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351.
G. V. S. Shashidhar N. Satyanarayana E. V. Sundaram G. Sathaiah Lalitha Sirdeshmukh 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(8):1069-1080
Radiation-induced copolymerization of acrylonitrile with methyl acrylate was carried out in aqueous medium at room temperature. Different compositions of the copolymer were prepared and characterized by IR, 1H-NMR, thermal, and dielectric studies. NMR spectroscopy was used to determine the composition and stereochemistry of the copolymer. Glass transition temperature values (Tg ) were determined by DSC. Dielectric studies were carried out to understand the segmental motions and the effect of composition on dielectric loss. 相似文献
352.
Nikolaos Politakos Craig J. Weinman Marvin Y. Paik Harihara S. Sundaram Christopher K. Ober Apostolos Avgeropoulos 《Journal of polymer science. Part A, Polymer chemistry》2011,49(19):4292-4305
Six well defined PS‐b‐PB1,2 diblock copolymers (PS: polystyrene and PB: polybutadiene) with almost 100% of 1,2 microstructure for the PB segment were synthesized. Size exclusion chromatography (SEC), membrane osmometry (MO) and proton nuclear magnetic resonance spectroscopy (1H NMR) were used for verification of the molecular characteristics and the 100% ‐1,2 addition for the PB blocks. Modification with heptanoyl or pentadecafluorooctanoyl chloride was accomplished via hydroboration and subsequent oxidation, leading to hydroxylated PB blocks and was verified with 1H NMR and Fourier transform infrared (FTIR) spectroscopy. Only two samples were modified with both organic acid chloride derivatives. Structural characterization was accomplished via transmission electron microscopy (TEM) and small‐angle X‐ray scattering (SAXS) in all cases. The self‐assembly was more evident in the modified copolymers with the corresponding halides due to the increase of the molecular weight of the modified PB block. Taking into consideration the χN values in each case and comparing the results with those of PS‐b‐PI copolymers already reported in the literature the discrepancies with the theoretical predictions are very small or minimal. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
353.
P. Krishnan S. Sundaram N. Venkatasubramanian 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):23-29
Abstract The hydrolytic behaviour under alkaline conditions of a group of sulfur compounds containing an active methylene group, in aqueous solvent mixtures with dimethylsulfoxide as the co-solvent has been investigated. The substrates studied are substituted phenyl phenylmethanesulfonates (A), substituted phenyl p-nitrophenylmethanesulfonates (B) and substituted phenylsulfonylacetates (C). It is known that methylenes adjacent to the sulfonyl group are acidic and evidences are available for the formation of the corresponding anions in alkaline solutions. Structure-reactivity correlations strongly suggest that these react not by the conventional addition–elimination mechanism (BAC 2), but by an elimination-addition mechanism (ElcB) involving a slow decomposition of the corresponding anions. The rate of hydrolysis of (A) increases with increasing percentage of dimethylsulfoxide in the solvent mixtures, whereas, the reverse is the case with (B) and (C). The results are analysed on the basis of a spectrum of pathways in the ElcB mechanism, and on the basis of the relative solvation of ground and transition states of the reaction. 相似文献
354.
Asmaa Ahmed Mohamed Elsakka Nabil Elminshawy Ayman Mohamed Senthilarasu Sundaram 《Chemical record (New York, N.Y.)》2023,23(12):e202300229
In recent years, floating photovoltaic (FPV) technologies have gained more importance as a key source of clean energy, particularly in the context of providing sustainable energy to buildings. The rise of land scarcity and the need to reduce carbon emissions have made FPV systems a cost-effective solution for generating electricity. This review article aims to explore the rapidly growing trend of floating PV systems, which can be a practical solution for regions with limited land areas. The article discusses the structure of the PV modules used in FPV plants and key factors that affect site suitability choice. Moreover, the article presents various techniques for cooling and cleaning FPV to keep optimal performance and discusses feasible trends and prospects for the technology. Finally, this paper proposes the potential integration of FPV systems with other technologies to enhance energy generation efficiency and discusses other research aimed at the advancement of the technology. By examining the various features of FPV systems, this review article contributes to understanding the advantages and challenges associated with using this sustainable energy technology in different regional contexts. 相似文献
355.
Dr. Arpan Hazra Dr. Satyanarayana Bonakala Karteek K. Bejagam Prof. Dr. Sundaram Balasubramanian Prof. Dr. Tapas Kumar Maji 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(23):7792-7799
Simultaneous tuning of permanent porosity and modulation of magnetic properties by postsynthetic modification (PSM) with light in a metal–organic framework is unprecedented. With the aim of achieving such a photoresponsive porous magnetic material, a 3D photoresponsive biporous framework, MOF1, which has 2D channels occupied by the guest 1,2‐bis(4‐pyridyl)ethylene (bpee), H2O, and EtOH molecules, has been synthesized. The guest bpee in 1 is aligned parallel to pillared bpee with a distance of 3.9 Å between the ethylenic groups; this allows photoinduced PSM of the pore surface through a [2+2] cycloaddition reaction to yield MOF2. Such photoinduced PSM of the framework structure introduces enhanced CO2 selectivity over that of N2. The higher selectivity in MOF2 than that of MOF1 is studied through theoretical calculations. Moreover, MOF2 unveils reversible changes in Tc with response to dehydration–rehydration. This result demonstrates that photoinduced PSM is a powerful tool for fabricating novel functional materials. 相似文献
356.
Narendran Rajendran Shankar Subramaniam Lowrence Rene Christena Meenakshi Sundaram Muthuraman Nagarajan Sai Subramanian Brindha Pemiah 《Natural product research》2016,30(17):2002-2006
Scutellaria oblonga Benth., a hitherto phytochemically unexplored Indian medicinal folklore plant was extracted with acetone and subjected to chromatography to yield nine flavonoids, for the first time from this plant. Antimicrobial assays were performed against 11 foodborne pathogens, and three molecules (Techtochrysin, Negletein and Quercitin-3-glucoside) depicted significant activity. These molecules were assessed for their rate of antibacterial action using time–kill curves which depicted complete inhibition of most of the bacteria within 12–16 h. The significant biofilm-reducing capability exhibited by these three molecules formed a significant finding of the current study. In most of the experiments, a 90–95% reduction in biofilms was observed. Thus, flavonoids as natural molecules from S. oblonga could be further researched to be used as potent antimicrobial and antibiofilm agents. 相似文献
357.
358.
359.
R. Krishna D. Velmurugan S. Shanmuga Sundara Raj H.‐K. Fun M. S. Sundaram R. Raghunathan 《Crystal Research and Technology》2001,36(11):1289-1294
The title compound (6,6‐dimethyl‐cis‐6H,6aH,7H,12bH,13H‐bis[1]benzopyrano[4,3‐b:4',3'‐d]pyran‐13‐one) crystallizes in monoclinic space group P21 /c with Z = 4. The unit cell dimensions are a = 8.6231(2) Å, b =10.0260(2) Å, c = 19.8376(2) Å, and β = 102.1(1)°, V = 1674.51(5) Å3 , Dcal = 1.326 Mg/m3. The coumarin moiety is in the planar conformation, the dioxadecalin moiety is cis fused and within the dioxadecalin moiety both the rings are in half cahir/sofa conformations. The structure has many C‐H … O type interactions. 相似文献