Use of maximum temperature for correction of alanine dosimetry in electron beams

Alanine dosimetry is well characterized for irradiation temperature response. In use, alanine absorbed dose response is corrected for the irradiation temperature. The temperature used to correct alanine dosimetry absorbed dose response in electron beams has historically been the mean temperature occurring during irradiation (Sharpe and Miller, 2009). At lower absorbed doses, the change in temperature is relatively low; thus the absorbed dose response correction due to temperature is small. However, industrial electron beam processing often requires higher absorbed dose measurements where the change in temperature can be very large and the corresponding dose response correction for alanine becomes significant. This paper compares the impact of the temperature correction based on the use of a mean irradiation temperature (Sharpe and Miller, 2009) versus the use of a maximum irradiation temperature on the absorbed dose measurement. The results of this comparison indicate that the use of a mean temperature correction for higher absorbed doses measured with temperature corrected alanine dosimetry introduces a bias in the absorbed dose estimate.     

The gas temperature in and the gas expulsion from a graphite furnace used for atomic absorption spectrometry

A simplified model for heat transfer based on thermal conduction is used to calculate the radial gas temperature distribution inside a semi-enclosed, commercial graphite tube furnace used for atomic absorption spectrometry. In the absence of a forced convective flow of a purge gas, the gas temperature inside the graphite furnace during its heating is lower than the wall temperature. After the wall temperature has attained a steady-state value, the gas temperature approaches the wall temperature and the radial temperature gradient in the gas decreases. The difference between the wall temperature and the gas temperature depends on the temperature program used, the thermal properties of the purge gas, and the atomizer geometry. The residence time of relatively volatile analyte elements is largely controlled by expulsion when wall atomization at high heating rates and high atomization temperatures are used. Analytical sensitivities are often enhanced by vaporizing the analyte into a gas having an approximately constant temperature.     

Control of the electrode temperature for electrochemical studies: A new approach illustrated on porous anodizing of aluminium

A new approach for studying the effect of temperature on electrochemical processes is presented in this paper. Using an in-house developed electrode holder, experiments are performed under conditions of applied and controlled electrode temperature. This new approach provides an improved temperature control during the experimental study and, additionally, allows distinguishing both the influences of the electrolyte and electrode temperatures. The advantages of the applied electrode temperature approach are illustrated by considering porous anodizing of aluminium. In a broad temperature range the electrochemical behaviour of the aluminium electrodes, recorded during the new and the conventional way of anodizing, are compared. Differences between the anodic potential evolutions in both approaches are observed, and are explained by a heat flux to the surroundings during the experiments at uncontrolled electrode temperature. These results illustrate the advantage of applying the electrode temperature. If the influence of temperature on a process is investigated by merely varying the electrolyte temperature, the electrode temperature is only indirectly influenced and can significantly differ from the electrolyte temperature. Therefore, when evaluating the influence of temperature on an electrochemical system the electrode temperature should be considered, and preferentially also controlled.     

Temperature characterization analysis of LiFePO<Subscript>4</Subscript>/C power battery during charging and discharging

In order to study the surface temperature change and distribution during charging and discharging and in the simulation working condition of LiFePO₄/C power battery at normal temperature, the surface temperature is tested by placing the battery in the incubator and fixing 10 temperature probes on the battery surface. Results show that the temperature of the upper part is higher, and the temperature at the bottom is the lowest, while around the positive electrode is the highest during charging and discharging. The maximum temperature rising rate is reached at the moment of constant current charging transforming to the constant voltage charging during charging, and at the end moment during discharging. During charging in a certain range and discharging, the relations between the maximum temperature, the average temperature rising rate, and the maximum temperature difference of all the measurement points at the same time and the current are approximately linear, respectively. In the simulation working condition, the moment of the maximum temperature is consistent with the large current discharging instantaneous in each stage.     

Minimizing Temperature Bias through Reliable Temperature Determination in Gas-Solid Photothermal Catalytic Reactions

Enormous advances in photothermal catalysis have been made over the years, whereas the temperature assessment still remains controversial in the majority of photothermal catalytic systems. Herein, we methodically uncovered the phenomenon of temperature determination bias arising from prominent temperature differences in gas-solid photothermal catalytic systems, which extensively existed yet has been overlooked in most relevant cases. To avoid the interference of temperature bias, we developed a universal protocol for reliable temperature evaluation of gas-solid photothermal catalytic reactions, with emphasis on eliminating the temperature gradient and temperature fluctuation of catalyst layer via optimizing the reaction system. This work presents a functional and credible practice for temperature detection, calling attention to addressing the effects of temperature differences, and reassessing the actual temperature-based performances in gas-solid photothermal catalysis.     

Thermally-regulated molecular selectivity of organosilica sol-gels

The feasibility of using temperature as a control mechanism for altering the selectivity of organosilica sol-gels for a specific molecule is demonstrated in this communication. The porous organosilica sol-gels act as reversible thermoresponsive materials which become hydrophobic at higher temperature and hydrophilic at lower temperature. When exposed to a mixture of molecules, the gels selectively intake the more hydrophobic species at higher temperature. A particularly remarkable feature of these gels is their ability to preferentially sequester the hydrophobic molecule at high temperature and the hydrophilic species at low temperature. Finally, these gels selectively intake hydrophobic molecules at high temperature and then preferentially release them when the temperature is lowered.     

BN掺杂钛酸钡基NTC材料的研究

钛酸钡基材料在居里温度以下呈优异的NTC特性,围绕BN掺杂制备钛酸钡基NTC功能陶瓷材料,分别对不同掺杂量、烧结工艺过程进行了研究.结果表明,随着烧结温度的升高,NTC材料的致密化程度增强,其室温电阻率和NTC效应也会有一些变化,随着烧结温度的提高,NTC材料的居里温度也会有微小的变化;加入BN采用传统固相烧结法在烧结...     

Thermal characteristics of gelatin extracted from shaari fish skin

Gelatin extraction yield increased with the increase of acetic acid concentration and temperature. Gelatin extracted from shaari skin using 0.1 N acid solutions and temperatures of 323 and 353 K gave highest protein content comparable to that of commercial bovine and porcine gelatins. In general, gelatin extracted from shaari gelatin showed lower onset of glass transition temperature than mammalian gelatins. For shaari skin gelatin, the onset of glass transition temperature decreased with the increase of extraction temperature up to 323 K and then remained nearly constant. The decrease in glass transition was more pronounced for gelatin extracted at 0.01 N compared to the 0.1 and 1.0 N samples. Unfolding temperature decreased exponentially with the increase of extraction temperature. The unfolding temperature shifted to lower temperature, and the decrease was more pronounced in the case of higher (1.0 N) concentrated samples. The extraction concentration and temperature did not show significant effect on the onset solids-melting temperature.     

磁性碳化硅陶瓷先驱体聚铁碳硅烷的研究

通过低分子量的聚硅烷与二茂铁反应合成了聚铁碳硅烷(PFCS).探索了反应温度、裂解温度、二茂铁含量等因素对合成PFCS的影响.元素分析、红外光谱、氢谱分析表明,铁被引入到PFCS中,PFCS与聚碳硅烷的结构相似.高温裂解聚铁碳硅烷所得碳化硅陶瓷具有一定的磁性.     

The size of particle aggregates produced by flocculation with PNIPAM, as a function of temperature

This work investigates the effect of temperature on the size of alumina aggregates formed by flocculation with temperature responsive Poly(N-Isopropylacrylamide)(PNIPAM). The results are discussed in terms of the effects of temperature on particle collision, particle adhesion and aggregate breakage. It was found that the size of alumina aggregates increases with increasing solution temperature. Particle/particle collision and aggregate breakage are largely unaffected by increasing solution temperature and therefore could not account for the change in aggregate size. The dominant factor in aggregate growth with increasing temperature was found to be the increase in the force of adhesion between alumina particles. The appearance of the adhesive force is triggered by the increase in temperature above the lower critical solution temperature of PNIPAM.     

油剂混合区的工艺条件对催化裂化汽油改质的影响

利用连续式小型提升管催化裂化实验装置研究了原料预热温度、再生剂温度、油剂混合区温度和剂油比等油剂混合区的工艺条件对催化裂化汽油改质的影响规律。结果表明,降低再生剂温度、油剂混合区温度和剂油比均可以降低干气和焦炭的产率,同时也对催化裂化汽油改质的效果产生了影响。其中,再生剂温度对干气和焦炭产率影响最大;剂油比对催化裂化汽油改质的效果影响显著。降低再生剂温度、剂油比和油剂混合区温度一定程度上降低了烯烃转化率、异构烷烃增加率和芳烃增加率。提高原料预热温度可以一定程度上增加烯烃转化率、异构烷烃增加率和芳烃增加率。催化裂化汽油改质油剂混合区的最佳工艺条件为维持一定的反应温度和剂油比,并尽可能降低再生剂温度和提高原料预热温度。     

Effects of temperature and flow regulated carbon dioxide cooling in longitudinally modulated cryogenic systems for comprehensive two-dimensional gas chromatography

Two different modes of temperature regulation in longitudinally modulated cryogenic systems (LMCSs) for comprehensive two-dimensional gas chromatography (GC x GC) were compared. Carbon dioxide was used as coolant. In the first mode of operation, the temperature of the trap was regulated to pre-set temperature using a digital temperature controller ("the constant temperature mode"). In the second, the temperature was regulated to a fixed negative offset to the oven temperature by using a constant flow of CO2 ("the constant flow mode"). A number of problems were occasionally observed using the constant temperature mode: (1) severe band broadening of high boiling analytes in the second dimension; (2) non-Gaussian reconstructed first-dimension peak profiles; (3) high background due to modulation of first-dimension column bleed. It was concluded that these problems were associated with inefficient solute remobilization at low LMCS trap temperatures (1 and 2) or large trap temperature fluctuations (3). These problems could be avoided or significantly reduced by using the constant flow mode. Best results were obtained as the trap temperature was kept about 70 degrees C below the oven temperature.     

指数升温脱附研究

本文采用分子筛吸附苯或正已烷, 进行指数程序升温脱附。结果表明, 活化能与脱附最大速率所对应的温度(T_m)有线性关系, 即E_d=KT_m。对指数升温条件下得到的脱附图谱与各个脱附动力学参量之间的关系进行了数学分析, 并将分析结果与线性升温所得的结果相比较。各对应的动力学参数的数值基本相同。我们推导得到的指数升温基本方程与目前通用的线性升温基本方程~[2]相比较, 如果温度的测量精度相同则指数升温计算方法的精度比线性升温高(2T+△T)倍。实验还说明, 指数升温的曲线比线性升温容易控制。     

Connecting SiO4 in Silicate and Silicate Chain Networks to Compute Kulli Temperature Indices

A topological index is a numerical parameter that is derived mathematically from a graph structure. In chemical graph theory, these indices are used to quantify the chemical properties of chemical compounds. We compute the first and second temperature, hyper temperature indices, the sum connectivity temperature index, the product connectivity temperature index, the reciprocal product connectivity temperature index and the F temperature index of a molecular graph silicate network and silicate chain network. Furthermore, a QSPR study of the key topological indices is provided, and it is demonstrated that these topological indices are substantially linked with the physicochemical features of COVID-19 medicines. This theoretical method to find the temperature indices may help chemists and others in the pharmaceutical industry forecast the properties of silicate networks and silicate chain networks before trying.     

A temperature window for the synthesis of single-walled carbon nanotubes by catalytic chemical vapor deposition of CH4 over Mo-Fe/MgO catalyst

A temperature window of single-walled carbon nanotubes (SWCNTs) growth has been studied by Raman spectroscopy. The results presented when temperature lower than 750 degrees C, there were few SWCNTs formed, and when temperature higher than 900 degrees C, mass amorphous carbons were formed in the SWCNTs bundles due to the self-decomposition of CH4. The temperature window of SWCNTs efficiently growth is between 800 and 900 degrees C, and the optimum growth temperature is about 850 degrees C. These results were supported by transmission electron microscope images of samples formed under different temperature. The temperature window is important for large-scale production of SWCNTs by catalytic chemical vapor deposition method.     

Modelling the thermal behaviour of the low-thermal mass liquid chromatography system

We report upon the experimental investigation of the heat transfer in low thermal mass LC (LTMLC) systems, used under temperature gradient conditions. The influence of the temperature ramp, the capillary dimensions, the material selection and the chromatographic conditions on the radial temperature gradients formed when applying a temperature ramp were investigated by a numerical model and verified with experimental temperature measurements. It was found that the radial temperature gradients scale linearly with the heating rate, quadratically with the radius of the capillary and inversely to the thermal diffusivity. Because of the thermal radial gradients in the liquid zone inside the capillary lead to radial viscosity and velocity gradients, they form an additional source of dispersion for the solutes. For a temperature ramp of 1 K/s and a strong temperature dependence of the retention of small molecules, the model predicts that narrow-bore columns (i.d. 2.1 mm) can be used. For a temperature ramp of 10 K/s, the maximal inner diameter is of the order of 1 mm before a substantial increase in dispersion occurs.     

Climate change, global warming and coral reefs: modelling the effects of temperature

Climate change and global warming have severe consequences for the survival of scleractinian (reef-building) corals and their associated ecosystems. This review summarizes recent literature on the influence of temperature on coral growth, coral bleaching, and modelling the effects of high temperature on corals. Satellite-based sea surface temperature (SST) and coral bleaching information available on the internet is an important tool in monitoring and modelling coral responses to temperature. Within the narrow temperature range for coral growth, corals can respond to rate of temperature change as well as to temperature per se. We need to continue to develop models of how non-steady-state processes such as global warming and climate change will affect coral reefs.     

聚合物熔体冷却阶段结晶行为的多尺度模拟

针对结晶型聚合物熔体冷却过程的结晶行为,建立了偶合宏观温度场与微观结晶形态的多尺度模型.该模型揭示了宏观温度的变化会引起晶核数、晶体生长速率的改变,从而影响微观结晶形态;而微观结晶释放的潜热也将导致宏观温度的改变.为了求解上述多尺度模型,提出了有限体积/像素法偶合的多尺度算法,即在粗网格上采用有限体积法对宏观温度场进行求解,而在细网格上采用像素法对微观结晶形态进行模拟.基于多尺度模型及多尺度算法,文中对二维聚合物熔体模壁等速降温的冷却问题进行了研究,考察了温度、相对结晶度的变化及结晶形态的演化,并比较了不同冷却速率、初始温度对温度、相对结晶度及结晶形态的影响.数值结果表明,冷却速率是影响结晶行为的关键.高冷却速率下,温度平台出现较早,持续较短;结晶过程对应的温度范围较广;且平均晶体直径较小.而初始温度只影响温度平台及结晶行为出现的早晚,与其持续时间几乎无关。     

Synthesis of Segmented Silica Rods by Regulation of the Growth Temperature

The control of the diameter of colloidal structures is of fundamental interest and practical importance. We synthesized segmented silica rods by regulating the reaction temperature while the rods were growing. With higher growth temperatures, the segment diameter became smaller. Longer incubation times gave longer segments at the same temperature. Similarly, high temperature for the same incubation time gave longer segments. It appears that the correlation between temperature and diameter results from the relation between temperature and the size of the emulsion droplet, that is, the higher the temperature, the smaller the emulsion droplet.     

How hot? Systematic convergence of the replica exchange method using multiple reservoirs

We have devised a systematic approach to converge a replica exchange molecular dynamics simulation by dividing the full temperature range into a series of higher temperature reservoirs and a finite number of lower temperature subreplicas. A defined highest temperature reservoir of equilibrium conformations is used to help converge a lower but still hot temperature subreplica, which in turn serves as the high‐temperature reservoir for the next set of lower temperature subreplicas. The process is continued until an optimal temperature reservoir is reached to converge the simulation at the target temperature. This gradual convergence of subreplicas allows for better and faster convergence at the temperature of interest and all intermediate temperatures for thermodynamic analysis, as well as optimizing the use of multiple processors. We illustrate the overall effectiveness of our multiple reservoir replica exchange strategy by comparing sampling and computational efficiency with respect to replica exchange, as well as comparing methods when converging the structural ensemble of the disordered Aβ_21‐30 peptide simulated with explicit water by comparing calculated Rotating Overhauser Effect Spectroscopy intensities to experimentally measured values. © 2009 Wiley Periodicals, Inc. J Comput Chem 31: 620–627, 2010