195 research outputs found

    Continuous Biosynthesis of Noble Metal (Ag and Au-Ag) Nanoparticles and Its CFD Simulation

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    贵金属纳米材料在诸多领域具有广阔的应用前景,然而已有贵金属纳米材料的合成过程大都以间歇操作方式在釜式反应器中进行。目前实验室中利用化学法间歇制备贵金属纳米颗粒的技术已趋成熟,但随着反应釜体积的增大,体系的传热和传质问题凸显。连续流动反应器操作模式则可使制备过程在相对稳定的状态下进行,产品质量稳定,过程重复性好。因此,贵金属纳米颗粒连续制备技术(特别是在微反应器中)的研究,已引起研究者的关注和重视。但是,已有的研究侧重于过程条件对宏观结果的影响,对于反应器中传质、传热和界面等对纳米颗粒形成过程的影响及调控规律还缺乏充分的认识,特别是微尺度反应器内界面效应的作用效果及机理还没有被研究。随着人们对环...Noble metal nanoparticles have exhibited potential application in many fields. However, production of noble metal nanoparticles is mostly conducted in the batch tank reactor. Today, batch manufacture of nanoparticles using wet-chemical process in laboratory scale has achieved much success. However, with the increase of reactor dimension, heat and mass transfer in the reactor become a tough point w...学位:工学博士院系专业:海洋与环境学院_环境工程学号:2262010015360

    Design and Implementation of Management System for Special Equipment Inspection Business Based on Web

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    随着国民经济的快速发展,特种设备呈现快速化、大型化、高速化、复杂化、高危险性的发展趋势。特种设备是否安全,直接关系到人民的生命财产安全,建立特种设备检验业务管理系统,不仅是监督检验的业务和工作需求,也是国家和社会提高整体安全能力的需要。为了提高检验部门管理水平、节省人力物力,充分利用计算机技术、网络技术,建立符合自身的特种设备检验业务管理系统已经成为当务之急。 本文在对贵州省特种设备检验业务进行详细调研的基础上,进行了详细的需求分析,提出了基于Web的特种设备检验业务管理系统的解决方案。在系统需求分析阶段,利用结构化的分析方法进行了分析;在系统总体设计及实现阶段,利用J2EE技术框架,采用...With the rapid development of the national economy, special equipment showed as a rapid, large-scale, high-speed, complex, high-risk trends. The security of special equipment related to the lives and property of the people directly. So, the establishment of a special equipment inspection business management system, not only meet the business and work needs, but also the needs of the state and soci...学位:工程硕士院系专业:软件学院_工程硕士(软件工程)学号:X201223017

    Selective Ethylene Oligomerization Catalyzed by the Chromium Complex Bearing N-Tetrahydrofurfuryl PNP Ligand

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    通过胺基锂盐分离的方法合成了一种未有报道过的N-四氢糠基PNP配体E.; E分别与CrCl_3(THF)_3和Cr(CO)_6反应生成化合物[{Ph_2PN(CH_2OC_4H_7)PPh_2}CrCl_2(mu-Cl; )]_2(1)和[Ph_2PN(CH_2OC_4H_7)PPh_2]Cr(CO)_4(2).这三个化合物通过谱学和元素分析表征,化合物2进一步经; 过X射线单晶结构确认.在甲基铝氧烷(MAO)或其它助剂作用下,考察了1、2以及E/CrCl_3(THF)_3、E/Cr(acac)_3、E/Cr; Cl_2(THF)_2催化体系催化乙烯齐聚的性能.这些体系高选择性地催化乙烯四聚,最高活性为15.9 kg(product)/g(Cr)·h,; 1-辛烯的选择性最高可达63.6%.The N-tetrahydrofurfuryl diphoshinoamine (PNP) ligand (E) was synthesized by means of two-step salt elimination reactions where separation of the two kinds of the aminyl lithium salts for the respective reactions is necessary for obtaining a high yield of E. The ligand reacted with CrCl3(THF)(3) and Cr(CO)(6) to give P,P-chelation complexes [{Ph2PN(CH2OC4H7)PPh2} CrCl2(mu-Cl)](2) (1) and [Ph2PN(CH2OC4H7)PPh2] Cr(CO)(4) (2), respectively. Complexes E, 1 and 2 were characterized by spectroscopy and elemental analysis, of which complex 2 was further confirmed by X-ray crystallography. Upon activation with methylaluminoxane (MAO) or AlEt3, the catalyst systems including 1, 2, E/CrCl3(THF)(3), E/Cr(acac)(3) and E/CrCl2(THF)(2) were investigated. The best catalytic activity was achieved by 15.9 kg (product)/g (Cr)circle h in which a selectivity of 63.6% for 1-C-8 was obtained.National Natural Science Foundation of China [21473142, 21673191];; Innovative Research Team Program [IRT_14R31

    A New Methodological Research on Chaotic Encryption Based Watermarking

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    本文提出一种基于混沌加密的频率域数字图像水印新算法。将含有版权信息的二值图像作为水印,利用混沌密码对其进行加密。利用人类视觉系统(HVS)的特性,实现了水印在原始宿主图像小波域中的自适应嵌入。实验结果证明了对常见噪音和图像处理算法,该水印具有良好的不可见性和鲁棒性。In this paper,we propose an image digital watermarking algorithm based on chaotic encryption in frequency do-main. A binary image carrying copyright information is used as watermarking and is encrypted by a chaotic sequence cipher before it is embedded. Using characteristics of human visual system (HVS),watermark is embedded into the original image in DWT domain. The experimental results show that the watermarks are invisible and robust against noises and common im-age processing methods

    Improvement of n-butanol recycling technique in industrialized production of silicon dioxide as flatting agent

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    针对福建某工厂现有工艺生产二氧化硅消光剂过程,采用间歇蒸馏方式回收正丁醇存在时间长、效率低等问题,提出使用双塔精馏工艺进行改进以缩短正丁醇回收时间和提高回收效率。对改进后的工艺使用流程模拟软件进行模拟计算,获得了新的工艺条件参数。改进后,冷凝分层温度为85℃,精馏塔一塔釜液中正丁醇质量分数为99.62%,精馏塔二塔釜中正丁醇质量分数为0.31%。在此基础上搭建了实验室规模精馏装置并进行了验证试验,试验结果与模拟计算值接近,相对平均偏差为5.4%,表明模拟计算的结果可信。模拟计算结果为工业装置的优化提供了依据。改进后,正丁醇回收率将大幅提高,生产周期由原来的10 H缩短为5 H,能耗显著降低。采用此工艺生产二氧化硅消光剂可大幅降低过程成本。In order to reduce time cost and increase efficiency in n-butanol recycling,a double-column distillation process was suggested to replace the existing batch process due to its high time consumption and low efficiency.The improved process was simulated with flow simulation software.The calculated results show that in the improved process,condensing temperature is 85 ℃,the mass fraction of n-butanol at the bottom of Column 1 and Column 2 is 99.62% and 0.31% respectively.The verification tests on lab-scale distillation device were carried out.It shows that the calculated results are close to the tested results,and the average relative deviation is 5.4%,which indicates the calculated results are credible,and can provide a basis for optimization in industrialized plants.Now,n-butanol recycling efficiency increases largely and production cycle is reduced from 10 h to 5 h and energy consumption drops remarkably,so production cost can be largely reduced

    Optimization of Hydrometallurgical Purification for SiO_2 in the Process of Preparing Solar-grade Silicon

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    考察了Hf质量分数、H2C2O4质量分数、HnO3质量分数、酸浸时间、粒径、液体质量与固体质量的比值(简称液固比,下同)等因素对混酸法提纯SIO2工艺过程的影响,利用电感耦合等离子体发射光谱仪(ICP-OES)、场发射扫描电子显微镜(SEM)进行表征。结果表明,最佳工艺条件为:W(Hf)=2%、W(H2C2O4)=3%、W(HnO3)=30%、酸浸时间4 H、粒径100~120目、液固比4∶1、酸浸温度30℃。fE、Al、CA、P杂质的去除率分别达到99.99%、14.02%、73.27%、60.00%,经混酸法处理后SIO2中杂质总量的质量分数降至1.465x10-4。As a pre-treatment unit for preparing solar-grade silicon,hydrometallurgical route could remove most metallic impurities in silicon dioxide(SiO2) and raise the yield of the final product.Acid leaching of SiO2 could reduce the cost and energy consumption of industrialized development.Combined with high purity of reducing agent,the successor process of pyrometallurgy can also achieve "continuous casting".Factors such as the mass fraction of leaching agent,time,the particle size of SiO2,and the liquid-solid ratio were investigated,and the samples were characterized by means of ICP-OES,SEM,etc.The optimal reaction conditions were as follows:w(HF)=2%,w(H2C2O4)=3%,w(HNO3)=30%,reaction time 4 h,the average size of SiO2 powder particle 100~120 mesh,the liquid-solid ratio 4∶1,and room temperature 30 ℃.It was found that the final removal rates of impurities of Fe,Al,Ca,P could reach 99.99%,14.02%,73.27%,and 60.00% respectively and the mass fraction of total amount of impurities could be reduced to 1.465×10-4

    Study on removal boron from solargrade silicon with hydrometallurgy

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    湿法提纯作为冶金法制备太阳能级硅的前处理工序,可以去除大部分金属和硼杂质。研究了以氢氟酸-硫酸混合酸为浸出剂,有机溶剂甲醇作为后处理剂,去除硅粉中硼杂质的方法。采用电感耦合等离子体发射光谱仪(ICP)等对产品进行表征。酸浸过程优化工艺条件:硫酸质量分数为55%,氢氟酸质量分数为7%,酸浸温度为70℃、酸浸时间为4 H、液固质量比为8∶1。酸浸后可使硅粉中的硼杂质质量分数由6.893x10-6降至3.867x10-6,去除率为41.9%。在酸浸基础上采用有机溶剂甲醇作为后处理剂,杂质硼质量分数降至3.84x10-6,去除率为44.29%。从硼酸浸后形成的产物入手探索提高硼去除率的方法,实验验证了该方法的可行性,为研究湿法冶金预处理太阳能级硅提供了新的参考。As a pretreatment unit for preparing solargrade silicon(SG-Si) by metallurgic method,wet purification could remove most metallic impurities and nonmetallic impurities,such as boron.Experiment researched a new method to remove boron from SG-Si with mixed hydrofluoric acid-sulfuric acid as leaching agent and with organic solvent methanol as posttreatment agent.Samples were characterized by ICP and other analysis methods.When SG-Si powder had been leached at optimized conditions as follows:mass fraction of sulfuric acid was 55%,mass fraction of hydrofluoric acid was 7%,reaction temperature was 70 ℃,reaction time was 4 h,and liquid-solid mass ratio 8∶1,it was found that mass fraction of impurity boron in SG-Si was reduced to 3.867×10-6 from 6.893×10-6 and the removal rate was 41.9% after acid leaching;on the basis of the former procedure,mass fraction of impurity boron was reduced to 3.84×10-6 and the removal rate was 44.29% when treated with organic solvent.Experiment proved the feasibility of the method and provided a new reference for researching on the pretreatment of SG-Si by hydrometallurgy

    Development and fluidized simulation of semi-continuous pilot reactor for carbon nanotubes preparation

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    第一作者:朱丽(1980—),女,硕士研究生,从事化工过程开发与设计研究。E-mail:[email protected]。联系人:汤培平,教授。E-mail:[email protected]。[中文文摘]在间歇过程的碳纳米管制备实验基础上结合经验公式,开发设计了制备碳纳米管的半连续中试流化床反应器,结果表明:催化剂100 g、反应温度650℃时,甲烷平均转化率23.2%,碳纳米管产率为177.5 g/h,操作周期为间歇反应器的1/3,反应器可较好地实现碳纳米管制备功能。用计算流体力学方法对此反应器内的气固两相流化行为进行数值模拟,得到在工况条件下,最佳的催化剂用量为100 g、操作气速为0.15 m/s等工艺参数。[英文文摘]Semi-continuous pilot test fluidized bed reactor for carbon nanotubes preparation was designed and fabricated,base on experiments of batch fluidized bed reactor and repeated calculations.When reaction temperature is 650 ℃,reaction time is 4 h,velocity of CH4,H2,N2 are 0.1m/s,0.008 m/s,0.016 m/s,the yield of carbon nanotubes is 177.5 g/h,conversion of CH4 is 23.2%,production cycle is shortened by 2/3.The fluidization behavior of gas-solid fluidization process was calculated by using the computational fluid dynamics(CFD) package Fluent6.1.And the optimal condition for carbon nanotubes is that the velocity of CH4 is 0.1m/s,and catalyst is 100g

    Advances in Selective Ethylene Oligomerization Based on [PNP]-Ligand Chromium Catalysts

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    乙烯选择性三聚和四聚催化反应为制备1-己烯和1-辛烯提供了重要途径.在报道和披露的众多结构和组成的催化剂体系中,我们选择[PnP]配位骨架的铬催化剂体系,对其发展和应用进行了综述.论文以结构与催化性能的关联性为主线,阐述[PnP]骨架以及n和P上取代基的电子和立体空间效应对催化性能的影响.从目前的研究态势来看,[PnP]配位骨架的铬催化剂体系在乙烯选择性齐聚生产1-辛烯等线性α-烯烃方面具有发展潜力.The catalytic reaction for the selective ethylene trimerization and tetramerization provides a vital route to the production of 1-hexene and 1-octene.Among the numerous catalysts reported with diverse structures and compositions, we select the [PNP]-ligand based chromium catalysts and focus on illustration on their development and application.This contribution includes seven sections as ethylene(selective) oligomerization catalyst systems, [PNP]-ligand based Cr catalyst system, catalytic mechanism, ethylene oligomerization method, catalytic property, and conclusion and prospect, which will cover almost all of the [PNP]-ligand based Cr catalysts so far studied.In this article, we will mainly discuss the influence on the catalytic property owing to the electronic and/or steric characters of the skeleton as well as the substituents at both N and P atoms of the [PNP]-ligands.In view of the current advances in this field, this [PNP]-ligand based Cr catalyst system is of potencial in application for the production of LAO mainly as 1-octene.聚烯烃催化技术重点实验室基金(No.12DZ2260400); 国家自然科学基金(No.21473142); 教育部创新团队(No.IRT_14R31)资助项目~

    环状RNA circ_0120051通过miR-144-3p/IDH2轴抑制心肌成纤维细胞的纤维化表型研究

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    目的研究环形 RNA circ_0120051对心肌成纤维细胞的纤维化表型的调控作用和机制。方法通过实时萤光定量PCR(RT-qPCR)检测健康器官捐献者(n=24)与心力衰竭(HF)病人(n=21)心肌标本中 circ_0120051及其宿主基因溶质载体家族8成员A1(SLC8A1)的表达水平。核糖核酸外切酶(RNase R)消化实验鉴定circ_0120051的RNA稳定性。RT-qPCR检测circ_0120051在人心肌细胞AC16中的核质分布情况。利用腺病毒在C57BL/6乳小鼠心肌成纤维细胞(mCFs)中过表达circ_0120051,通过RT-qPCR和Western blot检测过表达circ_0120051对mCFs中纤维化相关基因表达的影响,利用细胞划痕实验检测对mCFs迁移能力的影响。通过RNA免疫共沉淀技术(RIP)验证circ_0120051与miR-144-3p间的结合作用,利用双萤光素酶报告基因实验鉴定miR-144-3p与靶基因异柠檬酸脱氢酶2(Idh2) 3’-UTR的结合位点。结果Circ_0120051在心衰病人心肌中表达显著增加,而其宿主基因SLC8A1表达无显著差异。Circ_0120051主要定位于人心肌细胞的胞质中。RNase R消化实验证实circ_0120051相对于线性SLC8A1 mRNA具有典型的环状RNA稳定性。过表达circ_0120051可抑制mCFs中纤维化相关基因表达和mCFs的迁移能力。RIP实验证实circ_0120051与miR-144-3p之间具有明显结合作用。在mCFs中转染miR-144-3p可促进纤维化相关基因的表达,并有效逆转circ_0120051对mCFs纤维化表型的抑制作用。双萤光素酶报告基因实验证实miR-144-3p与Idh2的3’-UTR存在结合作用。miR-144-3p可在转录水平抑制mCFs中Idh2表达,而过表达circ_0120051可增加mCFs中IDH2表达。在mCFs中转染miR-144-3p和Idh2的小干扰RNA(siRNA),可一致性地逆转circ_0120051对纤维化相关基因表达和mCFs迁移的抑制作用。结论Circ_0120051通过特异结合miR-144-3p并增加其靶基因IDH2表达来发挥抑制mCFs纤维化表型的作用
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