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1.
Nek M. Shaikh S. Hafeez M.A. Baig 《Spectrochimica Acta Part B: Atomic Spectroscopy》2007,62(12):1311-1320
We report the measurement of the zinc and cadmium plasma parameters produced by the fundamental, second, and third harmonics of the neodymium-doped yttrium aluminium garnet laser. The excitation temperature has been determined from the Boltzmann plot method, whereas the electron number density is estimated from the Stark broadened profile of several spectral lines. The temporal evolution of the plasma has also been investigated. Besides, we present experimental relative transition probabilities of the Zn (4s5s 3S1 → 4s4p 3P0,1,2) and Cd (5s6s 3S1 → 5s5p 3P0,1,2) triplets and compare our data with that listed in the National Institute of Standards and Technology database. The experiments have been performed in air but also in He, Ne and Ar atmosphere to study the effects of ambient gas environment on the emission intensity of the atomic and ionic lines and on the plasma parameters. 相似文献
2.
Soluble in organic solvent polyaniline (PANI) was prepared using DBSA as a functional dopant. Miscibility was maximized for
PMMA with hydroquinone. Transmission electron micrographs showed lowest level of phase separation. Thermal studies by differential
scanning calorimetry show some peak shifts which indicate the miscibility of two polymers. The formations of new bonds are
also confirmed by Fourier transformation infrared spectroscopy. Electroconductivity increased with increase of content of
doped PAN1, showing percolation threshold at 3 wt %. 相似文献
3.
In this paper the stability of motion of a symmetric satellite-gyrostat, with Visco-elastic square plate attached to it, around the center of mass in a circular orbit under a central gravitational field is studied. The gyrostat has a rotor oriented inside it such that the rotor becomes dynamically as well as statically stable with respect to the whole system. A study of the stability of this system has been done by using the method of separation of motion and averaging. Furthermore, we have solved the problem where there is no rotor. 相似文献
4.
The kinetic theory of plasma has been employed to compute the test-charge potential distributions accounting for quantization effects in magnetized electron-positron-ion (EPI) plasmas. In this regard, the degenerate positrons and electrons are assumed to follow the Fermi-Dirac distribution, while inertial ions are modelled by Maxwellian velocity distribution. By solving the Fourier-transformed Vlasov–Poisson equations, a modified dielectric function and electrostatic potential is obtained. By imposing various constraints on the test-charge speed, the potential profile has been analysed in terms of Debye–Hückel (DH), far-field (FF), and wake-field (WF) potentials. It has been found that the amplitude of DH and FF potentials increases by the inclusion of quantization effects, and it becomes the opposite for the WF potential profile. Furthermore, the variation of positron concentration significantly affects the DH, FF, and WF potentials. The present findings are important to understand the shielding phenomenon in degenerate multi-species plasmas. 相似文献
5.
Samples of Sn4+-substituted bismuth vanadate, formulated as Bi4Sn x V2? x O11?( x /2)? δ in the composition range 0.07 ≤ x ≤ 0.30, were prepared by standard solid-state reactions. Sample characterization and the principal phase transitions (α ? β, β ? γ and γ′ ? γ) were investigated by FT-IR spectroscopy, X-ray powder diffraction, differential thermal analysis (DTA) and AC impedance spectroscopy. For composition x = 0.07, the α ? β and β ? γ phase transitions were observed at temperatures of 451 and 536°C, respectively. DTA thermograms and Arrhenius plots of conductivities revealed the γ′ ? γ phase transition at 411 and 423°C for x = 0.20 and 0.30, respectively. AC impedance plots showed that conductivity is mainly due to the grain contribution, which is evident in the enhanced short-range diffusion of oxide ion vacancy in the grains with increasing temperature. The highest ionic conductivity (5.03 × 10?5 S cm?1 at 300°C) was observed for the x = 0.17 solid solution with less pronounced thermal hysteresis. 相似文献
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7.
Bushra Hafeez Kiani Nazif Ullah Ihsan-ul Haq Bushra Mirza 《Arabian Journal of Chemistry》2019,12(8):2644-2654
The rol genes have been shown to enhance the production of secondary metabolites in plants. This report examines the effect of trans-genes (rol ABC) on possible high production of biologically important phytochemicals and enhanced pharmacological activities. Three transgenic lines (1, 2 and 3) of Artemisia dubia WALL (transformed with Agrobacterium tumefaciens harboring rol ABC genes) were subjected to phytochemical analysis and pharmacological studies. A great variation in phytochemistry and the pharmacological activities was observed not only between the transgenic and non-transgenic control plants but also among the transgenic lines itself. Comparative chemical profile obtained via HPLC, TLC and spectrophotometry showed high degree of variations in the quantity of phytochemicals. An increased production of total flavonoids (71.1% in transgenic line 2) and total phenolics (110.8% in transgenic line 1), increase in caffeic acid and catechin and a decrease in gallic acid content in the extracts of transformed plants compared to the untransformed control plants was decreased. In case of pharmacological activities, moderate to high level increase in antimicrobial (antibacterial and antifungal) activities, cytotoxicity (14.1%), antitumor (29%) and antioxidant activities (23.9%) was observed (in transgenic line 2). In general all the three transgenic lines under study showed improvement in their pharmacological activities in the order of transgenic line 2 > 1 > 3 > control. The implication of these findings will help to meet the increasing demand of pharmacologically important compounds. 相似文献
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9.
Md Mushtaque Fernando Avecilla Zubair Bin Hafeez Mohammad Moshahid A. Rizvi 《Journal of heterocyclic chemistry》2019,56(6):1794-1805
Scaffolds containing one or more heteroatoms are ubiquitous in nature and are responsible for almost every biological processes in flora and fauna. The fact that heterocyclic cores have high propensity for biological targets, several nitrogen, oxygen, and sulfur‐containing heterocyclic compounds have been reported in the last few decades. One such intriguing class is 4‐thiazolidinone that exhibit diverse range of pharmacological activities. In the present study, we report synthesis, characterization, molecular docking, and anticancer evaluation of 10 new 4‐thiazolidinone analogues ( 5 – 14 ). One of the compounds ( 11 ) was structurally characterized using single crystal X structure. Anticancer evaluation against hepatocellular carcinoma cell line (HepG2) revealed that compound ( 7 ) was the most potent (IC50 = 75 μM) while other showed moderate to low activity (85–530 μM). To underpin the druggability and possible modes of action, drug‐likeness was determined and docking studies were carried out against β‐carbonic anhydrase receptor (PDB ID: 3IA). Attempts have also been made to establish a structure–activity relationship of the reported compounds. 相似文献
10.
N. M. Shaikh S. Hafeez B. Rashid M. A. Baig 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(2):371-379
In the present work, we have studied the spatial evolution of the aluminum
plasma produced by the fundamental (1064 nm), second (532 nm) and third (355
nm) harmonics of a Q-switched pulsed Nd:YAG laser. The experimentally
observed line profiles of neutral aluminum have been used to extract the
excitation temperature using Boltzmann plot method whereas the electron
number density has been determined from the Stark broadened profiles.
Besides we have studied the variation of excitation temperature and electron
number density as a function of laser irradiance at atmospheric pressure. In
addition, we have performed quantitative analysis of photon absorption and
vapor ionization mechanism at three laser wavelengths and estimated the
inverse bremsstrahlung (IB) absorption and photoionization (PI) coefficients.
The validity of the assumption of local thermodynamic equilibrium is
discussed in the light of the experimental results. 相似文献