仿贻贝黏附性多巴胺的研究与应用进展

海洋贻贝类生物通过足丝分泌的黏附蛋白,具有高强度、高韧性、防水性以及极强黏附性等特点,可以使其黏附在几乎所有基底材料上。大量研究表明,3,4-二羟基-L-苯基丙氨酸(多巴,DOPA)是海洋贻贝类生物分泌的相关黏附蛋白中的重要组成部分。而且,贻贝黏附蛋白所具有的这种超强黏附能力,主要与多巴中特有的分子结构以及其与基底材料的相互作用方式等相关。多巴胺作为多巴衍生物的重要成员,具有与多巴相似的结构和性质,同样可以实现对基材表面的黏附,因而引起了研究人员的极大关注。本文综述了多巴胺的结构、性质、聚合机理以及它们在材料学、仿生学、生物医学等不同领域的应用现状。     

氧化超声降解聚乙烯醇制备接枝炭黑

首次将超声波降解聚合物原理应用于炭黑的接枝过程中，在超声波和H2O2的共同作用下，使聚乙烯醇(PVA)降解，产生大分子自由基，进而被炭黑表面捕获，实现接枝，考察超声波和H2O2对提高炭黑分散性的贡献，并借助Raman光谱、透射电镜(TEM)等测试手段对接枝炭黑进行了表征，结果表明：聚乙烯醇降解过程中生成的高分子自由基被炭黑捕捉，获得了聚乙烯醇接枝的炭黑，该炭黑具有很好的分散稳定性；超声波对提高炭黑分散性的作用远优于H2O2；接枝炭黑在水中的聚集程度明显降低。     

仿贻贝蛋白聚合物在防污涂层中的应用进展EI北大核心CSCD

贻贝蛋白对不同基材表面都具备优异的黏附能力。研究表明,将贻贝蛋白的功能元-邻苯二酚基团引入到合成高分子中(仿贻贝蛋白聚合物)可有效模拟贻贝蛋白的功能特性。利用这种功能特性,通过在仿贻贝蛋白聚合物中引入防污组分可实现对不同基材的普适性强力黏附,是当前防污涂层领域中的研究热点之一。文中以仿贻贝蛋白聚合物的主链骨架的类型为主线,综述了近年来国内外仿贻贝蛋白聚合物在防污涂层中的应用进展,以期为研究人员探索新型的功能化贻贝仿生材料提供有益的借鉴和参考。     

可注射原位凝胶的制备及性能表征

以聚琥珀酰亚胺(PSI)为原料,利用酰亚胺基开环反应,首先制备得到α,β-聚(N-羟乙基)-DL-天门冬酰胺(PHEA),再与丙烯酰氯反应,制备得到接枝丙烯酰胺基α,β-聚(N-羟乙基)-DL-天门冬酰胺(PHA).通过FT-IR、NMR对其结构进行了表征.这种大分子单体的溶液可在人体温度下发生原位的交联反应,形成凝胶.可通过改变接枝率、大分子单体浓度等因素控制凝胶化时间.当选用质量浓度为0.1g/mL的PHA1#(接枝率为19.6%)单体、交联剂质量浓度为4mg/mL、引发剂浓度为20mmol/L时,凝胶化时间为90s.该凝胶具有可注射性和疏松的大孔结构,并且凝胶化时间可控,在模拟体液中有轻微溶胀,是较理想的治疗干眼症注射式材料.     

聚乙烯醇接枝丝素蛋白的制备和性能

利用环氧氯丙烷通过非均相共价接枝反应将丝素蛋白分子接枝到聚乙烯醇大分子上,制备了以丝素蛋白分子为支链结构、以聚乙烯醇为主链的新型大分子聚乙烯醇接枝丝素(PVA-g-SF)。介绍了制备反应原理,通过FT-IR、DSC测试对接枝反应进行了验证,并通过单因子实验分析讨论了反应温度、反应时间、丝素溶液浓度对丝素接枝效率的影响,优选出了最佳反应条件。最终发现:丝素蛋白分子成功接枝到了聚乙烯醇分子上,并且当反应温度为40℃、反应时间为4h、丝素溶液浓度为10%时,丝素蛋白的最大接枝效率可达13.54%。     

高透明度聚乙烯醇水凝胶的制备、表征及透明机理研究

用二甲基亚砜(DMSO)水溶液通过冷冻/解冻法制备了高透明度聚乙烯醇(PVA)水凝胶,使用差示扫描量热仪(DSC)、紫外吸收光谱、力学性能分析仪、紫外-可见分光光度计等分析了DMSO浓度对聚乙烯醇水凝胶透光率的影响,并表征了PVA水凝胶的含水率、结晶度、力学性能等性质.结果表明,用含量为80%(质量分数)的DMSO水溶液制备的PVA水凝胶得到了高达(99.8±0.2)%透明度,其抗拉强度达到3MPa以上,断裂拉伸率＞600%.研究发现,DMSO与水形成的1DMSO/2H2O网络结构能够限制PVA分子在三维方向的结晶,同时能够促进二维方向PVA晶体的生长.当DMSO含量为80%时,溶液中DMSO与水的比例略＞1:2,存在少量未形成1:2网络结构的DMSO分子,该分子与PVA羟基形成氢键限制了PVA分子在二维方向的结晶,最终导致PVA水凝胶中PVA晶体的体积最小、PVA晶体的数目最多,从而得到了最高的水凝胶透明度和较好的力学性能.     

聚乙烯醇接枝阳离子聚丙烯酸酯的无皂乳液聚合及表征

以聚乙烯醇(PVA)为分散剂,丙烯酸丁酯(BA)、苯乙烯(St)、甲基丙烯酰氧乙基三甲基氯化铵(DMC)、甲基丙烯酸(MAA)、丙烯酸十八酯(ODA)为原料,采用无皂乳液聚合方法合成了聚乙烯醇接枝阳离子聚丙烯酸酯多元无皂乳液。对聚合物的结构、组成及性质进行了表征,研究了共聚物乳液的粒径及分布、黏度、流变性和涂膜力学性质。结果表明,聚乙烯醇接枝阳离子聚丙烯酸酯无皂乳液平均粒径为140.9 nm,粒径分布在120 nm~160 nm,黏度为10.2 mPa.s左右,涂膜拉伸强度可达5.3 MPa。     

乙烯-乙烯醇基大分子型强化交联剂的合成与应用

通过酯化反应制备了乙烯-乙烯醇.丙烯酸(EVOH-AA)接枝型材料,并用红外光谱对接枝产物进行了袁征.凝胶抽提结果表明,由于乙烯基双键的引入,难于辐射交联的EVOH在较低的辐射剂量下就可以辐射交联.具备成为强化交联剂的可能.通过研究改性EVOH与聚乳酸共混物的辐射效应,发现聚乳酸进入交联网格,证明改性EV0H具有一定的...     

贻贝仿生构建聚乳酸多层复合薄膜及其性能

为了提高聚乳酸(PLA)薄膜的抗菌性、紫外光屏蔽等活性包装功能,本工作受到贻贝仿生学原理启发,利用多巴胺(DA)在PLA薄膜表面发生氧化自聚形成聚多巴胺(PDA)涂层(PLA-P),再利用PDA的儿茶酚基团将Ag+还原成Ag纳米粒子(AgNPs)负载在PDA上( PLA-PA),进一步接枝上氟硅烷(PLA-PAF),从而成功制备出PLA多层复合薄膜,并研究了不同涂层对PLA多层复合薄膜结构和性能的影响.结果表明,PLA多层复合薄膜的表面涂层结构致密,AgNPs均匀负载在PLA上,尺寸约为65 nm,表面质量分数达到38%;相比纯PLA薄膜,PLA-PAF的拉伸强度(99. 1 MPa)和断裂伸长率(16. 1% )仅分别降低了5. 9%和7. 5% ,热稳定性略微提高,水接触角达到117. 8°,疏水性得到显著提高;PLA基材经过原位还原负载AgNPs和接枝氟硅烷之后,PLA-PAF的抗菌率达到了99. 5% ,紫外光屏蔽性显著提高,而且由于其较好的疏水性,在实际使用时能够减少细菌的黏附和滋生,进一步提升抗菌活性.相比完全采用成本较高的AgNPs单一抗菌改性,基于贻贝仿生改性的抗菌涂层将在PLA活性包装领域具有较好的研究意义.     

儿茶酚基聚合物-金属复合水凝胶的制备及性能

儿茶酚基化合物具有化学多功能性,易与过渡金属(如Fe3+)形成有效的配位化合物,在医疗、分析及环境领域具有广阔的应用前景。文中以聚乙烯醇为原料,用含儿茶酚基的3,4-二羟基苯丙氨酸(DOPA)修饰改性聚乙烯醇(PVA),得到聚合物PVA-DOPA,再通过儿茶酚基的氧化络合能力与Fe3+等金属离子作用,制备具有p H响应性的非共价键交联金属复合水凝胶,其结构与组成用核磁共振氢谱、傅里叶变换红外光谱等进行表征。流变分析PVA-DOPA与金属离子络合水凝胶的储能模量约为21000Pa;当频率不变时,通过检测水凝胶的储能模量随振幅振荡力的变化,证明制得的水凝胶具有自修复性。此外,PVA-DOPA与金属离子的络合能力具有很强的p H依赖性,碱性介质中DOPA与金属离子形成三配位;而酸性或中性介质中,则为一/二配位,因而,可实现PVA-DOPA与金属离子络合的p H响应可逆性。这种聚合物及其凝胶有望应用于涂层、吸附分离和生物医药领域。     

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.