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  • 1
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 1603-1605 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have observed a significant persistent photoconductivity effect in narrow InGaAs/InP quantum wells grown by metalorganic vapor phase epitaxy. This effect enables a detailed study of transport parameters as a function of the electron density. In this way, the interface roughness scattering can be separated from the strongly density dependent Coulomb scattering. For different preparation conditions, we find a strong correlation between the amount of interface roughness scattering and structural data of the interface. The ratio of quantum to classical scattering times remains (very-much-less-than)1 even in the case when Coulomb scattering is not the predominant scattering mechanism. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 412-414 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Morphological and physical properties of Al0.48In0.52As/Ga 0.47In0.53As heterostructures grown by molecular beam epitaxy, lattice relaxed on GaAs substrates and lattice matched on InP substrates, are presented. Both a quaternary linear and step graded lattice relaxed buffer concept is implemented to accomodate the lattice mismatch between the GaAs substrate and the Al0.48In0.52As/Ga 0.47In0.53As layer sequence. The surface morphology and the transport properties of Al0.48In0.52As/Ga0.47In0.53As high electron mobility transistor structures were studied by atomic force microscopy and Hall effect measurements, respectively. Optical properties were investigated by low temperature photoluminescence experiments on quantum well structures. The linear graded buffer approach was found to result in superior heterostructure properties due to the two dimensional growth mode during the whole growth process resulting in the typical cross hatched surface morphology. In contrast, the use of step graded buffer layers resulted in three dimensional layer growth and inferior layer quality. However, by increasing the number of steps, i.e., reducing the change in the lattice constant for each step and thus approaching a linear grading, two dimensional growth is recovered. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 104 (1996), S. 583-586 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Uncatalyzed gallic acid oscillating system has been investigated in a continuously fed stirred tank reactor (CSTR). In the [Bromate]0–[Bromide]0 concentration space, a region has been located where a bistability is observed between an oscillatory branch and a flow branch. To our knowledge this is the first evidence of bistability in an uncatalyzed bromate oscillator. Some observations have been explained in terms of the skeleton mechanism proposed in the past. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 117 (1995), S. 6372-6373 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 7 (1995), S. 0 
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Rehabilitation of locomotion in spinal cord (s.c.) injured patients is unsatisfactory. Here we report the effects of a novel ‘Laufband (LB; treadmill) therapy’ based on ‘rules of spinal locomotion’ derived from lower vertebrates. Eighty-nine incompletely paralysed (44 chronic and 45 acute) para- and tetraplegics underwent this therapy, then were compared with 64 patients (24 chronic and 40 acute) treated conventionally. The programme consisted of daily upright walking on a motor driven LB initially with body weight support (BWS) provided by a harness and assisted limb movements by the therapists when necessary. Forty-four chronic patients with different degrees of paralysis undertook the programme for 3-20 weeks (median = 10.5), 0.5–18 years after S.C. damage. At the onset of LB therapy 33/44 patients were wheelchair-bound (no standing and/or walking without help by others) compared with 25 at completion of LB therapy, i.e. 76% had learned to walk independently, 7 patients with help. Only 1 subject did not improve. It was striking that voluntary muscle activity in the resting position was still low in several patients who had gained walking capability. Eleven patients who could already walk before LB therapy improved in speed and endurance. Of the 44 patients, six were capable of staircase walking before LB therapy compared with 34 afterwards. In order to validate the apparent superiority of LB therapy two types of comparisons were performed. In a ‘temporal’ control 12 spastic paretic patients, still wheelchair-bound after the period of postacute conventional therapy, performed LB immediately thereafter. After completion of LB therapy nine of these patients had learned to walk without help from others. In another control, two groups of chronic patients, matched in type of injury, time after injury (1 or more years) and history of previous rehabilitation (one or several periods of conventional therapy), were compared. One group underwent LB therapy (n= 29), the other conventional therapy (n= 24) for similar periods of time. From 18 wheelchair-bound patients, 14 became independent walkers after LB, but only 1/14 after conventional therapy. From 45 acute patients 92% (33/36) of those wheelchair-bound at the onset of LB therapy became independent, but only 50% (12/24) after conventional therapy (n= 40). It is noteworthy that voluntary muscle activity at rest was similar in both groups. The presumed underlying mechanisms are discussed in the light of the absence of any apparent effects in seven functionally completely paralysed paraplegic persons.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of cutaneous pathology 24 (1997), S. 0 
    ISSN: 1600-0560
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Increasing evidence suggests involvement of integrins and CD44 isoforms in the pathogenesis of psoriasis, contributing to uncontrolled keratinocyte proliferation, neovascularization, and invasion of inflammatory cells. We have analyzed immunohistochemically in situ expression of integrins (CD29, CDw49b, CDw49c, CDw49e, CDw49f) and CD44 isoforms (CD44 standard, CD44 var/v6, CD44 v10) on frozen sections of normal and psoriatic skin (nonlesional skin, lesional skin before and along with topical calcitriol treatment). We did not observe visual changes of immunoreactivity in normal as compared to nonlesional psoriatic skin, while the staining pattern of CDw49c, CDw49f, and CD29 was severely altered in untreated lesional psoriatic skin. Most markedly, CDw49c, CDw49f, and CD29 were focally upregulated in suprapapillar epidermal compartments of lesional psoriatic skin, a staining pattern that is in accordance with the phenomenon that was described by Pinkus as ‘squirting papilla’. Additionally, an increased proportion of inflammatory and endothelial cells revealed immunoreactivity for CD44(std.) in untreated lesional psoriatic as compared to nonlesional psoriatic or normal skin. After 8 weeks of topical calcitriol treatment (15 μg/g ointment), the staining pattern for CDw49c, CDw49f and CD29 was markedly changed in epidermis of lesional psoriatic skin, reverting to the staining pattern characteristic for the nonlesional psoriatic or normal human skin, although epidermal expression of CDw49f was still upregulated and CDw49e-, CDw49f-, CD29-, and CD44(std.)- immunoreactive inflammatory and endothelial cells were still to be found in the dermal compartment.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The efficacy and tolerance of short-term immunotherapy (STI) by seven preseasonal injections of tree-pollen allergens (ALK7 FrUhbltihermischung®) was investigated in a double-blind, placebo-controlled, multicenter study with 111 rhinoconjunctivitis patients. Nasal and bronchial symptoms simultaneously analyzed, and nasal symptoms as a single end point, but not the overall score of nasal, bronchial, and conjunctival symptoms, showed a significantly lower increase with STI during birch-pollen exposure (both P= 0.033, n= 105, Mann-Whitney U-test). However, a selective analysis with patients from centers with high recruitment figures (nS10 patients, n=29 STI, n=32 placebo) showed a significantly lower increase of nasal, bronchial, and overall symptom score (STI 11.0 vs placebo 18.0, P=0.001, U-test). STI had equidirected effects on conjunctival, nasal, and bronchial symptoms analyzed as multiple end points, although conjunctival symptoms were not significantly different as a single end point. The seasonal increase in drug use was reduced by 62% in the STI group compared with placebo (P=0.032, Mest), Specific IgG4 increased only after STI (P〈0,001); IgE was not significantly different. Eosinophil cationic protein remained unchanged with STI, but significantly increased with placebo in the pollen season (P=Qm3). STI was well tolerated. In conclusion, STI was shown to be efficacious and safe for the treatment of patients with tree-pollen rhinoconjunctivitis.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 26 (1996), S. 1217-1223 
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Aluminium alloys were tested in Al/O2 cells with strongly acidic electrolytes containing minor amounts of chloride ions. The faradaic efficiency, the maximum discharge capacity and the peak power of various Al/O2 cells were evaluated. The temperature dependence of the faradaic efficiency was measured for an Al/O2 cell over the temperature range from 15 to 50°C. With a zinc-containing aluminium alloy, a faradaic efficiency of 84% and a cell voltage of 1.6 V at open circuit and 0.7 V at 100 mA cm−2 could be reached. The highest peak power 120 mW cm−2, was obtained with an Al-Zn/Sn alloy. On the basis of the solubility of the anode products in the electrolyte, a limiting specific energy of 70 Wh kg−1 was estimated. The cell voltage depends on the Al-alloys and on the catalyst used in the oxygen electrode. The cell voltage could be increased by about 200 mV when replacing the Pt-catalysed oxygen electrode with a noble-metal-free (CoCAA/DCD) electrode.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 28 (1998), S. 895-898 
    ISSN: 1572-8838
    Keywords: zinc–air battery ; pasted zinc electrode ; cellulose ; cycle life
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract For the development of a long-lived, electrically rechargeable zinc–air battery the structure and wettability of pasted zinc electrodes were optimized. Pasted zinc electrodes containing 1 to 10% cellulose but having almost the same nominal capacities were prepared and tested in zinc/oxygen cells. The effect of discharge rate on cell voltage and delivered capacity, as well as the maximum power, were measured. Furthermore, cell charge–discharge behaviour and cycle life were examined. After different times of operation, the porosity and the pore size distribution of the pasted zinc electrodes were measured by means of mercury porosimetry. The cycle life and peak power drain capability of the Zn/oxygen battery could be substantially improved by the addition of 10wt% cellulose to the pasted zinc electrode.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 97 (1995), S. 503-510 
    ISSN: 1434-6036
    Keywords: 61.55.F
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have investigated numerically using the Metropolis Monte Carlo algorithm two-dimensional systems of about 3000 classical particles interacting via a Lennard-Jones potential and being subjected to periodic boundary conditions. In this model we consider metastable structures of small crystalline grains which are randomly oriented relative to each other and which are interconnected by a network of boundaries. The atomic structure within the grains being composed of about 500 atoms each is a nearly ideal triangular lattice. The network of boundaries however has a highly defective structure which is determined by the boundary conditions enforced by the crystalline grains. It is the objective of our work to develop a conceptually simple model for nanocrystalline materials, which can be used for a qualitative description of their complex properties. The main ingredient of the model is its property to relax into a metastable state consisting of intrinsically well ordered crystalline grains connected by a highly defective intergranular component. For that state we compute the static structure factor and the pair correlation function.
    Type of Medium: Electronic Resource
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