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排序方式: 共有326条查询结果,搜索用时 62 毫秒
101.
Mayeen Uddin Khandaker Hiromitsu Haba Masashi Murakami Naohiko Otuka Hasan Abu Kassim 《Journal of Radioanalytical and Nuclear Chemistry》2014,302(2):759-764
Activation cross-sections of natCu(d,x)62,65Zn,64Cu,60g+mCo,59Fe reactions were measured using a stacked foil activation technique combined with HPGe gamma-ray spectrometry up to the deuteron energy of 24 MeV. Measured data were critically compared with the available literature data and theoretical data extracted from the TENDL-2012 library, and found only partial agreements among them. Cross-sections of natCu(d,x)59Fe reactions are reported here for the first time in the energy region of 19–23 MeV. Measured cross-sections of the long-lived 65Zn, 60gCo and 59Fe radionuclides are significant for understanding the activation behaviour of copper, an essential structural material used in accelerator and nuclear industry. 相似文献
102.
Anis Fadhlina Izyani Awang Qamar Uddin Ahmed Syed Adnan Ali Shah Juliana Md. Jaffri Kashif Ghafoor A. B. M. Helal Uddin 《Natural product research》2020,34(5):629-637
AbstractStereospermum fimbriatum or locally known as “Chicha” is traditionally used for itchy skin, earache, stomachache and postpartum treatments. This study was designed to evaluate the antimicrobial potential of S. fimbriatum’s stem bark against 11 pathogens and isolate its bioactive compound. Successive soxhlet extraction was conducted using n-hexane, dichloromethane (DCM) and methanol. Disc diffusion, minimum inhibitory and bactericidal concentration (MIC & MBC) assays were done to examine the antimicrobial activity. Bioassay-guided isolation was conducted on S. fimbriatum’s extract. The DCM extract of stem bark (DS) was the most potent extract followed by n-hexane extract of the stem bark (NS). A novel compound was isolated and coded as C1 which demonstrated potent antibacterial effects with the MIC values as low as 3.13?µg/mL to 6.25?µg/mL, against S. epidermidis, MRSA and S. aureus. Thus, S. fimbriatum could be a potential source of antimicrobial agents for the treatment of skin infections, specifically, MRSA. 相似文献
103.
Ghias Uddin Ala Ud Din Amna Khurshid Frederick A. Valeriote M. Iqbal Choudhary 《中国化学会会志》2013,60(1):92-96
The significant inhibition and selectivity for human solid tumor cell by oily fraction of Maytenus royleanus, was subjected to GC‐MS analysis for determination of its chemical constituents. GC‐MS profile of methyl ester derivatives of fatty acids, showed that Palmitic acid (35.41%), Oleic acid (10.91%), Stearic acid (5.31%), Margaric acid (5.13%), Behenic acid (5.18%) and Hexanoic acid (4.97%) were the major components in the isolated oily fraction, while rest of the other fatty acids were present in minor concentration. The literature revealed that no such work has been done for the determination of fatty acids in M. royleanus stem oil. 相似文献
104.
Ahmed Jalal Uddin Norihiro Katayama Yutaka Ohkoshi Yasuo Gotoh Masanobu Nagura 《Journal of Polymer Science.Polymer Physics》2002,40(21):2449-2462
For monofilament biodegradable sutures fabricated from the L ‐lactide–ε‐caprolactone (75/25) copolymer [P(LLA/CL)], there have been some concerns regarding their mechanical properties, such as the knot‐pull strength and stiffness. This article demonstrates the further potentiality of these sutures through improvements in those properties. With the aim of diminishing the molecular orientation, particularly in the suture surface region, we adopted an expedient method to treat P(LLA/CL) sutures with an acetone/water mixture, using different times and time patterns. The changes in the molecular orientation distributions across the suture cross sections were characterized by the specific index of birefringence measured with an interference microscope. The crystal orientations, knot‐pull strengths, tensile strengths, and bending rigidity were measured. The conformational changes in suture breaking during knot‐pull tests were analyzed with high‐speed‐video observations. Morphological analyses of the fractural surfaces were performed with scanning electron microscopy. The knot‐pull strength tended to rise, in comparison with that of untreated samples, up to a certain treatment time and was accompanied by a minimal decrement of the tensile strength. The knot‐pull strength did not show an increasing trend with further treatment, whereas the tensile strength declined remarkably. The birefringence, crystal orientation, bending rigidity, fractured surface analysis, and high‐speed‐video observations revealed molecular disorientation mainly in the filament outer layers for that particular treatment causing the sutures to be considerably softer. The suture softness played a role in changing the deformation behavior of the knot when a load was applied and caused the knot‐pull strength to rise. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2449–2462, 2002 相似文献
105.
We study the equilibrium configurations of a cosmic string described by the Nambu action in the NUT-Kerr-Newman spacetime which includes as special cases the Kerr-Newman black hole spacetime as well as the NUT spacetime which is considered as a cosmological model. In this study it is interesting to note that one can obtain parallel results for the Kerr-Newman black hole as well as the NUT spacetime. 相似文献
106.
Mohammad Nasir Uddin Victoria F. Samanidou Ioannis N. Papadoyannis 《Journal of separation science》2008,31(21):3704-3717
A simple, sensitive, selective, and reproducible RP‐HPLC method with DAD detection at 240 nm was developed for the determination of six 1,4‐benzodiazepines: bromazepam (BRZ), clonazepam (CLZ), diazepam (DZP), flunitrazepam (FNZ), lorazepam (LRZ), alprazolam (APZ); and two metabolites: α‐hydroxyalprazolam (HALZ) and α‐hydroxytriazolam (HTZL) in human plasma, urine, and saliva, using colchicine as internal standard, after SPE using Nexus Varian cartridges. Separation was performed on a Kromasil C8 (250 mm×5 mm, 5 μm) analytical column with a gradient mobile phase containing methanol, ACN and 0.05 M ammonium acetate. Linearity was held within the range 0.3–20.0 ng/μL, with coefficients of determination (r2) better than 0.997. The within‐ and between‐day assay RSD at 2, 4, 8 ng/μL ranged from 0.03 to 4.7% and 0.5 to 7.0%, respectively in standards, from 1.3 to 7.9% and 3.3 to 7.3%, respectively in plasma, from 2.1 to 6.0% and 2.1 to 7.8%, respectively in urine and at 0.5, 1.0, 2.0 ng/μL ranged from 2.22 to 5.8% and 2.2 to 8.1%, respectively, in saliva. The mean relative recoveries were 96.3–108.6, 96.0–108.2, 94.3–107.1, 97.0–107.0% in within‐day assay and 96.8–107.7, 94.6–107.6, 93.2–105.8, 96.0–108.6 in between‐day assay for standard, plasma, urine, and saliva, respectively. The LOD and LOQ were 0.02–0.47 and 0.07–1.57 ng/μL, respectively. 相似文献
107.
Dr. Ain Uddin Seth R. Allen Adrian K. Rylski Connor J. O'Dea Dr. Jack T. Ly Dr. Tod A. Grusenmeyer Dr. Sean T. Roberts Dr. Zachariah A. Page 《Angewandte Chemie (International ed. in English)》2023,62(22):e202219140
The use of visible light to drive polymerizations with spatiotemporal control offers a mild alternative to contemporary UV-light-based production of soft materials. In this spectral region, photoredox catalysis represents the most efficient polymerization method, yet it relies on the use of heavy-atoms, such as precious metals or toxic halogens. Herein, spin-orbit charge transfer intersystem crossing from boron dipyrromethene (BODIPY) dyads bearing twisted aromatic groups is shown to enable efficient visible light polymerizations in the absence of heavy-atoms. A ≈5–15× increase in polymerization rate and improved photostability was achieved for twisted BODIPYs relative to controls. Furthermore, monomer polarity had a distinct effect on polymerization rate, which was attributed to charge transfer stabilization based on ultrafast transient absorption and phosphorescence spectroscopies. Finally, rapid and high-resolution 3D printing with a green LED was demonstrated using the present photosystem. 相似文献
108.
109.
Ullah Hayat Ullah Hafeez Taha M. Khan F. Rahim F. Uddin I. Sarfraz M. Shah S. A. Ali Aziz A. Mubeen S. 《Russian Journal of Organic Chemistry》2021,57(6):968-975
Russian Journal of Organic Chemistry - New benzimidazole derivatives were synthesized by reacting substituted phenacyl bromides with 1H-benzimidazole-2-thiols. The synthesized compounds were... 相似文献
110.
Mansour H. Almatarneh Abd Al‐Aziz A. Abu‐Saleh Kabir M. Uddin Raymond A. Poirier Peter L. Warburton 《International journal of quantum chemistry》2017,117(3):180-189
A detailed computational study of the deamination reaction of melamine by OH–, n H2O/OH–, n H2O (where n = 1, 2, 3), and protonated melamine with H2O, has been carried out using density functional theory and ab initio calculations. All structures were optimized at M06/6‐31G(d) level of theory, as well as with the B3LYP functional with each of the basis sets: 6‐31G(d), 6‐31 + G(d), 6‐31G(2df,p), and 6‐311++G(3df,3pd). B3LYP, M06, and ω B97XD calculations with 6‐31 + G(d,p) have also been performed. All structures were optimized at B3LYP/6‐31 + G(d,p) level of theory for deamination simulations in an aqueous medium, using both the polarizable continuum solvation model and the solvation model based on solute electron density. Composite method calculations have been conducted at G4MP2 and CBS‐QB3. Fifteen different mechanistic pathways were explored. Most pathways consisted of two key steps: formation of a tetrahedral intermediate and in the final step, an intermediate that dissociates to products via a 1,3‐proton shift. The lowest overall activation energy, 111 kJ mol?1 at G4MP2, was obtained for the deamination of melamine with 3H2O/OH?. 相似文献