Search results for "Interactions"
showing 10 items of 1963 documents
Strategies and Molecular Probes to Investigate the Role of Cytochrome P450 in Drug Metabolism
2003
Drug metabolism is the major determinant of drug clearance and, because of polymorphic or inducible expression of drug-metabolising cytochrome P450s (CYPs), is the factor most frequently responsible for interindividual differences in pharmacokinetics. A number of well characterised CYP substrates and inhibitors have been identified that allow precise measurements of individual CYP isoforms. Their use, alone or in combination, facilitates the phenotype characterisation of hepatocytes in vitro and in vivo. Two procedures are used for in vitro investigation of the metabolic profile of a drug: incubation with microsomes and incubation with metabolically competent cells. The major limitation of …
Toxicities by herbal medicines with emphasis to traditional Chinese medicine.
2011
It is estimated that three quarters of the world population rely on herbal and traditional medicine as a basis for primary health care. Therefore, it is one of the most important and challenging tasks for scientists working in drug research to investigate the efficacy of herbal medicine, to dissect favorable from adverse effects, to identify active principles in medicinal plants and to ban poisonous plants or contaminations from herbal mixtures. In the present review, some problems are critically discussed. Botanical misidentification or mislabeling of plant material can play a role for toxic reactions in humans. Some plant descriptions in traditional herbal medicine (e.g. traditional Chine…
Unprecedented multi-stable spin crossover molecular material with two thermal memory channels.
2013
et al.
Intervalley-scattering-induced electron-phonon energy relaxation in many-valley semiconductors at low temperatures
2005
We report on the effect of elastic intervalley scattering on the energy transport between electrons and phonons in many-valley semiconductors. We derive a general expression for the electron-phonon energy flow rate at the limit where elastic intervalley scattering dominates over diffusion. Electron heating experiments on heavily doped n-type Si samples with electron concentration in the range $3.5-16.0\times 10^{25}$ m$^{-3}$ are performed at sub-1 K temperatures. We find a good agreement between the theory and the experiment.
Nonadiabatic orientation, toroidal current, and induced magnetic field in BeO molecules.
2008
It is predicted that oriented BeO molecules would give rise to unprecedentedly strong, unidirectional electric ring current and an associated magnetic field upon excitation by a right or left circularly polarized laser pulse into the first excited degenerate singlet state. The strong toroidal electric ring current of this state is dominated by the ring current of the 1π± orbital about the molecular axis. Our predictions are based on the analysis of the orbital composition of the states involved and are substantiated by high level electronic structure calculations and wavepacket simulations of the laser-driven orientation and excitation dynamics. Luis.Serrano@uv.es
Recombination processes in unintentionally doped GaTe single crystals
2002
Emission spectra of GaTe single crystals in the range of 1.90–1.38 eV have been analyzed at different temperatures and excitation intensities by photoluminescence, photoluminescence excitation, and selective photoluminescence. A decrease in band gap energy with an increase in temperature was obtained from the redshift of the free exciton recombination peak. The energy of longitudinal optical phonons was found to be 14±1 meV. A value of 1.796±0.001 eV for the band gap at 10 K was determined, and the bound exciton energy was found to be 18±0.3 meV. The activation energy of the thermal quenching of the main recombination peaks and of the ones relating to the ionization energy of impurities and…
Optical pulling and pushing forces in bilayer PT-symmetric structures
2018
Photons are massless, yet can exert force on small particles. This $r\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}d\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}n$ $p\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}s\phantom{\rule{0}{0ex}}s\phantom{\rule{0}{0ex}}u\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}e$, though discussed by Kepler, still needs investigation for modern systems. This study reveals that the optical force exerted on a parity-time-symmetric bilayer with balanced gain and loss can be $a\phantom{\rule{0}{0ex}}s\phantom{\rule{0}{0ex}}y\phantom{\rule{0}{0…
Enhanced electron-transfer properties of cofacial porphyrin dimers through pi-pi interactions
2009
pi-pi assisted: Photoinduced electron transfer from cofacial porphyrin dimers to electron acceptors is prominently accelerated, whereas the back electron transfer is decelerated, relative to the corresponding porphyrin monomer (see figure).The radical cation of zinc tetrapentylporphyrin is dimerized with an excess of the neutral counterpart to form the dimer radical cation in which the unpaired electron is delocalized over both porphyrin rings. The dimeric radical cation exhibits an NIR absorption spectrum characteristic of weak pi-bond formation between the porphyrin rings. When cofacial porphyrin dimers, linked by different spacers, are oxidized such pi-bond formation between the porphyri…
Life in suspension and its impact on phytoplankton morphology: an homage to Colin S. Reynolds
2020
The amazing morphological diversity of phytoplankton has to be considered an evolutionarily driven compendium of strategies to cope with the strong variability and unpredictability of the pelagic environment. Phytoplankton collects unicellular and colonial photosynthetic organisms adapted to live in apparent suspension in turbulent water masses. Turbulence represents a key driver of phytoplankton dynamics in all aquatic ecosystems and phytoplankton morphological variability is the evolutionary response of this group of photosynthetic organisms to the temporal and spatial scales of variability of turbulence. This paper reviews the existing literature on the effects exerted by turbulence on p…
Solar neutrino detection in liquid xenon detectors via charged-current scattering to excited states
2020
We investigate the prospects for real-time detection of solar neutrinos via the charged-current neutrino-nucleus scattering process in liquid xenon time projection chambers. We use a nuclear shell model, benchmarked with experimental data, to calculate the cross sections for populating specific excited states of the caesium nuclei produced by neutrino capture on $^{131}$Xe and $^{136}$Xe. The shell model is further used to compute the decay schemes of the low-lying $1^{+}$ excited states of $^{136}$Cs, for which there is sparse experimental data. We explore the possibility of tagging the characteristic de-excitation $\gamma$-rays/conversion electrons using two techniques: spatial separation…