Preparation and Characterization of Fe3O4 Magnetic Nano-particles by 60Co γ-ray Irradiation

By using a new method, 60C0 γ-ray irradiation, Fe3O4 magnetic nano-particles were successfully synthesized at room temperature under ambient pressure. The structure, morphology and magnetic properties of these nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and vibrating sample magnetometer (VSM), respectively. The radiation formation mechanism was also discussed. The results show that the absorbed dose can greatly influence the structure, morphology and magnetic properties of the products. XRD and TEM studies show that the product prepared by γ-ray irradiation (10 kGy) is pure FesO4 phase and the mean diameter of these nano-particles is about 21 nm. The Fe3O4 nano-particles synthesized by γ-ray irradiation (10 kGy) are mainly in small cubic shape and the size uniformity of these particles is good.     

Cu/Al复合材料的制备及其对RDX热分解性能的影响

为了改善铝粉的表面氧化,提高其对含能材料热分解的催化作用,以电爆炸铝粉和二水合氯化铜(CuCl_2·2H_2O)为原料,利用置换反应法,实现了纳米铜粒子在铝粉表面的快速沉积,制备了包覆均匀的Cu/Al复合材料。利用扫描电镜(SEM)、透射电镜(TEM)、X?射线粉末衍射(XRD)、电子能谱(EDS)等对其结构和形貌进行了表征。在不同的升温速率下测试了Cu/Al复合材料与黑索今(RDX)(质量比1∶5)混合物的DSC曲线。计算了该混合物热分解反应的动力学参数。结果表明,电爆炸铝粉表面的氧化层通过氟化铵的刻蚀作用被剥离,复合材料含有单质铝和单质铜晶相,无氧化铜及氧化铝晶相,纳米级铜颗粒均匀包覆在铝粉表面,复合材料粒径为200～500 nm。加入Cu/Al复合材料后,RDX的初始分解温度和分解峰温分别降低8.51℃和26.43℃,分解热提高296 J·g~(-1),热分解活化能降低19.19 kJ·mol~(-1),表明Cu/Al复合材料可促进RDX的热分解行为。     

一种具有片上译码/放大功能的微阵列电路及其与生物纳米系统的集成

提出了一种用SMIC 0.18μm CMOS混合信号工艺实现的全集成CMOS微阵列生物芯片,并成功地实现了其与一种新的生物纳米系统的集成. 该电路实现了19μm×19μm电极的4×4 (16单元）阵列,反相电极,电流模式放大器,译码电路,以及逻辑控制电路的单片集成,并能够提供-1.6~1.6V的组装电压,8bit的电位分辨率及39.8dB的电流增益,电源电压为1.8V,而失调和噪声电流分别为5.9nA和25.3pArms. 在实验中,利用该电路实现了对30nm聚乙烯醇包裹的磁性粒子的片上选择性组装,并对实验结果进行了讨论,从而验证了该电路的正确性和该集成方法的可行性.     

碳纳米管场发射冷阴极的低温制备及场发射性能

利用纳米银的低温熔接性和良好导电性,研究了以纳米银取代传统的有机粘结剂和导电银浆制备CNTs场发射冷阴极的新工艺.将CNTs、纳米银、粘性松油醇和有机溶剂混合研磨后涂敷在镀Cu玻璃基片上,250℃烧结30min后,纳米银颗粒之间互相熔接,将周围的CNTs粘结成为整体膜,形成了表面平整、导电性和场发射性能良好的CNTs阴极.测量了不同纳米银掺入量的CNTs阴极的场发射性能,结果表明:当CNTs:Ag质量比率为1:1时,CNTs阴极具有最好的场发射性能,阈值电场为4.9V/μm,当电场强度为5.7V/μm时,场发射电流密度为41mA/cm2.纳米银比例过大,烧结后CNTs被熔接的银膜覆盖,高电压时场发射电流明显下降,而纳米银掺入量太少则会导致CNTs阴极的附着力和导电性变差.     

超声分散技术在制备小颗粒(Y,Gd)BO_3∶Eu~(3+)粉体中的应用

采用共沉淀法结合超声分散技术制备亚微米级红色荧光粉(Y,Gd)BO3∶Eu3+,研究了超声时间对离子混合及沉淀过程的影响,以及进而对粉体性能的影响。采用红外光谱(IR)、扫描电子显微镜(SEM)、粉末X射线衍射(XRD)、PDP真空紫外荧光粉测试系统对荧光粉的组成、结构与光学性能等进行表征,结果表明:(Y,Gd)BO3∶Eu3+中[BO3]基团中B原子以四配位为主,同时混有三配位,主体基质YBO3以六方碳钙石结构存在,空间群为P63/mmc(194),晶胞参数a=3.778,c=8.814;在离子混合和沉淀过程中经过超声分散制备的粉体与未经超声分散制备的粉体相比较,相对发光强度提高,色坐标红移(x=0.6392,y=0.3604→x=0.6422,y=0.3575),红橙比(626nm/592nm)提高12%,粒径细小,颗粒形貌均匀,分散性良好。     

试论我国西部盐湖镁资源的高度利用对策

受技术经济条件限制 ,我国西部盐湖中蕴藏的大量镁资源至今尚未得到有效利用。研究开发高新镁盐产品 (如高纯微细氢氧化镁阻燃剂、碱式硫酸镁晶须、硼酸镁晶须、高纯氧化镁、纳米氧化镁等 )是高度利用西部盐湖镁资源的重要发展方向     

Impact of dietary fibers on the properties and proteolytic digestibility of lactoferrin nano-particles

The application and development of biopolymer-based particulate delivery systems is receiving considerable attention from scientists and manufacturers seeking to engineer healthier and safer foods. Present work focused on the fabrication and proteolysis of bovine lactoferrin nano-particles onto which pectins, alginate and carrageenan were electrostatically deposited. DLS, CD and AFM were used to ascertain the formation of spherical structures with varying zeta potentials and modified protein folding. SDS-PAGE analyses of samples collected during simulated human gastro-duodenal digestion revealed that in the case of high and low methoxy pectin particle zeta potential values (−35.4 mV and −50.3 mV respectively) were found to be inversely linked to lactoferrin digestion rate. Moreover, the electrostatic binding of food grade iota-carrageenan onto lactoferrin nano-particles was found to yield highly charged particles (zeta = −69.2 mV) with low surface roughness and to enable a proportion of the lactoferrin to resist 1 h of simulated gastric digestion. Overall, these findings suggest that electrostatic biopolymer interactions may modulate protein digestion and possibly facilitate controlled protein delivery to the upper gastrointestinal tract or have implications to protein nutritional value.     

Role of the Initial Formation of the Iron Nano-Particles in the Multi-Walled Carbon Nanotubes Growth Process

Careful preparation of the iron nano-particle catalyst for carbon nanotubes (CNTs) fabrication has crucial importance for initial growth of multi-wall carbon-nanotubes (MWCNTs). Thin iron layer was thermally deposited in a high vacuum onto the surface of the SiO2/Si wafer at about 300 K. The sample was heated up to 700℃ in a hydrogen atmosphere, and then the sample was heated once again at750℃ in ethylene atmosphere. After hydrogen treatment continuous Fe layer was changed into many well separated Fe nano-peaks. AFM, SEM and HR-TEM studies of deposited MWCNTs allow us to propose a growth mechanism for long, straight MWCNTs.     

采用纳米Al203和碳纳米管颗粒强化CO2吸收的理论及实验研究（英文）

The influence of nano-particles on CO2 absorption was studied experimentally in a stirred thermostatic reactor. Nano-A1203 and carbon nanotube （CNT） particles which showed different hydrophobic properties were chosen for the investigation. The experimental results were compared with that of micron-size activated carbon （AC） and Al2O3 particles. From the results, no enhancement by micron-size A1203 was found, and with the increase of A1203 concentration, the enhancement factor decreased. However, nano-Al203 showed a weak enlaancement tor me COz absorption. AC and CNT particles all intensified the gas-liquid mass transfer effectively, yet the trend of the enhancement factor with stirring speed for the two particles was different. With increasing stirring speed, the enhancement factor of AC particles was decreased, wl＇iereas in CNT suspensions it was increased. The experimental phenomena demonstrated a difference in enhancement mechanism for different size particles. For nano-particles, besides the influence of adsorbability and hydrophobicity, the micro-convection caused by Brownian motion should be also taken into account. Considering the micro-convection effect, a theoretical model was developed to shed light on the absorption enhancement bv nano-oarticles.     

水解-水热法低温制备金红石型TiO2纳米颗粒研究

以硫酸钛为原料,通过水解-水热反应,在较低温度下制备出金红石型TiO2纳米颗粒.利用XRD和TEM研究了其结晶度、晶型和粒度情况和水热反应温度、保温时间、升温速度以及前驱物的pH值之间的关系,比较了常规条件和水热条件下反应产物的状况,并探讨了水热条件下晶相转化机理,以及控制晶相的关键因素。