葡萄糖还原浸出低品位钴土矿工艺及动力学研究

采用葡萄糖为还原剂,在硫酸体系中进行低品位钴土矿进行直接浸出,研究浸出过程的工艺条件和动力学。实验结果表明:在硫酸初始浓度1.6 mol/L,葡萄糖初始浓度5 g/L,反应温度95℃,浸出时间6 h,液固比3∶1的条件下,钴土矿中Co和Mn的浸出率可同时达到99%以上。动力学研究表明:钴的浸出过程在75~95℃内符合未反应核缩减模型,浸出过程主要受内扩散步骤控制,浸出表观活化能为21.03 k J/mol。     

利用鸡蛋壳制备葡萄糖酸钙的研究

以鸡蛋壳为钙源,制备葡萄糖酸钙，考察了原料配比、反应物浓度、反应温度、时间等因素对产物产量的影响。结果表明，在反应温度60℃、反应时间60min、葡萄糖酸浓度为0.75mol/L、葡萄糖酸溶液与水合物Ca（OH）2作用时，以等当量作用，产率最高，产品收率可达95%以上。     

正交试验法优选碳酸氢钠制备碳酸镨钕的研究

本研究以工业碳酸氢钠作沉淀剂,沉淀氯化镨钕料液,研究了温度、碳酸氢钠用量、反应时间对沉淀的收率及质量的影响。结果表明,最优的试验条件为:反应温度50℃;反应时间3 h;碳酸氢钠与稀土的重量比1.65:1.00;碳酸氢钠的浓度2.00 mol/L。沉淀的碳酸镨钕用原子吸收分光光度计(AAS)、722型可见分光光度计等分析仪器进行检测,其中的关键杂质指标可达到Cl~-0.025 0%、Na_2O 0.021%,烧后REO 99.5%。     

低品位氧化锌矿在NH4Cl溶液中的浸出研究

本文研究了低品位氧化锌矿在NH4Cl溶液中的浸出,并重点分析搅拌速度、NH4Cl浓度、反应温度、液固比、反应时间对异极矿在NH4Cl溶液中浸出的影响.结果表明,提高NH4Cl浓度、反应温度和液固比可以极大提升锌浸出率,搅拌速度对锌浸出率的影响较小.在温度155℃、NH4Cl浓度5.5 mol/L、液固比9:1、搅拌速度...     

废镍钼催化剂低温焙烧常压碱浸试验研究

主要探讨了废镍钼催化剂的焙烧-碱浸出的工艺条件.首先采用低温焙烧,再用碳酸钠漫取.分析了焙烧条件、浸取条件对浸取率的影响.试验结果表明:在焙烧温度为650℃、焙烧时间为3h、碳酸钠浓度为30g/L、浸取温度85℃、浸取时间3h、液固比为6∶1时,钼的浸取率达到90％以上,铝浸取率在3％以下(浸出液中铝浓度低于0.01g/L).该工艺具有能耗低,浸取率高等优点,具有潜在的应用前景.     

废干电池制备锰锌铁氧体中硫酸盐溶液脱除钛钾钠的研究

研究了在废干电池和钛白厂废硫酸制备锰锌铁氧体过程中硫酸盐溶液脱除钛钾钠的影响.实验结果表明,以双氧水作为氧化剂,在15L的硫酸盐溶液,控制反应温度为95℃,pH值为1.5,反应时间为2h条件下,加入100mL双氧水,净化后溶液中的钛、钾、钠离子浓度分别为0.005g/L、0.005 g/L、0.084 g/L,达到制备高档锰锌铁氧体产品的要求.     

MnOx/Al2O3催化臭氧氧化处理含氰废水

本研究采用浸渍法，以Mn(NO₃)₂为前驱体、γ-Al₂O₃为载体，制备负载型金属氧化物催化剂MnO_x/Al₂O₃，用于处理氰化废水中的氰离子。其间考察了臭氧投加量、催化剂制备工艺参数、催化剂投加量、溶液pH等因素对废水中氰化物去除效率的影响。试验表明，从制备催化剂的最佳工艺参数来看，Mn目标负载量为8%，焙烧温度为500℃，焙烧时间为4 h。在优化的试验条件下，氰化物浓度可以从5.4 mg/L降到0.2 mg/L以下。反应机理研究表明，MnO_x/Al₂O₃催化臭氧氧化处理氰化废水遵循羟基自由基机理。反应动力学分析表明，该反应符合一级反应动力学模型，表观反应速率常数为0.031 6 min^-1。     

姜黄素在玻碳电极上的电化学行为研究

姜黄素是从姜科植物姜黄中提取的多酚类物质,由于其具有多种药理活性,因而有广泛的应用前景。本实验利用玻碳电极在不同条件下,对姜黄素的电化学行为进行研究,并对影响其电化学行为的不同参数进行优化。实验结果表明在pH为4.2条件下,姜黄素在玻碳电极上具有良好的电化学响应性能。利用差分脉冲伏安法对姜黄素进行定量测试,发现其氧化峰电流与其浓度在1.0×10~(-5) mol/L~8.0×10~(-7) mol/L范围内呈良好的线性关系,检出限为6.5×10~(-8) mol/L。与目前其他检测方法相比,具有较高的灵敏度。     

锌电解液净化铜渣除氯工艺研究

本文采用铜渣法脱除锌电解液中的氯,并考察了反应温度、溶液酸度、铜渣用量、初始铜离子浓度和反应时间对除氯效果的影响,以优化除氯工艺参数。试验结果表明,在初始溶液硫酸酸度10 g/L,反应温度60℃,铜渣3倍理论用量,溶液初始铜离子浓度1.5 g/L,反应时间1 h的优化条件下,溶液中氯离子脱除效果好,氯离子脱除率可达88%,溶液中氯离子含量降至74 mg/L,满足电解要求。     

40～50 ℃污泥厌氧消化性能探究

本文以中温(37 ℃)厌氧消化反应器的污泥为接种泥,以脱水污泥为基质,通过半连续反应试验,对污泥40～50 ℃厌氧消化系统的性能进行初步探究。试验结果表明,47 ℃产甲烷率为0.98 L/d,42 ℃产甲烷率为0.80 L/d,二者都高于37 ℃和55 ℃反应器。系统关于微生物的多样性分析结果表明,细菌方面,37 ℃和42 ℃的种群组成没有变化,种群比例略微有所变化。47 ℃和55 ℃出现了Coprothermobacteraeota和Thermotogae两个新菌种,其比例随温度的升高而变大;古菌方面,37 ℃和42 ℃的种群组成没有变化,乙酸发酵型甲烷菌Methanosarcina种群比例达到90%。47 ℃系统里的古菌种群几乎完全被氢发酵型产甲烷菌Methanobacterium取代,其占比为80.8%。而在55 ℃,Methanothermobacter成为新的优势菌群,是一种嗜高温的氢发酵型产甲烷菌,其比例达到78.4%,Methanosarcina几乎不存在。     

On the Major Transformation of the Asia-Pacific Regional Structure北大核心CSSCISSCI

Recent years have witnessedsignificant changes in the Asia-Pacific regionalstructure featuring the shift in power balance among related countries as well as adjust-ments in their respective regional strategies. So what is the prevailing trend in thistransformation and what kind of regional order will likely emerge in the future？ To an-swer these questions, the paper tries to explore the following dimensions： the evolvingregional context, shift in power balance and power conversion, geo-political and geo-e-conomic developments and interactions between them, and evolving regional order. Asthe study shows, the broadening of regional geographical scope, the rise in the numberof actors involved, as well as changesin the relations among them, have combined tocast a pluralistic and complex flavor to the regional structure. While the power balanceamong China, the United States and Japan shifts, and power conversion is also occur-ring. China and Japan are paying increasing attention to their security roles, whereasthe United States under the Obama administration laid more stress on expanding itsgeo-economic clout. In spite of the intensifying geopolitical competition among China,the United States and Japan in recent years, a Sino-US strategic compromise-whichholds the key to regional geopolitics-isother front, some kind of geo-economicmore likely to take place in the future. On thecooperation will probably emerge. In the longerterm, it will be the geo-economic trend thatwill prevail over the geopolitical trend inthe region. Finally, the future evolution of regional order wiI1 mainly follow the eco-nomic logic, accompanied by the dilutionof its hegemonic and hierarchical nature.Hence, a pluralistic and complex regional community will emerge.     

The German Hanse and Bergen – new perspectives on an old subject

Abstract

The Hanseatic League and her kontors (trading posts) were an integral part of the medieval trade system in Northern Europe. Hanse merchants dominated many markets in this region and managed to maintain a monopoly-like role in towns like Novgorod and Bergen for many centuries. Consequently, one focus of historical research about the Hanseatic League lay on the mechanisms that enabled the Hanse merchants to keep that strong of a position for such a long time.

This article is part of the discussion about this topic. Based on Lübeck merchants with business interest in the Norwegian town of Bergen, the so-called Bergenfahrers (Bergen travellers), it will give new insights into the Hansards' economical and social organization. The three main points are (a) the integration of the Bergen market in the Hanseatic trade network as an intermediary trading place on the vivid East–West route of Hanse trade; (b) the importance of the Bergenfahrers within the Hanse merchants' economical, social and political networks; and (c) the structure of the Bergenfahrers network patterns in the late Middle Ages.

In addition to new insights into the important role of Bergen and the Bergenfahrers within Lübeck's and the other Wendish Hanse towns' trading system, this articles provides further proof for the usefulness of the methods of Social Network Analysis in medieval economic research.     

Organization and incentives in the age of sail

The British Navy in the age of sail was the most successful bureaucracy of its time. Its organization and incentive structures differed importantly from contemporaneous private sailing ventures, but closely resembled those of today’s large corporations. To induce efficient effort, the navy used a hierarchical tournament, in which sailors competed for higher pay that came with promotions based on relative performance. Promotion probabilities, the option value of future promotions, and the higher effort required of men in higher ranks and on larger vessels, combined to yield a highly skewed pay structure.     

Financial Reporting and Trade Credit: Evidence from Mandatory IFRS Adoption*

We investigate the effect of mandatory IFRS adoption on trade credit. We document that firms in countries that adopt IFRS receive more trade credit from their suppliers, consistent with improved financial reporting quality and comparability playing a role in facilitating informal financing. This increase is larger for countries with a low level of societal trust, a poor pre‐IFRS‐adoption information environment, and stronger legal enforcement. These cross‐sectional results suggest that the conditions under which higher‐quality information is made publicly available affect suppliers' decisions to provide trade credit. This increase is also larger for firms with greater exposure to foreign markets, a finding that highlights the importance of more comparable international financial reporting standards in facilitating cross‐country trade credit. We also find that IFRS adoption has a stronger positive effect on trade credit for firms with greater liquidity needs. Finally, we find that firms in countries that adopt IFRS also extend more trade credit to their customers. Overall, our results support the notion that financial reporting can have a causal effect on trade credit.     

中俄经济技术合作面临新机遇

中俄在十年内把各自的GDP翻一番的目标,为发展中俄经济技术合作提供了机遇.仅仅依靠商品贸易的增长很难大幅度提升中俄经贸关系,需要全面开展经济技术合作,特别是加强在自然资源开发、跨国投资、军工技术和产品贸易领域的合作.     

INFRASTRUCTURE POLICY IN INDONESIA, 1965–2015: A SURVEY

This survey, first, provides an overview of the main developments in the infrastructure sector in Indonesia during the past five decades and, second, considers what the main policy and management bottlenecks in infrastructure appear to be. The overview of main developments indicates that, in broad terms, most parts of the sector have expanded considerably but that the needs remain acute for further expansion and for attention to the maintenance of existing facilities. Demand for infrastructure is high, especially since the regulated prices set for infrastructure services are often low. Access is often difficult, however, because of shortages of infrastructure, and quality is often unsatisfactory because of poor maintenance and indifferent management. These problems of access are exacerbated by the regulation of prices. This overview also points to the markedly different performances of industries in which pro-competitive policies have been applied and those in which more traditional policies of close regulation have restricted the operation of markets.     

Integrated educational management for the universities

The research model investigates the integrated form of educational management for the universities. To enhance the operations, generate quality outcomes for the well-being of the society, this exploratory study depicts the two wings for the universities in four aspects including education development, education assessment, research development and research assessment. For the better understanding of education and research wings of the universities, the researchers identify different factors namely programs establishments, university culture, faculty capabilities and facilities those have been formularized by the structural equation modeling （SEM） through AMOS. The survey questionnaire was developed and analyzed the reliability and validity of the tools. The conceptual model for the universities provides a novel approach for decision makers to review and appraise their performance toward fulfillment of ultimate goals, i.e. producing high-caliber graduates and high-impact research outcomes for the betterment of the society. This research represents two contributions to the society including human resource contribution and research contribution.     

基于DEA方法的我国证券公司效率的实证分析

选取了具有一定代表性的证券公司为样本,根据2006年至2008年的财务数据,运用DEA的C2R模型和BC2模型来分析计算他们的技术效率、纯技术效率、以及规模效率。然后通过对不同证券公司的分析,揭示我国证券公司整体上的现状。