漆酶催化黄麻-g-丁子香酚接枝丙烯酰胺亲水化改性

研究了漆酶催化桥接过渡单体丁子香酚的黄麻织物接枝丙烯酰胺的改性方法,考察了改性黄麻的亲水性。元素分析证明漆酶/t-BHP体系能催化引发黄麻-g-丁子香酚上的CC双键与丙烯酰胺发生聚合反应,利用微量凯氏定氮法测定了黄麻-g-丁子香酚接枝丙烯酰胺的接枝率,并对反应条件进行了优化。热失重(TG)分析表明改性黄麻织物耐热性提高;静态接触角、水滴润湿时间表明改性黄麻织物亲水性显著提高。     

黄麻纤维酶促接枝疏水化改性及其增强PLA复合材料研究

利用漆酶催化氧化酚羟基产生自由基进而耦合交联的特性,将单体没食子酸月桂酯(DG)接枝到黄麻纤维中的木质素上,赋予黄麻纤维表面疏水性,而后将改性黄麻纤维与聚乳酸(PLA)树脂熔融混合、挤出注塑制备DG接枝黄麻纤维/PLA复合材料。经红外光谱、元素分析证实,DG在漆酶的催化作用下接枝到黄麻纤维上,使黄麻纤维的疏水性提高,接触角由104.3°增至121.4°,平均水滴润湿时间由5.2s增至19.9min,平衡吸湿率由9.55%降至8.95%。疏水化改性有利于黄麻纤维在PLA树脂基体中的分散,并且纤维与基体间的界面相容性得到改善。实验表明,DG接枝黄麻纤维/PLA复合材料的拉伸强度和弯曲强度较黄麻纤维/PLA复合材料分别提高47.5%和35.9%,同时拉伸应变和弯曲应变分别提高24%和31.6%。     

腰果酚-甲苯二异氰酸酯接枝黄麻纤维研究

表面接枝是解决黄麻纤维与树脂不相容关键技术之一。采用高活性的甲苯二异氰酸酯(TDI)将腰果酚(CNSL)接枝于黄麻纤维。通过接枝前后黄麻纤维的红外光谱(FT-IR)、光电子能谱(XPS)、扫描电子显微镜(SEM)、吸水率、接枝率、热分析的表征。研究表明,CNSL-TDI接枝到黄麻纤维上,接枝率为15.27%;吸水性能得到改善,吸水2d后的吸水率最大值为17.7%;耐热性得到提高,在350℃时,未经CNSL-TDI接枝的黄麻纤维失重率为61.27%;而经CNSL-TDI接枝的黄麻纤维失重率为27.84%。     

生物酶催化接枝芳纶纤维和复合材料的界面性能

用辣根过氧化物酶(HRP)作为生物活性酶催化剂在芳纶纤维纤维表面上进行接枝反应,生成一层带有活性官能团烯丙基缩水甘油醚的包覆层,研究了生物酶催化接枝反应对芳纶纤维综合性能的影响。结果表明,生物酶能有效地催化纤维上的接枝反应,酶的浓度影响单体在纤维上的接枝率。随着酶浓度的提高有更多的单体接枝到纤维上,使表面极性官能团含量、表面自由能和表面粗糙度大幅度地提高,使纤维与树脂之间的界面结合强度增强。同时,与原有的纤维改性方法相比,生物酶催化接枝法基本保持了芳纶纤维的优异热学和力学性能。     

漆酶催化麻织物固定化溶菌酶及其抗菌性能

利用漆酶对木质素的催化作用将溶菌酶接枝到富含木质素的麻织物上,赋予其抗菌性。通过考马斯亮蓝染色法证明了溶菌酶的接枝,对两种不同木质素含量的织物(棉/亚麻混纺织物、黄麻织物)的接枝效果进行了比较,并应用扫描电镜(SEM)考察了接枝后麻纤维表面形态,研究了溶菌酶固定化后麻织物的抗菌性能和耐洗稳定性。结果表明,麻织物经漆酶催化可实现溶菌酶的固定化,麻纤维木质素含量越高,溶菌酶接枝越多,整理后棉/亚麻织物和黄麻织物抑菌率分别达到60.38%和72.87%,且通过接枝法固定溶菌酶的麻织物较吸附固定法具有更好的耐水洗稳定性和抗菌效果。     

低温等离子体接枝改性聚丙烯中空纤维膜及其动电现象

采用丙烯酸和丙烯酰胺为单体,对聚丙烯中空纤维膜表面进行低温等离子体表面处理并引发接枝反应。红外拉曼光谱(FT-IR)分析结果表明,丙烯酸(AA)和丙烯酰胺(AM)分别接枝到膜表面。设计了中空纤维膜流动电位测定装置,测定膜表面的流动电位,根据Hel mholtz-Smoluehowski方程式计算了不同单体接枝情况下聚丙烯膜表面ζ电位以及电荷密度,以表征膜表面改性的程度。结果表明,接枝了丙烯酸和丙烯酰胺的膜表面ζ电位以及电荷密度分别为-16.39mV、11.8×10-6C/m2和-20.44 mV、14.7×10-6C/m2,膜表面的荷电性能改变能够改善膜的表面性能,尤其是对分离带负电的胶体溶液具有重要意义。     

基于电子束共辐照接枝制备中空纤维纳滤膜

以聚砜超滤膜为基体,采用电子束共辐照接枝2-丙烯酰胺基-2-甲基丙磺酸(AMPS)单体制备中空纤维纳滤膜。采用衰减全反射-傅里叶变换红外光谱分析接枝前后膜表面化学组成,并探讨接枝条件对纳滤膜接枝率、孔径以及脱盐性能的影响。结果表明,电子束能够穿透基膜,使膜内外表面均接枝上AMPS。以最佳接枝条件(辐照剂量80 k Gy,单体浓度10%,阻聚剂浓度1.5%,交联剂浓度0.2%,乙醇/水=1/9,溶液体积30 m L)制备的纳滤膜接枝率为4.68 mmol/m2,孔径为5.4 nm,0.4 MPa压力下对1 g/L Na2SO4的截留率为88.9%,渗透通量为28.3 L/(m2·h)。     

聚丙烯微孔膜表面接枝聚合丙烯酰胺的改性研究

用化学方法在聚丙烯微孔膜表面接枝丙烯酰胺单体,分别考察了反应温度、单体浓度、反应时间和引发剂浓度等反应因素对接枝率的影响,红外光谱和扫描电镜证实了丙烯酰胺在聚丙烯微孔膜表面的接枝,水接触角测试显示接枝膜具有良好的亲水性,热分析表明接枝膜基本没有改变聚丙烯微孔膜的基体性质.实验发现当反应温度为60℃,单体浓度为10%,反应时间为4h,引发剂浓度为2.0×10-3mol/L时,获得最佳接枝效果.     

生物酶催化UHMWPE纤维表面改性

以辣根过氧化物酶(HRP)为催化剂,在H₂O₂存在下,氧化邻甲氧基酚形成自由基,引发超高分子量聚乙烯纤维(UHMWPE)表面接枝聚丙烯酰胺,达到其表面改性的目的。通过正交实验确定了表面接枝的最佳条件:反应时间为1.5 h,H₂O₂的浓度为0.03%,邻甲氧基酚的浓度为0.5%。纤维单丝拔出实验结果表明,酶法改性的UHMWPE纤维/环氧树脂体系的界面粘结强度有明显提高,最大拔出强度比原纤维提高了69.8%。电镜扫描及红外光谱表征结果显示,改性后的UHMWPE纤维表面的粗糙度增加,并有新基团产生。      

紫外辐照改性聚丙烯纤维固定化溶菌酶的研究

在聚丙烯纤维紫外光照法接枝甲基丙烯酸甲酯(MMA)的基础上,通过酰胺化反应将改性纤维表面官能团转换为胺基后进行溶菌酶固定化,实现聚丙烯纤维的酶法功能化改性.通过对比不同处理条件下纤维的红外光谱(FT-IR)和扫描电镜(SEM),可以看出MMA已经成功接枝到聚丙烯纤维上,并且将溶菌酶固定在了纤维上.另外,还考察了MMA接枝率对纤维表面胺基密度和固定化溶菌酶酶活的影响.结果表明,纤维上的胺基密度随改性效果的提高而增大,当接枝率为1.69%时,固定化的溶菌酶酶活达到最大值为18U/cm2.     

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.