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．     

碳化二亚胺改性胶原纤维支架材料的特性表征

用碳化二亚胺(EDC)对胶原纤维支架材料(CFSM)进行改性,评价了改性前后的胶原纤维支架材料的理化及生物降解性能.结果表明:胶原的羧基与EDC的氨基发生了酰胺化反应,且EDC改性未破坏胶原的三股螺旋结构.随着EDC用量增加,EDC-CFSM的热变性温度升高明显,耐降解性显著提高.用浓度为14mmol/L的EDC改性得到的EDC-CFSM表现出较优的生物学性能,其热变性温度达96.7℃,耐降解性最优,孔隙率为80.91%,孔径约为70～180μm.     

多孔胶原-β-磷酸三钙-硫酸软骨素复合膜的制备与表征

通过碳化二亚胺(EDC)改性、二次冻干制备多孔胶原-β-磷酸三钙-硫酸软骨素复合膜材料.通过扫描电镜(SEM)、X射线衍射分析仪(XRD)与原子力显微镜(AFM)考察了组分变化与制备过程中复合材料的微观形貌变化,并进一步利用红外、孔隙率、MTT细胞毒性实验等分析手段对复合材料的结构与性能进行了表征.实验结果表明,当胶原盐酸溶解液pH=2,胶原与β-磷酸三钙质量比为1∶2(m(Col)∶m(β-TCP)=1∶2)时,复合材料中β-TCP晶相保持较好,其与胶原之间的排列结合最为均匀紧密.经EDC改性后,SEM与AFM实验均显示了交联后的胶原束明显变大变粗,以一定的方向紧密地排列在一起.XRD图谱显示复合材料中β-TCP特征衍射峰明显.复合材料的孔径为80～90 μm,三元膜孔隙率为(90.76士1.28)％,大于纯胶原冻干膜(85.88士0.92)％;红外光谱证实β-TCP中的钙离子与Col上的羧基发生了化学键合,AFM显示β-TCP颗粒能与胶原发生直接联结.复合材料的MTT实验结果为1级,是一种潜在的口腔修复膜材料.     

多孔胶原-β-磷酸三钙-硫酸软骨素复合膜的制备与表征

通过碳化二亚胺(EDC)改性、二次冻干制备多孔胶原-β-磷酸三钙-硫酸软骨素复合膜材料。通过扫描电镜(SEM)、X射线衍射分析仪(XRD)与原子力显微镜(AFM)考察了组分变化与制备过程中复合材料的微观形貌变化,并进一步利用红外、孔隙率、MTT细胞毒性实验等分析手段对复合材料的结构与性能进行了表征。实验结果表明,当胶原盐酸溶解液pH=2,胶原与β-磷酸三钙质量比为1∶2(m(Col)∶m(β-TCP)=1∶2)时,复合材料中β-TCP晶相保持较好,其与胶原之间的排列结合最为均匀紧密。经EDC改性后,SEM与AFM实验均显示了交联后的胶原束明显变大变粗,以一定的方向紧密地排列在一起。XRD图谱显示复合材料中β-TCP特征衍射峰明显。复合材料的孔径为80~90μm,三元膜孔隙率为(90.76±1.28)%,大于纯胶原冻干膜(85.88±0.92)%;红外光谱证实β-TCP中的钙离子与Col上的羧基发生了化学键合,AFM显示β-TCP颗粒能与胶原发生直接联结。复合材料的MTT实验结果为1级,是一种潜在的口腔修复膜材料。     

胶原基复合止血材料的研究进展及展望

胶原蛋白可用于多种止血场景，并凭借优越的性能和易于获取的特点逐渐取代传统止血材料。然而，不同剂型的胶原止血剂都存在各自的缺陷，如力学性能差、粘附性差等。虽然提纯或交联改性胶原能在一定程度上获得改善，但作用有限，临床应用仍深受限制。天然生物及其衍生物材料是来源丰富的止血剂，具有生物相容性和良好的吸收和降解性能。广泛使用的材料包括壳聚糖、纤维蛋白胶、藻酸盐和氧化纤维素，以及近年来逐渐受到重视的传统中药材。因此，胶原蛋白与天然生物及其衍生物材料交联而成的胶原蛋白基复合止血材料，有望成为极具前景的生物医用止血材料。本文综述了不同类型胶原基复合止血材料的研究进展，总结了各自的优缺点，最后对胶原基复合止血材料的未来发展方向进行了探讨。     

醛与胶原反应的研究

本文采用甲醛、乙二醛和戊二醛分别对酶解法提取的Ⅰ型胶原进行了化学修饰，研究了这几种修饰剂的pH值和浓度对修饰效果的影响。探讨了醛修饰胶原的机理并确定最佳工艺参数分别为：甲醛pH=9，浓度4％；乙二醛pH=9，浓度3％；戊二醛pH=6，浓度2％，三者所需浓度大小依次为甲醛〉乙二醛〉戊二醛。     

医用牙周组织引导再生胶原材料的特性

用酶消化法从牛腱中提取出胶原蛋白，采用涂复法制成胶原膜材料，将该膜用０．２５％的甲醛交联后得到用于牙周组织引导再生的材料．在对胶原材料进行物理、化学性能测试后表明：该材料的力学性能超过国外同类制品并具有较好的吸水性，而且胶原材料的羰基、羧基、羟基和胺基等主要结构基团依然存在经体外胶原酶和体内肌肉包埋降解吸收观察，材料在体外约２４０小时降解完全，降解产物为羟脯氨酸，体内吸收时间为６０天左右．对该材料进行生物学评价后证明：该材料无三致反应和其它毒副作用，无热原和过敏反应及溶血现象等，生物相容性优良．因此，该材料可用于牙周组织引导再生术及更广泛的生物隔膜技术中．     

基膜改性的壳聚糖／聚丙烯腈渗透气化中空纤维复合膜

采用粒子填充的聚丙烯腈（PAN）作为基膜材料，纺制成了中空纤维，对基膜进行拉伸，热定型等后处理，并在此基础上研制了壳聚／聚丙烯腈中空纤维复合膜，考察了基膜的改性及不同操作条件对复合膜分离性能的影响，发现采用该基膜制备的复合膜对乙醇－水体系具有很好的分离性能。     

多巴胺的自聚-附着行为与膜表面功能化

多巴胺(dopamine)是一种生物神经递质,在水溶液条件下,它能在溶解氧的作用下发生氧化-交联反应,形成强力附着于固体材料表面的聚多巴胺复合薄层.基于多巴胺的这一特性,近年来膜技术研究者们通过多巴胺在固体基膜上的自聚-复合,对膜进行表面改性,并以具有反应活性的聚多巴胺复合层为平台,对膜进行进一步的表面修饰,实现膜的功...     

以核孔膜为基底疏/亲水复合膜的制备及其DCMD性能研究

创新性地将核孔膜作为基膜,使用聚偏氟乙烯(PVDF)为膜材料,N,N-二甲基乙酰胺(DMAc)为溶剂,采用非溶剂致相分离法制备了PVDF/PET核孔膜复合疏水/亲水膜,并对复合膜的微观结构、机械性能、亲疏水性、孔隙结构进行深入表征,研究了添加剂含量和核孔膜孔径对膜微观形态和性能的影响.结果表明,提高LiCl添加剂含量使得铸膜液的黏度增大,膜指状孔结构变小且海绵状结构变紧密,PVDF/PET核孔复合膜的平均剥离力从4.48 N下降为1.19 N,孔径从0.132 7μm减少到0.080 4μm,孔隙率从44.65%减少至37.60%;核孔膜孔径增大导致复合膜的机械强度下降.直接接触式膜蒸馏(DCMD)分离性能测试表明,PVDF/PET核孔复合膜通量比相同厚度单层PVDF疏水膜通量提升约30%;可稳定运行超过39 h.     

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.……     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

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.     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

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.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...