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  • 1985-1989  (8)
  • 1980-1984
  • 1940-1944
  • 1986  (8)
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  • 1985-1989  (8)
  • 1980-1984
  • 1940-1944
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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 3631-3640 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have characterized the effects of Be+ implantation and controlled-atmosphere annealing on the structure of Ga(AsP)/GaP strained-layer superlattices (SLSs). Damage and strain distributions within the implanted layers were examined by cantilever-beam bending measurements, double-crystal x-ray rocking curves, and a variety of ion-channeling techniques. Implantation-induced displacement damage produces additional stress in the SLS, in this case reaching 4.5×109 dyn/cm2, a value comparable to that of the built-in stresses in these SLSs. The depth distribution of ion damage as measured by ion channeling agrees well with the predictions of the trim code, although substantial recovery occurs during the room-temperature implant. Rocking curve analysis indicates that the interlayer strain in the SLS is retained despite the ion damage, and that the ion damage can be modelled as an independent additional source of strain in the as-implanted structure. The linear expansion of the layers due to point defect generation for the 1×1015 Be/cm2 implant is determined to be approximately 0.3% by all three techniques. After controlled-atmosphere annealing at the nominal SLS growth temperature, both the x-ray and ion-channeling measurements indicate removal of the implant damage with the as-grown strain retained and no resolvable intermixing of the layers in the SLS. These results demonstrate that ion-implantation technologies developed for bulk semiconductors can successfully be applied to strained-layer superlattice systems.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated the properties of Ga(AsP)/GaP strained-layer superlattices (SLSs) that have been doped by implantation of 1×1015/cm2, 75 keV Be+ followed by controlled-atmosphere annealing at 825 °C for 10 min. Our results indicate that doping of these strained-layer superlattices without disordering is a viable process. Liquid-helium temperature photoluminescence suggests a binding energy for the implanted acceptors of 50 meV, consistent with that of beryllium in GaP-based alloys. The implantation-doped regions exhibit room-temperature electrical activation of 15% and hole mobilities of 20 cm2/V s, consistent with the values expected for type-converted GaP-based alloys. SLS diodes fabricated by this process exhibit excellent rectification properties, with a forward turn-on voltage of approximately 1.8 V and low values of room-temperature reverse leakage current densities. Diodes formed from SLSs with original n-type doping of 1×1017/cm3 have typical reverse leakage current densities of 1×10−7 A/cm2 at −10 V, despite the depletion region penetrating approximately ten interfaces of the SLS at this bias. Deep-level transient spectroscopy demonstrates the existence of defect centers, whose densities and signatures are similar to those found in ion-implanted GaP. The implanted photodiodes exhibit a wavelength-dependent photoresponse characteristic of grown-junction SLS photodetectors in the same chemical system. Examination of the spatial response of the photodiodes to a tightly focussed (FWHM=2.45 μm) laser beam at a wavelength of 488 nm indicates that the photoresponse from the device is uniform to within 10% for regions away from the edges of the implanted regions. Modelling of the wavelength-dependent and the spatially dependent photoresponse allows an estimate of minority-carrier diffusion lengths for electrons and holes of 1.0 μm parallel to the SLS layers and 0.1 μm perpendicular to the SLS layers. The excellent electrical and optical properties of the implanted and annealed SLS materials implies additional device applications for these novel materials.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 1131-1134 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have examined the properties of (InGa)As/GaAs strained-layer superlattices (SLSs) that have been disordered by implantation of 5×1015/cm2, 250 keV 64Zn+ followed by controlled atmosphere annealing at 680 °C for 30 min. Ion channeling techniques indicate that the Zn-disordered regions of the SLS contain extensive crystalline damage after annealing. Simulations of the disordering process using an analytic ion range code predict that the electrical junction resulting from the implantation process is located outside the disordered region of the SLS in both the vertical and the lateral directions. Junction electroluminescence intensity for given drive current densities from the Zn-disordered SLS devices is comparable to that from reference Be-implantation-doped (SLS retained) devices and greatly exceeds that from heavily dislocated grown-junction mesa diodes in the homogeneous alloy of the average SLS composition; this result is consistent with the results of the simulations. This study demonstrates that implantation disordering can be as useful for strained-layer systems as for less severely mismatched heterojunction systems.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Annals of operations research 5 (1986), S. 463-484 
    ISSN: 1572-9338
    Keywords: Branch and bound design ; tree enumeration strategies ; discrete nonlinear programs ; nonlinear integer test problems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract This paper is concerned with computational experimentation leading to the design of effective branch and bound algorithms for an important class of nonlinear integer programming problems, namely linearly constrained problems, which are used to model several real-world situations. The main contribution here is a study of the effect of node and branching variable selection and storage reduction strategies on overall computational effort for this class of problems, as well as the generation of a set of adequate test problems. Several node and branching variable strategies are compared in the context of a pure breadth-first enumeration, as well as in a special breadth and depth enumeration combination approach presented herein. Also, the effect of using updated pseudocosts is briefly addressed. Computational experience is presented on a set of eighteen suitably-sized nonlinear test problems, as well as on some random linear integer programs. Some of the new rules proposed are demonstrated to be significantly superior to previously suggested strategies; interestingly, even for linear integer programming problems.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Inflammation research 18 (1986), S. 550-554 
    ISSN: 1420-908X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A method has been developed for thein vivo measurement of leucocyte chemotaxis in response to the bacterial chemotactic peptide F-met-leu-phe (FMLP). Polyurethane sponges were pre-treated with FMLP and implanted subcutaneously in rats and after a suitable interval removed for determination of leucocyte influx.In vivo concentration gradients of chemotactic factors within intact sponges were shallow and leucocyte accumulation unsatisfactory. Accordingly a cored sponge model was developed in which the cylindrical core only was treated with chemotactic factor and the sponge reassembled prior to subcutaneous implantation. Steep concentration gradients were established within the outer sponge matrix with marked effects on leucocyte accumulation, permitting studies of the time course ofin vivo chemotaxis. With cored sponges test to control cell number ratios were maximal at 4 hours using both free and albumin-bound FMLP. This model ofin vivo chemotaxis may prove useful in several areas of inflammation research.
    Type of Medium: Electronic Resource
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  • 6
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    Unknown
    The Hague : Periodicals Archive Online (PAO)
    The Journal of Value Inquiry. 20:1 (1986) 19 
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Tropical animal health and production 18 (1986), S. 209-216 
    ISSN: 1573-7438
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé On decrit un test immuno-enzymatique (TIE) modifié en phase solide, permettant la détection visuelle des anticorps antibovipestiques dans les sérums de bovins et de chèvres. Des antigènes antibovipestiques repartis par points (d ou Point-TIE) sont adsorbes sur un papier de nitrocellulose (NC) et les sites d’absorption des réactifs sont bloqués avec du lait éirémé en poudre. Après immersion dans des sérums de bovins ou de chèvres à tester, les anticorps fixés sont mis en evidence par une IgG, respectivement anti-boeuf ou anti-chèvre, conjuguée a une peroxydase. Après dégradation enzymatique d’un substrat contenant du peroxyde d’hydrogene et de l’aminoethylcarbazole (AEC), on visualise aisement les reactions positives comme des points brun-rougeâtres. Le Point-TIE est comparable au test de séro-neutralisation (SN) dans sa capacité de détection des anticorps dans les sérums de bovins sept ou 10 jours après l’infection (JPI) expérimental de la souche bovipestique attenuée Kabete ‘O’ (RBOK) (cultivée en cellules Vero) par combinaison des voies sous-cutanée (SC), intraveineuse (IV) et intranasale. Des anticorps antibovipestiques precoces (sept JPI) ont éte détectés dans un échantillon de serum de chèvre infectée experimentalement par le virus bovipestique par une combinaison de voies SC-IV, mais pas d’une autre chèvre infectée par voie nasale. La spécificité du test Point-TIE est égal a celle du test SN car les échantillons de sérums de ces animaux d’experience et de ceux inoculés avec un liquide de culture de cellules Vero non infectés, et possedant des titres SN de 0.3 ou inferieurs, se sont tous montrés negatifs en Point TIE. Le Point-TIE peut avoir des applications potencielles car c’est un test de terrain rapide, simple et économique pour le diagnostic de la peste bovine, la surveillance de la vaccination et d’autres études séro-épidemiologiques.
    Abstract: Resumen Se describe un inmunoensayo de fase sólida modificada, para la detección visual de anticuerpos contra el virus de rinderpest, en suero bovino y caprino. Pequeñas cantidades de antígenos en forma de puntos, del virus de rinderpest, se adsorbieron en papel nitrocelulosa, siendo las zonas adsortivas reactivas bloqueadas con leche descremada. Despues de la inmersión en suero bovino o caprino, los anticuerpos adheridos se hicieron reaccionar con un conjugado de peroxidasa IgG, antibovino y anticaprino respectivamente. Las reacciones positivas se visualizaron fácilmente, como puntos cafe-rojizos, despues de la degradación del substrato el cual contenía peróxido de hidrógeno y amino-etilcarbazol. El inmunoensayo enzimático de punto fue comparable a la prueba de seroneutralización, en la abilidad para detectar anticuerpos en suero bovino, siete a diez días despues de la infección experimental con cepas vivas atenuadas del virus de rinderpest (Kabete ‘O’) cultivado en células Vero, infección llevada a cabo mediante la combinación de las rutas subcutánea, intranasal e intravenosa. Siete días post-inoculación experimental, se detectaron anticuerpos del virus de rinderpest en el suero de una cabra que había sido infectada mediante la combinación de las rutas subcutánea e intravenosa. No se encontraron anticuerpos en el suero de otra cabra inoculada vía intranasal. La especificidad del inmunoensayo enzimático de punto, fue similar a la obtenida con la prueba de seroneutralización, debido a que las muestras de suero colectadas de los animales arriba mencionados y de otros que habían sido inoculados con cultivos de células Vero no infectados, con títulos de seroneutralización de 0.3 o menores, fueron todos negativos a la prueba de inmunoensayo enzimático. Esta última, puede tener aplicación potencial como herramienta rápida, simple y económica en el campo, para el diagnóstico de rinderpest. Tambien podría tener aplicación en campañas de vigilancia vacunal y cualquier otro estudio seroepidemiológico.
    Notes: Summary A modified solid phase enzyme immunoassay (EIA) is described for visual detection of anti-rinderpest virus (RPV) antibodies in cattle and goat sera. Dots of RPV antigens were adsorbed to nitrocellulose (NC) paper (hence Dot-EIA) and the adsorptive reactive sites were blocked with skim milk powder. After immersion in bovine or caprine test serum bound antibodies were reacted with a peroxidase-conjugated anti-bovine or anti-caprine IgG (H & L), respectively. Positive reactions were easily visualized as red-brown dots after enzyme degradation of a substrate containing hydrogen peroxide and aminoethylcarbazole (AEC). The Dot-EIA was comparable to the serum neutralisation (SN) test in its ability to detect antibody in bovine sera seven or ten days after experimental infection (DPI) with live attenuated Kabete “O” (RBOK) strain of RPV (grown in Vero cells) by a combination of subcutaneous (s/c), intravenous (i/v) or intranasal (i/n) routes. Early (seven DPI) RPV antibodies were detected in a serum sample from one goat experimentally infected with RPV by combined s/c-i/v routes but not in another goat only infected intranasally. The specificity of the Dot-EIA was equal to that of the SN test, as serum samples, collected from these experimental animals and those inoculated with non infected Vero cell culture fluid, with SN titres of 0·3 or lower were all negative by Dot-EIA. The Dot-EIA may have potential application as a rapid, simple and economical field test in diagnosis of rinderpest, vaccination surveillance and other seroepidemiological studies.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Tropical animal health and production 18 (1986), S. 113-114 
    ISSN: 1573-7438
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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