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981.
First-principles calculations using the augmented plane wave plus local orbitals method, as implemented in the WIEN2K code, have been carried out to study the A-B intersite charge transfer and the correlated electrical and magnetic properties of the perovskite BiCu(3)Fe(4)O(12), especially as regards the charge transfer. The results indicate that the charge transfer between A-site Cu and B-site Fe is by way of O 2p orbitals, and during this process orbital hybridization plays an important role. More importantly, the charge transfer is of 3d(9) + 4d(5)L(0.75) →3d(9)L + 4d(5) type (here L denotes an oxygen hole or a ligand hole). During this process, the magnetic interaction experiences a transition from Cu-Fe ferrimagnetic coupling to G-type antiferromagnetic coupling within B-site Fe with paramagnetic Cu(3+). As to electrical property, it undergoes a metal to insulator transition. All our calculated results are consistent with the available experimental results. 相似文献
982.
Ma M He Z Yang J Chen F Wang K Zhang Q Deng H Fu Q 《Langmuir : the ACS journal of surfaces and colloids》2011,27(21):13072-13081
In this Article, the morphological evolution in the blend thin film of polystyrene (PS)/poly(ε-caprolactone) (PCL) was investigated via mainly AFM. It was found that an enriched two-layer structure with PS at the upper layer and PCL at the bottom layer was formed during spinning coating. By changing the solution concentration, different kinds of crystal morphologies, such as finger-like, dendritic, and spherulitic-like, could be obtained at the bottom PCL layer. These different initial states led to the morphological evolution processes to be quite different from each other, so the phase separation, dewetting, and crystalline morphology of PS/PCL blend films as a function of time were studied. It was interesting to find that the morphological evolution of PS at the upper layer was largely dependent on the film thickness. For the ultrathin (15 nm) blend film, a liquid-solid/liquid-liquid dewetting-wetting process was observed, forming ribbons that rupture into discrete circular PS islands on voronoi finger-like PCL crystal. For the thick (30 nm) blend film, the liquid-liquid dewetting of the upper PS layer from the underlying adsorbed PCL layer was found, forming interconnected rim structures that rupture into discrete circular PS islands embedded in the single lamellar PCL dendritic crystal due to Rayleigh instability. For the thicker (60 nm) blend film, a two-step liquid-liquid dewetting process with regular holes decorated with dendritic PCL crystal at early annealing stage and small holes decorated with spherulite-like PCL crystal among the early dewetting holes at later annealing stage was observed. The mechanism of this unusual morphological evolution process was discussed on the basis of the entropy effect and annealing-induced phase separation. 相似文献
983.
Meng XW Ha W Cheng C Dong ZQ Ding LS Li BJ Zhang S 《Langmuir : the ACS journal of surfaces and colloids》2011,27(23):14401-14407
This article studies the self-assembly of alginate-graft-poly(ethylene glycol) (Alg-g-PEG) and α-cyclodextrin (α-CD) in aqueous solution. It was found that they could form hollow spheres because of the formation of coil-rod Alg-g-PEG/α-CD inclusion complexes. In these Alg-g-PEG/α-CD complexes, the α-CDs are stacked along the PEG side chains to form a rod block, and alginate main chains act as a coil block. More rod-like blocks in Alg-g-PEG/α-CD favor the formation of small assemblies. The assemblies of Alg-g-PEG/α-CD show a dependence on concentration, temperature, pH, and salt concentration. At low concentration (below 0.125%) or high temperature (above 32 °C), Alg-g-PEG/α-CD particles were unstable and disrupted. Increasing the salt or decreasing the pH resulted in the aggregation of Alg-g-mPEG/α-CD particles, as detected by the increase in the recorded hydrodynamic diameter (D(h)). 相似文献
984.
Lange H Maultzsch J Meng W Mollenhauer D Paulus B Peica N Schlecht S Thomsen C 《Langmuir : the ACS journal of surfaces and colloids》2011,27(11):7258-7264
We demonstrate a phase transfer method to create stable colloidal solutions of Au nanoparticles with 4-methoxypyridine ligands. We then investigate the adsorption behavior of 4-methoxypyridine onto gold surfaces by Raman spectroscopy, DFT calculations, and (1)H NMR. In contrast to unsubstituted pyridine and the frequently used (N,N-dimethylamino)pyridine (DMAP), a flat adsorption of 4-methoxypyridine on gold was found. 相似文献
985.
Material segregation has been reported for industrial spray-dried milk powders, which indicates potential material migration during drying process. The relevant colloidal transport phenomenon and the underlying mechanism are still under debate. This study extended the glass-filament single droplet drying technique to observe not only the drying behaviour but also the dissolution behaviour of the correspondingly dried single particle. At progressively longer drying stage, a solvent droplet (water or ethanol) was attached to the semi-dried milk particle and the interaction between the solvent and the particle was video-recorded. Based on the different dissolution and wetting behaviours observed, material migration during milk drying was studied. Fresh skim milk and fresh whole milk were investigated using water and ethanol as solvents. Fat started to accumulate on the surface as soon as drying was started. At the initial stage of drying, the fat layer remained thin and the solubility of the semi-dried milk particle was much affected by lactose and protein present underneath the fat layer. Fat kept accumulating at the surface as drying progressed and the accumulation was completed by the middle stage of drying. The results from drying of model milk materials (pure sodium caseinate solution and lactose/sodium caseinate mixed solution) supported the colloidal transport phenomena observed for the milk drying. When mixed with lactose, sodium caseinate did not form an apparent solvent-resistant protein shell during drying. The extended technique of glass-filament single droplet approach provides a powerful tool in examining the solubility of individual particle after drying. 相似文献
986.
Rui‐Bin Liu Jian‐Jun Zhang Dr. Bo Tong Xin Liu Yang Yang Chang‐Gong Meng 《无机化学与普通化学杂志》2011,637(2):269-275
Reactions between CoO, ZnCl2 (or ZnBr2), and molten citric acid (Hcit) led to the formation of two 3d‐3d heterometallic coordination frameworks: [ZnCo(Hcit)Cl] ( 1 ) and [ZnCo(Hcit)Br] ( 2 ). X‐ray structure analyses show that both compounds 1 and 2 crystallize in the monoclinic space group P21/n [ 1 : a = 5.8699(5) Å, b = 17.7963(13) Å, c = 9.2152(8) Å, β = 106.806(4) °, Z = 4, V = 921.53(13) Å3; 2 : a = 5.909(3) Å, b = 17.798(8) Å, c = 9.302(5) Å, β = 106.374(7) °, Z = 4, V = 938.6(8) Å3]. The structures of the two compounds are almost the same except for the terminal halogen ligand. Both of them are 3D frameworks based on citric acid bridging ligands and a 1D backbone chain built of corner‐shared {CoO6} and {ZnO3Cl} polyhedra. Photoluminescence and thermal stabilities of the compounds were studied. 相似文献
987.
This short communication describes the interaction between toll-like receptor 4 (TLR4) and lipopolysaccharide (LPS, its specific ligand) using analytical methods. Their interaction has been evidenced in many reports. Nevertheless, there are few reports focused on their binding constant. In this research, the interaction between TLR4 and LPS is investigated using mobility shift method by CZE. To optimize the electrophoresis conditions, the effecting factors, running buffer, sample concentration, injection duration, and operation voltage of electrophoretic on the mobility shift are studied in detail. Electrophoresis conditions were described as follows: borate buffer (pH 7.4, 20 mM), 5 s for 50 mbar pressure injection duration, and 13 kV of separation voltage in 41.5 cm fused silica capillary with 75 μm id and 375?μm od. The combination constant of TLR4 and LPS is calculated using Scatchard methods. The Scatchard liner correlation is y=-0.0165x+0.1456, binding constant is K=1.65 x 10? (g/mL)?1. 相似文献
988.
Dan-Dan Liu Chun-Jing Zhang Hua-Xin Meng Zhi-Chao Zhang Chun-Xia Zhang 《Journal of solid state chemistry》2011,184(6):1355-1360
Four novel compounds based on α-metatungstate [H2W12O40]6− (W12) and Ln-organic complexes, (NH4)4[Ln2(L)2(H2O)9(H2W12O40)]·nH2O (Ln=EuIII (1), GdIII (2), DyIII (4), n=11; TbIII (3), n=12; L=pyridine-3,5-dicarboxylate dianion) have been synthesized in aqueous solution and characterized by element analysis, IR spectrometry and thermogravimetric analysis. Single-crystal X-ray diffraction analyses reveal these compounds are isostructural with a P21/n space group. The W12 cluster acting as a tridentate ligand connects three Ln3+ ions, in turn, each Ln2 ion links two W12 clusters, as a result, a W12-Ln polymeric chain is formed. Coordination of pyridine-3,5-dicarboxylate ligands to the Ln3+ ions leads to a Ln-L polymeric chain. The two chains, W12-Ln and Ln-L, share Ln2 ions, resulting in a 2-D layer. Ring coordination of pyridine-3,5-dicarboxylate and W12 to the Ln ions changes some bond angles of W12 that leads to a slight distortion of W12 and splitting of vibration band of W-Oc-W. Solid-state photoluminescence properties of compounds 1−4 have been investigated. 相似文献
989.
A differential pulse voltammetric method was developed for the simultaneous determination of paracetamol, 4-aminophenol and dopamine at pH 7.0 using a glassy carbon electrode (GCE) coated with gold nanoparticles (AuNPs) and a layered double hydroxide sodium modified with dodecyl sulfate (SDS-LDH). The modified electrode displays excellent redox activity towards paracetamol, and the redox current is increased (and the corresponding over-potential decreased) compared to those of the bare GCE, the AuNPs-modified GCE, and the SDS-LDH-modified GCE. The modified electrode enables the determination of paracetamol in the concentration range from 0.5 to 400???M, with a detection limit of 0.13???M (at an S/N of 3). The sensor was successfully applied to the stimultaneous determination of paracetamol and dopamine, and of paracetamol and 4-aminophenol, respectively, in pharmaceutical tablets and in spiked human serum samples. Figure
1. Gold nanoparticles and organophillic layered double hydroxide modified glassy carbon electrode was fabricated. 2. The modified electrode displayed excellent redox activity towards paracetamol. 3. This electrode was successfully applied to the simultaneous determination of paracetamol and dopamine, and of paracetamol and 4-aminophenol, respectively 相似文献
990.
Zuchao Meng Bin Liu Jianbin Zheng Qinglin Sheng Hongfang Zhang 《Mikrochimica acta》2011,175(3-4):251-257
We describe a modified glassy carbon electrode (GCE) for the sensitive determination of nitrite in waste water samples. The GCE was modified by electrodeposition of cobalt oxide nanoparticles on multi-walled carbon nanotubes (MWCNTs) deposited on a conventional GCE. Scanning electron microscopy and electrochemical techniques were used for the characterization of the composite material which is very uniform and forms a kind of nanoporous structure. Electrochemical experiments showed that the modified electrode exhibited excellent electrocatalytic properties for nitrite. Amperometry revealed a good linear relationship between peak current and nitrate concentration in the 0.5 to 250???M range with a detection limit of 0.3???M (S/N?=?3). The method has been applied to the amperometric detection of nitrite. The modified electrode displays good storage stability, reproducibility, and selectivity for a promising practical application. Figure
The dense and entangled CoOx/MWCNTs nanocomposite showed a three-dimensional nanoporous structure. The three-dimensional nanoporous structure provided ample space to allow fast mass transport of ions through the electrolyte/electrode interface as well as a conductive network for enhancing electronic conductivity which was favorable to the catalytic application of CoOx. 相似文献