Two-step flotation recovery of iron concentrate from Donganshan carbonaceous iron ore

The flotation of pure and natural carbonaceous iron ore samples in the oleate flotation system was investigated. Starch can depress hematite effectively in a wide pH range, but cannot depress siderite efficiently in neutral conditions. The flotation recovery of pure hematite, siderite, and quartz in the oleate-starch-CaCl₂ system is significantly different when the slurry pH varies from 4 to 12. A novel two-step flotation process was developed for the separation of iron concentrate from Donganshan carbonaceous iron ore through which the siderite concentrate is first recovered and the high quality hematite concentrates with relative high iron recovery can be obtained in the second step flotation. The siderite concentrate may be utilized directly or undergo further concentration steps to increase iron grade.     

基于AHP法的中低收入群体住房改善方案分析

通过对中低收入群体住房现状分析,构建了以相对最佳的住房改善方案为目标层;以住户对住房产品的满意、社会人均住房水平提高的效率高、参与建设各方获得良好经济效益3方面组成准则层;以经济适用房、廉租房、双限房、普通商品住房构成方案层的AHP模型。进行赋值计算后,得出当前发展经济适用房是相对最佳方案,发展廉租房次之,发展双限房第三,发展普通商品住房排名最后的结论。     

基于Ohde理论的群桩极限端阻力计算公式

为从理论上探讨群桩中桩-土-桩的相互作用,分析该作用对群桩端阻力形成机理的影响,以建立在压缩机理之上的适用于单桩端阻力分析的Ohde理论为基础,提出了无黏性土中群桩极限端阻力的计算模式,据此分别推导出了群桩中边桩和中桩的极限端阻力理论计算公式.该公式能够定量反映桩距、桩径、桩端的入土深度和桩端以下土层的物理力学性质等因素对极限端阻力的影响,计算得到的群桩极限端阻力随相对桩距(桩距与桩径之比)减小而增加的规律与模型试验的实测结果基本一致.     

试论营养教育的重点人群

营养教育是健康教育的重要组成部分,是方便、有效的营养干预方式,许多国家都极为重视。我国目前营养教育应当首先关注重点人群,即营养弱势群体和对膳食与营养具有影响力的人群。营养弱势群体主要包括儿童青少年、孕妇乳母、老年人、慢性病患者、社会弱势群体,他们或处在生长发育的关键时期、或处在特殊的生理时期,或是健康状况不良的人群,或是营养状况较差的群体;对膳食与营养具有影响力的人群主要包括家庭主妇、团体膳食制作及管理人员。营养教育应从这些重点人群入手,提高其膳食营养意识,普及基本营养知识,改善大众营养状况,提升生命质量。     

阴离子表面活性剂HLB值与结构关系的拓扑化学研究

用拓扑方法研究阴离子表面活性剂HLB值与分子结构的关系。根据分子结构的特点,用距离矩阵表征分子中原子的链接性。通过回归分析得到一个结构基础明确的定量关系式,其复相关系数为0.999972。用拓扑方法研究阴离子表面活性剂HLB值与分子结构的定量关系是一种新的尝试,补充和完善了QSPR,引入的的拓扑参数Wn、S和Sn与HLB值相关性高,而且计算简便,物理意义明确,提高了预测结果的合理性和准确性,为众多的同名系列化合物HLB值的预测和评价提供了一种新的方式和手段。应用这一定量关系式,不仅能够合理表征阴离子表面活性剂的结构性能关系,而且有助于提示物质结构与性能之间的关系。为阴离子表面活性剂的研究、产品开发、实际生产和综合应用提供重要的参考数据。     

Silver catalysts supported over activated carbons for the selective oxidation of CO in excess hydrogen: effects of different treatments on the supports

Commercial activated carbon (AC) was used as a support either in its original form or after various modifications, giving diverse textural and surface chemical characteristics. The changes of these properties were monitored by N₂ adsorption–desorption isotherms, temperature programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS). Ag catalysts were prepared over the AC supports by a conventional wet impregnation method. The catalytic performances of supported Ag/AC catalysts in the selective oxidation of CO in excess H₂ were tested. The results indicate the textural and surface chemical characteristics are responsible for the different catalytic performances.     

Semi-continuous emulsion copolymerization of butyl methacrylate with polymerizable anionic surfactants

Two polymerizable anionic surfactants sodium 4-(ω-acryloyloxyalkyl)oxy benzene sulfonate (SABS-n, n=8 or 10) have been successfully used in the semi-continuous emulsion copolymerization with butyl methacrylate (BMA). After generating seeding particles in an emulsion consisting SABS-8 or SABS-10 and small amount of BMA using a redox initiator ammonium persulfate (APS)/tetramethylethylenediamine (TMEDA) at room temperature, most of BMA was added drop-wise to the polymerizing emulsion system during a period of 4-8 h. These emulsion copolymerizations produced nanosized latexes with high polymer/surfactant weight ratios up to about 12/1 and nearly monodisperse particles ranging from 18 to 33 nm in diameter. X-ray photoelectron spectroscopy results showed that SABS-n was significantly enriched on the surface of latex particles. The effects of concentrations of SABS-n, BMA, and APS/TMEDA and the latex characteristics during the continuous addition of monomer were studied. A possible polymerization mechanism was proposed.     

Advancing Africa’s Great Lakes research and academic potential: Answering the call for harmonized,long-term,collaborative networks and partnerships

The African Great Lakes (AGL) have rich fisheries and are renowned “biodiversity hotspots”. Consequently the AGL and the ecosystem services they provide, underpin the welfare and livelihoods of over 50 million people across 10 countries. Despite the recognized importance of the AGL, these vital ecosystems and their livelihood support systems are threatened by numerous anthropogenic stressors at local, regional, and global scales. Past and continued efforts to address critical challenges on these lakes are often short-term, parochial, disparate, and uncoordinated resulting in a lack of comprehensive and comparable scientific data and inadequate resources to influence evidence-based policy. Over the past two decades, several international workshops, conferences and scientific publications have identified the need for collaboration, knowledge sharing, and harmonization of research and management as key elements to enhance conservation efforts in the AGL. In this commentary, we introduce the African Center for Aquatic Research and Education (ACARE), which aims to strengthen research and provide the scientific evidence needed to make informed decisions related to sustainable fisheries and aquatic resource management in the AGL. To do this, ACARE will administer a highly collaborative network of experts with three long-term goals: (1) strengthen global and regional research partnerships; (2) establish transboundary and inter-jurisdictional lake advisory groups; and (3) build capacity of freshwater scientists through experiential education and public engagement.     

面向多区域防洪的长江上游水库群协同调度模型

长江上游水库群是长江流域防洪工程体系的重要组成部分,承担着水库所在河流、川渝河段以及长江中下游的防洪任务。长江流域面积广大,水系众多,洪水地区组成与遭遇十分复杂,防洪需求众多,防洪对象分散,且要兼顾发电、航运、供水、生态、库区安全等多种因素,水库群防洪调度面临大规模、多区域、多层次等协同调度技术难题。以长江上游25座控制性水库为研究对象,基于防洪格局和防洪任务将水库群防洪调度划分为核心、骨干和群组水库,阐明了水库群多区域协调防洪的调度节点和角色定位,提出了兼顾"时-空-量-序-效"多维属性的模型功能结构,构建了长江上游水库群多区域协同防洪调度模型,并在长江流域防洪调度形成示范应用,以挖掘长江上游水库群防洪调度潜力,进而提升长江流域防洪调度管理水平。     

Characteristics of coal sludge slurry prepared by a wet-grinding process

Coal sludge slurry(CSS) is an alternative fuel and a potential competitive method for sludge reduction.Based on the researches of coal water slurry, we studied CSSs by using a wet-grinding process with different types of regional municipal sludge(sludge) in an orthogonal experiment. The sludge type,sludge mixing proportion, dosage of dispersant, and grinding time were tested in this study. The results show that water content and its occurrence characteristics in the sludge have primary hindering influences on slurry ability. The range of fixed-viscosity concentrations with raw wet sludge is from 50.78%to 44.40%(by weight), while the range is from 53.35% to 51.51%(by weight) with dry sludge. All of the CSSs exhibit shear-thinning behaviors with different variation trends, especially the CSSs with more than 15%(by weight) raw wet sludge in it. Adding the same proportion of raw wet sludge increases the thixotropic properties of CSSs and the highest area of thixotropy loop is 3065 Pa/s, while the highest value of dry sludge is 1798 Pa/s. Hydrophilic group plays an important role in adsorbing water and building three-dimension networks with other particles, which is the main reason for CSS properties.Therefore, the mechanism can be used to find the way for making high quality CSS.