Thermal conductivity and diffusion-mediated localization in Fe_{1-x}Cr_{x} Alloys

We apply a new Kubo-Greenwood type formula combined with a generalized Feynman diagram- matic technique to report a first principles calculation of the thermal transport properties of disordered Fe_{1-x}Cr_{x} alloys. The diagrammatic approach simplifies the inclusion of disorder-induced scattering effects on the two particle correlation functions and hence renormalizes the heat current operator to calculate configuration averaged lattice thermal conductivity and diffusivity. The thermal conductivity K(T) in the present case shows an approximate quadratic T-dependence in the low temperature regime (T < 20 K), which subsequently rises smoothly to a T-independent saturated value at high T . A numerical estimate of mobility edge from the thermal diffusivity data yields the fraction of localized states. It is concluded that the complex disorder scattering processes, in force-constant dominated disorder alloys such as Fe-Cr, tend to localize the vibrational modes quite significantly.Comment: 5 pages, 5 figure

d0 Ferromagnetism in Li-doped ZnO Compounds

Recently, d0 ferromagnetic materials have been projected as one of the promising novel materials for spintronics applications. In this work, we have studied Li-doped ZnO compounds, i.e. Zn1-xLixO (x=0, 0.02, 0.04, and 0.06) samples, prepared by the solid-state reaction route method. From the study of crystal structure using X-ray diffraction (XRD) patterns, it is evident that the prepared materials have been formed in a single-phase of the hexagonal wurtzite structure. The refinement of the XRD patterns suggests that there are very small changes in the lattice parameters upon Li-incorporation in ZnO. The average crystallite size (SC), estimated from XRD patterns was found to be in the range of 35-50 nm. The microstructural study by scanning electron microscope reveals the uniform morphology of the grains of the order of 50-70 nm. The energy dispersive spectrum indicates that no unwanted ferromagnetic impurities have crept into the final prepared samples. The measurement of the temperature (T) variation of magnetization (M) with SQUID magnetometer indicates that undoped ZnO exhibits diamagnetic property but all Li-doped compounds exhibit room-temperature ferromagnetism and with a magnetic irreversibility behavior between zero-field cooled and field cooled M-T data. From the magnetization versus field measurements at 3 and 300 K, it is observed that Li-doped samples exhibit ferromagnetic loops with ultra-soft coercivity (~50 Oe) and with a maximum saturation magnetization of 0.10 emu/gm for x= 0.02 sample, which decreases with the increase in Li concentration.Comment: 16 page

Structural, Electronic, Thermal, Mechanical and Elastic Properties of Rpd3 (R = La & Y) Compounds Based on Ab-initio Calculation

The structural, electronic, thermal, mechanical and elastic properties of cubic non magnetic RPd3 (R = La &amp;Y) compounds which crystallize in the AuCu3 structure have been studied using ab-initio full potential linearized augmented plane wave (FP-LAPW) method within density functional theory (DFT) using generalized gradient approximation (GGA) for exchange correlation potential. The ground states properties such as lattice parameter (a), bulk modulus (B) and pressure derivative (B') have been obtained using optimization method. The elastic properties such as Young’s modulus (E), Poisson’s ratio (?) and anisotropic ratio (A) and thermal are predicted for first time. The ductility of these compounds has been analyzed using Pugh criteria. Keywords: Ab-initio; Density functional theory; Elastic constants; Ductility. 

Visual, Optical and Replica Inspections: Surface Preparation of 650 MHz NB Cavity for PIP-II Linac

Surface preparation of niobium superconducting RF cavities is a critical step for achieving good RF performance under the superconducting state. Surface defect, roughness, and contamination affect the accelerating gradient and quality factor of the cavities. We report surface inspection methods used to control the surface processing of 650 MHz cavities designated for the pre-production and prototype cryomodules for PIP-II linac. The cavity surface was routinely inspected visually, with an optical camera, and by microscopic scanning of surface replicas. This article covers details on the surface inspection methods and surface polishing process used to repair the surface

Isolation, identification and bioactive potential of bacterial endophytes from Coleus

Coleus (Lamiaceae) is a large and widespread genus comprising of species with diverse ethnobotanical uses. In the present study, bacterial endophytes were isolated from Coleus forskohlii and Coleus aromaticus. Endophytes are the microorganisms which reside within the plants without showing any harmful effect on its host. Diverse types of endophytes live symbiotically within almost all plants and in turn help the plant in a number of ways such as imparting resistance against biotic and abiotic stresses, producing compounds involved in attraction of pollinators, inducing the plant defense mechanisms, etc. The bacterial endophytes isolated in this study, were characterized by microscopic examination (using gram staining) and molecularly identified by sequencing the 16S rRNA. Extracts were prepared from endophytic biomass using solvents of different polarities (methanol, ethyl acetate and butanol) and were screened for their bioactive potential (in vitro cytotoxicity anti-microbial, and anti-oxidant activity). Scale-up of endophytes showing promising results is under process, which will help in isolation of pure compounds

DIET : new developments and recent results

Among existing grid middleware approaches, one simple, powerful, and flexibleapproach consists of using servers available in different administrative domainsthrough the classic client-server or Remote Procedure Call (RPC) paradigm.Network Enabled Servers (NES) implement this model also called GridRPC.Clients submit computation requests to a scheduler whose goal is to find aserver available on the grid. The aim of this paper is to give an overview of anNES middleware developed in the GRAAL team called DIET and to describerecent developments. DIET (Distributed Interactive Engineering Toolbox) is ahierarchical set of components used for the development of applications basedon computational servers on the grid.Parmi les intergiciels de grilles existants, une approche simple, flexible et performante consiste a utiliser des serveurs disponibles dans des domaines administratifs différents à travers le paradigme classique de l’appel de procédure àdistance (RPC). Les environnements de ce type, connus sous le terme de Network Enabled Servers, implémentent ce modèle appelé GridRPC. Des clientssoumettent des requêtes de calcul à un ordonnanceur dont le but consiste àtrouver un serveur disponible sur la grille.Le but de cet article est de donner un tour d’horizon d’un intergiciel développédans le projet GRAAL appelé DIET 1. DIET (Distributed Interactive Engineering Toolbox) est un ensemble hiérarchique de composants utilisés pour ledéveloppement d’applications basées sur des serveurs de calcul sur la grille