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91.
Lavarello RJ Ghoshal G Oelze ML 《The Journal of the Acoustical Society of America》2011,129(5):2903-2911
The ultimate goal of quantitative ultrasound (QUS) imaging methods based on backscatter coefficient (BSC) estimates is to obtain system-independent structural information about samples. In the current study, three BSC estimation methods were compared and evaluated using the same backscattered pressure datasets in order to assess their consistency. BSC estimates were obtained from two phantoms with embedded glass spheres and compared to theoretical BSCs calculated using size distributions estimated using optical microscopy. Effective scatterer diameter and concentration estimates of the glass spheres were also obtained from the estimated BSCs. One estimation method needed to be compensated by more than an order of magnitude in amplitude in order to produce BSCs comparable to the other two methods. All calibration methods introduced different frequency-dependent effects, which could have noticeable effects on the bias of QUS estimates derived from experimental BSCs. Although in most cases the experimental QUS estimates obtained with all three methods were observed to differ by less than 10%, larger differences are expected depending on both the pressure focusing gain of the transducer (proportional to the ratio of the square of the aperture radius to the product of the wavelength and focal length) and ka range used in the estimation. 相似文献
92.
JPC – Journal of Planar Chromatography – Modern TLC - A reversed-phase high-performance thin-layer chromatography (RP-HPTLC) method was developed for the determination of flavonoids... 相似文献
93.
Cu-doped LiCaBO3 phosphors were prepared by modified solid-state synthesis and the formation of compound was confirmed by X-ray diffraction study. LiCaBO3:Cu+ (Cu?=?0.02, 0.05, 0.1 and 0.2?mol%) were studied for photoluminescence (PL) study and prominent PL emission spectra were obtained for Cu+ with transition 3d94s1?→?3d10. The phosphors were further studied by thermoluminescence (TL) property for exposure to γ-ray irradiation of 1.2?rad with 137Cs source. TL of LiCaBO3:Cu was also studied for C5+ (3.75?×?1012?ion?cm?2) beam irradiation for 1?min exposure time. Trapping parameters (activation energy and frequency factor) for single deconvoluted peaks were obtained by Chen's peak shape method. 相似文献
94.
S. Nayek A. Ghoshal 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,64(2-3):257-268
We have made an investigation on H(ns) → H(n′ s) transition processes by positron impact with screened Coulomb potentials (SCP) by employing a distorted-wave formalism in the momentum space. Making use of simple variational wave functions of the hydrogen atom interacting with SCP we have been able to obtain the partial-wave scattering amplitudes in closed analytical forms. We have then used these distorted-wave scattering amplitudes to make a detailed study on differential and total cross sections in the energy range 20–300 eV. This study reveals some hitherto unknown features of the differential and total cross section. To the best of our knowledge such a study on the differential and total cross sections for inelastic positron-hydrogen collisions with SCP is reported for the first time in the literature. 相似文献
95.
Theoretical and Mathematical Physics - To a modular form, we propose to associate $$($$ an infinite number of $$)$$ complex-valued functions on $$p$$ -adic numbers $$\mathbb{Q}_p$$ for each prime... 相似文献
96.
Arijit Halder Dr. Biswajit Bhattacharya Fazle Haque Susanta Dinda Dr. Debajyoti Ghoshal 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(52):12196-12205
A pair of supramolecular isomers of CdII-based MOF have been synthesized by utilizing a flexible N,N′-donor linker and a dicarboxylate with ESIPT (excited-state intramolecular proton transfer) fluorophore by varying the reaction media. One of the MOFs has a 3D four-fold interpenetrating framework with guest solvent in the structure that undergoes a solvent-dependent crystalline-to-crystalline structural transformation, which has been extensively studied by powder XRD and IR spectroscopy. The other MOF is structurally rigid in nature and has a two-fold interpenetrating structure without any guest molecules. Both the compounds show moderate CO2 adsorption and one of them, the MOF with the four-fold interpenetrating structure, also shows moderately high H2 adsorption. Furthermore, both the compounds show interesting luminescence behavior. In the solid state, the two compounds show single-peak spectra, whereas upon suspension of these compounds in polar solvents, the maxima split into two peaks with a large Stokes shift. On the other hand, in nonpolar solvents, only one emission maximum is observed. This solvatochromic dual-emission phenomenon is due to ESIPT, which has been extensively studied. 相似文献
97.
Srinivas Lavanya Kumar Manda Shashank Tripathi Anirban Ghoshal Mayur D. Ambule Dr. Ajay Kumar Srivastava Dr. Gautam Panda 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(23):5131-5156
Macrocyclic alkaloids (macrolides) and cyclopeptides have an immense range of applications in drug discovery research because of their natural abundance and potential biological and physicochemical properties. Presently, more than 100 approved drugs or clinical drug candidates contain macrocyclic scaffolds as the biologically active component. This review provides an interesting perspective about the use of amino acid-derived chiral pools versus other methods derived from miscellaneous synthons towards the total synthesis of non-peptidic macrolides. The synthetic routes and the key strategies involved in the total syntheses of ten natural macrolides have been discussed. Both the amino acid-derived and non-amino acid-derived synthetic routes have been illustrated to present a comparative study between the two approaches. 相似文献
98.
We have synthesized 7-fluoro-, 9-fluoro- and 11-fluoro- benzo[b]fluoranthene as part of a study designed to locate the molecular sites involved in the metabolic activation of the carcinogenic parent hydrocarbon. Analysis of the proton NMR spectra reveals the effect of fluorine substitution to be almost entirely localized in the substituted ring, the principal exception being a strong deshielding of opposing protons in sterically crowded sites (, peri or pseudo-bay regions). 相似文献
99.
pH and temperature play critical roles in multistep enzymatic conversions. In such conversions, the optimal pH for individual
steps differs greatly. In this article, we describe the production of glucoamylase (from Aspergillus oryzae MTCC152 in solid-state fermentation) and glucose isomerase (from Streptomyces griseus NCIM2020 in submerged fermentation), used in industries for producing high-fructose syrup. Optimum pH for glucoamylase was
found to be 5.0. For glucose isomerase, the optimum pH ranged between 7.0 and 8.5, depending on the type of buffer used. Optimum
temperature for glucoamylase and glucose isomerase was 50 and 60°C, respectively. When both the enzymatic conversions were
performed simultaneously at a compromised pH of 6.5, both the enzymes showed lowered activity. We also studied the kinetics
at different pHs, which allows the two-step reaction to take place simultaneously. This was done by separating two steps by
a thin layer of urease. Ammonia generated by the hydrolysis of urea consumed the hydrogen ions, thereby allowing optimal activity
of glucose isomerase at an acidic pH of 5.0. 相似文献
100.
A. Ghoshal P. Mandal 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(2):327-335
e+ + H(ns) ↦e+ + H(n′s) transitions for arbitrary n and
n′ have been studied using the distorted-wave formalism in the
momentum space [Ghoshal and Mandal, Phys. Rev. A 72, 032714 (2005)]. The distorted-wave
scattering amplitudes have been written in a simple closed analytical form. A detailed
study has been made on differential and total cross sections in the energy range 20–300 eV.
Resonance-like behaviour of the
differential cross section has been observed in the the region of lower scattering angles
for high Rydberg transitions. To the best of our knowledge the distorted-wave results for
differential and total cross sections for such arbitrary transitions are reported for the
first time in the literature. 相似文献