Far-field intensity distribution, M factor of beams generated by Gaussian mirror resonator

We investigated M² factor and far-field distribution of beams generated by Gaussian mirror resonator. And we found usable analytical expressions of the M² factor and the far-field distribution intensity with respect to variation of diffraction parameters. Particular attention was paid to the parameters such as mirror spot size and reflectance of the Gaussian mirror.     

Positive solutions for a system of nonlinear singular Hammerstein integral equations via nonnegative matrices and applications

We are concerned with the existence and multiplicity of positive solutions for the system of nonlinear singular Hammerstein integral equations $$u_i(t)=\int_a^bk_i(t,s)g_i(s)f_i(s,u_1(s),\ldots,u_n(s)) {\rm d} s,\quad i=1,2,\ldots,n.$$ We use fixed point index theory to establish our main results based on a priori estimates achieved by utilizing nonnegative matrices. As applications, the main results are applied to establish the existence and multiplicity of positive solutions for an elliptic system in an annulus.     

Evidence for inhibition of HIF-1α prolyl hydroxylase 3 activity by four biologically active tetraazamacrocycles

Hypoxia inducible factor 1 (HIF-1) is central to the hypoxic response in mammals. HIF-1α prolyl hydroxylase 3 (PHD3) degrades HIF through the hydroxylation of HIF-1α. Inhibition of PHD3 activity is crucial for up-regulating HIF-1α levels, thereby acting as HIF-dependent diseases therapy. Macrocyclic polyamines which display high stability on iron-chelating may well inhibit the enzyme activity. Thus inhibition and interaction on catalytic PHD3 by four biologically active tetraazamacrocycles (1-4), which have two types of parent rings to chelate iron(ii) dissimilarly, were studied. The apparent IC(50) values of 2.56, 1.91, 5.29 and 2.44 μM, respectively, showed good inhibition potency of the four compounds. K(I) values were 7.86, 3.69, 1.59 and 2.92 μM for 1-4, respectively. Different inhibition actions of the two groups of compounds were identified. Circular dichroism (CD) and fluorescence spectrometries proved that one type of compound has significant effects on protein conformation while another type does not. Computational methodology was constructed to employ the equilibrium geometry of enzyme active site with the presence of substrate competitive inhibitor. Iron(ii) coordination in the active site by inhibitors of this kind induces conformational change of the enzyme and blocks substrate binding.     

Promoted Fixation of Molecular Nitrogen with Surface Oxygen Vacancies on Plasmon‐Enhanced TiO2 Photoelectrodes

A hundred years on, the energy‐intensive Haber–Bosch process continues to turn the N₂ in air into fertilizer, nourishing billions of people while causing pollution and greenhouse gas emissions. The urgency of mitigating climate change motivates society to progress toward a more sustainable method for fixing N₂ that is based on clean energy. Surface oxygen vacancies (surface O_vac) hold great potential for N₂ adsorption and activation, but introducing O_vac on the very surface without affecting bulk properties remains a great challenge. Fine tuning of the surface O_vac by atomic layer deposition is described, forming a thin amorphous TiO₂ layer on plasmon‐enhanced rutile TiO₂/Au nanorods. Surface O_vac in the outer amorphous TiO₂ thin layer promote the adsorption and activation of N₂, which facilitates N₂ reduction to ammonia by excited electrons from ultraviolet‐light‐driven TiO₂ and visible‐light‐driven Au surface plasmons. The findings offer a new approach to N₂ photofixation under ambient conditions (that is, room temperature and atmospheric pressure).     

Electroluminescence characteristics of organic thin film pumped by pulsed excitation

The current roll-off in organic light-emitting diodes has been studied by observing the current density versus voltage characteristics and spectra of single-layer and bilayer devices. Pumped by radiation sources of a variety of intensities, the current densities in a single-layer device decrease and spectra were shifted towards blue region. This is a result of the large amount of excess anion radicals that absorb the emitted photons. Using a bilayer device to balance the excess anion radicals is one of the methods to restrain the current roll-off.     

含嘧啶环的双冠醚——V.双冠醚为载体的碱金属离子选择性电极的研究

本文报道由5-硝基-6-三氟甲基嘧啶环桥联苯并-12-冠-4、苯并-15-冠-5和苯并-18-冠-6的三种新的双冠醚的合成。用它们作为载体分别制成钠、钾和铯离子选择性电极，测定了电极的响应功能、选择性系数和适用的pH范围。结果表明三种电极都有较好的性能。     

高效液相色谱法测定人血浆中甲磺酸培氟沙星浓度

建立了一种测定人血浆中甲磺酸培氟沙星的匠相液相色谱方法,用的是ＺｏｒｂａｘＯＤＳＣ＿（１８）柱和用三乙醇胺调节成ｐＨ为３．０的甲醇－０．０４ｍｏｌ／ＬＨ＿３ＰＯ＿４溶液（８０：２０,Ｖ／Ｖ）的流动相,检测在２７６ｎｍ处进行,流量为１ｍＬ／ｍｉｎ,线性范围是６．０１×１０￣（－８）～３．０１×１０￣（－５）ｍｏｌ／Ｌ（γ＝０．９９９８）,检测极限为６．０１×１０￣（－８）ｍｏｌ／Ｌ,平均回收率为９７．５７±３．０４％,日内与日间的ＣＶ分别为３．２９％和５．０８％。     

Modulating Benzothiadiazole-Based Covalent Organic Frameworks via Halogenation for Enhanced Photocatalytic Water Splitting

Two-dimensional covalent organic frameworks (2D COFs), an emerging class of crystalline porous polymers, have been recognized as a new platform for efficient solar-to-hydrogen energy conversion owing to their pre-designable structures and tailor-made functions. Herein, we demonstrate that slight modulation of the chemical structure of a typical photoactive 2D COF (Py-HTP-BT-COF) via chlorination (Py-ClTP-BT-COF) and fluorination (Py-FTP-BT-COF) can lead to dramatically enhanced photocatalytic H₂ evolution rates (HER=177.50 μmol h⁻¹ with a high apparent quantum efficiency (AQE) of 8.45 % for Py-ClTP-BT-COF). Halogen modulation at the photoactive benzothiadiazole moiety can efficiently suppress charge recombination and significantly reduce the energy barrier associated with the formation of H intermediate species (H*) on polymer surface. Our findings provide new prospects toward design and synthesis of highly active organic photocatalysts toward solar-to-chemical energy conversion.     

用L-脯氨酸衍生物作为手性流动相添加剂拆分对映异构体

用自制的N-十二酰基-L-脯氨酸和N-十二酰基-L-脯氨酸-3,5-二甲基苯胺两种L-脯氨酸衍生物作手性流动相添加剂,在氨丙基硅烷化硅胶柱上,用正己烷/异丙醇作流动相,对多种手性化合物进行了高效液相色谱拆分.实验结果表明用N-十二酰基-L-脯氨酸作添加剂拆分的12种手性化合物,有8种手性化合物能得到拆分,具有较好的手性选择性.虽然用N-十二酰基-L-脯氨酸-3,5-二甲基苯胺作添加剂,手性选择性也较好,但由于含有苯环,紫外吸收增强,基线波动严重.     

含有氢键供体大环化合物的构筑及其功能研究进展

含有氢键供体基团构筑的大环化合物因其结构中具有可以提供氢键供体的N—H基团,可以为大环化合物的主客体化学提供额外的分子间作用力,在分子识别、自组装以及超分子催化等领域被广泛应用.综述了近十年基于(硫)脲键、酰胺键构筑的大环化合物的合成方法及其在分子识别中的最新研究进展.为今后此类大环化合物的合成及应用提供参考.