Determination of the Indigenous Microflora of Men in Controlled Environments Final Report, Jul. 1964 - Nov. 1965

Determination of indigenous microflora in man during simulated space travel for establishing personal hygiene and sanitation criteri

Reflection high-energy electron diffraction patterns of CrSi_2 films on (111) silicon

Highly oriented films of the semiconducting transition metal silicide, CrSi2, were grown on (111) silicon substrates, with the matching crystallographic faces being CrSi_2(001)/Si(111). Reflection high‐energy electron diffraction (RHEED) yielded symmetric patterns of sharp streaks. The expected streak spacings for different incident RHEED beam directions were calculated from the reciprocal net of the CrSi_2(001) face and shown to match the observed spacings. The predominant azimuthal orientation of the films was thus determined to be CrSi_2〈210〉∥Si〈110〉. This highly desirable heteroepitaxial relationship may be described with a common unit mesh of 51 Å^2 and a mismatch of −0.3%. RHEED also revealed the presence of limited film regions of a competing azimuthal orientation, CrSi_2〈110〉∥Si〈110〉. A new common unit mesh for this competing orientation is suggested; it possesses an area of 612 Å^2 and a mismatch of −1.2%

Channeling of MeV ions in polyatomic epitaxial films: ReSi2 on Si(100)

Channeling of a He beam in the energy range from 1.4 to 2.7 MeV in a polyatomic epitaxial ReSi2 film (∼150 nm thick) was studied by detecting backscattered He ions. The critical angles and the minimum yields of both the heavy (Re) and the light (Si) elements are obtained directly from backscattering measurements. The critical angles of both Re and Si scale as √1/E. The critical angle of Re is always about 2.3 times that of Si. The minimum yields of both Re and Si do not change over this energy range. The minimum yield of Re (2%) is about 1/7 that of Si (14%). The results are explained qualitatively and quantitatively by the continuum model suitably extended for polyatomic crystals. An important corollary is that a high value for the minimum yield of the light element in a polyatomic single crystal does not necessarily mean that the sublattice of the light element is disordered

Functional genomics and microbiome profiling of the Asian longhorned beetle (\u3ci\u3eAnoplophora glabripennis\u3c/i\u3e) reveal insights into the digestive physiology and nutritional ecology of wood feeding beetles

Background: Wood-feeding beetles harbor an ecologically rich and taxonomically diverse assemblage of gut microbes that appear to promote survival in woody tissue, which is devoid of nitrogen and essential nutrients. Nevertheless, the contributions of these apparent symbionts to digestive physiology and nutritional ecology remain uncharacterized in most beetle lineages. Results: Through parallel transcriptome profiling of beetle- and microbial- derived mRNAs, we demonstrate that the midgut microbiome of the Asian longhorned beetle (Anoplophora glabripennis), a member of the beetle family Cerambycidae, is enriched in biosynthetic pathways for the synthesis of essential amino acids, vitamins, and sterols. Consequently, the midgut microbiome of A. glabripennis can provide essential nutrients that the beetle cannot obtain from its woody diet or synthesize itself. The beetle gut microbiota also produce their own suite of transcripts that can enhance lignin degradation, degrade hemicellulose, and ferment xylose and wood sugars. An abundance of cellulases from several glycoside hydrolase families are expressed endogenously by A. glabripennis, as well as transcripts that allow the beetle to convert microbe-synthesized essential amino acids into non-essential amino acids. A. glabripennis and its gut microbes likely collaborate to digest carbohydrates and convert released sugars and amino acid intermediates into essential nutrients otherwise lacking from their woody host plants. Conclusions: The nutritional provisioning capabilities of the A. glabripennis gut microbiome may contribute to the beetles’ unusually broad host range. The presence of some of the same microbes in the guts of other Cerambycidae and other wood-feeding beetles suggests that partnerships with microbes may be a facilitator of evolutionary radiations in beetles, as in certain other groups of insects, allowing access to novel food sources through enhanced nutritional provisioning

Self-pulsing oxide-confined vertical-cavity lasers with ultralow operating current

Includes bibliographical references (page 460).Selectively oxidised vertical-cavity lasers which exhibit self-pulsatin glasing at currents as low as 470nA are reported. Characteristics including linearly polarised emission, narrow linewidths and coherent near- and far-field diffraction indicate that these devices operate as lasers at DC currents 1mA

Fates of imine intermediates in radical cyclizations of N-sulfonylindoles and ene-sulfonamides

Abstract Two new fates of imine intermediates formed on radical cyclizations of ene-sulfonamides have been identified, reduction and hydration/fragmentation. Tin hydride-mediated cyclizations of 2-halo-N-(3-methyl-N-sulfonylindole)anilines provide spiro[indoline-3,3'-indolones] or spiro-3,3'-biindolines (derived from imine reduction), depending on the indole C2 substituent. Cyclizations of 2-haloanilide derivatives of 3-carboxy-N-sulfonyl-2,3-dihydropyrroles also presumably form spiro-imines as primary products. However, the lactam carbonyl group facilitates the ring-opening of these cyclic imines by a new pathway of hydration and retroClaisen-type reaction, providing rearranged 2-(2'-formamidoethyl)oxindoles. 164

Uniformity and performance of selectively oxidized VCSEL arrays

The authors report the uniformity characteristics of low threshold 1,060 nm and high power 850 nm 8 x 8 individually addressable oxide-confined VCSEL arrays. Uniformity of lasing thresholds and operating characteristics are described, as well as thermal issues for 2-dimensional laser arrays

Fabrication issues of oxide-confined VCSELs

To insert high-performance oxide-confined vertical-cavity surface- emitting lasers (VCSELs) into the manufacturing arena, we have examined the critical parameters that must be controlled to establish a repeatable and uniform wet thermal oxidation process for AlGaAs. These parameters include the AlAs mole fraction, sample temperature, carrier gas flow, and bubbler water temperature. Knowledge of these parameters has enable the compilation of oxidation rate data for AlGaAs which exhibits an Arrhenius rate dependence. The compositionally dependent activation energies for Al{sub x}Ga{sub 1-x}As layers of x=1.00, 0.98, and 0.92 are found to be 1.24, 1.75, and 1.88 eV, respectively. 7 figs, 1 tab, 14 refs

Radiation damage in ReSi2 by a MeV 4He beam

Epitaxial ReSi2 thin films grown on Si (100) substrates were analyzed at room temperature by MeV 4He backscattering and channeling spectrometry. The minimum yield of [100] axial channeling increases with increasing exposure of the ReSi2 sample to the analyzing He beam. This means that ReSi2 suffers irradiation damage induced by a MeV 4He beam. The damage in the film induced by a beam incident along a random direction is about one order of magnitude larger than that induced by a beam with an aligned incidence, indicating that the damage is mainly generated by elastic collisions of nuclei. The experimentally measured defect concentration produced at 300 K by a beam of random incidence is compared with the theoretically estimated one produced at 0 K in an amorphous target. The agreement is fairly good, suggesting that the defects are stable at room temperature