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  • 1
    Electronic Resource
    Electronic Resource
    Effects of high temperature irradiation on SmCo permanent magnets (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 2075-2076 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: SmCo5 permanent magnets have been irradiated with 19.5 MeV protons at temperatures from about 300 to over 800 K. The results show that SmCo5 magnets are very sensitive to irradiation at elevated temperatures. The relative magnetic flux loss has been calculated with a model based on the local heating caused by the incoming particle. The theoretical result agrees well with the experimental data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351641
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  • 2
    Electronic Resource
    Electronic Resource
    Trapping of quasiparticles of a nonequilibrium superconductor (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 2782-2784 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have performed experiments where hot electrons are extracted from a normal metal into a superconductor through a tunnel junction. We have measured the cooling performance of such NIS junctions, especially in the cases where another normal metal electrode, a quasiparticle trap, is attached to the superconductor at different distances from the junction in direct metal–to–metal contact or through an oxide barrier. The direct contact at a submicron distance allows superior thermalization of the superconductor. We have analyzed theoretically the heat transport in this system. From both experiment and theory, it appears that NIS junctions can be used as refrigerators at low temperatures only with quasiparticle traps attached. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.126474
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  • 3
    Electronic Resource
    Electronic Resource
    Hückel model for metal clusters: Ground states and low energy isomers (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 3041-3048 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Hückel model with one s-electron per atom is used to study the geometries and electronic structures of clusters of 9 to 22 atoms. Two different optimization schemes for obtaining the ground states are used; (i) minimization of an approximate Hückel ground state energy starting from a random geometry and (ii) simulated annealing. Both methods give similar and new ground state geometries for clusters with 10 to 14 atoms. All clusters with more than 10 atoms will be distorted if the bond distance is allowed to vary ±5.5%. The ground states of clusters with atoms 10, 11, 12, and 14 are found to have the N=9 cluster as the basic building block, whereas the N=13 cluster is a distorted cuboctahedron. As a general trend, the deformation of clusters increases from atom number 8 to 14 and shrinks again from 15 to 20 atoms, in accordance with jellium model results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.467617
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  • 4
    Electronic Resource
    Electronic Resource
    Electronic degrees of freedom and unimolecular rate constants in metal clusters (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 10481-10484 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We calculate the modifications of the unimolecular rate constants for free metallic clusters due to thermally exited electronic degrees of freedom. The effect is essentially taken into account by substituting Helmholtz's free energy of the electronic system for the ground state energy. The activation energy pertaining to the electronic ground states of the mother and daughter cluster is then replaced by the first difference in Helmholtz's free energy. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.467866
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  • 5
    Electronic Resource
    Electronic Resource
    An ab initio study of cluster–surface interaction: Na clusters on the NaCl(001) surface (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 105 (1996), S. 10565-10571 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Structure, stability, dynamics, and the electronic structure of small sodium clusters with 2 to 12 atoms adsorbed on the NaCl(001) surface are studied using an ab initio total energy method. The interaction between the ideal surface and the metal cluster is found to be weak due to a large energy gap between the surface and the cluster single-electron states. As a result, the geometry and the electronic structure of the smallest clusters (N≤6) is distorted only slightly if compared to the free clusters. For larger sizes it seems possible to have both 2D and 3D structure isomers with a notable interisomeric energy barrier. The cluster binding energy to the surface has a local maximum at N=6 which we interpret to be caused by electronic shell effects in 2D. The weak cluster–surface interactions are modified dramatically in the presence of surface F centers (missing chlorine atoms). The F center increases the adsorption energy of sodium adatom by 1 eV and changes the nature of adsorption from physisorption to chemisorption. Similarly, the binding of small sodium clusters to the surface is enhanced by F centers. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.472769
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  • 6
    Electronic Resource
    Electronic Resource
    Fragmentation of small sodium clusters (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 4647-4653 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Fragmentation of small sodium clusters was studied by performing both ab initio and classical molecular dynamics simulations. In ab initio calculations at 1200–2400 K, neutral sodium clusters with 10 and 13 atoms ejected both monomers and dimers. The observed behavior is in agreement with previous calculations stating that the electronic shell oscillations diminish strongly as a function of temperature. The fragmentation rates obtained with the ab initio method are consistent with the Kelvin equation for the equilibrium vapor pressure of small clusters. The differences between the results obtained using different models reflect the differences between the dissociation energies calculated correspondingly. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1288380
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  • 7
    Electronic Resource
    Electronic Resource
    SPIRAL SYSTEM AND LASER COLONY SCANNER FOR ENUMERATION OF MICROORGANISMS (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food safety 11 (1990), S. 0 
    Details
    ISSN: 1745-4565
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Aerobic Plate Count (APC) and spiral plate (Spiral) methods using both manual counting (MC) and laser counting (LC) procedures were compared for pure bacterial, yeast, and mold cultures and raw milk samples. All four combinations of methods (APC-MC, APC-LC, Spiral-MC, and Spiral-LC) gave similar log10 counts of studied pure microbial cultures, producing results that were not different for the purposes of practical microbiology. With bacterial and yeast cultures, counts differed by less than half a logarithmic cycle (the range of difference = -0.26 to +0.42), the range of difference being -0.03 to +0.62 for Aspergillus flavus and Penicillium camemberti molds. An exception was noticed with Rhizopus oligosporus mold when plates were read by laser due to large (10–15 mm) colony size. The difference between the readings made manually and by laser colony scanner was about one logarithmic cycle with both APC and Spiral methods. Statistical analyses of the manually read results of bacterial and Saccharomyces cerevisiae spiral plates showed no differences at the 0.05 level of significance between the readings made by four or five persons. For raw milk samples, Spiral-MC and Spiral-LC methods gave higher microbial numbers than APC-MC (63% of samples) and APC-LC (54% of samples) at 0.05 level of significance (p〈0.001). Of the LC results, 75% were within a ± 0.5 logarithmic cycle range when compared to MC results, of which 98% were within the same range. All results were still within a ± 1.0 logarithmic range. When APC and Spiral for raw milk samples were analyzed, LC gave higher microbial numbers compared to MC: 71% of the APC-LC results were higher than APC-MC results, and 85% of Spiral-LC results were higher than Spiral-MC results at 0.05 level of significance (p〈0.001). 77% of the results by either plating technique were within a ± 0.5 logarithmic range.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-4565.1990.tb00049.x
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  • 8
    Electronic Resource
    Electronic Resource
    Phase diagram of argon clusters (1998)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 108 (1998), S. 5826-5833 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Systems containing both argon cluster with number of atoms N=100, 200, or 400 and argon vapor were studied with constant energy molecular dynamics simulations. The vapor pressure versus temperature phase diagram including the melting temperatures was determined as a function of cluster particle number. The melting temperature of the cluster was determined with a new method based on the nearest-neighbor exchange of atoms, and it was found to approach the bulk melting temperature linearly as a function of N−1/3. The vapor pressure versus temperature curve approached the corresponding bulk curve as the particle number of the cluster increased. At temperatures lower than the melting temperatures the clusters were found to contain an icosahedral core. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.475993
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  • 9
    Electronic Resource
    Electronic Resource
    Melting and evaporation of argon clusters (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 106 (1997), S. 1888-1892 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Molecular dynamics simulation with a Nosé–Hoover thermostat was used to study melting and evaporation of free icosahedral argon clusters containing 13 to 1415 atoms. Clusters of 147 atoms or less were found to melt at temperatures clearly below the bulk melting temperature in agreement with previous results. Clusters containing 309 atoms or more were observed to desorb atoms at temperatures where the core of the cluster is solid. As a consequence of this a reliable determination of their melting temperatures using molecular dynamics was found to be complicated. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.473327
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  • 10
    Electronic Resource
    Electronic Resource
    Application of rapid methods and ultrasound imaging in the assessment of the microbiological quality of aseptically packed starch soup (1991)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of food science & technology 26 (1991), S. 0 
    Details
    ISSN: 1365-2621
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The application of rapid microbiological methods such as automated turbidometry and microcolony count using the direct epifluorescence technique (DEFT) was tested for the quality control of aseptically packed ultra-high temperature-treated starch-based soup. In addition, a non-destructive method using ultrasound imaging through the packages prior to the microbiological analysis was evaluated. The results showed that ultrasound could be a promising non-destructive testing method in quality control schemes for starch-based foods. Certain problems associated with calibration may arise in the application of turbidometry for heat-treated food material. Neither method studied in this work was sufficiently sensitive without a pre-incubation step.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.1991.tb01168.x
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