The Rise of Fiber Electronics

As a new direction in applied chemistry, fiber electronics allow device configuration to evolve from three to two dimensions and then to one dimension. The reduction in dimension brings unique properties, such as ultraflexibility, tissue adaptability, and weavability, enabling their use in a variety of applications, particularly in various emerging fields related to implantable devices and wearable systems. The different types of fiber electrode materials are summarized based on the one‐dimensional configuration and their distinctive interfaces, various devices, and promising applications. The remaining challenges and future directions are finally highlighted.     

热脱附-气相色谱-质谱法测定稀土萃取分离车间固定污染源废气中18种挥发性有机化合物的含量北大核心CSCD

提出了热脱附-气相色谱-质谱法测定稀土萃取分离车间固定污染源废气中18种挥发性有机化合物(VOCs,包括1,1-二氯乙烷、1,2-二氯乙烯、1,1,2-三氯乙烷、甲苯、1,2,4-三甲基苯、苯、三氯乙烯、四氯乙烯,C_(7)~C_(16)等10种正构烷烃)含量。将采样器与2只串联的吸附管(装载有2种石墨化碳黑和1种碳分子筛)连接,于固定污染源排气口以50~65 mL·min^(-1)采样速率采集样品50 mL,密封吸附管,置于热脱附仪上,按照优化的仪器工作条件测定收集的气体中的18种VOCs含量(苯和四氯乙烯含量为2只吸附管吸附量的加和)。吸附管和聚焦冷阱的脱附温度均设置为350℃,脱附时间均设置为10 min。结果显示,10种正构烷烃标准曲线的线性范围为50.0~400 ng,其他8种VOCs的质量在20.0~300 ng内与其对应的峰面积与内标物峰面积的比值呈线性关系,检出限(3s)为0.0015~0.026 mg·m^(-3)。对空白样品进行3个浓度水平的加标回收试验,18种VOCs的回收率为73.5%~110%,测定值的相对标准偏差(n=5)为1.2%~22%。4家实验室同时采用以上方法分析空白加标样品,偏差的绝对值均小于参考HJ 168-2010计算所得的再现性限。     

A nonlinear third order multi-point boundary value problem in the resonance case

In this paper, we discuss the following third order ordinary differential equation $$x^{\prime\prime\prime}(t)=f(t,x(t),x^{\prime}(t),x^{\prime\prime}(t))+e(t),\quad t\in (0,1)$$ with the multi-point boundary conditions $$x^{\prime}(0)=\alpha x^{\prime}(\xi),\qquad x^{\prime\prime}(0)=0,\qquad x(1)=\sum^{m-2}_{j=1}\beta_{j}x(\eta_{j})$$ where β _j (1≤j≤m?2), α∈R, 0<η ₁<η ₂<???<η _m?2<1, 0<ξ<1. When the β _j ’s have no same sign, some existence results are given for the nonlinear problems at resonance case. An example is provided in this paper.     

Synthesis, structure, and chemistry of new, mixed group 14 and 16 heterocycles: nucleophile-induced ring contraction of mesocyclic dications

More than 40 new 4- to 12-membered ring heterocycles containing various combinations of Group 14 and 16 elements Si, Sn, S, Se, and Te have been synthesized and fully characterized. Synthesis of these small-ring as well as medium-ring (mesocyclic) heterocycles from alpha,omega-dihalides is facilitated by the presence of gem-dialkylsilyl and gem-dialkylstannyl groups in the precursors. Conformations of several of the new ring systems in the solid state have been determined by X-ray crystal structure analysis. Oxidation of mixed S(Se, Te)/Si eight-membered ring mesocycles with NOPF6 or Br2 gives dications or a bicyclic dibromide, respectively, which can be characterized by NMR methods. On treatment with nucleophiles, mesocyclic dications, or the corresponding radical cations undergo ring contraction, giving five- or six-membered ring heterocycles. Photolysis of a S/Se four-membered ring heterocycle gives selenoformaldehyde, trapped in 80% yield with 2,3-dimethyl-1,3-butadiene.     

Synthesis and characterization of soluble oligo (9,10-bisalkynylanthrylene)s

[structure: see text] Soluble oligo(9,10-bialkynylanthrylene)s up to pentamers were synthesized by means of the Suzuki coupling reaction. A solution processed thin film field-effect transistor from pentamer OA-5b shows a charge carrier mobility of 2.95 x 10(-)(3) cm(2)/V x s.     

基于单目视觉的SLAM算法研究

利用一种新型的人工路标系统-MR二维码,提出了基于单目视觉和里程计的SLAM方法.首先介绍了MR二维码系统,然后在对机器人运动模型和视觉传感器观测模型进行分析和验证的基础上,给出了一种实用的里程计位置估计误差模型.机器人移动过程中,利用扩展卡尔曼滤波器对视觉信息与里程计信息进行融合.在室内环境下进行了实际实验,实验结果表明该算法可提高机器人定位和构建地图的精度,验证了算法的有效性.     

A surface-imprinted polymer for removing dibenzothiophene from gasoline

A surface-imprinted polymer for the adsorption of dibenzothiophene (DBT) was obtained from DBT (the template), titanium dioxide (the support), methacrylic acid (the functional monomer), ethylene glycol dimethacrylate (the cross-linker), 2,2´-azobisisobutyronitrile (the initiator) and toluene (the porogen). The material was characterized by Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller model and Scanning electron microscopy. Batch adsorption experiments were performed to study the adsorption of the material in terms of adsorption kinetics, isotherms, and thermodynamic parameters. The adsorption follows pseudo-second-order kinetics, the Freundlich adsorption equation fits the experimental data well, and there is strong evidence for multiple layer adsorption. The negative values of the Gibbs free energy (ΔG₀) range from -6.04 kJ?mol^-1 to -7.69 kJ?mol^-1 between 298 and 318 K, which reveals that the adsorption is endothermic. The material can selectively recognize DBT over similar compounds present in gasoline (such as benzothiophene and 4-methyldibenzothiphene).     

简化的系统搜索法及其在构象分析中的应用

多肽的构象研究除了可以用X-射线晶体学及二维核磁共振等实验方法外,理论计算的方法有系统搜索法、蒙特卡洛方法、距离几何方法、分子动力学方法及能量极小化等.系统搜索法具有构象空间搜索彻底的特点,相对来说找到系统整体极小值的可能性较大,但由于其计算量较大,对于多肽及蛋白质很难实现.我们对系统搜索法进行了简化,不是同时旋转所有的二面角,而是成对地进行,以迭代的方法达到收敛,最后得到可能的构象.     

New Born radii deriving method for Generalized Born model

Here we report a method to calculate Born radii, an important parameter used in a Generalized Born model. Traditional methods to derive Born radii are mostly based on a complicated formula, while our method is easier and more direct. Atoms are classified according to their atom type, and the Born radii of each type are obtained by fitting to experimental solvation free energy. The SMARTS language is used for the exact definition of atoms types, and Ullmann's subgraph isomorphism algorithm is used to deduce the environment. A generic algorithm is used for the parameter fitting because of its efficiency in searching a huge phase space, and its results are then optimized by using the conjugate gradient method. The final parameter set is fitting from a training set containing 357 molecules and is tested using a test set of 44 small organic molecules, and the average error is 0.58 kcal/mol for 36 neutral molecules and is 1.67 kcal/mol for 8 ions. The model is further tested under organic molecules, biopolymers, and a protein-inhibitor complex and yields reliable results in all these cases. This method can be used to accelerate molecular docking calculations.