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Measurement Temperatures (measurement + temperature)
Selected AbstractsAnalysis and selection criteria of BSIM4 flicker noise simulation modelsINTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 7 2008T. Noulis Abstract CMOS transistors' noise performance is mainly dominated by flicker (1/f) noise. BSIM4.X MOSFET simulation model develops two distinct models, SPICE-Flicker and BSIM-Flicker, to calculate flicker noise. In this paper, these two models are analytically examined and compared to noise measurements, using an NMOS and a PMOS device fabricated in 0.6µm process by Austria Mikro Systeme (AMS). MOSFET 1/f noise measurements and the respective simulations were obtained under various bias conditions, as to study which flicker noise model is the optimum in each operating region. Measurement temperature was constant at 295,K. Comparisons suggest that in an NMOS transistor operating in the triode or saturation region, BSIM-Flicker model is accurate and therefore preferable. In a PMOS transistor, the most suitable model to describe its 1/f noise performance in the linear regime is also BSIM-Flicker, whereas SPICE-Flicker is more preferable in saturation. In NMOS transistors, the selected model provides a great accurate description of flicker noise, contrary to PMOS transistors, where simulation models appear to be quite unreliable and need further improvement. Copyright © 2007 John Wiley & Sons, Ltd. [source] High-temperature stability of Au/p-type diamond Schottky diodePHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 6 2009Tokuyuki Teraji Abstract Rectification properties of Au Schottky diodes were investigated in high-temperature operation. These diodes were fabricated on a p-type diamond single crystal using the vacuum-ultraviolet light/ozone treatment. The ideality factor n of the Schottky diodes decreased monotonically with increasing measurement temperature whereas the Schottky barrier height ,b increased, and ,b reached 2.6 eV at 550 K with n of 1.1. Through high temperature heating at 870 K, the mean value of ,b at 300 K changed permanently from 2.2 eV to 1.1 eV. Decrease of ,b might originate from a dissolution of oxygen termination at the Au/diamond interface. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The effect of temperature on C4 -type leaf photosynthesis parametersPLANT CELL & ENVIRONMENT, Issue 9 2007RAIA-SILVIA MASSAD ABSTRACT C4 -type photosynthesis is known to vary with growth and measurement temperatures. In an attempt to quantify its variability with measurement temperature, the photosynthetic parameters , the maximum catalytic rate of the enzyme ribulose 1·5-bisphosphate carboxylase/oxygenase (Rubisco) (Vcmax), the maximum catalytic rate of the enzyme phosphoenolpyruvate carboxylase (PEPC) (Vpmax) and the maximum electron transport rate (Jmax) , were examined. Maize plants were grown in climatic-controlled phytotrons, and the curves of net photosynthesis (An) versus intercellular air space CO2 concentrations (Ci), and An versus photosynthetic photon flux density (PPFD) were determined over a temperature range of 15,40 °C. Values of Vcmax, Vpmax and Jmax were computed by inversion of the von Caemmerer & Furbank photosynthesis model. Values of Vpmax and Jmax obtained at 25 °C conform to values found in the literature. Parameters for an Arrhenius equation that best fits the calculated values of Vcmax, Vpmax and Jmax are then proposed. These parameters should be further tested with C4 plants for validation. Other model key parameters such as the mesophyll cell conductance to CO2 (gi), the bundle sheath cells conductance to CO2 (gbs) and Michaelis,Menten constants for CO2 and O2 (Kc, Kp and Ko) also vary with temperature and should be better parameterized. [source] An Efficient Way to Assemble ZnS Nanobelts as Ultraviolet-Light Sensors with Enhanced Photocurrent and StabilityADVANCED FUNCTIONAL MATERIALS, Issue 3 2010Xiaosheng Fang Abstract Although there has been significant progress in the fabrication and performance optimization of one-dimensional nanostructure-based photodetectors, it is still a challenge to develop an effective and low-cost device with high performance characteristics, such as a high photocurrent/dark-current ratio, photocurrent stability, and fast time response. Herein an efficient and low-cost method to achieve high-performance ,visible-blind' microscale ZnS nanobelt-based ultraviolet (UV)-light sensors without using a lithography technique, by increasing the nanobelt surface areas exposed to light, is reported. The devices exhibit about 750 times enhancement of a photocurrent compared with individual nanobelt-based sensors and an ultrafast time response. The photocurrent stability and time response to UV-light do not change significantly when a channel distance is altered from 2 to 100,µm or the sensor environment changes from air to vacuum and different measurement temperatures (60 and 150,°C). The photoelectrical behaviors can be recovered well after returning the measurement conditions to air and room temperature again. The low cost and high performance of the resultant ZnS nanobelt photodetectors guarantee their highest potential for visible-blind UV-light sensors working in the UV-A band. [source] ESR studies on superparamagnetic Fe3O4 nanoparticlesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2004Y. Köseo Abstract In this study we have investigated temperature and frequency dependence of magnetic properties of superparamagnetic iron oxide nanoparticles (SPION). ESR measurements have been carried out in a temperature range of 10,300 K. A single, relatively broad and temperature dependent EPR signal was observed at all measurement temperatures. The linewidth slightly increases with decreasing temperature down to 100 K, then it sharply increases down to 60 K. Below 60 K the trend is reversed and the linewidth start to decrease. The resonance field remains almost constant down to 100 K and decreases sharply as the temperature is decreased further. The resonance field of the ESR spectra of Fe3O4 shows a linear dependence on microwave frequency. By using experimental results, the effective g-value and internal field are deduced as 1.9846 and ,40 G, respectively. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The temperature response of photosynthesis in tobacco with reduced amounts of RubiscoPLANT CELL & ENVIRONMENT, Issue 4 2008DAVID S. KUBIEN ABSTRACT The reasons for the decline in net CO2 assimilation (A) above its thermal optimum are controversial. We tested the hypothesis that increasing the ratio of Rubisco activase to Rubisco catalytic site concentration would increase the activation state of Rubisco at high temperatures. We measured photosynthetic gas exchange, in vivo electron transport (J) and the activation state of Rubisco between 15 and 45 °C, at 38 and 76 Pa ambient CO2, in wild-type (WT) and anti- rbcS tobacco. The Rubisco content of the anti- rbcS lines was 30% (S7-1) or 6% (S7-2) of WT, but activase levels were the same in the three genotypes. Anti- rbcS plants had lower A than WT at all temperatures, but had a similar thermal optimum for photosynthesis as WT at both CO2 levels. In WT plants, Rubisco was fully activated at 32 °C, but the activation state declined to 64% at 42 °C. By contrast, the activation state of Rubisco was above 90% in the S7-1 line, between 15 and 42 °C. Both A and J declined about 20% from Topt to the highest measurement temperatures in WT and the S7-1 line, but this was fully reversed after a 20 min recovery at 35 °C. At 76 Pa CO2, predicted rates of RuBP regeneration-limited photosynthesis corresponded with measured A in WT tobacco at all temperatures, and in S7-1 tobacco above 40 °C. Our observations are consistent with the hypothesis that the high temperature decline in A in the WT is because of an RuBP regeneration limitation, rather than the capacity of Rubisco activase to maintain high Rubisco activation state. [source] The effect of temperature on C4 -type leaf photosynthesis parametersPLANT CELL & ENVIRONMENT, Issue 9 2007RAIA-SILVIA MASSAD ABSTRACT C4 -type photosynthesis is known to vary with growth and measurement temperatures. In an attempt to quantify its variability with measurement temperature, the photosynthetic parameters , the maximum catalytic rate of the enzyme ribulose 1·5-bisphosphate carboxylase/oxygenase (Rubisco) (Vcmax), the maximum catalytic rate of the enzyme phosphoenolpyruvate carboxylase (PEPC) (Vpmax) and the maximum electron transport rate (Jmax) , were examined. Maize plants were grown in climatic-controlled phytotrons, and the curves of net photosynthesis (An) versus intercellular air space CO2 concentrations (Ci), and An versus photosynthetic photon flux density (PPFD) were determined over a temperature range of 15,40 °C. Values of Vcmax, Vpmax and Jmax were computed by inversion of the von Caemmerer & Furbank photosynthesis model. Values of Vpmax and Jmax obtained at 25 °C conform to values found in the literature. Parameters for an Arrhenius equation that best fits the calculated values of Vcmax, Vpmax and Jmax are then proposed. These parameters should be further tested with C4 plants for validation. Other model key parameters such as the mesophyll cell conductance to CO2 (gi), the bundle sheath cells conductance to CO2 (gbs) and Michaelis,Menten constants for CO2 and O2 (Kc, Kp and Ko) also vary with temperature and should be better parameterized. [source] Dynamic photo-inhibition and carbon gain in a C4 and a C3 grass native to high latitudesPLANT CELL & ENVIRONMENT, Issue 11 2004D. S. KUBIEN ABSTRACT C4 plants are rare in the cool climates characteristic of high latitudes and altitudes, perhaps because of an enhanced susceptibility to photo-inhibition at low temperatures relative to C3 species. In the present study we tested the hypothesis that low-temperature photo-inhibition is more detrimental to carbon gain in the C4 grass Muhlenbergia glomerata than the C3 species Calamogrostis Canadensis. These grasses occur together in boreal fens in northern Canada. Plants were grown under cool (14/10 °C day/night) and warm (26/22 °C) temperatures before measurement of the light responses of photosynthesis and chlorophyll fluorescence at different temperatures. Cool growth temperatures led to reduced rates of photosynthesis in M. glomerata at all measurement temperatures, but had a smaller effect on the C3 species. In both species the amount of xanthophyll cycle pigments increased when plants were grown at 14/10 °C, and in M. glomerata the xanthophyll epoxidation state was greatly reduced. The detrimental effect of low growth temperature on photosynthesis in M. glomerata was almost completely reversed by a 24-h exposure to the warm-temperature regime. These data indicate that reversible dynamic photo-inhibition is a strategy by which C4 species may tolerate cool climates and overcome the Rubisco limitation that is prevalent at low temperatures in C4 plants. [source] |