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排序方式: 共有266条查询结果,搜索用时 15 毫秒
31.
N Murugesan Z Gu PD Stein S Bisaha S Spergel R Girotra VG Lee J Lloyd RN Misra J Schmidt A Mathur L Stratton YF Kelly E Bird T Waldron EC Liu R Zhang H Lee R Serafino B Abboa-Offei P Mathers M Giancarli AA Seymour ML Webb JT Hunt 《Canadian Metallurgical Quarterly》1998,41(26):5198-5218
Substitution at the ortho position of N-(3,4-dimethyl-5-isoxazolyl) benzenesulfonamide led to the identification of the biphenylsulfonamides as a novel series of endothelin-A (ETA) selective antagonists. Appropriate substitutions on the pendant phenyl ring led to improved binding as well as functional activity. A hydrophobic group such as isobutyl or isopropoxyl was found to be optimal at the 4'-position. Introduction of an amino group at the 2'-position also led to improved analogues. Combination of the optimal 4'-isobutyl substituent with the 2'-amino function afforded an analogue (20, BMS-187308) with improved ETA binding affinity and functional activity. Compound 20 also has good oral activity in inhibiting the pressor effect caused by an ET-1 infusion in rats. Doses of 10 and 30 micromol/kg iv 20 attenuated the pressor responses due to the administration of exogenous ET-1 to conscious monkeys, indicating that the compound inhibits the in vivo activity of endothelin-1 in nonhuman primates. 相似文献
32.
Vinu A Shanmugapriya K Chandrasekar G Murugesan V Ariga K 《Journal of nanoscience and nanotechnology》2005,5(4):542-549
As nanoporous reactor, mesoporous silicates containing aluminum acidic site with n(Si)/n(Al) ratio up to 7 (AISBA-15) were prepared through a simple one-pot synthesis, which was recently developed by parts of us. The obtained materials were satisfactorily characterized by XRD and nitrogen adsorption/desorption and have regularly arranged hexagonal structures with pore diameters in the 9.6-11.8-nm range. The density and strength of the acid sites were determined using temperature-programmed desorption (TPD) of pyridine and controlled distribution between weak, moderate, and strong acid sites was demonstrated. The alkylation of ethylbenzene in a fixed-bed flow-type reactor using the AISBA-15 nanoporous reactor was carried out under various conditions such as temperature, feed ratio, flow rate, and time on stream. Interestingly, perfect regioselectivity between the m-isomer and the o-/p-isomers of diethylbenzene was achieved, where 100% selectivity of the m-isomer or the o-/p-isomers can be obtained by simply tuning the reaction temperature by using AISBA-15 catalyst with appropriate aluminum content. 相似文献
33.
Govindasamy Kottur Selvaraj Venkatesan Ramasamy Shanmugasundaram Senthil Kumar Subramanian Murugesan 《Journal of the science of food and agriculture》2010,90(9):1533-1537
BACKGROUND: Quality of tea depends on the cultivar and climatic conditions. Biochemical pathways within the plant and climatic factors can result in noticeable changes in chemical composition, which determine the quality of tea. Black tea quality attributes are influenced by various forms of catechins, namely gallated, non‐gallated, dihydroxylated and trihydroxylated catechins and their ratios. Hence the variations in grouped catechins and their synthesizing enzyme in relation to quality of south Indian black tea grown in different seasons and different cultivars were studied. RESULTS: Gallated, non‐gallated, dihydroxylated, trihydroxylated catechins and catechin index were significantly higher in crop shoots harvested during summer. A significant and wide diversity in various forms of catechins was noticed among the cultivars tested. Among the cultivars, UPASI‐3 registered the higher amount of various forms of catechins and activity of phenylalanine ammonia lyase (PAL), followed by UPASI‐9 and UPASI‐17 respectively, while the lowest amount was exhibited by ‘Assam’ seedlings and TRI‐2043. CONCLUSION: Overall quality as evaluated by tea tasters was positively correlated to the cultivars and seasons tested. This positive correlation can be attributed to higher levels of grouped catechins and PAL activity. Thus the contents of various forms of catechins could be the most important quality parameter of the south Indian black teas. Copyright © 2010 Society of Chemical Industry 相似文献
34.
S. Sudha S. Vishnu Priya J. Herbert Mabel M. Palanichamy V. Murugesan 《Journal of Porous Materials》2009,16(2):215-226
Al-MCM-41, Fe,Al-MCM-41 and Zn,Al-MCM-41 materials with different silicon to metal ratios were synthesized hydrothermally
and characterized by XRD, BET, FT-IR, Acidity measurement by pyridine adsorbed FT-IR spectroscopy, 29Si and 27Al MAS NMR and ESR techniques. The orderly arrangement of mesoporous materials was clearly revealed from the XRD patterns.
29Si and 27Al MAS NMR established the co-ordination environment of silicon and aluminium. Electron paramagnetic resonance (EPR) study
confirmed the co-ordination environment of Fe in Fe,Al-MCM-41 framework. The catalytic activity of these materials was evaluated
in the vapour phase alkylation and acylation of ethylbenzene with ethyl acetate in the temperature range between 250 and 400 °C.
The products were found to be 1,3-diethylbenzene (1,3-DEB), 1,4-diethylbenzene (1,4-DEB), 1,2-diethylbenzene (1,2-DEB), 4-ethylacetophenone
(4-EAP) and acetophenone (AP). The reaction products revealed that activation of ethyl acetate is a convenient route for both
alkylation and acylation reactions. The order of the catalysts activity for the reaction is found to be Fe,Al-MCM-41 (50) > Fe,Al-MCM-41
(100) > Zn,Al-MCM-41 (50) > Zn,Al-MCM-41 (100) > Al-MCM-41 (50) > Al-MCM-41 (100). In addition to the density of acid sites,
the strength of acid sites is also important for this reaction. The effects of temperature, feed ratio, WHSV and time on stream
were also examined and the results are discussed. 相似文献
35.
S. Vishnu Priya J. Herbert Mabel S. Gopalakrishnan M. Palanichamy V. Murugesan 《Journal of Porous Materials》2009,16(4):419-427
MAPO-36 was synthesized hydrothermally by isomorphic substitution of Mg2+ in the framework of AlPO-36 and ion-exchanged with Fe3+, Zn2+, La3+ and Ce3+ by wet method. The materials were characterized by XRD, TGA, TPD (ammonia) and SEM-EDX. XRD revealed absence of structural
degradation after ion-exchange. TPD (ammonia) showed selective ion-exchange of strong acid sites in ion-exchanged MAPO-36.
The weight loss around 550 °C in TGA for Fe, La and CeMAPO-36 suggested conversion of M(OH)2+ to MO+. Toluene disproportionation was carried over all catalysts in which diphenyl methane derivative was suggested to be the principle
intermediate in the formation of p-xylene and other products. The time on stream study showed exclusive formation of p-xylene after 6 h. 相似文献
36.
37.
Nanoclays still hold a great strength in biomedical nanotechnology applications due to their exceptional properties despite the development of several new nanostructured materials. This article reviews the recent advances in copolymer/clay nanocomposites with a focus on health care applications. In general, the structure of clay comprises aluminosilicate layers separated by a few nanometers. Recently, nanoclay‐incorporated copolymers have attracted the interest of both researchers and industry due to their phenomenal properties such as barrier function, stiffness, thermal/flame resistance, superhydrophobicity, biocompatibility, stimuli responsiveness, sustained drug release, resistance to hydrolysis, outstanding dynamic mechanical properties including resilience and low temperature flexibility, excellent hydrolytic stability, and antimicrobial properties. Surface modification of nanoclays provides additional properties due to improved adhesion between the polymer matrix and the nanoclay, high surface free energy, a high degree of intercalation, or exfoliated morphology. The architecture of the copolymer/clay nanocomposites has great impact on biomedical applications, too, by providing various cues especially in drug delivery systems and regenerative medicine. 相似文献
38.
Thomas Paul V. Mahadevan S. Kumar Krovvidi S. C. S. P. Goyal Sunil Murugesan S. Thirumurugesan R. Ezhilarasi T. Parameswaran P. Raju S. Saroja S. 《Journal of Failure Analysis and Prevention》2019,19(1):237-244
Journal of Failure Analysis and Prevention - A motorized bellow-sealed valve in the steam generator leak detection circuit of fast breeder test reactor developed sodium leak while carrying out... 相似文献
39.
Fatih Kalkan Sai Kranthi Vanga Ramesh Murugesan Valerie Orsat Vijaya Raghavan 《Drying Technology》2017,35(5):527-533
This study was performed to investigate the influence of air inlet temperature (AIT) on the microencapsulation of hazelnut oil by spray drying. Encapsulated powders were analyzed for moisture content, powder yield, surface oil, encapsulation efficiency (EE), bulk density, and particle morphology. The obtained results demonstrated that moisture content, surface oil, and bulk density decreased by 37.8, 27.5, and 33%, respectively as AIT increased from 140 to 220°C. However, powder yield and encapsulation efficiency increased considerably with the rise in AIT. Higher EEs of about 75–80% were observed in this study. 相似文献
40.