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排序方式: 共有196条查询结果,搜索用时 31 毫秒
111.
M. A. Chaudhri Q. Nadeem M. N. Chaudhri Q. Jabbar 《Journal of Radioanalytical and Nuclear Chemistry》2007,271(3):697-700
By making use of the 19F(p,αγ)16O reaction the F-concentrations of different varieties of tea leaves, of some international geochemical reference materials,
and of the bones and teeth of some experimental animals have been determined. The tea leaves from Ceylon (ordinary), Orange
Pekoe (special Ceylon), China (ordinary black), Lapsang Souchong (special smoked Chinese) and Darjeeling (India) were found
to contain 170 ppm, 170 ppm, 120 ppm, 160 ppm and 100 ppm of fluorine, respectively, The F-concentrations of established geochemical
reference materials, NIM-D, NIM-N, NIM-P and NIM-S, from the National Institute of Metallurgy, South Africa were determined
to be 60 ppm, 120 ppm, 130 ppm and 190 ppm, respectively. The bones of rabbits, who were given fluoridated water, were found
to contain much higher amount of fluorine than the bones of the control rabbit. Furthermore, the rabbits who were kept on
fluoridated water for 45 days, had almost double the amount of F in their bones than the rabbits who were given fluoridated
water for only 15 days. Similarly, the teeth of grown-up monkeys who were given fluoridated water since birth had double the
amount of fluorine than those of the control monkey. 相似文献
112.
Ali M Nasir S Nguyen QH Sahoo JK Tahir MN Tremel W Ensinger W 《Journal of the American Chemical Society》2011,133(43):17307-17314
Here we demonstrate a novel biosensing platform for the detection of lactoferrin (LFN) via metal-organic frameworks, in which the metal ions have accessible free coordination sites for binding, inside the single conical nanopores fabricated in polymeric membrane. First, monolayer of amine-terminated terpyridine (metal-chelating ligand) is covalently immobilized on the inner walls of the nanopore via carbodiimide coupling chemistry. Second, iron-terpyridine (iron-terPy) complexes are obtained by treating the terpyridine modified-nanopores with ferrous sulfate solution. The immobilized iron-terPy complexes can be used as recognition elements to fabricate biosensing nanodevice. The working principle of the proposed biosensor is based on specific noncovalent interactions between LFN and chelated metal ions in the immobilized terpyridine monolayer, leading to the selective detection of analyte protein. In addition, control experiments proved that the designed biosensor exhibits excellent biospecificity and nonfouling properties. Furthermore, complementary experiments are conducted with multipore membranes containing an array of cylindrical nanopores. We demonstrate that in the presence of LFN in the feed solution, permeation of methyl viologen (MV(2+)) and 1,5-naphthalenedisulphate (NDS(2-)) is drastically suppressed across the iron-terPy modified membranes. On the basis of these findings, we envision that apart from conventional ligand-receptor interactions, the designing and immobilization of alternative functional ligands inside the synthetic nanopores would extend this method for the construction of new metal ion affinity-based biomimetic systems for the specific binding and recognition of other biomolecules. 相似文献
113.
Exact solutions for the flow of second grade fluid in annulus between torsionally oscillating cylinders 总被引:1,自引:0,他引:1
The velocity field and the associated shear stress corresponding to the torsional oscillatory flow of a second grade fluid, between two infinite coaxial circular cylinders, are determined by means of the Laplace and Hankel transforms. At time t = 0, the fluid and both the cylinders are at rest and at t = 0 + , cylinders suddenly begin to oscillate around their common axis in a simple harmonic way having angular frequencies ω 1 and ω 2 . The obtained solutions satisfy the governing differential equation and all imposed initial and boundary conditions. The solutions for the motion between the cylinders, when one of them is at rest, can be obtained from our general solutions. Furthermore, the corresponding solutions for Newtonian fluid are also obtained as limiting cases of our general solutions. 相似文献
114.
S. U. Rahman Matiullah F. Malik M. Rafique J. Anwar M. Ziafat A. Jabbar 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(2):647-655
Soil samples were collected from different localities of districts Jhelum, Chakwal, Rawalpindi and Attock, Punjab Province,
Pakistan with an aim to measure naturally occurring radionuclides, namely 226Ra, 232Th, 40K and fallout 137Cs radionuclide using a P-type coaxial high purity germanium (HPGe) γ-ray spectrometer. Measured specific activities of 226Ra, 232Th and 40K in these soil samples ranged from 26.02 ± 7.11 to 93.54 ± 8.13 Bq kg−1, 29.34 ± 2.58 to 114.41 ± 2.80 Bq kg−1 and 348.15 ± 3.20 to 752.98 ± 4.20 Bq kg−1, respectively. Activity due to 137Cs was observed in some locations which ranged from 0.4 ± 0.2 to 7.8 ± 0.3 Bq kg−1. From the measured activity concentrations, radium equivalent activity concentrations were determined followed by calculations
of mean absorbed dose rate and mean annual effective dose for the inhabitants of the studied area. The mean radium equivalent
activity, internal and external hazard indices values came out to be 179.26 ± 11.93 Bq kg−1, 0.64 ± 0.05 and 0.48 ± 0.03, respectively. Indoors and outdoor average annual effective dose values were found to be 0.42 ± 0.03
and 0.10 ± 0.01 mSv, respectively. Present data have been compared with the published data for other parts of the world and
found to be safe for public and environment. 相似文献
115.
Sohaib?A.?QaziEmail author Abeera?Saeed Saima?Nasir Hammad?Omer 《Applied magnetic resonance》2017,48(5):461-471
Parallel magnetic resonance imaging (pMRI) and compressed sensing (CS) have been recently used to accelerate data acquisition process in MRI. Matrix inversion (for rectangular matrices) is required to reconstruct images from the acquired under-sampled data in various pMRI algorithms (e.g., SENSE, GRAPPA) and CS. Singular value decomposition (SVD) provides a mechanism to accurately estimate pseudo-inverse of a rectangular matrix. This work proposes the use of Jacobi SVD algorithm to reconstruct MR images from the acquired under-sampled data both in pMRI and in CS. The use of Jacobi SVD algorithm is proposed in advance MRI reconstruction algorithms, including SENSE, GRAPPA, and low-rank matrix estimation in L + S model for matrix inversion and estimation of singular values. Experiments are performed on 1.5T human head MRI data and 3T cardiac perfusion MRI data for different acceleration factors. The reconstructed images are analyzed using artifact power and central line profiles. The results show that the Jacobi SVD algorithm successfully reconstructs the images in SENSE, GRAPPA, and L + S algorithms. The benefit of using Jacobi SVD algorithm for MRI image reconstruction is its suitability for parallel computation on GPUs, which may be a great help in reducing the image reconstruction time. 相似文献
116.
Polyether ether ketone (PEEK) is a semi-crystalline thermoplastic polymer having excellent mechanical and thermal properties. Exposure of this polymer to aliphatic and aromatic solvents can lead to degradation or swelling of the polymeric material. The present work described the plasticization and stability analysis of semi-crystalline PEEK under different aromatic and aliphatic solvent environment. A variety of solvents (acetone, benzene, benzyl alcohol, chloroform, methanol, and toluene), based on their Hildebrand’s Solubility Parameter, were chosen for investigation. The physico-chemical characteristics of virgin and treated polymeric samples were investigated using Gas Chromatography–Mass Spectrometry (GC–MS), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), and Fourier Transform Infrared Spectroscopy (FTIR) techniques. The results indicated that the solvent exposure did not significantly affect the thermal behavior and chemical structure of the polymer. However, it seems that certain components of the polymer were leached into the solvent phase as revealed by the GC–MS analysis. The present study identified PEEK as a potentially suitable polymer for the applications where high resistance to aliphatic and aromatic solvents is needed. 相似文献
117.
Amrah Nouri Ahmad Poursattar Marjani Jabbar Khalafy 《Journal of heterocyclic chemistry》2019,56(10):2912-2921
A new series of benzo[g]thiazolo[2,3‐b]quinazolin‐4‐ium and benzo[g]benzo[4,5]thiazolo[2,3‐b]quinazolin‐14‐ium hydroxide derivatives have been synthesized by the one‐pot, three‐component reaction of aryl glyoxal monohydrates, 2‐hydroxy‐1,4‐naphthoquinone, and 2‐aminothiazole or 2‐aminobenzothiazole in the presence of triethylamine and p‐toluenesulfonic acid as organocatalysts in H2O/acetone (2:1) at room temperature. This method offers mild reaction conditions, excellent yields, easy workup, and readily accessible starting materials and catalysts. 相似文献
118.
Microwave-assisted catalytic oxidative desulfurization of gasoil fuel using synthesized CuO-ZnO nanocomposites 《燃料化学学报》2019,47(9):1075-1082
Recently,organosulfur removal from liquid petroleum fuels is very significant aspect of environment protecting and fuel cell requests.Therefore,improved approaches to remove sulfur are still essential.In the present work,a simple catalytic oxidative desulfurization(CODS)system for Iraqi gasoil fraction has been successfully developed using CuO-ZnO nanocomposites as catalysts,and H_2O_2 as oxidant under microwave irradiation.The main reaction parameters influencing sulfur conversion including microwave power,irradiation time,catalyst dosage and H_2O_2 to gasoil volume ratio have been investigated.The CuO-ZnO nanocomposites was synthesized with different weight ratios and characterized by XRD,FE-SEM,AFM and BET surface area methods.The results reveal that,high sulfur conversion(93%)has been achieved under suitable conditions of microwave CODS as follows:microwave power of 540 W,irradiation time of 15 min,catalyst dosage of 8 g/L(0.4 g),and H_2O_2:gasoil volume ratio of 0.3.The catalyst reusability shows that the synthesized catalyst can be reused five times without an important loss in its activity. 相似文献
119.
Saima Arshed Anjan Biswas Mahmoud Abdelaty Qin Zhou Seithuti P. Moshokoa Milivoj Belic 《Chinese Journal of Physics (Taipei)》2018,56(6):2879-2886
This paper employs two integration procedures to obtain soliton solutions to the perturbed Gerdjikov–Ivanov equation. They are G′/G2–expansion method and the sine–cosine method. Bright, dark and singular solitons are revealed along with a few of the combo–soliton solutions. The existence criteria of these solitons are also given. 相似文献
120.
In this paper, two integrating strategies namely exp[-Φ(X)] and G'/G~2-expansion methods together with the attributes of local-M derivatives have been acknowledged on the electrical microtubule(MT) model to retrieve soliton solutions. The said model performs a significant role in illustrating the waves propagation in nonlinear systems. MTs are also highly productive in signaling, cell motility, and intracellular transport. The proposed algorithms yielded solutions of bright, dark, singular, and combo fractional soliton type. The significance of the fractional parameters of the fetched results is explained and presented vividly. 相似文献