Improving resins for solid phase synthesis: incorporation of 1-[2-(2-methoxyethoxy)ethoxy]-4-vinyl-benzene

The preparation, characterisation and application of a series of non-grafted polystyrene (PS) resins containing a styrenic methoxypoly(ethylene glycol) (MPEG) derivative is presented. These novel PS-MPEG resins were designed to balance swelling and solvation with improved handling. The monomer, 1-[2-(2-methoxyethoxy)ethoxy]-4-vinyl-benzene, contained an inert phenyl ether linkage designed to provide broad chemical compatibility and stability, yet imparting all the favourable properties of the PEG group into the new resin, whilst maintaining a high loading capacity. The synthetic performance of the new resins compared very favourably to those of TentaGel™, ArgoGel™ and aminomethyl PS.     

Acoustic Analysis of Pathological Voices Compressedwith MPEG System

The MPEG-1 Layer 3 compression schema of audio signal, commonly known as mp3, has caused a great impact in recent years as it has reached high compression rates while conserving a high sound quality. Music and speech samples compressed at high bitrates are perceptually indistinguishable from the original samples, but very little was known about how compression acoustically affects the voice signal. A previous work with normal voices showed a high fidelity at high-bitrate compressions both in voice parameters and the amplitude-frequency spectrum. In the present work, dysphonic voices were tested through two studies. In the first study, spectrograms, long-term average spectra (LTAS), and fast Fourier transform (FFT) spectra of compressed and original samples of running speech were compared. In the second study, intensities, formant frequencies, formant bandwidths, and a multidimensional set of voice parameters were tested in a set of sustained phonations. Results showed that compression at high bitrates (96 and 128 kbps) preserved the relevant acoustic properties of the pathological voices. With compressions at lower bitrates, fidelity decreases, introducing some important alterations. Results from both works, Gonzalez and Cervera and this paper, open up the possibility of using MPEG-compression at high bitrates to store or transmit high-quality speech recordings, without altering their acoustic properties.     

MPEG音频编码的高效算法研究及单片DSP实现

ＩＳＯ标准推荐ＭＰＥＧ－１音频编码算法要实现起来运算复杂,为便于单片ＤＳＰ实现,算法可以优化。本文简要分析了该算法的各个模块并估计了它们的运算复杂性,然后对子带滤波和心理声学模型作了进一步的探讨,提出了基于逆余弦变换（ＩＤＣＴ）的子带滤波的高效实现算法和不用ＦＦＴ或只用部分ＦＦＴ的快速心理声学掩蔽计算模型。最后用单片ＴＭＳ３２０Ｃ３１＠４０ＭＨｚ实现了ＭＰＥＧ－１层２编码算法。     

基于DC直流系数的盲视频水印算法

为了增强抗攻击的能力和保证算法的不可见性，基于DC直流系数的稳定性，把选择的视频帧分成8×8块，每块经过2次DCT变换，提取与每块像素RGB平均值成正比的DC直流系数，将这些DC系数组织成一维序列，并划分为更小的子序列，然后对每个子序列进行一维DCT变换，通过比较相邻2个子序列中最后一个高频系数值的大小来嵌入水印．实验结果表明：该算法有较高的视觉质量，同时对于MPEG压缩，帧置换，加噪等处理有良好的鲁棒性，在水印的提取过程中不需要任何附加信息．     

用于纳米载药系统的两亲性聚乙二醇-药物分子偶联体的合成及胶束化性质

设计和合成了两亲性树枝状药物载体化合物6-Arm MPEG-Drug Conjugate,其中所使用的模型药物分子为苯甲酸.用1H NMR和13C NMR测试对结构进行了表征. 1H NMR谱图表明载体化合物在有机溶剂和水中表现不同的聚集行为,在水中自组装形成纳米微粒.利用荧光探针技术、动态激光光散射和扫描电镜研究其在水中的胶束化行为.结果显示,该药物载体化合物具有很低的临界胶束浓度,2.5×10-2 mg/mL (5.3×10-6 mol/L);在水溶液中浓度为1.0 mg/mL时的流体力学直径为67.4 nm,多分散指数为0.106;通过扫描电镜观察发现,初始浓度不同形成的聚集体形态也不同,得到了管状和方形结构胶束,而且随着不同水量的加入,聚集态从管状转变为囊泡状结构.     

Design of “smart” segmented polymers by incorporating random copolymers as building blocks

This article is dealing with the design of novel segmented polymers comprising homopolymer and random copolymer building blocks designated as block-random. This type of polymeric materials can be prepared through macromolecular engineering by using controlled polymerization methods. By replacing a homopolymer block with a random one, in block copolymer topologies, further tuning of the copolymer properties can be achieved. The present article highlights the recent developments on block-random segmented macromolecules, bearing building blocks of tunable properties (e.g. thermo-sensitivity (LCST), hydrophobicity) and exhibiting responsive behavior in aqueous environments. Furthermore, preliminary novel results regarding pH-sensitive segmented macromolecules of various topologies, bearing random polyampholyte blocks among others, are also demonstrated and discussed.     

End-to-end QoS issues of MPEG-4 FGS video streaming traffic delivery in an IP/DVB/UMTS network

The paper addresses the end-to-end QoS problem of MPEG-4 FGS video streaming traffic delivery over a heterogeneous IP/DVB/UMTS network. It proposes and validates an architecture that explores the joint use of packet prioritization and scalable video coding together with the appropriate mapping of UMTS traffic classes to the DiffServ traffic classes. A set of experimental scenarios, involving eight different video sequences, demonstrates the quality gains of both scalable video coding and prioritized packetization.     

MPEG-2先进音频编码(AAC)的研究和软件仿真

ＭＰＥＧ－２ＡＡＣ是ＩＳＯ／ＩＥＣ ＭＰＥＧ组织继 ＭＰＥＧ－１、ＭＰＥＧ－２音频编解码标准后,制定 的最新国际标准（ＩＳＯ／ＩＥＣ １３８１８－７）,在６４ｋｂｐｓ／每声道低码率时能提供全透明音质。本文对其编 解码算法进行了简要介绍。论文作者对ＭＰＥＧ－２ＡＡＣ进行了软件仿真,文中介绍了仿真结果,仿 真时对ＡＡＣ标准所附编码范例中的一些不妥之处,作了改进,文中列举了６方面的修正。