NaA分子筛改性聚砜超滤膜的通量及截留性能

利用溶液相转化法,在铸膜液中加入分子筛NaA和PEG来协同提高聚砜超滤膜的水通量和截留率,研究了分子筛的含量对聚砜超滤膜的形貌结构,表面粗糙度,水通量,蛋白质截留率和亲水性的影响。利用场发射扫描电镜、扫描探针原子力显微镜、膜评价仪和接触角仪分别对该膜的形貌、水通量、蛋白质截留率和亲水性进行表征。结果表明分子筛含量从0g增加到3.0g,聚砜超滤膜的水通量从140L/(m2·h)提高到500L/(m2·h),对胃蛋白酶的截留率从78.8%提高到92.7%,对牛血清蛋白的截留率从97.6%增加到99.0%以上。分子筛NaA可以协同提高聚砜超滤膜的水通量和蛋白质截留率。     

改性聚偏氟乙烯超滤膜的制备与性能的研究

以接枝马来酸酐的改性聚偏氟乙烯(PVDF-g-MAH)为膜材料,采用浸没沉淀相转化方法制备超滤膜.在绘制PVDF-g-MAH-溶剂-水体系的三元相图基础上,研究并讨论铸膜液中溶剂体系、聚合物浓度以及添加剂浓度配比对膜性能和结构的影响,比较了接枝前后超滤膜的亲水性和抗污染性.研究结果表明:在聚合物-溶剂二元体系发生相分离过程中,4种溶剂体系所需非溶剂(水)的量的顺序为:DMAC>NMP>DMF>DMSO;以DMAC溶剂制备的铸膜液,制得的膜表面相对致密,纯水通量小,截留率高;随着聚合物浓度的提高,膜的通量下降,截留率提高;同时SEM照片也显示了随聚合物浓度的增加,超滤膜表层趋于致密,支撑层指状孔孔径缩小,孔数增多;超滤试验结果表明,在截留率相同的前提下,用PVDF制备的超滤膜纯水通量为104.6 L/(m2·h),而PVDF-g-MAH制得的超滤膜纯水通量为230L/(m2·h),同时对比了连续超滤BSA溶液12 h后的膜通量衰减状况,两种膜的通量的衰减率分别为36%和15.4%,表明以改性材料制备的超滤膜的亲水性和抗污染性能均得到提高.     

臭氧接枝制备亲水性聚偏氟乙烯中空纤维油水分离膜

膜分离法是一种高效低耗的含油污水处理方法。用于油水分离的膜材料要求既具有良好的亲水性又具有良好的成膜性和力学性能,因此需要对膜进行改性。文中首先在聚偏氟乙烯分子链上臭氧接枝丙烯酸,然后再利用干湿法纺丝制备中空纤维膜,并研究了制膜条件对膜的油水分离性能的影响。实验结果表明,改性后的膜亲水性较好(水接触角50°),具有很高的纯水通量(400L·m-2·h-1以上)和较高的煤油截留率(95%)。同时,研究结果表明提高铸膜液浓度、提高挤出压力以及在凝固浴中添加溶剂会使膜的水通量下降而截留率上升。     

乳状液膜法脱酚的进一步研究

对模拟的含酚废水,采用乳状液膜法脱酚进行了进一步的探讨．实验研究了对所采用的制乳设备——撞击流-旋转填料床对制乳率,提取设备——旋转填料床对脱酚率和破乳设备——无机微孔膜外压内抽式膜法破乳的重要参数如透过压方式、膜孔径等对膜通量和破乳率的影响．并且讨论了破乳后的油相回用情况．实验结果表明:撞击流-旋转填料床对制乳率、脱酚率都很高,且瞬间完成．亲水性无机微孔膜外压内抽方式破乳,是一种更有效的膜法破乳新方法,此过程受透过压方式和膜孔径的影响较大．膜孔径越小,破乳率越高,膜通量越小;外压内抽方式的破乳效果优于单外压方式的破乳效果．并由实验数据得到:撞击流-旋转填料床的制乳效率可达99．90％以上,脱酚率可达99％左右,对于粒径为5-25μm乳液,用膜孔径为2．0μm的SiC微孔膜,在外压为60 kPa、内负压为30 kPa的外压内抽破乳方式下破乳,破乳率可达96．4％,膜通量可达900 L／(m2·h)．     

陶瓷超滤膜在右旋糖酐分离中的应用

本文采用自制的陶瓷超滤膜分离右旋糖酐,研究了操作参数如压力、温度、膜面流速和料液浓度等对陶瓷超滤膜分离右旋糖酐的影响,并对操作参数进行了优化.所用陶瓷超滤膜材料为氧化锆,切割分子量约为2 700,纯水渗透率约为375L/(m~2·h·MPa).研究表明,增大操作压力,膜通量以及右旋糖酐的截留率均有所增加.当操作压力增加至0.3 MPa时,右旋糖酐与果糖的分离因子最大,二者的分离效果最好.温度变化时,膜通量随温度的升高而升高,但右旋糖酐的截留率随温度的上升而下降.适当增大膜面流速有利于增大膜通量和右旋糖酐的截留率.此外,还考察了陶瓷超滤膜在右旋糖酐分离纯化过程中的稳定性.当料液浓度为60g/L时,陶瓷膜在连续12h的运行过程中,膜通量稳定在24L/(m~2·h)左右,分离因子稳定在11.5以上.陶瓷超滤膜在右旋糖酐分离方面展现了良好的应用前景.     

Al2O3/TiO2/PVDF杂化超滤膜的制备及其性能研究

为提高聚偏氟乙烯(PVDF)超滤膜的亲水性,增强其在水处理中的抗污染能力,用无机纳米二氧化钛(TiO2)、氧化铝(Al2O3)与聚偏氟乙烯共混,采用相转化法制得无机改性有机高分子杂化超滤膜。采用杯式超滤装置考察了无机纳米颗粒的含量对杂化膜水通量的影响;测定了膜的纯水接触角、机械性能、截留效率和膜的孔径及孔径分布;采用扫描电子显微镜对膜表面进行观察。结果表明,纳米颗粒加入量为3%,TiO2与Al2O3的加入比为1∶1时,杂化膜的水通量较有机膜提高了79.5%,但截留率保持不变;杂化膜的机械强度最大增加41.6%;杂化膜的纯水接触角由未改性前的78.68°降至50.54°,亲水性得到明显改善;杂化膜的平均孔径增大,孔径分布更加均匀;纳米颗粒的加入增加了膜表面的孔密度,但没有改变膜断面的微观结构。杂化超滤膜不仅保持了PVDF膜的优良性能,而且增强了其强度、亲水性和抗污染性能。     

有机溶剂对聚砜管式超滤膜性能的影响研究

采用不同种类的有机溶剂对聚砜管式超滤膜进行处理,并考察了其对膜性能及结构的影响.结果表明,用烷烃处理过的膜表面变光滑,碳元素含量增加,膜表面亲水性下降,水通量降低,对硫酸镁和卵清蛋白的截留率升高;用醇处理过的膜表面变粗糙,碳、氧元素含量增加,膜表面亲水性提高,膜水通量增加,对卵清蛋白截留率略有降低.     

气态法进行聚砜中空纤维超滤膜表面紫外光引发接枝聚合改性的实验研究

利用聚砜中空纤维膜内表面作为接枝层,进行动态表面光接枝聚合反应的研究——在气态条件下进行引发并在液态条件下进行接枝反应．实验结果表明：用二苯甲酮作为引发剂,丙烯酰胺作为亲水性接枝单体,聚丙烯酰胺链可以被接枝到膜表面．通过对反应前后的接触角、水通量和截留率的测量,发现分离膜的亲水性和孔径都发生了变化,而且接枝聚合的程度随着参数和实验条件的变化而变化,如引发时间、单体浓度、聚合温度和聚合时间等．此方法对于制造较小孔径的中空纤维超滤膜提供了新思路,是非常值得发展和研究的方向．     

磺化聚砜在聚醚砜膜亲水改性中的制备与表征

以聚醚砜(PES)和磺化聚砜(SPSf)为膜材料,N,N-二甲基乙酰胺(DMAc)为溶剂,聚乙二醇(PEG)为制孔剂,采用干湿法制备中空纤维超滤膜,研究了不同磺化度的SPSf及SPSf浓度对中空纤维共混膜的影响,通过傅里叶变换红外光谱仪、扫描电镜和孔径测试,分别研究了SPSf的化学结构、膜的形态和孔径分布。通过超滤膜性能的测试,探讨了共混膜性能的影响。结果表明,在磺化度10%,磺化聚砜质量分数4%时,超滤膜的水通量为450 L/(m2·h),对聚乙二醇-20000(PEG-20000)的截留率为95%;共混膜随温度的升高,共混膜的水通量降低,截留率几乎稳定不变;对牛血清蛋白(BSA)的通量衰减率为10.9%,通量恢复率为21%。     

活性炭填充对聚砜超滤膜性能的影响

采用相转化法制备聚砜(PSF)超滤膜,通过正交实验确定了较优的制膜条件,并用活性炭填充制备了共混的聚砜超滤膜,考察了活性炭加入量对膜的水通量、牛血清白蛋白(BSA)截留率及孔隙率的影响,以及操作条件对填充膜性能的影响。结果表明,最优化制膜条件为:添加剂聚乙二醇(PEG-400)含量为8%,蒸发时间为60s,纯水作为凝固浴,在此条件下制得的膜水通量达到212.6L/(m2.h),BSA截留率为84.1%。活性炭填充对膜水通量和截留率有明显影响,在活性炭含量为0.5%～1.5%时,膜通量随操作压力增大而增大,而截留率变化不大。     

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.……     

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.     

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...     

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 ...