Library

X
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
    Scattering mechanisms and defects in InP epitaxially grown on (001) Si substrates (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 4705-4712 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Carrier concentration and mobility of unintentionally doped InP layers, grown directly on Si using metal-organic vapor-phase epitaxy, have been studied. The formation of antiphase domains (APDs) was found to depend on annealing of the Si substrate in an AsH3 flow prior to epitaxial growth. Dislocation densities determined by the wet chemical delineation technique were (8±1)×107 cm−3, seemingly uncorrelated to APDs in the layers. In addition to a shallow donor and a compensating acceptor, a deep donor was observed affecting the temperature dependence of the free-electron concentration between 77 and 300 K. The electron mobility in this temperature range could be described in terms of the scattering mechanisms which are dominant in homoepitaxial InP, namely, scattering due to polar optical phonons, to ionized impurities, and to space charges. Electron scattering due to either of these mechanisms was strongly influenced by the occurrence of antiphase boundaries (APBs). The space-charge density as well as the degree of compensation of the epitaxial layers increases with the density of APBs. Degraded 300 K mobilities were obtained indicating the effect of local stress at the APB.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.358445
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Electronic degrees of freedom and unimolecular rate constants in metal clusters (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 10481-10484 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We calculate the modifications of the unimolecular rate constants for free metallic clusters due to thermally exited electronic degrees of freedom. The effect is essentially taken into account by substituting Helmholtz's free energy of the electronic system for the ground state energy. The activation energy pertaining to the electronic ground states of the mother and daughter cluster is then replaced by the first difference in Helmholtz's free energy. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.467866
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Fast and accurate current-voltage curves of metallic quantum point contacts (2000)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 1793-1803 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We present an experimental setup for measuring the electrical conductance through metallic quantum point contacts (QPCs) under constant or time-dependent bias voltage conditions. The response time of the setup is as short as 25 ns and typical bias voltages range from 10 mV to 2 V. A function generator is used as bias voltage supply. With this, voltage bursts with a frequency of up to 100 kHz can be applied to the QPCs, whereby current-to-voltage (I–V) curves can be acquired using a homebuilt, 30 MHz bandwidth I–V converter, and a 100 Msamples/s digital storage oscilloscope. Test experiments on resistors show that nonlinear contributions to the I–V curves are always less than 1% of the current for all applied voltages. From the slope of the I–V curves, the conductance can be determined with an accuracy better than 1%. The QPCs are formed between a single-crystal metal sample and the tip of a scanning tunneling microscope under clean ultrahigh vacuum conditions. We demonstrate how the setup can be used to capture the I–V curves of several metastable states in a Au QPC, as it breaks during a period of 200 μs at room temperature. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1150539
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Computer controlled probe diagnostic system and applications in a magnetized laboratory plasma (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2615-2622 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A computer controlled acquisition and evaluation system for electrostatic probes is presented. Fully automatic evaluation of the probe characteristics yields electron temperature, plasma potential, and density during the recording. Two-dimensional probe positioning is accomplished with stepping motors. The system is characterized by 12-bit probe current resolution and extremely wide probe voltage range (±130 V). It is tested in a collisionless argon magnetoplasma and compared to standard wave diagnostic techniques for magnetized plasmas, i.e., the resonance cone technique. The influence of the probe radius on the electron current in a magnetized plasma is studied experimentally. The two techniques yield identical density and temperature values within 20% accuracy and therefore show the reliable applicability of the automatic evaluation system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144660
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    On the concept of temperature for a small isolated system (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 114 (2001), S. 6518-6525 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The microcanonical temperature is shown to be a useful concept in calculations of the decay of a small isolated system with well defined energy. A simpler and more transparent description is obtained than in Klots' formulation of finite-heat-bath theory, where the system is represented by a canonical ensemble. As a further illustration of the utility of the microcanonical temperature concept, we discuss a formula derived by Dunbar for the probabilities for excitation of a single oscillator in a collection of harmonic oscillators with well defined total energy. This formula expresses the excitation probabilities in terms of the temperature for a canonical ensemble with mean energy equal to the energy of the system. However, a much improved accuracy is obtained if the canonical temperature and heat capacity are replaced by their microcanonical values. We justify this replacement through a modified derivation, in which the microcanonical temperature appears as the canonical temperature of a fictitious system with level density ρ′(E), the derivative of the level density ρ(E) of the collection of oscillators. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1357794
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Current-voltage curves of gold quantum point contacts revisited (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 708-710 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present measurements of current–voltage (I–V) curves on gold quantum point contacts (QPCs) with a conductance up to 4 G0 (G0=2e2/h is the conductance quantum) and voltages up to 2 V. The QPCs are formed between the gold tip of a scanning tunneling microscope and a Au(110) surface under clean ultra-high-vacuum conditions at room temperature. The I–V curves are found to be almost linear in contrast to previous reports. Tight-binding calculations of I–V curves for one- and two-atom contacts are in excellent agreement with our measurements. On the other hand, clearly nonlinear I–V curves are only observed when the sample has been cleaned in air. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.127093
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Lyme Arthritis: Oligoclonal Anti-Borrelia burgdorferi IgG Antibodies Occur in Joint Fluid and Serum (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Scandinavian journal of immunology 33 (1991), S. 0 
    Details
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The antibody response to Borrelia (B.) burgdorferi, and to measles virus as control antigen, was analysed by agarose isoelectric focusing (AIF) and immunoblot of joint fluid and serum from 10 patients with Lyme arthritis and 10 controls with rheumatoid arthritis. Among the Lyme arthritis patients, six had oligoclonal anti-B, burgdorferi IgG antibody bands in joint fluid and Corresponding serum, one patient had oligoclonal antibody bands in joint fluid only and also an elevated B. burgdorferi IgG in joint fluid to serum antibody ratio as evidence of intra-joint production of specific antibodies, and the remaining three patients were negative for oligoclonal-specific antibody bands. Absorption with B. burgdorferi imagen confirmed the specificity of the ofigoclonal antibody bands. They comigrated only partially on AIF with oligoclonal bands of total IgG and the specificity of most oligoclonal IgG in joint fluid and serum in Lyme arthritis remains undefined. Among the controls, no anti-B, burgdorferi IgG antibodies were detected by AIF and immunoblot. Instead. 9 of the 10 rheumatoid arthritis patients had oligoclonal anti-measles IgG antibody bands which were restricted to the joint fluid in three of them, indicating local production. We conclude that Lyme arthritis is often accompanied by an oligoclonal specific antibody response in joint fluid and serum simultaneously, and occasionally by intrasynovial synthesis of oligoclonal-specific antibodies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3083.1991.tb02492.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Roasted hazelnuts – allergenic activity evaluated by double-blind, placebo-controlled food challenge (2003)
    Oxford, UK : Munksgaard International Publishers
    Allergy 58 (2003), S. 0 
    Details
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background: Allergy to hazelnuts is a common example of birch pollen related food allergy. Symptoms upon ingestion are often confined to the mouth and throat, but severe systemic reactions have been described in some patients. The aim of the study was to evaluate the reduction in allergenicity by roasting of the nuts.Methods: Double-blind, placebo-controlled food challenges (DBPCFC) with roasted hazelnuts (140°C, 40 min) were performed in 17 birch pollen allergic patients with DBPCFC-confirmed food allergy to raw hazelnuts. The effect of roasting was further evaluated by skin prick test (SPT), histamine release (HR), measurement of specific IgE, and IgE-inhibition experiments.Results: In 5/17 patients the DBPCFC with the roasted nuts were positive. The symptoms were generally mild and included OAS (oral allergy syndrome) in all patients. Roasting of the nuts significantly reduced the allergenic activity evaluated by SPT, HR, specific IgE, and IgE-inhibition. Immunoblotting experiments with recombinant hazelnut allergens showed sensitization against Cor a 1.04 in 16/17 patients and against Cor a 2 in 7/17 patients. None of the patients were sensitized to Cor a 8. Challenge-positive patients did not differ from the rest in IgE-binding pattern.Conclusions: All the applied methods indicated that roasting of hazelnuts reduces the allergenicity, but since 5/17 birch pollen allergic patients were DBPCFC-positive to the roasted nuts, ingestion of roasted hazelnuts or products containing roasted hazelnuts can not be considered safe for a number of hazelnut allergic consumers. For patients with a history of severe allergic symptoms upon ingestion of hazelnuts, thorough and conscientious food labelling of hazelnuts and hazelnut residues is essential.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1398-9995.2003.23959.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Intrathecal Synthesis of Anti-Borrelia burgdorferi Antibodies in Neuroborreliosis: a Study with Special Emphasis on Oligoclonal IgM Antibody Bands (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Scandinavian journal of immunology 37 (1993), S. 0 
    Details
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Pre- and post-treatment (up to 3–26 months after antibiotic therapy) humoral immune responses were investigated in five neuroborreliosis patients. Anti-Borrelia (B.) burgdorferi IgG and IgM antibodies in CSF and serum were quantitated by capture ELISA. Agarose gel isoelectric focusing (AIF) and protein blotting were used to detect oligoclonal IgG and IgM bands as well as oligoclonal anti-B. burgdorferi IgG and IgM antibodies. These latter components were visualized by transfer to antigen-coated membranes (immunoblot) and immunoenzymatic staining. By ELISA, intrathecal anti-B. burgdorferi IgG and IgM antibody synthesis was detected in all initial specimens and continued 3–26 months after antibiotic therapy in four and three cases, respectively. AIF with protein blotting showed oligoclonal bands of total IgG as well as total IgM in the initial CSF specimens of all patients and persistence of such components occurred in four and five cases, respectively. By AIF and immunoblot, oligoclonal anti-B. burgdorferi IgG and IgM antibody bands could be detected in the CSF of every patient. IgG antibody bands were present in all initial CSF samples. The first specimen of one patient was negative for IgM antibody bands but such components appeared 3 weeks later. Oligoclonal CSF anti-B. burgdorferi IgG antibody components persisted over the entire follow-up periods in all but one case where they disappeared 6 weeks after treatment. The oligoclonal IgM antibodies in CSF vanished in two cases (after being present up to 4 and 11 months after antibiotic therapy) while they persisted over the entire (3–6 months after antibiotic therapy) follow-up periods in three cases. The specificity of the IgM antibody immunoblot technique was corroborated by control experiments, including antibody absorption studies and use of 41 kDa flagellar antigen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3083.1993.tb02566.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Pulmonary function in adolescents with childhood asthma (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Allergy 48 (1993), S. 0 
    Details
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The aim of this study was to determine the pulmonary function in former and present asthmatics. We examined 77 persons aged 12–24 years, classified into four groups: 1) healthy subjects (controls) (n= 19), 2) former asthmatics (n= 19), 3) present mild asthmatics (n= 20), and 4) present severe asthmatics (n= 19). Although exhibiting no respiratory symptoms, former asthmatics had reduced airflow values measured by FEV, (median (range) 89.7 (83–99) vs 101.4 (91–110)) and MEF25 (76.5 (68–94) vs 103.0 (97–124)), as compared with controls. Furthermore, former asthmatics had significantly increased PEF variability, as compared with controls, whereas no significant differences were found in static lung parameters, i.e. total lung capacity and residual volume, as compared with controls. In conclusion, former asthmatics, although now exhibiting no respiratory symptoms, were found to have obstructive airflow limitation, increased bronchial responsiveness, and normal lung volumes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1398-9995.1993.tb00727.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...