Stable germline transformation of the malaria mosquito Anopheles stephensi

Anopheline mosquito species are obligatory vectors for human malaria, an infectious disease that affects hundreds of millions of people living in tropical and subtropical countries. The lack of a suitable gene transfer technology for these mosquitoes has hampered the molecular genetic analysis of their physiology, including the molecular interactions between the vector and the malaria parasite. Here we show that a transposon, based on the Minos element and bearing exogenous DNA, can integrate efficiently and stably into the germ line of the human malaria vector Anopheles stephensi, through a transposase-mediated process.     

齿轮传动系统的计算机辅助设计

文章所阐述的齿轮传动设计系统能对各种齿轮传动进行设计计算、校核计算及其相关的数据检索、维护,并可根据设计数据自动生成工程图。介绍了齿轮传动系统数据库的建立方法,重点讨论了程序设计中经常碰到的各种表格及线图的处理问题,最后给出了一个应用实例。     

足球机器人分层决策系统的参数驱动研究

在足球机器人决策系统研究中,采用了分层的形式,考察外部信息的变化．将其分类．使之成为不同决策层的驱动源;并且把高级层决策的结果作为对象处理,使之成为低级层决策的驱动源。研究结果表明有利于各决策层对外部信息的处理．便于协调各层的传递协议。     

Major surface antigen gene of a human malaria parasite cloned and expressed in bacteria

The late blood stages of the human malaria parasite, Plasmodium falciparum, carry a major surface antigen, p190, of molecular weight (Mr) 190,000. This antigenically variable protein is actively processed, first as the parasite matures and again when it is released into the blood stream and invades a new erythrocyte to initiate a cycle of growth. It elicits a strong immune response in man; all tested adult sera from endemic areas have antibodies against this protein. Our evidence indicates that purified p190 can alter the course of parasitaemia in monkeys with falciparum malaria. We have also succeeded in cloning part of the gene for p190 and expressing it in Escherichia coli. To this end we have developed a new technique, antibody select, which greatly simplifies final identification of expressing clones.     

DSP在交流伺服系统中的应用

以TMS320LF2407芯片为控制核心,实现对PMSM(Permanent Magnetic Synchronous Motor)交流伺服电机的转速及位置控制。对交流永磁同步电机进行数学建模,并用实验验证了DSP控制的交流伺服系统具有调速范围宽、转子定位准确、响应速度快、智能水平高,以及良好动、静态性能等优点。     

A synthetic multicellular system for programmed pattern formation

Pattern formation is a hallmark of coordinated cell behaviour in both single and multicellular organisms. It typically involves cell-cell communication and intracellular signal processing. Here we show a synthetic multicellular system in which genetically engineered 'receiver' cells are programmed to form ring-like patterns of differentiation based on chemical gradients of an acyl-homoserine lactone (AHL) signal that is synthesized by 'sender' cells. In receiver cells, 'band-detect' gene networks respond to user-defined ranges of AHL concentrations. By fusing different fluorescent proteins as outputs of network variants, an initially undifferentiated 'lawn' of receivers is engineered to form a bullseye pattern around a sender colony. Other patterns, such as ellipses and clovers, are achieved by placing senders in different configurations. Experimental and theoretical analyses reveal which kinetic parameters most significantly affect ring development over time. Construction and study of such synthetic multicellular systems can improve our quantitative understanding of naturally occurring developmental processes and may foster applications in tissue engineering, biomaterial fabrication and biosensing.     

A synthetic vaccine protects humans against challenge with asexual blood stages of Plasmodium falciparum malaria

We have previously shown that a mixture of three synthetic peptides (83.1, 55.1, 35.1), corresponding to fragments of the relative molecular mass 83,000 (83K), 55K and 35K Plasmodium falciparum merozoite-specific proteins, induces protection in Aotus triviroatus monkeys experimentally infected with P. falciparum. Here we describe two polymeric synthetic hybrid proteins based on these peptides that delay or suppress the development of parasitaemia in immunized human volunteers.     

A pseudo-exon in the functional human alpha A-crystallin gene

The frequent correspondence of exons to structural or functional domains in proteins has suggested that many proteins have evolved by modular assembly. This idea is supported by examples of apparent exon duplication and by shared domains among both alternatively spliced and completely separate genes. During this process it is probable that some combinations of exons would not prove advantageous and would therefore be lost. Here we report that within the active single-copy human gene for alpha A-crystallin there is a 'pseudo-exon' in the early stages of being extinguished, perhaps the result of a failed experiment in the evolution of this specialized, lens-specific protein.     

风机水泵负载SPWM交流变频调速系统的研究

介绍了一类适用于风机、水泵负载节能运行的数字式ＳＰＷＭ交流变频调速系统。该调速装置采用ＩＧ－ＢＴ作为主功率器件,１６位单片机８０Ｃ１９６ＫＣ为控制核心,ＳＬＥ４５２０生成ＳＰＷＭ波,调速系统频率值采用数字调定,文中阐述了系统的设计原理,给出了有关的结构原理图和试验结果。     

A tissue-specific endothelial cell molecule involved in lymphocyte homing

An endothelial cell surface molecule that is selectively expressed in mucosal organs is required for lymphocyte homing to mucosal lymphoid tissues. This 'vascular addressin' appears to function as a tissue-specific marker or address signal for recognition by lymphocytes circulating in the blood.     

谐波驱动系统自适应神经网络动态面控制

针对谐波驱动系统动力学模型中存在的非线性摩擦、柔性变形和外界未知干扰力矩等因素的问题,为了提高系统的位置跟踪精度,提出了一种基于径向基函数(RBF)神经网络的谐波驱动系统自适应动态面控制.采用LuGre摩擦模型描述系统的非线性摩擦特性,用RBF神经网络在线逼近摩擦参数变化和外界未知干扰力矩对系统的影响,并通过李雅普诺夫稳定性理论证明了闭环系统的所有误差最终一致有界.仿真结果表明:与普通动态面控制相比,本控制策略对摩擦参数变化和外界未知干扰力矩具有较强的鲁棒性,提高了系统的位置跟踪精度.     

PLC在液压传动控制系统的应用

液压传动控制系统让液压缸实现自由进退动作,以便实现动力滑台的进给运动。本系统用PLC代替继电接触式控制实现液压缸的自由进退。采用可编程控制器作为其控制系统,提高液压缸的自动化程度,保证了动力滑台有连续动作的高可靠性,使系统的通用性和灵活性达到了要求。本文从可编程控制器的选择、硬件设置和程序编制等方面作了介绍。     

Genome sequence of the human malaria parasite Plasmodium falciparum

The parasite Plasmodium falciparum is responsible for hundreds of millions of cases of malaria, and kills more than one million African children annually. Here we report an analysis of the genome sequence of P. falciparum clone 3D7. The 23-megabase nuclear genome consists of 14 chromosomes, encodes about 5,300 genes, and is the most (A + T)-rich genome sequenced to date. Genes involved in antigenic variation are concentrated in the subtelomeric regions of the chromosomes. Compared to the genomes of free-living eukaryotic microbes, the genome of this intracellular parasite encodes fewer enzymes and transporters, but a large proportion of genes are devoted to immune evasion and host-parasite interactions. Many nuclear-encoded proteins are targeted to the apicoplast, an organelle involved in fatty-acid and isoprenoid metabolism. The genome sequence provides the foundation for future studies of this organism, and is being exploited in the search for new drugs and vaccines to fight malaria.     

双模糊复合控制策略及其在交流调速系统中的应用研究

双模糊复合控制相当于一类非线性PID调节器,与一般三维模糊PID控制器或模糊PI-PD复合控制器相比,具有控制规则少,动作响应快,不易丢失控制信息等优点.将双模糊复合控制应用于交流调速系统的转速环,可以提高系统的鲁棒性,加快系统的动态响应.     

Safety and immunogenicity in man of a synthetic peptide malaria vaccine against Plasmodium falciparum sporozoites

A 12 amino-acid synthetic peptide (NANP)3 comprising the immunodominant epitope of Plasmodium falciparum circumsporozoite protein was conjugated to tetanus toxoid (TT), adjuvanted with aluminium hydroxide, and administered intramuscularly in three doses at monthly intervals to 35 healthy males as a malaria vaccine. No significant adverse reactions were noted, with mild soreness at the injection site the only common symptom. Seroconversions against NANP occurred in 53% and 71% of recipients of 100 or 160 micrograms, respectively, measured by enzyme-linked immunosorbent assay (ELISA). Most ELISA-positive sera reacted with sporozoites by indirect immunofluorescence (IFA). Three vaccinees with the highest ELISA and IFA titres and four unimmunized controls were challenged with P. falciparum sporozoites introduced via the bites of infective Anopheles mosquitoes. Blood stage parasites were detected in all controls by 10 days (mean 8.5 days, range 7-10). In contrast, the two vaccinees who became infected did not manifest parasitaemia until day 11 and the third vacinee showed neither parasites nor symptoms during the 29 day observation period. This first synthetic peptide parenteral vaccine against a communicable disease tested in man is safe and stimulates biologically active antibodies. These observations encourage the development of improved vaccine formulations which, by enhancing immunogenicity, may lead to practical vaccines to assist in the control of falciparum malaria.     

VG7S变频器及其在电梯拖动系统中的应用

指出了由VG7S变频器拖动的电梯系统运转停止时序分析中的几个主要问题，探讨了使用中的抗干扰技术，并对常用控制端子的设定方法和部分调试要点作了较为详尽的说明。     

晶种在L沸石合成体系中的作用

在合成L沸石的晶化体系中,研究了晶种加入方式、L沸石晶种以及异晶晶种对合成体系的影响。结果表明,晶种加入的最佳方式为L沸石晶种分散到溶液中再与硅铝凝胶混合;在合成L沸石的体系中加入L沸石晶种,可加快晶化速度,抑制杂晶的产生。在氧化物2.65K2O∶Al2O3∶10SiO2∶(100～120)H2O(物质的量之比)的合成体系以及2.65(K2O+Na2O)∶Al2O3∶10SiO2:162H2O且n(K2O)∶n(K2O+Na2O)为0.55～0.70的合成体系中,易生成W杂晶,加入适量的L沸石晶种后,能合成纯度很高的L沸石。在合成L沸石的体系中,加入异晶晶种将降低L沸石的晶化速度,增加杂晶W沸石的相对含量。     

晶种在L沸石合成体系中的作用

在合成L沸石的晶化体系中，研究了晶种加入方式、L沸石晶种以及异晶晶种对合成体系的影响。结果表明，晶种加入的最佳方式为L沸石晶种分散到溶液中再与硅铝凝胶混合；在合成L沸石的体系中加入L沸石晶种，可加快晶化速度，抑制杂晶的产生。在氧化物2．65 K2O：Al2O3：10SiO2：(100～120)H2O(物质的量之比)的合成体系以及2．65(K2O Na2O)：Al2O3：10SiO2：162 H2O且n2(K2O):n(K2O Na2O)为0．55～0．70的合成体系中，易生成W杂晶，加入适量的L沸石晶种后，能合成纯度很高的L沸石。在合成L沸石的体系中，加入异晶晶种将降低L沸石的晶化速度，增加杂品W沸石的相对含量。