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Critical Temperature (critical + temperature)
Selected AbstractsMadelung Strain in Cuprate Superconductors , A Route to Enhancement of the Critical TemperatureADVANCED MATERIALS, Issue 36 2009Vladimir Y. Butko "Madelung Strain" in cuprate films containing metal (M,=,La1.56Sr0.44CuO4) and insulator (I,=,La2CuO4) layers: X-ray diffraction shows that, unexpectedly, the volume of unit cell of the top layer adjusts to that of the bottom layer. The effect is due to long-range Coulomb forces; it affects interfacial superconductivity because the critical temperature scales with the unit-cell height. [source] Latitudinal gradients in diversity: real patterns and random modelsECOGRAPHY, Issue 3 2001Patricia Koleff Mid-domain models have been argued to provide a default explanation for the best known spatial pattern in biodiversity, namely the latitudinal gradient in species richness. These models assume no environmental gradients, but merely a random latitudinal association between the size and placement of the geographic ranges of species. A mid-domain peak in richness is generated because when the latitudinal extents of species in a given taxonomic group are bounded to north and south, perhaps by a physical constraint such as a continental edge or perhaps by a climatic constraint such as a critical temperature or precipitation threshold, then the number of ways in which ranges can be distributed changes systematically between the bounds. In addition, such models make predictions about latitudinal variation in the latitudinal extents of the distributions of species, and in beta diversity (the spatial turnover in species identities). Here we test how well five mid-domain models predict observed latitudinal patterns of species richness, latitudinal extent and beta diversity in two groups of birds, parrots and woodpeckers, across the New World. Whilst both groups exhibit clear gradients in richness and beta diversity and the general trend in species richness is acceptably predicted (but not accurately, unless substantial empirical information is assumed), the fit of these models is uniformly poor for beta diversity and latitudinal range extent. This suggests either that, at least for these data, as presently formulated mid-domain models are too simplistic, or that in practice the mid-domain effect is not significant in determining geographical variation in diversity. [source] Temperature-Responsive Substrates: Adhesion and Mechanical Properties of PNIPAM Microgel Films and Their Potential Use as Switchable Cell Culture Substrates (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 19 2010Mater. Abstract Thermoresponsive poly(N -isopropylacrylamide) (PNIPAM) microgel films are shown to allow controlled detachment of adsorbed cells via temperature stimuli. Cell response occurs on the timescale of several minutes, is reversible, and allows for harvesting of cells in a mild fashion. The fact that microgels are attached non-covalently allows using them on a broad variety of (charged) surfaces and is a major advantage as compared to approaches relying on covalent attachment of active films. In the following, the microgels' physico-chemical parameters in the adsorbed state and their changes upon temperature variation are studied in order to gain a deeper understanding of the involved phenomena. By means of atomic force microscopy (AFM), the water content, mechanical properties, and adhesion forces of the microgel films are studied as a function of temperature. The analysis shows that these properties change drastically when crossing the critical temperature of the polymer film, which is the basis of the fast cell response upon temperature changes. Furthermore, nanoscale mechanical analysis shows that the films posses a nanoscopic gradient in mechanical properties. [source] Adhesion and Mechanical Properties of PNIPAM Microgel Films and Their Potential Use as Switchable Cell Culture SubstratesADVANCED FUNCTIONAL MATERIALS, Issue 19 2010Stephan Schmidt Abstract Thermoresponsive poly(N -isopropylacrylamide) (PNIPAM) microgel films are shown to allow controlled detachment of adsorbed cells via temperature stimuli. Cell response occurs on the timescale of several minutes, is reversible, and allows for harvesting of cells in a mild fashion. The fact that microgels are attached non-covalently allows using them on a broad variety of (charged) surfaces and is a major advantage as compared to approaches relying on covalent attachment of active films. In the following, the microgels' physico-chemical parameters in the adsorbed state and their changes upon temperature variation are studied in order to gain a deeper understanding of the involved phenomena. By means of atomic force microscopy (AFM), the water content, mechanical properties, and adhesion forces of the microgel films are studied as a function of temperature. The analysis shows that these properties change drastically when crossing the critical temperature of the polymer film, which is the basis of the fast cell response upon temperature changes. Furthermore, nanoscale mechanical analysis shows that the films posses a nanoscopic gradient in mechanical properties. [source] Thermal performance of juvenile Atlantic Salmon, Salmo salar L.FUNCTIONAL ECOLOGY, Issue 6 2001B. JONSSON Summary 1,Experimental data for maximum growth and food consumption of Atlantic Salmon (Salmo salar L.) parr from five Norwegian rivers situated between 59 and 70°N were analysed and modelled. The growth and feeding models were also applied to groups of Atlantic Salmon growing and feeding at rates below the maximum. The data were fitted to the Ratkowsky model, originally developed for bacterial growth. 2,The rates of growth and food consumption varied significantly among populations but the variation appeared unrelated to thermal conditions in the river of population origins. No correlation was found between the thermal conditions and limits for growth, thermal growth optima or maximum growth, and hypotheses of population-specific thermal adaptation were not supported. Estimated optimum temperatures for growth were between 16 and 20 °C. 3, Model parameter estimates differed among growth-groups in that maximum growth and the performance breadth decreased from fast to slow growing individuals. The optimum temperature for growth did not change with growth rate. 4, The model for food consumption (expressed in energy terms) peaked at 19,21 °C, which is only slightly higher than the optimal temperature for growth. Growth appeared directly related to food consumption. Consumption was initiated ,2 °C below the lower temperature for growth and terminated ,1·5 °C above the upper critical temperature for growth. Model parameter estimates for consumption differed among growth-groups in a manner similar to the growth models. 5,By combining the growth and consumption models, growth efficiencies were estimated. The maximum efficiencies were high, 42,58%, and higher in rivers offering hostile than benign feeding and growth opportunities. [source] A highly sensitive thermosensing CMOS Circuit Based on self-biasing circuit techniqueIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 2 2009Tetsuya Hirose Non-memebr Abstract A thermosensing CMOS circuit that changes its internal voltage steeply at a critical temperature was developed. The circuit is based on a self-biasing circuit technique and uses the temperature-sensitive characteristics of MOSFETs operating in the subthreshold region. To develop this sensor device, a method to analyze self-biasing circuits, which is different from a conventional one, was employed. This method is useful for understanding the self-biasing circuit operation. A temperature sensor device makes use of a MOSFET resistor's transition from a strong inversion to a weak-inversion or subthreshold operation. The temperature at which the transition occurs can be set to a desired value by adjusting the parameters of MOSFETs in the circuit. The sensor LSI can be made using a standard CMOS process and can be used as over-temperature and over-current protectors for LSI circuits. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] Modelling of hygro-thermal behaviour and damage of concrete at temperature above the critical point of waterINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 6 2002D. Gawin Abstract In this paper, a model for the analysis of the behaviour of concrete at temperature largely exceeding critical point of water, is presented. In this temperature range liquid phase, i.e. capillary phase, and gas phase cannot be distinguished and only the latter exists. Consequently, capillary pressure has no more physical meaning above this point and liquid water is present only as physically adsorbed water. In this work, we give a different physical interpretation to the capillary pressure and use it still for the description of the hygrometric state of concrete in the zone, where temperature exceeds the critical point of water. Considerable thermal dilatation of the liquid water and the real behaviour of water vapour close to critical temperature are taken into account. Moreover, a special switching procedure in order to avoid the Stefan-like problem, which subsequently arises, is described and employed in the calculations. Finally, several numerical examples demonstrating the robustness of the adopted solution have been shown. Copyright © 2002 John Wiley & Sons, Ltd. [source] Determination of cubic equation of state parameters for pure fluids from first principle solvation calculationsAICHE JOURNAL, Issue 8 2008Chieh-Ming Hsieh Abstract A new method for estimation of parameters in cubic equations of state from ab initio solvation calculations is presented. In this method, the temperature-dependent interaction parameter a(T) is determined from the attractive component of solvation free energy, whereas the volume parameter b is assumed to be that of solvation cavity. This method requires only element-specific parameters, i.e., atomic radius and dispersion coefficient, and nine universal parameters for electrostatic and hydrogen-bonding interactions. The equations of state (EOS) parameters so determined allow the description of the complete fluid phase diagram, including the critical point. We have examined this method using the Peng,Robinson EOS for 392 compounds and achieved an accuracy of 43% in vapor pressure, 17% in liquid density, 5.4% in critical temperature, 11% in critical pressure, and 4% in critical volume. This method is, in principle, applicable to any chemical species and is especially useful for those whose experimental data are not available. © 2008 American Institute of Chemical Engineers AIChE J, 2008 [source] Critical behavior in quenched random structures: Mean-field lattice-gas approachAICHE JOURNAL, Issue 2 2001S. De A new mean-field equation-of-state model is proposed for predicting the critical behavior of fluids confined in porous, random structures. The approach is based on a lattice-gas formalism and incorporates effects of both fluid confinement and energetically heterogeneous interactions between fluid molecules and pore surfaces. The model was used to predict a variety of thermodynamic properties in these systems, including the dependence of the confined fluid's critical properties on the porosity and relative strength of fluid,fluid and fluid,pore interaction energies. The study of suface-energy heterogeneities show that they significantly affect the critical temperature of the confined fluid, at a given porosity, compared to the uniform energy case. Comparison of the model performance with both grand canonical Monte Carlo simulation results and a set of adsorption data in a silica gel suggest that the approach taken here provides a useful analytic method for calculating physical properties in complex systems of this kind. [source] Freeze-dry microscopy of protein/sugar mixtures: Drying behavior, interpretation of collapse temperatures and a comparison to corresponding glass transition DataJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 9 2009Eva Meister Abstract The purpose of this study is to investigate the change in collapse appearance and temperature of protein/sugar mixtures as a function of nucleation temperature (Tn), sublimation velocity (Vsub) and the sugar/protein mole ratio when performing freeze-dry microscopy experiments. BSA and HSA were used as sample proteins and mixed with either sucrose or trehalose. Differential scanning calorimetry was used to determine the corresponding glass transition temperatures . To allow a more representative comparison between these analytical methods, a collapse midpoint temperature (Tc-50) was introduced. While there was no distinct correlation between Tn and the onset of collapse (Toc) for either mixture, Vsub was found to correlate with the measured collapse temperature which is important for comparability of experiments. Furthermore, Vsub could be used to qualitatively investigate the product resistance to water vapor flow. A dramatic change in the appearance of collapse was found for high sugar/protein mole ratios (,362:1) which needs to be considered to avoid a misinterpretation of Toc data. At low protein concentrations midpoint data showed good agreement with Toc values but were found significantly lower at higher protein concentrations. Application of the Gordon,Taylor equation failed to predict the critical temperature for any of the protein/sugar mixtures studied. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:3072,3087, 2009 [source] Multivariate chemometric approach to thermal solid-state FT-IR monitoring of pharmaceutical drug compoundJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 8 2008Wei Jian Tan Abstract The study of thermal-related solid-state reaction monitored by spectroscopic method needs the use of advanced multivariate chemometric approach. It is because visual inspection of spectral data on particular functional groups or spectral bands is difficult to reveal the complete physical and chemical information. The spectral contributions from various species involved in the solid-state changes are generally highly overlapping and the spectral differences between reactant and product are usually quite minute. In this article, we demonstrate the use of multivariate chemometric approach to resolve the in situ thermal-dependent Fourier-transform infrared (FT-IR) mixture spectra of lisinopril dihydrate when it was heated from 24 to 170°C. The collected FT-IR mixture spectra were first subjected to singular value decomposition (SVD) to obtain the right singular vectors. The right singular vectors were rotated into a set of pure component spectral estimates based on entropy minimization and spectral dissimilarity objective functions. The resulting pure component spectral estimates were then further refined using alternating least squares (ALS). In current study, four pure component spectra, that is, lisinopril dihydrate, monohydrate, anhydrate, and diketopiperazine (DKP) were all resolved and the relative thermal-dependent contributions of each component were also obtained. These relative contributions revealed the critical temperature for each transformation and degradation. This novel approach provides better interpretation of the pathway of dehydration and intramolecular cyclization of lisinopril dihydrate in the solid state. In addition, it can be used to complement the information obtained from differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97: 3379,3387, 2008 [source] Micelle-to-vesicle transition induced by oligonucleotide in SDS/DEAB mixed system with a net negative chargeJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2008Xia Guo Abstract Sodium dodecyl sulfate (SDS)/dodecyl triethyl ammonium bromide (DEAB) mixed micelles (with SDS in excess) can transform to vesicles only when the temperature is higher than a critical value. In this study, we report for the first time that oligonucleotide can decrease the critical temperature to a much lower value and, hence, induce micelle-to-vesicle transition. The facilitation efficiency of oligonucleotide on vesicle formation is closely dependent on its size and base composition. Moreover, the SDS/DEAB/oligonucleotide vesicles are negatively charged and the hydrophobic interaction between oligonucleotide and SDS/DEAB mixed micelles is the driving force. As, so far, the report about the facilitation effect of oligonucleotide and DNA on vesicle formation is very limited, this study may provide some helpful information for the application of DNA/amphiphile system. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7491,7504, 2008 [source] Cooperative scattering of light and atoms in ultracold atomic gasesLASER PHYSICS LETTERS, Issue 7 2008H. Uys Abstract Superradiance and coherent atomic recoil lasing are two closely related phenomena, both resulting from the cooperative scattering of light by atoms. In ultracold atomic gases below the critical temperature for Bose-Einstein condensation these processes take place with the simultaneous amplification of the atomic matter waves. We explore these phenomena by surveying some of the experimental and theoretical developments that have emerged in this field of study since the first observation of superradiant scattering from a Bose-Einstein condensate in 1999 [1]. (© 2008 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Global regular solutions to Cahn,Hilliard system coupled with viscoelasticityMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 17 2009Irena Paw Abstract In this paper we prove the existence and uniqueness of a global in time, regular solution to the Cahn,Hilliard system coupled with viscoelasticity. The system arises as a model, regularized by a viscous damping, of phase separation process in a binary deformable alloy quenched below a critical temperature. The key tools in the analysis are estimates of absorbing type with the property of exponentially time-decreasing contribution of the initial data. Such estimates allow not only to prolong the solution step by step on the infinite time interval but also to conclude the existence of an absorbing set. Copyright © 2009 John Wiley & Sons, Ltd. [source] Infinitely many stationary solutions for a simple climate model via a shooting methodMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 4 2002J. I. Díaz Abstract In this paper, we study the number of steady solutions of a non-linear model arising in Climatology. By applying a shooting method we show the existence of infinitely many steady solutions for some values of a parameter (the solar constant). This method allows us to determine how many times a solution attains the critical temperature (,10°C) at which the coalbedo is assumed to be discontinuous. Copyright © 2002 John Wiley & Sons, Ltd. [source] Data quality in thermal summation development models for forensically important blowfliesMEDICAL AND VETERINARY ENTOMOLOGY, Issue 3 2009C. S. RICHARDS Abstract. To highlight some issues regarding data quality that are significant in estimating post-mortem intervals (PMI) from maggots, the developmental constants of thermal summation models for development of Chrysomya megacephala Fabricius (Diptera: Calliphoridae) were calculated from incidental data gathered from 12 published studies, and from data generated specifically for the purpose in a single experiment. The focused experiment involved measuring the timing of five developmental landmarks at nine constant temperatures with a sampling resolution of 6,12 h, which is characteristic of other published studies. Combining data from different studies produced inconsistent results because of statistical noise introduced by (at least) disparities in temporal precision, descriptive statistics, geographical location and rearing diets. A robust experimental design to estimate a developmental model should involve at least six constant temperatures, starting at about 7°C above the relevant developmental zero (D0) and going almost to the upper critical temperature, and a temporal sampling interval with a relative precision of about 10%, which requires sampling about every 2 h until hatching, about every 3 h until first ecdysis and about every 6 h until second ecdysis. [source] The Effect of Decreasing Temperature up to Chilling Values on the in vivo F685/F735 Chlorophyll Fluorescence Ratio in Phaseolus vulgaris and Pisum sativum: The Role of the Photosystem I Contribution to the 735 nm Fluorescence Band ,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2000Giovanni Agati ABSTRACT The effect of leaf temperature (T), between 23 and 4°C, on the chlorophyll (Chl) fluorescence spectral shape was investigated under moderate (200 ,E m,2 s,1) and low (30,35 ,E m,2 s,1) light intensities in Phaseolus vulgaris and Pisum sativum. With decreasing temperature, an increase in the fluorescence yield at both 685 and 735 nm was observed. A marked change occurred at the longer emission band resulting in a decrease in the Chl fluorescence ratio, F685/F735, with reducing T. Our fluorescence analysis suggests that this effect is due to a temperature-induced state 1,state 2 transition that decreases and increases photosystem II (PSII) and photosystem I (PSI) fluorescence, respectively. Time-resolved fluorescence lifetime measurements support this interpretation. At a critical temperature (about 6°C) and low light intensity a sudden decrease in fluorescence intensity was observed, with a larger effect at 685 than at 735 nm. This is probably linked to a modification of the thylakoid membranes, induced by chilling temperatures, which can alter the spillover from PSII to PSI. The contribution of photosystem I to the long-wavelength Chl fluorescence band (735 nm) at room temperature was estimated by both time-resolved fluorescence lifetime and fluorescence yield measurements at 685 and 735 nm. We found that PSI contributes to the 735 nm fluorescence for about 40, 10 and 35% at the minimal (F0), maximal (Fm) and steady-state (Fs) levels, respectively. Therefore, PSI must be taken into account in the analysis of Chl fluorescence parameters that include the 735 nm band and to interpret the changes in the Chl fluorescence ratio that can be induced by different agents. [source] Feshbach shape resonance for high Tc superconductivity in superlattices of nanotubesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2006Antonio Bianconi Abstract The case of a Feshbach shape resonance in the pairing mechanism for high Tc superconductivity in a crystalline lattice of doped metallic nanotubes is described. The superlattice of doped metallic nanotubes provides a superconductor with a strongly asymmetric gap. The disparity and different spatial locations of the wave functions of electrons in different subbands at the Fermi level should suppress the single electron impurity interband scattering giving multiband superconductivity in the clean limit. The Feshbach resonances will arise from the component single-particle wave functions out of which the electron pair wave function is constructed: pairs of wave functions which are time inverse of each other. The Feshbach shape resonance increases the critical temperature by tuning the chemical potential at the Lifshitz electronic topological transition (ETT) where the Fermi surface of one of the bands changes from the one dimensional (1D) to the two dimensional (2D) topology (1D/2D ETT). (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Molecular dynamics simulation of annihilation of 60° dislocations in Si crystalsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 2 2009Qingyuan Meng Abstract The annihilation of two 60° shuffle dislocations is studied via the molecular dynamics method. The Stillinger,Weber (SW) potential and environment-dependent interatomic potential (EDIP) are used to describe the atomic interactions. The simulation results show that the complete annihilation of the 60° dislocations takes place only when the two dislocations lie on the same slip plane. The annihilation process may occur without external shear stress when the temperature is higher than a critical value. It is found that the critical temperature increases exponentially as a function of distance between the two dislocations. Also revealed in this simulation is an incomplete annihilation occurring when the distance between the slip planes of the two dislocations is less than about 1 nm. If the distance between the two slip planes is larger than about 1 nm, the dislocations will glide on their own slip planes as if no interaction exists between them. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Phase diagram of a thin Heisenberg antiferromagnetic filmPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 9 2007J. Cabral Neto Abstract We investigate the thickness dependence of the Néel temperature of a thin quantum spin-1/2 Heisenberg antiferromagnetic film as a function of the magnetic field on a simple cubic lattice. The Néel temperature TN(H, ,) is obtained by using the framework of the effective-field theory for films consisting of , = 2, 3, 5, 10 and , (bulk) interacting layers. We present the phase diagram of T versus H in the whole range of the magnetic field for several values of ,. A continuous phase-transition line separating the antiferromagnetic and ferromagnetic phases is observed. The critical temperature TN(H, ,) of the film is smaller than the corresponding bulk critical temperature (H) , TN(H, ,) of the infinite system, which has been analyzed recently by Bublitz Filho and de Sousa [Phys. Lett. A 323, 9 (2004)]; as , is increased, TN(H, ,) also increases and approaches (H) for large values of ,. We have, also, studied the quantum phase transition where three critical fields were found: Hc(,) = 6.224 for , , 3 (three-dimensional regime), Hc(, = 2) = 5.210 (intermediate regime) for , = 2 and, finally, the two-dimensional regime at , = 1 with Hc(, = 1) = 4.194. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effects of Zn doping on YBaCuO superconductorPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 9 2006M. Mahtali Abstract In this work we present a study of Zn impurity effects on the YBa2Cu3O7,, high Tc superconducting ceramics prepared by the solid state reaction method. X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential thermal analysis (DTA) techniques, and resistivity measurements are used to characterize the YBa(Cu1,xZnx)3O7,, samples. The obtained results show that, for example, the value of the transition critical temperature is decreasing up to 80 K caused by the substitution of Zn for Cu in the interval 0 , x , 0.01. Also, the peritectic transformation of superconducting phase undergoes a displacement to lower temperatures compared with pure YBaCuO. On the basis of the obtained results, the effects of Zn doping on the structural and electronic properties are explained. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Transport in MgB2 near critical temperaturePHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 9 2006P. Va Abstract Longitudinal and transverse voltages have been studied on samples of MgB2. The non-zero transverse voltage has been observed in close vicinity of critical temperature in zero external magnetic field while far enough from Tc this voltage has been zero. It merges into transverse even voltage in magnetic field which is suppressed with increasing field and increasing transport current as well. New scaling between transverse and longitudinal resistivities has been observed in the form ,xy , d,xx/dT. Several models trying to explain observed results are discussed. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Microwave detection using Josephson junction arrays integrated in a resonatorPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 5 2005Oleksandr M. Ivanyuta Abstract The possibilities and physical mechanisms of detection of microwave X- and Ka-band radiation by high-temperature superconducting (HTS) YBa2Cu3O7-0.05 (YBCO) bicrystalline Josephson junctions (JJ) embedded in a surface wave resonator (SWR) are considered. Microwave detection was investigated experimentally by using a linear Josephson junction array (JJA) embedded in the SWR. Measurements were carried out starting from the critical temperature of HTS film (T = 92 K), down to the liquid nitrogen level (T = 77 K) and beyond (down to 20 K) using the Gifford-McMahon closed-cycle cryo-cooler. The sensitivity of such type of detectors was determined to be approximately 104 V/W. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Growth in elevated CO2 protects photosynthesis against high-temperature damagePLANT CELL & ENVIRONMENT, Issue 6 2000Daniel R. Taub ABSTRACT We present evidence that plant growth at elevated atmospheric CO2 increases the high-temperature tolerance of photosynthesis in a wide variety of plant species under both greenhouse and field conditions. We grew plants at ambient CO2 (~ 360 ,mol mol,1) and elevated CO2 (550,1000 ,mol mol,1) in three separate growth facilities, including the Nevada Desert Free-Air Carbon Dioxide Enrichment (FACE) facility. Excised leaves from both the ambient and elevated CO2 treatments were exposed to temperatures ranging from 28 to 48 °C. In more than half the species examined (4 of 7, 3 of 5, and 3 of 5 species in the three facilities), leaves from elevated CO2 -grown plants maintained PSII efficiency (Fv/Fm) to significantly higher temperatures than ambient-grown leaves. This enhanced PSII thermotolerance was found in both woody and herbaceous species and in both monocots and dicots. Detailed experiments conducted with Cucumis sativus showed that the greater Fv/Fm in elevated versus ambient CO2 -grown leaves following heat stress was due to both a higher Fm and a lower Fo, and that Fv/Fm differences between elevated and ambient CO2 -grown leaves persisted for at least 20 h following heat shock. Cucumis sativus leaves from elevated CO2 -grown plants had a critical temperature for the rapid rise in Fo that averaged 2·9 °C higher than leaves from ambient CO2 -grown plants, and maintained a higher maximal rate of net CO2 assimilation following heat shock. Given that photosynthesis is considered to be the physiological process most sensitive to high-temperature damage and that rising atmospheric CO2 content will drive temperature increases in many already stressful environments, this CO2 -induced increase in plant high-temperature tolerance may have a substantial impact on both the productivity and distribution of many plant species in the 21st century. [source] Evaporation of solvent molecules by ultrafast heating: effect on conformation of solvated proteinRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 3 2010Saravana Prakash Thirumuruganandham Using molecular dynamics simulation, we compare two cases of ultrafast heating of a small water droplet containing a solvated protein (echistatin). If the water temperature after irradiation is above the critical temperature, explosive boiling liberates the protein within some 10,ps of its hydration shell, while its temperature remains relatively low. By comparing with the case where the water shell is heated to the same final temperature, but without complete evaporation, we demonstrate that the protein conformation is governed by the hydration shell rather than by the protein temperature. Copyright © 2010 John Wiley & Sons, Ltd. [source] Resting energy metabolism of Goeldi's monkey (Callimico goeldii) is similar to that of Other callitrichidsAMERICAN JOURNAL OF PRIMATOLOGY, Issue 2 2003Michael L. Power Abstract The resting metabolic rates (RMRs) of six adult Goeldi's monkeys (Callimico goeldii) were measured using standard methods of open circuit respirometry during both the active (daytime) and inactive (nighttime) circadian phases for this species. One subject was measured both while she was pregnant and after she delivered a full-term, stillborn infant. Inactive-phase RMR within thermal neutrality (above 27.5°C) averaged 288.5±30.8 ml O2/hr; active-phase RMR within thermal neutrality averaged 416.3±60.9 ml O2/hr. These values are 74.6% and 107.6%, respectively, of the mammalian expected for animals of this body mass. During the inactive phase, metabolic rate increased an estimated 4.3% for every degree decline in temperature below 27.5°C. The RMR in Goeldi's monkey is similar quantitatively and qualitatively to those of other captive callitrichids that have been studied, with active-phase RMR being at or slightly above the mammalian expected, and inactive-phase RMR being significantly reduced. We propose that this circadian pattern of RMR is a consequence of small body size, and is not a specific metabolic adaptation within the Callitrichidae. Thus we predict that metabolic studies measuring both circadian phases in other small primates will also find this pattern of reduced RMR during the inactive phase. The inactive-phase RMR within thermal neutrality of the pregnant female was not different from that measured after the stillbirth, despite an almost 15% difference in body mass. During pregnancy, however, the female was more metabolically responsive to temperature below thermal neutrality, and had a lower upper critical temperature (i.e., was less tolerant of heat). Am. J. Primatol. 60:57,67, 2003. © 2003 Wiley-Liss, Inc. [source] Functional renormalization group approach to the BCS-BEC crossoverANNALEN DER PHYSIK, Issue 9 2010S. Diehl Abstract The phase transition to superfluidity and the BCS-BEC crossover for an ultracold gas of fermionic atoms is discussed within a functional renormalization group approach. Non-perturbative flow equations, based on an exact renormalization group equation, describe the scale dependence of the flowing or average action. They interpolate continuously from the microphysics at atomic or molecular distance scales to the macroscopic physics at much larger length scales, as given by the interparticle distance, the correlation length, or the size of the experimental probe. We discuss the phase diagram as a function of the scattering length and the temperature and compute the gap, the correlation length and the scattering length for molecules. Close to the critical temperature, we find the expected universal behavior. Our approach allows for a description of the few-body physics (scattering and molecular binding) and the many-body physics within the same formalism. [source] Low-frequency line temperatures of the CMB (Cosmic Microwave Background)ANNALEN DER PHYSIK, Issue 9 2009R. Hofmann Abstract Based on SU(2) Yang-Mills thermodynamics we interprete Aracde2's and the results of earlier radio-surveys on low-frequency cosmic microwave background (CMB) line temperatures as a phase-boundary effect. We explain the excess at low frequencies by evanescent, nonthermal photon fields of the CMB whose intensity is nulled by that of Planck distributed calibrator photons. The CMB baseline temperature thus is identified with the critical temperature of the deconfining-preconfining transition. [source] Quantum phase diagram for homogeneous Bose-Einstein condensateANNALEN DER PHYSIK, Issue 4 2005H. Kleinert Abstract We calculate the quantum phase transition for a homogeneous Bose gas in the plane of s -wave scattering length as and temperature T. This is done by improving a one-loop result near the interaction-free Bose-Einstein critical temperature Tc(0) with the help of recent high-loop results on the shift of the critical temperature due to a weak atomic repulsion based on variational perturbation theory. The quantum phase diagram shows a nose above Tc(0), so that we predict the existence of a reentrant transition above Tc(0), where an increasing repulsion leads to the formation of a condensate. [source] Oscillations of the critical temperature in superconducting Nb/Ni bilayersANNALEN DER PHYSIK, Issue 1-2 2003A.S. Sidorenko Abstract We investigated Nb/Ni bilayers prepared by magnetron sputtering on glass subtrates. The quality of the films was characterized by small-angle X-ray diffraction analysis. The thickness of the layers was determined by the Rutherford backscattering spectrometry (RBS). For specimens with constant Nb layer thickness we observed distinct oscillations of the superconducting critical temperature upon increasing the thickness of the Ni layer. The results are interpreted in terms of Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) like inhomogeneous superconducting pairing in the ferromagnetic Ni Layer. [source] | |||||||||||||||||||||||||