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271.
Ziaur Rahman Shakeel ur Rehman Sikander M. Mirza Waheed Arshed Nasir M. Mirza Muhammad Masood 《Radiation measurements》2012,47(6):406-409
Due to worldwide use of I-131 for the treatment of benign and malignant thyroid diseases, reliable dose estimation for various thyroid mass values is necessary. In this study computation of the radiation absorbed dose due to β- and γ-activity of I-131 to thyroid has been carried out using the GEANT4 code for water, ICRP and ICRU soft tissues simulating thyroid tissue. The results are validated by comparison with the MIRD calculations. The effect of size and shape of thyroid on absorbed dose has also been studied by varying the volume of thyroid in 10–150 cm3 range and by using spherical and cylindrical models for thyroid. Experimental measurements have also been performed using a group of 20 patients, who were treated for thyro-toxicosis with I-131. Dose equivalent was measured with a portable ionization chamber after the administration of 405–851 MBq of I-131. Comparison of peak energy and effective energy per transformation with the MIRD has been performed yielding only 0.5% relative differences between these two energies. For spherical model, the relative difference of peak and effective energies with the MIRD is 5.2% and 4.7% respectively and very similar for cylindrical models. Spherical model shows 0.45% increase as compared to that of cylindrical model. The use of water, ICRP or ICRU materials only implies negligible difference. Total energy deposition per decay of I-131 increases with volume for both models. The estimated results of spherical and cylindrical thyroid models show an excellent agreement with the corresponding the MIRD results. Simulated results for ambient dose equivalent rate show a good agreement with our experiment and corresponding errors remain less than 13% in the case of dose at 1 m, and are less than 8% for doses at the neck surface. 相似文献
272.
A. Rauf F. Ahmed A. M. Qureshi Aziz‐ur‐Rehman A. Khan M. I. Qadir M. I. Choudhary Z. H. Chohan M. H. Youssoufid T. Ben Haddad 《中国化学会会志》2011,58(4):528-537
Various novel barbituric and thiobarbituric acid derived sulphonamides were synthesized in excellent yield via three components single pot reaction; and these were screened for in vitro urease inhibition studies against jack bean urease. The compounds 1‐7 were found to exhibit a low to moderate activity whereas compounds 8‐14 showed a significant activity (88.3‐99.9% inhibition determined at 500 μM concentration). Structures of the synthesized compounds were confirmed by 1H‐NMR, 13C‐NMR, mass spectrometry and elemental analysis data. 相似文献
273.
In this paper, we discuss various techniques for solving the system of linear equations that arise from the discretization of the incompressible Stokes equations by the finite‐element method. The proposed solution methods, based on a suitable approximation of the Schur‐complement matrix, are shown to be very effective for a variety of problems. In this paper, we discuss three types of iterative methods. Two of these approaches use the pressure mass matrix as preconditioner (or an approximation) to the Schur complement, whereas the third uses an approximation based on the ideas of least‐squares commutators (LSC). We observe that the approximation based on the pressure mass matrix gives h‐independent convergence, for both constant and variable viscosity. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
274.
Tariq Mahmud Rabia Rehman Aqsa Gulzar Amina Khalid Jamil Anwar Umer Shafique Muhammad Salman 《Arabian Journal of Chemistry》2010,3(4):219-224
Complexes of enaminones; 4-N,N-diethylamine-pent-3-ene-2-one [HL1], 4-N,N-di n-propylamine-pent-3-ene-2-one [HL2] and 4-N,N-dicyclohexylamine-pent-3-ene-2-one [HL3] with Fe(II) and Zn(II) ions were prepared by reacting the equimolar ethanolic solutions of the ligands (HL1, HL2 and HL3) with ethanolic metal solutions. The complexes formed, were characterized by infrared, ultraviolet and atomic absorption spectroscopy. Ligands and their metal complexes were tested against Escherichia coli and Staphylococcus aureus bacteria to assess their antibacterial action using disc diffusion method. Ligands were completely inactive against bacteria whereas the complex Zn (HL1) has significant action on both bacteria, indicating that it has a good potential as bactericide. Other complexes have normal antiseptic character. 相似文献
275.
Hussain J Bukhari N Hussain H Rehman NU Hussain SM 《Natural product communications》2010,5(11):1785-1786
Phytochemical investigation of Nepeta distans Raul resulted in the isolation of a new phenolic compound, nepatanol (1), and eight known compounds, markhamioside F, netidiol, nepedinol, thymoquinone, eugenol, oleanolic acid, ursolic acid, and beta-sitosterol, which have been isolated for the first time from this source. Structures of all the isolates were established on the basis of MS, and 1D and 2D NMR spectral data and by comparison with reported data. 相似文献
276.
Peter A. Lieberzeit Abdul Rehman Naseer Iqbal Bita Najafi Franz L. Dickert 《Monatshefte für Chemie / Chemical Monthly》2009,391(8):947-952
Abstract An e-nose comprised of six sensing channels each coated with a molecularly imprinted polymer (MIP) selectively interacting
with alpha-pinene, thymol, estragol, linalool, and camphor, respectively, was designed. When applying it for continuous online
surveillance of terpenes emitted from basil and peppermint leaves as a criterion of freshness, it very appreciably reproduced
the emanation patterns from these plants as shown by GC-MS. Chromatography yielded a variety of terpenes in a concentration
range below 70 ppm. Trend lines obtained from the e-nose were corroborated by GC-MS and also appreciably fit the usual conduct
of these plants as observable by the human nose.
Graphical abstract
相似文献
277.
Some biologically important tin(Ⅳ) complexes derived from 5,5-diethyl sodium barbital have been synthesized and characterized through various analytical and spectroscopic techniques such as IR, ^1H-, ^13C-NMR and ^119mSn mossbauer. On the basis of these spectroscopic techniques, octahedral geometry has been assigned to all the novel compounds. These complexes, soluble in DMSO and DMF, were screened against a wide range of microorganisms. The results proved that the diphenyltin(Ⅳ) and dibutyltin(Ⅳ) complexes exhibit excellent activity against all types of microorganisms, while the rest of the compounds show significant activity that can be used during the biological study. 相似文献
278.
Study of Saudi Arabian climatic conditions using Hurst exponent and climatic predictability index 总被引:1,自引:0,他引:1
Shafiqur Rehman 《Chaos, solitons, and fractals》2009,39(2):499-509
This paper utilizes Hurst exponent to study the persistency of meteorological parameters individually and dependency of rainfall/precipitation on pressure and temperature using climate predictability index. For the purpose, daily averages of surface pressure and temperature and daily total rainfall data for a period of 7 years for three locations and 14 years for seven locations has been utilized. The Hurst exponents (H) for above mentioned meteorological parameters were calculated using rescaled range analysis (R/S) and absolute moments methods. These H values were used to calculate the fractal dimension D for pressure, temperature and rainfall data. Finally, these D’s were used to calculate the climate predictability index PIC in terms of pressure predictability index (PIP), temperature predictability index (PIT) and rainfall predictability index (PIR). The Hurst exponent analysis showed that H values for rainfall, relative humidity and wind speed time series data for all the stations were >0.5 which is indicative of persistence behavior of the parameters on the previous values while for pressure and temperature H values were <0.5 means anti-persistence behavior. The climate predictability index showed that in most of the cases the rainfall was dependent on both pressure and temperature predictability indices. In some cases it was more dependent on pressure index than the temperature and in some cases otherwise. In Saudi Arabia there is no prevalent or established rainy season and the present analysis could not result into concrete results. It is therefore recommended to analyze the data by breaking the entire data set into seasons and further into different years. 相似文献
279.
Javid Hussain Najeeb Ur Rehman Hidayat Hussain Liaqat Ali Ahmed Al‐Harrasi Viqar Uddin Ahmad 《Helvetica chimica acta》2011,94(11):2106-2110
The structure elucidation of two new phthalate derivatives named nepethalates A ( 1 ) and B ( 2 ) is reported. Both of these secondary metabolites were isolated from the MeOH extract of Nepeta clarkei. HR‐EI‐MS, IR and UV absorption spectrometry, and NMR experiments including COSY, HMQC, and HMBC were used for the determination of the structures and complete 1H‐ and 13C‐NMR assignments. 相似文献
280.
Hussain J Begum N Hussain H Khan FU Rehman NU Al-Harrasi A Ali L 《Natural product communications》2012,7(5):615-616
Phytochemical investigation of Ajuga bracteosa Wall ex Benth. (Labiatae) resulted in the isolation of a new phenolic compound, ajuganane (1) and three known compounds, 3,4'-dihydroxy-3,6,7-trimethoxyflavone, 7-hydroxy-3,6,3',4'-tetramethoxyflavone and ursolic acid. The structure of the new compound was elucidated by detailed spectroscopic (1H, 13C NMR, COSY, HMQC, HMBC), and HR-EI-MS analysis. 相似文献