超级VCD与DVD的市场之争

《超级ＶＣＤ技术规范》终于在去年由信息产业部颁布，就此超级ＶＣＤ开始正式上市。超级ＶＣＤ与ＤＶＤ之争的大幕也就此拉开了。ＳＶＣＤ结合了ＤＶＤ与ＶＣＤ的优点，具有以下的性能特点和使用功能：１高品质的影音播放效果。ＳＶＣＤ的图像分辨格式为２／３Ｄ１，像...     

PVDC的应用

ＰＶＤＣ,学名为“聚偏二氯乙烯”,其单体ＶＤＣ（偏氯乙烯）于１８３０年由法国化学家Ｒｅｇｎａｉｌｔ发现并第一次进行了记述,由于ＶＤＣ的融化温度与分解温度很接近,所以当时ＰＶＤＣ没有得到实质性的应用。二十世纪３０年代,人们发现如果使ＶＤＣ与ＶＣ或ＭＡ一起进行共聚,不仅能保持ＰＶＤＣ的许多优良特生,又能降低熔融温度,易于加工成型,对此陶氏化学公司做出了大量的研究,并为其工业化生产的ＰＶＤＣ聚合物树脂注册为“Ｓａｒａｎ”商标,这是第一个商品化的ＰＶＤＣ产品,我们在中国称其为“莎伦”。 ＰＶＤＣ生产的薄…     

应用带HSV－TK基因的重组腺病毒的肺癌基因治疗的研究

带有单纯疱疹病毒脱氧胸苷激酶基因（ＨＳＶ－ｔｋ）的腺病毒结合ｇａｎｃｉｃｌｏｖｉｒ（ＧＣＶ）对分裂细胞有很强的杀伤作用。本文报道在感染复数（Ｍ．Ｏ．Ｉ,ＭｕｌｔｉＰｌｉｃｉｔｙｏｆＩｎｆｅｃｔｉｏｎ）达到１０００时对人体肺腺癌细胞Ａ５４９的杀伤几乎达到回１００％。四种人体肺癌细胞株（Ａ５４９,ＬＡＸ,ＳＰＣ,ＳＫＹ）对带ＨＳＶ－ｔｋ的腺病毒（ＡＤＶ／ＲＳＶ－ｔＫ）的杀伤作用表现不同的敏感性。另外,Ａｃｙｃｌｏｖｉｒ（ＡＣＶ）和ＧＣＶ对感染了重组腺病毒ＡＤＶ／ＲＳＶ－ｔＫ的细胞都有一定杀伤作用,但杀伤效果有很大差别;就Ａ５４９而言,ＧＣＶ的杀伤作用比ＡＣＶ高７—８倍。此外ＡＤＶ／ＲＳＶ－ｔｋ结合ＧＣＶ杀伤肿瘤细胞时有“旁观者效应”,即感染了ＡＤＶ／ＲＳＶ－ｔｋ的细胞与未感染细胞混合后,后者也明显地遭到杀伤。     

具有动态偏压的甲类放大器

具有动态偏压的甲类放大器小电一、电路性能简介由电路图可知，这部功放的输入级是一对场效应管，输入阻抗高、动态范围大、噪声低。Ｖ３、Ｖ４组成第Ｍ差分放大级，ＶＳ提供１．８ｍＡ的电流给Ｖ１、Ｖ２；Ｖ６提供９．５ｍＡ的恒定电流给Ｖ３、Ｖ４。由于ＬＥＤ的导通（...     

世界上最小的DVD播放器

日本松下公司新近推出最小的ＤＶＤ播放器ＤＶＤ－Ｌ５０掌上剧院（ＤＶＤ－Ｌ５０ＰａｌｍＴｈｅａｔｅｒ），可以作为便携式ＤＶＤ播放器在旅行时使用，也可以作为家庭影院系统的一部分与其它设备集成在一起使用。ＤＶＤ－Ｌ５０是松下公司去年推出的ＤＶＤ－Ｌ１０的升...     

开始要设计一匹马 超级CD格式的再思考

一年多前的国际音响大展上超级音频ＣＤ ＳＡＣＤ和ＤＶＤ－Ａｕｄｉｏ就放声高歌,基本标准１．０版本也已敲定,按说应该在音响发烧友的期望中很快上市。 无论是ＳＡＣＤ还是ＤＶＤ－Ａｕｄｉｏ碟片的物理格式和数据处理部分都与ＤＶＤ－Ｖｉｄｅｏ相当,价格绝对不是问题。特别是ＤＶＤ—Ａｕｄｉｏ设计时满口承诺可以被ＤＶＤ－Ｖｉｄｅｏ下兼容。后期出品的ＤＶＤ－Ｖｉｄｅｏ不少已把ＤＶＤ－Ａｕｄｉｏ标准中的多种格式编程在内,当然前题是播放没有加密的ＤＶＤ－Ａｕｄｉｏ碟片。还音基本设备已经有了,可碟片呢？除了少量试音碟或…     

在振动磨中PVC的降解及与MMA共聚反应的研究

考察了温度、振幅、钢球直径等对ＰＶＣ在振动磨中降解的影响，确定ＰＶＣ力化学降解为无规断链过程。用力化学方法在振动磨中合成了ＭＭＡ－ＰＶＣ共聚物，通过ＩＲ和ＮＭＲ对ＭＭＡ－ＰＶＣ共聚物结构进行了鉴定，研究了ＰＶＣ／ＭＭＡ配比和振磨时间对共聚反应产率及共聚物组成的影响。热失重分析、ＳＥＭ观察和冲击强度测定结果表明，ＭＭＡ－ＰＶＣ共聚物比ＰＶＣ具有较高的热稳定性；ＭＭＡ－ＰＶＣ共聚物对ＰＶＣ／ＰＨＭＡ（聚甲基丙烯酸己酯）体系有增容作用     

振磨降解制得的低分子量PVC对PVC增塑作用的研究

通过振靡降解制得了低分子量聚氯乙烯（ＰＶＣ）。通过Ｂｒａｂｅｎｄｅｒ塑化仪和力学性能测试研究了振磨降解制得的低分子量ＰＶＣ对高分子量ＰＶＣ的增塑作用和力学性能的影响，提出了增塑机理。实验结果表明，振靡降解制得的低分子量ＰＶＣ能增塑ＰＶＣ，显著改善ＰＶＣ的加工性能，提高ＰＶＣ的力学性能。     

低温PVA/PAM复合弹性膜的制作及性能研究

改性低温ＰＶＡ／ＰＡＭ（聚惭烯醇／丙烯酰胺）复合膜较低温ＯＶＡ膜机械强度更好。ＰＡＭ掺入ＰＶＡ后并不影响ＰＶＡ的低温结晶过程,低温ＰＶＡ／ＰＡＭ的性能相似于低温ＰＶＡ膜,由于ＰＶＡ／ＰＡＭ复合膜是ＰＶＡ物理交联与ＰＡＭ化学交联的互穿网络络结构,因此ＰＶＡ与ＰＡＭ的交联都可制约小分子这膜的速度。     

硼酸锌对PVC力学及阻燃性能的影响

通过ＴＧＡ、极限氧指数测定、ＳＥＭ和力学性能测定研究了ＰＶＣ／硼酸锌体系的热降解行为、阻燃性能和力学性能。研究结果表明，在ＰＶＣ中加入５％经偶联剂和振磨处理的硼酸锌，ＰＶＣ的冲击强度、拉伸强度和极限氧指数均得到了明显提高。ＰＶＣ中加入硼酸锌后，在ＰＶＣ热降解过程中、硼酸锌释放出的结合水能吸收ＰＶＣ放出的氯化氢，生成的氯化锌使ＰＶＣ脱氯化氢的反应活化能降低，反应速度加快，但使ＰＶＣ脱氯化氢后分子链倾向于形成反式多烯链结构，有利交联和炭化反应，使ＰＶＣ热失重明显减少，成炭量增加。硼酸锌可以用作ＰＶＣ的阻燃和抑烟剂。     

外源性野生型p53基因对人喉癌等肿瘤细胞生长抑制的实验研究

以反转录病毒Ｎ２Ａ为载体，使携带自身正调控序列的野生型ｐ５３基因反向插入Ｎ２Ａ两端ＬＴＲ间的Ｘｈｏｌ位点，获得了野生型ｐ５３基因反转录病毒重组体，建立了产病毒的ＰＡ３１７细胞系。用该细胞系产生的新鲜病毒颗粒感染有ｐ５３基因异常的人喉癌细胞系（Ｈｅｐ２）和纤维肉瘤细胞系（ＭＤＡＨ０４１），Ｓｏｕｔｈｅｒｎ－ｂｌｏｔ分析证实野生型ｐ５３基因反转录病毒前病毒能稳定整合在受体细胞染色体基因组上并有表达。感     

β-SiC production by reacting silica gel with hydrocarbon gas

A novel synthesis process, developed for producing high purity, submicron, non-agglomerated and low cost -SiC powders. The process is based on carbothermal reduction reaction of a novel coated precursor. The precursor is derived from a silica gel and a hydrocarbon gas and provides high contact area between reactants. This yields a better distribution of carbon within the silica gel and results in a more complete reaction and a purer product. The powders produced in this process have a low oxygen content (less than 0.8 wt.%), very fine particle size (0.1–0.3 m), narrow particle size distribution, non-agglomerated and are low cost. The sintering tests demonstrated that these powders can be pressureless-sintered to near theoretical density at about 2100°C in an inert atmosphere. No decarburization and no acid purification process was required before sintering.     

转水稻巯基蛋白酶抑制剂基因毛白杨的获得

通过农杆菌介导法将水稻巯基蛋白酶抑制剂基因导入毛白杨。毛白杨叶片到农杆菌共培养，采用卡那霉素３０ｍｇ／Ｌ筛选转化子获得抗性芽，然后转到卡那霉素５０ｍｇ／Ｌ的培养基上继续筛选，待转化芽长至１～２ｃｍ时切下移至卡那霉素５０ｍｇ／Ｌ的生根培养基上获得完整再生植株。通过ＰＣＲ检测和ＰＣＲ－Ｓｏｕｔｈｅｒｎ杂交证明水稻巯基蛋白酶抑制剂基因已整合到杨树基因组中。     

Evaluation of cross-linked chitosan microparticles containing acyclovir obtained by spray-drying

The aim of this study was to obtain microparticles containing acyclovir (ACV) and chitosan cross-linked with tripolyphosphate using the spray-drying technique. The resultant system was evaluated through loading efficiency, differential scanning calorimetry (DSC), thermogravimetric analysis (TG), X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), in vitro release and stability studies. The results obtained indicated that the polymer/ACV ratio influenced the final properties of the microparticles, with higher ratios giving the best encapsulation efficiency, dissolution profiles and stability. The DSC and XRPD analyses indicated that the ACV was transformed into amorphous form during the spray-drying process.     

Quantification of N-(deoxyguanosin-8-yl)-4-aminobiphenyl adducts in human lymphoblastoid TK6 cells dosed with N-hydroxy-4-acetylaminobiphenyl and their relationship to mutation, toxicity, and gene expression profiling

Gene expression profiles that are anchored to phenotypic endpoints may lead to the identification of signatures that predict mutagenicity or carcinogenicity. The study presented here describes the analysis of DNA adducts in the human TK6 lymphoblastoid cell line after exposure to N-hydroxy-4-aminobiphenyl, a mutagenic metabolite of 4-aminobiphenyl. A validated nano-LC microelectrospray mass spectrometry assay is reported for the detection and quantification of N-(deoxyguanosin-8-yl)-4-aminobiphenyl (dG-C8-ABP), the principal DNA adduct of 4-aminobiphenyl. Limits of quantification, based on a signal-to-noise ratio of 10:1, are determined to correspond to approximately 27 fg of dG-C8-ABP injected on-column. The assay has been used to measure the steady-state levels of the adduct in the human TK6 lymphoblastoid cell line as a function of dose (0.5, 1.0, and 10.0 microM) and time (2, 6, and 27 h) after exposure to N-hydroxy-4-aminobiphenyl. The levels of dG-C8-ABP adducts in the cells, ranging from 18 to 500 adducts in 10(9) nucleotides, were then correlated to cell toxicity, induced mutation at the TK (thymidine kinase) and HPRT loci, and gene expression profiling through microarray analysis. Cell cultures were evaluated for toxicity by growth curve extrapolation, mutation assays were performed on the HPRT and TK loci, and gene expression profiles were generated by analyses using microarray technology. In the mutation assay analysis, as the toxicant concentration increased, there was an increase in mutation fraction, indicating a direct correlation to metabolite dosing level and mutations occurring at these two loci. Statistical analysis of the gene expression data determined that a total of 2250 genes exhibited statistically significant changes in expression after treatment with N-OH-AABP (P < 0.05). Among the genes identified, 2245 were up-regulated, whereas 5 genes that had functions in cell survival and cell growth and, hence, could be indicators of toxicity, were down-regulated relative to controls. The results demonstrate the value of anchoring gene expression patterns to phenotypic markers, such as DNA adduct levels, toxicity, and mutagenicity.     

Mucoadhesive plasticized system of branched poly(lactic-co-glycolic acid) with aciclovir

Commercially available antibacterial semisolid preparations intended for topical application provide only short-term drug release. A sustained kinetics is possible by exploitation of a biodegradable polymer carrier. The purpose of this work is to formulate a mucoadhesive system with aciclovir (ACV) based on a solid molecular dispersion of this drug in poly(lactic-co-glycolic acid) branched on tripenterythritol (PLGA/T). The ACV incorporation into PLGA/T was carried out either by solvent method, or melting method, or plasticization method using various plasticizers. The drug–polymer miscibility, plasticizer efficiency and content of residual solvent were found out employing DSC. Viscosity was measured at the shear rate range from 0.10 to 10.00?s^?1 at three temperatures and data were analyzed by Newtonian model. The mucoadhesive properties were ascertained in the tensile test on a mucin substrate. The amount of ACV released was carried out in a wash-off dissolution test. The DSC results indicate a transformation of crystalline form of ACV into an amorphous dissolved in branched polyester carrier, and absence of methyl formate residuals in formulation. All the tested plasticizers are efficient at T_g depression and viscosity decrease. The non-conventional ethyl pyruvate possessing supportive anti-inflammatory activity was evaluated as the most suitable plasticizer. The ACV release was strongly dependent on the ethyl pyruvate concentration and lasted from 1 to 10 days. The formulated PLGA/T system with ACV exhibits increased adhesion to mucosal hydrophilic surfaces and prolonged ACV release controllable by degradation process and viscosity parameters.     

Development of a liposome microbicide formulation for vaginal delivery of octylglycerol for HIV prevention

The feasibility of using a liposome drug delivery system to formulate octylglycerol (OG) as a vaginal microbicide product was explored. A liposome formulation was developed containing 1% OG and phosphatidyl choline in a ratio that demonstrated in vitro activity against Neisseria gonorrhoeae, HSV-1, HSV-2 and HIV-1 while sparing the innate vaginal flora, Lactobacillus. Two conventional gel formulations were prepared for comparison. The OG liposome formulation with the appropriate OG/lipid ratio and dosing level had greater efficacy than either conventional gel formulation and maintained this efficacy for at least 2 months. No toxicity was observed for the liposome formulation in ex vivo testing in a human ectocervical tissue model or in vivo testing in the macaque safety model. Furthermore, minimal toxicity was observed to lactobacilli in vitro or in vivo safety testing. The OG liposome formulation offers a promising microbicide product with efficacy against HSV, HIV and N. gonorrhoeae.     

Different sets of reliability data and success criteria in a probabilistic safety assessment for a plant producing nitroglycol

The lack of plant-specific reliability data for probabilistic safety assessments usually makes it necessary to use generic reliability data. Justifiably different assessments of plant behaviour (success criteria) lead to different models of plant systems. Both affect the numerical results of a probabilistic safety assessment. It is shown how these results change, if different sets of reliability data and different choices of success criteria for the safety system are employed. Differences in results may influence decisions taken on their basis and become especially important if compliance with a safety goal has to be proved, e.g. a safety integrity level. For the purpose of demonstration an accident sequence from a probabilistic safety assessment of a plant producing nitroglycol is used. The analysis relies on plant-specific reliability data so that it provides a good yardstick for comparing it with results obtained using generic data. The superiority of plant-specific data, which should of course be acquired, cannot be doubted. Nevertheless, plant safety can be improved even if generic data are used. However, the assignment to a safety integrity level may be affected by differences in both data and success criteria.     

螺旋藻多糖抗HSV-1作用的体外实验研究

报道从钝顶螺旋藻中提取的一种水溶性多糖类化合物，即钝顶螺旋藻多糖（PSP），在培养细胞内抗单纯疱疹病毒1型（HSV－1）作用的研究。以不同剂量的PSP作用于病毒复制周期的各个阶段，以病毒半数感染量（TCID50），细胞病变（CPE），蚀斑形成（PFU），MTT染色细胞保护率（MTT法）及核酸分子杂交作为评价指标，判断药效。结果表明：PSP对Vero细胞毒性极低；对HSV－1无直接灭活作用，可干扰病毒向宿主细胞吸附，且经PSP预处理的细胞，能明显阻滞病毒产生细胞病变；PSP可有效地抑制病毒复制，但不影响病毒的释放；PSP可明显抑制HSV－1糖蛋白gG mRNA的表达。提示PSP抗病毒靶位在于阻断病毒吸附和抑制感染细胞内病毒的复制及抑制HSV－1糖蛋白gG基因的转录。