水热纳米浇筑HNTs模板法制备碳纳米棒

以埃洛石纳米管（HNTs）为模板和聚乙烯醇（PVA）为碳源,采用水热纳米浇筑法成功制备出碳纳米棒。方法涉及3步,即在HNTs中浇筑PVA,碳化和模板移除。采用一系列表征手段如XRD、FT-IR、SEM、TEM、Raman、XPS、SAED和N₂吸附-脱附等表征碳纳米棒的形成和结构。具有一维棒状结构的碳纳米棒具有高的比表面积（409 m²·g^-1）和典型的介孔特征。     

Thermal spin transfer in Fe-MgO-Fe tunnel junctions

We compute thermal spin transfer (TST) torques in Fe-MgO-Fe tunnel junctions using a first principles wave-function-matching method. At room temperature, the TST in a junction with 3 MgO monolayers amounts to 10(-7) J/m(2)/K, which is estimated to cause magnetization reversal for temperature differences over the barrier of the order of 10 K. The large TST can be explained by multiple scattering between interface states through ultrathin barriers. The angular dependence of the TST can be very skewed, possibly leading to thermally induced high-frequency generation.     

Effect of surface ethoxy groups on photoactivity of TiO2 nanocrystals

TiO₂ nanocrystals modified by ethoxy groups were prepared by a facile nonhydrolytic solvothermal method and characterized by XRD, TEM, TG-DTA and XPS, which showed an enhanced visible-light photocatalytic activity on the degradation of Rhodamine B compared with TiO₂ modified by benzyloxy groups and the “naked” TiO₂. The adsorption and degradation pathway of Rhodamine B on TiO₂ modified by ethoxy groups were also investigated. The zeta-potential (ζ) results showed that the TiO₂ modified by ethoxy groups had high negative surface charge, which incited the positive -N(Et)₂ group of RhB absorbing on the TiO₂ surface and preferably led the N-dealkylation pathway under visible light irradiation.     

建立微尺度蒸发冷凝的通用准则

蒸发冷却模式以及微换热器,是最具有潜力的冷却高热流密度电子器件的方法之一。总结和研究微尺度蒸发冷凝相变机理,是本文研究目的。我们在参阅大量文献和提取大量精确数据的基础上,发现了新的区分常规通道与微通道的临界准则Bo×Re1^0.5=200;在此基础上,我们归纳出了新的预测微通道压降、传热系数和临界热流量的关联式,与以前...     

Magnetism in Cr doped ZnO: Density-functional theory studies

We investigate the magnetism in wurtzite and zinc-blende Zn_0.875Cr_0.125O (wz- and zb-Zn_0.875Cr_0.125O) using the density-functional theory calculations. We demonstrate that the delta-doping structures are more energetically favorable than the homogeneous-doping ones. The delta-doping structure of zb-Zn_0.875Cr_0.125O shows robust ground state ferromagnetism (FM) with ferromagnetic stabilization energy of 575 meV/Cr-Cr pair, while delta-doping structure of wz-Zn_0.875Cr_0.125O shows weak ground state anti-FM. We discuss the magnetic coupling in Zn_1−xCr_xO, and the origin of FM in zb-Zn_1−xCr_xO using a crystal field model. Finally, we anticipate the potential spintronics applications of the zb-Zn_1−xCr_xO.     

Low‐Temperature Synthesis of Crystalline Inorganic/Metallic Nanocrystal‐Halloysite Composite Nanotubes

We have demonstrated a facile approach for the low‐temperature synthesis of crystalline inorganic/metallic nanocrystal‐halloysite composite nanotubes by employing the bulk controlled synthesis of inorganic/metallic nanocrystals on halloysite nanotubes. The halloysite clay nanotubes can adsorb the target precursor and induce inorganic/metallic nanocrystals to grow in situ. The crystalline phase and morphology of the composite clay nanotubes is tunable. By simply tuning the acidity of the titania sol, the crystalline titania‐clay nanotubes with tunable crystalline phases of anatase, a mixture of anatase and rutile or rutile are achieved. The approach is general and has been extended to synthesize the representative perovskite oxide (barium and strontium titanate)‐halloysite composite nanotubes. Metallic nickel nanocrystal can also be grown on the surface of halloysite nanotubes at low temperature. The traditional thermal treatment for crystallite transformation is not required, thus intact contour of halloysite nanotubes and the crystallinity structure of halloysite nanotubes can be guaranteed. The combined properties from inorganic/metallic nanocrystal (high refractive index, high dielectric constant and catalytic ability) and the halloysite clay nanotubes are promising for applications such as photonic crystals, high‐k‐gate dielectrics, photocatalysis and purification.     

中国工业化发展态势分析:1981～2001

本文利用时序全局主成分分析法对1981～2001年中国的工业化发展作了动态描绘,结果表明,1981～2001年中国的工业化发展处于整体攀升并伴有小幅波动态势。动态轨迹与客观实际能较好的吻合,可为中国工业化进一步健康发展提供参考依据。     

离子色谱法测定电厂凝水处理模拟系统高纯水中的全铁

研究了用离子色谱法测定电厂凝水处理系统中高纯水中全铁的方法，用过硫酸铵将水样中的铁全部转化成Fe^3 ，再用浓缩柱浓缩样品，离子色谱法分析Fe^3 ，得到全铁的含量，检出限为1μg/L。     

CHARACTERIZATION OF SOME SCHIFF BASES OF HETEROCYCLIC COMPOUNDS AND THEIR TRANSITION METAL COMPLEXES

Some new Schiff bases were synthesized by the condensation ofequimolar quantities of salicylaldehyde and 2-amino-5-phenylazo-pyridine orits derivatives in dry benzene(1):Metal complexes of the type ML_2and M'L_3where M=Cu~(2+),Co~(2+),Ni~(2+),Mn~(2+)Pd~(2+),M'=Fe~(3+)and L=different newly synthesizedmonobasic Schiff bases were prepared in absolute ethanolic medium(2)andcharacterized by elementary analysis,conductance measurements,infraredspectra,electronic spectra,magnetic moments studies.     

Organocatalytic Dynamic Kinetic Resolution Enabled Asymmetric Synthesis of Phosphorus-Containing Chiral Helicenes

The catalytic asymmetric synthesis of phosphorus-containing helicenes remains a formidable challenge, presumably due to the lack of rational design of substrates, right choice of reactions together with highly effective catalysis systems. Herein, we disclosed an efficient and practical DKR-involving (dynamic kinetic resolution) cascade strategy toward synthesizing a novel family of phosphorus-installing helicenes by peptide-mimic phosphonium salt (PPS) catalysis. The sequential process of PPS-catalyzed phospha-Michael attack and copper salt-facilitated aromatization led to the formation of unprecedented phosphorus-containing oxa[5]helicene scaffolds. A wide variety of substrates bearing an assortment of functional groups were compatible with this protocol, furnishing the expected helical compounds in high yields and excellent stereoselectivities. Additionally, the helical products could be conveniently elaborated to promising phosphine ligands with perfectly retained helical chirality, which turned out to be highly efficient chiral ligands in transition metal-catalyzed reactions. These findings not only expand the current library of phosphorus-containing helicenes but also offer insights to explore other challenging scaffolds with molecular chirality.