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131.
Ajaz Hussain Shagufta Perveen Abdul Malik Amna Nisar Khan Rasool Bakhsh Tareen 《Helvetica chimica acta》2010,93(6):1101-1104
Marrusidins A ( 1 ) and B ( 2 ), two new labdane‐type diterpenes, were isolated from the CHCl3‐soluble subfraction of Marrubium anisodon, along with polyodonine. Their structures were assigned with the aid of 1H‐ and 13C‐NMR spectra and by COSY, HMQC, NOESY, and HMBC experiments. 相似文献
132.
Electron beam melting is being used to modify the microstructure of the surfaces of materials due to its ability to cause localized melting and supercooling of the melt. This article presents an experimental study on the surface modification of Ni-based superalloy (Inconel 625) reinforced with SiC ceramic particles under electron beam melting. Scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction techniques have been applied to characterize the resulted microstructure. The results revealed growth of novel structures like wire, rod, tubular, pyramid, bamboo and tweezers type morphologies in the modified surface. In addition to that fibrous like structure was also observed. Formation of thin carbon sheet has been found at the regions of decomposed SiC. Electron beam modified surface of Inconel 625 alloy has been hardened twice as compared to the as-received samples. Surface hardening effect may be attributed to both the formation of the novel structures as well as the introduction of Si and C atom in the lattice of Inconel 625 alloy. 相似文献
133.
Shahid Mahmud Muhammad Saleem Saima Siddique Rauf Ahmed Razia Khanum Zahida Perveen 《Journal of Saudi Chemical Society》2009,13(2):195-198
Essential oil of Citrus acida Roxb. var. sour lime was analyzed by GC–MS. Out of 59 components 18 were identified from their fragmentation pattern. Among the identified constituents, o-cymene (16.62%) was found as a major component followed by α-cedrene (10.57%), decadienal (8.043%), bisabolene (5.066%) and β-humelene (4.135%). Citronellyl acetate (2.371%), linalool acetate (2.371%), carvone (1.806%), decanone (1.474%), isopulegol acetate (1.296%), farnesol (1.254%), 4′-methoxyacetophenone (1.207%), and Δ-carene (1.070%) were found in minor quantities whereas α-terpineole (0.607%), dihydroxylinalool acetate (0.650%), cis-nerone (0.574%), caryophyllene oxide (0.433%), and 2,2-dimethyl-3,4-octadienal (0.375%) were found in minute amounts.The antimicrobial activity of the essential oil of C. acida was determined by disc diffusion method, against different bacteria (Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, Escherichia coli, Enterobacter aerogenes, Salmonella typhymurium) and fungi (Aspergillus ficuum, Aspergillus niger, Aspergillus fumigatus, Aspergillus flavis, Fusarium saloni, Fusarium oxysporum, Pencillium digitatum, Candida utilis). Maximum zone of inhibition was resulted against B. subtilis (22 mm) followed by C. utilis (20 mm) and B. cereus (19.8 mm), whereas the minimum zone of inhibition was shown by P. digitatum (10 mm). The inhibition zones, measured after 48 h and 96 h, showed that it is active against all tested bacteria and fungi. The results of antioxidant activity of essential oil of C. acida var. sour lime showed that it was able to reduce the stable radical DPPH to yellow-colored DPPH-H reaching 91.7% of DPPH scavenging effect comparative to ascorbic acid being a strong antioxidant reagent. 相似文献
134.
T. Jabbar K. Khan M. S. Subhani P. Akhter 《Journal of Radioanalytical and Nuclear Chemistry》2009,279(2):377-384
Assessment of 90Sr is of great interest owing to the fact that this artificially produced radionuclide has high radiological importance because
of its high fission yield, chemical similarity to calcium and its relatively long biological and physical half-life. To assess
the likely hazard to population, low level 90Sr in environmental samples is determined using pre-equilibrated tri-butyl phosphate (TBP) solvent and extraction-liquid scintillation
procedure. 90Y is selectively extracted from nitric acid solution into TBP solvent and stripped into aqueous phase as oxalate. The activity
is finally measured by low level liquid scintillation counter using Cerenkov radiation. The specific activity is found only
in three vegetation samples with average value of 2.86±1.7 Bq·kg−1 of dry weight. In all other samples analyzed, the activity is below the detectable limit, i.e., 0.03 Bq. Results obtained
are comparable with other areas of Pakistan. The chemical recovery of 90Y varies from 75 to 90% for soil, vegetation and water. The present study provides a general background of the detectable
radionuclide for the surveyed area that will be helpful in any radiological emergency. 相似文献
135.
Haugaard-Kedström LM Shabanpoor F Hossain MA Clark RJ Ryan PJ Craik DJ Gundlach AL Wade JD Bathgate RA Rosengren KJ 《Journal of the American Chemical Society》2011,133(13):4965-4974
Relaxin-3 is a two-chain disulfide-rich peptide that is the ancestral member of the relaxin peptide family and, together with its G protein-coupled receptor RXFP3, is highly expressed in the brain. Strong evolutionary conservation of relaxin-3 suggests a critical biological function and recent studies have demonstrated modulation of sensory, neuroendocrine, metabolic, and cognitive systems. However, detailed studies of central relaxin-3-RXFP3 signaling have until now been severely hampered by the lack of a readily available high-affinity antagonist for RXFP3. Previous studies have utilized a complex two-chain chimeric relaxin peptide, R3(BΔ23-27)R/I5, in which a truncated relaxin-3 B-chain carrying an additional C-terminal Arg residue was combined with the insulin-like peptide 5 (INSL5) A-chain. In this study we demonstrate that, by replacing the native Cys in this truncated relaxin-3 B-chain with Ser, a single-chain linear peptide of 23 amino acids that retains high-affinity antagonism for RXFP3 can be achieved. In vivo studies demonstrate that this peptide, R3 B1-22R, antagonized relaxin-3/RXFP3 induced increases in feeding in rats after intracerebroventricular injection. Thus, R3 B1-22R represents an excellent tool for biological studies probing relaxin pharmacology and a lead molecule for the development of synthetically tractable, single-chain RXFP3 modulators for clinical use. 相似文献
136.
Al-Taweel AM Perveen S El-Shafae AM Fawzy GA Malik A Afza N Iqbal L Latif M 《Molecules (Basel, Switzerland)》2012,17(3):2675-2682
Nine compounds have been isolated for the first time from Celtis africana, namely trans-N-coumaroyltyramine (1), trans-N-feruloyltyramine (2), trans-N-caffeoyltyramine (3), lauric acid (4), oleic acid (5), palmitic acid (6), lupeol (7), β-sitosterol (8) and oleanolic acid (9), respectively. Their structures have been elucidated by different spectroscopic techniques. The isolated compounds were screened for their antioxidant, anti-inflammatory and acetylcholinestrease enzyme inhibitory activities. Compounds 1-3 showed significant antioxidant and anti-inflammatory activities and weak to moderate acetylcholinestrease enzyme inhibition activity. 相似文献
137.
Colocynthins A–C ( 1 – 3 , resp.), new pentacyclic cucurbitane type triterpene glucosides, have been isolated from the AcOEt‐soluble fraction of the fruits of Citrullus colocynthis, along with three known compounds, β‐sitosterol 3‐O‐β‐D ‐glucopyranoside, elaterinide, and bryoamaride. Their structures were determined on the basis of 1H‐ and 13C‐NMR spectra, DEPT, and COSY, NOESY, HMQC, and HMBC experiments. 相似文献
138.
Khan KM Saify ZS Arif Lodhi M Butt N Perveen S Maharvi GM Choudhary MI Atta-Ur-Rahman 《Natural product research》2006,20(6):523-530
A variety of piperidines (2-12, 14-26) with variable substituents at N-atoms have been synthesized and evaluated as urease inhibitors. The synthesized compounds showed varying degree of urease inhibitory activity ranging from 31.97 to 254 microM. The size and electron-donating or -withdrawing effects of substituents influence the activity, which lead to the formation of urease inhibitors. 相似文献
139.
Fixed point theorems for multivalued non-linear $F$-contractions on quasi metric spaces with an application 下载免费PDF全文
Mohammad Imd Atiya Perveen Waleed M. Alfaqih 《Journal of Applied Analysis & Computation》2019,9(3):901-915
In this paper, we introduce $(\alpha,\beta)$-type $F-\tau$ contraction and utilize the same to prove some fixed point results for multivalued mappings in quasi metric spaces. Furthermore, we furnish with some examples to exhibit the utility of our results. As an application, we establish the existence of a solution for a non-linear integral equation. 相似文献
140.
Khalid Khan P. Akhter S. D. Orfi 《Journal of Radioanalytical and Nuclear Chemistry》2005,265(3):371-375
Summary Activity concentrations of naturally occurring radionuclides, i.e., 226Ra, 232Th and 40K, were measured in sand samples of north western areas of Pakistan using gamma-spectrometry. The measured ranges of activity concentrations for 226Ra, 232 Th and 40K were 36.9-51.9, 52.5-67.6 and 680-784 Bq . kg-1, respectively. Associated external dose was calculated using Monte Carlo simulation technique. A theoretical model to determine the gamma dose rate at 1 m height from the sand was employed for calculation the mass attenuation coefficient and self absorption in sand slab for the gamma-energies of these radionuclides and their progeny. The weighted average values of the measured gamma dose rates were 3.3, 4.5 and 12.4 nGyh-1 for 226Ra, 232 Th and 40K, respectively, with effective dose of 0.022±0.004 mSv . y-1. Monte Carlo simulation shows that the sand slabs having more than 15 cm effective thickness contribute very little to the external gamma dose rate. The values of the external dose rate and annual effective dose were found to be much lower than the world average as well as from other countries of the world. 相似文献