Syntheses,Structures and Sorption Properties of Three Isoreticular Trinuclear Indium‐Based Amide‐Functionalized Metal–Organic Frameworks

Amide‐functionalized metal–organic frameworks (AFMOFs) as a subclass of MOF materials have received great interest recently because of their intriguing structures and diverse potential applications. In this work, solvothermal reactions between indium nitrate and two mixed‐linkers afforded two new isoreticular 8‐connected trinuclear indium‐based AFMOFs of [(In₃O)(OH)(L2)₂(IN)₂]?(solv)_x ( 2‐In ) and [(In₃O)(OH)(L2)₂(AIN)₂]?(solv)_x ( NH₂‐2‐In ) (H₂L2=4,4′‐(carbonylimino)dibenzoic acid and HIN=isonicotinic acid or HAIN=3‐aminoisonicotinic acid), respectively. Moreover, by means of reticular chemistry, an extended network of [(In₃O)(OH)(L3)₂(PB)₂]?(solv)_x (3‐In) (H₂L3=4,4′‐(terephthaloylbis(azanediyl))dibenzoic acid, HPB=4‐(4‐pyridyl)benzoic acid) was also successfully realized after prolongation of the former dicarboxylate linker and HIN, resulting in a truly 8‐connected isoreticular AFMOF platform. These frameworks were structurally determined by single‐crystal X‐ray diffraction (SCXRD). Sorption studies further demonstrate that 2‐In and NH₂‐2‐In exhibit not only high surface areas and pore volumes but also relatively high carbon capture capabilities (the CO₂ uptakes reach 60.0 and 75.5 cm³ g^?1 at 298 K and 760 torr, respectively) due to the presences of amide and/or amine functional groups. The selectivity of CO₂/N₂ and CO₂/CH₄ calculated by IAST are 10.18 and 12.43, 4.20 and 4.23 for 2‐In and NH₂‐2‐In , respectively, which were additionally evaluated by mixed‐gases dynamic breakthrough experiments. In addition, high‐pressure gas sorption measurements show that both materials could take up moderate amounts of natural gas.     

A Light-Activated Acyl Carrier Protein “Trap” for Intermediate Capture in Type II Iterative Polyketide Biocatalysis

A discrete acyl carrier protein (ACP) bearing a photolabile nonhydrolysable carba(dethia) malonyl pantetheine cofactor was chemoenzymatically prepared and utilised for the trapping of biosynthetic polyketide intermediates following light activation. From the in vitro assembly of the polyketides SEK4 and SEK4b, by the type II actinorhodin “minimal” polyketide synthase (PKS), a range of putative ACP-bound diketides, tetraketides, pentaketides and hexaketides were identified and characterised by FT-ICR-MS, providing direct insights on active site accessibility and substrate processing for this enzyme class.     

一种基于残差系数的快速编码算法

当前视频编码标准有着较高的编码效率,然而也较多地提高了编码复杂度,因此提高编码速度具有很重要的意义。根据残差系数的分布特征,该文提出了一种基于残差的快速编码算法。该算法首先根据Inter1616或者Inter88编码得到的残差系数进行假设检验,根据假设检验的结果来预测可能的编码模式集合;然后根据DCT系数的分布特征分别计算出全零块,11子块,22子块和33子块的判决条件,从而避免44子块中全部或者部分系数的DCT,Q,IQ,IDCT运算。实验证明,该文算法的编码速度要显著快于其它算法,同时编码效率的损失也很小。     

A Comprehensive Study of CO2 Absorption and Desorption by Choline-Chloride/Levulinic-Acid-Based Deep Eutectic Solvents

Amine absorption (or amine scrubbing) is currently the most established method for CO₂ capture; however, it has environmental shortcomings and is energy-intensive. Deep eutectic solvents (DESs) are an interesting alternative to conventional amines. Due to their biodegradability, lower toxicity and lower prices, DESs are considered to be “more benign” absorbents for CO₂ capture than ionic liquids. In this work, the CO₂ absorption capacity of choline-chloride/levulinic-acid-based (ChCl:LvAc) DESs was measured at different temperatures, pressures and stirring speeds using a vapour–liquid equilibrium rig. DES regeneration was performed using a heat treatment method. The DES compositions studied had ChCl:LvAc molar ratios of 1:2 and 1:3 and water contents of 0, 2.5 and 5 mol%. The experimental results showed that the CO₂ absorption capacity of the ChCl:LvAc DESs is strongly affected by the operating pressure and stirring speed, moderately affected by the temperature and minimally affected by the hydrogen bond acceptor (HBA):hydrogen bond donator (HBD) molar ratio as well as water content. Thermodynamic properties for CO₂ absorption were calculated from the experimental data. The regeneration of the DESs was performed at different temperatures, with the optimal regeneration temperature estimated to be 80 °C. The DESs exhibited good recyclability and moderate CO₂/N₂ selectivity.     

Holographic microrheology of polysaccharides from <Emphasis Type="Italic">Streptococcus mutans</Emphasis> biofilms

We use three-dimensional holographic particle tracking to perform microrheological measurements of model gelled media, including the polysaccharide pellicle of dental biofilms created by the common cariogenic oral pathogen Streptococcus mutans. Nanometer-resolution video-rate holographic tracking of embedded colloidal spheres provides accurate measurements of the gels’ complex viscoelastic moduli, including insights into these properties’ heterogeneity. When applied to polysaccharides of S. mutans biofilms, these techniques promise quantitative microscopic assays for candidate therapeutic agents against cariogenic dental biofilms.     

一种用于空间目标捕获的宽视场可见光光学系统的设计

设计了一种对空间目标进行捕获并跟踪的可见光相机的光学系统.该成像系统采用了7组共8片的复杂化双高斯结构,焦距40.65 mm,相对孔径为1/1.7,全视场角28°,光谱范围为可见光谱段.该系统可完成对空间目标的捕获和跟踪测量任务,并提供目标图像信息.针对大视场大相对孔径的空间目标探测要求提出了光学系统参量的确定方法,结合设计实例给出一种双高斯向反远距演变的设计思路.     

基于统计特性与边缘特性融合的阴影检测方法

针对视频监视系统中的阴影检测问题,提出了一种基于灰度比值统计与边缘特征分析相融合的阴影检测方法.根据阴影的面积和灰度特征,采用灰度统计和正态分布曲线拟合的方法估计出阴影灰度的分布区域,实现对阴影的初分割.利用熵判据对初分割的结果进行判断,对于过分割的情况,依据目标与阴影间的位置关系,利用阴影的边缘特性进行目标重构.不同光照环境下的视频监控图像测试结果表明,该方法可以用于灰度图像和彩色图像,能够有效检测出阴影区域并保持目标的完整性.     

基于感兴趣区域的幅型比变换新方法

基于人类视觉系统对运动目标比较敏感的特性,提出了一种新的幅型比变换方法.综合时空信息提取视频序列中的运动目标,利用图像修复技术对被提取运动目标后的视频图像进行背景修补.采用插值算法以不同的方式分别缩放运动目标和修复后的背景,并将变换后的运动目标与背景相叠加合成相应幅型比的视频图像.实验结果表明：此方法避免了已有幅型比变换方法的缺陷,保证了变换后运动目标的无失真性,与人类的视觉感知有较好的一致性.     

K-forbidden allowed $ \beta$ transitions in heavy nuclei

The role of the band quantum number K in influencing the character of allowed transitions in heavy deformed nuclei is examined. The conditions for the occurrence of K -forbidden decays in this region are explored. Specific cases of “allowed” decays proceeding via K = 2 to K = 6 channels are presented to illustrate the phenomenon. The listed K = 2 transitions, which by themselves contribute over 10% of all the presently known allowed transitions for A 228 nuclei, are seen to have an average , which is clearly outside the normal range for allowed transitions. It is concluded that, wherever the -connected states can be confidently labelled using the quantum numbers, the K -forbiddenness is in general as significant as that involving the other two (spin and parity) quantum numbers.     

Performance of Video Telephony Services in UMTS using Live Measurements and Network Emulation

While speech services in mobile communication systems are investigated quite well, video telephony services are relatively novel in this sector. Because of the market penetration of camera equipped mobile phones the video telephony service is expected to become a widely used service. In this article an introduction of the protocols used for video telephony in UMTS is given. Concepts for the performance evaluation in terms of video (PEVQ) and audio quality (PESQ) are presented and utilized. Evaluations are performed by both live measurements and network emulation. The results show that there is quite potential for improvements related to video telephony in UMTS in terms of video quality and channel setup time. Finally, an improved radio bearer configuration is provided which aims at a better integration of video telephony services into the UMTS architecture.