纳米科技进展精读论文题目

玻璃化保存是低温保存的发展方向，唯有玻璃化技术才有可能突破大器官的低温保存。降温速率是实现玻璃化保存的关键因素之一，提高降温速率的方法主要有以下两种：一是采用小体积的样品以及增加物体内外的温差，二是减小物体内部的热阻。很多研究已经在物质外部的温度环境方面做了大量的工作，并取得了显著成果，但对于大体积的生物样品，降温速率主要取决于内部的传热传质特性，受外界环境影响是次要的。目前对第二种方法的研究还较少。 纳米科技的发展使得通过改变溶液内部的结构来强化传热成为一种可能。本课题围绕纳米低温保护剂的制备与悬浮稳定研究、羟基磷灰石（HA）纳米微粒对低温保护剂PVP的比热容、密度和导热系数的影响等几个方面的内容，研究了纳米微粒对低温保护剂降温速率的影响。主要内容如下： 纳米低温保护剂的制备及悬浮稳定性研究。采用纳米粒子与液体直接混合、超声震荡等方法，制备几种不同类型的纳米低温保护剂，获得悬浮稳定的纳米低温保护剂。实验结果表明，在超声功率150W-450W时，震荡小时后获得了均匀稳定的纳米低温保护剂；配制的纳米低温保护剂在2天内没有明显的团聚沉淀现象；超声震荡对纳米微粒的粒径（20nm）没有显著性影响。 用差示扫描量热仪（DSC）测量了不同浓度、不同粒径纳米低温保护剂的玻璃化转变温度和反玻璃化转变温度。结果表明：浓度为50%-60%（w/w）的HA-PVP纳米低温保护剂，玻璃化转变温度比没有加入纳米的PVP低温保护剂低4-7℃，并且玻璃化温度随着纳米微粒质量浓度的增加而逐渐降低。低粘度HA-EG溶液结晶焓数据表明，溶液结晶量受低温保护剂种类和纳米微粒浓度的影响。 PVP纳米低温保护剂在玻璃化过程中的比热受纳米微粒浓度的影响，纳米微粒的浓度越大，比热越小。纳米低温保护剂在降温过程中的密度随纳米微粒质量浓度的变化为指数关系变化，在质量浓度为左右时，低温保护剂的体积几乎不发生变化，这个质量浓度是纳米低温保护剂在该降温速率下实现玻璃化的转折点。 利用瞬态热线装置，测量了不同种类、不同体积浓度的纳米低温保护剂的导热系数。实验结果表明，在保护剂中添加纳米微粒显著增加了悬浮液的导热系数，纳米低温保护剂的导热系数随纳米微粒体积份额的增加呈线性增大。 研究影响热扩散率（a=λ/(ρc)）的三个参数（导热系数、密度和比热），发现含有纳米微粒的低温保护剂导热系数比不含有纳米微粒的大，而比热和密度在玻璃化过程中都因纳米微粒的存在而变小，所以加入的纳米微粒可以增大低温保护剂的热扩散系数，进而提高低温保护剂在降温过程中的降温速率。Abstract Cryopreservation by freezing fails to provide effective protection to tissues or organs because of the destructive effect of extracellular ice formation. Vitrification was developed as an alternative to freezing to solve the problems of human organ cryopreservation. Vitrification is essentially the solidification of a supercooled liquid by adjusting the composition, cooling rate, and sometimes pressure to avoid crystallization. Relatively high concentrations of cryoprotective agents (CPAs) are required to achieve a glassy state and relatively fast cooling and warming rates are required to avoid damage associated with ice crystallization. These rapid cooling rates may not be possible to achieve as the size of biomaterials become larger. Modern nanotechnology provides new challenges and opportuneities for thermo-science. Nano-CPAs are a new type of heat transfer carriers by suspending nanoscaled metallicor nonmetallic particles in base CAPs. Nano-CPAs are expected to exhibit heat transfer properties superior to those of conventional heat transfer purpose of this paper is to study experimentally and theoretically the enhancement of nanoparticles to the heat transfer of nano-CAPs, as following: 1. Preparation and stability of nano-CPAs. This paper presents a preparation method of nano-CPAs by directly mixing nanoscaled powders into base CPAs fluids. Some auxiliary dispersants are necessary to obtain the even distributed and stabilized suspensions. With this method, several types of CPAs of different volume fraction have been prepared. The stability and evenness of suspensions were evaluated using the TEM photographs. Some factors influencing the stability and evenness of nano-CPAs, such as the property of base CPAs fluid, the dimension and the property of nanoparticles, are discussed. 2. The glass transition temperature，and the nucleation temperature of the PVP based nano-CPAs are measured by differential scanning calorimeter. The concentration of PVP are 50%, 55% and 60% respectively. Various amount of nanoparticles were added into the PVP solutions to study the effect of nanoparticles on the glass transition temperature of nano-CPAs. CPAs, with or without HA nanoparticles, are scanned by DSC in the temperature range of 30℃ to -65℃ to determine the heat caoacity of CPAs. The results show that the heat capacity of CPAs with HA is smaller than that without nanoparticles. 3. Nano-CPAs have better heat transfer performance compared to conventional heat transfer fluids. One of the reasons is that the suspended nanoparticles remarkably increase the thermal conductivity of the nanofluids. In this study, the thermal conductivities of some nano-CPAs are measured by using the transient hot wire instrument. The effects of the volume fraction,dimensions,properties of the nanoparticles and temperature on the thermal conductivity of nano-CPAs are discussed. The mechanism that nano-CPAs increase the thermal conductivity of nano-CPAs is discussed. Based on the above results, it is concluded that the specific heat and density of nano-CPAs are lowered by the nanopaiticles during the cooling process. The thermal diffusivity (a=λ/(ρc)）) is higher for PVP solutions with nanoparticles compared to that without nanoparticles. The conclusion was drawn that the nanoparticles can improve the cooling rate of nano-CPAs during the cooling process.

1. 溶胶-凝胶法制备纳米材料研究进展2. 电子显微镜在纳米材料研究中的应用3. SPM与纳米材料组装研究进展4. 稀土发光纳米材料的研究进展5. II-VI族纳米材料研究进展6. 纳米材料在生命科学中的应用研究进展7. III-V族纳米材料研究进展8. 仿生技术与纳米材料研究进展9. 纳米机器人研究进展10. 纳米技术与国防安全11. 纳米科技中的伦理学研究进展12. 纳米技术与军事现代化研究进展13. 水热法在纳米科技中的应用14. 激光拉曼光谱在纳米材料分析中的研究进展15. 纳米材料粒度分析研究进展16. 纳米蓄能材料研究进展17. 锂离子电池纳米材料研究进展18. 染料敏化太阳能电池用纳米材料研究进展19. 纳米科技人才的培养与需求现状

纳米材料的研究内容及进展一、① 天然纳米材料， ② 纳米磁性材料 ，③ 纳米陶瓷材料 ，④ 纳米传感器 ，⑤ 纳米倾斜功能材料，⑥ 纳米半导体材料，⑦ 纳米催化材料，⑧ 医疗上的应用 ，⑨ 纳米计算机二、进展