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111.
Li C Alam MM Bolisetty S Adamcik J Mezzenga R 《Chemical communications (Cambridge, England)》2011,47(10):2913-2915
New biocompatible temperature-responsive hydrogels have been obtained by using unprecedented low concentration of amyloid fibril-PNiPAM hybrids. The viscoelasticity of the hydrogels can be finely controlled by tuning the PNiPAM layers without changing the structure or concentration of the amyloid fibrils. 相似文献
112.
Chinnaswamy Thangavel Vijayakumar Rajendran Surender Kumaraswamy Rajakumar Sarfaraz Alam 《Journal of Thermal Analysis and Calorimetry》2011,103(2):693-699
The compound 2,2-bis[4-(4-maleimidophenoxy phenyl)]propane was prepared by the imidization of bisamic acid of 2,2-bis(4-aminophenoxy
phenyl)propane. Various nanoclays were blended with this bismaleimide and thermally cured. The structural characterization
of the synthesized materials and the thermal properties of the bismaleimide and their blends were investigated through FTIR,
1H and 13C NMR, differential scanning calorimetry and thermo gravimetric analysis. Among the various clays investigated, Cloisite 15A
shows strong influence on the cure exotherm of bismaleimide. Introduction of clay mineral into bismaleimide shifts the onset
of curing exotherm to higher temperature and is nearly 40 °C. The thermal stability of the clay loaded cured bismaleimide
increases and the presence of clay particles in the cured bismaleimide matrix enhances the char formation. 相似文献
113.
Antioxidant and antityrosinase activities of various extracts from the fruiting bodies of Lentinus lepideus 总被引:1,自引:0,他引:1
Yoon KN Alam N Lee KR Shin PG Cheong JC Yoo YB Lee TS 《Molecules (Basel, Switzerland)》2011,16(3):2334-2347
Lentinus lepideus is an edible mushroom currently available in Korea. The acetone, methanol and hot water extracts were prepared and assayed for their antioxidant and antityrosinase inhibitory activities. The hot water extract showed the strongest β-carotene-linoleic acid inhibition compared to the other extracts. At 8 mg/mL, the methanolic extract showed a high reducing power of 1.21. The acetone and methanol extracts were more effective in scavenging DPPH radicals than the hot water extract. The strongest chelating effect was obtained from the methanolic extract. Xanthine oxidase and tyrosinase inhibitory activities of the acetonic, methanol and hot water extracts increased with increasing concentration. Gallic acid, chlorogenic acid, vanillin, naringin, naringenin, formononetin, and biochanin-A were detected in the acetonitrile and hydrochloric acid (5:1) solvent extract. This study suggests that fruiting bodies of L. lepideus can potentially be used as a readily accessible source of natural antioxidants. 相似文献
114.
In the present work, we have critically examined the origin of strong two-photon transition probability of a donor-acceptor substituted bisanthene molecule that imitates a small piece of edge passivated (4, 4) graphene nanoribbon. In our calculations, we have considered -OMe, and -NH(2) as donors and -NO(2) as an acceptor. The one- and two-photon absorption parameters are evaluated using state-of-the-art linear and quadratic response theory, respectively, and all these calculations are carried out within the framework of time dependent density functional theory. To give a proper judgment on our findings, we have used the long-range corrected CAMB3LYP functional for all of the time dependent calculations. The present investigation reveals that the bisanthene molecule with three pairs of donor/acceptor moiety has a lower two-photon transition probability than that of a suitably designed bisanthene with only a single pair of donor/acceptor moiety. This in silico observation is consistent for all of the donor/acceptor moieties chosen in the present work. A comprehensive analysis at the two state model level of theory clearly offers us a verdict that by placing the donor/acceptor moiety in a suitable position of bisanthene, we can create a significant asymmetry in the electron density in the first excited state, which eventually leads to a significant difference in the ground and excited state dipole moment and is attributed to the higher two-photon transition probability of a particular bisanthene with a single pair of donor/acceptor moiety than bisanthene with three pairs of donor/acceptor. 相似文献
115.
Srikar Middala Sean Campbell Catalina Olea Austen Scruggs Alam S. Hasson 《国际化学动力学杂志》2011,43(9):507-521
The kinetics and mechanism of gas‐phase propylene oxide (PPO) reactions were studied in a 142‐L reaction chamber by long‐path Fourier transform infrared spectroscopy at atmospheric pressure and 298 K. Rate coefficients for the reaction of PPO with ozone (O3), chlorine atoms (Cl), and hydroxyl radicals (OH) were measured using the relative rate technique. Product yields of acetic acid, acetic formic anhydride, formic acid, and carbon monoxide were determined for the following reactions: PPO with Cl both in the presence and absence of NO, PPO with OH and NO, methyl acetate with Cl both in the presence and absence of NO, and ethyl formate with Cl both in the presence and absence of NO. The measured rate coefficients for PPO with O3, Cl, and OH are <3.5 × 10?21 cm3 molecule?1 s?1, (3.0 ± 0.7) × 10?11 cm3 molecule?1 s?1, and (3.0 ± 1.0) × 10?13 cm3 molecule?1 s?1, respectively. The carbon balance for the products measured ranged from 10% (for OH + PPO) to 100% (for Cl + methyl acetate in the absence of NO). The mechanistic and atmospheric implications of these measurements are discussed. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 507–521, 2011 相似文献
116.
High performance radar transparent materials (RTMs) are important materials for the fabrication of radomes, nosecones, etc. of high velocity aerospace vehicles. RTMs with good mechanical performance and temperature capability are required for such applications. Toward this, fabric reinforced nano‐reinforced matrix composites (FRNCs), using reinforcing E‐glass fabric in Cloisite 30B reinforced polyetherimide (PEI) nanocomposite matrix (GNRPEI), was prepared. The properties of GNRPEI were evaluated and compared with E‐glass fabric reinforced PEI composites (GRPEI) with special reference to their radar transparent character for aerospace applications. Tensile and flexural properties along with interlaminar shear strength of GRPEI were observed to be lower than those of GNRPEI. Thermal behavior of both the composites was similar in differential scanning calorimetry and thermal gravimetric analysis. But, in dynamic mechanical analysis, an increase in storage modulus and decrease in loss tangent were observed in GNRPEI compared to GRPEI. The values of dielectric constant and loss tangent of GNRPEI were lesser than those of GRPEI, but no significant difference was observed in the values of transmission and reflection losses for both the composites at 8–12 GHz frequency. FRNCs, based on organoclay reinforced PEI matrix, hold good promise as high performance RTMs. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
117.
Sitaram Pal Sukumar Ghosh Bimal K. Banik Shaikh Khairul Alam Usha Ranjan Ghatak 《合成通讯》2013,43(14):2203-2216
The bridged-ethers, (±)-2-methoxy-9a-carbamorphinan (1b) and (±)-2-methoxy-9a-carba-14α-morphinan(2b) have been synthesized. The acid-catalyzed cyclizations of 1-m-methoxy benzyloctalone 3b and 1-m-methoxybenzyloctalins 4b proceed with high regio-and stereoselectivities leading mostly to the bridged-ketone 14 and ether 1b respectively, along with o-methoxy-tetracyclic ketone 15 and the ether 17, in addition to other minor products. 相似文献
118.
The growth ofBacillus amyloliquefaciens in the aqueous two-phase system, made up of polyethylene glycol, dextran, and water, was investigated. Generally,Bacillus partitions in the dextran phase, but the magnitude of the separation depends largely on the overall composition of polymers
in the phase system. The kinetics of growth ofBacillus amyloliquefaciens was studied in the polyethylene glycol-rich continuous phase, dextran-rich dispersed phase, and in the mixed phase. From
the kinetic data it appears that increasing the overall polymer composition causes the cells to adsorp at the interface. On
the other hand, partition measurements indicate that increasing polymer concentrations make the cell partitioning more one-sided.
This anomaly is explained by studying the interfacial adsorption of cells via dynamic surface tension measurements. 相似文献
119.
We have studied the clouding phenomena in promethazine hydrochloride (PMT) aqueous solutions in presence of electrolytes and non-electrolytes. PMT, a tranquillizer, shows phase separation. The cloud point (CP) decreases with increase in pH due to deprotonation of drug molecules. At constant pH, increasing salt addition causes an increase in CP, which is explained on the basis of their position in Hofmeister series and their hydrated radii. With quaternary salts CP increases due to adsorption/mixed micelle formation. Ureas decrease the CP and the behavior is explained on the basis of removal of water from the headgroup region. 相似文献
120.
Reactions of 2‐bromo‐6‐(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)pyridine ( L1 ) and 2,6‐bis(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)pyridine ( L2 ) with NiCl2 and NiBr2 led to the formation of their respective metal complexes [NiCl2(L1)] ( 1 ), [NiBr2(L1)] ( 2 ) and [NiBr2(L2)] ( 3 ) in moderate to high yields. The complexes were characterized using elemental analyses, mass spectrometry and single‐crystal X‐ray diffraction for 2 . The solid‐state structure of 2 confirmed the bidentate coordination mode of L1 and formation of a monometallic compound. Activation of the nickel(II) pre‐catalysts with methylaluminoxane afforded active catalysts in the ethylene oligomerization reaction to produce mainly butenes (84–86%). In contrast, activation of nickel(II) pre‐catalyst 2 with ethylaluminium dichloride resulted in partial Friedel–Crafts alkylation of the toluene solvent by the preformed oligomers. Complex structure, nature of co‐catalyst employed, type of solvent and reaction conditions influenced the catalytic behaviour of these pre‐catalysts. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献