DNA/Tannic Acid Hybrid Gel Exhibiting Biodegradability,Extensibility, Tissue Adhesiveness,and Hemostatic Ability

DNA has emerged as a novel material in many areas of materials science due to its programmability. Especially, DNA hydrogels have been studied to incorporate new functions into gels. To date, only a few methods have been developed for fabricating DNA hydrogels, such as the use of complementary sequences or covalent bond. Herein, it is demonstrated that one of the most well‐known plant‐derived polyphenols, tannic acid (TA), can form a DNA hydrogel which is named TNA hydrogel ( T A + D NA ). TA plays a role as a “molecular glue” by a new mode of action reversibly connecting between phosphodiester bonds, which is different from the crosslinking utilizing complementary sequences. TA intrinsically degrades due to ester bonds connecting between pyrogallol groups, causing a degradable DNA hydrogel. Furthermore, TNA gel is multifunctional in that the gel is extensible upon pulling and adhesive to tissues because of the rich polyphenol groups in TA (ten phenols per TA). Unexpectedly, TNA gel exhibits superior in vivo hemostatic ability that can be useful for biomedical applications. This new DNA hydrogel preparation method represents a new technique for fabricating a large amount of DNA‐based hemostatic hydrogel without chemically modifying DNA or requiring the crosslinking by complementary sequences.     

办公空间臭氧污染状况数值模拟

室内臭氧污染会引发多种疾病,日益受到人们的关注。以CFD数值模拟为手段,运用RNG k-ε模型对某办公室内的臭氧流动扩散、衰减等现象进行了模拟,得到了不同工况下的臭氧浓度场。结果表明:臭氧在室内表面处的衰减会显著降低室内臭氧浓度;办公室内复印机等臭氧源的散发会导致室内臭氧浓度的增加;新风臭氧含量决定了当新风量增加时室内臭氧浓度的变化趋势。结合模拟结果,提出了室内臭氧污染防治的几点措施。     

320 Gbit/s光时分复用系统研究

针对高速率OTDM(光时分复用)系统中的一些关键技术问题,如时钟提取、时分解复用和色散补偿等,提出了8×40Gbit/s的OTDM系统技术方案。结果表明,通过选择合适的时钟提取方式和基于对称性色散位移光纤的色散补偿技术,能够实现在一个时隙内对每个信道的40 Gbit/s归零码信号的解复用,且解复用后的信号质量较好。该系统实现了320Gbit/s OTDM通信。     

工期对工程造价的影响

"质量好、工期短、造价低"是对建设工程提出的三大要求。本文阐述工期的定义及其意义,工期与造价的对立统一关系及确定合理工期,以期提高企业的经济效益。     

当代城市空间的符号价值

随着中国发达地区城市由生产社会向消费社会的转型,空间呈现商品化的发展态势,空间符号价值的重要性也日益突显出来。一方面,城市空间所象征的个性和品位、身份和地位、生活方式等符号意义逐渐成为大众空间消费过程中所关注的重点;另一方面,空间符号的消费强化了空间的社会属性,并为城市带来新的发展契机。     

浅谈港口工程项目实施阶段的造价控制与管理

近几年,我国建设行业飞速发展,港口建设迅速增加,如想在激烈的竞争中生存与发展,需对港口企业在开发建设过程中的造价进行控制与管理。本文阐述了建设单位在港口工程项目实施阶段的造价控制措施与管理方法。     

地铁运营线路既有普通扣件地段更换谐振式浮轨扣件施工工艺

本文以地铁施工中的轨道工程施工为背景,介绍如何在地铁运营线路既有普通扣件地段更换谐振式浮轨扣件。     

Design and dimension optimization of cutter disassembly mechanism for shield tunneling machine

Journal of Mechanical Science and Technology - This study focuses on configuration and dimension optimization of cutter disassembly mechanism. Firstly, a cutter disassembly mechanism configuration...     

基于共轴球面并联3RRR机构的手腕康复装置研制

针对中风患者腕部运动功能障碍及康复训练问题,提出了一种基于共轴球面并联3RRR机构的手腕康复装置.该装置由3个电机驱动,末端执行机构能够实现球面运动,以模拟手腕3自由度复合运动,实现手腕康复训练.为了达到紧凑性设计的目的,采用了三轴共轴球面并联机构和同步带传动的设计方案.在此基础上,建立手腕康复装置运动学数学模型,获得了电机输入角度与末端执行机构输出位姿之间的关系;并确定康复装置的工作空间:绕X轴旋转最大角度为32°,绕Y轴旋转最大角度为37°,绕Z轴全周旋转.最后,加工出实验样机进行实验验证.结果表明,该装置运转平稳,工作空间内不存在卡死现象.     

Exponential wavelet iterative shrinkage thresholding algorithm with random shift for compressed sensing magnetic resonance imaging

We propose the use of exponent of wavelet transform (EWT) coefficients as a sparse representation which is combined with the iterative shrinkage/threshold algorithm (ISTA) for the reconstruction of compressed sensing magnetic resonance imaging. In addition, random shifting (RS) is employed to guarantee the translation invariance property of discrete wavelet transform. The proposed method is termed the exponential wavelet iterative shrinkage/threshold algorithm with random shifting (EWISTARS), which takes advantages of the sparse representation of EWT, the simplicity of ISTA, and the translation invariance of RS. Simulation results on brain, vertebrae, and knee MR images demonstrate that EWISTARS is superior to existing algorithms with regard to reconstruction quality and computation time. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.