Results 1 - 10 of 1659
Results 1 - 10 of 1659. Search took: 0.017 seconds
|Sort by: date | relevance|
[en] Two morphologies of nanostructured tin dioxide (SnO2) (i.e., nanobelts and nanowires) were compressed in diamond anvil cells up to 38 GPa followed by decompression. In situ Raman spectroscopy and synchrotron X-ray diffraction were employed to monitor the structural transformations. It was found that nanostructured SnO2 behaved drastically differently than bulk material in terms of transformation pressures, phase stability regions and compressibility. These findings provide new insight into the unique pressure behaviours of nanostructured materials and have profound implications for producing controlled structures with new applications achieved by combined pressure-morphology tuning.
[en] A computational approach is presented for prediction and interpretation of core-level spectra of complex molecules. Applications are presented for several isolated organic molecules, sampling a range of chemical bonding and structural motifs. Comparison with gas phase measurements indicate that spectral lineshapes are accurately reproduced both above and below the ionization potential, without resort to ad hoc broadening. Agreement with experiment is significantly improved upon inclusion of vibrations via molecular dynamics sampling. We isolate and characterize spectral features due to particular electronic transitions enabled by vibrations, noting that even zero-point motion is sufficient in some cases
[en] We generalize earlier work [V.G. Stavros, E. Harel, S.R.Leone, J. Chem. Phys. 122 (2005) 064301] by illustrating the plausible role of ion gratings in time-dependent degenerate four-wave mixing (TD-DFWM) experiments in H2. We postulate that at high laser intensities (1014 1015 W/cm2), H2+/H+ ions generate a static ion grating, its signature manifested in the transformation from homodyne- to heterodyne-detection of the TD-DFWM signal, depending on laser intensity. The change in signal detection agrees with the calculated intensity for barrier suppression ionization (BSI) in H2 and the reported onset of saturation for H2+ and H+, pointing towards the likely role of ion gratings in intense laser field, FWM experiments
[en] Highlights: • Densities. • Resistivities. • Coefficients of expansion. • Enthalphies. • Show good agreement between calculated and observed. This paper briefly reviews the current “ions in a sea of electrons” model of metallic structure. Limitations of the model are stated. Properties not explained by the model are accounted for by an alternative model. Simple equations derived from this model can calculate the densities, resistivities, enthalpies of the Mx+ ions and coefficients of expansion of transition metals showing good agreement with experimental values. The alternative model is used to account for the ferro-magnetic properties of iron, cobalt and nickel and demonstrate why other transition metals are not magnetic but some lanthanides are magnetic.
[en] Highlights: • The bio-transformation of anticancer drug heptaplatin was studied by means of DFT. • Mono-adduct formation of purine bases with hydrolysed heptaplatin has been studied. • Guanine is favourable than adenine due to electronic factors and hydrogen-bonds. • Activation energies were compared with currently used Pt-based anticancer drugs. Heptaplatin is an approved platinum based cytostatic drug for the treatment of gastric cancers. The hydrolytic bio-transformation of Heptaplatin and the platination processes of guanine (G) and adenine (A) with resulting mono and di-aquated species of Heptaplatin have been investigated using density functional theory (DFT) combined with the conductor like dielectric continuum model (CPCM) approach, to spotlight the drug activation energy profiles and their binding mechanisms. The stationary points on the potential energy surfaces were fully optimized and characterized. The mono-functional binding of Heptaplatin, guanine as target over adenine due to electronic factors and more favorable hydrogen-bonds pattern.
[en] Highlights: • BALM is applied to optically image mature amyloid fibrils with a typical diameter of ∼14 nm FWHM. • BALM reveals a twisted ribbon-like substructure of amyloid fibrils and near-spherical shapes of oligomers. • While GSH enhances the fluorescence of NIAD-4, MEA exhibits strong interference. Application of BALM (binding activated localization microcopy) was shown to allow facile imaging of amyloid fibrils with a typical diameter of ∼14 nm FWHM. We also observed a twisted ribbon-like substructure of mutant amyloid fibrils and even what appear to be toxic amyloid oligomers with their characteristic morphological features consistent with TEM images. Use of an easily available staining dye in this method greatly enhances the prospect of addressing amyloid-related diseases in their diagnosis and drug tests by allowing facile in situ and in vivo detection by optical imaging.
[en] Highlights: • First determination of the UV absorption spectrum of 4H3H. • First measurement of the photolysis kinetics. • Estimation of the atmospheric lifetime of 4H3H by photolysis. The UV absorption spectrum and the photolysis reaction kinetics of 4-hydroxy-3-hexanone (4H3H) in the 275–330 nm region have been investigated for the first time. The photolysis frequency of this compound in the atmosphere was evaluated using actinometry and found to be J4H3H,atm = (5.9 ± 3.1) × 10−3 h−1. An atmospheric effective quantum yield was estimated to about 10% and a photolysis lifetime of about 7 days was determined. The comparison with the reactivity of other hydroxyketones suggests that the kinetics of hydroxyketones photolysis depends on their structure, mainly the branching and the proximity of the two functions.
[en] Highlights: • Low-lying electronic states of the AlC and GaC molecules. • Transition probabilities and radiative lifetime. • Molecular constants. The electronic states correlated to the first dissociation channel, around 25,500 cm−1, of the AlC and GaC molecules have been investigated by CASSCF/MRCI methodology with aug-cc-pV5Z basis set. Our work focused on the accurate description of the potential energy curves, dissociation energies, transition moment functions, radiative lifetimes, dipole moments and molecular constants. The B4Σ− electronic state has been previously detected for AlC molecule and it is probably not detectable in GaC molecule due to the predissociative character which affects all its vibrational levels. The characterization of the GaC low-lying electronic states were carried out for the first time.
[en] Highlights: • Plasmonic-layer-based DSSCs were prepared with Au and Ag nanoparticles. • Optimal conditions for immobilization of Au and Ag nanoparticles for the DSSC plasmonic layer were studied. • The DSSC with a plasmonic layer with Au and Ag nanoparticles exhibited better PCE than that without a plasmonic layer. We fabricated a plasmonic layer by immobilizing both Au and Ag nanoparticles via P4VP on a photoactive layer for dye-sensitized solar cells (DSSCs) to prevent aggregation of metal nanoparticles, to increase absorbance of N719 dye, and to enhance light harvesting and power conversion efficiency (PCE). The optimal conditions for immobilizing these nanoparticles were also examined. With plasmonic Au and Ag nanoparticles, the PCE increased by 8.05% and 5.78%, respectively (plasmonic Au nanoparticles: from 8.82% to 9.53%; plasmonic Ag nanoparticles: from 8.82% to 9.33%). When both Au and Ag nanoparticles were employed in the plasmonic layer, the PCE showed further improvement of 10.17%, corresponding to a 15.31% enhancement. This significant improvement of the PCE could be explained by a broader range of light absorption resulting from the presence of the plasmonic layer.
[en] Highlights: • Various complexities for ground and few low-lying excited states of CHA are pursued. • CLMC, CIS and a more generalised version of complexity using R, are explored. • CLMC with (R, E) explains the system better than corresponding (S, E) counterpart. • Importance of scaling factor b, on the nature of complexity measures is presented. Several well-known statistical measures similar to LMC and Fisher-Shannon complexity have been computed for confined hydrogen atom in both position (r) and momentum (p) spaces. Further, a more generalized form of these quantities with Rényi entropy (R) is explored here. The role of scaling parameter in the exponential part is also pursued. R is evaluated taking order of entropic moments as in r and p spaces. Detailed systematic results of these measures with respect to variation of confinement radius is presented for low-lying states such as, - and . For nodal states, such as and , as progresses there appears a maximum followed by a minimum in r space, having certain values of the scaling parameter. However, the corresponding p-space results lack such distinct patterns. This study reveals many other interesting features.