► Wood pyrolysis was characterized in a drop tube reactor at temperatures above 1000 °C. ► Different temperatures and particle sizes were tested. ► No particle effect was observed during the experiments. ► High temperatures favor hydrocarbon destruction and soot formation. ► Char and soot suffer from some changes with a temperature increase. Fast pyrolysis of wood was conducted in a drop tube furnace to study the influence of temperature (1000–1200–1400 °C) and particle size (0.35–0.80 mm) for a particle residence time of some seconds. No effect of particle size has been observed on final pyrolysis products. At 1000 °C, much more gas and tar are produced than char (yield of 96% versus 4%); hydrocarbons, including light species and tar, present a considerable yield of 26%. From 1200 °C, the drastic hydrocarbons decomposition, emphasized with temperature, leads to high yields in soot, H and CO. At 1200 °C, no tar are detected; at 1400 °C only low amounts of CH and C H still remain. Under the explored conditions, char and soot gasification with H O and CO , species produced during pyrolysis, is kinetically blocked. However, even if carbonaceous solids do not seem to be considerably affected by gasification, they suffer some changes when temperature is increased.
OH-equivalent temperatures were derived from all of the temperature profiles retrieved in 2004 and 2005 by the ACE-FTS instrument in a 5 degree band of latitude centred on a ground-based observing station at Maynooth. A globally averaged OH volume emission rate (VER) profile obtained from WINDII data was employed as a weighting function to compute the equivalent temperatures. The annual cycle of temperature thus produced was compared with the annual cycle of temperatures recorded at the ground-based station more than a decade earlier from the OH*(3-1) Meinel band. Both data sets showed excellent agreement in the absolute value of the temperature minimum (similar to 162 K) and in its time of occurrence in the annual cycle at summer solstice. Away from mid-summer, however, the temperatures diverged and reach a maximum disagreement of more than 20 K in mid-winter. Comparison of the Maynooth ground-based data with the corresponding results from two nearby stations in the same time-period indicated that the Maynooth data are consistent with other ground stations. The temperature difference between the satellite and ground-based datasets in winter was reduced to 14-15 K by lowering the peak altitude of the weighting function to 84 km. An unrealistically low peak altitude would be required, however, to bring temperatures derived from the satellite into agreement with the ground-based data. OH equivalent temperatures derived from the SABER instrument using the same weighting function produced results that agreed well with ACE-FTS. When the OH 1.6 mu m VER profile measured by SABER was used as the weighting function, the OH equivalent temperatures increased in winter as expected but the summer temperatures were reduced resulting in an approximately constant offset of 8.6 +/- 0.8 K between ground and satellite values with the ground values higher. Variability in both the altitude and width of the OH layer within a discernable seasonal variation were responsible for the changes introduced. The higher temperatures in winter were due to primarily to the lower altitude of the OH layer, while the colder summer temperatures were due to a thinner summer OH layer. We are not aware of previous reports of the effect of the layer width on ground-based temperatures. Comparison of OH-equivalent temperatures derived from ACE-FTS and SABER temperature profiles with OH*(3-1) temperatures from Wuppertal at 51.3 degrees N which were measured during the same period showed a similar pattern to the Maynooth data from a decade earlier, but the warm offset of the ground values was lower at 4.5 +/- 0.5 K. This discrepancy between temperatures derived from ground-based instruments recording hydroxyl spectra and satellite borne instruments has been observed by other observers. Further work will be required by both the satellite and ground-based communities to identify the exact cause of this difference.
Conventional carbonate–water oxygen isotope thermometry and the more recently developed clumped isotope thermometer have been widely used for the reconstruction of paleotemperatures from a variety of carbonate materials. In spite of a large number of studies, however, there are still large uncertainties in both δ O- and Δ -based temperature calibrations. For this reason there is a need to better understand the controls on isotope fractionation especially on natural carbonates. In this study we analyzed oxygen, carbon and clumped isotopes of a unique set of modern calcitic and aragonitic travertines, tufa and cave deposits from natural springs and wells. Together these samples cover a temperature range from 6 to 95 °C. Travertine samples were collected close to the vents of the springs and from pools, and tufa samples were collected from karstic creeks and a cave. The majority of our vent and pool travertines and tufa samples show a carbonate–water oxygen isotope fractionation comparable to the one of with some samples showing higher fractionations. No significant difference between the calcite–water and aragonite–water oxygen isotope fractionation could be observed. The Δ data from the travertines show a strong relationship with temperature and define the regression Δ = (0.044 ± 0.005 × 10 )/ + (0.205 ± 0.047). The pH of the parent solution, mineralogy and precipitation rate do not appear to significantly affect the Δ -signature of carbonates, compared to the temperature effect and the analytical error. The tufa samples and three biogenic calcites show an excellent fit with the travertine calibration, indicating that this regression can be used for other carbonates as well. This work extends the calibration range of the clumped isotope thermometer to travertine and tufa deposits in the temperature range from 6 °C to 95 °C.
Thermal time models for seed germination assume a continuum of rate responses in the sub-optimal temperature range. Generally, the models describe germination performance in non-dormant seeds at constant temperatures, yetalternating temperature (AT) is a feature of many natural environments. We studied the possible interacting effects of AT on germination progress in photoblastic seeds of three aromatic-medicinal Verbenaceae species in the genera Lippia and Aloysia. For Lippia turbinata f. turbinata and L.turbinata f. magnifolia seed, germination only occurred in light conditions, while for L.integrifolia and Aloysia citriodora it was significantly higher in the light than in darkness. Although relative light germination (RLG) was not different between constant and AT in the sub-optimal range, AT raised the base temperature for germination progress (T-b) from ca. 3-6 degrees C in constant temperature to 7-12 degrees C in AT. Among the species, thermal time for 50% seed germination [(T(50))] was 55-100 degrees Cd at constant temperature. Although AT resulted in slight modifications to (T(50)), the germination rate at comparable average temperatures in the sub-optimal range was slower than under constant temperatures. For all species, the proportion of germinated seeds was similar for constant and AT. Our results suggest that an interaction between cool temperature and darkness during AT treatment limits the temperature range permissive for germination in these positively photoblastic seed, reflecting both close adaptation to the natural ecology and niche requirements of the species.
Multiferroics are potentially future materials in spintronics for memory and data storage applications. In this paper, a series of Li-doped nanoparticles were studied to investigate the effects of Li on the physical properties of the ZnO system. Analysis of structural micrographs and Raman spectra confirmed the wurtzite structure of doped samples. The vibrational modes of Zinc and oxygen atoms were labeled as E-2L and E-2H with an additional mode at 134 cm(-1) in the doped samples. We observed the presence of interstitial and substitutional Li defects from the deconvolution of Li 1s core level spectra using high resolution x-ray photoelectron spectroscopy. The approximated measured values (e.g., for y = 0.04 and 0.08 samples) for interstitial Li defects were 27% and 39%, and for substitutional Li defects were 73% and 61% respectively. For the y = 0.06 composition, dc resistivity was the highest, while the transition temperature (measured from dielectric loss) was the lowest. We observed a non-monotonic trend of saturation magnetization (obtained at 50 K) against the Li concentration. The compositions having the highest magnetic moment were those having higher interstitial Li defects and lower dc resistivity. Higher hole carrier concentrations and dielectric transition temperatures were correlated with the higher magnetization. Interstitial Li defects played a key role in stabilizing more cationic Zn vacancies. Hole carriers were the major cause of long-range ferromagnetic order in these nanoparticles.
The voltammetry for the reduction of oxygen at a microdisk electrode is reported in six commonly used RTILs: [C(4)mim][NTf2], [C(4)mpyrr][NTf2], [C(4)dmim][NTf2], [C(4)mim][BF4], [C(4)mim][PF6], and [N-18.104.22.168][NTf2], where [C(4)mim](+) is 1-butyl-3-methylimidazolium, [NTf2](-) is bis(trifluoromethanesulfonyl)imide, [C(4)mpyrr](+) is N-butyl-N-methylpyrrolidinium, [C(4)dmim](+) is 1-butyl-2,3-methylimidazolium, [BF4](-) is tetrafluoroborate, [PF6](-) is hexafluorophosphate, and [N-22.214.171.124](+) is n-hexyltriethylammonium at varying scan rates (50-4000 mV s(-1)) and temperatures (293-318 K). Diffusion coefficients, D, of oxygen are deduced at each temperature from potential-step chronoamperometry, and diffusional activation energies are calculated. Oxygen solubilities are also reported as a function of temperature. In the six ionic liquids, the Stokes-Einstein relationship (D proportional to eta(-1)) was found to apply only very approximately for oxygen. This is considered in relationship to the behavior of other diverse solutes in RTILs.
The temperature-history method, proposed by Yinping et al, is a simple and economic way to determine the main thermophysical properties of materials used in thermal energy storage based on solid-liquid phase change. It is based on comparing the temperature history of a phase-change material sample and a sample of a well known material upon cooling down. In this paper we describe a further developed evaluation procedure to determine c(p) and h as temperature dependent values which was not the case in Yinping's method, based on the same experimental procedure. Given the suitability of these properties to calculate thermal energy storage using these materials, the method is proposed to present the results obtained in the form of enthalpy-temperature curves. A discussion about the errors produced by this method and an experimental improvement are proposed too.
The paper deals with high-temperature steam oxidation behaviour of Zr1Nb fuel cladding. First of all, comprehensive experimental program was conducted to provide sufficient experimental data, such as the thicknesses of evolved phase layers and the overall weight gain kinetics, as well as the oxygen concentration and nanohardness values at phase boundaries. Afterwards, oxygen diffusion coefficients in the oxide, in the -Zr(O) layer, in the double-phase ( + )-Zr region, and in the -phase region have been estimated based on the experimental data employing analytical solution of the multiphase moving boundary problem, assuming the equilibrium conditions being fulfilled at the interface boundaries. Eventually, the determined oxygen diffusion coefficients served as input into the in-house numerical code, which was designed to predict the high-temperature oxidation behaviour of Zr1Nb fuel cladding. Very good agreement has been achieved between the numerical calculations and the experimental data.
We hypothesized that a targeted temperature of 33 °C as compared to that of 36 °C would increase survival and reduce the severity of circulatory shock in patients with shock on admission after out-of-hospital cardiac arrest (OHCA).The recently published Target Temperature Management trial (TTM-trial) randomized 939 OHCA patients with no difference in outcome between groups and no difference in mortality at the end of the trial in a predefined subgroup of patients with shock at admission. Shock was defined as a systolic blood pressure of 30 min or the need of supportive measures to maintain a blood pressure ≥90 mmHg and/or clinical signs of end-organ hypoperfusion. In this post hoc analysis reported here, we further analyzed the 139 patients with shock at admission; all had been randomized to receive intervention at 33 °C (TTM33; n = 71) or 36 °C (TTM36; n = 68). Primary outcome was 180-day mortality. Secondary outcomes were intensive care unit (ICU) and 30-day mortality, severity of circulatory shock assessed by mean arterial pressure, serum lactate, fluid balance and the extended Sequential Organ Failure assessment (SOFA) score.There was no significance difference between targeted temperature management at 33 °C or 36 °C on 180-day mortality [log-rank test, p = 0.17, hazard ratio 1.33, 95 % confidence interval (CI) 0.88–1.98] or ICU mortality (61 vs. 44 %, p = 0.06; relative risk 1.37, 95 % CI 0.99–1.91). Serum lactate and the extended cardiovascular SOFA score were higher in the TTM33 group (p < 0.01).We found no benefit in survival or severity of circulatory shock with targeted temperature management at 33 °C as compared to 36 °C in patients with shock on admission after OHCA.
The variation in electrical characteristics of Mo/n-InP (1 0 0) Schottky contacts have been systematically investigated as a function of temperature using current–voltage ( – ) and capacitance–voltage ( – ) measurements in the temperature range 200–400 K. The diode parameters like ideality factor and zero-bias barrier height have been found to be strongly temperature dependent and while the zero-bias barrier height ( – ) increases, the ideality factor decreases with increasing temperature. The – characteristics are analyzed on the basis of thermionic emission (TE) theory and the assumption of Gaussian distribution of barrier heights due to barrier inhomogeneities that prevail at the metal–semiconductor interface. The zero-bias barrier height versus 1/2 plot has been drawn to obtain evidence of a Gaussian distribution of the barrier heights and values of and = 144 meV for the mean barrier height and zero-bias standard deviation have been obtained from this plot, respectively. The modified Richardson plot has given mean barrier height and Richardson constant ( **) as 0.85 eV and 2.54 A cm K , respectively. The temperature dependence of the – characteristics of the Mo/n-InP Schottky diode have been successfully explained on the basis of thermionic emission (TE) mechanism with Gaussian distribution of the Schottky barrier heights (SBHs).