Characterization of recombination centres in n-type Hg1-xCdxTe

The defect levels in Hg1-xCdxTe P+N junction photodiodes (x = 0.4) were first studied using deep-level transient spectroscopy. Two electron traps, E(1)(0.06) and E(2)(0.15), and two hole traps, H-1(0.075) and H-2(0.29), were obtained, Characteristic parameters-the minority lifetime of the devices and the dynamic resistance-area product at zero bias-are estimated according to these levels. Results show that these two minority levels may be important in controlling lifetime. We have studied the recombination mechanism of the hole trap H-2(0.29) further. It has a large activation energy and satisfies the formula sigma(T) = sigma(x) exp(-E(F)/E(T)). This reflects the fact that its recombination mechanism is multiphonon nonradiative recombination, which is rarely reported in narrow-bandgap materials.

P-选择素CR结构域功能的模拟预测

<正>选择素(selectin)与其配体间相互作用介导的细胞粘附在炎症级联反应、肿瘤转移和淋巴细胞归巢等病理、生理过程中起重要作用。其结构组成从远离细胞表面的N-末端到胞内C-末端,依次为:钙型凝集素功能区(Calcium-type lectin domain,Lec),类上皮生长因子功能区(Epidermal Growth Factor-like module,EGF),具有粘附补体蛋白作用的多个重复序列(Consensus Repeats,CRs),跨膜区(Transmembrane,TM)和胞内区

P-选择素Lectin结构域变构的模拟预测

<正>粘附分子选择素(selectin)家族成员与其配体间相互作用介导的细胞粘附在炎症级联反应、肿瘤转移和淋巴细胞归巢等病理、生理过程中起重要作用(Bevilacqua and Nelson,1993)。其结构组成从远离细胞表面的N-末端到胞内C-末端,依次为:钙型凝集素功能区(Calcium-type lectin domain,Lec),类上皮生长因子功

Adenovirus-mediated wild-type P53 Transfer radiosensitizes H1299 cells to subclinical-dose carbon-ion irradiation through the restoration of p53 function

To determine whether adenovirus-mediated wild-type p53 transfer after radiotherapy could radiosensitize non-small-cell lung cancer (NSCLC) cells to subclinical-dose carbon-ion beam (C-beam), H1299 cells were exposed to a C-beam or -ray and then infected with 5 MOI of AdCMV-p53 or GFP (C-beam or -ray with p53 or GFP).Cell cycle was detected by flow cytometric analysis. The apoptosis was examined by a fluorescent microscope with DAPI staining. DNA fragmentation was monitored by the TUNEL assay. P53 mRNA was detected by reverse-transcriptase polymerase chain reaction. The expression of p53, MDM2, and p21 was monitored by Western blot. Survival fractions were determined by colony-forming assay. The percentages of G1-phase cells in C-beam with p53 increased by 8.2%–16.0%, 5.2%–7.0%, and 5.8%–18.9%, respectively, compared with C-beam only, -ray with p53, or p53 only. The accumulation of G2-phase cells in C-beam with p53 increased by 5.7%–8.9% and 8.8%–14.8%, compared with those in -ray with p53 or p53 only, respectively. The percentage of apoptosis for C-beam with p53 increased by 7.4%–19.1%, 5.8%–11.7%, and 5.2%–19.2%, respectively, compared with C-beam only, -ray with p53, or p53 only. The level of p53 mRNA in C-beam with p53 was significantly higher than that in p53 only. The expression level of p53 and p21 in C-beam with p53 was significantly higher than that in both C-beam with GFP and p53 only. The survival fractions for C-beam with p53 were significantly less than those for the other groups (p 0.05). The data suggested that AdCMV-p53 transfer could more efficiently radiosensitize H1299 cells to subclinical-dose C-beam irradiation through the restoration of p53 function.

Effects of soil type on leaching and runoff transport of rare earth elements and phosphorous in laboratory experiments

Through leaching experiments and simulated rainfall experiments, characteristics of vertical leaching of exogenous rare earth elements (REEs) and phosphorus (P) and their losses with surface runoff during simulated rainfall in different types of soils (terra nera soil, cinnamon soil, red soil, loess soil, and purple soil) were investigated. Results of the leaching experiments showed that vertical transports of REEs and P were relatively low, with transport depths less than 6 cm. The vertical leaching rates of REEs and P in the different soils followed the order of purple soil > terra nera soil > red soil > cinnamon soil > loess soil. Results of the simulated rainfall experiments (83 mm h(-1)) revealed that more than 92% of REEs and P transported with soil particles in runoff. The loss rates of REEs and P in surface runoff in the different soil types were in the order of loess soil > terra nera soil > cinnamon soil > red soil > purple soil. The total amounts of losses of REEs and P in runoff were significantly correlated.

Surface enhanced Raman scattering of p-aminothiophenol self-assembled monolayers in sandwich structure fabricated on glass

A sandwich structure consisting of Ag nanoparticles (NPs), p-aminothiophenol (p-ATP) self-assembled monolayers (SAMs), and Ag NPs was fabricated on glass and characterized by surface enhanced Raman scattering (SERS). The SERS spectrum of a p-ATP SAM in such sandwich structure shows that the electromagnetic enhancement is greater than that on Ag NPs assembled on glass. The obtained enhancement factors (EF) on solely one sandwich structure were as large as 6.0 +/- 0.62x10(4) and 1.2 +/- 0.62x10(7) for the 7a and 3b(b(2)) vibration modes, respectively. The large enhancement effect of p-ATP SAMs is likely a result of plasmon coupling between the two layers of Ag NP (localized surface plasmon) resonance, creating a large localized electromagnetic field at their interface, where p-ATP resides. Moreover, the fact that large EF values (similar to 1.9 +/- 0.7x10(4) and 9.4 +/- 0.7x10(6) for the 7a- and b(2)-type vibration modes, respectively) were also obtained on a single sandwich structure of Au NPs/p-ATP SAMs/Ag NPs in the visible demonstrates that the electromagnetic coupling does not exist only between Ag NPs but also between Au and Ag NPs.

The direct synthesis of wholly aromatic poly(p-phenylene)s bearing sulfobenzoyl side groups as proton exchange membranes

Sulfonated poly(p-phenylene)s (SPPs) containing sulfonic acid groups in their side chains had been directly synthesized by Ni(0) catalytic coupling of sodium 3-(2,5-dichlorobenzoyl)benzenesulfonate and 2,5-dichlorobenzophenone. The synthesized copolymers possessed high molecular weights revealed by their high viscosity, and the formation of tough and flexible membranes by casting from DMAc solution. The copolymers exhibited excellent oxidative stability and mechanical properties due to their fully aromatic structure extending through the backbone and pendent groups. Transmission electron microscopic (TEM) analysis revealed that these side-chain type SPP membranes have a microphase-separated structure composed of hydrophilic side-chain domains and hydrophobic polyphenylene main chain domains. The proton conductivities of copolymer membranes increased with the increase of IEC and temperature, reaching values above 3.4 x 10(-1) S/cm at 120 degrees C, which are almost 2-3 times higher than that of Nafion 117 at the same measurement conditions. Consequently, these materials proved to be promising as proton exchange membranes.

Synthesis, characterization and fabrication on a glassy carbon electrode of a tetra-iron substituted sandwich-type pentadecatungstodiarsenate heteropolyanion

A novel sandwich-type compound, Na-12[Fe-4(H2O)(2)(As2W15O56)2].41H(2)O, has been synthesized. The compound was well-characterized by means of IR, UV-vis, W-183 NMR and elemental analyses. The compound crystallizes in the triclinic, P (1) over bar symmetry group. The structure of the compound is similar to that of Na-16[M-4(H2O)(2)(As2W15O56)(2)].nH(2)O (M = Cu, Zn, Co, Ni, Mn, Cd), and consists of an oxo-aqua tetranuclear iron core, [(Fe4O14)-O-III(H2O)(2)], sandwiched by two trivacant alpha-Wells-Dawson structural moieties, alpha-[As2W15O56]. Redoxelectrochemistry of the compound has been studied in buffer solutions at pH = 4.7 using polarography and cyclic voltammetry ( CV). The compound exhibited four one-electron couples associated with the Fe(III) center followed by three four-electron redox processes attributed to the tungsten-oxo framework. The compound-containing monolayer and multilayer films have been fabricated on a 4-aminobenzoic acid modified glassy carbon electrode surface by alternating deposition with a quaternized poly(4-vinylpyridine) partially complexed with [Os(bpy)(2)Cl](2+/-). CV, X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy and atomic force microscopy (AFM) have been used to characterize the multilayer films.

An organic-inorganic vanadium oxide with one-dimensional ladder-type structure: hydrothermal synthesis, structure and characterization of [V4O10(o-phen)(2)]

A novel organic-inorganic hybrid vanadium oxide [V4O10(o-phen)(2)], involving all vanadium atoms present in +5 oxidation, has been hydrothermally synthesized and characterized by elemental analysis, IR, UV-vis, ESR, XPS spectra and TG-DTA thermal analysis. The single-crystal X-ray diffraction shows that the red-brown crystal is formed in the triclinic system, space group P (1) over bar, a = 9.782(2), b = 6.5124(14), c = 19.765(4) Angstrom, alpha = 89.94(2)degrees, beta = 100.66(2)degrees, gamma = 89.86(2)degrees. The title compound exhibits an infinite one-dimensional ladder-type tetravanadate skeleton with organonitrogen donors of o-phenanthroline ligands coordinated directly to the vanadium oxide framework.

Preparation, characterization and luminescent properties of MCM-41 type materials impregnated with rare earth complex

Hybrid materials incorporating Eu-(TTA)(3). 2H(2)O (7hereafter designated as Eu-TTA, with TTA: thenoyltrifluoroacetone) in unmodified or modified MCM-41 by 3-aminopropyl-triethoxysilane (APTES) were prepared by impregnation method. The obtained materials were characterized using X-ray diffraction (XRD), IR and diffuse reflectance spectroscopy and luminescence spectra. All the hybrid samples exhibited the characteristic emission bands of EU3+ under UV light excitation at room temperature, and the excitation spectra showed significant blue-shifts compared to the pure rare-earth complex. Although the red emission intensity in the modified hybrid was almost the half of the red emission intensity in the pure Eu-TTA complex at room temperature, the hybrid showed a much higher thermal stability due to the shielding character of the MCM-41 host.

Sol-gel-derived graphite organosilicate composite electrodes bulk-modified with Keggin-type alpha-germanomolybdic acid

A novel inorganic-organic hybrid material incorporating graphite powder and Keggin-type alpha -germanomolybdic acid (GeMo12) in methyltrimethoxysilane-based gels has been produced by the sol-gel technique and used to fabricate a chemically bulk-modified electrode. GeMo12 acts as a catalyst, graphite powder ensures conductivity by percolation, the silicate provides a rigid porous backbone, and the methyl groups endow hydrophobicity and thus limit the wetting section of the modified electrode. The GeMo12-modified graphite organosilicate composite electrode was characterized by cyclic and square-wave voltammetry. The modified electrode shows a high electrocatalytic activity toward the reduction of bromate, nitrite and hydrogen peroxide in acidic aqueous solution. In addition, the chemically-modified electrode has some distinct advantages over the traditional polyoxometalate-modified electrodes, such as long-term stability and especially repeatability of surface-renewal by simple mechanical polishing.

An investigation on ion solvation and ion association in a gel-type solid state polymer electrolyte

Ion salvation and ion association in polytriethylene glycol dimethacrylate (PTREGD)-LiClO4 gel-type polymer electrolytes were investigated. It was found that the fraction of solute existing as single ions (alpha(i)) decreases and that of triple ions (alpha(i)) increases linearly with increasing LiClO4 concentration, while for ion pairs, as the salt concentration increases, its fraction (alpha(p)) increases first and then falls down. The findings can be rationalized by the fact that the ionic conductance of the polymer electrolyte may be mainly contributed by triple ions and higher ionic aggregates with unequal numbers of positive and negative charges in the salt concentration range of practical significance, i.e. in the range of 0.5-1.5 mol/l. The temperature dependence of these fractions was also examined. In the case of tetraethylene glycol as the solvent, alpha(i) and alpha(p) increase as the temperature is raised, but alpha(t) decreases as the temperature increases from 25 degrees C to 85 degrees C. It seems that the increase of alpha(i) and alpha(p) results from the redissociation of triple ions at higher temperature, The same changing trend of those fractions is also observed when PEG(400) is used as the solvent.

SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF THE DAWSON-TYPE TUNGSTOPHOSPHATE HETEROPOLY COMPLEXES SUBSTITUTED BY NIOBIUM

Eight new complexes alpha(2)-M(7-m)H(m)[P2W17NbO62]. H2O and alpha-1, 2, 3-M(g-m)H(m) [P2W15Nb3O62]. XH(2)O(M=K, TMA, TEA, TBA) were synthesized and characterized by IR and UV spectroscopy, polarography, XPS and XRD methods. P-31 and W-183 NMR studies show that the niobium atoms in the anions are on the polar sites. The crystal of alpha-1, 2, 3-K7H2 [P2W15Nb3O62]. 30H(2)O is hexagonal, its cell parameters: a=1.9836(4), b=1.9836(9), c=1.5498(6)nm, alpha=beta=90 degrees, gamma=120 degrees.

An ancient C-type lectin in Chlamys farreri (CfLec-2) that mediate pathogen recognition and cellular adhesion

C-type lectins are a superfamily of Ca2+ dependent carbohydrate-recognition proteins which play significant diverse roles in nonself-recognition and clearance of invaders. In the present study, a C-type lectin (CfLec-2) from Zhikong scallop Chlamys farreri was selected to investigate its functions in innate immunity. The mRNA expression of CfLec-2 in hemocytes was significantly up-regulated (P < 0.01) after scallops were stimulated by LPS. PGN or beta-glucan, and reached the highest expression level at 12h post-stimulation, which was 72.5-, 23.6- or 43.8-fold compared with blank group, respectively. The recombinant Cflec-2 (designated as rCfLec-2) could bind LPS, PGN, mannan and zymosan in vitro, but it could not bind beta-glucan. Immunofluorescence assay with polyclonal antibody specific for Cflec-2 revealed that CfLec-2 was mainly located in the mantle, kidney and gonad. Furthermore, rCfLec-2 could bind to the surface of scallop hemocytes, and then initiated cellular adhesion and recruited hemocytes to enhance their encapsulation in vitro, and this process could be specifically blocked by anti-rCfLec-2 serum. These results collectively suggested that CfLec-2 from the primitive deuterostome C. farreri could perform two distinct immune functions, pathogen recognition and cellular adhesion synchronously, while these functions were performed by collectins and selectins in vertebrates, respectively. The synchronous functions of pathogen recognition and cellular adhesion performed by CfLec-2 tempted us to suspect that CfLec-2 was an ancient form of C-type lectin, and apparently the differentiation of these two functions mediated by C-type lectins occurred after mollusk in phylogeny. (C) 2010 Elsevier Ltd. All rights reserved.