Asymmetric Synthesis of a Fused Tricyclic Hydronaphthofuran Scaffold by Desymmetric [2+2+2] Cycloaddition

A rhodium(I)‐BINAP‐catalyzed highly enantioselective [2+2+2] cycloaddition of enynes with alkynes has been developed. Diverse fused tricyclic hydronaphthofuran scaffolds with three consecutive stereogenic centers were constructed in one step from easily available materials with excellent chemo‐, regio‐, diastereo‐, and enantioselectivity. Notable features of these reactions include 100 % atom economy, very broad scope, and mild reaction conditions.     

“金属的电化学腐蚀”教学设计创新

以学科理解为基础,注重创设真实的教学情境,创新实验设计,使学生在探究暖贴发热原理和钢铁腐蚀原理的过程中获得金属电化学腐蚀的知识,拓展认知结构,学习科学方法,发展科学探究能力。     

Screening of drugs of abuse and toxic compounds in human whole blood using online solid‐phase extraction and high‐performance liquid chromatography with time‐of‐flight mass spectrometry

A novel method for the screening of 151 drugs of abuse and toxic compounds in human whole blood has been developed and validated by online solid‐phase extraction with liquid chromatography coupled to time‐of‐flight mass spectrometry. Analytes were extracted and separated by using a fully automated online solid‐phase extraction liquid chromatography system with total chromatographic run time of 26 min. Time‐of‐flight mass spectrometry screening of 151 drugs of abuse and toxic compounds was performed in a full‐scan (m/z 50–800) mode using an MS^E acquisition of molecular ions and fragment ions data at two collision energies (one was 6 eV and another one was in the range of 5–45 eV). The compounds were identified based on retention times and exact mass of molecular ions and fragment ions. The limit of detection ranged from 1 to 100 ng/mL and the recovery of the method ranged from 6.3 to 163.5%. This method is proved to be a valuable screening method allowing fast and specific identification of drugs in human whole blood.     

Mo掺杂Mn4Si7的光电性质的第一性原理计算

采用基于密度泛函理论(DFT)的第一性原理计算方法,计算了Mn4Si7及Mo掺杂Mn4Si7的电子结构和光学性质.计算结果表明Mn4 Si7的禁带宽度Eg=0.804 eV,Mo掺杂Mn4Si7的禁带宽度Eg=0.636 eV.掺杂使得Mn4 Si7费米面附近的电子结构发生改变,导带底由Γ点转移为Y点向低能方向下偏移,价带顶向高能方向上偏移,带隙变窄.计算还表明Mo掺杂Mn4Si7使介电函数、折射率、吸收系数及光电导率等光学性质增加.     

低渗透油藏爆炸压裂产能分析及压裂改造区域优化设计

基于爆炸压裂裂缝分布规律,提出爆炸压裂缝网双重介质复合流动产能模型,应用Laplace变换Stehfest数值反演,得到了定压条件下封闭外边界低渗透油藏爆炸压裂生产井产能表达式。在模型正确性验证的基础上结合某低渗透油藏储层特征参数研究了爆炸压裂改造区域参数对封闭边界油藏产量的影响,同时对爆炸压裂改造改造体积优化设计进行了研究。研究结果表明,爆炸压裂改造区域半径主要影响生产中期产能,改造区域渗透率对生产早期和中期影响比较大,且对于实例油藏爆炸压裂改造比为0.1时效果最好。     

The global dimensions of crossed products and crossed coproducts

In this paper, we show that if H is a finite-dimensional Hopf algebra such that H and H^＊ are semisimple, then gl.dim（A#σH）=gl.dim（A）, where a is a convolution invertible cocycle. We also discuss the relationship of global dimensions between the crossed product A^#σH and the algebra A, where A is coacted by H. Dually, we give a sufficient condition for a finite dimensional coalgebra C and a finite dimensional semisimple Hopf algebra H such that gl.dim（C α H）=gl.dim（C）.     

Carbon nitride with encapsulated nickel for semi-hydrogenation of acetylene: pyridinic nitrogen is responsible for hydrogen dissociative adsorption

A new mechanism of catalyst has been demonstrated in this article. With the interaction between carbon nitride (CN) and encapsulated nickel, the CN in the catalyst has been endowed with new active sites for the adsorption and activation of hydrogen while nickel itself is physically isolated from the contact with reactive molecules. For the selective hydrogenation of acetylene in large amount of ethylene, the catalyst shows excellent ethylene selectivity than the nickel catalyst itself, which is almost totally unselective. Meanwhile, the CN itself is inactive for the reaction. The results of characterization demonstrate that pyridinic nitrogen doped in the carbon matrix should be the active sites for hydrogen dissociative adsorption. The theoretical calculations further confirm the results and provide with the detail in the electron transfer between nickel and CN in the catalyst. The current results supply a new concept for design of high performance catalyst.     

Permanence of the nonautonomous competitive systems with infinite delay and feedback controls

We study the permanence of a class of nonautonomous two-species Lotka–Volterra competitive systems with infinite delay and feedback controls. New results on the permanence of solutions are obtained. The corresponding results given in [F. Chen, Z. Li, Y. Huang, Note on the permanence of a competitive system with infinite delay and feedback controls, Nonlinear Anal. RWA 8 (2007) 680–687] are improved and extended.     

Design and fabrication of subwavelength nanogratings based light-emitting diodes

Linearly polarized light from InGaN green light emitting diode grown on (0001) oriented sapphire is demonstrated by using subwavelength metallic nanogratings. Polarization ratio can reach 7:1 (∼88%), the highest ever reported from a single light emitting device. We discuss the design and fabrication of this device in detail.