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81.
The phonon properties and thermodynamics of four crystalline cellulose allomorphs, I, I, II, and III, have been investigated using dispersion-corrected density functional theory (DFT). In line with experimental findings, the free energy differences between the studied cellulose allomorphs are small, less than 1 kJ/mol per atom. The calculated specific heat at constant volume () has been compared with the available experimental data in the temperature range 10–300 K. Quasiharmonic approximation has been employed to study thermodynamics and specific heat at constant pressure (). For the studied temperature range of 10–400 K, the specific heat of all cellulose allomorphs shows very similar behavior. The calculated and experimental specific heat agree well at low temperatures below 100 K, but the deviation between theory and experiment increases with temperature. This may be due to increasing phonon anharmonicity as the temperature increases. 相似文献
82.
K. Swathi Meleppatt Sujith P. S. Divya Merin Varghese P Andrea Delledonne D. K. Andrea Phan Huu Francesco Di Maiolo Francesca Terenziani Andrea Lapini Anna Painelli Cristina Sissa K. George Thomas 《Chemical science》2023,14(8):1986
The phenomenon of excited-state symmetry breaking is often observed in multipolar molecular systems, significantly affecting their photophysical and charge separation behavior. As a result of this phenomenon, the electronic excitation is partially localized in one of the molecular branches. However, the intrinsic structural and electronic factors that regulate excited-state symmetry breaking in multibranched systems have hardly been investigated. Herein, we explore these aspects by adopting a joint experimental and theoretical investigation for a class of phenyleneethynylenes, one of the most widely used molecular building blocks for optoelectronic applications. The large Stokes shifts observed for highly symmetric phenyleneethynylenes are explained by the presence of low-lying dark states, as also established by two-photon absorption measurements and TDDFT calculations. In spite of the presence of low-lying dark states, these systems show an intense fluorescence in striking contrast to Kasha''s rule. This intriguing behavior is explained in terms of a novel phenomenon, dubbed “symmetry swapping” that describes the inversion of the energy order of excited states, i.e., the swapping of excited states occurring as a consequence of symmetry breaking. Thus, symmetry swapping explains quite naturally the observation of an intense fluorescence emission in molecular systems whose lowest vertical excited state is a dark state. In short, symmetry swapping is observed in highly symmetric molecules having multiple degenerate or quasi-degenerate excited states that are prone to symmetry breaking.Highly symmetric multibranched phenyleneethynylenes exhibit intense fluorescence despite the presence of low-lying dark states. The inversion of the energy order of excited states is explained in terms of a novel phenomenon dubbed “symmetry swapping”. 相似文献
83.
84.
Pradeep Savitha Devaswamparambil Sebastian Deepa Gopalakrishnan Anjali Krishna Manoharan Divya Kizhakkeppurath Madhusudhanan Dhanya Thaikatt Mohanan Puzhavoorparambil V. 《Journal of fluorescence》2021,31(4):1113-1123
Journal of Fluorescence - A heterocyclic Schiff base (MPDPI)was synthesized by the condensation reaction of 1-phenylisatin with 4,5-dimethylphenylene diamine. It was characterized by using... 相似文献
85.
The γ- and conversion electron spectra following131Ba ε-decay are investigated, using HPGe detector and mini-orange electron spectrometer. Attention is particularly focussed
on identifying weak transitions associated with low energy high spin levels in131Cs level scheme earlier inferred in reaction studies but not yet observed in131Ba decay. Our experiment identifies 15 new gammas and 6 new conversion lines in this decay. Internal conversion coefficients
and multipolarities of several transitions are determined. Five new levels (3 with Iπ = 7/2+ and one each with Iπ 9/2+ and 11/2−) are introduced in the131Cs level scheme based on our observations taken together with the results from reaction studies. Spin-parity assignments to
a few other levels are also suggested 相似文献
86.
The flow of various liquids and gases over single-walled carbon nanotube bundles induces an electrical signal (voltage/current)
in the sample along the direction of the flow. The electrical response generated by the flow of liquids is found to be logarithmic
in the flow speed over a wide range. In contrast, voltage generated by the flow of gas is quadratically dependent on the gas
flow velocity. It was found that the underlying physics for the generation of electrical signals by liquids and gases are
different. For the liquid, the Coulombic interaction between the ions in the liquid and the charge carriers in the nanotube
plays a key role while electrical signal generation due to gas flow is due to an interplay of Bernoulli’s principle and Seebeck
effect. Unlike the liquid case which is specific to the nanotubes, the gas flow effect can be seen for a variety of solids
ranging from single and multi-walled carbon nanotubes, graphite and doped semiconductors. 相似文献
87.
Residual interaction calculations have been made for predicting the sign and the magnitude of the odd-even shifts observed
in the rotational levels of theK=0 bands in the doubly-odd rare earth nuclei. It is shown that, contrary to the conclusions reached in earlier studies, the
same zero-range spin-dependent residual interaction can reproduce the odd-even shifts as well as the GM splitting energies.
This has been made possible with the inclusion of the phase factors for the total intrinsic spin and the total parity of the
two-quasi-particle states in the Newby matrix elements. Predictions are made for the odd-even shifts for otherK=0 bands arising from several configurations not confirmed or observed so far. 相似文献
88.
M. S. Hundal Geeta Sood Parveen Kapoor S. S. Tandon 《Journal of chemical crystallography》1988,18(5):601-607
The title compound C18H18N2O2S is monoclinic with unit-cell dimensionsa=8.849(10),b=9.185(11),c=20.257(9) Å,=109.28(10)°. The space group isP21/c, withZ=4. Data were measured by photographic methods. The structure was solved by direct methods. A full-matrix least-squares refinement converged toR=0.10. All atoms except sulfur were assigned individual isotropic thermal parameters. The conformation of the thiadiazepine ring system is distorted boat shaped, as indicated by torsion angle studies. 相似文献
89.
Nitish Kumar Divya Shikha Swati Kumari Binod Kumar Choudhary Lokendra Kumar Indu Shekhar Singh 《Applied biochemistry and biotechnology》2018,185(1):34-41
Euryale ferox is native to Southeast Asia and China, and it is one of the important aquatic food crops propagated mostly in eastern part of India. The aim of the present study was to characterize and evaluate the genetic diversity of ex situ collections of E. ferox germplasm from different geographical states of India using microsatellite (simple sequence repeats (SSRs)) markers. Ten SSR markers were analyzed to assess DNA fingerprinting and genetic diversity of 16 cultivated germplasm of E. ferox. Total 37 polymorphic alleles were recorded with an average of 3.7 allele frequency per primer. The polymorphic information content value varied from 0.204 to 0.735 with mean of 0.448. A high range of heterozygosity (Ho 0.228; He 0.512) was detected in the present study. The neighbor-joining (N-J) tree and the principle coordinate analysis showed that the germplasm divided in to three main clusters. The results of the present investigation comply that SSR markers are effective for computing genetic assessment of genetic diversity and similarity with classifying cultivated varieties of E. ferox. Evaluation of genetic diversity among Indian E. ferox germplasm could provide useful information for genetic improvement. 相似文献
90.
Mehta Kashish Jha Mithilesh Kumar Divya Neetu 《Research on Chemical Intermediates》2018,44(12):7691-7709
Research on Chemical Intermediates - Rapid industrialisation and hike in fuel prices has led to a growing concern for the development of alternative fuel from renewable sources. Biodiesel is one of... 相似文献