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61.
O. P. S. Negi H. Dehnen Gaurav Karnatak P. S. Bisht 《International Journal of Theoretical Physics》2011,50(6):1908-1918
Postulating the existence of magnetic monopole in electromagnetism and Heavisidian monopoles in gravitational interactions,
a unified theory of gravi-electromagnetism has been developed on generalizing the Schwinger-Zwanziger formulation of dyon
to quaternion in simple and consistent manner. Starting with the four Lorentz like forces on different charges, we have generalized
the Schwinger-Zwanziger quantization parameters in order to obtain the angular momentum for unified fields of dyons and gravito-dyons
(i.e. Gravi-electromagnetism). Taking the unified charge as quaternion, we have reformulated manifestly covariant and consistent
theory for the dynamics of four charges namely electric, magnetic, gravitational and Heavisidian associated with gravi electromagnetism. 相似文献
62.
Kuntrapakam Hema Rajesh G. Gonnade Kana M. Sureshan 《Angewandte Chemie (International ed. in English)》2020,59(7):2897-2903
The synthesis of crystalline helical polymers of trehalose via topochemical azide–alkyne cycloaddition (TAAC) of a trehalose‐based monomer is presented. An unsymmetrical trehalose derivative having azide and alkyne crystallizes in two different forms having almost similar packing. Upon heating, both the crystals undergo TAAC reaction to form crystalline polymers. Powder X‐ray diffraction (PXRD) studies revealed that the monomers in both the crystals polymerize in a crystal‐to‐crystal fashion; circular dichroism (CD) studies of the product crystals revealed that the formed polymer is helically ordered. This solvent‐free, catalyst‐free polymerization method that eliminates the tedious purification of the polymeric product exemplifies the advantage of topochemical polymerization reaction over traditional solution‐phase polymerization. 相似文献
63.
Organic reactions catalysed by commercially available lipases, reported in recent years from our own laboratory and those
published by others are described, confining the discussions to esteriflcation and hydrolytic reactions only. The text gives
an insight into the variety of substrates accepted by these lipases and their potential applications to catalyse reactions
regio-, chemo-, enantio- and diastereoselectively to produce compounds of industrial, commercial, pharmaceutical and synthetic
interest. 相似文献
64.
Hema Ramachandran 《Pramana》2002,58(2):313-323
Experimental realization of mirrorless lasers in the last decade have resulted in hectic activity in this field, due to their
novelty, simplicity and ruggedness and their great potential for application. In this article, I will review the various developments
in this field in roughly chronological order, and discuss some possible applications of this exciting phenomenon, also termed
as ‘random lasing’. 相似文献
65.
R.Justin RajeshPrem B Bisht 《Journal of luminescence》2002,99(3):301-309
Laser-induced transient grating technique has been used to measure the diffraction efficiency (η) and calculate the third-order nonlinear susceptibility (χ(3)) of some laser dyes. Theoretical simulations have been carried out on η and χ(3) as a function of wavelength covering the spectral range corresponding to the first excited singlet state of the dyes. Theoretically simulated values have been found in agreement to those observed experimentally. The decay profiles for these dyes have been measured by using diffraction of a delayed probe laser pulse to estimate the relaxation times in the excited state. 相似文献
66.
Parulekar SN Muppalla K Fronczek FR Bisht KS 《Chemical communications (Cambridge, England)》2007,(46):4901-4903
The synthesis and X-ray crystal structures of the first resorcin[4]arene cavitands by ring-closing metathesis reaction are described. 相似文献
67.
Varghese HT Yohannan Panicker C Philip D Mannekutla JR Inamdar SR 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,66(4-5):959-963
The IR and Raman spectra of methyl salicylate (MS) were recorded and analysed. Surface enhanced Raman scattering (SERS) spectrum was recorded in silver colloid. The vibrational wave numbers of the compound have been computed using the Hartree-Fock/6-31G* basis and compared with the experimental values. SERS studies suggest a flat orientation of the molecule at the metal surface. 相似文献
68.
A facile and efficient protocol is reported for the synthesis of calix[4]pyrroles and N-confused calix[4]pyrroles in moderate to excellent yields by reaction of dialkyl or cycloalkyl ketones with pyrrole catalyzed by reusable Amberlyst(TM)-15 under eco-friendly conditions. 相似文献
69.
Kuntrapakam Hema Rajesh G. Gonnade Prof. Kana M. Sureshan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(7):2919-2925
The synthesis of crystalline helical polymers of trehalose via topochemical azide–alkyne cycloaddition (TAAC) of a trehalose-based monomer is presented. An unsymmetrical trehalose derivative having azide and alkyne crystallizes in two different forms having almost similar packing. Upon heating, both the crystals undergo TAAC reaction to form crystalline polymers. Powder X-ray diffraction (PXRD) studies revealed that the monomers in both the crystals polymerize in a crystal-to-crystal fashion; circular dichroism (CD) studies of the product crystals revealed that the formed polymer is helically ordered. This solvent-free, catalyst-free polymerization method that eliminates the tedious purification of the polymeric product exemplifies the advantage of topochemical polymerization reaction over traditional solution-phase polymerization. 相似文献
70.
Dr. Kuntrapakam Hema Prof. Dr. Kana M. Sureshan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(23):8939-8944
Protein-mimics are of great interest for their structure, stability, and properties. We are interested in the synthesis of protein-mimics containing triazole linkages as peptide-bond surrogate by topochemical azide-alkyne cycloaddition (TAAC) polymerization of azide- and alkyne-modified peptides. The rationally designed dipeptide N3-CH2CO-Phe-NHCH2CCH ( 1 ) crystallized in a parallel β-sheet arrangement and are head-to-tail aligned in a direction perpendicular to the β-sheet-direction. Upon heating, crystals of 1 underwent single-crystal-to-single-crystal polymerization forming a triazole-linked pseudoprotein with Gly-Phe-Gly repeats. During TAAC polymerization, the pseudoprotein evolved as helical chains. These helical chains are laterally assembled by backbone hydrogen bonding in a direction perpendicular to the helical axis to form helical sheets. This interesting helical-sheet orientation in the crystal resembles the cross-α-amyloids, where α-helices are arranged laterally as sheets. 相似文献