PPy/MWNTs/GO复合材料的制备与电化学性能研究

以吡咯为单体,多壁碳纳米管和氧化石墨烯为模板,过硫酸铵为氧化剂,采用原位化学聚合法制备了聚吡咯/多壁碳纳米管/氧化石墨烯(PPy/MWNTs/GO)复合材料.利用傅里叶变换红外光谱(FTIR)、X射线衍射谱(XRD)、扫描电镜(SEM)、循环伏安法(CV)和电化学交流阻抗谱(EIS)对制备复合材料的结构、微观形貌和电化学性能进行了研究,探讨了多壁碳纳米管/氧化石墨烯比例、吡咯用量对复合材料电容性能的影响.研究结果显示,PPy/MWNTs/GO复合材料具有较大的比电容和良好的循环稳定性,且具有较小的电荷转移电阻,接近于理想的超级电容器用电极材料.     

低温剥离法制备高性能石墨烯/ZnO复合材料

采用氧化石墨和七水合硫酸锌作为初始反应物, 在低温下(80℃)合成了氧化石墨/ZnO, 然后通过低温剥离法制备了高质量石墨烯/ZnO (GNS/ZnO)复合材料. 采用X射线衍射(XRD)、傅里叶变换红外(FTIR)光谱、热重分析仪(TG)、X射线光电子能谱(XPS)、拉曼光谱(RS)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)等分析手段对石墨烯/ZnO样品进行了表征. 结果表明: 氧化石墨还原彻底, 纳米ZnO成功地负载到了石墨烯上, 有效地减少了石墨烯片层间的团聚现象. 通过对ZnO和石墨烯/ZnO荧光性能测试, 结果表明: 石墨烯/ZnO发生了荧光淬灭现象, 在光电子领域拥有广阔的应用前景.     

红外光谱法氧化石墨烯羧基官能团含量的测定

建立一种红外光谱法测定氧化石墨烯中羧基对应氧化度的方法。利用改进Hummers法制备氧化石墨烯(GO),基于苯甲酸具有类似结构的原理,采用苯甲酸作为标准物质,苯甲酸傅里叶红外光谱在1 591,1504,1 423 cm-13处为苯环骨架伸缩振动特征吸收峰,在1 692 cm-1处为羧基中C=O的伸缩振动特征吸收峰,而GO的傅里叶红外光谱在1 630 cm-1为类苯环架构C=C的伸缩振动,在1 730 cm-1为羧基中C=O的伸缩振动特征吸收峰,这样,可利用苯甲酸上苯环和羧基中C=O的峰面积比值与GO上C=C和羧基中C=O的峰面积比值,通过结构分析和相关公式的计算,得到氧化度的值。并且利用紫外可见光谱,X衍射光谱,拉曼光谱,以及原子力显微镜对其进行对比验证,证明红外光谱的方法可行。可为氧化石墨烯羧基氧化度的测定提供一种操作简单、行之有效的方法。     

超声辅助镍粉绿色还原制备石墨烯

提出一种室温下利用镍粉还原氧化石墨制备石墨烯的新方法。采用X射线衍射(XRD)、傅里叶红外光谱(FTIR)、拉曼光谱(Raman)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)对氧化石墨还原后的产物进行表征。结果表明:氧化石墨中含氧基团基本被去除,生成的石墨烯的ID/IG达到了1.34,当镍与氧化石墨质量比值为2时,还原效果较为理想。这种方法为低成本、高效、环保、大规模地制备高品质石墨烯提供可能性。     

原料尺寸对氧化石墨与石墨烯性能的影响

采用改进的Hummers法对不同尺寸的天然石墨进行氧化处理,水合肼还原获得石墨烯。利用红外光谱(FTIR)、拉曼光谱(Raman)、X射线衍射(XRD)等对天然石墨、氧化石墨和石墨烯的化学结构、光谱学及结晶性进行表征。结果表明:天然石墨被充分氧化为氧化石墨,氧化石墨被还原为完美的石墨烯;天然石墨尺寸越小,氧化程度越大,氧化石墨的层间距越大;氧化石墨的D峰和G峰的强度比ID/IG与天然石墨尺寸大小成正比;与同尺寸的氧化石墨相比,石墨烯的ID/IG值比氧化石墨的大,说明石墨烯中sp2杂化碳层平面的平均尺寸小于氧化石墨的平均尺寸,新生成的石墨化区域被一些缺陷分割成尺寸更小的sp2杂化区域。     

聚乳酸/纳米羟基磷灰石/氧化石墨烯纳米复合膜的制备及生物性能研究

采用溶液浇铸法和超声分散工艺制备了聚乳酸/纳米羟基磷灰石/氧化石墨烯(PLA/n-HA/GO)纳米生物复合膜,利用扫描电镜(SEM)对其断面形貌进行了研究,借助X射线衍射(XRD)和傅里叶变换红外光谱(FTIR)分析了纳米羟基磷灰石和氧化石墨烯的加入对所得复合膜结构的影响,并对其生物相容性进行了探讨.结果表明,氧化石墨烯和纳米羟基磷灰石在复合膜中分散均匀;细胞在复合膜上贴附牢固、铺展良好,具有良好的生长形态.聚乳酸/纳米羟基磷灰石/氧化石墨烯复合材料为细胞提供了接近天然细胞外基质的人造微环境,显示了该材料在引导组织修复和再生领域中的应用潜力.     

高温还原GO制备LiFePO_4/石墨烯复合正极材料及表征

通过对氧化石墨烯(GO)进行微观调控处理得到少层GO。采用喷雾干燥再高温改性的方法制备LiFePO_4/石墨烯锂离子电池复合正极材料;GO还原后即可得到石墨烯,其优良的导电性可以提高LiFePO_4的电子传输能力。通过X射线衍射(XRD)、红外光谱(FTIR)、扫描电镜(SEM)、透射电镜(TEM)和电化学测试技术等方法对复合材料的结构、形貌及电化学性能进行表征。石墨烯的复合使材料颗粒间构建空间三维导电网络,提高了电解质/电极材料界面的电荷转移速率,改善了LiFePO_4的电化学性能。电化学测试结果表明,在0.1C时LiFePO_4的放电比容量为155mAh/g,LiFePO_4/石墨烯复合材料的放电比容量为164mAh/g;1C和2C倍率时,LiFePO_4/石墨烯复合材料的放电比容量分别为140,119mAh/g。     

利用维生素C和茶多酚还原氧化石墨烯及其表征

采用改进的Hummers法制备氧化石墨烯(Graphene oxide,GO),以环境友好和具有较强还原能力的茶多酚和维生素C为还原剂还原GO制备还原氧化石墨烯(Reduced graphene oxide,RGO).傅里叶变换红外光谱(FT-IR)测得还原后的RGO的含氧官能团吸收峰明显降低,在X射线衍射图谱(XRD)中观察到还原后的RGO的吸收峰位置的变化,原子力显微镜(AFM)观察到样品的厚度.这些表征数据表明实验采用的两种还原剂成功还原了GO制备出RGO.     

PAM/AMPS/GO纳米复合水凝胶的制备及染料吸附性能研究

通过原位溶液聚合法制备聚丙烯酰胺/2-丙烯酰胺-2-甲基丙磺酸/氧化石墨烯(PAM/AMPS/GO)纳米复合水凝胶。采用X射线衍射和红外谱图对复合水凝胶的结构进行了表征,并研究pH对水凝胶的染料吸附性能的影响。结果表明:GO与聚合物基体间存在较强的相互作用,能够均匀的分散在基体中。另外,复合水凝胶在中性溶液中对亚甲基蓝染料的吸附效果最佳,且最快达到吸附平衡。     

水热法氧化石墨烯改性环氧树脂的制备与性能

以膨胀石墨(100mesh)为原料,采用改进的水热法,经超声剥离制备了氧化石墨烯(GO)。通过X射线衍射、原子力显微镜及傅里叶变换红外光谱对GO结构进行表征,进而采用两相萃取法将制得的GO萃取到环氧树脂(EP)基体中。利用X射线衍射、扫描电镜等对GO/EP复合材料的断面形貌及GO在树脂中的分散状况进行表征,并进行了力学性能测试及动态力学分析。结果表明,GO厚度约为1.4nm,复合材料的力学性能较纯环氧明显提高,GO的加入使环氧树脂冲击断面转变为塑性断裂。当GO加入量为0.25%(质量分数)时,材料的冲击强度最高,强度值为55.17kJ/m2,提高了115%;拉伸强度提高了18%;断裂伸长率增加了78%。经动态力学分析可推断,GO的加入增强了其与环氧树脂间的界面粘接性,同时影响到环氧树脂聚合网络的形成。改性后的环氧树脂韧性大幅度增加。     

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 ...