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11.
12.
Rosa Pereira Tommy Julianto Peh-Kim Ang Sharon Sheue-Nee Ling Carlos Mauricio Barbosa Kah-Hay Yuen Abu Bakar Abdul Majeed 《Chromatographia》2010,71(5-6):373-381
A sensitive and rapid routine LC method was validated for measuring cefotaxime incorporated in three different pH-sensitive nanoparticles. The drug was chromatographed on a C18 reversed-phase column; the mobile phase used was 0.05 M aqueous ammonium acetate, acetonitrile and tetrahydrofuran (87:11:2, v/v) adjusted to pH 5.5 with acetic acid. The flow rate was 1 mL min?1 and cefotaxime was quantified at 254 nm, with a sensitivity range of 0.005 AUFS. The validated method was specific, linear (R 2 ≥ 0.999), precise and accurate in a concentration range of 0.2–50.0 μg mL?1. The method was rapid, selective and suitable for evaluation of cefotaxime in pH-sensitive Eudragit nanoparticles. 相似文献
13.
Asma Rehman Muhammad Irfan Majeed Ayesha Ihsan Syed Zajif Hussain Saif-ur-Rehman Muhammad Afzal Ghauri Zafar M. Khalid Irshad Hussain 《Journal of nanoparticle research》2011,13(12):6747-6754
Abstract
A simple and environmentally benign green method is reported to decorate growing fungal hyphae with high loading of gold nanoparticles, which were initially produced using aqueous tea extract as a sole reducing/stabilizing agent. Inoculation of fungal spores in aqueous suspension of nanoparticles led to the growth of intensely red-coloured fungal hyphae due to the accumulation of gold nanoparticles. Heat treatment of these hybrid materials led to the formation of porous gold microwires. This report is thus an interesting example of using green and sustainable approach to produce nanostructured materials which have potential applications in catalysis, sensing and electronics. 相似文献14.
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16.
A visco-elastoplastic model for the impact between a compact body and a composite target is presented. The model is a combination
of a nonlinear contact law that includes energy loss due to plastic deformation and a viscous element that accounts for energy
losses due to wave propagation and/or damping. The governing nonlinear equations are solved numerically to obtain the response.
A piecewise linear version of the model is also presented, which facilitates analytical solution. The model predictions are
compared to those of the well-known and commonly used Hunt–Crossley model. The effects of the various impact parameters, such
as impactor mass, velocity, plasticity, and damping, on the impact response and coefficient of restitution are investigated.
The model appears to be suitable for a wide range of impact situations, with parameters that are well defined and easily calculated
or measured. Furthermore, the resulting coefficient of restitution is shown to be a function of impact velocity and damping,
as confirmed by published experimental data. 相似文献
17.
Yongqi Wang Tasawar Hayat Abdul Majeed Siddiqui 《Mathematical Methods in the Applied Sciences》2005,28(3):329-347
The present investigation deals with an undulating surface model for the motility of bacteria gliding on a layer of non‐Newtonian slime. The slime being the viscoelastic material is considered as a power‐law fluid. A hydrodynamical model of motility involving an undulating cell surface which transmits stresses through a layer of exuded slime to the substratum is examined. The non‐linear differential equation resulting from the balance of momentum and mass is solved numerically by a finite difference method with an iteration technique. The manner in which the various exponent values of the power‐law flow affect the structure of the boundary layer is delineated. A comparison is made of the power‐law fluid with the Newtonian fluid. For the power‐law fluid with respect to different power‐law exponent values, shear‐thinning and shear‐thickening effects can be observed, respectively. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
18.
We discuss the notion of spin squeezing considering two mutually exclusive classes of spin-s states, namely, oriented and non-oriented states. Our analysis shows that the oriented states are not squeezed while non-oriented
states exhibit squeezing. We also present a new scheme for construction of spin-s states using 2s spinors oriented along different axes. Taking the case of s=1, we show that the ‘non-oriented’ nature and hence squeezing arise from the intrinsic quantum correlations that exist among
the spinors in the coupled state. 相似文献
19.
Kathleen A. Williams Matthew Magnuson Waqas Majeed Stephen M. LaConte Scott J. Peltier Xiaoping Hu Shella D. Keilholz 《Magnetic resonance imaging》2010
Functional connectivity measures based upon low-frequency blood-oxygenation-level-dependent functional magnetic resonance imaging (BOLD fMRI) signal fluctuations have become a widely used tool for investigating spontaneous brain activity in humans. Still unknown, however, is the precise relationship between neural activity, the hemodynamic response and fluctuations in the MRI signal. Recent work from several groups had shown that correlated low-frequency fluctuations in the BOLD signal can be detected in the anesthetized rat — a first step toward elucidating this relationship. Building on this preliminary work, through this study, we demonstrate that functional connectivity observed in the rat depends strongly on the type of anesthesia used. Power spectra of spontaneous fluctuations and the cross-correlation-based connectivity maps from rats anesthetized with α-chloralose, medetomidine or isoflurane are presented using a high-temporal-resolution imaging sequence that ensures minimal contamination from physiological noise. The results show less localized correlation in rats anesthetized with isoflurane as compared with rats anesthetized with α-chloralose or medetomidine. These experiments highlight the utility of using different types of anesthesia to explore the fundamental physiological relationships of the BOLD signal and suggest that the mechanisms contributing to functional connectivity involve a complicated relationship between changes in neural activity, neurovascular coupling and vascular reactivity. 相似文献
20.
M. A. Majeed?Khan M. Wasi?Khan Mansour Alhoshan M. S. AlSalhi A. S. Aldwayyan 《Applied Physics A: Materials Science & Processing》2010,100(1):45-51
Pure and Co-doped ZnO nanostructured samples have been synthesized by a chemical route. We have studied the structural and
optical properties of the samples by using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), field-emission
transmission electron microscope (FETEM), energy-dispersive X-ray (EDX) analysis and UV–VIS spectroscopy. The XRD patterns
show that all the samples are hexagonal wurtzite structures. Changes in crystallite size due to mechanical activation were
also determined from X-ray measurements. These results were correlated with changes in particle size followed by SEM and TEM.
The average crystallite sizes obtained from XRD were between 20 to 25 nm. The TEM images showed the average particle size
of undoped ZnO nanostructure was about 20 nm whereas the smallest average grain size at 3% Co was about 15 nm. Optical parameters
such as absorption coefficient (α), energy band gap (E
g
), the refractive index (n), and dielectric constants (σ) have been determined using different methods. 相似文献