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  • 1
    Electronic Resource
    Electronic Resource
    Strain relaxation behavior of InxGa1−xAs quantum wells on vicinal GaAs (111)B substrates (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 1541-1543 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A number of reports have suggested that InGaAs/GaAs (111)B strained layer epitaxy has the prospect of reaching a higher critical layer thickness than that which can be achieved for (001) substrates. This has motivated a study of the relaxation mechanism of InGaAs/GaAs (111)B quantum wells with high In content (0.12〈x〈0.35). Transmission electron microscopy has revealed the existence of a different misfit dislocation (MD) configuration for high In contents (x〉0.25), which, we believe, has not been reported until now. For such compositions, plastic relaxation takes place through a polygonal network of MDs, which have Burgers vectors in the interface plane. The origin of this network is an unusual dislocation source that occurs through the formation of a three-pointed star-shaped configuration. The characteristics of this misfit dislocation network, which has a higher misfit relieving component and a glide plane coincident with the interface plane, imply a reduction of the previous critical layer thickness estimates for high In content InGaAs/GaAs (111)B heterostructures. However, we observe that none of the (111)B samples shows evidence of a transition to a three-dimensional growth mode, which represents a significant advantage compared to the behavior of high In content quantum wells on (001) substrates. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1455691
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  • 2
    Electronic Resource
    Electronic Resource
    Hydraulic and photosynthetic co-ordination in seasonally dry tropical forest trees (2002)
    Oxford, UK : Blackwell Science, Ltd
    Plant, cell & environment 25 (2002), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In the present study the linkage between hydraulic, photosynthetic and phenological properties of tropical dry forest trees were investigated. Seasonal patterns of stem-specific conductivity (KSP) described from 12 species, including deciduous, brevi-deciduous and evergreen species, indicated that only evergreen species were consistent in their response to a dry-to-wet season transition. In contrast, KSP in deciduous and brevi-deciduous species encompassed a range of responses, from an insignificant increase in KSP following rains in some species, to a nine-fold increase in others. Amongst deciduous species, the minimum KSP during the dry season ranged from 6 to 56% of wet season KSP, indicating in the latter case that a significant portion of the xylem remained functional during the dry season. In all species and all seasons, leaf-specific stem conductivity (KL) was strongly related to the photosynthetic capacity of the supported foliage, although leaf photosynthesis became saturated in species with high KL. The strength of this correlation was surprising given that much of the whole-plant resistance appears to be in the leaves. Hydraulic capacity, defined as the product of KL and the soil–leaf water potential difference, was strongly correlated with the photosynthetic rate of foliage in the dry season, but only weakly correlated in the wet season.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.2002.00919.x
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  • 3
    Electronic Resource
    Electronic Resource
    Relations between stomatal closure, leaf turgor and xylem vulnerability in eight tropical dry forest trees (2003)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 26 (2003), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: This study examined the linkage between xylem vulnerability, stomatal response to leaf water potential (ΨL), and loss of leaf turgor in eight species of seasonally dry tropical forest trees. In order to maximize the potential variation in these traits species that exhibit a range of leaf habits and phenologies were selected. It was found that in all species stomatal conductance was responsive to ΨL over a narrow range of water potentials, and that ΨL inducing 50% stomatal closure was correlated with both the ΨL inducing a 20% loss of xylem hydraulic conductivity and leaf water potential at turgor loss in all species. In contrast, there was no correlation between the water potential causing a 50% loss of conductivity in the stem xylem, and the water potential at stomatal closure (ΨSC) amongst species. It was concluded that although both leaf and xylem characters are correlated with the response of stomata to ΨL, there is considerable flexibility in this linkage. The range of responses is discussed in terms of the differing leaf-loss strategies exhibited by these species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.2003.00975.x
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  • 4
    Electronic Resource
    Electronic Resource
    Water relations of tropical dry forest flowers: pathways for water entry and the role of extracellular polysaccharides (2003)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 26 (2003), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Many trees in tropical dry forests flower during the dry season when evaporative demand is high and soil water levels are low. In this study the factors influencing the water balance of flowers from three species of dry forest trees were examined. Flowers had greater mucilage contents than leaves, high intrinsic and absolute capacitances, long time constants for water exchange and high transfer resistances. Flower water potentials were higher than in leaves and did not fluctuate over the lifespan of the flower. Flower water content also remained constant even though evaporation rates were high, suggesting that water was being supplied from the stem. In two of the species, the water potential gradient between flowers and leaves was opposite to that necessary for water transport from stem to flowers through the xylem, and it was therefore hypothesized that water may enter the flower through the phloem. Calculations showed that nectar production in these flowers could drive a sink of sufficient magnitude to allow water input via the phloem equal to water lost from the flower to the atmosphere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.2003.00998.x
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  • 5
    Electronic Resource
    Electronic Resource
    Short-term storage of ova of common carp and tench in extenders (2001)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 59 (2001), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In a study of the effect of short-term storage on the hatching rate of common carp Cyprinus carpio and tench Tinca tinca ova in vitro in various extenders at 21° C under aerobic conditions, the best extender for 30 min storage for common carp appeared to be Dettlaff 1. This gave the same hatching rate as controls without extender (55%v. 56%). For 60 min storage of ova, the best extenders were Dettlaff 2 (24% hatching rate) and Dettlaff 3 (30%), but hatching was significantly lower than in the control (58%). In carp ovarian artificial fluid (CAF) extender, the hatching rate of common carp ova was also high after 10 min, but decreased to 12% after 30 min. In tench, the hatching rate of ova increased after 10 min storage in Dettlaff 5 extender (44%) compared to the control (41%) without extender. However, it was significantly lower after storage in Dettlaff 1, 2, 3, 4, 5 and CAF extenders for 20, 30 and 60 min, compared to controls. Malformations (10–50%) were observed in the tench second control groups without extender after 10, 20 and 30 min storage of ova.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.2001.tb02366.x
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  • 6
    Electronic Resource
    Electronic Resource
    N-(6-Amino-3,4-dihydro-3-methyl-5-nitroso-4-oxopyrimidin-2-yl) derivatives of glycine, valine, serine, threonine and methionine: interplay of molecular, molecular–electronic and supramolecular structures (2000)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 56 (2000), S. 882-892 
    Details
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: In each of N-(6-amino-3,4-dihydro-3-methyl-5-nitroso-4-oxopyrimidin-2-yl)valine, C10H15N5O4 (3) (orthorhombic, P212121), N-(6-amino-3,4-dihydro-3-methyl-5-nitroso-4-oxopyrimidin-2-yl)serine monohydrate, C8H11N5O5·H2O (4) (orthorhombic, P212121), and N-(6-amino-3,4-dihydro-3-methyl-5-nitroso-4-oxopyrimidin-2-yl)threonine, C9H13N5O5(5) (monoclinic, P21), the C-nitroso fragments exhibit almost equal C—N and N—O bond lengths: the C—N range is 1.315 (3)–1.329 (3) Å and the N—O range is 1.293 (3)–1.326 (3) Å. In each compound there are also very short intermolecular O—H...O hydrogen bonds, in which carboxyl groups act as hydrogen-bond donors to the nitrosyl O atoms: the O...O distances range from 2.440 (2) to 2.504 (4) Å and the O—H...O angles lie between 161 and 163°. An interpretation of the relationship between the unusual intramolecular bond lengths and the very short intermolecular hydrogen bonds has been developed based on database analysis and computational modelling. In each of (3)–(5) there is an extensive network of intermolecular hydrogen bonds, generating three-dimensional frameworks in (3) and (5), and two-dimensional sheets in (4).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108768100005437
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  • 7
    Electronic Resource
    Electronic Resource
    Spectrophotometric determination of titanium, zirconium and hafnium with pyridoxal 3-hydroxy-2-naphthoylhydrazone (1984)
    Springer
    Microchimica acta 84 (1984), S. 17-27 
    Details
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Synthese, Eigenschaften und analytische Anwendung von Pyridoxal-3-hydroxy-2-naphthoylhydrazon wurden beschrieben. Die Reaktionen von Titan(IV), Zirkon(IV) und Hafnium(IV) mit diesem Reagens wurden untersucht und die Stöchiometrie ihrer ternären Komplexe ermittelt. Photometrische Methoden für die Bestimmung dieser Ionen wurden vorgeschlagen und deren Selektivität untersucht.
    Notes: Summary The synthesis, characteristics and analytical applications of pyridoxal 3-hydroxy-2-naphthoylhydrazone are described. The reactions of titanium(IV), zirconium(IV) and hafnium(IV) with this reagent have been studied spectrophotometrically and the stoichiometries of the ternary complexes determined. Photometric methods for the determination of these ions are proposed, and the selectivity of these methods has been established.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01204154
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  • 8
    Electronic Resource
    Electronic Resource
    Three conjectures of combinatorial topology (1983)
    Springer
    Inventiones mathematicae 72 (1983), S. 507-507 
    Details
    ISSN: 1432-1297
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01398399
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  • 9
    Electronic Resource
    Electronic Resource
    The Effect of Fluid Content on the Mechanical Behaviour of Fractures in Chalk (2000)
    Springer
    Rock mechanics and rock engineering 33 (2000), S. 93-117 
    Details
    ISSN: 1434-453X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: Summary ¶The paper presents an experimental study on the effects of fluid content on the mechanical behaviour of natural fractures in chalk. The aims of the study are to provide better understanding of the mechanisms of chalk-fluid interaction, in general, and to explain the behaviour of petroleum chalk reservoirs during water injection, in particular. The experiments were carried out on Lägerdorf chalk using the direct shear apparatus. Two types of fluids were used in the tests: 1) water, and 2) synthetic oil. Lägerdorf chalk is a water-wet material which will develop capillary pressures upon contact with water. Initially saturating the chalk with oil will enhance the water wettability by inducing additional capillary forces between water and the non-wetting oil. In addition to the tests on fractured chalk samples, unconfined compression and direct shear tests on intact chalk samples were performed. The results showed significant differences in the strength and deformation characteristics of intact chalk initially saturated with different fluids. Intact water-saturated chalk showed lower deformation modulus (about 50%) and lower peak (also about 50%) and residual shear strength than the oil-saturated chalk. Water injection in initially oil-saturated fractures resulted in significant normal deformation under constant effective normal stress and shear stress relaxation under fixed shear displacement. The water-induced deformation occurred almost instantaneously after only a few cm3 of water had been injected into the fracture, and further injection of water did not increase the water-induced deformation. After water injection, fractures in initially oil-saturated chalk showed significantly lower normal and shear stiffnesses and lower shear strength. The weakening in shear is attributed partly to the reduction in the basic friction angle, φb, and this reduction was verified in a series of tilt tests to measure the frictional resistance between smooth edges of core samples of chalk. The reduction in the basic friction angle implies that the interaction of chalk with water is governed not only by capillary forces, as postulated in several previous studies, but also by chemical and/or physio-chemical effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s006030050037
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  • 10
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    Contribution of the H63D mutation in HFE to murine hereditary hemochromatosis (2003)
    National Academy of Sciences
    Details
    Publication Date: 2003-12-12
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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