Narrow Results

The optical and thermodynamic properties of aluminum oxide (Al₂O₃) were investigated through the density functional theory. In this paper, to examine the structural parameters the GGA-PBEsol potential was used. The Becke–Johnson (TB-mBJ) potential was applied to estimate the optical properties, and the Gibbs2 code was used to examine the thermodynamic behavior of Al₂O₃. The optical analysis shows that the optical properties were improved and the spectrum red-shifted occurs under high pressure. The thermodynamics behavior of the Al₂O₃ in temperatures ranging from 0K to 1400K and the pressure ranging from 0GPa to 60GPa were achieved using the quasi-harmonic Debye model to elucidate the relationships between thermodynamic parameters and temperature under variant pressure. The results show that the optical and thermodynamic properties of Al₂O₃ are significantly improved under high pressure. This enhancement suggests that Al₂O₃ could be used more effectively in many industrial applications, including high-performance ceramics, thermal barrier coatings and as an optical material in devices such as lasers and sensors. In addition, the findings provide important insights into the behavior of Al₂O₃ compounds under high-pressure environments, which could enhance material design procedures for advanced technologies.

We have used the molecular-dynamic method for the calculation of the structural, dynamic and elastic properties of group BeS, BeSe and BeTe compounds for temperature ranging from 300 to 1200 K. Tersoff potential has been used to model the interaction between the groups II–VI compound atoms. The structural properties of cubic BeS, BeSe and BeTe have been calculated, and good agreement between the calculated and experimental values have been found. We have also predicted the elastic constants and diffusion coefficients of BeS, BeSe and BeTe. The values found compare very well with the theoretical results. For the temperature range under study, all elastic constants and dynamic properties show a softening with increasing temperature very similar to the theoretical calculations.

We studied numerically the influences of damping and temperature of medium on the properties of the soliton transported bio-energy in the α-helix protein molecules with three channels by using the dynamic equations in the improved Davydov theory and fourth-order Runge–Kutta method. From the simulation experiments, we see that the new solitons can move along the molecular chains without dispersion at a constant speed, in which the shape and energy of the soliton can remain in the cases of motion, whether short-time at T=0 or long time at T=300 K. In these motions, the soliton can travel over about 700 amino acid residues, thus its lifetime is, at least, 120 ps at 300 K. When the two solitons undergo a collision, they can also retain themselves forms to transport towards. These results are consistent with the analytic result obtained by quantum perturbed theory in this model. However, the amplitudes of the solitons depress along with increase of temperature of the medium, and it begins to disperse at 320 K. In the meanwhile, the damping of the medium can influence the states and properties of the soliton excited in α-helix protein molecules. The investigation indicates that the amplitude and propagated velocity of the soliton decrease, when the damping of medium increases. The soliton is dispersed at the large damping coefficient Γ=4 Γ₀ at 300 K. The results show that the soliton excited in the α-helix protein molecules with three channels is very robust against the damping and thermal perturbation of medium at biological temperature of 300 K. Thus we can conclude that the soliton can play important part in the bio-energy transport and the improved model is possibly a candidate for the mechanism of the energy transport in the α-helix proteins.

The physical properties of incompressible fluids used in heat exchangers, such as viscosity and thermal conductivity, change considerably with temperature during their normal operating conditions. This study investigates the heat transfer characteristics of microchannel flows by taking these variations into account. Our results demonstrate that the temperature effects are significant and must be taken into account if accurate predictions are to be obtained.

For simple plasma diagnostics for laser-induced plasma (LIP) under the condition of optically thin, taking the Cu I spectral lines produced by the laser-induced copper plasma, we investigate a simple method for temperature and electron density diagnostics, and we obtain the plasma temperature which has 10⁴ K order of magnitude and the averaged electron density is $3.8\times 10^{18}{\mathrm{\text{cm}}}^{-3}$, which are in agreement with that obtained by other methods. This investigation will be significant for spectral diagnostics for LIP.

ZnFe${}_{1.96}$La${}_{0.04}$O₄ nanocrystalline powders were synthesized by auto-combustion with the aid of glycine as fuel. The synthesized powders were subjected to heat treatment in air at constant temperatures (600–970${}^{\circ }$C) for a period of 2 h. The annealed powders were characterized by X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and UV–Vis–NIR spectroscopy. The as-synthesized and annealed powders formed spongy porous network structure with voids and pores. All the powders were found to be single phase nanomaterial with cubic spinel crystal structure and the desired composition; however, they contained strains, dislocations and lattice distortions. Some of these strains and dislocations are relaxed as a function of annealing temperature. The powders displayed direct and indirect optical band gaps. The energies of these band gaps were found to vary as a function of the induced strains and dislocations. It is suggested that the energy of the optical band gap in lanthanum-doped zinc ferrite nanocrystalline powders can be varied as a function of induced strains if the initial preparation conditions and the following heat treatments are controlled.

According to $p{K}_a$ measurements, it has been predicted that proton transfer would not occur in the radical cation of adenine–thymine (A:T). However, recent theoretical calculations indicate that proton transfer takes place in the base pair in water below the room temperature. We have performed simulations of proton transfer in the cation of B-DNA stack composed of 10 A:T base pairs in water from 20 K to 300 K. Proton transfer occurs below the room temperature, meanwhile it could also be observed at the room temperature under the external electric field. Another case that interests us is that proton transfer bounces back after $\sim$300 fs from the appearance of proton transfer at low temperatures.

A series of experiments pointed out that compact states of DNA condensed by multivalent cation prefer higher temperature. The condensed DNA takes elongated coil or compact globule states and the population of the compact globule states increases with an increase in temperature. At the same time, a recent experimental work carried out in buffer solution without multivalent cation points out that DNA persistence length strongly depends on the temperature. DNA persistence length is a key parameter for quantitative interpretation of the conformational properties of DNA and related to the bending rigidity of DNA. It is necessary to revolve the effects of temperature dependence of persistence length on DNA condensation, and a model including the temperature dependence of persistence length and strong correlation of multivalent cation on DNA is provided. The autocorrelation function of the tangent vectors is found as an effective way to detect the temperature dependence of toroid conformations. With an increase in temperature, the first periodic oscillation in the autocorrelation function shifts left and the number of segments containing the first periodic oscillation decreases gradually. According to the experiments mentioned above, the long-axis length is defined to estimate the temperature dependence of condensation process further. At the temperatures defined in experiments mentioned above, the relation between long-axis length and temperature matches the experimental results.

Based on the recent progress on both the temperature dependence of surface tension [H. L. Yi, J. X. Tian, A. Mulero and I. Cachading, J. Therm. Anal. Calorim.126 (2016) 1603, and the correlation between surface tension and viscosity of liquids [J. X. Tian and A. Mulero, Ind. Eng. Chem. Res.53 (2014) 9499], we derived a new multiple parameter correlation to describe the temperature-dependent viscosity of liquids. This correlation is verified by comparing with data from NIST Webbook for 35 saturated liquids including refrigerants, hydrocarbons and others, in a wide temperature range from the triple point temperature to the one very near to the critical temperature. Results show that this correlation predicts the NIST data with high accuracy with absolute average deviation (AAD) less than 1% for 21 liquids and more than 3% for only four liquids, and is clearly better than the popularly used Vogel–Fulcher–Tamman (VFT) correlation.

Based on the recent progresses on the corresponding state-based correlations for the temperature-dependent surface tension of saturated fluids [I. Cachadiña, A. Mulero and J. X. Tian, Fluid Phase Equilibr.442 (2017) 68; J. X. Tian, M. M. Zheng, H. L. Yi, L. B. Zhang and S. Z. Liu, Mod. Phys. Lett. B31 (2017) 1750110], we proposed a new correlation for saturated hydrocarbons. This correlation includes three fluid-independent parameters and inquires the critical temperature, the triple-point temperature and the surface tension at the triple-point temperature as inputs for each hydrocarbon. Results show that this correlation can reproduce NIST data with absolute average deviation (AAD) less than 1% for 10 out of 19 hydrocarbons and AAD less than 5% for 17 out of 19 hydrocarbons, clearly better than other correlations.

In this study, titanium dioxide was synthesized by using a hydrothermal technique at different growth temperatures. The study involved investigating the effects of growth temperature on crystal structure, surface area, morphology, and photocatalytic properties. The results indicated the growth of pure monoclinic titania. Additionally, an increase in growth temperature led to the formation of nanostructures to form nanowires and nanorods from nanospheres. The findings revealed variations in crystal quality at different growth temperatures. All samples displayed monoclinic crystal structure with the same molarity at different temperatures including 140${}^{\circ }$C, 160${}^{\circ }$C, and 180${}^{\circ }$C. Various parameters were optimized to grow nanowires and nanorods with a monoclinic crystal structure. The planes of the grown nanostructures were same across all the samples. The grown nanostructures were applied in the degradation of a crystal violet (CV) dye that is also used in optical applications. The study involved demonstrating the excellent photodegradation properties of CV by using a synthesized nanophotocatalyst and providing a detailed discussion on the effects of morphology and crystal structure with respect to photocatalytic properties. The findings also revealed the improved photocatalytic results with respect to nanostructures due to the presence of a broad light harvesting region and the lifetime of the photogenerated electron–hole pair.

In this study, compounds of B₆Si were irradiated using a ${}^{60}$Co gamma source that have an energy line of 1.25 MeV at the absorbed dose rates from 14.6 kGy to 194.4 kGy. Surface morphology images of the sample obtained by Scanning Electron Microscope (SEM) show that the crystal structure at a high absorbed doses $(D\ge 145.8\mathrm{\text{kGy}})$ starts to be destroyed. X-ray diffraction studies revealed that with increasing radiation absorption dose, the spectrum intensity of the sample was decreased 1.96 times compared with the initial value. Thermal properties were studied by Differential scanning calorimetry (DSC) method in the temperature range of 30–1000${}^{\circ }$C.

The optical performance of RGB LEDs used in displays is highly sensitive to the drive current and ambient temperature. The emitting intensity and dominant wavelength of RGB LEDs are investigated with the various currents and temperatures, and then the relevant mathematic models are proposed and summarized. Hence, the emitting intensity and dominant wavelength of RGB LEDs under any operating condition can be known from these models.

In order to satisfy the requirements of high quality and optimal material manufacturing process, it is important to control the environment of the manufacturing process. Depending on these processes, it is possible to improve the quality of the product by adjusting various gases. With the advent of the tunable laser absorption spectroscopy (TDLAS) technique, the temperature and concentration of the gases can be measured simultaneously. Among them, computed tomography-tunable diode laser absorption spectroscopy (CT-TDLAS) is the most important technique for measuring the distributions of temperature and concentration across the two-dimensional planes. This study suggests a three-dimensional measurement to consider the irregular flow of supplying gases. The simultaneous multiplicative algebraic reconstruction technique (SMART) algorithm was used among the CT algorithms. Phantom datasets have been generated by using Gaussian distribution method. It can show expected temperature and concentration distributions. The (HITRAN) database in which the thermo-dynamical properties and the light spectra of H₂O are listed were used for the numerical test. The relative average temperature error ratio in the results obtained by the SMART algorithm was about 3.2% for temperature. The maximum error was 86.8 K.

The transfer and low frequency noise characteristics of hydrogenated amorphous silicon thin film transistors (a-Si:H TFTs) were measured in the temperature range of 230–430 K. The variation of threshold voltage, field effect mobility and sub-threshold swing with increasing temperatures were then extracted and analyzed. Moreover, the shifts of low frequency noise in the a-Si:H TFT under various temperatures are reported for the first time. The variation of flatband voltage noise power spectral density with temperature is also calculated and discussed.

The impact of shape, size and temperature on elastic properties of nanomaterials is studied in this work. We have extended the melting temperature expression for nanostructures formulated by Guisbiers et al. and obtained the expression of elastic moduli and thermal expansivity for nanomaterials. An isobaric Tait equation of state is combined with Guisbiers model and the model so obtained is applied to analyze the shape, size and temperature effect on Young’s modulus and thermal expansivity in nanomaterials. The present computed results are compared with the simulated results and available experimental data. The Young’s modulus is observed to decrease as particle size is reduced while thermal expansivity increases with decrease in the size of nanomaterial. The Young’s modulus shows decrease with increase in temperature and decrement is observed maximum in spherical nanomaterials and minimum in nanofilms (NFs). Rate at which modulus is decreasing is found to increase as particle size is reduced. Good consistency of present predicted results with the available theoretical and experimental data is observed. The present calculated results are thus found consistent with the general trend of variation.

During the sputtering-deposition process, the temperature of film growth surface is more important than that of the substrate, which could seriously influence the film growth behavior. While, it is difficult to measure the temperature of film growth surface, because of the low space resolution of traditional temperature measurement systems. In this paper, the temperature of TiO₂ film growth surface and substrate were monitored by the home-made NiCr/NiSi film thermocouple and standard NiCr/NiSi K type wire thermocouple. With the same sputtering parameters, the temperature of TiO₂ film growth surface could reach $846.2\pm 3.9^{\circ }$C. While, the temperature of substrate was only about $305.8\pm 1.4^{\circ }$C. Finally, combining the temperature of film growth surface in sputtering-deposition process, the film growth behavior can be investigated and controlled in future.

Cells actively modify their behavior in on account of changes in their environment. The most important intrinsic parameter related to the intracellular environment is the temperature, the variations of which modify the dynamical behaviors of biomolecules. Indeed, an increase in temperature leads to an increase in fluidity which can damage the proteinous membrane and induce cellular death. If the temperature is extremely high, the proteins can be broken down or denatured as a consequence. However, concerning microtubules (MTs), we show that by their intrinsic behavior of self-organization, they are able to modulate temperature variations in order to avoid denaturation for values of temperature up to $T=50^{\circ }\mathrm{\text{C}}$. Above this temperature, there is a critical point at $T=57^{\circ }\mathrm{\text{C}}$ where the wave function completely disappears which is indicative of denaturation as the biological activity of the neuronal MTs is lost. We show that temperature variations change the viscosity of the cytosol which modifies the wave function and give rise to hybrid soliton structures. These hybrid solitons come from the collision of waves propagating along MTs. We also show that the supersonic velocity of these hybrid structures can be decreasing or increasing functions of environmental temperature.

To use supplying gases and energy resources efficiently, accurate measurement of irregular gas is necessary. The TDLAS (Tunable laser absorption spectroscopy) technique can be used to control and monitor the supplying gas conditions and combustion of industrial processes. Recently, CT-TDLAS (Computed tomography-tunable diode laser absorption spectroscopy) has been developed to measure the temperature and concentration field of gases. In this study, the 2-dimensional temperature distribution of the Propane-Air premixed flame in several mixing conditions of fuel has been measured by the constructed CT-TDLAS system. 2-Dimensional temperature distributions are measured by 16 path cells. Further, the third-order polynomial regression analysis was applied to resolve the absorption spectra from the incident and transmitted light for a particular gas. The SMART (simultaneous multiplicative algebraic reconstruction technique) algorithm has been adopted for reconstructing the absorption coefficients on the detecting area. As a result of comparing the temperature for the 2-dimensional detecting area using the thermocouple and CT-TDLAS technique, it has been verified that the relative error for the temperatures measured by the thermocouples and calculated by the CT-TDLAS was up to 8%.

In this paper, we study the multiple-parameter correlations for the surface tension of saturated liquids. The proposed three-parameter correlation requires only the critical temperature as inputs and is tested by using the NIST REFPROP data for 72 saturated liquids including refrigerants, alkanes and some other simple liquids such as argon, carbon dioxide, etc. It is found that this correlation well stands in the whole temperature range from the triple point to the critical point with high accuracy for 71 liquids with average absolute deviations (AADs) less than 5% and for 66 liquids with AADs less than 1%. These results are clearly better than the ones of other available correlations. This correlation can be directly used to estimate the value of the surface tension of the corresponding liquids at any temperature point from the triple point to the critical point. The accuracy of the predictions would clearly have economic benefits since it would allow improvement of process operating conditions, the development of new processes, the reduction of oversizing in the design of new equipment and even reduction of energy requirements.