PA6/PBT共混物的增容改性研究

采用固体环氧树脂(EP)反应增容聚酰胺6/聚对苯二甲酸丁二醇酯(PA6/PBT)共混物。结果表明:EP的加入降低了共混物的界面张力,使分散相粒径明显细化;当PA6/PBT=80/20,EP含量为1～1.5份时,共混物的改性效果较好;当PA6用量少于30份或超过70份时,EP的加入可明显提高共混物的冲击性能和拉伸性能;随着EP的加入,共混物的流动性降低。     

改性凹凸棒石粘土的制备及其对印染废水的处理效果

以凹凸棒石粘土为原料,采用三氯化铝（AlCl3）对凹凸棒石粘土进行改性,探讨了改性凹凸棒石粘土投量、pH值、吸附时间对处理效果的影响。结果表明：改性凹凸棒石粘土投加浓度为50g／L,吸附时间为40min,pH值=3时,印染废水的脱色率可达98％;该方法具有处理效果好,操作简单等优点;热再生是凹凸棒石粘土最好的再生方法。     

从上海世博看城市建设的创新及其相关启示

本文综合介绍了上海世博会在规划设计理念上、建筑创作理念上和运营管理方式上的创新等方面的相关情况及对我国城市建设的相关启示,为读者提供可借鉴的资料,以期促进祖国现代化的进程。     

A Priority Based Opportunistic Routing Mechanism for Real-Time Voice Service in Mobile Ad hoc Networks

Traditional routing protocols send traffic along pre-determined paths and have been shown ineffective in coping with unreliable and unpredictable wireless medium which is caused by the multi-path fading. The most difference between the opportunistic routing and the traditional routing mechanism is that the opportunistic routing mechanism can use several lossy broadcast links to support reliable transmission. In this paper, an opportunistic routing mechanism for real-time voice service is proposed. This mechanism is based on the dynamic source routing (DSR) protocol with some modifications, the routing messages of DSR are used to construct the forwarder list, which guides the data packets forwarding process. The forwarder nodes have priorities to restrict the number of duplicated packets. Simultaneous flows can be supported well by our mechanism. Simulations show that our mechanism can effectively decrease the data packets transmission times and the amount of the control messages and reduce the end-to-end delay for real-time voice service, the quality of service can be supported well over the unstable wireless channel.     

Optimized reduction of spur tones in fractional frequency synthesizers

In this article the contribution of the digital \Upsigma\Updelta\Upsigma\Updelta modulator in fractional frequency synthesizers is explored. Due to the circuit’s non linear behavior, the spur tones generated by the digital \Upsigma\Updelta\Upsigma\Updelta modulation degrade the synthesizer’s phase noise even in regions where the charge pump noise is dominant. A new method to dither digital MASH \Upsigma\Updelta\Upsigma\Updelta modulators for fractional frequency synthesizers is proposed. The method barely increases the circuit complexity and has the same performance as more cumbersome architectures. Also, a new design consideration to linearize the voltage control oscillator is proposed. Experimental results are obtained in an on-chip fractional synthesizer manufactured in CMOS technology.     

罗非昔布对胃癌细胞上清液中培养的树突状细胞分化成熟和功能的影响

目的：从免疫学角度分析罗非昔布（Rofecoxib）抗癌作用的机制。方法：将人外周血分离的单核细胞加入含重组人粒细胞巨噬细胞集落刺激因子和重组人白细胞介素的培养液中,随机分为空白组（PBS培养液）,干预组（胃癌细胞上清液＋罗非昔布,150mg/L）,对照组（胃癌细胞上清液）使其分化为树突状细胞（denstritic cell,DC）。混合培养48h后,动态观察DC成熟过程中的形态学变化,流式细胞术检测DC成熟表型（CD40、CD80）,混合T淋巴细胞增殖反应检测DC功能。结果：与对照组比较,空白组、干预组DC的CD40、CD80表达明显在增加（P〈0.05）,T细胞增殖作用明显增强（P〈0.05）。结论：罗非昔布可通过促进DC成熟,并增加DC的免疫活性而发挥抗癌作用。     

The Co-Au interface in bimetallic nanoparticles: a high resolution STEM study

We report the formation of Au/Co nanoparticles and their characterization by aberration (Cs) corrected scanning transmission electron microscopy (STEM). The nanoparticles were synthesized by inert gas condensation, forming initially core-shell and bimetallic crystals. However, after thermal treatment at normal atmospheric conditions, the Co nanoparticles changed their morphology into a fine layer forming a perfect interface with the gold. The ordering of the zone rich in Co presents a fcc arrangement matching the gold lattice. The atomic analysis on the interface and the comparison of the STEM images with numerical simulations corroborated the atomic substitution of gold by cobalt.     

Gene Therapy in HIV‐Infected Cells to Decrease Viral Impact by Using an Alternative Delivery Method

The ability of dendrimer 2G‐[Si{O(CH₂)₂N(Me)₂⁺(CH₂)₂NMe₃⁺(I^?)₂}]₈ (NN16) to transfect a wide range of cell types, as well as the possible biomedical application in direct or indirect inhibition of HIV replication, was investigated. Cells implicated in HIV infection such as primary peripheral blood mononuclear cells (PBMC) and immortalized suspension cells (lymphocytes), primary macrophages and dendritic cells, and immortalized adherent cells (astrocytes and trophoblasts) were analyzed. Dendrimer toxicity was evaluated by mitochondrial activity, cell membrane rupture, release of lactate dehydrogenase, erythrocyte hemolysis, and the effect on global gene expression profiles using whole‐genome human microarrays. Cellular uptake of genetic material was determined using flow cytometry and confocal microscopy. Transfection efficiency and gene knockdown was investigated using dendrimer‐delivered antisense oligonucleotides and small interfering RNA (siRNA). Very little cytotoxicity was detected in a variety of cells relevant to HIV infection and erythrocytes after NN16 dendrimer treatment. Imaging of cellular uptake showed high transfection efficiency of genetic material in all cells tested. Interestingly, NN16 further enhanced the reduction of HIV protein 24 antigen release by antisense oligonucleotides due to improved transfection efficiency. Finally, the dendrimer complexed with siRNA exhibited therapeutic potential by specifically inhibiting cyclooxygenase‐2 gene expression in HIV‐infected nervous system cells. NN16 dendrimers demonstrated the ability to transfect genetic material into a vast array of cells relevant to HIV pathology, combining high efficacy with low toxicity. These results suggest that NN16 dendrimers have the potential to be used as a versatile non‐viral vector for gene therapy against HIV infection.     

Synthesis of Fatty Acid Amides of Catechol Metabolites that Exhibit Antiobesity Properties

A series of fatty acid amides of 3,4‐methylenedioxymethamphetamine (MDMA) catechol metabolites were synthesized in order to evaluate their biological activities. Upon administration, all synthesized compounds resulted in negative modulation of food intake in rats. The most active compounds have affinity for the CB₁ receptor and/or PPAR‐α; part of their biological activity may be caused by these double interactions.