results showed that, compared to the solvent control, PVE at 1.0, 10 and 100 ng/mL significantly extended the lifespan of C. elegans by 36.60%, 59.80% and 53.30%, respectively. PVE at 10 ng/mL consistently promoted nematodes growth, but all treatments did not influence nematode fecundity, locomotion behavior, and pharyngeal pumping. Furthermore, PVE at the three tested concentrations significantly reduced accumulation of reactive oxygen species (ROS), lipofuscin, lipid and malondialdehyde (MDA) content, meanwhile significantly promoted activities of superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST) in the nematodes. Compared with the solvent control, PVE up-regulated gene expression of skn-1, mev-1, sod-3, and daf-2, but significantly down-regulated the expression of nhr-49 and daf-16. Further evidence revealed that PVE at the three concentrations significantly promoted nuclear localization of SKN-1, but not affected that of DAF-16, indicating the complex roles of DAF-16 and SKN-1 in stress resistance and longevity regulation. Overall, our results demonstrated that SKN-1 played a critical role in increasing lifespan of C. elegans and protecting the nematodes from oxidative stress, independent of DAF-16.