石墨烯/磷酸银复合材料的制备及其光催化性能研究

采用改进Hummers法制备氧化石墨,将氧化石墨烯与硝酸银溶液搅拌处理一段时间后,滴加适量磷酸氢二钠溶液,制备得到石墨烯/磷酸银(GO/Ag3PO4)复合材料.利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射仪(XRD)、X射线光电子能谱仪(XPS)等手段对制备的复合材料进行了表征,并以有机染料罗丹明B的降解反应为模型评价催化剂在可见光下的光催化活性.测试结果表明,该方法不仅合成过程简单,而且石墨烯表面所负载的Ag3PO4纳米颗粒尺寸小、分散性好,与石墨烯的结合牢固.由于氧化石墨烯优异的吸附性能和对载流子的高迁移率,GO/Ag3PO4复合光催化剂显示出较高的可见光光催化活性和光稳定性.在可见光下对10mg/L的罗丹明B作用20min,降解率可达98%,降解效率较Ag3PO4颗粒提高近一倍.     

GO/Au/Ag复合材料表面形貌调控及其表面增强拉曼效应

表面增强拉曼散射光谱（SERS）因具有高灵敏及无损检测的特点,在化学检测领域受到广泛关注. 采用原位化学还原法,制备氧化石墨烯/金/银（GO/Au/Ag）复合材料,利用扫描电子显微镜（SEM）、X射线能谱仪（EDS）、紫光—可见分光光度计（UV）等手段对复合材料结构进行表征,并深入研究不同Au/Ag比例对纳米复合材料形貌和SERS的影响. 以罗丹明6G (R6G)为探针分子,研究纳米复合材料的形态对表面增强拉曼散射的影响. 研究结果表明GO/Au/Ag复合材料具有良好的SERS增强效果,且SERS信号强度与样品表面形貌以及Au、Ag含量（质量分数,全文同）有关. Au/Ag纳米颗粒表面粗糙度以及Au、Ag含量的提高可以显著增加GO/Au/Ag复合材料的SERS效果.     

减影提取焊缝缺陷算法

针对射线胶片焊缝缺陷自动检测技术普遍存在难以自动准确识别缺陷的问题,提出了一种基于减影法的焊缝缺陷智能检测提取方法.首先使用模糊增强方法对焊缝图像进行灰度变换,而后利用像素标记提取焊缝并保留其原始灰度值,再对提取到的焊缝滤波,去除其内部缺陷,衍生出背景图像,最后根据减影法得到缺陷,并且计算出缺陷的特征参数.结果表明,经上述方法检测后的缺陷图像,对比待测焊缝原图,可以较为准确地检测出焊缝中存在的缺陷,具有较好地自适应性和实用性.     

ZnO与银纳米颗粒表面等离子体耦合发光研究

将Ag离子注入到石英玻璃中形成Ag纳米颗粒并退火,用脉冲激光沉积法(PLD)在样品表面沉积ZnO薄膜,通过改变Ag纳米颗粒表面等离子体共振吸收强度,研究Ag纳米颗粒表面等离子体与ZnO薄膜的激子耦合效应.PL谱实验结果表明:Ag纳米颗粒与ZnO发生强烈的耦合使ZnO的发光增强,增强效果随Ag纳米颗粒等离子体的增强而增大,另一方面发光峰位发生红移,出现双峰现象.最后对耦合效应产生的机制进行了探讨.     

含裂纹石墨烯辐照修复研究

实际中生产出来的石墨烯不可避免的存在缺陷,缺陷对其优异的力学性能有着不可忽视的影响.利用分子动力学方法建立了C离子辐照含裂纹石墨烯的数值模型,先对含裂纹石墨烯进行辐照模拟,验证了辐照修复的可行性,分析了其修复原理,研究了辐照剂量和辐照能量对辐照效果的影响.通过拉伸模拟,将其力学性能与辐照前、完美石墨烯的进行比较,并对辐照后石墨烯在不同温度(0~1 000K)下进行了拉伸.结果表明:通过合理的控制辐照因素,可以用辐照手段实现对石墨烯裂纹的修复,从而提高其力学性能.辐照剂量和辐照能量影响着辐照效果.温度对辐照修复后石墨烯的力学性能也有较大的影响,随着温度的升高,其拉伸强度和拉伸极限应变近似线性降低.     

基于特征与形貌重构的轴件表面缺陷检测方法

针对轴件表面缺陷机器视觉检测方法中的水渍残留误检率高和人工复检效率低问题,提出一种基于特征与形貌重构的轴件表面缺陷检测方法. 对轴件工业高速线扫描图像进行预处理,基于改进的阀值迭代算法完成图像分割,通过去除背景、噪点和干扰提取缺陷图像. 建立基于曲线簇包络轮廓的轴件表面缺陷特征模型,结合分割图像各连通域的面积、面积占比、粗短度训练逻辑回归分类器,对凹坑、裂纹和麻点等轴件表面典型缺陷进行识别,并结合图像深度信息进行缺陷形貌重构,消除水渍等伪缺陷,提高轴件表面缺陷检测鲁棒性. 实验结果表明,所提出的轴件表面缺陷检测方法有效,具有较高的缺陷识别率和鲁棒性能,平均识别时间为3.69 s,缺陷轴加权识别率为98.86%,可以对3类典型缺陷和水渍进行准确识别.     

超临界混合流体辅助PtRuNi纳米粒子负载于低缺陷石墨烯的乙醇电催化氧化性能

通过较低浓度酸在冷凝回流的条件下处理石墨烯片层,使得石墨烯片层上具有充足但不过量的含氧基团。这些含氧基团既可以调节石墨烯在溶剂中的溶解性,又可以作为金属纳米粒子沉积时的成核点。再以制备好的低缺陷石墨烯(LDG)为原料,利用超临界CO2和甲醇混合流体的黏度低、密度可控和表面张力为零等优点,将PtRuNi、PtRu、Pt等金属纳米粒子成功负载到石墨烯表面。通过X-射线衍射仪(XRD)、透射电子显微镜(TEM)、能量色谱仪(EDS)、X-射线光电子能谱(XPS)、拉曼(Raman)等方法分析了PtRuNi/LDG复合物的结构特征。并用电化学的方法比较了PtRuNi/LDG,PtRu/LDG,Pt/LDG与PtRuNi/XC-72,PtRu/XC-72,Pt/XC-72对乙醇氧化的电催化活性,结果显示,所制备的PtRuNi/LDG具有更高的乙醇电催化效能。     

BPEL静态缺陷检测方法

为了对广泛流行的业务流程执行语言（BPEL）进行静态缺陷检测,深入研究了BPEL程序中可能存在的各种缺陷,提出了面向缺陷模式的BPEL静态检测方法. 面向缺陷模式检测的方法采用扩展有限状态机对缺陷进行建模,通过属性状态变迁条件判断缺陷状态,并在所有控制流汇合节点上合并相同属性状态的状态机实例,从而避免了冗余判断的问题. 该方法已用于BPEL的缺陷检测系统中. 实例验证结果说明,采用该方法进行测试有效可行,可用于提升流程的可靠性和准确性.     

石墨烯/h-BN面内异质结构热输运的分子动力学研究

采用非平衡分子动力学方法探究石墨烯/h-BN面内异质结构界面热导的影响因素,讨论了单空位缺陷和Stone-Wales (SW)缺陷在近界面不同位置时的声子热输运活动。模拟结果证明,当h-BN一侧单空位缺陷远离界面,界面热导随之降低; SW缺陷则由共价键类型和位置决定其对界面热导的影响,由此揭示缺陷的类型和位置对界面热导带来的调节作用。此外,讨论了界面处存在单空位缺陷时,温度变化影响界面热导背后的潜在机理。本研究对微观尺度下的二维异质结构材料的热导性能提供理论参考和实验指导。     

石墨烯带正常-超导结的量子输运

基于非平衡格林函数(non-equilibrium Green's function,NEGF)和密度泛函理论(density functional theory,DFT),从第一性原理出发研究Armchair型和Zigzag型的石墨烯带正常-超导结的电子输运性质,计算了缺陷对这两种正常-超导结输运性质的影响.计算表明,对无缺陷正常-超导石墨烯带,在超导能隙内,Andreev反射系数TA恰好等于正常石墨烯带的电子透射系数TN.当石墨烯带存在缺陷时,Andreev反射系数TA不再是一个常数,而在超导能隙边缘出现两个尖锐的峰,其峰值大于正常系统的电子透射系数.在超导能隙之外,Andreev反射系数TA逐渐减小为0,准粒子的正常隧穿几率T1逐渐增大,且趋于无超导下的正常系统的电子透射系数TN.不同缺陷构型对石墨烯带中载流子的输运过程影响不同.如果缺陷的存在对正常石墨烯带电子散射过程影响越大,则其对正常-超导体系中的Andreev反射和准粒子散射影响也越大.     

Dendrimer Templates for the Formation of Silver Nanoparticles

Synthesisandcharacterizationofmetalnanopar ticles,especiallynoblemetalnanoparticleshaveat tainedgreatconsiderationowingtotheiroptical,elec tronic,andcatalyticproperties[1,2].Theabundant literatures[3,4]showthattheoptical,electronic,and catalyticpropertiesofthemetalnanoparitclesdepend ontheirsizeandstability,whichstronglydependon themethodandexperimentfollowed.Soitisimpor tanttochooseapropermethodtopreparenoble nanoparticles.Dendrimers[5]arehighlybranched macromoleculesthatconsistofacentralcore…     

SnO2-CuO/graphene nanocomposites for high performance Li-ion battery anodes

The nanocomposites of SnO2-CuO/graphene are synthesized via a two-step method.CuO nanorods are firstly uniformly loaded on the graphene nanosheets,and then SnO2 nanoparticles are coated on CuO nanorods.SnO2-CuO/graphene nanocomposites exhibit high cyclability and capacity as anode of Li-ion battery.After 30 cycles,the capacity can maintain at 584 mAh g-1 at0.1C rate(10 h per half cycle).The high performance can be ascribed to the synergistic effect among SnO2 nanoparticles,CuO nanorods and graphene nanosheets.The results manifest that the nanocomposites of SnO2-CuO/graphene are very suitable for Li-ion battery anodes.     

Effect of Sequential Ions Implantation on Structure of Cu, Ag Nanoparticles

The preparation of metal nanoparticles composites by Cu, Ag ions sequential implantation is studied. The formation of Cu, Ag nanoparticles has been evidenced by grazing incidence X-ray diffraction, extended x-ray absorption fine structure and transmission electron microscopy. With the increase of Ag ion implantation dose, the size and density of Ag nanoparticles increase significantly.     

Completely green synthesis of Ag nanoparticles stabilized by soy protein isolate under UV irradiation

A completely green pathway for the preparation of Ag nanoparticles was proposed, by using soy protein isolate (SPI) as stabilizer under UV irradiation and H2O as the environmentally benign solvent throughout the preparation. Transmission electronic microscopy (TEM) and zeta potential characterization results indicated that the Ag nanoparticles were stable and well dispersed with an average diameter about 13 nm, and X-ray diffraction (XRD) analysis of SPI/Ag composite nanoparticles confirmed the formation of metallic silver. UV-Vis spectrum showed that the Ag nanoparticles dispersion solution had the maximum absorbance at about 430 nm due to surface plasmon resonance of the Ag nanoparticles. Infrared spectroscopy confirmed that the polypeptide backbone of SPI was not cleaved during the conjugation process and that some active amino groups were oxidized. The SPI/Ag composite nanoparticles have excellent antibacterial activity against two representative bacteria, staphylococcus aureus (Gram positive) and escherichia coli (Gram negative) in the presence of SPI.     

Ag recovery from copper anode slime by acid leaching at atmospheric pressure to synthesize silver nanoparticles简

In this paper, recovery of silver from anode slime of Sarcheshmeh copper complex in Iran and subsequent synthesis of silver nanoparticles from leaching solution is investigated. Sarcheshmeh anode slime is mainly consisted of Cu, Ag, Pb and Se. Amount of Ag in the considered anode slime was 5.4% (by weight). The goal was to recover as much as possible Ag from anode slime at atmospheric pressure to synthesize Ag nanoparticles. Therefore, acid leaching was used for this purpose. The anode slime was leached with sulfuric and nitric acid from room to 90 °C at different acid concentrations and the run which yielded the most recovery of Ag was selected for Ag nanoparticles synthesis. At this condition, Cu, Pb and Se are leached as well as Ag. To separate Ag from leach solution HCl was added and silver was precipitated as AgCl which were then dissolved by ammonia solution. The Ag nanoparticles are synthesized from this solution by chemical reduction method by aid of sodium borohydride in the presence of PVP and PEG as stabilizers. The synthesized Ag nanoparticles showed a peak of 394 nm in UV–vis spectrum and TEM images showed a rather uniform Ag nanoparticles of 12 nm.     

Formation of Copolymer-Ag Nanoparticles Composite Micelles in Three-dimensional Co-flow Focusing Microfluidic Device

A novel method was presented to create composite micelles of amphiphilic copolymers and Ag nanoparticles(NPs) in a three-dimensional co-flow focusing microfluidic device(3D CFMD). Self-assembly of the copolymers was initiated by the fast mixing of water and a blend dispersion of hydrophobic Ag NPs and amphiphilic copolymers. At the same time, the hydrophobic Ag NPs enter the core of copolymer micelles, based on the hydrophobic interaction. The copolymer-Ag NPs composite micelles have a core-shell structure with copolymer shell and Ag NPs core. COMSOL Multiphysics is used to simulate the concentration distribution of copolymers and Ag NPs under different flow rates. Co-assembly microfluidic conditions are determined based on simulation results. Under suitable microfluidic conditions, both block copolymers and gradient copolymers can co-assemble with hydrophobic Ag NPs to form composite micelles, respectively. This microfluidic coassembly method will have a good prospect in the preparation of composite micelles of amphiphilic copolymers and metal nanoparticles.     

基于非下采样Contourlet域高斯混合模型的布匹瑕疵识别算法

针对经典瑕疵检测算法不能很好地描述瑕疵特征和不易区分相似类瑕疵类别的问题,提出了一种非下采样Contourlet域高斯混合模型的布匹瑕疵识别算法。首先利用非下采样Cont-ourlet变换(NSCT)得到图像的多方向、多尺度和平移不变表示,并通过代价函数挑选一个最优子带;由于子带瑕疵和非瑕疵区域系数差别较小,很难直接选取阈值,采用标准差法可以有效避免这个问题,获得比较准确的检测结果;然后计算瑕疵区域的统计特征得到特征向量;接着引入最小误分率函数,联合估计样本的高斯混合模型参数;最后采用贝叶斯分类器进行分类。在9类瑕疵上的实验结果表明,本文算法与几种经典算法相比得到更高的分类正确率。     

一锅法制备聚乙烯醇载银海绵及其催化性能

以水为溶剂、以聚乙烯醇（PVA）为还原剂和纳米银的载体,通过一锅法制备了一种聚乙烯醇载银（PVA/Ag）海绵并将其用于催化还原对硝基苯酚（4-NP）。采用扫描电子显微镜、傅里叶变换红外光谱、拉曼光谱、X射线衍射、热重分析分别表征了PVA/Ag海绵的形貌、组成与结构,并用紫外-可见光谱分析了其催化还原4-NP的性能。结果表明:一锅法制备的PVA/Ag海绵具有三维多孔结构,有效地抑制了纳米银颗粒的团聚,使得纳米银颗粒分布均匀,在4-NP还原中具有良好的催化性能。当4-NP的浓度为0.2 mmol/L时,载银量为2.2%的PVA/Ag海绵在14 min内完成催化,催化效率达到98%以上。因此,本文制得的PVA/Ag海绵具有制备简单、催化效率高等特点,在污水处理领域具有潜在应用前景。