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71.
A new iridoid, shanzhiol (1), was isolated from the aerial parts of Mussaenda roxburghii. The structure was established by spectroscopic (including 2D NMR) and chemical methods. Shanzhiol (1) showed mild antibacterial activity against both Staphylococcus aureus and Escherichia coli with a MIC of 100 microg/mL by the broth dilution method. 相似文献
72.
Dinda B Debnath S Arima S Sato N Harigaya Y 《Chemical & pharmaceutical bulletin》2006,54(7):1030-1033
Four new iridoid glucosides, 5-dehydro-8-epi-adoxosidic acid, 5-dehydro-8-epi-mussaenoside, 10-O-dihydroferuloyldeacetyldaphylloside, and wendoside, together with one known iridoid glucoside, 8-epi-mussaenoside, beta-D-glucose, D-mannitol and beta-sitosterol have been isolated from the roots of Wendlandia tinctoria. On the basis of chemical and spectral analyses, the structures of new iridoid glucosides have been elucidated. 相似文献
73.
74.
The present work deals with a detailed study of universal thermodynamics in different modified gravity theories. The validity of the generalized second law of thermodynamics (GSLT) and thermodynamical equilibrium (TE) of the Universe bounded by a horizon (apparent/event) in f(R)-gravity, Einstein–Gauss–Bonnet gravity, RS-II brane scenario and DGP brane model has been investigated. In the perspective of recent observational evidences, the matter in the Universe is chosen as interacting holographic dark energy model. The entropy on the horizons is evaluated from the validity of the unified first law and as a result there is a correction (in integral form) to the usual Bekenstein entropy. The other thermodynamical parameter namely temperature on the horizon is chosen as the recently introduced corrected Hawking temperature. The above thermodynamical analysis is done for homogeneous and isotropic flat FLRW model of the Universe. The restrictions for the validity of GSLT and the TE are presented in tabular form for each gravity theory. Finally, due to complicated expressions, the validity of GSLT and TE are also examined from graphical representation, using three Planck data sets. 相似文献
75.
Debattam Sarkar Dr. Tanmoy Ghosh Dr. Ananya Banik Dr. Subhajit Roychowdhury Prof. Dirtha Sanyal Prof. Kanishka Biswas 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(27):11208-11215
A two-step optimization strategy is used to improve the thermoelectric performance of SnTe via modulating the electronic structure and phonon transport. The electrical transport of self-compensated SnTe (that is, Sn1.03Te) was first optimized by Ag doping, which resulted in an optimized carrier concentration. Subsequently, Mn doping in Sn1.03−xAgxTe resulted in highly converged valence bands, which improved the Seebeck coefficient. The energy gap between the light and heavy hole bands, i.e. ΔEv decreases to 0.10 eV in Sn0.83Ag0.03Mn0.17Te compared to the value of 0.35 eV in pristine SnTe. As a result, a high power factor of ca. 24.8 μW cm−1 K−2 at 816 K in Sn0.83Ag0.03Mn0.17Te was attained. The lattice thermal conductivity of Sn0.83Ag0.03Mn0.17Te reached to an ultralow value (ca. 0.3 W m−1 K−1) at 865 K, owing to the formation of Ag7Te4 nanoprecipitates in SnTe matrix. A high thermoelectric figure of merit (z T≈1.45 at 865 K) was obtained in Sn0.83Ag0.03Mn0.17Te. 相似文献
76.
P. Tchofo Dinda J. Atangana A. Kamagate A. Labruyère T. C. Kofane 《The European physical journal. Special topics》2009,173(1):121-138
We address the problem of characterization of light pulses that propagate in long-haul high-bit-rate optical communication
systems, under strongly perturbed conditions. We show that the conventional technique for characterization of the phase and
intensity profile of such pulses becomes qualitatively inconsistent when the pulse’s profile is asymmetrically distorted with
respect to its center-of-mass. We resolve these inconsistencies by partially reformulating the conventional technique by means
of appropriate pulse parameters, which we call upgraded parameters, which allow a fair characterization of the intensity and phase of all types of light pulses, including those which are asymmetrically
distorted. We illustrate the effectiveness of the upgraded parameters by applying them to a meticulous characterization of light pulses in a dispersion-managed optical fiber system in which third-order
dispersion is acting as a strong perturbation. 相似文献
77.
Arunabha Sen Subhajit Dutta Gourab K. Dam Dr. Partha Samanta Sumanta Let Dr. Shivani Sharma Dr. Mandar M. Shirolkar Prof. Sujit K. Ghosh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(53):13442-13449
Fabricating new and efficient materials aimed at containment of water contamination, in particular removing toxic heavy metal based oxo-anions (e. g. CrO42−, TcO4−) holds paramount importance. In this work, we report two new highly stable imidazolium based ionic porous organic polymers (iPOPs) decorated with multiple interaction sites along with electrostatics driven adsorptive removal of such oxo-anions from water. Both the iPOPs (namely, iPOP-3 and iPOP-4) exhibited rapid sieving kinetics and very high saturation uptake capacity for CrO42− anions (170 and 141 mg g−1 for iPOP-3 and iPOP-4 respectively) and ReO4− (515.5 and 350.3 mg g−1 for iPOP-3 and iPOP-4 respectively), where ReO4− anions being the non-radioactive surrogative counterpart of radioactive TcO4− ions. Noticeably, both iPOPs showed exceptional selectivity towards CrO42− and ReO4− even in presence of several other concurrent anions such as Br−, Cl−, SO42−, NO3− etc. The theoretical binding energy calculations via DFT method further confirmed the preferential interaction sites as well as binding energies of both iPOPs towards CrO42− and ReO4− over all other competing anions which corroborates with the experimental high capacity and selectivity of iPOPs toward such oxo-anions. 相似文献
78.
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
79.
This article uses projection depth (PD) for robust classification of multivariate data. Here we consider two types of classifiers,
namely, the maximum depth classifier and the modified depth-based classifier. The latter involves kernel density estimation,
where one needs to choose the associated scale of smoothing. We consider both the single scale and the multi-scale versions
of kernel density estimation, and investigate the large sample properties of the resulting classifiers under appropriate regularity
conditions. Some simulated and real data sets are analyzed to evaluate the finite sample performance of these classification
tools. 相似文献
80.
Subhajit Chakraborty Dr. Somen Nandi Dr. Kankan Bhattacharyya Dr. Saptarshi Mukherjee 《Chemphyschem》2019,20(23):3221-3227
In this work, we propose a new analysis of the time resolved emission spectra of a photo-acid, HA, pyranine (8-hydroxypyrene-1,3,6-trisulphonic acid, HPTS) based on time resolved area normalized emission spectra (TRANES). Presence of an isoemissive point in TRANES confirms the presence of two emissive species (HA and A−) inside the system in bulk water and inside a co-polymer hydrogel [F127, (PEO)100–(PPO)70–(PEO)100]. We show that following electronic excitation, the local pH around HPTS, is much lower than the bulk pH presumably because of ejection of proton from the photo-acid in the excited state. With increase in time, the local pH increases and reaches the bulk value. We further, demonstrate that the excited state pKa of HPTS may be estimated from the emission intensities of HA and A− at long time. The time constant for time evolution of pH is ∼630 ps in water, ∼1300 ps in F127 gel and ∼4700 ps in CTAB micelle. The location and local viscosity sensed by the probe is ascertained using fluorescence correlation spectroscopy (FCS) and fluorescence anisotropy decay. The different values of the local viscosity reported by these two methods are reconciled. 相似文献