Tunneling spectroscopy of the superconducting state of URu2Si2

We present measurements of the superconducting gap of URu$_2$Si$_2$ made with scanning tunneling microscopy (STM) using a superconducting tip of Al. We find tunneling conductance curves with a finite value at the Fermi level. The density of states is V shaped at low energies, and the quasiparticle peaks are located at values close to the expected superconducting gap from weak coupling BCS theory. Our results point to rather opened gap structures and gap nodes on the Fermi surface

Dose Modeling Evaluations and Technical Support Document For the Authorized Limits Request for the DOE-Owned Property Outside the Limited Area, Paducah Gaseous Diffusion Plant Paducah, Kentucky

Environmental assessments and remediation activities are being conducted by the U.S. Department of Energy (DOE) at the Paducah Gaseous Diffusion Plant (PGDP), Paducah, Kentucky. The Oak Ridge Institute for Science and Education (ORISE), a DOE prime contractor, was contracted by the DOE Portsmouth/Paducah Project Office (DOE-PPPO) to conduct radiation dose modeling analyses and derive single radionuclide soil guidelines (soil guidelines) in support of the derivation of Authorized Limits (ALs) for 'DOE-Owned Property Outside the Limited Area' ('Property') at the PGDP. The ORISE evaluation specifically included the area identified by DOE restricted area postings (public use access restrictions) and areas licensed by DOE to the West Kentucky Wildlife Management Area (WKWMA). The licensed areas are available without restriction to the general public for a variety of (primarily) recreational uses. Relevant receptors impacting current and reasonably anticipated future use activities were evaluated. In support of soil guideline derivation, a Conceptual Site Model (CSM) was developed. The CSM listed radiation and contamination sources, release mechanisms, transport media, representative exposure pathways from residual radioactivity, and a total of three receptors (under present and future use scenarios). Plausible receptors included a Resident Farmer, Recreational User, and Wildlife Worker. single radionuclide soil guidelines (outputs specified by the software modeling code) were generated for three receptors and thirteen targeted radionuclides. These soil guidelines were based on satisfying the project dose constraints. For comparison, soil guidelines applicable to the basic radiation public dose limit of 100 mrem/yr were generated. Single radionuclide soil guidelines from the most limiting (restrictive) receptor based on a target dose constraint of 25 mrem/yr were then rounded and identified as the derived soil guidelines. An additional evaluation using the derived soil guidelines as inputs into the code was also performed to determine the maximum (peak) dose for all receptors. This report contains the technical basis in support of the DOE?s derivation of ALs for the 'Property.' A complete description of the methodology, including an assessment of the input parameters, model inputs, and results is provided in this report. This report also provides initial recommendations on applying the derived soil guidelines

A Review On Geotrichum Lipases: Production, Purification, Immobilization And Applications

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Lipases are enzymes produced from innumerous microorganisms, plants and animal cells. They catalyze reactions of different lipid sources. The Geotrichum fungi are good producers of lipases with high hydrolytic activity and specificity for unsaturated fatty acids. A great number of studies have reported the importance of lipase from this genus and described important fermentation parameters for the enzyme production, such as nutrients, temperature, pH, inoculum, time of fermentation and others. Furthermore, different strategies have been used to purify and immobilize lipases from Geotrichum and innumerous applications are cited in different processes as polyunsaturated fatty acids enrichment, hydrolysis and esterification of fat and oils, synthesis of aromas, biodiesel, and many others. This review highlights fundamental aspects of the production, purification, characterization, immobilization, and the applications of lipases produced by the genus Geotrichum.304439454Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP, Brazil)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq, Brazil)Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES, Brazil)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Strain balanced quantum posts

Quantum posts are assembled by epitaxial growth of closely spaced quantum dot layers, modulating the composition of a semiconductor alloy, typically InGaAs. In contrast with most self-assembled nanostructures, the height of quantum posts can be controlled with nanometer precision, up to a maximum value limited by the accumulated stress due to the lattice mismatch. Here we present a strain compensation technique based on the controlled incorporation of phosphorous, which substantially increases the maximum attainable quantum post height. The luminescence from the resulting nanostructures presents giant linear polarization anisotropy.Comment: Submitted to Applied Physics Letters (7th March 2011). 4 pages, 4 figure

Surface Morphology and Electrical Resistivity in Polycrystalline Au/Cu/Si(100) System

This work describes the analysis of morphology and electrical resistivity (ρ) obtained in the Au/Cu/Si system. The Au/Cu bilayers were deposited by thermal evaporation technique with thicknesses from 50 to 250 nm on SiOx/Si(100) substrates. The Au : Cu concentration ratio of the samples was of 25 : 75 at%. The bilayers were annealed into a vacuum oven with argon atmosphere at 660 K for one hour. The crystalline structures of AuCu and CuSi alloys were confirmed by X-ray diffraction analysis. The scanning electron microscopy (SEM), the atomic force microscopy (AFM), and the energy dispersive spectroscopy (EDS) were used to study the morphology, final thickness, and the atomic concentration of the alloys formed, respectively. The four-point probe technique was used to measure the electrical resistivity (ρ) in the prepared alloys as a function of thickness. The ρ value was measured and it was numerically compared with the Fuchs–Sondheimer (FS) and the Mayadas–Shatzkes (MS) models of resistivity. Results show values of electrical resistivity between 0.9 and 1.9 μΩ-cm. These values are four times smaller than the values of the AuCu systems reported in literature

Atomically resolved chemical ordering at the nm-thick TiO precipitate/matrix interface in V-4Ti-4Cr alloy

We have used advanced analytical electron microscopy to characterise the local structure and chemistry at the interface between nm-thick TiO precipitates and the V-based matrix in a V-4Ti-4Cr alloy. Our results reveal the presence of an intergrowth between the fcc TiO and bcc vanadium structures, with a repeat lattice distance that equals 2.5 times the vanadium lattice parameter along the c-axis. Our atomic resolution analysis of the interface will impact the mechanistic understanding of its interaction with interstitials and radiation-induced lattice defects, and consequently trigger the development of improved alloy structures with interfaces engineered for enhanced radiation tolerance

A Review on Geotrichum Lipases: Production, Purification, Immobilization and Applications

Lipases are enzymes produced from innumerous microorganisms, plants and animal cells. They catalyze reactions of different lipid sources. The Geotrichum fungi are good producers of lipases with high hydrolytic activity and specificity for unsaturated fatty acids. A great number of studies have reported the importance of lipase from this genus and described important fermentation parameters for the enzyme production, such as nutrients, temperature, pH, inoculum, time of fermentation and others. Furthermore, different strategies have been used to purify and immobilize lipases from Geotrichum and innumerous applications are cited in different processes as polyunsaturated fatty acids enrichment, hydrolysis and esterification of fat and oils, synthesis of aromas, biodiesel, and many others. This review highlights fundamental aspects of the production, purification, characterization, immobilization, and the applications of lipases produced by the genus Geotrichum

Analysis of an Energetic Electron Injection at GEO Using FalconSEED: A Low SWaP-C, CubeSat-Compatible Instrument for Space Environments

We present a detailed analysis of an energetic electron injection (10s - 100s keV) observed at geostationary Earth orbit (GEO) on March 5, 2022 in order to highlight the capabilities of the Falcon Solid-state Energetic Electron Detector (SEED). The high time- and energy-resolution of SEED are used to quantify the dispersion of the injection front and to explore the morphology of the energy distribution throughout the injection encounter. Observations of the same event from nearby platforms are included for context. The SEED is a CubeSat compatible, single element particle telescope, designed to measure 14 to 145keV electrons in GEO. The flight payload has a volume of 10 cm x 10 cm x 20 cm, in a 4.3-kg, 3.4-W package. The SEED was manifested on the Department of Defense (DoD) Space Test Program Satellite—6 (STPSat-6) which was launched in December of 2021 to GEO at 112 W longitude. During the first year of mission operations, the SEED has demonstrated the ability, evidenced in this paper, or a low-resource particle detector comprised of predominantly commercial-off-the-shelf components to provide relevant science observations of the space plasma environment