Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Soil use and management 17 (2001), S. 0 
    ISSN: 1475-2743
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract. The aim of this study was to investigate the effects of water submergence depth on radial oxygen loss (ROL), soil solution chemistry and rice growth performance in acid sulphate soils in southern Vietnam. ROL was measured in a solution culture. In a separate pot experiment the impact of water submergence depth on rice growth and soil solution chemistry was studied. Three submergence depths were used in the two experiments (5, 10 and 15 cm). ROL declined with submergence depth and was significantly greater in young roots (with no root hairs) than in older roots. In the pot experiment rice growth and soil solution chemistry were clearly affected by the submergence depth. During the first crop at 5 cm submergence, there was a significantly higher yield and a higher oxidation state (pe+pH) compared to 10 or 15 cm submergence. The Fe concentration was significantly greater at the 5 cm depth compared to the 10 or 15 cm depth. SO42– reduction was delayed at the 5 cm depth. Rice yield was c. 25% less at the 15 cm than at the 5 cm depth. During a second crop, there was a substantial SO42- reduction and H2S formation and almost no significant effects of submergence depth on either soil solution chemistry or crop yield. In a field experiment with a dry-season rice crop, yield and Fe, Al and SO42– concentrations were higher at a shallow submergence depth than at greater depths in the same field, showing similar depth trends to those found during the first crop in the pot experiment. Farmers should be advised to use a shallow submergence depth and, if possible, avoid deep-rooted rice varieties. A conceptual model is suggested, which summarizes the relationships between ROL and soil solution chemistry.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 3214-3218 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We use photoluminescence to study residual transition metal contaminants in GaN layers, which are grown by the sandwich technique either on 6H-SiC substrate or on sapphire substrate. We observe three no-phonon lines in the near infrared optical region at 1.3 eV, 1.19 eV, and 1.047 eV caused by 3d transition metals. The appearance of GaN related host modes in the phonon sideband of these emissions proves that the luminescence centers are incorporated in the hexagonal GaN layers. In this paper we especially focus on the luminescence band with the no-phonon line at 1.047 eV. Temperature dependent photoluminescence measurements reveal an excited state splitting of 8 meV. In photoluminescence excitation spectroscopy we observe a further excited state at 1.6 eV with a fine structure splitting. The appearance of this excited state in the n-type samples gives evidence that the defect must already exist in its luminescent charge state without illumination. The experimental results on the 1.047 eV emission fit to a 4T2(F)→4A2(F) internal electronic transition of a transition metal with a 3d7 electronic configuration. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 1753-1757 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: SiGe single quantum wells grown pseudomorphically by solid source molecular beam epitaxy on Si substrates were investigated by low-temperature photoluminescence measurements. The study was meant to correlate efficient radiative recombination of SiGe quantum well structures to crystal growth temperatures. As a model system, nominally 4-nm-thick quantum wells with a Ge concentration of 20% were used and the influence of growth temperatures on photon energy, on full width at half maximum, and on photoluminescence intensity was examined. At low growth temperatures (500 °C or less), only a deep broad luminescence band is observed while at higher temperatures a phonon-resolved, near-band-edge emission is predominant until it disappears completely at about 1000 °C. A systematic study of the photoluminescence characteristics over the entire range of crystal growth temperatures where luminescence is observable at all, is reported and a "growth window'' for optimized photoluminescence features was determined. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 878-880 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: High quality, GaInAs, single quantum wells lattice matched to InP barriers, have been grown by metalorganic vapor phase epitaxy at reduced pressures and with the application of short growth interruptions at both heterointerfaces. The occurrence of multiple peaks in the 25 K cathodoluminescence spectrum of a sample containing nominally two single quantum wells is caused by terraces differing by one monolayer in thickness, ≈ 2.93 A(ring), in the same quantum well. For their observation as well defined excitonic emission peaks, the terraces must be larger in lateral extent than the free exciton Bohr diameter, namely, ≈ 350 A(ring). This number sets the lower boundary of the size of the terraces. Cathodoluminescence images were formed for the individual emission peaks and the contrast fluctuations observed with a lateral extent up to ≈ 2 μm give the upper boundary for the extended monolayer-flat terraces. So far this is the first direct observation of such large growth islands at the heterointerface of the GaInAs/InP system.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 2611-2613 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Indium composition variations in strained InGaAs/GaAs quantum wells grown on nonplanar substrates by molecular beam epitaxy have been analyzed by spatially and spectrally resolved low-temperature cathodoluminescence. For our growth conditions, the In adatom migration length on (100) facets has been determined to be ∼25 μm. A maximum relative increase of In incorporation of (approximately-equal-to)6% on (100) ridges is observed and is found to be strain independent (In composition) for quantum wells nominally 35 and 70 A(ring) thick with In composition of 0.10–0.22. Significantly asymmetric indium adatom migration is observed between adjacent (100) facets for ridges and grooves formed with (111)A and (311)A multifaceted sidewalls, indicating that multifaceting kinetically inhibits adatom migration. For structures designed for one-step growth of index-guided injection lasers with built-in nonabsorbing waveguides, we show that differences greater than 80 meV in the effective band gap of a 70 A(ring) quantum well can be achieved between the gain region and the nonabsorbing waveguide without relaxing the strain.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 972-974 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thickness variations in GaAs/AlGaAs quantum wells grown on patterned substrates by molecular beam epitaxy have been analyzed by spatially and spectrally resolved low-temperature cathodoluminescence. For the lower and upper (100) facets joined by an angled (311)A facet, relative increases in quantum well thicknesses up to (approximately-equal-to)6% and 20% are observed, respectively, in the vicinity of the intersection of the facets. Following an exponential behavior, the Ga adatom migration length is found to be in the range of 1–2 μm on both the lower and upper (100) facets and is independent of quantum well thickness. This migration length is orders of magnitude greater than previously reported for Ga adatoms during molecular beam epitaxy growth.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 1564-1567 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on deep-level transient spectroscopy investigations of the Mn acceptor level in GaAs, including measurements of the emission and capture of holes and of the capture of electrons. A comparison is made between electron capture rates obtained from space-charge techniques and from photoluminescence decay measurements.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 1033-1035 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on the structural and optical properties of GaN epitaxial layers grown on 6H-SiC. We employed the sublimation sandwich method to grow single crystal layers at high growth rates with free carrier concentrations of 2×1017 cm−3. Very narrow x-ray diffraction peaks of the GaN (0002) plane are obtained indicating the high quality of this system. These findings are directly reflected in the optical properties. The photoluminescence shows a single sharp exciton line with a half width of 4 meV. Impurity related donor acceptor transitions are seen with very weak intensities. However, at lower energies the internal luminescence transitions of the 3d transition metal ions Fe and V are observed.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Scandinavian journal of immunology 11 (1980), S. 0 
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: To compare the receptor patterns for mitogenic and non-mitogenic substances, surface glycoproteins of human lymphocytes were labelled with the lactoperioxidase-catalysed iodination technique and with a galactose oxidase-tritiated sodium borohydride technique. Labelled cells were detergent-solubilized, and the lysates were allowed to react with insolubilized purified mitogenic lectins, phytohaemagglutinin, leucoagglutinin and an insolubilized non-mitogenic lectin, oxidized leucoagglutinin. Lectin-reactive protein were eluted with sodium dodecyl sulphate (SDS) buffer. Cell membrane components reactive with anti-lymphocyte globulin (ALG) were retrieved by indirect immunoprecipitation with protein-A-bearing staphylococcus Cowan I strain (SaCI). Lectin-and ALG-reactive proteins were analysed by SDS polyacrylamide gel electrophoresis. Iodinated glycoproteins regularly showed four major components with molecular weight of 120,000, 70,000 60,000 and 43,000 daltons, respectively, on 7% gels. An additional broad peak in the molecular weight range 20,000–35,000 daltons found on 10% gels. Tritiated glycoproteins also showed four major components with MW 120,000, 70,000, 60,000 and 42,000, respectively, which reacted with lectin and ALG. In addition, ALG reacted with some glycoproteins with MW between 150,000 and 230,000 daltons. On 10% gels additional lectin and ALG-binding glycoproteins with MW around 30,000 daltons were found. The similarity in structures bound by mitogenic and non-mitogenic substances indicated that lymphocyte activation may depend on some properly conferred by the mitogen.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 97 (1993), S. 11332-11338 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...