354 resultados para SH-SY5Y
Resumo:
Nickel catalyst supported on carbon was made by reduction of nickelous nitrate with hydrogen at high temperature. Ni/ C catalyst characterization was carried out by XRD. It was found that the crystal phase of NiS and NiS2 appeared in the impregnated catalyst. Ni/ C and Pt/ C catalysts gave high performance as the positive and negative electrodes of a sodium polysulfide/ bromine energy storage cell, respectively. The overpotentials of the positive and negative electrodes were investigated. The effect of the electrocatalyst loading and operating temperature on the charge and discharge performance of the cell was investigated. A power density of up to 0.64 W cm(-2) ( V = 1.07 V) was obtained in this energy storage cell. A cell potential efficiency of up to 88.2% was obtained when both charge and discharge current densities were 0.1 A cm(-2).
Resumo:
Ion - molecule complexes of magnesium cation with ethyl isocyanate were produced in a laser- ablation supersonic expansion nozzle source. Photo- induced reactions in the 1: 1 complexes have been studied in the spectral range of 230 - 410 nm. Photodissociation mass spectrometry revealed the persistent product Mg+ from nonreactive quenching throughout the entire wavelength range. As for the reactive channels, the photoproducts, Mg+OCN and C2H5+, were produced only in the blue absorption band of the complex with low yields. The action spectrum of Mg+(OCNC2H5) consists of two pronounced peaks on the red and blue sides of the Mg+ 3(2)P <-- 3(2)S atomic transition. The ground state geometry of Mg+ - OCNC2H5 was fully optimized at B3LYP/6- 31 - G** level by using GAUSSIAN 98 package. The calculated absorption spectrum of the complex using the optimized structure of its ground state agrees well with the observed action spectrum. Photofragment branching fractions of the products are almost independent of the photolysis photon energy for the 3P(x,y,z) excitations. The very low branching ratio of reactive products to nonreactive fragment suggests that evaporation is the main relaxation pathway in the photo- induced reactions of Mg+ (OCNC2H5). (C) 2003 American Institute of Physics.
Resumo:
The heat capacities of p-chlorobenzoic acid were measured in the temperature range from 80 to 580 K by means of an automatic adiabatic calorimeter equipped with a small sample cell of internal volume of 7.4cm(3). The construction and procedures of the calorimetric system were described in detail. The performance of this calorimetric apparatus was evaluated by heat capacity measurements on alpha-Al2O3. The deviations of experimental heat capacities from the corresponding smoothed values lie within +/-0.28 per cent, while the inaccuracy is within +/-0.40 per cent, compared with the recommended reference data in the whole experimental temperature range. A fusion transition at T = 512.280 K was found from the C-p-T curve of p-chlorobenzoic acid. The enthalpy and entropy of the phase transition, as well as the thermodynamic functions {G((T)) - G((298.15))}, {H-(T) - H-(298.15)} and {S-(T) - S-298.15}, were derived from the heat capacity data. The mass fraction purity of p-chlorobenzoic acid sample used in the present calorimetric study was determined to be 0.99935 by fraction melting approach. (C) 2002 Elsevier Science Ltd. All rights reserved.
Resumo:
The heat capacity (C-p) of nanocrystalline nickel (nc-Ni, 40 mn crystallite size) has been measured over the temperature range of 78-370 K with a high-resolution automated adiabatic calorimeter. The measured results are compared with the C-p values of the corresponding coarse-grained crystal, and an enhancement of heat capacity of the nanocrystalline nickel was observed to be 2-4% in the temperature range between 100 and 370 K. The thermal stability of the nanocrystalline nickel sample was determined by a differential scanning calorimeter and a thermogravimetric system. The melting point of nc-Ni is the same as that of the corresponding coarse-grained crystalline nickel and the sample is stable at temperature lower than 500 K. (C) 2002 Elsevier Science B.V. All rights reserved.
Resumo:
The structures, properties and electron transfer reactivity of the ClO/ClO- coupling system are studied in this paper at ab initio (UHF and UMP2) levels and the Density Functional Theory (DFT: UB3LYP, UB3P86, UB3PW91) levels employing 6311 + G(3df) basis set and on the basis of the Golden-rule of the time-dependent perturbation theory. Investigations indicate that the results obtained using the UB3LYP method employing 6-311 + G(3df) basis set is in excellent agreement with the experiment. For this coupling system, six stable coupling modes have been found which correspond to six different encounter complexes and denote six different electron transfer mechanism: four O-O directly linked structures (one collinear: D-h, one anti-parallel: C-s, two twist: C-2) and two Cl-O linked structures (cis- and anti- C-s structures). The activation energies, the stabilization energies and the electronic coupling matrix elements have also been calculated for the electron transfer reactions via these six different mechanism at the UB3LYP/6-311 + G(3df) level, and then the electron transfer rates are determined at the same level. The most favorable coupling mode to the electron transfer is the anti-parallel mechanism. The averaged electron transfer rate is about 5.58 X 10(11) M-1 s(-1). It is also implied that the B3LYP method can give more reasonable results for the electron transfer reactivity of this system. (C) 2003 Elsevier B.V. All rights reserved.
Resumo:
Various analytical physical models are presented to extract the photodissociation dynamics information from the data obtained in the femtosecond pump-probe experiment. The single- and double-component models are employed to explain the single- and double-channel dissociation of parent molecules. Another single-component model for fragment dissociation or deexcitation is also presented. All cases are explanatorily demonstrated on the pump-probe experimental data.
Resumo:
By using the home-made femtosecond laser system and the time-of-flight mass spectrometer, the decay dynamics of excited carbon disulfide (CS2) and ammonia (NH3) are investigated in real time by pump-probe multiphoton ionization detection. The estimated lifetime constant of the NH3 (A) over tilde (1)A(2)' state (51+/-4 fs) agreed quite well with the literature report. For the first time, the decay lifetime constants of the NH3 (E) over tilde'(1)A(1)' state (937+/-93 fs), the CS2 (a) over tilde (3)A(2) state (153+/-10 fs), and the CS2 Rydberg state [(3)/(2)]6ssigma(g) ((3)Pi(g)) (948+/-23 fs) are obtained.
Resumo:
The predissociation decay behavior of molecule carbonyl sulfide (OCS) has been investigated by resonance-enhanced multiphoton ionization spectroscopy using the pump-probe technique of dichroic femtosecond lasers in real time. The lifetime of excited OCS around 74 720 cm(-1) by two-photon absorption of 268 nm, corresponding to upsilon(1)=1 of the Rydberg state [(2)Pi(1/2)]4ppi((1)Sigma(+)), is directly determined to be tau(D)=1071+/-11 fs. This picosecond decay process indicates that the excited state is predissociative. The temporal information of dissociation enriches the knowledge of the potential-energy surface of the associative excited state.
Resumo:
日本落叶松的微体繁殖中 ,茎诱导阶段WPM +Zea 1.0 0mg/L +IAA 1.0 0mg/L、SH +Zea 0 .2 0mg/L +IAA 0 .0 5mg/L或改良MS +Zea 0 .0 1~ 0 .5 0mg/L等 3种培养基均适用 ,诱导效率与供体材料的质量有关 ,取材以初春芽苞萌动时为好。根诱导阶段的培养基为改良MS +NAA 0 .10mg/L +IBA 0 .30mg/L +0 .15 %AC(活性炭 ) ,低剂量的AC ,夜间降低培养温度至 2 0℃并与继代培养相结合 ,可促进生根率的提高。实验经 8次继代培养成功地实现了根、茎器官的再生。对于成龄材料 ,认为反复继代可能是最有效的恢复幼年生长特性的途径之一。同时指出微体繁殖过程中应当注意遗传材料的异质性对诱导效率的影响。
Resumo:
The objective of this study was to evaluate degradation behavior and the feasibility of biodegradable polymeric stents in common bile duct (CBD) repair and reconstruction. Various molar ratios of lactide (LA) and glycolide (GA) in poly(L-lactide-co-glycolide) (PLGA) were synthesized and processed into a circular tubing of similar to 10.0 mm outer diameter and a wall thickness of about 2.0 mm.
Resumo:
Nanoporous VSB-5 nickel phosphate molecular sieves with relatively well controllable sizes and morphology of microspheres assembled from nanorods were synthesized at 140 degrees C over a short time in the presence of hexamethylenetetramine (HMT) by a facile hydrothermal method. The pH value, reaction time, and ratio of HMT to NaHPO2-H2O crucially influence the morphology and quality of the final products.
Combustion synthesis and luminescent properties of the Eu3+-doped yttrium oxysulfide nanocrystalline
Resumo:
Nanocrystallinc Y2O2S:Eu3+ was successfully prepared with a combustion synthesis method, the corresponding bulk Y2O2S:Eu3+ was synthesized by conventional sulfur flux method. The results of XRD indicated that both bulk and nanocrystalline Y2O2S:Eu3+ have Pure hexagonal phases. The crystallite size was calculated to be about 20 nm according to Scherrer formula, which was consistent with the size as indicated by transmission electron microscopy (TEM).
Resumo:
The chemical bond properties, lattice energies, linear expansion coefficients, and mechanical properties of ReVO4 (Re = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc, Y) are investigated systematically by the dielectric chemical bond theory. The calculated results show that the covalencies of Re-O bonds are increasing slightly from La to Lu and that the covalencies of V-O bonds in crystals are decreasing slightly from La to Lu. The linear expansion coefficients decrease progressively from LaVO4 to LuVO4; on the contrary, the bulk moduli increase progressively. Our calculated results are in good agreement with some experimental values for linear expansion coefficients and bulk moduli.
Resumo:
Ligand-to-metal charge transfer energies of YBO3:Eu have been investigated from the chemical bond viewpoint. The chemical bond parameters, such as the covalency, the polarizability of the chemical bond volume, and the presented charge of the ligands in the chemical bond have been quantitatively determined based on the dielectric theory of complex crystal. We calculated the environmental factor (h(e)), which is the major factor influencing the charge transfer energy in the compounds. The calculated results show that the suitable group space of YBO3 is C2/c. The method provides us with a supplementary tool to judge the proper structure when the structure of the crystal has many uncertain space groups.
Resumo:
Bulk and nano-materials Sr2CeO4 were prepared by solid-state reaction and sol-gel technique, respectively. Photoluminescence shows that luminescence has the characteristic of a ligand-to-metal charge transfer (CT) emission. Compared with bulk Sr2CeO4, the nano-material exhibits stronger emission intensity, longer decay time, and higher CT excitation energy. Three CT excitation peaks were observed in both bulk and nano samples.