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排序方式: 共有290条查询结果,搜索用时 15 毫秒
281.
A.F. Jalbout Ali Jameel Hameed Medhat Ibrahim 《Journal of organometallic chemistry》2008,693(2):216-220
In this work we have considered a series of 10 chalcanthrenes-fullerene complexes that were studied by the BLYP density functional theory (DFT) approach. A complete series of chalcanthrenes (C12H8XY, in which X, Y = O, S, Se, Te) where computed in several combinations in order to demonstrate the effect of structural changes on the electronic properties of the complexes under consideration. The optimized geometries, dissociation energies, and vibrational spectra of the chalcanthrenes-fullerene complexes are reported. 相似文献
282.
Meera Moydeen Abdul Hameed Syed Ali Padusha Mohamed Khan Badr M. Thamer Nirmala Rajkumar Hany El-Hamshary Mohamed El-Newehy 《先进技术聚合物》2023,34(1):6-23
Electrospinning procedures such as blend electrospinning, coaxial electrospinning, and emulsion electrospinning have been used for the fabrication of electrospun nanofibers (ENFs) for biomedical applications. These ENFs are attracted great interest especially in drug delivery applications due to their small size, high surface area-to-volume, and porosity. The aim of this review is to focus on the controlled release mechanism among the different electrospinning methods, and the selectivity of hydrophilic, water-soluble polymers as a carrier for drug. The mechanism for the drug delivery depends mainly on the method of drug loading, polymeric interactions, and the nature of polymer swelling, erosion, or degradation. This review compressed on the literature survey about the fabrication of nanofibers by different electrospinning methods, factors affecting the nanofiber morphologies, selectivity of polymeric blends for successful controlled release behavior, and the mechanism involved in the drug release steps. 相似文献
283.
ABSTRACT: BACKGROUND: Benzimidazole derivatives are structurally bioisosteres of naturally occurring nucleotides, which makes them compatible with biopolymers of living systems. This property gives benzimidazole a biological and clinical importance. In the last decade, this class of compounds has been reported to possess anti-allergic, anti-diabatic, anti-HIV, anti-hypertensive, anti-inflammatory, anti-mycobacterial, anti-oxidant, anti-protozoal, and anti-viral properties. The researchers are now interested to explore their potential as anti-cancer agents. In the present study, an effort was made to further explore this area of research. Furthermore, in order to increase the solubility and efficacy of these heterocycles, the interest is now shifted to the salts of these compounds. With this background, we planned to synthesize a series of meta-xylyl linked bis-benzimidazolium salts to assess their anti-proliferation efficacy on human colon cancer cell line (HCT 116). RESULTS: A number of N-alkylbenzimidazoles were synthesized by reactions of benzimidazole with alkyl halides (i-PrBr, PrBr, EthBr, Pent-2-ylBr, BuBr, BenzCl, HeptBr). The subsequent treatment of the resulting N-alkylbenzimidazoles with 1,3-(bromomethylene)benzene afforded corresponding bis-benzimidazolium salts. All synthesized compounds were characterized by spectroscopic techniques (Additional file 1: NMR & FT-IR) and microanalysis. Molecular structures of selected compounds were established through single crystal x-ray diffraction studies. All the compounds were assessed for their anti-proliferation test on human colorectal cancer cell line (HCT 116). Results showed that the compounds exhibited dose dependent cytotoxicity towards the colon cancer cells with IC50 ranges between 0.1 to 17.6 muM. The anti-proliferation activity of all compounds was more pronounced than that of standard reference drug 5-flourouracil (IC50 =19.2 muM). CONCLUSIONS: All the synthesized bis-benzimidazolium salts showed potential anticancer activity. Out of them, some of these salts showed IC50 value as low as 0.1-0.2 muM. Based on the results it can be concluded that, the bis-benzimidazolium salts could probably be the potential source of chemotherapeutic drugs. 相似文献
284.
Chaudhry AA Haque S Kellici S Boldrin P Rehman I Khalid FA Darr JA 《Chemical communications (Cambridge, England)》2006,(21):2286-2288
Nano-particle hydroxyapatite (HA) rods, were rapidly synthesised using a three pump continuous hydrothermal process (using a water feed at up to 400 degrees C and at 24 MPa): the product was obtained as a highly crystalline and phase pure material, without the need for an ageing step or subsequent heat treatment. 相似文献
285.
S. K. Samanta U. C. Gupta M. L. Chaudhry 《4OR: A Quarterly Journal of Operations Research》2009,7(4):337-361
This paper considers a single-server queueing model with finite and infinite buffers in which customers arrive according to
a discrete-time renewal process. The customers are served one at a time under discrete-time Markovian service process (D-MSP).
This service process is similar to the discrete-time Markovian arrival process (D-MAP), where arrivals are replaced with service
completions. Using the imbedded Markov chain technique and the matrix-geometric method, we obtain the system-length distribution
at a prearrival epoch. We also provide the steady-state system-length distribution at an arbitrary epoch by using the supplementary
variable technique and the classical argument based on renewal-theory. The analysis of actual-waiting-time (in the queue)
distribution (measured in slots) has also been investigated. Further, we derive the coefficient of correlation of the lagged
interdeparture intervals. Moreover, computational experiences with a variety of numerical results in the form of tables and
graphs are discussed. 相似文献
286.
Yetta Eagleman Marvin Weber Anurag Chaudhry Stephen Derenzo 《Journal of luminescence》2012,132(11):2889-2896
X-ray excited emission spectra, photoluminescence excitation and emission spectra, optical reflectivity spectra, and pulsed X-ray and optical excited luminescence decay measurements are reported for cerium-doped La2Hf2O7 powders prepared by solid state synthesis. A broad luminescence associated with oxygen vacancies is observed in the region 350–750 nm with a peak around 460 nm. The photoluminescence spectra and the number of oxygen vacancies vary for samples annealed in oxidizing or reducing atmospheres and with the temperature of the synthesis process. Increasing the cerium concentration reduces the oxygen-vacancy-related emission due to the presence of Ce4+. First principles calculations predict that Ce4+ can substitute in Hf sites; this is confirmed from the optical reflectivity spectrum of cerium-doped La2Hf2O7. Photoluminescence excitation and emission spectra characteristic of Ce4+ charge transfer transitions and possibly Ce3+ are also observed. Although trivalent cerium may be present, no emission observed from cerium-doped La2Hf2O7 can be attributed to Ce3+ in La sites. 相似文献
287.
The kinetics of the oxidation of malachite green (MG+) by Fe(III) were investigated spectrophotometrically by monitoring the absorbance change at 618 nm in aqueous and micellar media at a temperature range 20–40 °C; I = 0.10 mol dm?3 for [H+] range (2.50–15.00) × 10?4 mol dm?3. The rate of reaction increases with increasing [H+]. The reaction was carried out under pseudo-first-order conditions by taking the [Fe(III)] (>10-fold) the [MG+]. A mechanism of the reaction between malachite green and Fe(III) is proposed, and the rate equation derived from the mechanism was consistent with the experimental rate law as follows: Rate = (k 4 + K 1 k 5[H+]) [MG+][Fe(III)]. The effect of surfactants, such as cetyltrimethylammonium bromide (CTAB, a cationic surfactant) and sodium dodecylsulfate (SDS, an anionic surfactant), on the reaction rate has been studied. CTAB has no effect on the rate of reaction while SDS inhibits it. Also, the effect of ligands on the reaction rate has been investigated. It is proposed that electron transfer proceeds through an outer-sphere mechanism. The enthalpy and the entropy of the activation were calculated using the transition state theory equation. 相似文献
288.
M. Saleem A. Hameed M. J. Iqbal M. A. Baig 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,55(1):121-126
The ionic species present in the laser ablated plume from the surface of the Bi1.6Pb0.4Sr2Ca2Cu3Oysuperconducting target have been investigated using a non-commercial laboratory developed linear time-of-flight (TOF) mass
spectrometer. The recorded TOF mass spectra reveal the presence of all the atomic species of the target material, monoxide
and cluster ions. The occurrence of clusters in the mass spectra is the evidence of aggregation processes at higher laser
fluence. The dependence of the ionic yield of the species has been studied using the fundamental (1064 nm), second harmonic
(532 nm) and fourth harmonic (266 nm) of a Nd:YAG laser. The maximum ionization of the species present in the plume is observed
at 266 nm even at lower laser fluence. The effect of the laser fluence on the total and individual ionic yields of the ablated
species is also presented. 相似文献
289.
290.