Thermodynamic properties of ZnO with in mie-gruneisen hypothesis

Zink oxide (mineral name: Zincite) is an attractive wide band gap semiconductor due to its large number of industrial applications such as in the production of solar cells, liquid-crystal displays, electrochromic devices, LED, as well as adhesive taps, automobile tires, ceramics, glass, varistors, etc. It is due to versatile nature of ZnO, in we have studied its thermal properties at high temperatures. Theoretically, complete ab initio investigations at elevated temperatures are restricted due largely to computational complexity of many-body nature. We have therefore used an consistent iterative scheme to include thermal effect by combining the universal equation of state (UEOS) to the Mie-Gruneisen hypothesis. It is demonstrated that from the knowledge of cohesive properties at ambient condition various thermodynamic properties can be predicted at finite temperatures and pressures. For example, presently calculated relative volume-thermal expansions, static EOS are in good accordance with experimental results. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2787

Electrical Transport in Polyvalent Liquid Bismuth and Antimony Metals

Accurate assessment of electrical transport for heavy polyvalent metals pause challenge due to complex electronic band structure, where s-wave scattering theory due to Ziman is failed. Improving schemes like t-matrix resistivity and self-consistent approach are proposed. In the present study, we employ selfconsistent approach to compute electrical resistivity (ρ) in liquid Bi and Sb at different temperatures (T). Structural input is estimated through charged hard-sphere reference system. Electron-ion interaction is modelled by modified empty-core pseudopotential including electron exchange and correlation effects. Since only two parameters are independent, as the core radius RC (= 0.51 RaZ − 1⁄3) is a theoretical input, we have tuned, once and for all, the single parameter to find ρ at melting temperature. The same set of parameters is used to deduce high-T resistivity, thermal conductivity and thermo-electric power. Overall good agreement is observed for transport properties for both metals. The present fitting scheme and so deduced results are discussed in comparison with other findings

The Theoretical Study of Electron Dispersion of Some Liquid Metals Using Transition Metal Model Potential (TMMP)

In the present communication, we have proposed a simple method using which two parameters of Kumar’s pseudopotential can be reduced to effectively single parameter. Further the reliability of our proposed method is examined by carrying out electron dispersion curves (E(k) → k), Fermi energy (EF) and density of states at Fermi energy (N(EF)) for sixteen liquid metals. In absence of any experimental or theoretical results of aforesaid properties, our results will throw some light in the determination of interactions persisting in the liquid state of transition metals

Quasiharmonic r–space Computational Scheme for Phonon Dynamics: Case Study of Calcium Oxide

The role of phonons is important in accounting various properties of materials. Crystal potential being an anharmonic function of volume, variations are seen in phonon derived properties with a change in volume. In the present work, we employ an approximate technique of expanding phonon frequencies using Taylor series expansion upto second-order in volume to calculate the volume dependent phonon frequencies of CaO in B1 and B2 phases. Equilibrium properties are obtained by fitting Murnaghan EoS to first principles DFT based results, however. The mode Grüneisen parameter and concavity parameter are computed with the help of present ab initio phonon frequencies for both the phases. Their volume dependence are estimated analytically using the proposed scheme. We find that phonon frequencies increase by decreasing volume. Analytically calculated volume dependent phonon frequencies are compared in reasonable agreement with the frequencies obtained directly using DFT for B1-phase. Thus, the present r–space computational scheme of deriving volume dependent phonon frequency proves to be an alternative to overcome lengthy phonon calculations

Temperature Variation of Debye-Waller Factor and Mean Square Displacement for bcc Metals Using Density Based Pseudopotential

The variation of Debye-Waller factors and mean square displacements at different temperatures for simple bcc metals Li, Na, Rb and Cs is studied using pseudopotential proposed by Fiolhais et al. Comparison of computed theoretical values with experimental results is made and discussed. A reasonable agreement is found between our results and experimental data

The Study of Lattice Dynamics and Dynamical Elastic Constants for Calcium (Ca) and Strontium (Sr) in bcc Phase Using Pseudopotential Approach

Pseudopotential methods have been used successfully to understand static, dynamical and transport properties with good degree of agreement in condensed matter physics. In the present communication, we have investigated lattice dynamics of Ca and Sr in bcc phase using local pseudopotential due to George et al. The pseudopotential contains two parameters rc and which are determined from zero pressure condition. The computed results of phonon frequencies are in good agreement with experimental finding and maximum deviation for both the metals are about 10 % with experimental findings. Further, we have computed dynamical elastic constants (C11, C12 and C44) and bulk moduli (B) which are also comparable with experimental results and other theoretical results. Success of present study reveals that both metals behave as a simple metal rather than early transition metals and extra term for the inclusion of s-d hybridization is not required

Theoretical Investigations of Lattice Dynamics and Dynamical Elastic Constants of Rh0.6Pd0.4 and Rh0.2Pd0.8 Binary Alloys Using Transition Metal Pseudopotential

The experimental and theoretical studies of various properties of transition metals alloys are important in the material science research. Inspired by such fact, in the present communication we have carried out theoretical studies of lattice dynamics and dynamical elastic constants of Rh0.6Pd0.4 and Rh0.2Pd0.8 using transition metal pseudopotential. The form of the pseudopotential used in the present calculation is directly derived from generalized pseudopotential theory (GPT) and no phenomenology was used to construct pseudopotential in real space. The pseudopotential was found to be successful for the study of static, dynamic and transport properties of many transition metals. In absence of any experimental and theoretical studies first time we are presenting theoretical results of phonon dispersion for both the alloys which may be considered as prediction. Due to unavailability of experimental results, presently computed elastic constants are comparable with those studied recently by using Exact Muffin-Tin Orbitals method within the Perdew-Burke-Ernzerhof exchange-correlation approximation. Encouraged by present approach, we would like to extend it further for the remaining binary alloys of transition metals alloys

The Comparative Study of Electrical Resistivity of bcc Liquid Transition Metals

In the present paper, we have used Ziman’s approach and transition matrix (t-matrix) approach to study the electrical resistivities of bcc liquid metals. By carrying out this study, we have verified the validity of our proposed pseudopotential extracted from generalized pseudopotential theory (GPT). Our theoretical results agree well with experimental results. Also, it has been verified that for transition metals tmatrix approach is more realistic and physically sound than Ziman approach

Metagenomics combined with activity-based proteomics point to gut bacterial enzymes that reactivate mycophenolate

Mycophenolate mofetil (MMF) is an important immunosuppressant prodrug prescribed to prevent organ transplant rejection and to treat autoimmune diseases. MMF usage, however, is limited by severe gastrointestinal toxicity that is observed in approximately 45% of MMF recipients. The active form of the drug, mycophenolic acid (MPA), undergoes extensive enterohepatic recirculation by bacterial beta-glucuronidase (GUS) enzymes, which reactivate MPA from mycophenolate glucuronide (MPAG) within the gastrointestinal tract. GUS enzymes demonstrate distinct substrate preferences based on their structural features, and gut microbial GUS enzymes that reactivate MPA have not been identified. Here, we compare the fecal microbiomes of transplant recipients receiving MMF to healthy individuals using shotgun metagenomic sequencing. We find that neither microbial composition nor the presence of specific structural classes of GUS genes are sufficient to explain the differences in MPA reactivation measured between fecal samples from the two cohorts. We next employed a GUS-specific activity-based chemical probe and targeted metaproteomics to identify and quantify the GUS proteins present in the human fecal samples. The identification of specific GUS enzymes was improved by using the metagenomics data collected from the fecal samples. We found that the presence of GUS enzymes that bind the flavin mononucleotide (FMN) is significantly correlated with efficient MPA reactivation. Furthermore, structural analysis identified motifs unique to these FMN-binding GUS enzymes that provide molecular support for their ability to process this drug glucuronide. These results indicate that FMN-binding GUS enzymes may be responsible for reactivation of MPA and could be a driving force behind MPA-induced GI toxicity.Bio-organic Synthesi

ϒ production in p–Pb collisions at √sNN=8.16 TeV

ϒ production in p–Pb interactions is studied at the centre-of-mass energy per nucleon–nucleon collision √sNN = 8.16 TeV with the ALICE detector at the CERN LHC. The measurement is performed reconstructing bottomonium resonances via their dimuon decay channel, in the centre-of-mass rapidity intervals 2.03 < ycms < 3.53 and −4.46 < ycms < −2.96, down to zero transverse momentum. In this work, results on the ϒ(1S) production cross section as a function of rapidity and transverse momentum are presented. The corresponding nuclear modification factor shows a suppression of the ϒ(1S) yields with respect to pp collisions, both at forward and backward rapidity. This suppression is stronger in the low transverse momentum region and shows no significant dependence on the centrality of the interactions. Furthermore, the ϒ(2S) nuclear modification factor is evaluated, suggesting a suppression similar to that of the ϒ(1S). A first measurement of the ϒ(3S) has also been performed. Finally, results are compared with previous ALICE measurements in p–Pb collisions at √sNN = 5.02 TeV and with theoretical calculations.publishedVersio