双醛低聚异麦芽糖交联脱细胞猪真皮基质的研究

采用新型交联剂氧化低聚异麦芽糖(IMODA)交联脱细胞猪真皮基质(pADM),优化最佳交联条件,考察了交联材料(IMODA-pADM)的收缩温度、改性指数、傅里叶红外光谱、机械性能、亲水性、吸湿性、表面形貌、耐酶解性能及细胞相容性。结果显示,交联材料的收缩温度随IMODA的用量、反应温度、反应时间的增加而先增大后趋于稳定,随pH值的增加而先增大后减小。交联最优条件为,反应温度37℃、用量16%、反应时间18h、pH值为9.4;随用量增大,交联材料改性指数增大,物理机械性能提高,亲水性与吸湿性略有降低,耐酶解性能大幅提高;交联后材料更为紧实,材料表面有利于细胞粘附生长,细胞形态良好,细胞毒性为0-Ⅰ级。     

异氰脲酸三缩水甘油酯改性脱细胞猪真皮基质的研究

采用异氰脲酸三缩水甘油酯(TGIC)对脱细胞猪真皮基质(p ADM)进行交联改性,考察了反应温度、p H值、用量和反应时间对基质材料收缩温度的影响,对交联前后基质材料的表面形貌、红外、热稳定性、耐酶降解性、力学性能、接触角等物理化学性能进行了表征,检测了基质材料的细胞毒性。结果表明,当反应温度为37℃,p H值为9.2左右,反应16~20 h,TGIC用量为10%时,基质材料的交联程度最大,收缩温度高达84℃;基质材料经TGIC交联能显著提高其形态稳定性、机械强度、热稳定性、耐酶降解性和亲水性,同时仍具有良好的细胞相容性,细胞毒性评级为Ⅰ级。     

丙三醇缩水甘油醚交联脱细胞猪真皮基质的亲水性研究

分别采用0.5%、10%、20%、40%、100%(质量比)丙三醇缩水甘油醚(GPE)交联脱细胞猪真皮基质(pADM),检测交联前后材料的亲水性能.研究结果表明,随着交联剂GPE用量的增加,材料的收缩温度逐渐提高,接触角明显降低;电镜扫描图显示交联后材料的孔隙有缩小的趋势,并导致了吸湿率和溶胀率的逐渐下降;红外图谱表明...     

单组分甲基改性硅溶胶的制备与性能分析

硅溶胶的硅氧键由于刚度太大而易在成膜交联过程中形成微裂纹。为了弥补这一缺陷,以硅烷偶联剂与硅溶胶为原料,通过溶胶-凝胶法制备出改性硅溶胶溶液,并将其涂在铝板表面;研究了硅溶胶的pH值、 pH值调节剂种类、反应时间对改性硅溶胶产物及其涂层性能的影响,采用傅里叶红外光谱仪、热重分析仪和接触角测定仪等对涂层性能进行了表征。结果表明：改性后的硅溶胶性能稳定,其涂层表面光滑,铅笔硬度达到6 H,耐温500℃,接触角约为91°,热稳定性良好。     

罗非鱼鳞胶原蛋白膜抗水性和机械性能研究

以戊二醛作为交联剂对罗非鱼磷胶原蛋白交联改性。研究交联剂对罗非鱼鳞胶原蛋白膜抗水性能和机械性能的影响。通过检测改性后胶原膜的拉伸强度、断裂伸长率、抗水性、吸水率、水接触角等指标来对胶原膜进行表征。结果表明,对胶原膜机械性能影响因素依次为pH值温度戊二醛量;对胶原膜抗水性影响因素依次为戊二醛量pH值温度;当戊二醛的添加量为8%,pH值为2.9,加热温度为40℃时,胶原蛋白膜的机械、抗水综合性能最优,抗拉伸强度为31.32 MPa,断裂伸长率为65.24%,抗水性为34.85%,水接触角为120.24°。     

交联羧甲基玉米淀粉／PVA复合膜制备工艺的研究

以玉米淀粉为原料,采用先醚化后交联改性工艺合成了交联羧甲基玉米淀粉(CCMS).通过改性淀粉与聚乙烯醇(PVA)溶液共混反应,并辅以增塑剂、增强荆、交联剂及疏水化改性剂等加工助荆制备了性能优异的CCMS/PvA复合膜.研究了复合膜制备过程中的影响因素及其对薄膜耐水性能、透光性能和力学性能的影响.结果表明,当交联羧甲基玉米淀粉与PVA的质量比为7:3,甘油用量为10%(质量分数),复合交联剂用量3.3%(质量分数),疏水化改性荆聚酰胺多胺环氧氯丙烷树脂(PPE)用量为1.5%(质量分数),溶液pH为10,反应温度88℃,反应时间35min时,淀粉膜的拉伸强度为40.5MPa,断裂伸长率为311%,透光率为82%,吸水率最小为3.6%(质量分数).     

新型包埋微生物材料-室温交联聚丙烯酰胺的合成

首先合成低分子量的聚丙烯酰胺，再用甲醛使其羟甲基化，最后羟甲基化聚丙烯酰胺和丙烯酰胺缩合得到可室温交联的聚丙烯酰胺。研究了反应物摩尔比、反应温度、反应时间和溶液pH值等因素对羟甲基化和缩舍反应的影响，确定了最佳反应条件。这种改性聚丙烯酰胺的水溶液和交联剂于室温可快速交联得到凝胶体。该工艺的优点是对微生物细胞无毒性，聚合（包埋）温度低，交联发生在侧链使抗水解性增强。     

胶原-壳聚糖二元膜材料的制备与性能表征

通过热脱氢交联（DHT）、戊二醛改性以及碳化二亚胺改性（EDC）等方法对胶原基膜材料进行改性，探讨其作为生物医用材料较为理想的改性方法。以胶原及壳聚糖为主要原料制备大孔径高孔率二元膜材料，通过单一或复合改性以后比较二元膜材料的各项性能。适当的DHT改性后获得的二元膜孔径为20～100μm，孔率90％左右，但膜材料机械性能较差，抗酶解能力提高不明显；0．02％的戊二醛．EDC复合改性交联程度较为合适，DHT改性可以一定程度减少戊二醛用量；DHT-EDC复合改性得到的二元膜孔径20～200μm，孔率95％左右，机械强度和耐酶稳定性较高，吸水率高且在水中不溶胀。DHT-EDC复合改性是较为理想的胶原基膜材料作为生物医用材料的改性方法。     

环氧化合物和碳化二亚胺交联pADM的性能比较

采用丙三醇缩水甘油醚(GPE)和碳化二亚胺(EDC)对脱细胞真皮基质(pADM)分别进行交联改性,通过对交联后材料EC(GPE)-pADM、EDC-pADM的交联效率、XPS分析、KM鼠经口急毒、浸提液细胞毒性的表征和比较,探寻改性方法与材料性能之间的基本关系.研究结果表明,EDC比EC具有更高的交联效率;EC-pADM的亲水性能比EDC-pADM更好;EDC-pADM漫提液对KM鼠表现出一定经口毒性,而EC-pADM的毒性相对较低;两者浸出液细胞毒性检测均合格.综合而言,EC-pADM的性能优于EDC-pADM.     

胶原/TiO2纳米复合红外低发射率材料的制备与表征

用胶原与改性纳米TiO2复合得到新型有机-无机复合材料，研究复合物中胶原的含量随复合温度、pH的变化规律，并考察TiO2晶型、Al2O3包膜改性及戊二醛交联改性对复合材料红外发射率的影响．结果表明;胶原与改性纳米TiO2复合的最佳温度为50℃、pH为8．0，胶原含量最高可达9．45wt％，两者间较强的复合协同作用明显降低了材料的红外发射率，并提高了材料的热稳定性；复合材料经戊二醛交联改性后可形成紧密有序的网络层状结构，热稳定性进一步提高，红外发射率最低可降至0．502．     

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.     

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.……     

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.     

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.     

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.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

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.