新型吸油纤维的制备及其吸油性能研究

采用悬浮聚合法,在H2O2-黄原酸酯和H2O2-FeSO4双重氧化还原体系引发下,棉纤维接枝亲油单体BMA制备成吸油纤维.通过扫描电镜观察证实了吸油纤维表面BMA层的存在,并对吸油纤维进行水面浮油吸附实验,考察了接枝率、溶液pH、温度、吸附时间等因素对吸油纤维吸油能力的影响,结果显示随着接枝率的增加吸油纤维的吸油能力呈...     

Telechelic polymers by living and controlled/living polymerization methods

Telechelic polymers, defined as macromolecules that contain two reactive end groups, are used as cross-linkers, chain extenders, and important building blocks for various macromolecular structures, including block and graft copolymers, star, hyperbranched or dendritic polymers. This review article describes the general techniques for the preparation of telechelic polymers by living and controlled/living polymerization methods; namely atom transfer radical polymerization, nitroxide mediated radical polymerization, reversible addition-fragmentation chain transfer polymerization, iniferters, iodine transfer polymerization, cobalt mediated radical polymerization, organotellurium-, organostibine-, organobismuthine-mediated living radical polymerization, living anionic polymerization, living cationic polymerization, and ring opening metathesis polymerization. The efficient click reactions for the synthesis of telechelic polymers are also presented.     

Microwave-assisted polymer synthesis (MAPS) as a tool in biomaterials science: How new and how powerful

Lack of reproducibility, difficult and expensive scale-up and standarization of synthetic processes are the main hurdles towards the industrial production of raw synthetic and semi-synthetic polymers for (bio)pharmaceutical applications. Time- and energy-consuming synthetic pathways that usually involve the use of volatile, flammable or toxic organic solvents are apparently cost-viable and environment-friendly for the synthesis at a laboratory scale. However, they are often not viable in industrial settings especially due to the impact they have on the product cost and the deleterious effect on the environment. This has presented hurdles to the incorporation of many new biomaterials displaying novel structural features into clinics. Nevertheless, owing to unique advantages such as shorter reaction times, higher yields, limited generation of by-products and relatively easy scale-up without detrimental effects, microwave-assisted organic synthesis has become an appealing synthetic tool. Regardless of these features, the use of microwave radiation in biomaterials science has been comparatively scarce. A growing interest in the basic aspects of the synthesis of either ceramic and polymeric biomaterials has been apparent during the last decade. This article reviews the most recent and prominent applications of MW as a versatile tool to synthesize and process organic and inorganic polymeric biomaterials, and discusses the unmet goals and the perspectives for a technology that probably has the potential to make biomaterials more accessible pharmaceutical excipients and the products that involve them more affordable to patients.     

一种基于率失真准则的快速块匹配算法

运动估计中的块匹配算法已在各个视频编码标准中广泛采用。随着率失真准则的采用,尤其是在一些低比特率的应用中,传统的快速块匹配算法并不能很好的适合。该文提出了一种基于连续排除算法的修正算法。在率失真准则下,搜索区域中的须进行匹配计算的位置由一不等式限定。该算法的性能和全搜索算法一致,但显著减少了计算量。     

分流量区间BMA方法在小流域暴雨山洪模拟中的应用——以官山小流域为例

小流域山洪灾害具有成灾时间短、突发性强、危害性大、频次多等特点,严重威胁着区域内社会经济发展和人民群众生命财产安全。受当前山区雨洪资料少、产汇流机理不够完善所限,小流域的暴雨洪水模拟存在着可靠性差、精度低的问题。以我国中部秦巴山区山洪灾害典型流域官山小流域为研究对象,搜集了近期代表性较好的10场洪水,以TOPMODEL、TUWMODEL和新安江模型结果为基础,基于分流量区间BMA方法计算模型权重,提出适用于小流域的水文集合预报模型。结果显示,相比单一水文模型,分流量区间BMA方法模拟的洪峰流量、洪量和峰现时间指标的合格率可分别提高4.5%、39.7%和48.9%,为官山小流域洪水模拟提供了一种有效的模拟手段。研究成果对提高山区小流域洪水预报精度具有一定的理论意义和实践价值。     

Complex polymer architectures via RAFT polymerization: From fundamental process to extending the scope using click chemistry and nature's building blocks

Reversible addition fragmentation chain transfer (RAFT) polymerization has made a huge impact in macromolecular design. The first block copolymers were described early on, followed by star polymers and then graft polymers. In the last five years, the types of architectures available have become more and more complex. Star and graft polymers now have block structures within their branches, or a range of different branches can be found growing from one core or backbone. Even the synthesis of hyperbranched polymers can be positively influenced by RAFT polymerization, allowing end group control or control over the branching density. The creative combination of RAFT polymerization with other polymerization techniques, such as ATRP or ring-opening polymerization, has extended the array of available architectures. In addition, dendrimers were incorporated either as star core or endfunctionalities. A range of synthetic chemistry pathways have been utilized and combined with polymer chemistry, pathways such as ‘click chemistry’. These combinations have allowed the creation of novel structures. RAFT processes have been combined with natural polymers and other naturally occurring building blocks, including carbohydrates, polysaccharides, cyclodextrins, proteins and peptides. The result from the intertwining of natural and synthetic materials has resulted in the formation of hybrid biopolymers. Following these developments over the last few years, it is remarkable to see that RAFT polymerization has grown from a lab curiosity to a polymerization tool that is now been used with confidence in material design. Most of the described synthetic procedures in the literature in recent years, which incorporate RAFT polymerization, have been undertaken in order to design advanced materials.     

视频编码中基于时空信息运动估计的研究

提出了一种基于视频图像的时间和空间相关性信息的运动矢量预测方法，由于相领两帧图像中的内容应具有相关性，图像中物体的运动轨迹也具有相似性，因此可以利用前一帧图像中宏块的运动矢量确定运动轨迹，进而估计当前宏块的运动矢量，但是这种运动估计是受限的，因为估计运动矢量时的宏块顺序是逐行的按先后顺充进行，在当前帧中，当前宏块预测时只能利用具有因果关系的相邻宏块，但其与相邻宏块并非都具有因果关系，因此给出了预测矢量的资格检验方法，用以判断和剔除伪预测矢量，在搜索过程中采用菱形搜索（Pyramid)，相邻的两次搜索过程，要去除两个重叠区域，上述算法减少计算量，对Suzie序列测试结果，平均搜索次数是14－17次，并且解码图像的信噪比PSNR与FS搜索相比降级不多。     

基于BMA安全模型的客户信息保护

随着信息化建设步伐的不断加快,移动通信是私人信息传递的重要渠道,但是客户信息管理的安全性方面还存在很多问题,保护客户信息安全与隐私尤为重要。针对电信企业面临的挑战,提出了电信企业客户信息安全保护模型,重点从保护策略、技术保障两方面提出保护客户信息安全的措施,对于电信企业保障客户信息安全有重要参考价值。     

图像序列运动估计中经典块匹配算法研究

对图像序列运动估计中的穷尽搜索法、三步法、新三步法和菱形法等块匹配算法的基本思想、算法描述、搜索模板以及算法性能进行分析和研究,并在实验仿真中,采用平均每块搜索点数和平均峰值信噪比PSNR为衡量指标,测试了在三种典型的视频序列运动估计中每种算法的搜索速度和效果,得出菱形法综合性能更为优越的结论。     

一种改进的快速全局运动估计算法

结合两步法与传统梯度下降算法,提出一种改进的快速全局运动估计算法。采用稀疏抽样的MSEA快速块匹配算法估计局部运动矢量,使用迭代最小二乘法粗估计全局运动参数并排除外点(前景宏块),在排除外点的采样宏块集上选取特征像素,以上述两步法的全局运动估计参数为初始值,利用LM梯度下降算法对全局运动参数进行优化。实验结果表明,改进算法的估计速度达到11.42 ms/f,比FFRGMET算法快1.3倍,具有更高的全局运动估计精度。