双还原敏感的混合胶束用作为抗肿瘤药物的载体

通过酯化缩聚制备了含双硒键的聚合物聚乙二醇-缩-二硒二(十一酸)(PEG-SeSe-PEG),用核磁和红外确证了其结构。临界胶束浓度(CMC)结果表明,PEG-SeSe-PEG与两亲聚合物聚己内酯-二硫键-b-聚甲基丙烯酸二乙胺基乙酯/聚磺酸甜菜碱(PCL-SS-PDEA-PS)一样能够形成胶束,并且两者能形成混合胶束。用动态光散射和扫描电镜对胶束的粒径和还原敏感进行了研究。粒径变化显示混合胶束有双还原敏感性。用紫外分光光度计测定了胶束对疏水性抗癌药物模型姜黄素的载药量(DLC)和包封率(DLE)。PCL-SS-PDEA-PS占80%的双还原敏感胶束(混合胶束E)的载药量和包封率最高。体外释药结果显示,双还原敏感胶束在还原环境中的释药速率快于非还原环境。体外细胞毒性结果表明,双还原敏感胶束比PCL-SS-PDEA-PS胶束的细胞相容性好,而且载药E胶束能最好地抑制Hela细胞生长。     

叶酸受体靶向的聚乳酸共聚物胶束的制备及性质研究

叶酸偶联的羟脯氨酸-乳酸共聚物(PLLA-PHpr-FA)是一种新型的叶酸受体靶向生物降解聚合物,研究PLLA-PHpr-FA自组装形成胶束的能力及胶束的性质。临界胶束浓度(CMC)用芘荧光探针测定,结果表明,CMC很低并依赖于乳酸/羟脯氨酸的比例。透射电子显微镜(TEM)显示共聚物胶束呈现典型的核/壳结构。动态激光光散射(DLS)测定粒径及粒径分布结果显示,粒径受乳酸/羟脯氨酸比例和丙酮量调控,但粒子几乎不受稀释的影响。用紫外分光光度法测定胶束的载药量和包封率表明,共聚物胶束对疏水性药物的包载较好。因此,PLLA-PHpr-FA胶束可以作为肿瘤靶向的药物载体。     

普朗尼克胶束用于抗癌药物阿霉素的负载和释放

为了研究阿霉素胶束中药物的存在形式及其与胶束释药行为的关系,以不同类型的普朗尼克胶束为载体材料制备了3种阿霉素胶束。普朗尼克载药胶束首先由阿霉素盐酸盐和脱氧胆酸钠通过静电相互作用形成复合物,然后通过亲疏水性作用封装到普朗尼克胶束的疏水段形成。以载药量和包封率为评价指标,动态光散射法测定其粒径大小及其分布、透析法测定载药胶束的体外释放行为。结果表明,制备的普朗尼克F127,F128,F68胶束的载药量分别为(0.15±0.11)%,(0.16±0.07)%和(0.17±0.1)%,包封率分别为(3.03±0.24)%,(3.11±0.15)%和(3.36±0.02)%。载药胶束的粒径分布均匀。在690 min内累计释放率均能达到70%以上,且无显著性差异。本文成功制备了均一、稳定的普朗尼克载药胶束,研究了不同普朗尼克载药胶束的药物释放行为,为药物输送系统提供理论依据和参考。     

β-环糊精/O-羧甲基壳聚糖纳米粒对光敏性药物的联合保护

为提高疏水性光敏药物硝苯地平(NF)的光稳定性,用共沉法制得了NF/β-环糊精(NF/β-CD)包合物,再通过离子交联法制得了NF/β-环糊精/O-羧甲基壳聚糖(NF/β-CD/O-CMC)纳米粒。用差示扫描量热仪和X射线衍射仪对NF/β-CD包合物进行了表征;用紫外-可见分光光度计、X射线衍射仪、激光粒度仪和扫描电子显微镜对NF/β-CD/O-CMC纳米粒进行了分析。结果表明,纳米粒包封率和载药量分别为82.38%和18.41%,纳米粒呈多面体形,分散均匀,平均粒径273.80 nm,Zeta电位-37.6 m V,多分散指数(PDI)0.086。紫外光降解实验显示,β-CD包合物对NF有一定的光降解保护作用,β-CD/O-CMC纳米粒中的NF初始1 h降解较快,随后较慢,4 h降解率达到42.43%,此后基本不变,其光降解保护作用明显优于β-CD包合物,具有更好的光降解联合保护作用。     

线型-超支化结构两亲性嵌段聚合物mPEG-b-hPCL的合成、表征、自组装行为及体外释药行为的研究

通过开环聚合、酯化反应等方法制备聚乙二醇-聚己内酯(PEG-b-hPCL)线性-超支化嵌段共聚物,利用核磁(1 H-NMR)、凝胶渗透色谱(GPC)等表征。DSC结果表明超支化PCL的熔程较长;测定临界胶束浓度(CMC),发现随着聚合物中PCL含量增加,胶束CMC下降;在水、甲醇中自组装,发现水中聚集体粒径为300nm左右,大于甲醇中的聚集体;通过透射电镜(TEM)发现水相聚集体为胶束,甲醇相聚集体为纳米颗粒。以吲哚美辛为药物,研究PEG-b-hPCL胶束的载药能力,其载药量在15%左右,包封率在33%左右,36h后累积释放量有所不同,较高PCL含量的胶束的药物释放量较少。     

氧化还原敏感型胶束的构建和药物控释性能EI北大核心CSCD

采用3,3'-二硫代二丙酸、乙酰氯、N-Boc-乙醇胺、ε-己内酯、聚乙二醇单甲醚等为原料,通过分子内脱水、酰化、开环聚合、缩合等一系列反应制备了以聚乙二醇单甲醚(mPEG)为亲水端,聚己内酯(PCL)为疏水端,中间含有二硫键链接的两亲聚合物——mPEG-SS-PCL。通过核磁共振氢谱、傅里叶变换红外光谱对聚合物的结构进行表征;以阿霉素(DOX)为模型药物,探讨胶束载药性能和氧化还原敏感性能。并通过MTT法评价了聚合物的细胞毒性。研究结果表明,mPEGSS-PCL可自组装形成胶束,该胶束粒径分部均匀,外表圆整,粒径约为190 nm,其结构具有良好的氧化还原敏感性;胶束的载药量为10. 0%,载药稳定性良好,且具有显著的药物控制释放性;此外,胶束在细胞水平表现为良好的生物安全性。     

氧化还原敏感型胶束的构建和药物控释性能

采用3,3'-二硫代二丙酸、乙酰氯、N-Boc-乙醇胺、ε-己内酯、聚乙二醇单甲醚等为原料,通过分子内脱水、酰化、开环聚合、缩合等一系列反应制备了以聚乙二醇单甲醚(mPEG)为亲水端,聚己内酯(PCL)为疏水端,中间含有二硫键链接的两亲聚合物——mPEG-SS-PCL。通过核磁共振氢谱、傅里叶变换红外光谱对聚合物的结构进行表征;以阿霉素(DOX)为模型药物,探讨胶束载药性能和氧化还原敏感性能。并通过MTT法评价了聚合物的细胞毒性。研究结果表明,mPEGSS-PCL可自组装形成胶束,该胶束粒径分部均匀,外表圆整,粒径约为190 nm,其结构具有良好的氧化还原敏感性;胶束的载药量为10. 0%,载药稳定性良好,且具有显著的药物控制释放性;此外,胶束在细胞水平表现为良好的生物安全性。     

甘草次酸(β)海藻酸钠-羧甲基壳聚糖复合凝胶珠的制备及体外释放

以海藻酸钠-羧甲基壳聚糖(ALG-CMC)为载体材料,甘草次酸(β)(GA)为模型药物,采用滴制法制备了ALG-CMC负载GA的复合凝胶珠。采用体视显微镜与扫描电镜(SEM)观察了凝胶珠的外观形貌,考察了凝胶珠的溶胀性能和体外释药行为,以及CaCl2浓度对凝胶珠的包封率和载药量的影响。结果表明,湿态凝胶珠形态规整、粒径分布均匀,平均粒径约2900μm,包封率最高达85.7%,载药量为18.0%;CaCl2浓度对包封率和载药量几乎无影响;在pH=1.2的HCl溶液中凝胶珠溶胀率小、累积释放率低;在pH=7.4的磷酸盐缓冲(PBS)溶液中凝胶珠溶胀率大、累积释放率高。滴制法制备ALG-CMC凝胶珠条件温和、不接触有机溶剂,凝胶珠具有pH敏感性且能有效载药。该体系有可能成为GA的给药载体材料。     

5-氟尿嘧啶载药微球的制备工艺及性能研究

以PLA为载体材料,以5-Fu为模型药物,制备5-Fu/PLA载药微球,通过正交设计优化微球制备工艺.另外,检测了载药微球的回收率、稳定性、缓释性能等物理性质.用紫外分光光度计测定药物含量,激光粒度仪分析粒径. 结果表明,载药微球的平均粒径为(133.2±32.5)nm,平均包封率为(11.3±5.0)%,缓释时间延长至80～100h,具有良好的缓释功能.     

载异烟肼聚己内酯微球的制备及其性质研究

采用O/O溶剂挥发法制备载异烟肼聚己内酯微球。系统考察了活性剂浓度、内外油相体积、投药量对微球粒径、载药量和包封率的影响。结合内外油相初始粘度分析载药微球成球性,用IR、XRD、SEM对微球化学结构、结晶状态和表面形貌进行表征。通过优化得到平均粒径为28.73μm、载药量为2.36%、包封率为49.58%、外观圆整、表面多孔的载药微球。与O/W溶剂挥发法制备微球对比表明,O/O法有效地提高了载异烟肼聚己内酯微球载药量与包封率,是包覆亲水性小分子药物的可行方法,该载药微球可望用于骨和关节结核病的缓释治疗。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.