溶胶-凝胶法制备纳米氧化镁研究

以硝酸镁和硬脂酸为原料,用溶胶—凝胶(Sol-Gel)法制备得到了纳米氧化镁微粒,并用热重(TG)分析、X-射线粉末衍射(XRD)、红外光谱(IR)和透射电镜(TEM)等对该纳米微粒的结构与形貌进行了表征。结果表明,控制Mg(NO3)2和CH3(CH2)16COOH物质的量比为1∶4,在90℃反应20 min并于360℃热处理4 h,得到立方相氧化镁纳米微粒,形貌为椭球体,分散性好,平均粒径约为33 nm。     

三水合五氧化二钒纳米棒合成、结构表征和热稳定性研究

以NH4VO3为原料,在盐酸水溶液中采用水热法制备V2O5.3H2O纳米棒。利用X-ray diffraction (XRD)、Raman、扫描电子显微镜(SEM),透射电子显微镜(TEM)、热失重分析(TGA)表征手段,研究了V2O5.3H2O纳米棒结构、形貌和热稳定性。     

纳米钛酸锶及其系列功能材料研究概述

简要地叙述了钛酸锶及钛酸锶基纳米功能材料的制备、结构、性能及应用价值概况。并对其主要研究内容和国内外研究状况做了简单地介绍。     

不同生物质炭对土壤有机碳矿化及其活性碳的影响

通过室内培养实验,研究了2种木本材料(木荷和杉木)在3种热解温度下(350℃、550℃、750℃)制备的生物质炭对土壤有机碳矿化和微生物生物量碳(microbial biomass carbon,MBC)以及可溶性有机碳(dissolved organic carbon,DOC)的影响。结果表明:2种材料在不同热解温度下制备的生物质炭均显著增加了土壤CO_2-C累积释放量,并且添加木荷生物质炭处理的土壤CO_2-C累积释放量为添加杉木生物质炭处理的1.02~1.13倍。同一材料不同热解温度的生物质炭对土壤CO_2-C累积释放量的影响同样存在显著差异,且热解温度越低,累积释放量越高。此外,与对照土壤相比,生物质炭的加入显著降低了土壤MBC含量,但不同生物质炭处理之间土壤MBC的差异并不显著。相同热解温度条件下,添加木荷生物质炭的土壤DOC含量显著高于杉木生物质炭的;而同种材料条件下,不同热解温度制备的生物质炭对土壤DOC含量的影响则呈现热解温度越高土壤DOC含量越低的变化趋势。     

盐湖副产氯与固废粉煤灰制备高载氯（AlCl3）材料研究

青海柴达木盆地是我国盐湖资源的集中分布区,在钾、钠、镁、锂等大规模阳离子资源综合开发利用的同时,需要解决其中大宗阴离子"氯"的利用,即"氯平衡"问题,这关系着盐湖循环经济的发展。以工业固体废弃物—粉煤灰为载体,利用盐湖副产"氯"—盐酸,经过焙烧活化、酸浸、碱浸分离等工艺制备了载氯量在75%以上的高载氯材料(Al Cl_3),并通过XRD、SEM、TG-DSC等测试表征手段,对高载氯样品进行表征分析,然后对焙烧活化、酸浸等工艺进行分析研究以及参数优化,得到最佳的高载氯材料制备工艺,因而进一步解决了"氯平衡"问题,实现了"以废治废,变废为宝"的目的。     

紫外辐照条件下二维填料对聚丙烯耐老化行为的影响

采用水热法合成了二维层状材料——镁镍铁水滑石(MgNiFe-LDH),考察不同水热时间和水热温度对MgNiFe-LDH合成的影响,通过X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、扫描电镜(SEM)和热分析(TG/DTG)等测试方法,对样品的结构、形貌及热性能进行表征。将合成的MgNiFe-LDH添加至聚丙烯(PP)制备MgNiFe-LDH/PP复合材料,通过对材料加速老化测其力学性能,研究了添加MgNiFe-LDH前后材料机械性能变化。结果表明,当Mg~(2+):Ni~(2+):Fe~(3+)=2∶1∶1,水热温度140℃、水热时间24 h时,合成的MgNiFe-LDH为片状,形貌较为规整,颗粒粒径约为2μm。MgNiFe-LDH/PP复合材料经加速老化后,填充MgNiFe-LDH复合材料的抗老化性能优于纯PP,当MgNiFe-LDH的填充量为6 wt%复合材料拉伸强度不变,可明显提高PP的抗老化性能。     

特殊形貌MgO材料的研究

科技的发展、进步对材料的要求越来越高,随之而来的是各种特殊功能的复合材料的问世。作为复合材料,增强改性添加剂的特殊形貌MgO材料也获得了长足的发展。系统介绍了晶须MgO、纳米MgO及其他特殊形貌MgO的用途和制备方法。指出盐湖镁资源的综合利用和可持续发展并兼顾环境保护是今后研究开发的方向。     

纳米结构材料的模板合成技术

纳米材料的物理性质介于体相和原子 (或分子 )的性质之间 ,前者可以用经典物理学来说明 ,而后者却要用量子原理来解释。由于纳米粒子的小尺寸效应、表面效应和量子尺寸效应 ,使纳米材料具备不同于常规材料的新特性。纳米材料不仅在物质科学、材料科学基础研究方面有重要意义 ,而且有极广阔的应用前景。纳米科学与技术已被公认为 2 1世纪高科技的基础 ,其中如何实现对纳米粒子的结构控制和组装更是当前极富挑战性的课题。简要介绍模板合成技术及其在合成纳米结构材料 ,特别是纳米金属材料、电极材料和半导体材料方面的应用及进展     

海泡石对水菱镁矿/EVA体系阻燃性能的影响

水菱镁矿是一种新开发的高镁矿,可以作为阻燃填料使用。水菱镁矿作为单一填料时,阻燃效率较低。为了解决这一问题,使用海泡石(SEP)为协效剂,水菱镁矿(HM)作为阻燃剂,制备SEP-HM/EVA复合阻燃材料。对材料进行了极限氧指数(LOI)、垂直燃烧(UL-94)、锥形量热(CCT)和力学性能测试,研究了海泡石对该复合材料阻燃性能及力学性能的影响。研究结果表明:在水菱镁矿和海泡石总添加量为60%,其中海泡石为9%时,相比于未添加海泡石的复合材料,拉伸强度增加了51.59%,断裂伸长率增加了67.54%,LOI上升了3.5%,垂直燃烧等级均维持在V-0级别,热释放总量(THRR)降低了16.65%,烟释放总量(TSP)降低了22.93%。总的来说,在显著提高复合材料力学性能的同时,海泡石也能较好的提高复合材料的阻燃性能。通过该研究能够对水菱镁矿作为阻燃填料方面的应用提供新的思路。     

氧化锌纳米材料的合成、结构表征、光学及催化性能

以Zn(Ac)2.2H2O和NaOH为原料,十六烷基三甲基溴化胺(CTAB)为表面活性剂,采用水热法合成了不同形态的氧化锌。利用X-ray粉末衍射仪(Powder X-ray Diffractometer,XRD)、红外光谱仪(Infra-red Spectrometer,IR)、场发射扫描电镜表征所合成材料的结构和形貌。用紫外可见光度计、荧光光度计研究了氧化锌的光学性能。为了评估氧化锌的催化性能,进行了纳米氧化锌对乙酸和正丁醇合成乙酸正丁酯的催化实验。实验结果表明,纳米氧化锌对酯化反应具有很好的催化作用,催化活性与颗粒大小有一定的关系。     

Comparative studies on leaf epidermal micromorphology and mesophyll structure of Elaeagnus angustifolia L. in two different regions of desert habitat

In order to obtain qualitative and quantitative characteristics of leaf epidermal micromorphology and mesophyll structure to evaluate the responses of Elaeagnus angustifolia L. to different environment...     

氯氧镁水泥混凝土路面性能试验研究

氯氧镁水泥混凝土是由轻烧氧化镁、氯化镁溶液和一些砂石反应生成的一种气硬性胶凝材料。利用镁水泥混凝土修筑示范路面,通过回弹仪、X-Ray 衍射仪(XRD)、扫描电子显微镜(SEM)检测路面的抗压强度、相组成和微观结构。结果表明：修筑示范路面早期抗压强度增加很快,三天就能通车,后期基本保持稳定。修筑路面的主要相组成为5.1.8相,不随路面使用时间的延长而变化且其具有针状结构。     

西南地区水耕人为土诊断层土壤特性及SEM特征

对我国西南地区代表性水耕人为土诊断层土壤特性进行研究,并采用扫描电镜(SEM)进行土壤微形态研究,结果表明:不同母质和发育程度的水耕人为土,在土壤特性及在剖面上的变化特征都有明显差别.通过SEM观察研究表明:粗、细颗粒物质形态与矿物组成密切相关,如以薄片状、针条状等细粒物质为主的土壤,在水耕条件和外力作用下,易于定向、粘结聚合而引起土壤压实和板结.水耕人为土的微团聚体含量少而分散,对肥力的贡献有限.长期培肥的水耕人为土能够形成丰富的各类微孔隙和微结构类型,是调节土壤水、热、气和养分状况的主要机制.     

离子液体调控溶剂热合成TiO2纳米颗粒及紫外-可见光催化降解性能

以钛酸四丁酯(TEOS)、去离子水为原料,离子液体1-丁基-3-甲基四氟硼酸咪唑盐([Bmim]BF4)为表面活性剂,通过溶剂热法制备了锐钛矿相TiO2纳米颗粒。用X-射线衍射仪(XRD)、扫描电镜(SEM)、紫外-可见吸收光谱仪(UV-Vis)对产物的晶相、形貌和光学性能进行表征。为了评估光催化活性,并以甲基橙水溶液为研究对象,在紫外光照射下分析不同照射时间下光降解效率。结果表明,离子液体、去离子水和钛酸四丁酯的体积比为1.3∶1∶1.3时,反应所得到的TiO2具有较高光催化活性,明显优于未添加离子液体的产品,这一结果可归因于其具有较大的比表面积。     

From Lightning Rod to Community Asset? The Creation of a Protected Area in Northern California and its Evolving Relationship to a Nearby Community

Researchers have described shifting relationships between communities and Protected Areas (PAs), from excluding communities to consultative relationships to participatory models. This research focuses on a PA created on formerly industrial timberland that was the focus of conflict between environmental activists and the timber industry. In a nearby formerly timber-dependent community, we assessed community use and support of the PA, and its perceived purposes and benefits, through a survey of residents and interviews with key stakeholders. Despite intense conflict surrounding its creation, we found support for the PA, and our case suggests a new possible relationship between PAs and communities, which is mitigating and helping to resolve natural resource conflict. We also found that community well-being benefits of the PA were unclear; we suggest that PA management should include cultural, economic, and historical context in objectives and interpretive materials; and should work to create economic opportunities connected to the PA.     

A review of low-cost scanners†

Abstract

This paper summarizes the characteristics of 19 scanners costing less than Dfl20000 (US$10000). It also describes the completeness of scanning performed by three of these low-cost scanners (from Agfa, Cannon and Houston Instruments) and the accuracy of one (SCAN-CAD of Houston Instruments). It was found that complete scanning occurs with resolutions of half the minimum map line width and that maximum errors of 0-5 mm were achieved.     

Engineering properties of loess in Libya

A 1928 study of Tripolitania, indicated clearly the presence of loess-like deposits and described their nature, pointing out that 90% of the granular material was greater than 100 μm in diameter. Some authors suggest that there is a region of Peri-Sahara loess, although earlier observations indicate quite clearly that the Sahara region is free of loess. The proposed loess in North Africa, represented by soil samples from Libya, has been investigated. Undisturbed and remoulded soil samples representing two different types of loess have been collected from various locations in Libya. Samples represent Tripoli loess from the Jefara plain in the north west and Ghat loess from the Tahala region in the south west. The specific gravity, Atterberg Limits, grain size distribution and dry density were determined according to British Standard procedures (BSI, 1975). Grain size analysis for particles passing the No. 200 sieve (63 microns) was conducted using the Sedigraph technique. Geometrical characteristics of loess particles passing the 63 microns sieve were examined using a scanning electron microscope (SEM) technique. The hydrocollapsibility properties, with particular reference to their response to wetting under different stress levels, have been measured in single- and double-oedometer tests. The results of this investigation indicated that the Libyan loess has index properties and hydrocollapse behaviour similar to those of loess from many parts of the world, and that the material can be classified as silty loess in the Tripoli region and clayey loess in the Ghat area. The large particle sizes described in the 1928 study were not found. The Scheidig classification of the North Libya loess ‘Nachgewiesen definite’ is justified.     

Mg2+掺杂对正极材料LiFePO4/C结构和电化学性能的影响

以乙酸镁为镁源,用LiOH.H2O、Fe(NO3)3.9H2O、NH4H2PO4为原料通过水溶液法制备了掺杂Mg2+的LiFePO4/C正极材料。用XRD、SEM、恒流充放电测试、循环伏安(CV)和交流阻抗谱(EIS)方法,研究了Mg2+掺杂对LiFePO4/C的结构、形貌及电化学性能的影响。研究结果表明,Mg2+掺杂没有改变LiFePO4橄榄石型的结构;在0.1 C(1C=170 mAh.g-1)的充放电倍率下,Mg2+掺杂使正极材料首次放电比容量从153 mAh.g-1提高到159 mAh.g-1,经20循环次后,容量无损失;电化学交流阻抗显示,掺杂后材料阻抗Rct从463.1Ω减小到322.8Ω。     

微米级球形铜粉的制备

以抗坏血酸为还原剂,一定条件下还原硫酸铜氨溶液可以得到微米级球形铜粉。样品经X-射线衍射和扫描电子显微镜测定,并探讨了反应机理。     

Quaternary soil chronosequences on terraces of the Susquehanna river, Pennsylvania

Susquehanna River terraces are used to establish time lines along a 150 km reach of the river, from the Lower Piedmont to the edge of the Appalachian Plateau. This is achieved by generating soil chronosequences at two locations — Marietta, PA, in the Lower Piedmont, and Muncy, PA, near the glacial border on the boundary between the Valley and Ridge province and the Appalachian Plateau. These sites preserve the most complete record of fluvial incision on the Susquehanna River with flights of seven Quaternary terraces ranging in elevation from 3 m to 51 m above the modern river.Soil characteristics used to develop the soil chronosequences include complexity of horizonization, thickness of B horizon, clay content of B horizon, soil color, CBD extractable Fe, Al, and Mn, total extractable Fe, and clay mineralogy. Terrace age constraints are based on soil development, correlation to regional glacial stratigraphy, correlation to dated fluvial and glaciofluvial deposits, and by paleomagnetic analysis of sediments. Terrace ages at the Muncy site range from modern (< 150 ybp) to Middle Middle through Early Middle Pleistocene (∼ 300 ka to ∼ 770 ka). Marietta has terrace ages ranging from modern (< 150 ybp) to Early Pleistocene through Late Pliocene (∼ 770 ka to ∼ 2400 ka).