From mushroom alcohol to liquid crystals: a useful platform molecule

The syntheses and liquid crystal properties of two novel esters derived from 4-(4-(decyloxy)phenyl)thiophene-2-carboxylic acid and either (±)-oct-1-en-3-yl 4?-hydroxybiphenyl-4-carboxylate or (S)-(+)-oct-1-en-3-yl 4?-hydroxybiphenyl-4-carboxylate are reported. Within the synthesis of the (S)-(+)-oct-1-en-3-yl 4?-hydroxybiphenyl-4-carboxylate, mushroom alcohol, a natural source of chiral oct-1-en-3-ol and a platform molecule, was employed. The phases present within these compounds have been characterised by thermal optical polarising microscopy and differential scanning calorimetry and assigned as SmA, SmC and SmC Alt for the racemic compound and; SmA, SmC* and SmC*_A for the enantiomerically pure compound. This is first reported occurrence of a liquid crystalline ester derived from mushroom alcohol, and potential platform molecule, exhibiting SmA*, SmC* and SmC*_A phases.     

质点法在SGARP中的新实现

可持续发展的几何自动推理平台(SGARP)支持用户发展多种多样基于规则的机器自动推理或人机交互推理方法,但缺乏处理符号计算的模块,其解题能力仍有待加强.质点法是最近发展的继面积法之后又一个能对可构造型几何命题生成可读机器证明的具有完全性的算法.基于一种在SGARP中快捷实现符号计算功能的方法,对质点法机器证明算法进行了新的实现.新添加的质点法模块使得用户能更便捷地验证更多的几何定理,从而使SGARP能更好地满足用户学习与发展几何机器推理的需求.     

通用数字电路板自动测试系统设计

实现数字电路板的自动测试与故障诊断对于保证电子设备的安全运行具有重要的意义;为满足自动测试系统通用性、标准化、可扩展性的发展需要,采用标准化、模块化的设计平台,创建了基于动态功能测试为核心的数字电路板自动测试与故障诊断系统;构建了基于VXI总线的自动测试系统硬件平台,创建了基于“背板+构件”的可扩展通用软件平台;系统结构紧凑,使用灵活,易于实现对数字电路板快速、精确的故障诊断,其诊断精度可达元器件管脚级。     

运动平台目标引导数据解算及误差分析

根据平台和目标的位置、姿态信息,利用旋转矩阵建立了运动平台目标引导模型。在此基础上进行仿真分析,通过计算平台和目标数据存在不同水平误差条件下引导数据的精度,研究了平台和目标数据对引导数据精度的影响。仿真结果表明,对方位角引导数据精度影响较大的参数为平台经度,纬度以及航向角;对俯仰角引导数据精度影响较大的参数为平台经度、纬度、俯仰角以及横滚角;对距离引导数据精度影响较大的参数为平台经度和纬度。     

人眼像差校正仪视网膜动态稳像研究

针对人眼无意识的抖动导致图像位置在眼底成像设备上无规律变化而无法有效观察指定区域的问题,提出了一种视网膜图像实时动态稳像算法.该算法依据图像匹配理论,在图像探测的同时引入图像有效区域实时"计算-移位".利用时间上相邻的视频序列图像近似对应于眼底同一位置的特点,通过"采集-运算"找到当前采集图像的中心区域.把当前图像的中心区域与第一帧采集图像的中心区域进行相关匹配,获取当前视网膜图像相对第一帧图像抖动的偏移方向和偏移量,然后把当前图像移位,循环执行此过程,并剔除无法匹配的图像,使得屏幕上的图像始终是在同一个位置的静态图像.实验证明:本文提出的算法解决了自适应眼底成像设备在对视网膜细胞观测时因为人眼自然抖动而造成的图像不稳定问题;解决了人眼在可见光波段的激光照明下受到较强刺激而无法长时观测的问题,实现了细胞和微血管同平台同算法观测;是采用拼接技术实现大视场图像的前提.     

呋喃类平台化合物催化转化成可再生化学品和燃料

正随着石油资源的相对贫乏和环境问题的加剧,寻求新的能源和途径来代替传统的化石资源越来越受到人们的关注.生物质在地球上含量丰富、分布广泛、价格较低廉且能够很好的实现碳循环,作为一种可持续和可再生资源,在取代传统的石油产品方面具有很大的潜力,能很好满足社会对燃料和化学品的需求,从而实现由不可再生的石油资源向可再生的生物能源的过渡.植物类生物质的主要成分是碳水化合物即纤维素和木质素,在一定条件下可     

Overcoming Thermodynamically Driven Retro-Diels–Alder Reaction through a Cascade One-Pot Process Exemplified for a Bio-Based Platform Chemical

In this contribution, we describe a new approach to apply thermodynamically unfavored reactions in synthetic chemistry and to integrate them in cascade processes. By means of a new developed procedure for multi-step one-pot syntheses, we succeeded in nearly completely converting a thermodynamically labile Diels–Alder adduct, which strongly tends to react back, to the target product with high conversion of >99 % and in excellent yield by coupling with a rapid subsequent hydrogenation reaction. In detail, the process is based on the use of a rotating reaction vessel to form a thin product film of the thermodynamically labile Diels–Alder product from 2-methylfuran and maleic acid anhydride (as two bio-based raw materials), which then slowly dissolves into solution and is immediately converted by hydrogenation to the target product. Such a combination of Diels–Alder reaction and hydrogenation in a sequential one-pot process without by-product formation enables the efficient production of the product, which represents a valuable bio-based platform chemical. In addition, this process concept generally opens a perspective for the integration of thermodynamically unfavorable reaction steps in multi-step one-pot cascade processes while obtaining the desired target products in high yields.     

Construction of coaxial liquid centrifugal platform for the extraction of active ingredients from natural products

In the classical natural product extraction and separation process, it is tedious and requires large amounts of reagents and time. In this study, an efficient coaxial liquid centrifugal oil-water-oil triple-liquid-phase system with a simple structure and convenient operation was successfully constructed and used to extract flavonoids from Platycladi Cacumen. The results showed that the coaxial liquid centrifugal platform constructed in this study had good stability and 6 ml was the minimum volume of the middle phase for 1000 rpm to stabilize the system. Besides, it was easy to repeat the operation: the relative standard deviations of the extraction yields of flavonoids and sugar in six parallel operations were all less than 10%. Moreover, it was only one-tenth of the time required for this method as traditional liquid-liquid extraction while reducing the use of volatile organic reagents. Finally, the new method was more selective than the traditional method for the extraction of flavonoids. Therefore, this study provides a possibility for the coaxial liquid centrifugal platform to be used in multi-liquid phase systems to achieve the simultaneous extraction of different parts of natural products by different liquid phases. It is expected to provide a reliable reference for further expansion of small-scale experimental operations to industrial production.     

Recent Progress in Fabrication of Electrospun Nanofiber Membranes for Developing Physiological In Vitro Organ/Tissue Models

Nanofiber membranes (NFMs), which have an extracellular matrix-mimicking structure and unique physical properties, have garnered great attention as biomimetic materials for developing physiologically relevant in vitro organ/tissue models. Recent progress in NFM fabrication techniques immensely contributes to the development of NFM-based cell culture platforms for constructing physiological organ/tissue models. However, despite the significance of the NFM fabrication technique, an in-depth discussion of the fabrication technique and its future aspect is insufficient. This review provides an overview of the current state-of-the-art of NFM fabrication techniques from electrospinning techniques to postprocessing techniques for the fabrication of various types of NFM-based cell culture platforms. Moreover, the advantages of the NFM-based culture platforms in the construction of organ/tissue models are discussed especially for tissue barrier models, spheroids/organoids, and biomimetic organ/tissue constructs. Finally, the review concludes with perspectives on challenges and future directions for fabrication and utilization of NFMs.     

基于ARM11的无创心血管健康评估系统设计

为了使用低成本、无创伤且易操作的方法评估人体心血管的健康状况,设计一个基于ARM11(S3C6410)的无创心血管健康评估系统,该系统由无创心血管参数检测探头、嵌入式人机交互平台和内嵌的健康评估模型三个部分组成。基于能量代谢守恒法、指端容积脉搏波检测等研制出无创检测探头,用于测量血压、血流速度和血糖等人体参数,采用蓝牙4.0设备将数据传输至嵌入式人机交互平台,数据经改进后的国人缺血性心血管病(ICVD)10年发病危险评估模型得出健康评估结果。实验结果表明该方法所得评估结果和微创真值经原始ICVD评估模型所得评估结果的Pearson相关系数为0.91(Spearman相关系数为0.891),说明该方法是可行的。