Multi-Label Feature Selection Combining Three Types of Conditional Relevance

With the rapid growth of the Internet, the curse of dimensionality caused by massive multi-label data has attracted extensive attention. Feature selection plays an indispensable role in dimensionality reduction processing. Many researchers have focused on this subject based on information theory. Here, to evaluate feature relevance, a novel feature relevance term (FR) that employs three incremental information terms to comprehensively consider three key aspects (candidate features, selected features, and label correlations) is designed. A thorough examination of the three key aspects of FR outlined above is more favorable to capturing the optimal features. Moreover, we employ label-related feature redundancy as the label-related feature redundancy term (LR) to reduce unnecessary redundancy. Therefore, a designed multi-label feature selection method that integrates FR with LR is proposed, namely, Feature Selection combining three types of Conditional Relevance (TCRFS). Numerous experiments indicate that TCRFS outperforms the other 6 state-of-the-art multi-label approaches on 13 multi-label benchmark data sets from 4 domains.     

Superhydrophobicity on two-tier rough surfaces fabricated by controlled growth of aligned carbon nanotube arrays coated with fluorocarbon

Considerable effort has been expended on theoretical studies of superhydrophobic surfaces with two-tier (micro and nano) roughness, but experimental studies are few due to the difficulties in fabricating such surfaces in a controllable way. The objective of this work is to experimentally study the wetting and hydrophobicity of water droplets on two-tier rough surfaces for comparison with theoretical analyses. To compare wetting on micropatterned silicon surfaces with wetting on nanoscale roughness surfaces, two model systems are fabricated: carbon nanotube arrays on silicon wafers and carbon nanotube arrays on carbon nanotube films. All surfaces are coated with 20 nm thick fluorocarbon films to obtain low surface energies. The results show that the microstructural characteristics must be optimized to achieve stable superhydrophobicity on microscale rough surfaces. However, the presence of nanoscale roughness allows a much broader range of surface design criteria, decreases the contact angle hysteresis to less than 1 degrees , and establishes stable and robust superhydrophobicity, although nanoscale roughness could not increase the apparent contact angle significantly if the microscale roughness dominates.     

人工神经网络紫外分光光度法测定息喘灵片多组分体系的研究

介绍了人工神经网络（ＡＮＮ）原理，详细讨论了网络参数的选择及其对预报的影响。将该技术应用于息喘灵片三组分体系的预报测定并取得满意结果。     

Preparation of cellulose nano-crystals through a sequential process of cellulase pretreatment and acid hydrolysis

In this paper, a cellulase pretreatment was studied prior to the acid hydrolysis to decrease the total acid usage during the cellulose nano-crystals (CNC) preparation from a bleached softwood kraft pulp. Cellulase pretreatment facilitates the subsequent acid hydrolysis to produce CNC with similar quality to that of the control, but at a lower sulfuric acid concentration. The underline mechanism is that cellulase pretreatment led to the formation of more carbonyl groups which can be oxidized into carboxyl groups in the subsequent acid hydrolysis, furthermore, more hydroxyl groups are exposed, thus esterification into sulfonic groups can be enhanced. The results showed that with a cellulase dosage of 4.8 u/g (based on dry pulp) in the pretreatment stage, the sulfuric acid concentration can be decreased from 64 to 40 wt% without compromising the quality of resulting CNC particles. Other results from charge properties, Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM) analyses also supported the conclusions.     

Pressure-induced semiconductor–metal phase transition in Mg2Si

In situ electrical resistivity measurement of powdered Mg₂Si has been performed in a diamond anvil cell up to 25.4 GPa. At about 22.2 GPa, Mg₂Si underwent a pressure-induced semiconductor–metal phase transition that took place in the Ni₂In-type structure rather than the anti-fluorite structure predicted theoretically. The other phases (anti-fluorite and anti-cotunnite) belong to the semiconductor phase.     

Bimetallic Cyclometalated Iridium(III) Diastereomers with Non‐Innocent Bridging Ligands for High‐Efficiency Phosphorescent OLEDs

Two phosphorescent dinuclear iridium(III) diastereomers (ΛΔ/ΔΛ) and (ΛΛ/ΔΔ) are readily separated by making use of their different solubilities in hot hexane. The bridging diarylhydrazide ligand plays an important role in the electrochemistry and photophysics of the complexes. Organic light‐emitting devices (OLEDs) that use these complexes as the green‐emissive dopants in solution‐processable single‐active‐layer architectures feature electroluminescence efficiencies that are remarkably high for dinuclear metal complexes, achieving maximum values of 37 cd A^?1, 14 lm W^?1, and 11 % external quantum efficiency.     

Stimuli-Responsive Luminescent Properties of Tetraphenylethene-Based Strontium and Cobalt Metal–Organic Frameworks

Herein we report two new TPE-based 3D MOFs, that is, Sr-ETTB and Co-ETTB (TPE=Tetraphenylethylene, H₈ETTB=4′,4′′′,4′′′′′,4′′′′′′′-(ethene-1,1,2,2-tetrayl)tetrakis(([1,1′-biphenyl]-3,5-dicarboxylic acid))). Through tailoring outer shell electron configurations of Sr^II and Co^II cations, the fluorescence intensity of the MOFs is tuned from high emission to complete non-emission. Sr-ETTB with strong blue fluorescence shows reversible fluorescence variations in response to pressure and temperature, which is directly related to the reversible deformation of the crystal structure. In addition, non-emissive Co-ETTB counterpart exhibits a turn-on fluorescent enhancement under the stimulation of analyte histidine. In the process, TPE-cored linkers in the MOFs are released through competitive coordination substitution and subsequently reassembled to perform aggregation-induced luminescence behavior originated from the organic linkers.     

氧碘化学激光高反射薄膜的性能研究

通过实际测量和理论计算,给出高反射薄膜的散射和吸收数据,分析两种损耗对薄膜性能起的不同作用;同时,还讨论了热处理对薄膜吸收的影响.     

Preparation and fluorescence properties of Yb3+ and Er3+ co-doped GdAlO3 phosphors

Yb³⁺ and Er³⁺ co-doped GdAlO₃ phosphors are prepared by the sol–gel method. The effect of doping concentration on the structure and fluorescence properties is investigated by X-ray diffraction (XRD) and photoluminescence, respectively. XRD pattern indicates that the sample structure belongs to orthorhombic. The photoluminescence results show that both green and red fluorescence emission and upconversion emission intensities decrease with an increase in Yb³⁺ concentration due to the cross-relaxation process between Yb³⁺ and Er³⁺ ions. Based on the emission spectra, the mechanism of the upconversion emission is discussed, and we concluded that the upconversion emission is a two-photon process.