绝缘衬底上硅表面载流子的超快动力学研究

利用800 nm波长的飞秒抽运探测技术测量r具有不同单晶硅薄膜厚度的绝缘衬底上硅(SOI)皮秒瞬态反射率变化,并通过基于受激载流子密度和温度变化过程建立的反射率模型讨论了SOI表面载流子的超快动力学过程.研究表明,表面复合速度(SRV)是影响载流子动力学响应的主要因素,且薄膜厚度越小表面复合速度就越大,对应的表面态密度可达到1013cm-2 .对于较小的SRV,受激载流子的超快响应决定了瞬念反射率变化;而对于较大的SRV,晶格温升对瞬态反射率变化的贞献变得显著,使得反射率在更短的时间内恢复并超过初始值.     

Spectroscopic Studies of the Stability of Doped Polythiophenes Under Air

Abstract

The stability of the doped state of conductive polythiophenes under air was investigated by the use of Infrared (IR) and UV-visible (UV) spectroscopies. Poly(3-methyl thiophene) doped with BF₃-ethyl ether (BFEE). shows higher stability due to its stereoregularity-chain structure. While the doped polythiophene (PT) degrades easily under the moisture.     

牛津型斯特林制冷机的失效分析方法

分析了牛津型斯特林制冷机的主要失效机理、参数表征及探测方法,提出了制冷机的失效分析方法和程序。该方法将用于80K/2W制冷机加速寿命试验后的失效分析,为确认其失效模式和机理提供依据。     

一种基于图像特征和神经网络的苹果图像分割算法

苹果识别是开发苹果采摘机器人的关键环节,利用图像处理技术和神经网络分类器探索苹果图像分割算法.从苹果树图片中选取苹果图像样本和背景网像样本.分别计算这两类图像样本的颜色特征和纹理特征.颜色特征的计算基于RGB色彩模型,纹理特征的计算基于灰度共生矩阵.选取适当的颜色特征(R/B值)和纹理特征(对比度值和相关性值)作为输入节点,利用反向传播神经网络分类器建模,输出值是一个O～1之间的计算值.通过阈值将输出结果分类为苹果或背景.试验结果表明,该算法正确率大于87.6%,对光照的影响不敏感,是一利较为实用的苹果分割算法.     

Non-Invasive Detection of Anti-Inflammatory Bioactivity and Key Chemical Indicators of the Commercial Lanqin Oral Solution by Near Infrared Spectroscopy

Quality control methods of current traditional Chinese medicine (TCM) preparation is time-consuming and difficult to assess in terms of overall efficiency of the drug. A non-destructive rapid near-infrared spectroscopy detection system for key chemical components and biological activity of Lanqin oral solution (LOS), one of the best-selling TCM formulations, was established for comprehensive quality evaluation. Near infrared spectral scanning was carried out on 101 batches of commercial LOS under the penetrated vial state and traditional state. RAW 264.7 cells were cultured to detect the anti-inflammatory ability of LOS, and the reference concentrations of epigoitrin, geniposide, and baicalin were obtained by HPLC. The quantitative models were optimized by three kinds of variable selection methods. The correlation coefficients of prediction value of the models were greater than 0.94. The system also passed the external validation. The performance of the non-invasive models was similar to the traditional models. The established non-destructive system can be applied to the rapid quality inspection of LOS to avoid unqualified drugs from entering the market and ensure drug effectiveness. The biological activity index of LOS was introduced and predicted by NIRs for the first time, which provides a new idea about the quality control of TCM formulations.     

Effects of Organic Acids on the Release of Fruity Esters in Water: An Insight at the Molecular Level

It is well known that organic acids (OAs) could affect the flavour of fruit juices and beverages. However, the molecular mechanism of aroma release is still unclear. In this study, the effects of citric acid (CA), L-(-)-malic acid (MA) and L-lactic acid (LA) on the release of six selected esters and their sensory perception were investigated by means of HS-GC-MS analyses and odour detection threshold determination, respectively. Meanwhile, the density functional theory (DFT) calculation was employed to explore the interaction modes between esters and OAs. HS-GC-MS analyses showed that the concentration and the type of OAs regulated the release of esters. The results were basically consistent with the detection threshold change of those esters. The DFT calculation suggested that the main intermolecular interaction was hydrogen bonds, and several esters could form a ternary ring structure with OAs through hydrogen bonds. The interactions can induce the different release behaviours of esters in OAs water solution. The number of carboxyl functional groups in OAs and the spatial conformation of esters appeared to influence the magnitude of the interaction. The above results demonstrated the mechanism of OAs affecting the release of esters and indicated a possible flavour control way by using different OAs and OA concentrations.     

全无机钙钛矿太阳电池的制备及稳定性

全无机钙钛矿太阳电池因其热稳定性好、载流子迁移率高,可用于制备叠层电池等优点备受关注.随着人们对全无机钙钛矿太阳电池的深入研究和制备工艺的持续优化,全无机钙钛矿太阳电池的光电转换效率已经突破19％.然而,全无机钙钛矿材料相稳定性较差,这使得实现全无机钙钛矿太阳电池在空气环境下制备和长期使用面临巨大挑战.众多科研工作者通...     

Engineering Plasmonic Environments for 2D Materials and 2D-Based Photodetectors

Two-dimensional layered materials are considered ideal platforms to study novel small-scale optoelectronic devices due to their unique electronic structures and fantastic physical properties. However, it is urgent to further improve the light–matter interaction in these materials because their light absorption efficiency is limited by the atomically thin thickness. One of the promising approaches is to engineer the plasmonic environment around 2D materials for modulating light–matter interaction in 2D materials. This method greatly benefits from the advances in the development of nanofabrication and out-plane van der Waals interaction of 2D materials. In this paper, we review a series of recent works on 2D materials integrated with plasmonic environments, including the plasmonic-enhanced photoluminescence quantum yield, strong coupling between plasmons and excitons, nonlinear optics in plasmonic nanocavities, manipulation of chiral optical signals in hybrid nanostructures, and the improvement of the performance of optoelectronic devices based on composite systems.     

Guajamers A-I,Rearranged Polycyclic Phloroglucinol Meroterpenoids from Psidium guajava Leaves and Their Antibacterial Activity

Main observation and conclusion Eight new polycyclic phloroglucinol meroterpenoids guajamers A-H (1-8),a methylated benzoylphloroglucinol meroterpenoid guajamer...     

Superhydrophobic Flexible Supercapacitors Formed by Integrating Hydrogel with Functional Carbon Nanomaterials

Main observation and conclusion With the rapid development of the wearable electronics,the flexible supercapacitor with high energy density has attracted more a...