碳气凝胶的制备及在水处理中的应用进展

碳气凝胶作为一种新型纳米级多孔碳材料,具有孔隙率高,比表面大,密度范围广等优点.由于其连续的三维纳米网络结构可以在介观尺寸内控制,广泛用于催化剂载体、超级电容器的电极、隔热材料、吸附剂等.传统碳气凝胶的制备主要以间苯二酚和醛为原料,经过溶胶、凝胶、酸洗老化、溶剂交换、干燥、碳化等步骤制得.随着人们对反应原料范围的扩大和制备条件的改变,碳气凝胶表现出新的性能,它的适用范围也不断扩大.本文综述了碳气凝胶的制备方法、反应机理和在水处理中的应用进展,并探讨了未来碳气凝胶制备的改进方向及应用前景.     

神奇的碳海绵

最近,浙江大学从事高分子材料研究的科研人员制备出了一种超轻气凝胶——碳海绵,又被称为全碳气凝胶。据称,它的同态材料密度为每立方厘米0．16毫克,仅为空气密度的1／6。在电子显微镜下,     

壳聚糖/氧化铝复合气凝胶的制备和表征

以壳聚糖和无机铝盐AlCl3.6H2O为原料,通过溶胶-凝胶方法,分别用CO2超临界干燥手段及冷冻干燥手段制备了新型的壳聚糖/氧化铝复合气凝胶.结果表明,壳聚糖的含量影响复合气凝胶的比表面积及孔体积等性质,随着壳聚糖含量的增加,混合气凝胶的比表面积逐渐减小.不同的干燥方法对复合气凝胶的比表面积等性质也有明显的影响.     

多孔阳极氧化铝研究综述

多孔阳极氧化铝由于其在制备纳米结构材料方面的重要应用而引起了人们的广泛关注．一般认为：多孔阳极氧化铝多孔层的膜胞以六角形紧密堆积排列，每个膜胞中心都有一个纳米级的微孔，孔径大小和孔间距可以通过制备条件加以控制．文章综述了多孔阳极氧化铝的结构、合成、形成机理和应用等方面的研究现状。     

科技阅读二则

“火星探路者”曾把一辆叫做“旅游者”的6轮车送上了火星表面。火星是一个寒冷的世界,大多数地区在大部分时间内比地球上南极还冷在这样低的温度下,“旅游者”能正常工作,得益于气凝胶。气凝胶是一种特殊的固体材料,被称为“固体烟雾”、“固体空气”或“固体泡沫”。它由96%的空气和4%的二氧化硅与碳制造而成。在显微镜下观察,它的结构像一条精美的珍珠项链,每颗“珍珠”几十纳米大小,“珍珠”之间的细孔,直径在1—100纳米之间。其密度只有空气的3倍,可与云雾相比拟。气凝胶隔热性能强,吸附力大,强度高,重量只有玻璃的千分之一,因此在航天…     

白云母/纳米TiO_2复合光催化材料制备及应用

针对纳米TiO2在应用中存在易团聚、难回收等缺点,选用白云母为载体,采用溶胶-凝胶法制备了白云母,纳米TiO2复合光催化材料．用制备的材料在紫外光照射条件下处理直接铜络合偶氮染料废水．结果表明：500℃焙烧的复合材料对废水的光催化脱色率达到61％以上．该复合材料有望在废水处理、环保涂料领域得到应用．     

白云母／纳米TiO2复合光催化材料制备及应用

针对纳米TiO2在应用中存在易团聚、难回收等缺点,选用白云母为载体,采用溶胶-凝胶法制备了白云母,纳米TiO2复合光催化材料．用制备的材料在紫外光照射条件下处理直接铜络合偶氮染料废水．结果表明：500℃焙烧的复合材料对废水的光催化脱色率达到61％以上．该复合材料有望在废水处理、环保涂料领域得到应用．     

介孔二氧化硅制备和pH响应型纳米容器应用综合研究型实验

设计了介孔二氧化硅的制备、表征及pH响应型纳米容器应用综合研究型实验。该实验包括溶胶-凝胶法制备二氧化硅、表面形貌和介孔结构分析、pH响应性能测量等实验内容,形象展示了二氧化硅生长、独特结构和优异响应性能之间的内在联系,让学生对多孔材料特征有整体的认识。该实验选题新颖,实验内容涵盖材料学、化学、纳米容器等知识点。教学实践表明,该综合研究实验全面培养了学生的综合素质和创新能力。     

纳米金属纤维的湿化学法制备技术

纳米金属纤维在微波吸收材料、纤维增强材料、过滤材料等领域得到了广泛的应用。评述了金属阳离子还原法、水热法、模板辅助法、沉淀法、有机凝胶法和静电纺丝法等湿化学法制备纳米金属纤维的原理、工艺与技术特点,讨论了湿化学技术制备纳米金属纤维的优缺点及研究趋势。     

气凝胶的非超临界干燥制备技术

气凝胶一般通过溶胶－凝胶过程和超临界干燥这两个步骤制取。由于超临界干燥所需设备要求较高，控制条件苛刻，制备周期很长，因而大大增加了制备气凝胶的困难。本文提出以非超临界干燥技术来替代超临界干燥过程的方法，阐述实现非超临界干燥制备气凝胶的几种措施，并介绍实施非超临界干燥技术制备SiO2气凝胶所得到的结果。     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help?     

只要努力,不要后悔

There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love.     

浅谈移民问题

Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject.     

Sister Carrie, an Adherent of Desires

Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities.     

Improvement of one-cycle controller by use of proportional integral differential controller

1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec…     

库克斯顿城堡

城堡, 是欧洲典型的建筑之一, 每个城堡都有一个美丽的传说或是一段历史。从本期开始, 我们将推出“城堡之旅”, 带各位读者去浏览、观赏欧洲各地的城堡, 开始一段文化与历史的旅途!     

胡主席在印度,我却在中国

Today, Sunday morning, I sit thinking and typing at my computer. My thoughts are in my homeland, India and my body is in China. The body is here and mind there for a good reason. Mr. Hu is president and I am resident and both are in each other's countries (what a difference the absence of one small letter makes!). Mr. Hu will return in a few days and I will stay on longer.