1,721,055 research outputs found
Ab-initio phonon calculations for the layered compound TiOCl
No full textWe present first-principles frozen-phonon calculations for the three Raman-active Ag modes in the spin-1/2-layered TiOCl system within two different well-known approaches: the local-density approximation
sLDAd and the so-called LDA+U approximation. We observe that the inclusion of electron correlation in a
mean-field level as implemented in the LDA+U leads to a better overall agreement with experimental results.
We also discuss the implications of the two approaches on the physics of TiOCl
4-Hydroxycoumarins as Michael donors in asymmetric routes to polycyclic coumarins (microreview)
No full textDifferent [3,4]-fused polycyclic 2H-chromen-2-ones can be prepared in a stereoselective fashion
starting from 4-hydroxycoumarins as nucleophilic synthones. Herein we report a brief overview of the
most recent methods including Pd-catalyzed [3+3] annulation processes, organocatalytic one-pot and
domino Michael addition/cyclization, tandem conjugate addition/hydroxyalkylation, and organocascade catalytic reaction
Effects of the GMB correction on the critical temperature and gap parameter throughout the BCS-BEC crossover
No full textIt has long been known that the critical temperature and gap parameter of a BCS weak-coupling superfluid are considerably reduced by the inclusion of the Gorkov-Melik-Barkhudarov (G-MB) correction, whereby particle-hole excitations screen the two-fermion effective interaction in the medium. We have extended the effects of the G-MB correction throughout the whole BCS-BEC crossover by identifying the Feynman diagrams responsible for the G-MB correction in both the normal and superfluid phases. The numerical solution of the resulting equations yield results for the critical temperature and gap which agree very well with Quantum Monte Carlo and experimental data in the crossover regio
Boson-fermion pairing and condensation in two-dimensional Bose-Fermi mixtures
Full text linkWe consider a mixture of bosons and spin-polarized fermions in two dimensions at zero temperature with a tunable Bose-Fermi attraction. By adopting a diagrammatic T-matrix approach, we analyze the behavior of several thermodynamic quantities for the two species as a function of the density ratio and coupling strength, including the chemical potentials, the momentum distribution functions, the boson condensate density, and the Tan's contact parameter. By increasing the Bose-Fermi attraction, we find that the condensate is progressively depleted and Bose-Fermi pairs form, with a small fraction of condensed bosons surviving even for strong Bose-Fermi attraction. This small condensate proves sufficient to hybridize molecular and atomic states, producing quasi-particles with unusual Fermi liquid features. A nearly universal behavior of the condensate fraction, the bosonic momentum distribution, and Tan's contact parameter with respect to the density ratio is also found
Monoamine Oxidase Inhibition for the Treatment of Neurodegenerative Diseases: Rationale, Assay Methodologies, and Reference Compounds
No full textMonoamine oxidases (MAOs) A and B are key enzymes involved in the metabolism of amine neurotransmitters as well as exogenous amine-containing substances. Since their characterization in the 1960s, they represent a pharmacological target for the discovery of small molecular inhibitors, especially as antidepressants and antiparkinsonian drugs. The development of in vitro/in vivo assays has paralleled such interest allowing the setup of fast and reliable screening methods herein described. Hence, a huge number of potent and selective inhibitors have been discovered, although only in some cases reaching the pharmaceutical market. A renewed interest has emerged with the so-called multitarget approach, combining multiple biological activities in a single molecular entity, speeding up the screening of MAO inhibitors endowed with additional activities for the treatment of neurodegenerative diseases
Effects of Fe substitution on the electronic, transport, and magnetic properties of ZnGa2O4: A systematic ab initio study
No full textWe present a density functional study of Fe doped into the tetrahedral and octahedral cation sites of the wide-band-gap spinel ZnGa2O4. We calculate the electronic structure for different substitutions and discuss the magnetic and transport properties for each case considering different approximations for the exchange-correlation potential. We show that for certain doped cases, significant differences in the predicted behavior are obtained depending on the exchange-correlation potential adopted. Possible applications of the doped systems as magnetic semiconductors are outlined
Synthesis of 5-Aroyldihydropyrimidinones via Liebeskind–Srogl Thiol Ester– Boronic Acid Cross-Couplings
No full textJosephson Critical Currents and Related Effects in Ultracold Atomic Superfluid Sytems
Full text linkThe Josephson and Proximity effects play a pivotal role in the design of superconducting devices for the implementation of quantum technology, ranging from the standard Al based to the more exotic twisted high-Tc junctions. Josephson critical currents have been recently investigated also in ultracold atomic systems where a potential barrier acts as a weak link. The unifying feature of the above systems, apart from being superconducting/superfluid, is the presence of spatial inhomogeneity, a feature that has to be properly taken into account in any theoretical approach employed to investigate them. In this work, we review the novel (dubbed LPDA for Local Phase Density Approximation) approach based on a coarse graining of the Bogoliubov–de Gennes (BdG) equations. Non-local and local forms of this coarse graining were utilized when investigating Proximity and Josephson effects. Moreover, the LPDA approach was further developed to include pairing fluctuations at the level of the non-self-consistent t-matrix approximation. The resulting approach, dubbed mLPDA (modified LPDA), can be used whenever inhomegeneity and fluctuations effects simultaneously play an important role
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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