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31.
Bimlesh Lochab Indra K. Varma Jayashree Bijwe 《Journal of Thermal Analysis and Calorimetry》2013,111(2):1357-1364
This article describes synthesis, characterization and properties of blends of benzoxazine (Bz) monomers, i.e., m-alkylphenyl-3,4-dihydro-2H-benzoxazine (Bz-C), 6,6′-(propane-2,2-diyl)bis(3-phenyl-3,4-dihydro-2H-benzoxazine (Bz-A) and 3-phenyl-3,4-dihydro-2H-benzoxazine-p-carboxylic acid (Bz-pA). Binary blends of Bz-C with Bz-pA, and Bz-A with Bz-pA were prepared by first synthesizing Bz-C or Bz-A followed by the addition of all the ingredients of Bz-pA. In a similar manner, ternary blends of Bz-C, Bz-A and Bz-pA were prepared by first synthesizing Bz-C and subsequent addition of all the ingredients of Bz-A and Bz-pA in one pot. The Bz monomer blends were characterized by 1H-NMR, FTIR spectroscopy, and differential scanning calorimetry. The temperature of onset of curing (T o), due to ring-opening polymerization of Bz was found to decrease significantly by incorporation of carboxyl groups (Bz-pA) showing thereby the catalytic effect of acid functionality. Bz polymers showed good thermal stability and incorporation of Bz-pA in blends resulted in a highly cross-linked network. The interlaminar shear strength of glass fabric reinforced composites and the lap shear strength of metal–metal joints using these resin blends was also investigated. 相似文献
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33.
Layer BD York A Antonsen TM Varma S Chen YH Leng Y Milchberg HM 《Physical review letters》2007,99(3):035001
We report the development of corrugated "slow-wave" plasma guiding structures with application to quasiphase-matched direct laser acceleration of charged particles and generation of a wide spectrum of electromagnetic radiation. These structures support guided propagation at intensities up to 2 x 10(17) W/cm(2), limited by our current laser energy and side leakage. Hydrogen and argon plasma waveguides up to 1.5 cm in length with corrugation period as short as 35 microm are generated in a cryogenic cluster jet. Experimental data are consistent with simulations showing periodic modulations of the laser pulse intensity. 相似文献
34.
Jiabin Zhang Ding Liu Varma Saikam Madhusudhan R. Gadi Christopher Gibbons Xuan Fu Heliang Song Jin Yu Shukkoor M. Kondengaden Prof. Dr. Peng G. Wang Prof. Dr. Liuqing Wen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(45):19997-20001
Historically, researchers have put considerable effort into developing automation systems to prepare natural biopolymers such as peptides and oligonucleotides. The availability of such mature systems has significantly advanced the development of natural science. Over the past twenty years, breakthroughs in automated synthesis of oligosaccharides have also been achieved. A machine-driven platform for glycopeptide synthesis by a reconstructed peptide synthesizer is described. The designed platform is based on the use of an amine-functionalized silica resin to facilitate the chemical synthesis of peptides in organic solvent as well as the enzymatic synthesis of glycan epitopes in the aqueous phase in a single reaction vessel. Both syntheses were performed by a peptide synthesizer in a semiautomated manner. 相似文献
35.
36.
A. K. Varma 《Acta Mathematica Hungarica》1978,31(3-4):193-203
37.
C. Karthik Mario Maglione R. Vondermuhll K.B.R. Varma 《Solid State Communications》2006,139(6):268-272
Potassium lanthanum bismuth tantalate (K0.5La0.5Bi2Ta2O9), a new relaxor ferroelectric was synthesized via the solid-state reaction route. X-ray structural studies along with Rietveld refinement confirmed it to be an n=2 member of the Aurivillius family of oxides and the refined lattice parameters are , and . The appearance of 1/2{h00} and 1/2{hk0} type superlattice reflections in the electron diffraction patterns reflected the presence of ordered polar regions. A broad dielectric peak associated with frequency dependent dielectric maximum temperature was observed. The value of the diffuseness parameter γ=1.93, obtained from the fit of a modified Curie-Weiss law established the relaxor nature of the title compound. The dielectric relaxation obeyed the Vogel-Fulcher relation wherein and . The relaxor behavior was attributed to the local polar ordering on A-sites. 相似文献
38.
α,β-Unsaturated nitroalkenes are reduced to alkylamines in good yields by excess of borane-THF in presence of catalytic amount of sodium borohydride. 相似文献
39.
The Integrating Sphere Integrating Nephelometer is a novel and unique reciprocal nephelometer that uses an integrating sphere with attached truncation-reduction tubes to contain the sample volume and to integrate the scattered light. Its main advantage compared with current integrating nephelometers is a sevenfold reduction in truncation angle, which reduces errors in measured scattering from large particles. Additional features include improved sampling efficiency for large particles and a well-defined operating wavelength. 相似文献
40.
Jeselnik M Varma RS Polanc S Kocevar M 《Chemical communications (Cambridge, England)》2001,(18):1716-1717
The reaction of neat 5- or 8-oxobenzopyran-2(1H)-ones, 1-3, with a variety of aromatic and heteroaromatic hydrazines, 4, is remarkably accelerated upon irradiation in a household microwave oven in the absence of any catalyst, solid support or solvent thus providing an environmentally friendly route to several heterocyclic hydrazones. 相似文献