Search Results - (Author, Cooperation:Rieß)

Rieß, Werner [Hrsg.]; Wirtz, Markus; Barzel, Bärbel; Schulz, Andreas

Unknown

413 S. : graph. Darst.

9783830926870

German

Berthe-Corti, Luise; Rieß, Falk

Unknown

64 S. : Ill., graph. Darst.

1. Aufl.

3922850170

Materialien für den Unterricht

German

Rieß, Werner

Unknown

464 S.

978-3-8309-2311-4, 9783830923114

Internationale Hochschulschriften

German

1618-2650

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Electronic Resource

0935-9648

Chemistry ; Polymer and Materials Science

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Physics

2 Ill.

Electronic Resource

2019-08-28

Sociology & anthropology ; Soziologie, Anthropologie ; Industrie- und Betriebssoziologie, Arbeitssoziologie, industrielle Beziehungen ; Sociology of Work, Industrial Sociology, Industrial Relations ; Globalisierung ; Wettbewerb ; Produktion ; Flexibilität ; Vernetzung ; Unternehmen ; Reorganisation ; Outsourcing ; Lean Management ; Kraftfahrzeugindustrie ; Zulieferer ; Arbeitsbeziehungen ; Arbeitszeit ; Arbeitsorganisation ; Qualifikationsanforderungen ; Arbeitsbedingungen ; Mitbestimmung ; Interessenvertretung ; globalization ; competition ; production ; flexibility ; networking ; enterprise ; reorganization ; outsourcing ; lean management ; automobile industry ; subcontractor ; labor relations ; working hours ; work organization ; qualification requirements ; working conditions ; codetermination ; representation of interests

Sammelwerksbeitrag, collection article

1089-7550

AIP Digital Archive

Physics

The thermal electromotive force (EMF) generated across a specimen owing to a small nonuniformity in the sample's temperature is used to follow phase transitions in the specimen. As the temperature is scanned, a first-order phase transition yields a sharp S-shaped peak in the EMF versus time, t, and temperature, T(t), curves. A transition to a superconducting state exhibits a sharp drop in EMF as was observed during measurements on YBa2Cu3O7. The dependence of the EMF on time and temperature is calculated for a first-order phase transition. Predictions are confirmed by experiment. This method is therefore useful for detecting phase transition temperatures. A practical feature of this measurement is the ability to precisely calibrate, in situ, the temperature measuring element, e.g., thermometer or thermocouple, when the transition temperature is already known.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

Current-voltage relations on circular samples with four equally spaced semicircle electrodes are investigated both theoretically and experimentally. An expression is given for the dependence of the two-point resistance on the electrode size, sample radius, and thickness. Combining this with a four-point van der Pauw conductivity measurement enables the determination of the electrode overpotential. Experimental results of the I-V relations in a thin carbon layer are presented.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

An approach giving a physical understanding of the stress-induced leakage current (SILC) generation kinetics based on anode hole injection and hole dispersive transport in the oxide is presented. It is shown that the SILC is not directly correlated to the defects responsible for oxide breakdown. However, it is suggested that trapped holes can impact on the defect creation rate and, in turn, on the breakdown generation. © 2000 American Institute of Physics.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

Transient electroluminescence (EL) from single- and multilayer organic light-emitting diodes (OLEDs) was investigated by driving the devices with short, rectangular voltage pulses. The single-layer devices consist of indium-tin oxide (ITO)/tris(8-hydroxy-quinoline)aluminum (Alq3)/magnesium (Mg):silver (Ag), whereas the structure of the multilayer OLEDs are ITO/copper phthalocyanine (CuPc)/N,N′-di(naphthalene-1-yl)-N,N′-diphenyl-benzidine (NPB)/Alq3/Mg:Ag. Apparent model-dependent values of the electron mobility (μe) in Alq3 have been calculated from the onset of EL for both device structures upon invoking different internal electric field distributions. For the single-layer OLEDs, transient experiments with different dc bias voltages indicated that the EL delay time is determined by the accumulation of charge carriers inside the device rather than by transport of the latter. This interpretation is supported by the observation of delayed EL after the voltage pulse is turned off. In the multilayer OLED the EL onset—dependent on the electric field—is governed by accumulated charges (holes) at the internal organic-organic interface (NPB/Alq3) or is transport limited. Time-of-flight measurements on 150-nm-thin Alq3 layers yield weak field-dependent μe values of the order of 1×10−5 cm2/Vs at electrical fields between 3.9×105 and 1.3×106 V/cm. © 2001 American Institute of Physics.

Electronic Resource

1551-2916

Blackwell Publishing Journal Backfiles 1879-2005

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Physics

Using solid materials prepared by melting or sintering allows inert metal electrodes to be embedded inside the solid. The I–V relations for four linear electrodes embedded inside a rectangular sample are evaluated. Two cases are considered: (a) a sample with uniform electronic (electron/hole) conductivity and (b) the electron/hole partial current in a sample that is a mixed ionic-electronic conductor with a nonuniform electron/hole distribution. Equations are derived which allow the determination of the conductivity from four-electrode measurements if a pure electronic conductor is considered or if a mixed ionic-electronic conductor is considered with the ionic current being blocked.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

Detailed investigations of the device characteristics of poly-p-phenylene-vinylene (PPV) light-emitting diodes are reported. We analyze the influence of various hole- and electron-injecting electrodes on the current–voltage (I–V) characteristics and electroluminescence behavior. Our studies reveal that thermal conversion of the prepolymer on indium–tin–oxide (ITO) substrates leads—in contrast to conversion on Au and other high-work-function metals—to a p-type doping of PPV and, additionally, to the formation of an ohmic hole-injecting contact at the ITO/PPV interface. Hence, devices fabricated with low-work-function metals acting as the electron injecting contact (for example, Al and Ca) display Schottky behavior. These Schottky diodes are distinguished by a high rectification ratio ρr of about 106 and display electroluminescence at bias voltages as low as 1.5 V for ITO/PPV/Ca light-emitting diodes. The I–V characteristics can be quantitatively described within the modified Shockley equation, taking into account the voltage drop on a serial resistance, yielding ideality factors n ranging from 1.6 to 2.4 for different devices. At high current densities, space-charge-limited currents determine the device characteristics. The hole mobility μh is found to be of the order of 10−5 cm2/V s. © 1997 American Institute of Physics.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

Polymer electrochemical cells with ion blocking electrodes were reported to emit light under applied voltage. This work analyzes the current-voltage relations, internal electric fields, and point defect distribution in the polymer. The polymer is regarded as a mixed-ionic-electronic conductor. Two relevant defect models are investigated. A good fit is obtained between experimental data and theory which also takes into consideration electrode overpotentials. © 1997 American Institute of Physics.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

Electrical impedance measurements on poly-p-phenylene-vinylene (PPV) light-emitting diodes in the frequency range between 100 Hz and 10 MHz are reported. A significant difference can be revealed between the device characteristics of light-emitting diodes eliminated on indium-tin-oxide (ITO) and those of other high-work-function metals (e.g., Au). Thermal conversion of the precursor polymer on ITO substrates results in a p-type doping of the conjugated polymer PPV. Hence, devices in the configuration ITO/PPV/Al display Schottky behavior, which can be modeled by a simple equivalent circuit of two RC elements in series, representing a bulk and a junction region. The low-frequency device capacitance displays a pronounced voltage dependence and, from a detailed analysis, the ionized acceptor concentration NA, the diffusion potential VD, and the width of the space charge region w can be obtained. Typical values for NA are 1016–1017 cm−3, and for VD within the range 1–1.5 V, resulting in a width w of the space charge region at zero bias of about 50–150 nm. Via temperature-dependent investigations a transition from a p-type semiconductor Schottky diode at room temperature to a metal/insulator(polymer)/metal structure at lower temperatures is revealed. © 1997 American Institute of Physics.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

The chemical potential of oxygen in nonstoichiometric ceria, CeO2−x, was measured versus composition x (10−4 ≤x ≤10−2) and temperature (823≤T≤1073 K) using a novel solid electrochemical cell, utilizing yttrium stabilized zirconia. The composition of CeO2−x was varied by coulometric titration. The O2 chemical potential was determined from the electromotive force of the cell with air used as the reference gas. With this new experimental setup, it is possible to carry out long coulometric titrations at very low oxygen partial pressures (limited by 10−30 atm at 823 K or by 10−13 atm at 1473 K). For x between 10−4 and 10−2, the O2 partial pressure in equilibrium with CeO2−x was found to change from 10−8 to 10−18 atm at 1073 K and from 10−16 to 10−30 atm at 823 K. The oxygen vacancies in CeO2−x were determined to be V‘0 in this (x,T) range. The charge on aliovalent cations impurities was found to dominate the negative (effective) charge concentration for x(approximately-less-than)10−3. The oxygen partial molar enthalpy ΔH¯(O2) is 870 kJ/mol (9 eV) for x(approximately-greater-than)3×10−3 decreasing for smaller x to a value of 670 kJ/mol (7 eV) for x=10−4.

Electronic Resource

1471-4159

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Electronic Resource

1471-4159

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Huntington's disease (HD) is an autosomal dominantly inherited progressive neurodegenerative disorder caused by a CAG/polyglutamine repeat expansion in the gene encoding the huntingtin protein. We have recently generated a rat model transgenic for HD, which displays a slowly progressive phenotype resembling the human adult-onset type of disease. In this study we systematically assessed the distribution and density of 17 transmitter receptors in the brains of 2-year-old rats using quantitative multi-tracer autoradiography and high-resolution positron emission tomography. Heterozygous animals expressed increased densities of M2 acetylcholine (increase of 148 ± 16% of controls; p 〉 0.001; n = 7), nicotine (increase of 149 ± 16% of controls; p 〉 0.01; n = 6), and α2 noradrenergic receptors (increase of 141 ± 15% of controls; p 〉 0.001; n = 6), respectively. Densities of these receptors were decreased in homozygous animals. Decreases of receptor density in both hetero- and homozygous animals were found for M1 acetylcholine, 5-HT2A serotonin, A2A adenosine, D1 and D2 dopamine, and GABAA receptors, respectively. Other investigated receptor systems showed small changes or were not affected. The present data suggest that the moderate increase of CAG/polyglutamine repeat expansions in the present rat model of Huntington's disease is characterized by subtype-selective and region-specific changes of neuroreceptor densities. In particular, there is evidence for a contribution of predominantly presynaptically localized cholinergic and noradrenergic receptors in the response to Huntington's disease pathology.

Electronic Resource

1468-2958

Blackwell Publishing Journal Backfiles 1879-2005

Media Resources and Communication Sciences, Journalism

Attitude statements present a particular image of the respondent to onlookers and can be tactically used for self-presentational purposes. The present study investigated the relationship between variables relevant to self-presentation and attitude statements following proattitudinal actions. Under conditions of high or low decision freedom, female subjects committed themselves to argue for a proattitudinal issue. The experimenter described the issue as either low or high in importance, and subsequent attitudes toward the issue were measured in a way which allowed low (subjects did not sign their questionnaires and placed them in a collection box) or high (subjects signed their questionnaires and handed them to the experimenter) personal association with attitude statements. A triple interaction of the variables was found on subjects'statements of personal involvement with the issue. As suggested by a self-presentation approach, subjects expressed more involvement under no-choice/low-association/high-importance conditions than under choice/low-association/high-importance conditions. Subjects who were denied personal responsibility and close association with an important action apparently increased their involvement to gain responsibility. The findings failed to support self-perception predictions of more favorable attitudes under choice rather than no-choice conditions.

Electronic Resource

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

Two new methods for operating a time-of-flight mass spectrometer are suggested. The first is a beam compression method which allows separation of one kind of particle (one m/q ratio) at a time, from a beam continously emitted by an ion source. Due to the continuous operation of the source a corresponding increase in signal-to-noise ratio is expected. The second method is based on forming a multiplex beam by modulating a continuously emitted ion beam. The use of a time array detector enables the collection of the data. The algorithm of analysis is presented. This method should have the increased throughput advantage. An improvement in signal-to-noise ratio need not take place.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

Partial pressure gradients due to temperature gradients in a mixture of reactive gases, limit the possible use of sensors. Problems arise when a partial pressure sensor is subjected to a temperature, different from that of the sample. A model is proposed that allows the calculation of the partial pressure distributions in a temperature gradient. Experiments conducted using O2, H2, and H2O in Ar confirm the predictions. It is shown how to relate the sensor's reading to the parameter of interest. It is also concluded that in certain cases it is advisable to deliberately add a reactive gas, as this facilitates the interpretation of the measurements.

Electronic Resource