Spectroscopic comprehension of Mott-Hubbard insulator to negative charge transfer metal transition in LaNi_{x}V_{1-x}O_{3} thin films

The room temperature (300 K) electronic structure of pulsed laser deposited LaNi_{x}V_{1-x}O_{3} thin films have been demonstrated. The substitution of early-transition metal (TM) V in LaVO_{3} thin films with late-TM Ni leads to the decreasing in out-of-plane lattice parameter. Doping of Ni does not alter the formal valence state of Ni and V in LaNi_{x}V_{1-x}O_{3} thin films, divulging the absence of carrier doping into the system. The valence band spectrum is observed to comprise of incoherent structure owing to the localized V 3d band along with the coherent structure at Fermi level. With increase in Ni concentration, the weight of the coherent feature increases, which divulges its origin to the Ni 3d-O 2p hybridized band. The shift of Ni 3d-O 2p hybridized band towards higher energy in Ni doped LaVO_{3} films compared to the LaNiO_{3} film endorses the modification in ligand to metal charge transfer (CT) energy. The Ni doping in Mott-Hubbard insulator LaVO_{3} leads to the closure of Mott-Hubbard gap by building of spectral weight that provides the delocalized electrons for conduction. A transition from bandwidth control Mott-Hubbard insulator LaVO_{3} to negative CT metallicity character in LaNiO_{3} film is observed. The study reveals that unlike in Mott-Hubbard insulators where the strong Coulomb interaction between the 3d electrons decides the electronic structure of the system, CT energy can deliver an additional degree of freedom to optimize material properties in Ni doped LaVO_{3} films.Comment: 30 pages, 8 figure

Computational analysis and predictive modeling of polymorph descriptors

Abstract Background A computation approach based on integrating high throughput binding affinity comparison and binding descriptor classifications was utilized to establish the correlation among substrate properties and their affinity to Breast Cancer Resistant Protein (BCRP). The uptake rates of Mitoxantrone in the presence of various substrates were evaluated as an in vitro screening index for comparison of their binding affinity to BCRP. The effects of chemical properties of various chemotherapeutics, such as antiviral, antibiotic, calcium channel blockers, anticancer and antifungal agents, on their affinity to BCRP, were evaluated using HEK (human embryonic kidney) cells in which 3 polymorphs, namely 482R (wild type) and two mutants (482G and 482T) of BCRP, have been identified. The quantitative structure activity relationship (QSAR) model was developed using the sequential approaches of Austin Model 1 (AM1), CODESSA program, heuristic method (HM) and multiple linear regression (MLR) to establish the relationship between structural specificity of BCRP substrates and their uptake rates by BCRP polymorphs. Results The BCRP mutations may induce conformational changes as manifested by the altered uptake rates of Mitoxantrone by BCRP in the presence of other competitive binding substrates that have a varying degree of affinities toward BCRP efflux. This study also revealed that the binding affinity of test substrates to each polymorph was affected by varying descriptors, such as constitutional, topological, geometrical, electrostatic, thermodynamic, and quantum chemical descriptors. Conclusion Descriptors involved with the net surface charge and energy level of substrates seem to be the common integral factors for defining binding specificity of selected substrates to BCRP polymorph. The reproducible outcomes and validation process further supported the accuracy of the computational model in assessing the correlation among descriptors involved with substrate affinity to BCRP polymorph. A quantitative computation approach will provide important structural insight into optimal designing of new chemotherapeutic agents with improved pharmacological efficacies.Peer Reviewe

Molecular enneanuclear CuII phosphates containing planar hexanuclear and trinuclear sub-units: syntheses, structures, and magnetism

Highly symmetric enneanuclear copper(II) phosphates [Cu9(Pz)6(μ-OH)3(μ3-OH)(ArOPO3)4(DMF)3] (PzH =pyrazole, Ar = 2,6-(CHPh2)2-4-R-C6H2; R = Me, 2MeAr; Et, 2EtAr; iPr, 2iPrAr; and Ar = 2,6-iPr2C6H3, 2Dip) comprising nine copper(II) centers and pyrazole, hydroxide and DMF as ancillary ligands were synthesized by a reaction involving the arylphosphate monoester, 1, copper(I)chloride, pyrazole, and triethylamine in a 4 : 9 : 6 : 14 ratio. All four complexes were characterized by single crystal structural analysis. The complexes contain two distinct structural motifs within the multinuclear copper scaffold: a hexanuclear unit and a trinuclear unit. In the latter, the three Cu(II) centres are bridged by a µ3-OH. Each pair of Cu(II) centers in the trinuclear unit are bridged by a pyrazole ligand. The hexanuclear unit is made up of three dinuclear Cu(II) motifs where the two Cu(II) centres are bridged by an -OH and a pyrazole ligand. The three dinuclear units are connected to each other by phosphate ligands. The latter also aid the fusion of the trinuclear and the hexanuclear motifs. Magnetic studies reveal a strong antiferromagnetic exchange between the Cu(II) centres of the dinuclear units in the hexanuclear part and a strong spin frustration in the trinuclear part leading to a degenerate ground state

Production of He-4 and (4) in Pb-Pb collisions at root(NN)-N-S=2.76 TeV at the LHC

Results on the production of He-4 and (4) nuclei in Pb-Pb collisions at root(NN)-N-S = 2.76 TeV in the rapidity range vertical bar y vertical bar <1, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0-10% central events are found to be dN/dy4(He) = (0.8 +/- 0.4 (stat) +/- 0.3 (syst)) x 10(-6) and dN/dy4 = (1.1 +/- 0.4 (stat) +/- 0.2 (syst)) x 10(-6), respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature (T-chem = 156 MeV) as for light hadrons. The measured ratio of (4)/He-4 is 1.4 +/- 0.8 (stat) +/- 0.5 (syst). (C) 2018 Published by Elsevier B.V.Peer reviewe

Enhanced Thermoelectric Performance in the SrTi_0.85Nb_0.15O₃ Oxide Nanocomposite with Fe₂O₃‑Functionalized Graphene

Doped SrTiO3 is considered one of the potential thermoelectric (TE) candidates but its TE figure of merit, ZT needs to be improved for practical application of electricity generation from high-grade waste-heat. In the present work, enhanced TE performance has been realized for SrTi0.85Nb0.15O3 (STN) perovskite adopting the strategy of composite formation with Fe2O3-functionalized graphene (FGR). We have achieved a maximum electrical conductivity of 1.4 × 105 S m–1 for 1 wt % FGR added to STN, which is around 1185% larger than that of pristine STN. The presence of FGR in the STN matrix acts as a mobility booster of electrons, overcoming the effect of Anderson localization of electrons, which impedes the electron transport in STN. This is evident from the order of magnitude increase in weighted mobility of STN after FGR addition. Furthermore, the incorporation of FGR causes about a 34% decrease in the lattice thermal conductivity. The Debye–Callaway model demonstrates that the phonon–phonon Umklapp scattering is primarily responsible for reduced thermal conductivity. The presence of FGR sheets along the grain boundaries of STN, Fe2O3 nanoparticles, and lattice imperfections gives rise to the glass-like temperature-independent phonon mean-free-path, especially above Debye temperature. The maximum ZT ∼ 0.57 has been obtained at 947 K for the 1 wt % FGR sample, which is around 420% higher than that of pristine STN. Furthermore, we have fabricated a prototype of a four-legged n-type TE module, demonstrating one of the highest power outputs of 18 mW among reported oxide thermoelectrics