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81.
Some novel functionalized indeno[1,2-b]furans were synthesized from the reaction of indandione/indanone and aldehydes at room temperature followed by the reaction of the Knoevenagel condendensed intermediate with 4-hydroxycoumarins in the presence of iodine as catalyst in dimethyl sulfoxide (DMSO) under thermal conditions. The reaction involved in a condensation and Michael addition followed by lactone ring opening and intramolecular cyclization process to afford the product in high yield in easy work-up procedure. 相似文献
82.
A hybrid catalyst has been prepared by incorporating sulfonic acid onto cobalt ferrite magnetic nanoparticles. The catalyst was successfully applied for rapid (20?min) synthesis of α,α-dibromoketones directly from alkynes and NBS. The reaction works well in the presence of 10?wt% of the catalyst at room temperature to produce the desired products in high yield. The catalyst could be recovered using an external magnet and reused without appreciable change in activity. 相似文献
83.
Sounak Dutta Dibyendu Das Antara Dasgupta Prasanta Kumar Das Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(5):1493-1505
The gelation of ionic liquids is attracting significant attention because of its large spectrum of applications across different disciplines. These ‘green solvents’ have been the solution to a number of common problems due to their eco‐friendly features. To expand their applications, the gelation of ionic liquids has been achieved by using amino acid‐based low‐molecular‐weight compounds. Variation of individual segments in the molecular skeleton of the gelators, which comprise the amino acid and the protecting groups at the N and C termini, led to an understanding of the structure–property correlation of the ionogelation process. An aromatic ring containing amino acid‐based molecules protected with a phenyl or cyclohexyl group at the N terminus were efficient in the gelation of ionic liquids. In the case of aliphatic amino acids, gelation was more prominent with a phenyl group as the N‐terminal protecting agent. The probable factors responsible for this supramolecular association of the gelators in ionic liquids have been studied with the help of field‐emission SEM, 1H NMR, FTIR, and luminescence studies. It is the hydrophilic–lipophilic balance that needs to be optimized for a molecule to induce gelation of the green solvents. Interestingly, to maximize the benefits from using these green solvents, these ionogels have been employed as templates for the synthesis of uniform‐sized TiO2 nanoparticles (25–30 nm). Furthermore, as a complement to their applications, ionogels serve as efficient adsorbents of both cationic and anionic dyes and were distinctly better relative to their organogel counterparts. 相似文献
84.
The study of protein conformational changes in the presence of surfactants and lipids is important in the context of protein
folding and misfolding. In the present study, we have investigated the mechanism of the protein conformational change coupled
with aggregation leading to size growth of Hen Egg White Lysozyme (HEWL) in the presence of an anionic detergent such as sodium
dodecyl sulphate (SDS) in alkaline pH. We have utilized intrinsic protein fluorescence (tryptophan) and extrinsic fluorescent
reporters such as 8-anilinonaphthalene-1-sulfonic acid (ANS), dansyl and fluorescein to follow the protein conformational
change in real-time. By analyzing the kinetics of fluorescence intensity and anisotropy of multiple fluorescent reporters,
we have been able to delineate the mechanism of surfactant-induced aggregation of lysozyme. The kinetic parameters reveal
that aggregation proceeds with an initial fast-phase (conformational change) followed by a slow-phase (self-assembly). Our
results indicate that SDS, below critical micelle concentration, induces conformational expansion that triggers the aggregation
process at a micromolar protein concentration range. 相似文献
85.
Qian X Allada K Dutta C Huang J Katich J Wang Y Zhang Y Aniol K Annand JR Averett T Benmokhtar F Bertozzi W Bradshaw PC Bosted P Camsonne A Canan M Cates GD Chen C Chen JP Chen W Chirapatpimol K Chudakov E Cisbani E Cornejo JC Cusanno F Dalton MM Deconinck W de Jager CW De Leo R Deng X Deur A Ding H Dolph PA Dutta D El Fassi L Frullani S Gao H Garibaldi F Gaskell D Gilad S Gilman R Glamazdin O Golge S Guo L Hamilton D Hansen O Higinbotham DW Holmstrom T Huang M Ibrahim HF Iodice M Jiang X Jin G 《Physical review letters》2011,107(7):072003
We report the first measurement of target single spin asymmetries in the semi-inclusive (3)He(e,e'π(±))X reaction on a transversely polarized target. The experiment, conducted at Jefferson Lab using a 5.9 GeV electron beam, covers a range of 0.16 < x < 0.35 with 1.4 < Q(2) < 2.7 GeV(2). The Collins and Sivers moments were extracted from the azimuthal angular dependence of the measured asymmetries. The π(±) Collins moments for (3)He are consistent with zero, except for the π(+) moment at x = 0.35, which deviates from zero by 2.3σ. While the π(-) Sivers moments are consistent with zero, the π(+) Sivers moments favor negative values. The neutron results were extracted using the nucleon effective polarization and measured cross section ratios of proton to (3)He, and are largely consistent with the predictions of phenomenological fits and quark model calculations. 相似文献
86.
It has long been known that thiol-terminated molecules self-assemble as commensurate monolayers on Au(111) surfaces. By spreading floating octadecanethiol monolayers on aqueous solutions of chloroauric acid (HAuCl4) and using x rays to reduce the gold ions as well as to probe the structure, we have observed the nucleation of (111)-oriented Au nanoparticles at thiol surfaces. This process may be similar to the formation of biogenic gold by bacteria. The thiol monolayer acts as a "soft template," changing its structure as Au crystals form so that there is a sqrt[3]×sqrt[3] commensurate relationship. 相似文献
87.
M. Anselmino H. Avakian D. Boer F. Bradamante M. Burkardt J. P. Chen E. Cisbani M. Contalbrigo D. Crabb D. Dutta L. Gamberg H. Gao D. Hasch J. Huang M. Huang Z. Kang C. Keppel G. Laskaris Z. -T. Liang M. X. Liu N. Makins R. D. Mckeown A. Metz Z. -E. Meziani B. Musch J. -C. Peng A. Prokudin X. Qian Y. Qiang J. W. Qiu P. Rossi P. Schweitzer J. Soffer V. Sulkosky Y. Wang B. Xiao Q. Ye Q. -J. Ye F. Yuan X. Zhan Y. Zhang W. Zheng J. Zhou 《The European Physical Journal A - Hadrons and Nuclei》2011,47(3):1-21
88.
S. K. Sharma K. Sudarshan P. Maheshwari D. Dutta P. K. Pujari C. P. Shah M. Kumar P. Bajaj 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,82(3-4):335-340
Poly vinyl alcohol (PVA) capped CdSe nanoparticles having size in the range of 7–17 nm have been synthesized through chemical route and characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Positron coincidence Doppler broadening (CDB) measurements have been carried out in these nanoparticles. It is observed that the electron momentum distributions show a variation in the core electron momentum region with the particle size. In order to examine the influence of defects, first principle calculations of electron momentum distributions in bulk CdSe and in the presence of Cd as well as Se vacancy defects have been performed. Comparison of experimental data with the calculated momentum distribution reveals the presence of Cd vacancy defects, the concentration of which decreases with the increase in the particle size. The present study also indicates possible Se enrichment on the surface of the nanoparticles with the decrease in the particle size. 相似文献
89.
Saurabh SahuRaj Kumar Dutta 《Journal of magnetism and magnetic materials》2011,323(7):980-987
A novel hybrid nanostructured material comprising superparamagnetic magnetite nanoparticles (MNPs) and pectin was synthesized by crosslinking with Ca2+ ions to form spherical calcium pectinate nanostructures, referred as MCPs, which were typically found to be 100-150 nm in size in dried condition, confirmed from transmission electron microscopy and scanning electron microscopy. The uniform size distribution was revealed from dynamic light scattering measurement. In aqueous medium the MCPs showed swelling behavior with an average size of 400 nm. A mechanism of formation of spherical MCPs is outlined constituting a MNP-pectin interface encapsulated by calcium pectinate at the periphery, by using an array of characterization techniques like zeta potential, thermogravimetry, Fourier transformed infrared and X-ray photoelectron spectroscopy. The MCPs were stable in simulated gastrointestinal fluid and ensured minimal loss of magnetic material. They exhibited superparamagnetic behavior, confirmed from zero field cooled and field cooled profiles and showed high saturation magnetization (Ms) of 46.21 emu/g at 2.5 T and 300 K. Ms decreased with increasing precursor pectin concentrations, attributed to quenching of magnetic moments by formation of a magnetic dead layer on the MNPs. 相似文献
90.
J. Glister G. Ron B.W. Lee R. Gilman A.J. Sarty S. Strauch D.W. Higinbotham E. Piasetzky K. Allada W. Armstrong J. Arrington H. Arenhövel A. Beck F. Benmokhtar B.L. Berman W. Boeglin E. Brash A. Camsonne J. Calarco J.P. Chen S. Choi E. Chudakov L. Coman B. Craver F. Cusanno J. Dumas C. Dutta R. Feuerbach A. Freyberger S. Frullani F. Garibaldi J.-O. Hansen T. Holmstrom C.E. Hyde H. Ibrahim Y. Ilieva C.W. de Jager X. Jiang M.K. Jones Hyekoo Kang A. Kelleher E. Khrosinkova E. Kuchina G. Kumbartzki J.J. LeRose R. Lindgren P. Markowitz S. May-Tal Beck E. McCullough D. Meekins 《Physics letters. [Part B]》2011