Hole burning in YSZ:Pr3+ and YSZ:Eu3+ with various Y2O3 concentration

We have measured the hole spectra in YSZ:Pr³⁺ and YSZ:Eu³⁺ with various Y₂O₃ concentrations at low temperature. The temperature dependence of the hole width which obtained from the hole spectra in YSZ:Pr³⁺ and YSZ:Eu³⁺ was similar to that for disordered materials.

However, the Y₂O₃ concentration dependence of the hole width in YSZ:Pr³⁺ was contrary to that for YSZ:Eu³⁺ at low temperature. The hole width was the widest in the case of YSZ:Pr³⁺ at 10 mol% Y₂O₃. On the contrary, it was the narrowest in the case of YSZ:Eu³⁺ at the same concentration of Y₂O₃. It was found that there are two states in YSZ, in which the degree of ordered differs from each other. Additionally, the Y₂O₃ concentration dependence of the hole width at low temperature has reflected the ionic conductivity of YSZ at high temperature. It is suggested that the ordering of local structure is responsible for the ionic conduction in YSZ.

© 2003 Elsevier Science Ltd. All rights reserved.     

Performance evaluation of a heat pump cycle using NARMs by a simulation with equations of heat transfer and pressure drop

Simulation analyses for a vapour compression heat pump cycle using nonazeotropic refrigerant mixtures (NARMs) of R22 and R114 are conducted under the condition that the heat pump thermal output and the flow rate and inlet temperatures of the heat sink and source water are given. The heat transfer coefficients of the condensation and evaporation are calculated with empirical correlations proposed by the authors. The validity of the evaluation method and the correlations is demonstrated by comparison with experimental data. The relations between the coefficient of performance (COP) and composition are shown under two conditions: (1) the constant heat transfer length of the condenser and evaporator; and (2) the constant temperature of refrigerant at the heat exchanger inlet. The COP of the NARMs is higher than that of pure refrigerant when the heat transfer lengths of the condenser and evaporator are sufficiently long.     

A new characterization method of the microstructure using the macroscopic composition gradient in alloys

A new experimental method to determine the phase boundary and phase equilibria is accomplished by using the transmission electron microscopic observation of alloys having the macroscopic composition gradient. The various phase boundaries,i.e., the coherent binodal and spinodal lines and incoherent binodal line, are distinctly determined for the Cu-Ti alloy system. Furthermore, the equilibrium compositions at the interface of precipitate/matrix are experimentally obtained for various particle sizes, and therefore, the Gibbs-Thomson relation is verified. It is expected that the composition gradient method proposed in the present study will become an important experimental method for microstructural characterization.     

Increases in the mitochondrial DNA replication and transcription in the remnant liver of rats

A phase I study to determine safety, maximum tolerated dose, and biologic response during multiple once-a-week administration of oral imiquimod, an immune response modifier, was conducted in 12 adults with early human immunodeficiency virus (HIV) infection. All completed the dose-escalation phase of weekly dosing at 100-mg increments and received at least one maintenance dose, 100 mg below the patient's toxic dose, for 12 weeks. Dose-limiting toxicity occurred in 3 patients at 200-mg, 5 at 300-mg, and 3 at 400-mg dose levels. One tolerated the 500-mg dose without dose-limiting toxicity. Dose-limiting toxicities included fatigue, fever, malaise, increased transaminases, hypotension, vomiting, and depression. Seven of 12 completed 12 weeks of maintenance. At > or = 200 mg of imiquimod, all patients had biologic responses, measured by elevations in serum interferon, beta2-microglobulin, and neopterin levels. Imiquimod induced pronounced levels of circulating interferon in asymptomatic HIV-infected persons, with variable effect on virus load.     

A possible neurophysiological basis for psychological pain

There is some evidence that the anterior cingulate cortex (ACC) contains nociceptive neurons, and other neurons which respond to conditioned aversive stimuli. It is not implausible that nociceptive input and conditioned aversive input converge onto common neurons in the ACC. Following from this hypothesis, the psychological pain which occurs in circumstances that arouse disgust or aversion may involve the same mechanisms that give rise to referred pain.     

Electromagnetic analysis coupled with motion for high‐speed circuit breakers of eddy current repulsion using the tableau approach

Electromagnetic field analysis coupled with motion using the tableau approach has been applied to high‐speed circuit breakers of eddy current repulsion mechanisms. This breaker has an opening time of 1 ms and break time less than 1 cycle (20 ms). The driving part of the breaker is composed of electromagnetic repulsion mechanisms and disk springs with nonlinear characteristics. The mechanisms are composed of two fixed coils and one repulsion plate. A numeric experiment has been applied to investigate the dynamic behavior of the electromagnetic repulsion mechanism using the equivalent circuit method. Calculation results were in good agreement with both measurement results and calculation results by FEM on an experimental model. In addition, repulsive forces depending on material conductivities have been researched. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 152(4): 8–16, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20149     

Noise characteristics of GaInNAsSb 1300-nm-range VCSEL with optical feedback for isolator-free module

The behavior of relative intensity noise of GaInNAsSb 1300-nm-range vertical-cavity surface-emitting lasers (VCSELs) is presented for the first time. The relative intensity noise drastically increases beyond a critical optical feedback. It was theoretically and experimentally found that the increase of relaxation oscillation frequencies was effective for the sensitivity of the optical feedback in the single-mode long-wavelength VCSELs. In our experiment, the critical feedback levels were -32 and -29 dB when frequencies were 4.0 and 5.8 GHz. This result is in good agreement with a theory.     

Effect of mechanical stress induced by etch-stop nitride: impact on deep-submicron transistor performance

This paper reports that process-induced mechanical stress affects the performance of short-channel MOSFETs, and focuses on the effect of a plasma-enhanced CVD nitride contact-etch-stop layer. The stress in the channel region induced by the nitride layer changes transconductance (G_m), thereby changing the device performance. When the nitride stress varies from +300 MPa (tensile) to −1.4 GPa (compressive), NMOSFET performance degrades by up to 8% and PMOSFET performance improves up to 7%. These changes are caused by the modulation of the electron/hole mobilities, so controlling process-induced stress and considering this mobility change in a precise transistor model are necessary for deep-submicron transistor design.