Cu-ZnO-CeO2催化剂组成对CO2加H2合成甲醇性能的影响

采用并流沉淀法分别制备了CuO-CeO₂（物质的量比为5：1）、CuO-ZnO（物质的量比为5：4）、CuO-ZnO-CeO₂（物质的量比为5：4：1）三组目标催化剂,通过X射线衍射（XRD）、氢气升温还原（H₂-TPR）、CO₂程序升温脱附（CO₂-TPD）、氮气吸附-脱附、X射线光电子能谱（XPS）、N₂O滴定表征技术对催化剂的物化性能进行了测试,并在高温高压微催化反应器中对催化剂进行活性评价。研究了CuO-ZnO-CeO₂组成对CO₂加氢合成甲醇的影响。结果表明,与二组分催化剂相比较,三组分CuO-ZnO-CeO₂催化剂物化性能及催化活性发生了很大变化,催化剂表面碱性位增强,热稳定性增强,CuO颗粒粒径变小,铜分散度以及氧空位浓度提高,最终催化活性显著提高。其中,CuO-ZnO-CeO₂催化剂中,CuO颗粒粒径为8.2nm,铜的比表面积为68.4m²/g,铜分散度为7.19%,甲醇的选择性和收率分别为48.6%和0.057mmol/（g·min）,催化剂活性较好。     

Effect of temperature and pH on interaction between bovine serum albumin and cetylpyridinium bromide: Fluorescence spectroscopic approach

The fluorescence spectroscopic technique has been efficiently employed to investigate the interaction between bovine serum albumin (BSA) and cetylpyridinium bromide (CPB) under different pH and temperature conditions. The binding constant, number of binding sites, thermodynamic parameters such as ΔG, ΔH, ΔS, and nature of binding forces between BSA and CPB were obtained by measuring the steady state fluorescence quenching of BSA by CPB. The experimental results showed that the fluorescence quenching of BSA by CPB was a result of the formation of CPB-BSA complex. The static quenching was confirmed from the Stern-Volmer quenching constant at different temperatures. The effect of CPB on the conformation of BSA was analyzed using synchronous and three-dimensional fluorescence spectroscopy. pH dependence complex formation between BSA-CPB is due to the interaction between cationic side chain of CPB and the net charge developed on BSA. The distance ‘r’ between BSA and CPB was obtained according to the fluorescence resonance energy transfer.     

Intrinsic localized modes in microresonator arrays and their relationship to nonlinear vibration modes

Intrinsic Localized Modes (ILMs) are defined as localizations due to strong intrinsic nonlinearity within an array of perfect, periodically repeating oscillators. Such nonlinear phenomena have been studied for a number of years in the solid-state physics literature. Energy can become localized at a specific location in a discrete system as a result of the nonlinearity of the system and not due to any defects or impurities within the considered systems. Here, such mode localization is studied in the context of microcantilever arrays and microresonator arrays, and it is explored if an ILM can be realized as a forced nonlinear normal mode or nonlinear vibration mode. The method of multiple scales and methods to construct nonlinear normal modes are used to study nonlinear vibrations of microresonator arrays. Investigations reported in this article suggest that it is possible to realize an ILM as a forced nonlinear vibration mode. These results are believed to be important for future designs of microresonator arrays intended for signal processing, communication, and sensor applications.     

OMS-2/Al2O3/堇青石整体式催化剂的制备及其催化性能研究

以Al₂O₃/堇青石蜂窝陶瓷为载体,氧化锰八面体分子筛(OMS-2)为活性组分,采用涂覆法制备了系列整体式催化剂。考察了黏合剂种类和活性组分涂覆次数对二甲醚(DME)催化燃烧性能的影响,并对催化剂进行XRD、BET、SEM、H₂-TPR、O₂-TPD等表征。结果表明,以甲氧基聚乙二醇为黏合剂经一次涂覆制备的整体式催化剂的性能最佳,活性组分OMS-2以相互交织的簇体均匀分布在载体上,并与Al₂O₃之间存在较强的相互作用。涂层的添加有效增加了催化剂的比表面积,提高了催化剂的性能,最佳催化活性t₉₀为257 ℃。     

热塑性聚合物复合材料蠕变性能的综述

热塑性聚合物复合材料(TPCs)由于其力学性能优异、产量巨大,并具有价格优势,已被作为重要的结构材料得到了广泛的应用.然而,由于聚合物的粘弹本性,其不可避免地会在外力的作用下产生随着时间延长而增加的形变,即蠕变.这种作用将对材料造成永久形变以及不可恢复的破坏,从而限制材料的应用.本文通过对TPCs蠕变的研究综述,详细探讨了TPCs蠕变的机理特征,分析了各类因素(诸如分子结构、填料、应力、温度等)对TPCs蠕变作用的影响规律.在此基础上,简明扼要的分析并提出了有助于获得抗蠕变性能优异的TPCs的方法.     

非线性项在零点和无穷远处非渐进增长的高维P-Laplacian半拟线性问题的全局分歧

本文将研究一般区域上高维p-Laplacian方程保号解的存在性:{u(x)=0,x∈ЭΩ,-div(φp(■u))=a(x)φp(u⁺+β(x)φp(u^-)+ra(x)f(u)),x∈Ω,其中Ω是R^N中一个有界且在其边界上光滑的区域,N≥2,1p-2s,a(x)∈C(Ω,(0,+∞)),u⁺=max{u,0},u^-=-min{u,0},a{x},β(x)∈C(Ω);f∈C(R,R)对于s>0,sf(s)>0成立.当f0■(0,∞)或f∞∈(0,∞)(其中f0=_|s|→0limf(s)/φp(s),f∞=_|s|→+∞limf(s)/φp(s)),且r≠0属于一定区间时,可以获得上述高维p-Laplacian方程保号解的存在性.我们用全局分歧技巧和连通序列集取极限的方法获得主要结果.     

产学研合作创新方式下政府补贴策略选择

创新补贴策略是政府鼓励企业创新的一种常见政策,考虑到企业内在的吸收能力与外部不同政府补贴策略方式的存在,本文以产学研合作创新方式为基础,通过建立三阶段博弈模型,利用模型解析与仿真分析讨论吸收能力与创新投入分配比例系数对政府补贴策略选择的影响。研究结果表明:无论政府采取哪一种补贴方式,均可以有效激励企业加大创新投入规模,并且企业的吸收能力与R&D投入、产量及社会福利均呈正相关关系;但是,吸收能力对利润及政府补贴的影响受限于补贴方式和企业的创新投入分配比例系数;此外,在创新产品补贴下,创新难度系数对政府补贴额度的影响并不明显,而创新产品补贴总体优于创新投入补贴。     

直接沉淀法制备纳米ZnO及表征

以硫酸锌和碳酸铵为原料,采用直接沉淀法制备了纳米ZnO,并探讨了浓度、温度、时间、洗涤液及操作方式等因素对样品的影响;采用GT-DTA、FT-IR、XRD、BET等对前驱物和纳米ZnO粉体结构和形貌进行了表征,结果表明:前驱物是[Zn5(OH)6(Co3)2],前驱物在300C培烧2h得到的纳米ZnO的粒径为15-22nm左右,分布较均匀、纯度高,并发现纳米晶须形状ZnO.     

离子交换树脂法制备纳米ZnS

以Zn(NO3)2·6H2O为锌源,Na2S为硫源,采用强碱性阴离子交换树脂法制备了纳米ZnS,并对形成的ZnS纳米粒子进行了XRD、TEM表征.XRD表征计算结果表明样品约为粒径6-10nm的小颗粒,TEM表征结果可观察到样品为由6-10nm的小颗粒团聚而成的50-80nm的大颗粒组成的.