羧甲基壳聚糖/纤维素共混膜的制备及性能研究

低温冷冻条件下,将羧甲基壳聚糖与用氢氧化钠-尿素-硫脲体系溶解的纤维素共混制膜,所制膜可用于止血、保湿、促进伤口愈合等功能的新型敷料.经红外光谱、扫描电镜、透射比分析,当共混膜中羧甲基壳聚糖含量小于30%时,CMCT与纤维素形成的膜具有较好的相容性.当达30%时,共混膜的断裂强力达到最大值73MPa,提高了近52.1%.共混膜的断裂伸长率与吸湿保湿率随着羧甲基壳聚糖含量的增加而增大,且共混膜对金黄色葡萄球菌和大肠杆茵具有良好的抑茵性.并具有较好的力学性能、吸湿保湿性.     

纤维素/壳聚糖共混膜的研究进展

纤维素和壳聚糖共混膜材料相较于单一膜材料,机械性能、生物相容性和抗菌性均会有较大提高。综述了纤维素/壳聚糖共混膜的制备及改性研究进展,并对纤维素/壳聚糖共混膜作初步的探讨和展望,以期为今后纤维素/壳聚糖共混材料的制备工艺和应用发展提供一些参考。     

多糖类天然高分子/PVA可生物降解共混膜的研究进展

目的综述天然高分子(淀粉、羧甲基纤维素、壳聚糖、海藻酸钠和木质素)与聚乙烯醇(PVA)复合制备可生物降解共混膜的方法及性能的研究进展。方法分类讨论淀粉、羧甲基纤维素、壳聚糖、海藻酸钠、木质素分别与PVA进行共混制备共混膜的方法及应用。结果总结了多糖类天然高分子/PVA共混膜的研究与应用进展,并指出了该类共混膜今后发展的方向。结论多糖类天然高分子/PVA可生物降解共混膜的研究是目前科研的热点之一,该共混膜对降低环境污染和节约能源具有重要的意义,具有广阔的应用前景。     

纤维素/壳聚糖共混纳滤膜的制备及其染料脱盐性能研究

纤维素因其优良的机械性能、亲水性和成膜性而成功地应用于纳滤膜制备.但纯纤维素纳滤膜表面呈负电性,对低分子量水溶性染料和Na_2SO_4均具有高的截留率,不利于染料中Na_2SO_4的脱除.将荷正电的壳聚糖和纤维素共混,以离子液体1-乙基-3-甲基咪唑醋酸盐(EMIMAc)和二甲基亚砜DMSO为溶剂,水为凝固浴,无纺布为支撑层,采用相转化法,成功制备了纤维素/壳聚糖共混弱正电纳滤膜.结果表明,当纤维素和壳聚糖质量比为1∶1时,制备的共混纳滤膜分离性能最优.该膜在0.5MPa的错流条件下,对直接染料的截留率较高,如刚果红的截留率为99.99%;对活性染料(活性黑5、活性蓝19)的截留率也可达到80%~90%;而膜对无机盐截留率均较低,NaCl和Na_2SO_4的截留率分别在10%和1%以下.上述研究结果表明,该膜可实现染料和盐的高效分离.     

再生丝素/羧甲基壳聚糖膜的制备和性能

用二次冷冻干燥法制备出以戊二醛为交联剂的再生丝素/羧甲基壳聚糖复合材料,研究了不同配比的戊二醛/丝素/羧甲基壳聚糖膜的理化性质。结果表明:这种再生丝素/羧甲基壳聚糖复合材料具有联通的三维多孔结构,孔径分布均匀,丝素与羧甲基壳聚糖之间形成分子间氢键,相容性好;丝素与羧甲基壳聚糖的质量比为1:1,戊二醛的含量为0.20%时共混材料的力学性能最优,且热稳定性较好。植入皮下结果表明,这种复合材料具有良好的生物降解性和生物相容性。     

废纸纤维素/壳聚糖膜的制备及性能

为增强壳聚糖膜的力学性能,制备了废纸纤维素/壳聚糖膜.以包装废弃瓦楞纸为原料,通过碱处理和漂白处理得到再生纤维素,再以不同组分与壳聚糖制备成膜,并对不同原料膜进行形态观察和力学性能检测.研究结果表明:废纸纤维素呈丝状,纤维直径约为15～20μm,结晶度较原始瓦楞纸有大幅提高;当在质量分数为2％的壳聚糖溶液中添加相对质量分数为5％的废纸纤维素时,废纸纤维素/壳聚糖膜力学性能最好,最大拉伸强度达52.3 MPa,断裂伸长率超过20％,纤维素分布均匀.     

壳聚糖-醋酸纤维素共混膜的制备及其渗透汽化性能

研究了壳聚糖（ＣＳ）与醋酸纤维素（ＣＡ）渗透汽化共混膜的制膜条件，测定了该膜对乙醇－水混合液的渗透汽化性能及平衡溶解吸附性能实验表明，壳聚糖－醋酸纤维素共混膜对乙醇质量分数为５０％～９５％的乙醇－水溶液具有良好的渗透汽化分离性能     

玉米全粉/PVA共混膜的制备及性能

目的利用玉米全粉与聚乙烯醇(PVA)制备共混膜,研究其性能结构,以期替代传统塑料包装袋,缓解白色污染的危害。方法在三乙醇胺和羧甲基纤维素的作用下通过溶液浇铸法制备玉米全粉/PVA共混膜,考察PVA含量对共混膜力学性能、吸湿性能及水蒸气透过性能的影响。结果共混膜的拉伸强度、断裂伸长率和撕裂强度均随PVA含量的增加而升高,吸湿率和水蒸气透过率随PVA含量的增加而降低,吸水后共混膜的力学性能有所下降,显微观察表明,PVA含量的增加可提高共混系统的相容性,PVA在原料基体中质量分数为40%~60%时的共混膜拉伸强度可达10 MPa以上,吸湿率小于82%,水蒸气透过率约为12×10^-5 g/(mm·d)。结论该共混膜有一定抗水蒸气和油渗透的功能,基本可满足普通包装材料的要求。     

壳聚糖—醋酸纤维互共混膜的制备及其渗透汽化性能

研究了壳聚糖（ＣＳ）与醋酸纤维素（ＣＡ）渗秀汽化共混膜的制膜条件，测定了该膜对乙醇－水混合液的渗透汽化性能及平衡溶解吸附性能、实验表明，壳聚糖－醋酸纤维素共混膜对乙醇质量分数为５０－９５％的乙醇－水溶液具有良好的渗透汽化分离性能。     

羟丙基纤维素/壳聚糖共混膜的制备与性能

采用溶液共混法制备了一系列不同比例的羟丙基纤维素(HPC)/壳聚糖(CS)共混膜,研究了羟丙基纤维素含量对共混膜的力学性能、吸湿性能、透光性能等的影响。结果表明,HPC/CS共混膜的断裂伸长率随着HPC含量的增加而增加,而拉伸强度则先提高后下降,且在含量为40%时共混膜的拉伸强度达到最大;共混膜在可见光区300nm~800nm的最大透光率均大于70%;随着HPC含量的增加共混膜的吸水率大大降低。     

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 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.     

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.     

Early ironwork in Biscay: Survey,excavation, experimentation and materials characterization. An integral study of the mountainside ironworks (ferrerías de monte or “haizeolak”)

ABSTRACT

The production of iron in Biscay (Basque Country, Spain) has been a hallmark of this territory of the North of the Iberian Peninsula throughout its history. The Archaeology team of the Basque Country Mining Museum has spent 13 years, so far, studying the origins of this activity through the evidences left at the old pre-hydraulic iron production workshops known as mountainside ironworks (ferrerías de monte) or haizeolak. It has catalogued 170 archaeometallurgical sites of this type in Biscay, and the archeological excavation of some of them has led to the knowledge of the different stages of the production process that took place in these workshops. The team has also experimentally reproduced the work carried out in a mountainside ironworks from the High Middle Ages, and it has currently started the characterization process of this type of activity through the study of the collected materials.     

Mechanism Study on the Wear of CrAlTiN Coated High-Speed Steel Twist Drills Under Dry Cutting Conditions

As demands about environment protection are growing up, dry cutting technology is getting more and more concerns from all over the world. Main works performed here are study on dry cutting performances and wear mechanisms of M2high-speed steel (HSS) twist drills with CrAlTiN multicomponent coatings, which was deposited using magnetron sputter ion plating system, in drilling 45 and 30CrMnSiA steel, and their comparisons to those in drilling the same steel but using monolayer CrN and commercial TiN coated drills. Drilling performances of drills are evaluated mainly through the measurements of width on outer corner flank land and the cutting forces. Results show that performances of CrAlTiN coated drills are better than those of monolayer CrN and TiN coated drills. In drilling 45 and 30CrMnSiA steel, the average tool life of the CrAlTiN coated drills are 17.2 and 11.8 times higher than those of the uncoated drills. Observing wear of the drill with scanning electronic microscope, results show that there is no crack or spallation of the CrAlTiN coatings in wear zones. Main mechanism of the wear here is adhesion.     

Study on Bond Ability of Arc-Spraying Coatings with Different Surface Pretreatment on Cast-Iron

Arc spraying coatings are widely used in various applications, but uncommon in cast iron substrate. Different surface pretreatment technology is tested on substrates of gray cast iron. Surface roughness and residual stress were measured by TR200 and X-ray diffraction analyzer. Influence of different surface pretreatment methods ( dry blasting and fusebond) on roughness and residual stress was analyzed. The arc-sprayed coatings of wire 3Cr13 (φ2mm) on gray cast iron substrate is studied. The microstructure and interface of bonding layer were observed by SEM. The bond strength was taken by tensile test. Results show that bond strength with grit blasting is higher than fuse-bond; it is feasible to make wire 3Cr13 coating with arc spraying on cast iron substrate roughened by grit blasting.     

Structural Characteristics of TiO2 Ceramic Coating by Micro-Plasma Oxidation

TiO2 ceramic coatings with thickness of 20 μm were formed on the surface of pure titanium by micro-plasma oxidation. Their micro-structures were investigated by by using X-ray diffraction and their surface images were detected by using scan electronic microscope. There were three kinds of TiO2 coatings, pure anatase type TiO2 phase, mixed phases consisted of rutile type TiO2 phase and anatase type TiO2 phase, pure rutile type TiO2 phase. The coating surface with the pure anatase type TiO2 phase is rough, while the coating surface with the pure rutile type TiO2phase is smooth. The upper coating surface with the mixed type TiO2 phases is anatase type TiO2 structure and the subsurface of the TiO2 coating is rutile type TiO2structure.     

Evaluation of fatigue life of steel using steel grain size

The insightful discussion of the relationship between the construction of metallographic and fatigue life and proposition of mathematical relationships describing this relationship was conducted in the paper. This paper presents a method for estimating the fatigue life, based on the construction of the microstructural material taking into account the grain size and the participation of ferrite and pearlite phase.