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  • 1995-1999
  • 1985-1989  (11)
  • 1965-1969
  • 1988  (6)
  • 1986  (5)
  • 1
    Electronic Resource
    Electronic Resource
    Parametric study of AlAs/GaAs superlattice double-barrier diodes (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 207-209 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Quantum well diodes with barriers formed by thin, short-period binary AlAs/GaAs superlattices were fabricated and found to have very high peak-to-valley current ratios. The effects of varying the AlAs and GaAs layers in the barriers are studied. The peak current density is found to decrease by orders of magnitude for monolayer increases in the AlAs layer thicknesses. Tunneling current peaks due to both resonance levels in the quantum well and resonance levels in the superlattice barriers are observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100132
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  • 2
    Electronic Resource
    Electronic Resource
    Characterization of AlAs/GaAs superlattice barriers using electrical barrier height analysis (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 4765-4767 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Electrical barrier height measurements on n+-GaAs–insulator–n-GaAs structures with short-period AlAs/GaAs superlattices forming the insulator show the effective conduction-band discontinuity (ΔEC) of a superlattice barrier (SLB) to be defined by the lowest superlattice energy state. Five structures with different AlAs and GaAs SLB layer thicknesses are investigated. A SLB with GaAs layers greater than 10 monolayers is found to have a ΔEC defined by Γ-valley states in the GaAs layers, while a SLB with GaAs and AlAs layers less than 10 monolayers and with thicker AlAs layers than GaAs layers is found to have a ΔEC defined by X-valley states in the AlAs layers. The SLB with GaAs and AlAs layers less than 10 monolayers and thicker GaAs layers than AlAs layers behaves as a random alloy. Negative differential resistance is observed in the current-voltage characteristic of the sample whose barrier height is defined by Γ-valley states in the GaAs layers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341194
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Lymphatics of the Skin (1986)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of dermatology 25 (1986), S. 0 
    Details
    ISSN: 1365-4632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-4362.1986.tb03443.x
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  • 4
    Electronic Resource
    Electronic Resource
    Flow mechanisms in dense silica-metal oxide-water suspensions (1988)
    Springer
    Rheologica acta 27 (1988), S. 76-81 
    Details
    ISSN: 1435-1528
    Keywords: Densesuspension ; metal oxide ; silica ; settling ; plasticflow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The rheological properties of dense silica in water suspensions (approx. 50% solids by volume) containing additions of metal oxides were examined. Metal oxides used were ferric, zinc and stannic. To prevent settling, testing was performed in a rheometer which was modified to provide for continual stirring of the materials. Relatively small oxide additions had the effect of thickening the mixtures and making them non-Newtonian. Different rate-limiting steps for flow were identified depending on the particular mixture, testing temperature and shear strain rate. Flow could be described using empirical equations which are identical to those often used to describe plastic flow in solid crystalline materials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01372453
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  • 5
    Electronic Resource
    Electronic Resource
    Increased platelet thromboxane receptor sensitivity in diabetic patients with proliferative retinopathy (1986)
    Springer
    Diabetologia 29 (1986), S. 471-474 
    Details
    ISSN: 1432-0428
    Keywords: Platelets ; thromboxane sensitivity ; cAMP ; proliferative retinopathy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Platelet aggregation to collagen in 12 Type 1 (insulin-dependent) diabetic patients with background retinopathy and 12 Type 1 diabetic patients with proliferative retinopathy was compared with an age- and sex-matched control group. An analogue of prostaglandin H2, 11,9 epoxymethano-prostaglandin H2, which directly stimulates thromboxane receptors, and EP 092, which is a competitive thromboxane A2 receptor antagonist, were used to investigate changes at platelet thromboxane receptor level in these groups. The concentration of collagen (EC50) required to give 50% of maximum aggregation did not differ between the two diabetic groups and the control group. However, platelets from the proliferative retinopathy group were significantly more sensitive to the thromboxane mimetic (11,9 epoxymethano-prostaglandin H2) (p 〈 0.005) than the background retinopathy and control groups. This change may be a factor in the development of proliferative retinopathy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00453495
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  • 6
    Electronic Resource
    Electronic Resource
    Chemical corrosion of E-glass fibres in neutral phosphate solutions (1986)
    Springer
    Journal of materials science 21 (1986), S. 2175-2178 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Following local reports of failure of glass reinforced plastic (GRP) tanks used for the storage of ammonium orthophosphate fertilizer, the effect of phosphate solutions on the strength retention of E-glass fibre was investigated. Although solutions (1 to 5 mol dm−3) of mineral acids are known to corrode E-glass fibre, phosphoric acid solution (3 mol dm−3; pH 1.55) is essentially inert and strength retention of the glass fibre after 15 days exposure is the same as the water control. However, as the pH is raised strength retention is diminished and a minimum is observed around pH 7 to 8. A chemical explanation of this behaviour is put forward in terms of leaching and complex formation with calcium and magnesium ions. Although not nearly as corrosive as other agents, evidence suggests that phosphate solutions do corrode E-glass fibre and this should be borne in mind when GRP materials are used in such chemical environments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00547966
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  • 7
    Electronic Resource
    Electronic Resource
    The effect of monensin on intracellular transport and secretion of α-amylase isoenzymes in barley aleurone (1986)
    Springer
    Planta 167 (1986), S. 252-259 
    Details
    ISSN: 1432-2048
    Keywords: Aleurone (enzyme secretion) ; α-Amylase ; Gibberellin and enzyme secretion ; Hordeum (enzymes) ; Monensin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of monensin on the secretion of α-amylase and other enzymes from the aleurone layer of barley (Hordeum vulgare L. cv. Himalaya) was studied by electrophoresis followed by fluorography and by pulse-chase and organelle-isolation experiments. Monensin markedly inhibits the secretion, but not the synthesis, of α-amylase, acid phosphatase, and at least four other proteins from the aleurone layer. Monensin treatment causes α-amylase to accumulate within the protoplast, but its effect on the different α-amylase isoenzymes is not equal. The accumulation of isoenzyme 2 is not influenced by monensin while isoenzymes 1, 3 and 4 are not secreted but rather accumulate in the cell when monensin is included in the incubation medium. The α-amylase and acid-phosphatase activities which accumulate within the aleurone cells following treatment with monensin are localized in an organelle having a buoyant density greater than that of endoplasmic reticulum and less than that of mitochondria. In pulse-chase experiments with [35S]methionine, labelled proteins accumulate in this organelle in the presence of monensin and do not appear in the incubation medium. We conclude that monensin inhibits the secretion of proteins from the barley aleurone layer by influencing their intracellular transport.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00391423
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  • 8
    Electronic Resource
    Electronic Resource
    Estimating viability of plant protoplasts using double and single staining (1986)
    Springer
    Protoplasma 135 (1986), S. 80-87 
    Details
    ISSN: 1615-6102
    Keywords: Barley aleurone ; Fluorescein diacetate ; Propidium iodide ; Protoplasts ; Viability determination ; Vital stains
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The utility of numerous dyes for determining the viability of barley (Hordeum vulgare L. cv. Himalaya) aleurone protoplasts was studied. Protoplasts isolated from the barley aleurone layer synthesize and secrete α-amylase isozymes in response to treatment with gibberellic acid (GA) and Ca2+. These cells also undergo dramatic morphological changes which eventually result in cell death. To monitor the viability of protoplasts during incubation in GA and Ca2+, several types of fluorescent and nonfluorescent dyes were tested. Evans blue and methylene blue were selected as nonfluorescent dyes. Living cells exclude Evans blue, but dead cells and cell debris stain blue. Both living and dead cells take up methylene blue, but living cells reduce the dye to its colorless form whereas dead cells and cell debris stain blue. The relatively low extinction coefficient of these dyes sometimes makes it difficult to distinguish blue-stained cells against a background of blue dye. Several types of fluorescent dyes were tested for their ability to differentially stain dead or living cells. Tinopal CBS-X, for example, stains only dead cells, and its high extinction coefficient allows its ultraviolet fluorescence to be recorded even when preparations are simultaneously illuminated with visible light. To double-stain protoplasts, the most effective stain was a combination of fluorescein diacetate (FDA) and propidium iodide (PI). By employing a double-exposure method to record the fluorescence from cells stained with both FDA and PI, dead and living cells could be distinguished on the basis of fluorochromasia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01277001
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  • 9
    Electronic Resource
    Electronic Resource
    Monensin inhibits the secretion of α-amylase but not polysaccharide slime from seedling tissues ofZea mays (1988)
    Springer
    Protoplasma 142 (1988), S. 36-45 
    Details
    ISSN: 1615-6102
    Keywords: α-Amylase ; Corn (Zea mays) seedlings ; Growth ; Monensin ; Polysaccharide slime ; Secretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The effect of monensin on polysaccharide slime secretion by root tips of corn (Zea mays) was studied. Various treatment times and ionophore concentrations were tested: none resulted in inhibition of slime secretion. Because monensin changes the pH of the medium, its effect was also monitored in strongly buffered media and at different pH's. Even in such media, monensin did not inhibit slime secretion. We also measured the effect of the drug after a pulse with [3H]fucose or a pulse followed by a chase. The amount of labeled slimed secreted was not altered by the ionophore. However, 10μM monensin affected the development of root tips and drastically reduced their growth. We showed that monensin inhibits the secretion of α-amylase by the scutellum of the same plantlet. The importance of the nature of the secretory compound in relation to monensin inhibition of its secretion is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01273224
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  • 10
    Electronic Resource
    Electronic Resource
    Effects of Ga3 and Ca2+ on barley aleurone protoplasts: a freeze-fracture study (1988)
    Springer
    Protoplasma 146 (1988), S. 157-165 
    Details
    ISSN: 1615-6102
    Keywords: Calcium ; Endomembrane system ; Enzyme secretion ; Freeze fracture ; Gibberellic acid ; Protoplasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Freeze-fracture electron microscopy was used to study changes in the endomembrane system of barley (Hordeum vulgare L. cv. Himalaya) aleurone protoplasts. Protoplasts were used for this study because their response to calcium and the plant hormone gibberellic acid (Ga3) can be monitored prior to rapid freezing of cells for electron microscopy. Protoplasts incubated in Ga3 plus Ca2+ secrete elevated levels of a-amylase relative to cells incubated in Ga3 or Ca2+ alone. The endoplasmic reticulum (ER) and Golgi apparatus of protoplasts incubated in Ga3 plus Ca2+ undergo changes that are well correlated with the synthesis and secretion of a-amylase. The ER, which appears as short, single sheets of membrane in Ca2+-and Ga3-treated protoplasts, exists as a series of long fenestrated stacks of membranes following incubation in Ga3 plus Ca2+. The Golgi apparatus is also more highly developed in protoplasts treated with Ga3 plus Ca2+. This organelle is larger and has more vesicles associated with its periphery in protoplasts that actively secrete a-amylase. Evidence that the Golgi apparatus participates in a-amylase secretion is also provided by experiments with the ionophore monensin, which causes pronounced swelling of Golgi cisternae and inhibits the secretion of a-amylase. We interpret these observations as showing that the ER and Golgi apparatus of barley aleurone participate in the intracellular transport and secretion of a-amylase. The plasmalemma (PF face) of barley aleurone protoplasts shows a high density of intramembranous particles (IMPs) which, in general, are evenly distributed. Occasionally, ordered arrays of IMPs are observed, possibly resulting fro m osmotic stress. after 48 hours the plasmalemma of some Ga3-treated protoplasts show particle-free areas considered to be indications of senescence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01405925
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