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991.
Poonam Tandon V. D. Gupta O. Prasad Shantanu Rastogi S. B. Katti 《Journal of Polymer Science.Polymer Physics》1996,34(7):1213-1228
Poly(β-benzyl-L-aspartate) (PBLA) is an unusual polypeptide, which is capable of going into four different conformations, namely, left-handed α helix, right-handed α helix, ω helix, and β pleated sheet. The present work is a complete study of normal modes and their dispersion in the unusual left-handed α form. A special feature of some of the dispersion curves is their tendency to bunch in the neighborhood of helix angle. This is attributed to the presence of strong intramolecular interactions. Crossing and repulsion between the dispersion curves is also observed. The N-deuterated analogue of PBLA has been studied to check the validity of assignments and force field (Urey Bradley). Specific heat has been obtained from dispersion curves via density of states. A comparative study of left-handed and right-handed forms is presented. © 1996 John Wiley & Sons, Inc. 相似文献
992.
Bagineni Prasad Mara Doimo Mns Andrasson Valentin LHte Erik Chorell Sjoerd Wanrooij 《Chemical science》2022,13(8):2347
G-quadruplex (G4) DNA structures are implicated in central biological processes and are considered promising therapeutic targets because of their links to human diseases such as cancer. However, functional details of how, when, and why G4 DNA structures form in vivo are largely missing leaving a knowledge gap that requires tailored chemical biology studies in relevant live-cell model systems. Towards this end, we developed a synthetic platform to generate complementary chemical probes centered around one of the most effective and selective G4 stabilizing compounds, Phen-DC3. We used a structure-based design and substantial synthetic devlopments to equip Phen-DC3 with an amine in a position that does not interfere with G4 interactions. We next used this reactive handle to conjugate a BODIPY fluorophore to Phen-DC3. This generated a fluorescent derivative with retained G4 selectivity, G4 stabilization, and cellular effect that revealed the localization and function of Phen-DC3 in human cells. To increase cellular uptake, a second chemical probe with a conjugated cell-penetrating peptide was prepared using the same amine-substituted Phen-DC3 derivative. The cell-penetrating peptide conjugation, while retaining G4 selectivity and stabilization, increased nuclear localization and cellular effects, showcasing the potential of this method to modulate and direct cellular uptake e.g. as delivery vehicles. The applied approach to generate multiple tailored biochemical tools based on the same core structure can thus be used to advance the studies of G4 biology to uncover molecular details and therapeutic approaches.The development of an approach to generate multiple tailored biochemical tools based on the same core structure, Phen-DC3, to advance studies of G4 biology to uncover molecular details and therapeutic approaches. 相似文献
993.
Mannan Zubaer Ibna Adhikari Shyam Prasad Kim Hyongsuk Chua Leon 《Nonlinear dynamics》2020,99(4):3169-3196
Nonlinear Dynamics - This paper presents an in-depth and rigorous mathematical analysis of a family of nonlinear dynamical circuits whose only nonlinear component is a Chua Corsage Memristor (CCM)... 相似文献
994.
Solvent extraction of Zr(IV) from aqueous HCl solutions by mixtures of TOA and different organophosphorous bases in carbontetrachloride
solvent have been found to be always higher than that by any single extractant. Synergism has been observed in the range of
2.4–9.6M HCl. Although the species extracted with neutral donor alone seems to be ZrCl4·TOPO etc, with a mixture of extractants, however, the extracted species appears to be Q2ZrCl6·TOPO where Q is R3NH. The extraction has also been found to increase with increase in the concentration of amines and neutral donors. Enhancement
of extraction has been explained by the formation of a complex adduct in organic phase. Synergistic coefficients and apparent
formation constants of the complex adducts have also been calculated. 相似文献
995.
1,3-Diaryl-4-pyrazoleacetic acids and derivatives exhibit multiple biological activities.1 For example, Lonazolac® is listed in Merck index as an antiinflammatory and analgesic agent. We were interested in this type of compounds for their potential applications in anti-diabetics. One of the leading candidates, SDZ RGU 825,has been shown to enhance whole-body glucose disposal without increasing insulin secretion. Therefore, it was developed for treatment of "non-insulin-dependent diabetes mellitus",the type Ⅱ diabetics. 相似文献
996.
Abdulrahman I. Almansour Natarajan Arumugam Saradh Prasad Raju Suresh Kumar Mohamad S. Alsalhi Manal Fahad Alkaltham Haya bint Abdulaziz Al-Tamimi 《Molecules (Basel, Switzerland)》2022,27(1)
Quinoline Schiff bases display potential applications in optoelectronics and laser fields because of their unique optical properties that arise from extensive delocalization of the electron cloud, and a high order of non-linearity. In this context, a new class of conjugated quinoline-derivative viz. N-(quinolin-3-ylmethylene)anilines were synthesized from 2-hydroxyquinoline-3-carbaldehyde in two good yielding steps. The ability of these imines to accept an electron from a donor is denoted by their electron acceptor number and sites, which is calculated using density functional theory (DFT). The optical properties such as FT-IR, Raman, UV-VIS, and EDS spectra were calculated using TD-DFT, which also provided the energy gap, HOMO-LUMO structure. The optical properties of the synthesized imino quinolines were experimentally studied using photoluminescence and absorption spectroscopy. The properties such as Stokes shift and quantum yield were calculated using experimental data. Furthermore, the compound bearing a methyl group on the aryl ring and ZnO nanoparticles (hydrothermally synthesized) were dissolved in toluene, and optically excited with a 355 nm nanosecond laser, which produced a random laser. 相似文献
997.
A. Shailos M. El Hassan C. Prasad J. P. Bird D. K. FerryL. -H. Lin N. Aoki K. Nakao Y. OchiaiK. Ishibashi Y. AoyagiT. Sugano 《Superlattices and Microstructures》2000,27(5-6)
We present evidence for a re-entrant metal–insulator transition that arises in quantum dot arrays as the gate voltage is used to sweep their density of states past the Fermi level. The form of the temperature variation of the conductance observed in these arrays can be accounted for using a functional form derived from studies of the metal–insulator transition in two dimensions, although the values obtained for the fit parameters suggest that the behavior we observe here may be quite distinct to that found in two dimensions. 相似文献
998.
Stereoscopic particle image velocimetry 总被引:25,自引:19,他引:6
A. K. Prasad 《Experiments in fluids》2000,29(2):103-116
Stereoscopic particle image velocimetry (PIV) employs two cameras to record simultaneous but distinct off-axis views of the
same region of interest (illuminated plane within a flow seeded with tracer particles). Sufficient information is contained
in the two views to extract the out-of-plane motion of particles, and also to eliminate perspective error which can contaminate
the in-plane measurement. This review discusses the principle of stereoscopic PIV, the different stereoscopic configurations
that have been used, the relative error in the out-of-plane to the in-plane measurement, and the relative merits of calibration-based
methods for reconstructing the three-dimensional displacement vector in comparison to geometric reconstruction. It appears
that the current trend amongst practitioners of stereoscopic PIV is to use digital cameras to record the two views in the
angular displacement configuration while incorporating the Scheimpflug condition. The use of calibration methods has also
gained prominence over geometric reconstruction.
Received: 15 April 1999/Accepted: 1 February 2000 相似文献
999.
S. Basu 《Czechoslovak Mathematical Journal》2000,50(1):59-65
Steinhaus [9] prove that if a set A has a positive Lebesgue measure in the line then its distance set contains an interval. He obtained even stronger forms of this result in [9], which are concerned with mutual distances between points in an infinite sequence of sets. Similar theorems in the case we replace distance by mutual ratio were established by Bose-Majumdar [1]. In the present paper, we endeavour to obtain some results related to sets with Baire property in locally compact topological spaces, particular cases of which yield the Baire category analogues of the above results of Steinhaus [9] and their corresponding form for ratios by Bose-Majumdar [1]. 相似文献
1000.
T. Misra T. Ganguly S. Kamila C. Basu A. De 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2001,57(14):1037-2808
Synthesis, characterization, steady state and time resolved, using time correlated single photon counting as well as laser flash photolysis techniques, spectroscopic investigations were made for two alkoxy benzo[b]thiophene molecules: 5-methoxy benzo[b]thiophene (5MBT) and 5-methoxymethyl benzo[b]thiophene (5MMBT). In both non-polar n-heptane (NH) and polar acetonitrile (ACN) solvents and at ambient temperature the electronic absorption spectra of these thiophenes exhibit different band systems whose assignments were made from the measurements of the steady state excitation polarization spectra. Steady state fluorescence spectra of these molecules in the different polarity solvents show the presence of non-specific interactions. From the redox properties of the benzothiophenes, measured by cyclic voltammetry, their electron donating properties were observed in the presence of the well-known electron acceptor 9cyanoanthracene (9CNA). Further, detailed studies by laser flash photolysis techniques show that ion-recombination mechanism predominates after the initial excitation of the acceptor moiety using the third harmonic of Nd:YAG laser. This recombination together with the external heavy atom effect (the donor containing 'sulphur' atom) appears to be responsible for the formation of the triplet of the monomeric acceptor 9CNA. From the steady state experiments it is shown that both in non-polar NH and highly polar ACN the quenching in the fluorescence emission of 9CNA in the presence of the benzothiophene donors is brought about primarily by the external heavy atom effect and in ACN, although the presence of the photoinduced ET reaction is confirmed, this process seems, from the observed bimolecular dynamic quenching rate, kq to be significantly masked by the external heavy atom effect. 相似文献