石墨烯负载小尺寸氧化锌纳米颗粒及其光催化性能研究

利用共沉淀法实现石墨烯纳米片均匀负载粒径为5nm的氧化锌颗粒,并研究了石墨烯／氧化锌纳米衍生体的光催化性能,结果表明,合成的石墨烯／氧化锌纳米衍生体比纯氧化锌纳米颗粒对甲基橙有机染料具有更好的光催化活性。当石墨烯在衍生体中的含量为0．51wt．％时,获得的衍生体具有最强的光催化活性,在90rain内能全部降解溶液中的甲基橙。光催化活性的提高主要贡献于石墨烯良好的电子输运性能,能有效阻止氧化锌纳米颗粒中光生电子和空穴对之间的复合。     

复合纳米ZnO-SnO2粉体的电合成及光催化性能的研究

采用改进的电化学法制备了ZnO-SnO2纳米复合氧化物粉体,通过XRD、FT-IR、TEM等测试手段,对产物的物相组成、粒径大小、形貌等进行了表征;并考察了该纳米复合粉体的光催化活性.结果表明,得到的产物(氧化锌与氧化锡的复合物)颗粒分布均匀、平均粒径约为30～50 nm;该复合氧化物对甲基橙及亚甲基蓝溶液的光催化降解明显优于单纯的ZnO或SnO2;前驱体的焙烧温度以及ZnO和SnO2的复合摩尔比对ZnO-SnO2的光催化活性有较大的影响.     

热还原法制备氧化石墨烯/TiO_2复合材料及其光催化性能研究

采用Hummers法制得氧化石墨烯,以钛酸丁酯为钛源,采用原位溶胶-凝胶技术制备了氧化石墨烯/TiO2复合材料,进一步经过加热还原的方法,制备热还原氧化石墨烯/TiO2复合光催化剂,通过FT-IR、XRD、Raman、SEM、TEM和UV-Vis光谱等对产物进行了表征,并测试了该复合光催化剂在可见光下对甲基橙的光催化降解性能。结果表明,制备的复合光催化剂主晶相为锐钛矿型TiO2,热还原氧化石墨烯表面富集的颗粒尺寸15nm左右,颗粒分布均匀。热还原氧化石墨烯/TiO2复合光催化剂在可见光下具有优异的光催化性能。     

壳聚糖/Ni-TiO2复合絮凝剂对印染废水的处理研究

利用溶胶-凝胶法制备壳聚糖/Ni-TiO2复合絮凝剂,去处理模拟印染废水。用可见分光光度测定法对甲基橙的含量进行了测定,考察了壳聚糖/Ni-TiO2复合絮凝剂投加量、反应时间、反应温度、pH值对废水处理效果的影响。结果表明:在超声波频率为50kHz时,甲基橙溶液初始浓度为25mg/L,溶液pH=6,壳聚糖/Ni-TiO2复合絮凝剂的加入量为0.1g,时间60min,温度为40℃,甲基橙溶液脱色率到达到95.0%以上。同时,壳聚糖/Ni-TiO2复合絮凝剂处理甲基橙溶液时,不仅有吸附作用的存在,同时还有光催化降解的作用。     

PMMA/TiO2复合粒子光催化降解有机污染物的性能

采用原位乳液聚合的方法制备PMM A/T iO2复合粒子。以甲基橙溶液、甲醛溶液、苯酚溶液为目标降解物,通过测试甲基橙溶液光催化反应前后紫外-可见吸收光谱的变化以及气相色谱测试甲醛、苯酚光催化反应后产生CO2的百分含量,研究了T iO2粒子和PMM A/T iO2复合粒子光催化降解有机污染物的性能。结果表明,PMM A/T iO2复合粒子光催化降解甲基橙、甲醛和苯酚的性能略优于T iO2。对经过紫外光照射以后的PMM A/T iO2复合粒子进行红外光谱及热失重测试,结果表明,PMM A/T iO2复合粒子的红外光谱在紫外光照射后没有变化,热失重曲线显示PMM A/T iO2复合粒子紫外光照射前后的热分解温度和失重率接近,这说明紫外光照射后,复合粒子中的PMM A并未被T iO2降解,具有很好的光稳定性。     

热处理温度对TiO2/SiO2复合气凝胶光催化性能的影响

采用溶胶–凝胶法在常压下经不同温度热处理制备了TiO2/SiO2复合气凝胶光催化剂,利用XRD、TGA和BET等手段对其微观结构进行表征,以甲基橙溶液光催化降解实验评价其光催化性能,研究了热处理温度对TiO2/SiO2复合气凝胶的微观结构及光催化性能影响规律.结果表明:随着热处理温度升高,TiO2/SiO2复合气凝胶中锐钛矿结晶度升高,晶粒尺寸增大,比表面积减小,使TiO2/SiO2复合气凝胶对甲基橙溶液的光催化降解活性呈现先升后降的变化趋势.当热处理温度为700℃左右,紫外光照20 min TiO2/SiO2复合气凝胶对甲基橙溶液的降解率达到95.4%.     

Si含量对TiO_2/SiO_2复合气凝胶结构及光催化性能的影响

采用溶胶-凝胶法制备了不同Si含量的TiO2/SiO2复合气凝胶.利用XRD、FTIR、XPS和BET等手段表征了复合气凝胶组织结构,以甲基橙溶液光催化降解实验评价其光催化活性,研究了Si含量对TiO2/SiO2复合气凝胶的结构及光催化性能影响规律.结果表明:TiO2/SiO2复合气凝胶中Ti-O-Ti、Si-O-Si和Ti-O-Si键相互交织,使复合气凝胶具有小晶粒尺寸、高比表面积和高热稳定性.随着Si含量增大,TiO2/SiO2复合气凝胶中TiO2晶粒尺寸减小,TiO2结晶度降低,比表面积增大,平均孔径减小,且TiO2/SiO2复合气凝胶对甲基橙溶液的光催化降解活性呈现先升后降的变化趋势.适当Si含量能显著改善TiO2/SiO2复合气凝胶的结构和光催化性能,Si含量最佳值在9wt%附近.     

生物模板法合成多孔结构氧化铈及其吸附性能研究

以壳聚糖为生物模板制备介孔纳米氧化铈材料,对合成的纳米氧化铈进行了X射线衍射(XRD),扫描电子显微镜(SEM),N_2-吸附脱附表征。以甲基橙溶液为模拟的染料废水,探究了氧化铈的用量、溶液的pH、吸附时间等因素,对介孔氧化铈吸附甲基橙溶液的影响。结果表明:合成的纳米氧化铈具有海绵状多孔的微观结构,比表面积为202m~2/g,空隙量为0.199cm~3/g,平均孔径为12.48nm,在pH=7,纳米氧化铈用量为0.3g,甲基橙浓度为3mg/L,吸附时间为30min的条件下,对甲基橙的吸附率可达到61.56%。     

壳聚糖-CdS复合纳米粒子对甲基橙的光催化降解作用

用反相微乳液法制备了壳聚糖-CdS复合纳米粒子,并考察了复合纳米粒子用量、光照条件和溶液pH值等因素对光催化降解甲基橙的影响.结果表明:在100 mL质量浓度为20 mg/L的甲基橙溶液中加入0.30 g复合纳米粒子,可以达到较好的光催化降解效果;甲基橙在光催化降解过程中最大吸收波长464 nm处的吸收峰迅速减弱,并最终消失,且在258 nm和455 nm处出现了新的吸收峰,说明甲基橙发生了降解;溶液pH值对光催化降解甲基橙有一定的影响,在弱酸性条件下降解效率较高;复合纳米粒子比普通CdS降解效率高,2 min时高出50%,400 min时高出21.3%.初步提出了复合纳米粒子光催化降解机理,复合纳米粒子的吸附作用是光催化降解作用的前置步骤.     

石墨烯/Ni/TiO_2/CNTs复合物的制备及其光催化性能

首先通过溶剂热法,在石墨烯表面负载掺杂镍的纳米二氧化钛膜,制备石墨烯/Ni/TiO2复合材料;然后以掺杂的镍为催化剂,采用化学气相沉积法,原位生长碳纳米管(CNTs),得到石墨烯/Ni/TiO2/CNTs复合材料。通过XRD、SEM、TEM、拉曼等方法对制备样品的晶型、微观形貌等进行了表征,考察了样品在紫外光及可见光下对甲基橙的光催化降解性能。结果表明:石墨烯和CNTs的加入使得Ni/TiO2、石墨烯/Ni/TiO2、石墨烯/Ni/TiO2/CNTs复合物的光催化活性依次提高,并且石墨烯/Ni/TiO2/CNTs复合物中石墨烯含量越多时,所得复合物的光催化降解性能越好。石墨烯含量最大的石墨烯/Ni/TiO2/CNTs样品,在紫外光下对甲基橙的降解率达到98%,在可见光下的光催化降解效率比掺镍TiO2提高了3.5倍。     

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 ...