Exploration of Ligand-Centered Hydride Transfer in La/Y-Catalyzed Deoxygenative Reduction of Tertiary Amides with Pinacolborane.

A number of rare-earth metals and actinides have proven to be active in a wide variety of atom-efficient transformations. As compared to the related organometallic catalysts, the detailed mechanisms for the rare-earth metal-catalyzed reactions remain largely unexplored. Herein, the detailed catalyst activation process and reaction mechanisms of deoxygenative reduction of amides with pinacolborane (HBpin) catalyzed by Y[N(TMS)2]3 and La[N(TMS)2]3 complexes as well as a La4(O)acac10 cluster are investigated by density functional theory calculations. The M(III)-hemiaminal complex is disclosed to be the active catalyst for both the complexes and the cluster. During catalyst activation for both the Y and La complexes, the H-B bond polarity results in the formation of a transient M(III)-hydride intermediate, which is converted into an on-cycle M(III)-hemiaminal complex via facile migratory insertion. However, this kind of La(III)-hydride species cannot be formed for the La cluster. Starting from the M(III)-hemiaminal complex, the reaction proceeds via the ligand-centered hydride transfer mechanism that involves B-O bond formation, hydride transfer to B, C-O cleavage within the hemiaminal borane, hydride transfer to C, and σ-bond metathesis. The additional HBpin molecule is vital for the first hydride transfer that leads to the formation of [H2Bpin]- species. Our calculations reveal several important cooperative effects of the HBpin component during the hydride transfer processes. The improved mechanistic insights will be helpful for further development of selective C═O reduction.

The Classification, Molecular Structure and Biological Biosynthesis of Flavonoids, and Their Roles in Biotic and Abiotic Stresses.

With the climate constantly changing, plants suffer more frequently from various abiotic and biotic stresses. However, they have evolved biosynthetic machinery to survive in stressful environmental conditions. Flavonoids are involved in a variety of biological activities in plants, which can protect plants from different biotic (plant-parasitic nematodes, fungi and bacteria) and abiotic stresses (salt stress, drought stress, UV, higher and lower temperatures). Flavonoids contain several subgroups, including anthocyanidins, flavonols, flavones, flavanols, flavanones, chalcones, dihydrochalcones and dihydroflavonols, which are widely distributed in various plants. As the pathway of flavonoid biosynthesis has been well studied, many researchers have applied transgenic technologies in order to explore the molecular mechanism of genes associated with flavonoid biosynthesis; as such, many transgenic plants have shown a higher stress tolerance through the regulation of flavonoid content. In the present review, the classification, molecular structure and biological biosynthesis of flavonoids were summarized, and the roles of flavonoids under various forms of biotic and abiotic stress in plants were also included. In addition, the effect of applying genes associated with flavonoid biosynthesis on the enhancement of plant tolerance under various biotic and abiotic stresses was also discussed.

Genome-wide identification and characterization of PdbHLH transcription factors related to anthocyanin biosynthesis in colored-leaf poplar (Populus deltoids).

Basic helix-loop-helix (bHLH) proteins are transcription factors (TFs) that have been shown to regulate anthocyanin biosynthesis in many plant species. However, the bHLH gene family in Populus deltoids has not yet been reported. In this study, 185 PdbHLH genes were identified in the Populus deltoids genome and were classified into 15 groups based on their sequence similarity and phylogenetic relationships. Analysis of the gene structure, chromosome location and conserved motif of the PdbHLH genes were performed by bioinformatic methods. Gene duplication analyses revealed that 114 PdbHLH were expanded and retained after WGD/segmental and proximal duplication. Investigation of cis-regulatory elements of PdbHLH genes indicated that many PdbHLH genes are involved in the regulation of anthocyanin biosynthesis. The expression patterns of PdbHLHs were obtained from previous data in two colored-leaf poplar (QHP and JHP) and green leaf poplar (L2025). Further analysis revealed that 12 candidate genes, including 3 genes (PdbHLH57, PdbHLH143, and PdbHLH173) from the subgroup III(f) and 9 gene from other groups, were positively associated with anthocyanin biosynthesis. In addition, 4 genes (PdbHLH4, PdbHLH1, PdbHLH18, and PdbHLH164) may be involved in negatively regulating the anthocyanin biosynthesis. These results provide a basis for the functional characterization of bHLH genes and investigations on the molecular mechanisms of anthocyanin biosynthesis in colored-leaf poplar.

Recent research on immunotherapy for anti-N-methyl-D-aspartate receptor encephalitis. / 抗N-甲基-D-å¤©å†¬æ°¨é ¸å—ä½“è„‘ç‚Žå ç–«æ²»ç–—çš„ç ”ç©¶è¿›å±•.

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a central nervous system disease characterized by neurological and psychiatric symptoms. Immunotherapy is the basic treatment for this disease, including first- and second-line therapies for the acute stage and the long-course therapy for the chronic stage. Anti-NMDAR encephalitis often has a good prognosis, but some patients may still have neurological dysfunction due to poor response to current immunotherapy. In addition, the adverse reactions and economic burden of drugs are practical problems in clinical practice. To solve the above problems, continuous improvements have been made in immunotherapy regimens in terms of dose, route of administration, and course of treatment, and some new immunotherapy drugs have emerged. This article reviews the recent research on immunotherapy for anti-NMDAR encephalitis.

Spin Fluctuations in Quantized Transport of Magnetic Topological Insulators.

In magnetic topological insulators, quantized electronic transport is intertwined with spontaneous magnetic ordering, as magnetization controls band gaps, hence band topology, through the exchange interaction. We show that considering the exchange gaps at the mean-field level is inadequate to predict phase transitions between electronic states of distinct topology. Thermal spin fluctuations disturbing the magnetization can act as frozen disorders that strongly scatter electrons, reducing the onset temperature of quantized transport appreciably even in the absence of structural impurities. This effect, which has hitherto been overlooked, provides an alternative explanation of recent experiments on magnetic topological insulators.

Robust Cr(VI) reduction over hydroxyl modified UiO-66 photocatalyst constructed from mixed ligands: Performances and mechanism insight with or without tartaric acid.

Hydroxyl modified UiO-66 ((OH)2-UiO-66-X%, X represents the mass content ratio of introduced 2,5-dihydroxyterephthalic acid) was prepared via a solvothermal reaction between zirconium tetrachloride, benzene-1,4-dicarboxylic acid (H2BDC), as well as 2,5-dihydroxyterephthalic acid (H2BDC-(OH)2). It was found that hydroxyl groups can act as the intramolecular hole scavenger to boost the photo-induced charge carrier separation to enhance Cr(VI) reduction. The photocatalytic Cr(VI) reduction activities of (OH)2-UiO-66-X% were investigated upon the irradiation of low-power ultraviolet LED light. The findings demonstrated that (OH)2-UiO-66-20% with good cyclicity and stability exhibited superior photocatalytic performances to both UiO-66 and (OH)2-UiO-66. The introduction of hydroxyl groups can also extend the light absorption region to longer wavelength in visible range, which provides possibility for displaying photocatalytic activities under sunlight. The effect of small molecule organic acid (SOAs), pH value, and co-existing inorganic ions on photocatalytic performances of (OH)2-UiO-66-20% were investigated. Tartaric acid (TA) as typical SOAs was introduced to the reaction system to further boost the photocatalytic Cr(VI) reduction via acting as hole scavenger, constructing charge-transfer-complex for quick electron transportation, and producing COO·- radicals. This work opened a new opportunity for modified MOFs for boosted elimination activities for environmental pollutants.

HSP90 regulates osteosarcoma cell apoptosis by targeting the p53/TCF-1-mediated transcriptional network.

Osteosarcoma (OS) is the most common bone tumor that occurs predominantly in children and teenagers. Although many genes, such as p53 and Rb1, have been shown to be mutated, deregulation of the canonical Wnt/ß-catenin signaling pathway is frequently observed in OS. We recently demonstrated that heat shock protein 90 (HSP90) is involved in the regulation of runt-related transcription factor 2 via the AKT/GSK-3ß/ß-catenin signaling pathway in OS. However, the precise role of T cell factors/lymphoid enhancer-binding factor (TCFs/LEF) family members, which are the major binding complex of ß-catenin, in OS is poorly understood. In the present study, we first demonstrated that TCF-1 is overexpressed in OS compared with other bone tumors. Knockdown of TCF-1 significantly induced cell cycle arrest, severe DNA damage, and subsequent caspase-3-dependent apoptosis. Interestingly, coexpression of HSP90 and TCF-1 was observed in OS, and mechanistically, we demonstrated that TCF-1 expression is regulated by HSP90 either through a ß-catenin-dependent mechanism or a direct degradation of the proteasome. We also found that overexpression of TCF-1 partially abolishes the apoptosis induced by HSP90 inhibition. Furthermore, we provided evidence that p53, but not miR-34a, plays a crucial role in the HSP90-regulated TCF-1 expression and subsequent apoptosis. Given the diverse combination regimens of HSP90 inhibition with some other treatments, we propose that the p53 status and the expression level of TCF-1 should be taken into consideration to enhance the therapeutic efficacy of HSP90 inhibition.

Elevated expression of ICAM-1 in synovium is associated with early inflammatory response for cartilage degeneration in type 2 diabetes mellitus.

Type 2 diabetes mellitus (T2DM) is increasingly being recognized as an independent risk factor for the onset and progression of osteoarthritis (OA). Extensive studies have focused on the contribution of obesity (excessive mechanical stress), comorbidity frequently found in T2DM, to cartilage destruction during OA development. However, a little is known about how diabetes-related inflammation may affect the local cartilage in a diabetic objective. In the present study, we were able to establish a T2DM rat model using a combination of a low dose of streptozotocin with high-fat and high-sugar diet. Although the cartilage integrity was comparable between the control and T2DM groups, the expression of matrix metalloproteinases-13 (MMP-13) was significantly upregulated in T2DM, indicating the initiation of an early cascade of cartilage degeneration. In parallel, an obvious alteration of subchondral bone remodeling (inhibition of bone formation) was observed, as evidenced by the reduction of osterix-expressing positive cells. Moreover, we demonstrated that the expression of intercellular adhesion molecule-1 (ICAM-1) in the serum and synovium of T2DM rats was elevated, accompanied by an increase of synovitis score. We also noticed that the number of F4/80-positive macrophage cells was significantly increased in the T2DM group. Mechanistically, the expression of ICAM-1 in fibroblast-like synoviocytes can be triggered by glucose and interleukin-1ß, which are the two important factors within the joint of T2DM. Given that MMP-13 expression was significantly upregulated in the T2DM cartilage, and that ICAM-1-mediated filtration of macrophage was associated with synovitis, we propose that ICAM-1 is essential for triggering a vicious cycle of inflammation within the joint, which together subsequently drivers the cartilage degradation.

Sharp-Tipped Zinc Nanowires as an Efficient Electrocatalyst for Carbon Dioxide Reduction.

Electrochemical carbon dioxide reduction is a key reaction for carbon dioxide conversion to valuable fuels and chemicals. Due to the intrinsic stability of the carbon dioxide molecule, a catalyst is required to minimize the energy input and improve the reaction rates. Although the developed catalysts still suffer from low catalytic activity, selectivity, and stability, these could be enhanced by the involvement of sharp tip structure. Here, we report a nanowire-like zinc electrocatalyst with sharp tips for carbon dioxide reduction. The catalyst achieves a geometry current density of -40 mA cm-2 at a potential of -0.95 V versus reversible hydrogen electrode over 35 hours with a stable carbon monoxide Faradaic efficiency of 98±2 %. The carbon monoxide partial current density surpasses by 60 % of that of the best reported zinc catalyst.

The BET Bromodomain Inhibitor JQ1 Suppresses Chondrosarcoma Cell Growth via Regulation of YAP/p21/c-Myc Signaling.

Chondrosarcoma, the second-most frequent primary bone malignancy, is generally more resistant to conventional chemotherapy and radiotherapy. Therefore, the development of an effective adjuvant therapy is necessary. Recently, targeting the epigenetic regulator such as bromodomain and extraterminal domain (BET) proteins has achieved great success. For instance, the bromodomain inhibitor JQ1 has been shown to inhibit the growth of several cancer cells both in vitro and in vivo. Herein, we demonstrated that JQ1 significantly inhibited chondrosarcoma cell growth and colony formation. JQ1 also induced marked G1-phase cell cycle arrest coincided with the up-regulation of p21WAF1/CIP1 , p27Kip1 , and Cyclin D1 expression, and the down-regulation of Cyclin E2 expression. Moreover, JQ1 induced the premature senescence of SW 1353 cells, and that prolong treatment of JQ1 caused cell apoptosis. Mechanistically, the JQ1-induced cell growth inhibition was correlated with the suppression of c-Myc and Bcl-xL, which are the prime genes for cell cycle control and anti-apoptosis. Furthermore, we demonstrated that p21 negatively regulated the expression of c-Myc and Bcl-xL upon JQ1 treatment, and that the growth inhibition of SW 1353 and Hs 819.T cells and induction of p21 were predominantly regulated by the LATS1/YAP signaling but not through a p53-dependent manner. In conclusion, we disclosed a novel mechanism that JQ1 inhibits cell proliferation, induces cell senescence and apoptosis of chondrosarcoma cells through the regulation of the YAP/p21/c-Myc/Bcl-xL signaling axis. J. Cell. Biochem. 118: 2182-2192, 2017. © 2017 Wiley Periodicals, Inc.

Metallic Ni3 P/Ni Co-Catalyst To Enhance Photocatalytic Hydrogen Evolution.

Metallic Ni3 P/Ni can be used as a co-catalyst to replace noble metal Pt for efficient photocatalytic hydrogen evolution, due to its excellent trapping-electron ability. The applications of metallic Ni3 P/Ni co-catalyst on CdS, Zn0.5 Cd0.5 S, TiO2 (Degussa P25) and g-C3 N4 are further confirmed, indicating its versatile applicability nature like Pt.

Black Tungsten Nitride as a Metallic Photocatalyst for Overall Water Splitting Operable at up to 765†nm.

Semiconductor photocatalysts are hardly employed for overall water splitting beyond 700 nm, which is due to both thermodynamic aspects and activation barriers. Metallic materials as photocatalysts are known to overcome this limitation through interband transitions for creating electron-hole pairs; however, the application of metallic photocatalysts for overall water splitting has never been fulfilled. Black tungsten nitride is now employed as a metallic photocatalyst for overall water splitting at wavelengths of up to 765 nm. Experimental and theoretical results together confirm that metallic properties play a substantial role in exhibiting photocatalytic activity under red-light irradiation for tungsten nitride. This work represents the first red-light responsive photocatalyst for overall water splitting, and may open a promising venue in searching of metallic materials as efficient photocatalysts for solar energy utilization.

Orange Zinc Germanate with Metallic Ge-Ge Bonds as a Chromophore-Like Center for Visible-Light-Driven Water Splitting.

The efficiency of solar-energy-conversion devices depends on the absorption region and intensity of the photon collectors. Organic chromophores, which have been widely stabilized on inorganic semiconductors for light trapping, are limited by the interface between the chromophore and semiconductor. Herein we report a novel orange zinc germanate (Zn-Ge-O) with a chromophore-like structure, by which the absorption region can be dramatically expanded. Structural characterizations and theoretical calculations together reveal that the origin of visible-light response can be attributed to the unusual metallic Ge-Ge bonds which act in a similar way to organic chromophores. Benefiting from the enhanced light harvest, the orange Zn-Ge-O demonstrates superior capacity for solar-driven hydrogen production.

Cluster size effects of platinum oxide as active sites in hydrogen evolution reactions.

The successful design of photocatalytic hydrogen generation from water relies on a thorough understanding of the role of cocatalyst. The photoreactivity was studied as a function of the cluster size of the oxidized platinum cocatalyst. The maximum turnover frequency is found on the smallest-sized cocatalyst. This effect can be attributed to the size-dependent proton adsorption.

Stable isolated metal atoms as active sites for photocatalytic hydrogen evolution.

The process of using solar energy to split water to produce hydrogen assisted by an inorganic semiconductor is crucial for solving our energy crisis and environmental problems in the future. However, most semiconductor photocatalysts would not exhibit excellent photocatalytic activity without loading suitable co-catalysts. Generally, the noble metals have been widely applied as co-catalysts, but always agglomerate during the loading process or photocatalytic reaction. Therefore, the utilization efficiency of the noble co-catalysts is still very low on a per metal atom basis if no obvious size effect exists, because heterogeneous catalytic reactions occur on the surface active atoms. Here, for the first time, we have synthesized isolated metal atoms (Pt, Pd, Rh, or Ru) stably by anchoring on TiO2 , a model photocatalystic system, by a facile one-step method. The isolated metal atom based photocatalysts show excellent stability for H2 evolution and can lead to a 6-13-fold increase in photocatalytic activity over the metal clusters loaded on TiO2 by the traditional method. Furthermore, the configurations of isolated atoms as well as the originality of their unusual stability were analyzed by a collaborative work from both experiments and theoretical calculations.

High spin axion insulator.

Axion insulators possess a quantized axion field θ = π protected by combined lattice and time-reversal symmetry, holding great potential for device applications in layertronics and quantum computing. Here, we propose a high-spin axion insulator (HSAI) defined in large spin-s representation, which maintains the same inherent symmetry but possesses a notable axion field θ = (s + 1/2)2π. Such distinct axion field is confirmed independently by the direct calculation of the axion term using hybrid Wannier functions, layer-resolved Chern numbers, as well as the topological magneto-electric effect. We show that the guaranteed gapless quasi-particle excitation is absent at the boundary of the HSAI despite its integer surface Chern number, hinting an unusual quantum anomaly violating the conventional bulk-boundary correspondence. Furthermore, we ascertain that the axion field θ can be precisely tuned through an external magnetic field, enabling the manipulation of bonded transport properties. The HSAI proposed here can be experimentally verified in ultra-cold atoms by the quantized non-reciprocal conductance or topological magnetoelectric response. Our work enriches the understanding of axion insulators in condensed matter physics, paving the way for future device applications.

Two new diatom species of the genus Gomphonemopsis (Bacillariophyceae) from the coast of China and two new combinations for the genus.

Two new diatom species belonging to the genus Gomphonemopsis are described, Gomphonemopsisnanasp. nov. and Gomphonemopsisgaoisp. nov. These two species were compared in detail with congeners. Gomphonemopsisnana is distinguished by its high stria density and small size. This species was found so far to be epiphytic only on the eelgrass collected from Qingdao Bay (Yellow Sea). Gomphonemopsisgaoi is characterized by its isopolar valves, simple proximal raphe endings and acutely rounded apices. This taxon was separated from the exoskeleton of marine copepods sampled from the Futian Mangrove Nature Reserve (South China Sea). In addition, two new combinations, Gomphonemopsisoahuensis (Hustedt) Lang Li, Yuhang Li & Changping Chen, comb. nov. and Gomphonemopsisplatypus (Østrup) Lang Li, Yuhang Li & Junxiang Lai, comb. nov. are proposed. This study increases the records and knowledge of Gomphonemopsis along the coast of China.

Recent research progress on tumour-specific responsive hydrogels.

Most existing hydrogels, even recently developed injectable hydrogels that undergo a reversible sol-gel phase transition in response to external stimuli, are designed to gel immediately before or after implantation/injection to prevent the free diffusion of materials and drugs; however, the property of immediate gelation leads to a very weak tumour-targeting ability, limiting their application in anticancer therapy. Therefore, the development of tumour-specific responsive hydrogels for anticancer therapy is imperative because tumour-specific responses improve their tumour-targeting efficacy, increase therapeutic effects, and decrease toxicity and side effects. In this review, we introduce the following three types of tumour-responsive hydrogels: (1) hydrogels that gel specifically at the tumour site; (2) hydrogels that decompose specifically at the tumour site; and (3) hydrogels that react specifically with tumours. For each type, their compositions, the mechanisms of tumour-specific responsiveness and their applications in anticancer treatment are comprehensively discussed.

Strategy to Efficient Photodynamic Therapy for Antibacterium: Donor-Acceptor Structure in Hydrogen-Bonded Organic Framework.

While the construction of a donor-acceptor (D-A) structure has gained great attention across various scientific disciplines, such structures are seldomly reported within the field of hydrogen-bonded organic frameworks (HOFs). Herein, a D-A based HOF is synthesized, where the adjacent D-A pairs are connected by hydrogen bonds instead of the conventionally employed covalent bonds. This structural feature imparts material with a reduced energy gap between excited state and triplet state, thereby facilitating the intersystem crossing (ISC) and boosting the generation rate of single oxygen (quantum yield = 0.98). Consequently, the resulting material shows high performance for antimicrobial photodynamic therapy (PDT). The impact of D-A moiety is evident when comparing this finding to a parallel study conducted on an isoreticular HOF without a D-A structure. The study presented here provides in-depth insights into the photophysical properties of D-A pair in a hydrogen-bonded network, opening a new avenue to the design of innovative materials for efficient PDT.

Ultrafast removal of organics via peroxymonosulfate activation over Co2P/TD hollow spheres derived from ZIF-67.

Co2P/tetrasodium diphosphate (TD) derived from ZIF-67/sodium phytate was newly developed and synthesized, and exhibited excellent degradation ability toward various refractory organics via peroxymonosulfate activation. A corresponding reaction mechanism was proposed. In addition, a continuous-flow operation of phenol degradation was realized.