Controlled synthesis of Mn_(x)Cd_(1-x)S for enhanced visible-light driven photocatalytic hydrogen evolution

Ternary sulfide solid solutions have garnered great attention in photocatalytic water splitting due to their tunable electronic property,low cost,and sufficient light-absorption performance.Herein,a series of Mn_(x)Cd_(1-x)S samples with different Mn/Cd molar ratios were synthesized by solvothermal method and used for photocatalytic hydrogen production under visible light.The Mn_(0.2)Cd_(0.8)S and Mn_(0.4)Cd_(0.6)S are demonstrated to be the solid so-lutions,while Mn_(0.6)Cd_(0.4)S and Mn_(0.8)Cd_(0.2)S consist of Mn_(x)Cd_(1-x)S solid solution and MnS.In addition,the Mn_(0.4)Cd_(0.6)S exhibits the highest photocatalytic performance with the H_(2) production rate of 185.95μmol·h^(-1),which is 4.7 times higher than that of CdS.Without cocatalyst,the quantum efficiency of Mn_(0.4)Cd_(0.6)S reaches 2.04%at 400 nm.In addition,the Mn_(0.4)Cd_(0.6)S solid solution also shows high stability during the photocatalytic H_(2) production reaction.The effect of Mn/Cd molar ratio on the microstructure,band gap structure,and photo-catalytic hydrogen production performance of Mn_(x)Cd_(1-x)S was revealed systematically.The excellent photo-catalytic H_(2) production performance of Mn_(0.4)Cd_(0.6)S solid solution is mainly due to its enhanced reducing potential and high charge separation efficiency.

Stereodivergently asymmetric synthesis of chiral phosphorus compounds by synergistic combination of ion-pair catalyst and base

Stereodivergently constructing the designed products having adjacent multi-stereocenters via a given reaction,with excellent control of both absolute and relative configurations,presents one of the substantial hurdles in asymmetric catalysis.Herein,we report a precisely stereodivergent asymmetric protocol by synergistic combination of phosphonium-involved ion-pair catalysis and base for accessing to chiral phosphorus compounds bearing two adjacent chiral centers particularly containing an acidic protonated enantioenriched carbon atom,having broad functional group compatibility in both dynamic and thermodynamic processes under mild reaction conditions.Two keys for the success in constructing these stereoisomers with high levels of regio-,diastereo-,and enantioselectivities were contained:firstly,the precise stereo-control in providing dynamic products was enabled by bifunctional phosphonium salt catalyst with semi-enclosed cavity;secondly,the readily stereospecific transformation of adducts from dynamic to thermodynamic version was initiated by achiral base.All four stereoisomers could be readily accessed even in gram-scale in high yields with maintaining excellent stereoselectivities,illustrating the potential of this synergistic catalytic methodology in organic synthesis.Moreover,mechanistic studies including density functional theory(DFT)calculations and control experiments provide insights into the mechanism.

肝脏叉头状转录因子O3高表达对小鼠糖代谢的影响及机制研究

目的探讨叉头状转录因子O3(FOXO3)在小鼠肝脏糖代谢中的作用。方法将雄性肝脏激活蛋白(LAP)启动子控制下且表达四环素调节的反式激活因子(tTA)的转基因小鼠(LAP-tTA小鼠)与雌性荧光素酶-tet操作元件(tetO)7-FOXO3的组成型活性等位基因小鼠[(tetO)7.FOXO3CA小鼠]杂交,获得FOXO3CAhep小鼠(tTA+/FOXO3CA+,肝脏FOXO3条件性高表达,7只)。以tTA-和(或)FOXO3CA-小鼠作为对照组(9只)。通过IVIS活体成像、实时荧光定量聚合酶链反应(RT-qPCR)、Western blotting以及免疫组化检测各组小鼠肝脏FOXO3表达情况,RT-qPCR检测相关糖异生基因[葡萄糖6-磷酸酶(G6pc)、磷酸烯醇丙酮酸羧化激酶(Pepck)、丙酮酸脱氢酶激酶4(Pdk4)]的mRNA水平。监测小鼠血糖、血清胰岛素,并进行葡萄糖耐量实验以及胰岛素耐量实验。利用免疫组织化学染色评估胰腺胰岛增生、胰岛素以及胰高血糖素表达。组间比较采用t检验。结果IVIS活体成像、RT-qPCR、Western blotting以及免疫组化证实FOXO3CAhep小鼠肝脏FOXO3高表达,且主要表达于肝细胞核内,FOXO3高表达导致肝细胞体积明显小于对照组肝细胞。与对照组相比,7周龄FOXO3CAhep小鼠的空腹血糖水平显著升高[分别为(165.7±24.1)和(87.4±12.1)mg/dl,P<0.001],糖异生基因G6pc、Pepck、Pdk4的mRNA水平显著增加(均P<0.001)。与对照组相比,9周龄FOXO3CAhep小鼠空腹血糖下降[分别为(55.6±6.1)和(82.8±17.2)mg/dl,P=0.001],胰岛素水平显著升高[分别为(10.01±1.56)和(1.50±0.82)ng/ml,P<0.001]。免疫组织化学染色结果提示,FOXO3CAhep小鼠较对照组胰岛细胞显著增生,胰岛细胞呈现胰岛素强阳性,胰岛素耐量实验提示存在胰岛素抵抗。结论FOXO3持续高表达可促进肝脏糖异生相关基因的上调、血糖紊乱和胰岛素水平升高、胰岛增生及胰岛素抵抗。

Microstructure and mechanical properties of A356 alloy with yttrium addition processed by hot extrusion

The effects of the rare earth element yttrium(Y) and hot extrusion on the microstructure and mechanical properties of A356 alloy were investigated by mechanical properties testing and microstructure observation. The results indicate that the addition of Y improves the microstructure of the as-cast alloy. The distribution of primary α-Al is uniform and orderly. The long needle-like eutectic Si phases and β-Fe phases turn to strips and short rods. When the content of Y increases to 0.2 wt%, the mean diameter of aAl(40.3 μm) and the aspect ratio of the eutectic Si phase(2.3) reach the minimum values, which are68.9% and 86.1% lower, respectively, than that of the alloy without Y addition. Under extrusion stress, the shape of the eutectic Si phase is changed from long rod-like to near grain-like after solution treatment.The size of the eutectic Si phase is significantly reduced. The needle-like β-Fe phases are squeezed and broken. The mechanical properties of the as-extruded alloy are significantly improved compared to the as-cast alloy. When the rare earth content is 0.2 wt%, the ultimate tensile strength, hardness and elongation of the alloy reach the maximum values, which are 328.2 MPa, 110.4 HV and 21.3%, respectively, and increase by 42.01%, 37.71% and 481.91%, respectively, in comparison to the as-cast alloy without Y addition.

TwoMADS-boxgenes regulate vascularcambium activity and secondary growth by modulating auxin homeostasis in Populus

In trees,stem secondary growth depends on vascular cambium proliferation activity and subsequent cell differentiation,in which an auxin concentration gradient across the cambium area plays a crucial role in regulating the process.However,the underlying molecular mechanismfor the establishment of auxin concentration is not fully understood.In this study,we identified two function-unknown MADS-box genes,VCM1 and VCM2,which are expressed specifically in the vascular cambium and modulate the subcellular homeostasis of auxin.Simultaneous knockdown of both VCM1 and VCM2 enhanced vascular cambium proliferation activity and subsequent xylem differentiation.Overexpression of VCM1 suppressed vascular cambium activity and wood formation by regulating PIN5 expression,which tuned the soluble auxin concentration in the vascular cambium area.This study reveals the role of VCM1 and VCM2 in regulating the proliferation activity of the vascular cambium and secondary growth by modulating the subcellular auxin homeostasis in Populus.

多光子显微技术在乳腺癌预后预测的应用

乳腺癌是全世界最广泛的女性癌症类型,同样也是女性癌症死亡的主要原因。2020年乳腺癌发病数已经超过肺癌,成为了全球第一大癌。多光子显微技术(MPM)是基于激光与生物组织相互作用发生的多光子激发荧光和谐波等非线性光学效应的一种先进医学成像技术。多光子显微技术不但在成像分辨率上具有与组织病理学分辨率相当的优势,而且具有无标记、免切片、光学层析成像、反映细胞的功能代谢信息、三维靶向消融能力、较低的光漂白与光损伤、高成像对比度等优势。因此,多光子显微技术在医学病理诊断,特别是肿瘤病理诊断临床转化的基础研究和应用研究领域一直受到广泛的关注。本文详细阐述了多光子显微技术在乳腺肿瘤微环境预后预测研究中的应用进展,并展望了其未来发展前景。