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41.
Dr. Zewei Quan Loriana Valentin‐Bromberg Welley Siu Loc Prof. Jiye Fang 《化学:亚洲杂志》2011,6(5):1126-1136
This review focuses on recent developments in the self‐assembly of lead chalcogenide nanocrystals into two‐ and three‐dimensional superstructures. Self‐assembly is categorized by the shapes of building blocks, including nanospheres, nanocubes, nano‐octahedra, and nanostars. In the section on nanospheres, rapid assemblies of lead chalcogenide‐based multicomponent nanocrystals with additional components, such as semiconductors, noble metals, and magnetic nanocrystals, are further highlighted. In situ self‐assembly of lead chalcogenide nanocrystals into one‐dimensional nanostructures at elevated temperatures is also covered. Each section of this paper highlights examples extracted from recent publications. Finally, relatively novel properties and applications arising from lead chalcogenide superlattices as typical examples are also discussed. 相似文献
42.
The blue organic dye, 2,6-dichloroindophenol (DCIP), was immobilized on PEGylated Merrifield resin after a chlorination step followed by a nucleophilic substitution reaction, using microwave-assisted methodology. The final product was a blue pigmented resin that can be reversibly reduced by ascorbic acid and changes color from blue to light yellow. Structural elucidation of this immobilized indicator was confirmed through FTIR and elemental analyses. 相似文献
43.
L.W. Yang X.L. Wu G.S. Huang T. Qiu Y.M. Yang G.G. Siu 《Applied Physics A: Materials Science & Processing》2005,81(5):929-931
Highly aligned Mn-doped Zn2SiO4 nanorods were fabricated by using a modified vapor-phase evaporation method. Their microstructure and chemical bond configurations were investigated with the help of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared absorption spectroscopy, and X-ray photoelectron spectroscopy. The formation process of the Mn-doped Zn2SiO4 nanorods can be elucidated on the basis of a self-catalytic vapor–liquid–solid growth mechanism in which Mn chloride hydrate acts as the catalyst and impurity source. Photoluminescence measurements revealed that an intensive green luminescence peak appears at 523 nm, which corresponds to the electronic transition 4T1(4G)→6A1(6S) of Mn2+ ions. Our experimental results provide a useful approach to directly fabricate Si-based nanoscale light-emitting materials using ZnO–Zn2SiO4 composite. PACS 81.05.-t; 81.10.Bk; 81.07.-b 相似文献
44.
45.
Summary Arsenic in marine samples was determined by gas chromatography with electron capture detection after derivatization with 2,3-dimercaptopropanol.
Biological tissues and sediments were analyzed after acid decomposition. For sea water, arsenic was preconcentrated by coprecipitation
with hydrous iron (III) oxide. The results obtained by this approach compare favourably with the certified values of the reference
materials analyzed.
Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984 相似文献
46.
47.
A weighing matrix of order n and weight m2 is a square matrix M of order n with entries from {-1,0,+1} such that MMT=m2I where I is the identity matrix of order n. If M is a group matrix constructed using a group of order n, M is called a group weighing matrix. Recently, group weighing matrices were studied intensively, especially when the groups are cyclic and abelian. In this paper, we study the abelian group weighing matrices that are symmetric, i.e.MT=M. Some new examples are found. Also we obtain a few exponent bounds on abelian groups that admit symmetric group weighing matrices. In particular, we prove that there is no symmetric abelian group weighing matrices of order 2pr and weight p2 where p is a prime and p≥ 5.Communicated by: K.T. Arasu 相似文献
48.
The proton conductivity of radiation-grafted ethylenetetrafluoroethylene-grafted-poly(styrene sulfonic) acid (ETFE-g-PSSA) and Nafion 117 membranes between 25 and -37 degrees C is reported. The freezing of water in the membranes, which strongly depends on the internal acid concentration, results in a 4-fold decrease in proton conductivity. The activation energies before and after the freezing of the membranes are approximately 0.15 and 0.4 eV, consistent with proton transport through liquid water and strongly bound water, respectively. Differential scanning calorimetry data show that up to 14 H(2)O molecules per H(+)/SO(3)(-) group remain unfrozen at subzero temperatures and are believed to be responsible for the low temperature conductivity that is observed. These results indicate that proton conductivity in membranes may be achieved via strongly bound and highly polarized water. 相似文献
49.
Shao Y Molnar LF Jung Y Kussmann J Ochsenfeld C Brown ST Gilbert AT Slipchenko LV Levchenko SV O'Neill DP DiStasio RA Lochan RC Wang T Beran GJ Besley NA Herbert JM Lin CY Van Voorhis T Chien SH Sodt A Steele RP Rassolov VA Maslen PE Korambath PP Adamson RD Austin B Baker J Byrd EF Dachsel H Doerksen RJ Dreuw A Dunietz BD Dutoi AD Furlani TR Gwaltney SR Heyden A Hirata S Hsu CP Kedziora G Khalliulin RZ Klunzinger P Lee AM Lee MS Liang W Lotan I Nair N Peters B Proynov EI Pieniazek PA Rhee YM 《Physical chemistry chemical physics : PCCP》2006,8(27):3172-3191
Advances in theory and algorithms for electronic structure calculations must be incorporated into program packages to enable them to become routinely used by the broader chemical community. This work reviews advances made over the past five years or so that constitute the major improvements contained in a new release of the Q-Chem quantum chemistry package, together with illustrative timings and applications. Specific developments discussed include fast methods for density functional theory calculations, linear scaling evaluation of energies, NMR chemical shifts and electric properties, fast auxiliary basis function methods for correlated energies and gradients, equation-of-motion coupled cluster methods for ground and excited states, geminal wavefunctions, embedding methods and techniques for exploring potential energy surfaces. 相似文献
50.
Donnelley M Siu KK Morgan KS Skinner W Suzuki Y Takeuchi A Uesugi K Yagi N Parsons DW 《Journal of synchrotron radiation》2010,17(6):719-729
During respiration, particles suspended in the air are inhaled and unless cleared by airway defences they can remain and affect lung health. Their size precludes the use of standard imaging modalities so we have developed synchrotron phase-contrast X-ray imaging (PCXI) methods to non-invasively monitor the behaviour of individual particles in live mouse airways. In this study we used these techniques to examine post-deposition particle behaviour in the trachea. PCXI was used to monitor the deposition and subsequent behaviour of particles of quarry dust and lead ore; fibres of asbestos and fibreglass; and hollow glass micro-spheres. Visibility was examined in vitro and ex vivo to avoid the complicating effects of surrounding tissue and respiratory or cardiac motion. Particle behaviour was then examined after deposition onto the tracheal airway surfaces of live mice. Each particle and fibre looked and behaved differently on the airway surface. Particles lodged on the airway shortly after deposition, and the rate at which this occurred was dependent on the particle type and size. After the live-imaging experiments, excised airway samples were examined using light and electron microscopy. Evidence of particle capture into the airway surface fluids and the epithelial cell layer was found. PCXI is a valuable tool for examining post-deposition particulate behaviour in the tracheal airway. These first indications that the interaction between airways and individual particles may depend on the particle type and size should provide a novel approach to studying the early effects of respired particles on airway health. 相似文献