Use of generalized refined composite multiscale fractional dispersion entropy to diagnose the faults of rolling bearing

Nonlinear Dynamics - A typical symptom of vibration signals collected from rolling bearings with local faults is the existence of periodic transients, which makes the intrinsic structure of...     

A Mechanism of High-Tc Superconductivity Relating to Perovskite Crystal Structure

A mechanism of high-T_c superconductivity related to the perovskite crystal structure is proposed by a “phonon attenuation model”, which means that in the perovskite-like crystal structure, a number of “ordering” vacancies or holes occur due to the non-stoichiometric structure features. Such a reticular “spongly-like” structure facilitates lattice thermovibration attenuation perovskite (phonon attenuation) during temperature reduction. This leads to an abrupt drop of the resistivity, owing to the conduction electrons transmitted through the media without collision with irregularities in the lattice due to the lattice thermovibration. This probably is the main reason for high-T_c superconductivity of the perovskite cuprates.     

Syntheses,crystal structures and properties of Cd(II) and Ag(I) complexes based on 2-p-methylphenyl-5-(2-pyridyl)-1,3,4-thiadiazole

Abstract

Complexes of [CdL₂(NO₃)₂]·1.5H₂O and [Ag₂(μ-L)₂(NO₃)₂] were synthesized by the reactions of 2-p-methylphenyl-5-(2-pyridyl)-1,3,4-thiadiazole (L) with Cd(NO₃)₂·4H₂O and AgNO₃, respectively. Their structures were determined by single crystal X-ray diffraction. The photophysical property and thermal stability were characterized by FT???IR, UV???Vis absorption, fluorescence, and thermogravimetric analysis (TGA). Both complexes belong to the triclinic system with space group p???1. The central metal of [CdL₂(NO₃)₂]·1.5H₂O has a distorted octahedral geometry [CdN₄O₂], while two central Ag(I) atoms of [Ag₂(μ-L)₂(NO₃)₂] exhibit distorted tetrahedral geometries [AgN₃O].     

Guanidine-based task-specific ionic liquids as catalysts for aza-Michael addition under solvent-free conditions

An efficient and facile protocol for aza-Michael addition of aliphatic and aromatic amines to electron-deficit alkenes using [TMG][Lac] as catalyst under solvent-free conditions was established.     

3-胺基取代苯并吡喃酮类化合物的设计合成及抗肿瘤活性

根据生物电子等排原理, 设计并合成了一系列新颖的3-胺基取代苯并吡喃酮类化合物. 通过1H NMR, 13C NMR, MS, IR及元素分析确定其结构. 抗肿瘤活性测试结果表明, 部分该系列化合物对人结肠癌细胞株HCT116和人肝癌细胞株7721具有较好的抑制活性, 其中化合物6c, 6f, 6i, 6m和6o对人肝癌细胞株7721的半数抑制浓度(IC50)值均小于对照品姜黄素(IC50＝10.53 μmol•L－1), 化合物6f对人结肠癌细胞株HCT116和人肝癌细胞株7721的IC50值分别为5.57和4.92 μmol•L－1, 均小于姜黄素的相应值.     

In situ X-ray diffraction study of reduction processes of Fe3O4- and Fe1−xO-based ammonia-synthesis catalysts

The temperature-programmed reduction process of two types of industrial ammonia-synthesis catalysts, A110 and ZA-5, which are, respectively, based on Fe₃O₄ and Fe_1−xO precursors, were studied by in situ X-ray power diffraction (XRD). It has been found that the ZA-5 has lower reduction temperature and faster reduction rate, and its active phase α-Fe possesses a higher value of lattice microstrain than A110. The simulation based on Rietveld refinement has also shown that the shape of α-Fe grain of ZA-5 has a mixed shape of cube and sphere with more exposing (111) and (211) planes, while that of A110 looks like a concave cube with more exposing (110) planes. Based on the results obtained, a growth model of α-Fe during the reduction of Fe₃O₄- and Fe_1−xO-based ammonia-synthesis catalysts is proposed, and the origins for the activity difference has been also discussed.     

Enantioselective synthesis of beta-aryl-gamma-amino acid derivatives via Cu-catalyzed asymmetric 1,4-reductions of gamma-phthalimido-substituted alpha,beta-unsaturated carboxylic acid esters

A series of chiral beta-aryl-substituted gamma-amino butyric acid derivatives were synthesized in good enantioselectivities via the Cu-catalyzed asymmetric conjugate reduction of gamma-phthalimido-alpha,beta-unsaturated carboxylic acid esters using Cu(OAc)2 x H2O as a catalyst precursor, (S)-BINAP as a ligand, PMHS as a hydride source, and t-BuOH as an additive. The methodology has been applied successfully to the enantioselective synthesis of a chiral pharmaceutical, (R)-baclofen.     

用于农药残留检测的酶生物传感器

酶生物传感器在农药残留检测方面具有传统检测方法不可比拟的优势.本文介绍了胆碱酯酶和有机磷水解酶在生物传感器中的应用,重点介绍了用于有机磷等农药残留分析的酶生物传感器的种类和研究现状,讨论了几种酶固定化方法存在的优势和局限,指出了目前研究需解决的问题并展望了未来的发展方向.     

以萘酰亚胺衍生物基荧光高分子为载体和指示剂的 相分离免疫分析方法

以4-甲氧基-N-(2-N’,N’-二甲基氨基乙基-N’-烯丙基)萘二甲酰亚胺氯化铵(DMNAA)为荧光单体, 合成了一种pH敏感荧光高分子聚N-异丙基丙烯酰胺-4-甲氧基-N-(2-N’,N’-二甲基氨基乙基-N’-烯丙基)萘二甲酰亚胺氯化铵-N,N-二甲基氨丙基甲基丙烯酰胺[P(NIP-DMAPM-DMNAA)]. 采用共聚法将日本血吸虫抗原(SjAg)固定在P(NIP-DMAPM-DMNAA)上, 制备P(NIP-DMAPM-DMNAA)-SjAg连接物, 与日本血吸虫抗体(待测, SjAb)发生免疫反应后, 调节pH值, 使荧光高分子相变分离高分子-免疫组分连接物, 最后, 利用蛋白A对抗体的亲和性捕获P(NIP-DMAPM-DMNAA)-SjAg-SjAb, 通过测定高分子自身的荧光信号来定量 SjAb. 该新型高分子具有良好的荧光特性, 对pH响应快速, 37 ℃下相转变pH值为7.2, 分离免疫复合物时造成的损害低. 与传统相分离免疫分析比较, 新方法通过高分子相变分离和蛋白A捕获双重分离作用, 消除了非特异性组分和未反应的特异性免疫成分等的干扰; 利用高分子自身的荧光信号检测, 无须另外的标记物, 大大提高了免疫分析的简便性. 以日本血吸虫抗体为分析对象, 测得线性范围为1～1500 ng/mL, 抗体检出限为1.3 ng/mL, 相对标准偏差为3.6% (n＝10), 结果令人满意.