Effective receptors for fluoride and acetate ions: synthesis and binding study of pyrrole- and cystine-based cyclopeptido-mimetics

Two conformationally constrained pseudo-cyclopeptides (1, 2) consisting of pyrrole-, pyridine-, and cystine-moieties were designed and synthesized as neutral receptors for anionic guests. The anion recognition abilities of these two receptors were examined photometrically in acetonitrile solution. The UV-vis study revealed that the [1+1] receptor (1) formed 1:1 complexes with anions, whereas the [2+2] receptor (2) led to 1:2 mode binding with anions. Both receptors displayed good affinity and selectivity for fluoride and acetate ions.     

Transport behavior and efflux of Rg1 in rat pulmonary epithelial cells

The aim of this study was to investigate whether ginsenoside Rg1 could be transported into rat pulmonary epithelial cells and its transport behavior and efflux through the cells. A high-performance liquid chromatography coupled with 2487 UV-vis detector at 203 nm was applied. The mobile phase was 0.05% phosphate-acetonitrile (75:25, v/v). Cells were incubated with Rg1 (100 microg/mL) for a specific time, then lysed and sonicated in methanol to extract intracellular Rg1. Cells incubated with Rg1 and verapamil or KCN were processed by the same method. A 20 microL aliquot of sample was injected into the HPLC system to determine Rg1 concentration. The results showed that Rg1 could be transported into the epithelial cells with peak concentration of 1.28 microg/10(5) cells at 0.5 h. Metabolic inhibitor KCN and P-glycoprotein inhibitor verapamil could increase Rg1 concentration within the cells, indicating that efflux of Rg1 was energy-dependent and P-gp was likely to be involved. This is the first time that the transport behavior and efflux of Rg1 through rat pulmonary epithelial cells has been demonstrated. The phenomenon that Rg1 concentration in the cells decreased whereas that in the medium remained high indicated that a more effective means of drug administration should be found.     

Hydrogen bond assisted helical self-assembly into [n]catenane

A [n]catenane supramolecular structure has been constructed by combination of metal-directed self-assembly with interligand hydrogen bonds which were confirmed by H NMR and DFT calculation.     

Experimental Measurements for the QEC-Value of 183Os-Decay

Activities of ¹⁸³Os were produced by 39MeV α particles bombarding on a natural tungsten target.β⁺ spectrum with coincidence gate set on the strongest 382keV γ-rays of ¹⁸³Os decay was measured.The endpoint energy of the β⁺ spectrum was determined and the Q_EC value of ¹⁸³Os decay was extracted to be 2.24±0.10MeV which is in good agreement with the predicted value 2.30±0.10MeV on the basis of mass systematics.     

Burgers方程的交替分组显式迭代方法

从对流速度的物理意义出发,构造出求解Burgers方程的高精度交替分组显式迭代方法,并用线性化方法分析了其稳定性和收敛性,给出模型问题的数值结果。     

Network-Based Driving Force of National Economic Development: A Social Capital Perspective

Network science has been widely applied in theoretical and empirical studies of global value chain (GVC), and many related articles have emerged, forming many more mature and complete analytical frameworks. Among them, the GVC accounting method based on complex network theory is different from the mainstream economics in both research angle and content. In this paper, we build up global industrial value chain network (GIVCN) models based on World Input–Output Database, introduce the theoretical framework of Social Capital, and define the network-based indicators with economic meanings. Second, we follow the econometric framework to analyze the hypothesis and test whether it is true. Finally, we study how the three types of capital constituted by these indicators interact with each other, and discuss their impact on the social capital (economic development level, i.e., GDP). The results prove that the structural capital (industrial status) has a positive impact on the social capital; the relational capital (industrial correlation) has a positive impact on both social capital and structural capital; the cognitive capital (industrial structure) has a small impact on the social capital, structural capital, and relational capital.     

超大硅胺基氯锗宾的反应性与立方四锗卡宾的成键解析

超大硅胺基取代的低价锗化合物可以构建新颖的化学结构, 提供有学术价值的新发现。二配位的超大硅胺基氯锗宾Ge(N(SiⁱPr₃)₂)Cl (1)具有空的 4p轨道和孤电子对。针对这 2个特点, 研究了化合物 1 的热构型转换和菲醌氧化加成反应。1的温热分解生成了立方四锗卡宾 Ge₄(NSiⁱPr₃)₄ (2), 与菲醌(L)定量氧化加成生成了胺基一氯菲二酚合锗(Ⅳ):[Ge(N(SiⁱPr₃)₂)(L) Cl] (3)。表征了 2个产物的单晶结构与组成。四锗卡宾 2本质上是锗异腈的四聚体, 分子呈现出畸变的立方体构型, 4个 Ge原子和 4个N原子构成了中心立方体的 8个顶点。其中 Ge-N键长为 0.203 6(3) nm, N-Ge-N与 Ge-N-Ge的键角分别为 85.51(18)°和94.32(16)°, 立方体的侧面接近平行四边形。理论计算首次揭示了四锗卡宾 2的成键面貌。自然键轨道(NBO)给出 Ge₄N₄骨架上的 20个分子轨道。轨道定域化的计算结果完好地呈现出 4对 Ge孤对电子、12个 Ge-N键和 4个 Si-N键的定域轨道, 能量分别为-12.22、-15.12 和-20.12 eV。Ge 孤对电子主要保留了 4s 电子的特性, 而 Ge-N 键主要由 N 的 2s 轨道(18.4 %)和 2p 轨道(71.3 %)、Ge的 4s轨道(0.75 %)和 4p轨道(9.43 %)综合贡献形成。在化合物 3的分子中, Ge^Ⅳ采取 sp³杂化, 由于空间位阻与非对称配位, 与另外 4个配位原子形成非对称四面体构型。     

3D Printing of Capacitive Pressure Sensors with Tuned Wide Detection Range and High Sensitivity Inspired by Bio-Inspired Kapok Structures

Flexible pressure sensors have drawn considerable attention for their potential applications as electronic skins with both sensitivity and pressure response range. Although the introduction of surface microstructures effectively enhances sensitivity, the confined volume of their compressible structures results in a limited pressure response range. To address this issue, a biomimetic kapok structure is proposed and implemented for constructing the dielectric layer of flexible capacitive pressure sensors employing 3D printing technology. The structure is designed with easily deformable concave and rotational structures, enabling continuous deformation under pressure. This design results in a significant expansion of the pressure response range and improvement in sensitivity. Further, the study purposively analyses crucial parameters of the devised structure that affect its compressibility and stability. These include the concave angle θ, height ratio d₁/d₂, rotation angle α, and width k. As a result, the ultimate pressure sensors demonstrate remarkable features such as high sensitivity (≈2.38 kPa⁻¹ in the range of 0–10 kPa), broad detection range (734 kPa), fast response time (23 ms), and outstanding pressure resolution (0.4% at 500 kPa). This study confirms the viability of bionic structures for flexible sensors, and their potential to expand the scope of wearable electronic devices.     

航天光学遥感器像移速度矢计算数学模型

随着地面影像分辨力愈来愈高的要求,航天光学遥感器实时精确补偿摄影时地物产生的像移,已成为必需解决的关键技术之一。论述了航天光学遥感器在对星下点摄影时,通过建立从地面景物到像面的七个坐标系,进行14次线性变换,获得了具有15个参量的像面位置方程、像面速度方程,推导出像面上像移速度矢的计算公式,对影响像移速度矢的11个参量进行误差分配,以及应用蒙特卡罗法(统计试验法)进行误差综合。该理论方法已得到了实际应用,从获得的遥感图像达到的分辨力、奈奎斯特(Nyquist)频率处的传递函数、信噪比和平均灰度层次均充分证明了该研究结果的正确性。     

一类奇摄动微分——差分反应扩散方程

奇摄动问题有很强的自然科学的背景,它在生态环境、大气物理、海洋科学、催化反应、激波和量子物理中都有很广泛的应用.本文研究了一类带有小延迟的微分--差分反应扩散方程初值问题.在适当的条件下,利用奇摄动伸长变量法,构造了问题的形式渐近解.再用微分不等式理论证明了解的一致有效性.