Benzyl alcohol oxidation and hydrogen generation over MoS2/ZnIn2S4 composite photocatalyst

Research on Chemical Intermediates - Owing to the simultaneous utilization of photogenerated electrons and holes, coupling light-driven hydrogen (H2) evolution reaction (HER) and biomass-derived...     

alb聚铝离子稳定性的温度效应及硫酸盐沉淀形态

alb聚铝离子;稳定性;温度效应;硫酸盐沉淀;al-ferron络合比色法     

木糖-软模板水热法制备硼掺杂分级多孔炭球及其电化学性能

以D-木糖为炭源,月桂酸钠为模板剂,硼酸为掺杂剂,通过水热炭化方法制得硼掺杂分级多孔炭球（BPC_S）。通过扫描电子显微镜（SEM）、透射电子显微镜（TEM）、N₂吸附-脱附测试、X射线光电子能谱（XPS）、顺磁共振波谱（EPR）、傅里叶红外光谱（FT-IR）、拉曼光谱（Raman）、X射线粉末衍射（XRD）、热重（TG）分析对样品进行表征。结果表明：月桂酸钠作为介孔造孔剂的同时,通过与D-木糖间的氢键作用使有机-有机自组装过程自发进行并形成窄尺寸分布（2~5 μm）规整炭球;硼酸在水热中催化炭源脱水降解,并以BC₃、BCO₂和BC₂O的形式掺杂在炭球上,掺硼后炭球与水表面接触角降低,润湿性提高。经CO₂活化、月桂酸钠高温分解以及胶质炭球的堆积分别产生微孔（0.5~1.2 nm）、介孔（3.14~35.00 nm）和大孔（60~146 nm）并形成分级结构。当硼酸加入量为0.927 5 g时多孔炭球（BPC_S-1）的电化学性能最佳,在6 mol·L^-1 KOH三电极体系中电流密度为0.5 A·g^-1时,比电容达287.12 F·g^-1;两电极体系中电流密度为0.5 A·g^-1时比电容达151.34 F·g^-1,能量密度达5.3 Wh·kg^-1;电流密度为5 A·g^-1时进行1 000次充放电循环,电容保持率仍达96.43%。     

双温度氩-氮等离子体热力学和输运性质计算

获得覆盖较宽温度和压力范围内的等离子体热力学和输运性质是开展等离子体传热和流动过程数值模拟的必要条件.本文通过联立Saha方程、道尔顿分压定律以及电荷准中性条件求解等离子体组分;采用理想气体动力学理论计算等离子体热力学性质;基于Chapman-Enskog方法求解等离子体输运性质.利用上述方法计算了压力为0.1, 1.0和10.0 atm (1 atm=101325 Pa),电子温度在300—30000 K范围内,非局域热力学平衡(电子温度不等于重粒子温度)条件下氩-氮等离子体的热力学和输运性质.结果表明压力和非平衡度会影响等离子体中各化学反应过程,从而对氩-氮等离子体的热力学及输运性质有较大的影响.在局域热力学平衡条件下,计算获得的氩-氮等离子体输运性质和文献报道的数据符合良好.     

Effective suppression of beta oscillation in Parkinsonian state via a noisy direct delayed feedback control scheme

This work explores the function of the noisy direct delayed feedback(NDDF)control strategy in suppressing the pathological oscillations in the basal ganglia(BG)with Parkinson’s disease(PD).Deep brain stimulation(DBS)alleviates the PD state fantastically.However,due to its unclear mechanism and open-loop characteristic,it is challenging to further improve its effects with lower energy expenditure.The noise stimulus performs competitively in alleviating the PD state theoretically,but it cannot adapt to the neural condition timely and automatically due to its open-loop control scheme.The direct delayed feedback(DDF)control strategy is able to disturb excessive synchronous effectively.Therefore,the NDDF control strategy is proposed and researched based on a BG computational model,which can reflect the intrinsic properties of the BG neurons and their connections with thalamic neurons.Simulation results show that the NDDF control strategy with optimal parameters is effective in removing the pathological beta oscillations.By comparison,we find the NDDF control strategy performs more excellent than DDF in alleviating PD state.Additionally,we define the multiple-NDDF control strategy and find that the multiple-NDDF with appropriate parameters performs better than NDDF.The obtained results contribute to the cure for PD symptoms by optimizing the noise-induced improvement of the BG dysfunction.     

Air-Stable Hexagonal Bipyramidal Dysprosium(III) Single-Ion Magnets with Nearly Perfect D6h Local Symmetry

Eight-coordinated Dy^III centres with D_6h symmetry are expected to act as high-performance single-molecule magnets (SMMs) due to the simultaneous fulfilment of magnetic axiality and a high coordination number (a requisite for air stability). But the experimental realization is challenging due to the requirement of six coordinating atoms in the equatorial plane of the hexagonal bipyramid; this is usually too crowded for the central Dy^III ion. Here a hexaaza macrocyclic Schiff base ligand and finetuned axial alkoxide/phenol-type ligands are used to show that a family of hexagonal bipyramidal Dy^III complexes can be isolated. Among them, three complexes possess nearly perfect D_6h local symmetry. The highest effective magnetic reversal barrier is found at 1338(3) K and an open hysteresis temperature of 6 K at the field sweeping rate of 1.2 mT s⁻¹; this represents a new record for D_6h SMMs.     

飞秒激光加工蓝宝石超衍射纳米结构

蓝宝石具有超强硬度及耐腐蚀、耐高温、在紫外-红外波段具有良好的透光性等优点,在军工业以及医疗器械方面具有广泛的应用前景.然而这些优点又对蓝宝石的机械加工或化学腐蚀加工带来困难.飞秒激光脉冲具有热损伤小、加工分辨率高、材料选择广等特点,被广泛应用于固体材料改性和高精度三维微纳器件加工.本文提出了利用飞秒激光多光子吸收特性在蓝宝石表面实现超越光学衍射极限的精细加工.利用聚焦后的波长为343 nm的飞秒激光,配合高精密三维压电位移台,实现激光焦点和蓝宝石晶体的相对三维移动,在蓝宝石晶体衬底上进行精确扫描,得到了线宽约61 nm的纳米线,纳米线间的最小间距达到142 nm左右.利用等离子体模型解释了加工得到的纳米条纹的产生原因,研究了激光功率、扫描速度对加工分辨率的影响.最终本工作实现了超越光学衍射极限的加工精度,为实现利用飞秒激光对高硬度材料的微纳结构制备提供了参考.     

B元素添加对Co-Zr-Mo合金薄带的磁性能及结构的影响

利用X射线和磁性测量研究了Co_77Zr（18-x）Mo₅B_x合金薄带的结构和磁性.实验发现,在Co-Zr-Mo合金中添加适当含量的B,可以使其矫顽力显著提高,当x=2.0时,制备出具有迄今为止Co-Zr基永磁合金最大矫顽力H_c=7.0 kOe（1 Oe=79.5775 A/m）的快淬薄带.随着B元素添加,Co₇₇Zr_18-xMo₅B_x合金薄带的晶粒逐渐细化,并根据Henkel plot模型计算得出软磁相fcc-Co与硬磁相Co₅Zr相之间的交换耦合作用逐渐增强.合金薄带的矫顽力主要受硬磁相Co₅Zr相的晶粒尺寸控制,并随着晶粒尺寸的减小先升高后降低.另一方面,Co₇₇Zr₁₈Mo₅合金薄带的矫顽力机理为反磁化核形核模型,添加B元素之后矫顽力机理变为畴壁钉扎模型.通过X射线衍射和热磁分析发现,B元素并没有进入到Co₅Zr相的晶格中,而是存在于非晶相中.     

In Situ Visual Distribution of Gelsemine,Koumine, and Gelsenicine by MSI in Gelsemium elegans at Different Growth Stages

The distribution of pharmatically important alkaloids gelsemine, koumine, and gelsenicine in Gelsemium elegans tissues is a hot topic attracting research attention. Regretfully, the in planta visual distribution details of these alkaloids are far from clear although several researches reported the alkaloid quantification in G. elegans by LC-MS/MS. In this study, mass imaging spectrometry (MSI) was employed to visualize the in situ visualization of gelsemine, koumine, and gelsenicine in different organs and tissues of G. elegans at different growth stages, and the relative quantification of three alkaloids were performed according to the image brightness intensities captured by the desorption electrospray ionization MSI (DESI-MSI). The results indicated that these alkaloids were mainly accumulated in pith region and gradually decreased from pith to epidermis. Interestingly, three alkaloids were found to be present in higher abundance in the leaf vein. Along with the growth and development, the accumulation of these alkaloids was gradually increased in root and stem. Moreover, we employed LC-MS/MS to quantify three alkaloids and further validated the in situ distributions. The content of koumine reached 249.2 μg/g in mature roots, 272.0 μg/g in mature leaves, and 149.1 μg/g in mature stems, respectively, which is significantly higher than that of gelsemine and gelsenicine in the same organ. This study provided an accurately in situ visualization of gelsemine, koumine, and gelsenicine in G. elegans, and would be helpful for understanding their accumulation in plant and guiding application.