团簇淀积纳米结构薄膜的计算机模拟

对团簇的淀积方式作了简介。着重对团簇的淀积过程进行了计算机模拟,从中得出了淀积的尺寸分布与团簇在衬底上的徙动长度有关,而团簇的聚合长大存在一临界尺寸。并给出低能Ｐｂ团簇在碳膜表面的徙动长度和聚合的临界尺寸。     

La_(0.7-x)Gd_xSr_(0.3)MnO_3(x=0.20,0.30,0.40,0.50)的TCR研究(英文)

研究了La位Gd掺杂对La0.7-xGdxSr0.3MnO3(x=0.20,0.30,0.40,0.50)体系的电阻温度系数(TCR)的影响.实验结果表明:Gd掺杂将引起电阻率曲线的急剧变化,导致出现大的TCR;而且随Gd掺杂的增加,TCR在x=0.30出现峰值,然后随掺杂量增加逐步降低.体系出现大的TCR,来源于Gd掺杂引起的额外磁性耦合.     

The “Problem” of Experience in Mathematics Teaching

Prior research has established that teachers' use of curriculum materials is affected by a range of factors, such as teachers' conceptions of mathematics teaching, and the nature and extent of their teaching experience. What is less clear, and far less examined, in prior research is the role that the teacher guide (TG) may play in mediating the influence of these and other factors on teachers' decisions and actions. Accordingly, this study examines how two 6th grade teachers use the TG from Connected Mathematics Project as a resource in making planning and enactment decisions, and factors associated with patterns of TG use. Through cross‐case analysis, the author found that these teachers seemed to draw largely from their previous experiences and their own conceptions of mathematics teaching and learning when making planning and enactment decisions related to mathematical tasks, and not particularly from the TG. For example, when faced with certain planning and instructional challenges, such as students struggling with the content, teachers tended to rely on their particular conceptions of mathematics teaching to address these challenges. Despite the fact that the TG provided suggestions for teachers as to how address such challenges, it was not extensively used as a resource by the teachers in this study in their planning and enactment of lessons.     

Preparation of Silver Nanoshells on Silica Particles by a Simple Two-step Process

A simple two-step method was developed to prepare silver nanoshells coated on silica paticles. The method involves two steps: concentration of reaction precursor (AgNO3) on particle surfaces and subsequent reduction by formaldehyde. The obtained composite particles were characterized by TEM, ED, and SEM-EDS measurements. The results show that the silver nanoshell is coated on silica particle surface in the form of a polycrystalline (cubic structure) layer with average thickness of 20 nm and weight percentage of 1.9%.     

Recent advances in spin transport in organic semiconductors

The spin relaxation time is long in organic semiconductors because of the weak spin-orbit and hyperfine interactions,leading to intensive study on spin transport in organic semiconductors.The rapid progress towards utilizing spin degree of freedom in organic electronic devices is occurring.While the spin injection,transport and detection in organic semiconductors are demonstrated,the fundamental physics of these phenomena remains unclear.This paper highlights recent progress that has been made,focusing primarily on present experimental work.     

Synthesis of N~(11)-anchoring biotinylated artemisinin derivatives and their preliminary biological assessment

Unique endoperoxide moiety of artemisinin and its derivatives has been considered the functionality exhibiting highly potent antimalarial and anticancer activities.To investigate the mechanisms of their biological actions,development of suitable molecular probes including biotinylated derivatives is of extreme significance.The synthesis and preliminary biological assessment of four new biotinylated artemisinin derivatives have been reported in this work.     

Synthesis of thiol-functionalized TiO_2 nanocomposite and photocatalytic degradation for PAH under visible light irradiation

In this paper,a thiol-functionalized nanophotocatalyst MPTES/TiO_2 was first synthesized by one-pot method using P123 as a template.X-ray diffraction confirms the complete anatase crystalline of thiol-functionalized TiO_2,N_2 adsorption-desorption isotherm demonstrated that these materials possess high surface area and mesoporous structure.The results of XPS show that MPTES has been successfully polymerized in mesoporous structured TiO_2.The photodegradation of phenanthrene(PHE) was investigated under vi...     

Torsional response and stiffening of individual multiwalled carbon nanotubes

We report on the characterization of torsional oscillators which use multiwalled carbon nanotubes as the spring elements. Through atomic-force-microscope force-distance measurements we are able to apply torsional strains to the nanotubes and measure their torsional spring constants, and estimate their effective shear moduli. The data show that the nanotubes are stiffened by repeated flexing. We speculate that changes in the intershell mechanical coupling are responsible for the stiffening.     

A Highly Tunable Silicone-Based Magnetic Elastomer with Nanoscale Homogeneity

Magnetic elastomers have been widely pursued for sensing and actuation applications. Silicone-based magnetic elastomers have a number of advantages over other materials such as hydrogels, but aggregation of magnetic nanoparticles within silicones is difficult to prevent. Aggregation inherently limits the minimum size of fabricated structures and leads to non-uniform response from structure to structure. We have developed a novel material that is a complex of a silicone polymer (polydimethylsiloxane-co-aminopropylmethylsiloxane) adsorbed onto the surface of magnetite (γ-Fe₂O₃) nanoparticles 7-10 nm in diameter. The material is homogenous at very small length scales (<100 nm) and can be crosslinked to form a flexible magnetic material, which is ideally suited for the fabrication of micro- to nanoscale magnetic actuators. The loading fraction of magnetic nanoparticles in the composite can be varied smoothly from 0 to 50 wt% without loss of homogeneity, providing a simple mechanism for tuning actuator response. We evaluate the material properties of the composite across a range of nanoparticle loading, and demonstrate a magnetic-field-induced increase in compressive modulus as high as 300%. Furthermore, we implement a strategy for predicting the optimal nanoparticle loading for magnetic actuation applications, and show that our predictions correlate well with experimental findings.