First-principles study of electrical structures and optical properties of Ag or Au doped MgF2 crystal

The geometric structure, electronic and optical properties of MgF₂ crystal mixed with Ag, Au are obtained by adopting the first-principles calculation of plane wave ultra-soft pseudo-potential technology based upon the density function theory (DFT). The calculation results show that the doping of Ag and Au diminishes of the MgF₂ system and the occurrence of half-metallic properties with a greater influence of Au than Ag. In addition, the refractive index and absorption coefficient of the MgF₂ system are enhanced because of the doping. The modulation action on the refractive index of MgF₂ indicates potential application of the forbidden bandwidth doping in optical devices.     

铑(Ⅲ)-偶氮氯膦pA-溴酸钾褪色反应催化光度法测定痕量铑

报道了以铑（Ⅲ）催化溴酸钾氧化偶氮氯膦pA为基础测定痕量铑的催化光度分析法,建立了一种在水相中直接测定痕量铑（Ⅲ）的新方法。铑（Ⅲ）含量在5~30μg/L范围内符合比耳定律,检出限为5μg/L,本法用于铂-铑催化剂中铑的测定,结果满意。     

硫酸钡微晶改性毛细管柱的制备及其分离性能的研究（Ⅰ）

本文提出利用硫酸钡微晶对玻璃毛细管内表面进行改性,成功地将中、强极性固定液涂溃在这种改性表面上,制备出高效毛细管色谱柱。文中较详细地给出了硫酸钡微晶的制备方法以及微晶层的沉积方法,并对这种毛细管色谱柱的性能进行了考察。     

Azacrown ethers containing oximic and Schiff base sidearms - potential heteronuclear metal ion receptors

A simple synthetic pathway for the preparation of oxime- and Schiff base-containing aza- and diazacrown ethers is reported. N-Methoxymethyl-substituted aza-15-crown-5 and aza-18-crown-6 as well as N,N′-bis(methoxymethyl)-substituted diaza-18-crown-6 were treated with 5-bromosalicylaldehyde to produce the N-(2′-hydroxy-3′-carbonyl-5′-bromobenzyl)-substituted aza-15-crown-5 (8), aza-18-crown-6 (9) and N,N′-bis(2′-hydroxy-3′-carbonyl-5′-bromobenzyl)-substituted diaza-18-crown-6 (10) compounds. Compounds 8 and 10 were treated with hydroxylamine to give oxime-substituted ligands 12 and 13. A series of bis-Schiff base-containing diaza-18-crown-6 ligands were prepared by reacting 10 with 2-hydroxyaniline (to form 14), 5-nitro-2-hydroxyaniline (15), 2-aminopyridine (16), 2-hydrazinopyridine (17) and N-aminomorpholine (18). Compounds 12–18 are potential complexing agents for simultaneous binding of soft transition and hard alkali or alkaline earth metal ions in one molecule. These new oxime- and Schiff base-containing ligands interacted strongly with Na⁺ and K⁺ in methanol. The interaction of the aromatic portions of 9, 10, and 12–15 with transition metal ions was shown by the UV spectra of the metal ion complexes in 50% aqueous DMF. The X-ray structure of 10 is reported.     

Recognition and Site‐Selective Transformation of Monosaccharides by Using Copper(II) Catalysis

We demonstrate copper(II)‐catalyzed acylation and tosylation of monosaccharides. Various carbohydrate derivatives, including glucopyranosides and ribofuranosides, are obtained in high yields and regioselectivities. Using this versatile strategy, the site of acylation can be switched by choice of ligand. Preliminary mechanistic studies support nucleophilic addition of a copper–sugar complex to the acyl chloride to be turnover limiting.     

Synthesis and Properties of Semicrystalline Copolyimides Based on 4,4′-Diaminodiphenylether and 1,3-Bis(4-aminophenoxy) Benzene

Copolyimides were prepared from 4,4′-diaminodiphenylether (4,4′-ODA), 1,3-bis(4-aminophenoxy) benzene (TPER), and pyromellitic dianhydride (PMDA) through a three-step imidization process with different monomer compositions. The copolymerization disrupted the molecular regularity and decreased the intermolecular interaction of the polyimide chains. The X-ray diffraction (XRD) results indicated the prepared copolyimides showed the same semicrystalline character, but had various crystallinity and crystal forms. The copolymerization also changed the crystal morphologies of the polyimides. With increasing TPER ratio, the copolyimides started to form spherulites and hedrites, which then tended to grow more perfectly as the TPER ratio was further increased. The solubility of the copolyimides and their dependence on the crystallnity and the chain flexibility was investigated. These copolyimides exhibited excellent thermal and thermo-oxidative stability.     

Structural characterization and high‐temperature compressive creep of PTFE‐based composites filled with inorganic nanoparticles

The PTFE‐based nanocomposites with various contents of inorganic nanoparticles (n‐AlN and n‐Si₃N₄) were prepared by cold compaction followed by free sintering. The results of scanning electron microscopy, differential scanning calorimetry, and X‐ray diffraction show that PTFE spherulite formed in the nanocomposites. When 2 wt% inorganic nanoparticles were added into the PTFE matrix, the crystallinity increased from 34.3% to 42.1% and 43.2%, respectively. Moreover, the interplanar distances for each crystal plane were enlarged and the grain sizes were smaller than that of pure PTFE. In addition, the mechanical and high‐temperature compressive creep properties were investigated. The results indicate that the introduction of inorganic nanoparticles largely increased the high‐temperature compressive creep resistance, and the maximal reduction of percentage of creep strain was up to 68%. The tensile strengths of the nanocomposites increased with increasing filler content when it was no more than 2%, and then decreased with the further increase of the filler content, whereas the elongations at break showed a reverse tendency. Copyright © 2011 John Wiley & Sons, Ltd.     

ATP-Responsive Nanoparticles Covered with Biomolecular Machine “Chaperonin GroEL”

Herein, we report an ATP-responsive nanoparticle (^GroELNP) whose surface is fully covered with the biomolecular machine “chaperonin protein GroEL”. ^GroELNP was synthesized by DNA hybridization between a gold NP with DNA strands on its surface and GroEL carrying complementary DNA strands at its apical domains. The unique structure of ^GroELNP was visualized by transmission electron microscopy including under cryogenic conditions. The immobilized GroEL units retain their machine-like function and enable ^GroELNP to capture denatured green fluorescent protein and release it in response to ATP. Interestingly, the ATPase activity of ^GroELNP per GroEL was 4.8 and 4.0 times greater than those of precursor ^cysGroEL and its DNA-functionalized analogue, respectively. Finally, we confirmed that ^GroELNP could be iteratively extended to double-layered NP.