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191.
We present electronic and optical properties of the hydrogen terminated gallium arsenide nanoparticles using time dependent density functional theory (TD-DFT). The electronic and optical properties of the GaAs nanoparticles were calculated at presence of the uniform external electric field in the range from 0 to 0.51 V/Å. The induced electric filed can decrease the HOMO–LUMO gap of the nanoparticles and the mount of these reductions increases with gain of the electric field strength. 相似文献
192.
Density functional theory (DFT) calculations have been performed to investigate the availabilities and properties of boron nitride nanotubes (BNNTs) with quadrangular cross sections. To achieve the purposes, the original structure of a representative BNNT was individually decorated by the carbon and silicon atoms to make the C-BNNT and Si-BNNT models. The sp3 hybridizations were set for the C and Si atoms to make possible the formation of the quadrangular cross sections for the BNNTs. The optimized results indicated that the investigated models could be stabilized; however, they showed different properties. The atomic scale properties based on computations of quadrupole coupling constants (CQ) also approved different properties for the C-BNNT and Si-BNNT models. Moreover, the CQ parameters indicated that the properties of C-BNNT could be considered similar to the original BNNT; however, more discrepancies were observed for the Si-BNNT. 相似文献
193.
Reza Yousefi Sadaf Aghevlian Fatemeh Mokhtari Hamidreza Samouei Mehdi Rashidi S. Masoud Nabavizadeh Zohreh Tavaf Zahra Pouryasin Ali Niazi Reza Faghihi Mohammad Mehdi Papari 《Applied biochemistry and biotechnology》2012,167(4):861-872
The development of resistance and unwanted harmful interaction with other biomolecules instead of DNA are the major drawbacks for application of platinum (Pt) complexes in cancer chemotherapy. To conquer these problems, much works have been done so far to discover innovative Pt complexes. The objective of the current study was to evaluate the anti cancer activities of a series of four and five-coordinated Pt(II) complexes, having deprotonated 2-phenyl pyridine (abbreviated as C^N), biphosphine moieties, i.e., dppm?=?bis(diphenylphosphino) methane (Ph2PCH2PPh2) and dppa?=?bis(diphenylphosphino)amine (Ph2PNHPPh2), as the non-leaving carrier groups. The growth inhibitory effect of the Pt complexes [Pt(C^N)(dppm)]PF6: C 1 , [Pt(C^N)(dppa)]PF6: C 2 , and [Pt(C^N)I(dppa)]: C 3 , toward the cancer cell lines was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. In addition, the florescence quenching experiments of the interaction between human serum albumin (HSA) and the Pt complexes were performed in order to obtain the binding parameters and to evaluate the denaturing properties of these complexes upon binding to the general carrier protein of blood stream. The structure?Cactivity relationship studies reveal that four-coordinated Pt complexes C 1 and C 2 with both significant hydrophobic and charge characteristics, not only exhibit strong antiproliferation activity toward the cancer cell lines, but also they display lower denaturing effect against carrier protein HSA. On the other hand, five-coordinated C 3 complex with the unusual intermolecular NH??Pt hydrogen binding and the intrinsic ability for oligomerization, exhibits poor anticancer activity and strong denaturing property. The current study reveals that the balance between charge and hydrophobicity of the Pt complexes, also their hydrogen binding abilities and coordination mode are important for their anticancer activities. Moreover, this study may suggest C 1 and C 2 as the potential template structures for synthesis of new generation of four-coordinated Pt complexes with strong anticancer activities and weak denaturing effects against proteins. 相似文献
194.
195.
Leila Bakhtiyari Fereshteh Moghimi Seyed Soheil Mansouri Ali Farsi Masoud M. Malek-Shah 《Research on Chemical Intermediates》2012,38(3-5):965-982
The production of metal concentrates during mineral processing of ferrous and non-ferrous metals involves a variety of highly corrosive chemicals which deteriorate common mild steel as the material of choice in the construction of such lines, through rapid propagation of localized pitting in susceptible parts, often in sensitive areas. This requires unscheduled maintenance and plant shut down. In order to test the corrosion resistance of different available materials as replacement materials, polarization and electrochemical impedance spectroscopy (EIS) tests were carried out. The EIS numerical outputs were then transformed into an equivalent electric circuit using Z-View software, and the predictive behavior was contrasted with actual performance after long-term immersion, depicted through SEM, EDS, XRD and weight change observations. Also, results of pits and cracks, obtained with climax software-enhanced polarization resistance, and reduced capacitance added to much diminished current densities, verified the acceptable performance of CK45 compared with high priced stainless steel substitutes with comparable operational life. Therefore, CK45 can be a suitable alternative in steel constructions which are exposed to super-alkaline and corrosive environments. 相似文献
196.
Masoud Heydari Hamid Moharrami Hadi Yazdani-Paraei 《Journal of Optimization Theory and Applications》2012,155(3):1025-1046
In this paper the nonlinear analysis and design optimization of guyed masts is addressed. The mast is modeled as a 3D truss and is supported by catenary cable elements that have nonlinear elastic behavior. For nonlinear static analysis, an innovative procedure is proposed that divides the structure into linear and nonlinear parts and analyzes them separately. The proposed method satisfies the equilibrium and compatibility by establishing and solution of a set of nonlinear equations. The optimization problem employs the sizes of members, initial cable tensions and the positions of anchor on the ground and tie level of cables on the mast as design variables. To facilitate the optimization solution, a compatible sensitivity analysis procedure is proposed. Sensitivities of objective function, displacement and strength constraints in the mast and cables, subjected to a variety of load combinations including dead, wind and ice loads are calculated. Numerical examples are provided to show the nonlinear analysis procedure and the applicability of the algorithm to optimum design of practical guyed masts. 相似文献
197.
198.
S. Masoud Nabavizadeh Hashem Amini Fatemeh Jame Sedigheh Khosraviolya Hamid R. Shahsavari Fatemeh Niroomand Hosseini Mehdi Rashidi 《Journal of organometallic chemistry》2012
New cyclometalated platinum(II) complexes [PtMe(C^N)L], 1, in which C^N = deprotonated 2-phenylpyridine (ppy), benzo[h]quinoline (bhq) or 2-(p-tolyl)pyridine (tpy) and L = PPh3 or PMePh2, were synthesized by the reaction of [PtMe(C^N)(SMe2)] with 1 equiv of L. The reaction of complexes 1 with MeI gave the cyclometalated Pt(IV) complexes [PtMe2I(C^N)L], 3. On the basis of kinetic studies, using Uv–visible spectroscopy, it was suggested that the latter oxidative addition reactions were proceeded by an SN2 mechanism. The rates of the reactions at different temperatures were measured and consistent with the proposed mechanism, large negative ΔS3 values were found for each reaction. Besides, rate of reactions (in CHCl3) involving the PPh3 complexes [PtMe(C^N)(PPh3)], were almost 3–5 times slower than those involving the PMePh2 complexes [PtMe(C^N)(PMePh2)]. This was attributed to the electronic and steric effects of PPh3 ligand as compared with that of PMePh2 ligand which was further confirmed using density functional theory (DFT) calculations through finding approximate structures for the described complexes. 相似文献
199.
Concentration of biological specimens that are extremely dilute in a solution is of paramount importance for their detection. Microfluidic chips based on insulator-based DEP (iDEP) have been used to selectively concentrate bacteria and viruses. iDEP biochips are currently fabricated with glass or polymer substrates to allow for high electric fields within the channels. Joule heating is a well-known problem in these substrates and can lead to decreased throughput and even device failure. In this work, we present, for the first time, highly efficient trapping and separation of particles in DC iDEP devices that are fabricated on silicon using a single-etch-step three-dimensional microfabrication process with greatly improved heat dissipation properties. Fabrication in silicon allows for greater heat dissipation for identical geometries and operating conditions. The 3D fabrication allows for higher performance at lower applied potentials. Thermal measurements were performed on both the presented silicon chips and previously published PDMS devices comprised of microposts. Trapping and separation of 1 and 2 μm polystyrene particles was demonstrated. These results demonstrate the feasibility of high-performance silicon iDEP devices for the next generation of sorting and concentration microsystems. 相似文献
200.
Masoud Salavati-Niasari Mahnaz Dadkhah Mohammad Reza Nourani Alireza Amini Fazl 《Journal of Cluster Science》2012,23(4):1011-1017
A simple thermal decomposition route has been developed to prepare single-phase cubic ZrO2 nanospheres by [Zr(sal)3(H2O)2](NO3) as the new precursor. The ZrO2 nanocrystals have been prepared by bis-aqua, tris-salicylaldehydato zirconium(IV) nitrate; [Zr(sal)3(H2O)2](NO3), as precursor in oleylamine (C18H37N) and triphenylphosphine (C18H15P). To control the particle size, combination of C18H37N and C18H15P were applied as surfactants. The C18H37N and C18H15P play an important role in preventing aggregation of ZrO2 nanocrystals. The products were characterized by X-ray diffraction, transmission electron microscopy, photoluminescence spectroscopy, and Fourier transform infrared (FT-IR) spectroscopy to depict the phase and morphology. The FT-IR spectrum showed the purity of obtained ZrO2 nanocrystals with cubic phase. 相似文献