Synthesis via a direct adsorption method and characterization of Cu<Superscript>2+</Superscript>-doped CdTe quantum-dot-sensitized TiO<Subscript>2</Subscript> nanotubes for use as a photoanode

A direct adsorption method for the synthesis of Cu²⁺-doped CdTe quantum dot (QD)-sensitized TiO₂ nanotubes (TNTAs) for use as a photoanode is reported in this study. The influences of the molar concentration of Cu²⁺, the sensitization temperature, the sensitization time, and the loop index on the photovoltaic performance of the CdTe:Cu²⁺/TNTAswas investigated. Scanning electron microscopy images showed that the CdTe:Cu²⁺ QDs are well dispersed on the TNTA surface. UV–vis adsorption measurements showed that the visible absorption of the TNTAs was enhanced by the CdTe:Cu²⁺ QD sensitization. Whereas the power conversion efficiency (PCE) of the bare TNTAs was 0.11%, the maximum PCE of the CdTe:5%Cu²⁺/TNTAs was 3.70% with a sensitization time of 5.0 h, a sensitization temperature of 60 °C, and a loop index of 2. Therefore, CdTe:5%Cu²⁺/TNTAs may be employed in quantum-dot-sensitized solar cells.

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Graphical abstract The conversion efficiency of the CdTe: 5%Cu²⁺/TiO₂ nanotube arrays can reach a maximum of 3.7%, which is enhanced by 33-fold, on comparison with bare TiO₂ nanotube arrays (0.11%).

     

Hilbert K-模上酉群的框架表示

本文主要研究了Hilbert K-模上酉群的框架表示的一些基本性质，联系框架的强不相交性，得到了Hilbert K-模上酉群的框架表示的重数是有限的．     

碳纤维三向织物/环氧树脂复合材料的制备与力学性能

选择不同纱线间距[即二经(纬)纱之间的中心距]尺寸的碳纤维三向织物,采用热压成型技术制备了碳纤维三向织物/环氧树脂复合材料.研究了纱线间距及样品裁剪角度等对力学性能的影响,并与碳纤维二向织物/环氧树脂复合材料的力学性能进行对比.结果表明,随着纱线间距尺寸从2 mm增加到6 mm,0°方向断裂强度从221. 7 MPa下降到148. 1 MPa,撕裂强力从1000 N下降到600 N; 90°方向断裂强度从50. 0MPa下降到22. 1 MPa,撕裂强力从330 N下降到100 N;顶破强力从424 N下降到216 N.这些力学性能的逐渐降低是单位面积的碳纤维增强体含量减少和织物的孔洞增大共同作用的结果.纱线间距为2 mm的碳纤维三向织物复合材料在0°(以纬纱为基准),30°,45°,60°和90°方向的断裂强度分别为221. 7,48. 5,44. 3,227. 7和50. 0 MPa,即断裂强度在0°和60°方向大于在30°,45°及90°方向.由三向织物的编织原理可知,0°与60°方向完全相同,因此其断裂强度相似,且样品中有一组纱线与外加载荷平行,对形变破坏具有一定的约束作用,而...     

Visible-Light Photocatalytic Reduction of Aryl Halides as a Source of Aryl Radicals

Aryl- and heteroaryl units are present in a wide variety of natural products, pharmaceuticals, and functional materials. The method for reduction of aryl halides with ubiquitous distribution is highly sought after for late-stage construction of various aromatic compounds. The visible-light-driven reduction of aryl halides to aryl radicals by electron transfer provides an efficient, simple, and environmentally friendly method for the construction of aromatic compounds. This review summarizes the recent progress in the generation of aryl radicals by visible-light-driven reduction of aryl halides with metal complexes, organic compounds, semiconductors as catalysts, and alkali-assisted reaction system. The ability and mechanism of reduction of aromatic halides in various visible light induced systems are summarized, intending to illustrate a comprehensive introduction of this research topic to the readers.     

Spatio-Temporal Dynamics of Entropy in EEGS during Music Stimulation of Alzheimer’s Disease Patients with Different Degrees of Dementia

Music has become a common adjunctive treatment for Alzheimer’s disease (AD) in recent years. Because Alzheimer’s disease can be classified into different degrees of dementia according to its severity (mild, moderate, severe), this study is to investigate whether there are differences in brain response to music stimulation in AD patients with different degrees of dementia. Seventeen patients with mild-to-moderate dementia, sixteen patients with severe dementia, and sixteen healthy elderly participants were selected as experimental subjects. The nonlinear characteristics of electroencephalogram (EEG) signals were extracted from 64-channel EEG signals acquired before, during, and after music stimulation. The results showed the following. (1) At the temporal level, both at the whole brain area and sub-brain area levels, the EEG responses of the mild-to-moderate patients showed statistical differences from those of the severe patients (p < 0.05). The nonlinear characteristics during music stimulus, including permutation entropy (PmEn), sample entropy (SampEn), and Lempel–Ziv complexity (LZC), were significantly higher in both mild-to-moderate patients and healthy controls compared to pre-stimulation, while it was significantly lower in severe patients. (2) At the spatial level, the EEG responses of the mild-to-moderate patients and the severe patients showed statistical differences (p < 0.05), showing that as the degree of dementia progressed, fewer pairs of EEG characteristic showed significant differences among brain regions under music stimulation. In this paper, we found that AD patients with different degrees of dementia had different EEG responses to music stimulation. Our study provides a possible explanation for this discrepancy in terms of the pathological progression of AD and music cognitive hierarchy theory. Our study has adjunctive implications for clinical music therapy in AD., potentially allowing for more targeted treatment. Meanwhile, the variations in the brains of Alzheimer’s patients in response to music stimulation might be a model for investigating the neural mechanism of music perception.     

Synthsis of 4‐Piperidones via Multicomponent Double Mannich Reaction Catalyzed by I2

A multicomponent double Mannich reaction of amines, aldehydes and ketones was efficiently catalyzed by molecular iodine, producing a series of 4‐piperidones in a stereoselective way. A variety of amines, aldehydes and ketones were tolerated in this tandem process, including those with labile functinal groups. Further investigation of the reaction between alkyl‐imines and ketones showed that imines from amines and ketones were formed in situ and isomerized to enamine in the presence of molecular iodine to accelerate the corresponding Mannich addition.     

Thermosensitive hollow Janus dumbbells

Thermosensitive hollow Janus dumbbells, consisting of two partially fused hollow poly (N-isopropylacrylamide) (PNIPAM) spheres, were prepared using dumbbell-shaped microgels as templates. One sphere has a shell completely made of PNIPAM while the other one has a hybrid shell, which is a poly(styrene-co-3-(trimethoxysilyl)propyl methacrylate) layer covered by PNIPAM. The morphology of hollow Janus dumbbells is fully characterized by cryo- and transmission electron microscopy, scanning force microscopy, and dynamic light scattering. Transmission electron microscopy demonstrates that the particles have a very narrow size distribution. The analysis by depolarized dynamic light scattering showed that the hollow Janus dumbbells exhibit a thermosensitive behavior comparable to the dumbbell-shaped microgels before the removal of the core.     

Rapid characterization of the constituents in Jigucao capsule using ultra high performance liquid chromatography with quadrupole time-of-flight mass spectrometry

Jigucao capsule is a well-known Chinese patent medicine for the treatment of acute and chronic hepatitis and cholecystitis. The chemical components of Jigucao capsule were not clear resulting from the paucity of relevant studies, which hindered the research of the pharmacological mechanism, the comprehensive development, and utilization of Jigucao capsule in clinical studies. By establishing a high-throughput ultra-performance liquid chromatography quadrupole time of flight mass spectrometry in combination with intelligent UNIFI software data processing platform to automatically characterize and identify the chemical profile of Jigucao capsule, 144 compounds were determined rapidly, including 34 terpenoids, 25 flavonoids, 22 steroids, 21 phenylpropanoids, 10 glycosides, six alkaloids, 13 organic acids, and other 13 components. These compounds may be the active components of Jigucao capsule. In this study, a rapid and robust method for comprehensively analyzing the chemical composition of Jigucao capsule was described and established for the first time. The results will provide a reference for the quality control of Jigucao capsule and the establishment of a higher quality standard, as well as for the pharmacodynamic material basis research.     

Approximation of the conductivity coefficient in the heat equation

In this paper, we study the conductivity coefficient determination in the heat equation from observation of the lateral Dirichlet-to-Neumann map. We define a bilinear form function Q_γ associated to the boundary condition and the Dirichlet-to-Neumann map, and prove that the linearized problem d?Q_γ is injective. Based on the idea of complex geometrical optics solutions, we give two approximations to the conductivity coefficient by using the Fourier truncation method and the mollification method. Under the a priori assumption of the conductivity, we estimate the errors between the conductivity coefficient and its approximations by setting a suitable bound of the frequency.