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Ni-based alloys were prepared at different sintering temperatures in this study. The effects of sintering temperature on the volume fraction, morphology, and distribution of precipitates in Ni-based alloys, and its impact on mechanical properties were studied. The results show that the microstructure contains γ-Ni, Ni 3 Si, M 7 (B, C) 3 , M 23 (B, C) 6 , and a Si-rich multi element phase. The morphology of M 7 (B, C) 3 particles undergoes an evolution of small particles → mainly strip shape → mainly small block shape and nearly spherical shape, accompanying with the dissolution-reprecipitation process of M 7 (B, C) 3 particles caused by the diffusion of Cr element with the increasing of sintering temperature. Meanwhile, the M 23 (B, C) 6 particle is keeping aggregating and growing. The relative density, microhardness, and bending strength of Ni-based alloys also increase. Especially these properties are found to be increase quickly between 1025 °C and 1050 °C. The increase in microhardness and bending strength is attributed to the reduction in the number of residual sintering pores and the increase in the volume fraction and size of precipitates. In addition, the transition of fracture morphology from intergranular fracture mode to a combination of intergranular and partially transgranular fracture mode also contributes to the rise in bending strength. • γ-Ni, Ni 3 Si, M 7 (B,C) 3 , M 23 (B,C) 6 , and a Si-rich multi element phase. • Morphology of M 7 (B,C) 3 particles relates to dissolution-reprecipitation process. • Mechanical properties with residual sintering pores and boron carbide. [ABSTRACT FROM AUTHOR]

• The effect of temperature on non-slipping adhesive contact behavior is investigated. • The full analytical solutions of the anisothermal oscillatory stress fields are derived. • Both the temperature and inclined angle of the external force have significant influences on adhesion behaviors. • The non-oscillatory solutions can not always serve as a good approximation for the oscillatory solutions. The temperature difference always exists between contacting objects in various thermal bonding technologies, where the adhesion strength is found to be very sensitive to the temperature. In this paper, the anisothermal adhesive contact between an elastic cylinder subjected to the external force with an inclined angle and an elastic substrate is investigated based on the non-slipping JKR model, where the coupling effect between the normal and tangential tractions within the contact region is taken into consideration. The stated problem is reduced to a system of coupled singular integral equations, which can be solved with the analytical function theory. The full analytical solutions of the oscillatory stress fields are obtained for the first time by taking the series expansion of the integrand induced by the thermoelastic effect, which is of substantial significance. The relationship between the contact size and the external loadings is established by virtue of the Griffith energy balance criterion. The difference between the oscillatory and non-oscillatory solutions of stress fields is discussed in detail. Numerical results demonstrate that the oscillatory solution cannot be well approximated by the corresponding non-oscillatory solution for the cases of large Dundurs' index and external compressive force. Furthermore, it is found that both the thermoelastic effect and the inclined angle of the applied force have significant influences on the adhesive contact behaviors. The presence of temperature difference between contacting objects can either enhance or weaken the adhesion effect, which is related to the inclined angle of the external force. The results obtained from this paper may provide a new insight into the influence mechanism of the temperature on adhesion behaviors. [ABSTRACT FROM AUTHOR]

• For the first time, rubber fatigue criteria are correlated to materials, loads & temperatures. • The existing S-N base function is extended to account for the temperature effect. • The new S-N base function is proposed for elevated temperatures. • Both functions are validated on test data for two rubbers in a temperature range of 23-90°. • The accuracy of fatigue life prediction has achieved a scatter band of 1.5-2.0. It is desirable to obtain a fatigue criterion that can be correlated to different rubbers with both mechanical and temperature effects. In this paper, we investigated the possibility to correlate the S-N base function to temperature environments. The published experimental data consisting of temperatures ranging from 23-90 ° C for rubber samples with 50 and 45 Shore hardness were used to validate the existing S-N base function. Concomitantly, a new S-N base function was derived by adding two temperature functions from the test data. In the two criteria, both the thermal expansion and the shear modulus change with temperature were considered. The results have shown that for the 50 Shore hardness rubber, approximately 94% of the points predicted using the existing function and 100% of the points using the new function fell within a scatter band of 1.5. For 45 Shore hardness rubber at 90°C, all predicted points using the existing function fell along the upper limit line of a scatter band of approximately 2.0. On the contrary, all predicted points at 90 ° C fell within a scatter band of 1.35 using the new function. Therefore, this potential novel approach could be used in both the design stages of antivibration rubber components. [ABSTRACT FROM AUTHOR]

The hydrodeoxygenation of lignin-derived phenolic compounds holds great promise for biomass-derived liquid fuel production. However, achieving a consistently high cyclohexane yield poses a formidable challenge. In this study, NiCoAl catalysts were successfully synthesized using the solution combustion method for the hydrodeoxygenation of lignin-oil. The impact of calcination temperature on the preparation of NiCoAl catalysts was investigated. The results indicate that the selectivity of cyclohexane exhibits an initial increase followed by a decrease as the calcination temperature rises. Notably, the NiCoAl-600 catalyst reached 99.99% guaiacol conversion, with the highest selectivity of cyclohexane (97.96%) achieved. Characterization results demonstrate that the transition of the spinel structure from normal to inverse with rising calcination temperature. Moreover, the catalyst particle size initially decreases and then increases, while the oxygen vacancy concentration in the catalyst increases. It was found that these properties contribute to a better hydrodeoxygenation performances of guaiacol and other phenolic compounds over non-noble NiCoAl catalyst. Possible reaction pathway and mechanism are proposed and discussed. Additionally, the spinel-structured NiCoAl-600 catalyst has good thermal stability, ensuring potential application in the upgrading of lignin-oil. • Simple citric acid combustion method was applied to prepare non-noble NiCoAl catalyst. • The calcination temperature greatly influences particle size and oxygen vacancies and corresponding HDO performances. • High stability and improved carbon deposition resistance of the NiCoAl catalyst are achieved. [ABSTRACT FROM AUTHOR]

Due to the flame resistance and lubricity of ethylene glycol solution, an ethylene glycol piston pump can be used as motion sources for extreme operating conditions. In this paper, a novel variable liquid-properties thermal network model (VLTNM) is proposed to analyze the thermodynamic characteristics of piston pump. The VLTNM considers the interaction between the changes in properties of liquid passing through piston pump and the heat generated by motion, and calculates the heat transfer between solid and liquid through a thermal network. A numerical calculation model for VLTNM is established in MATLAB using simscape language, and the results show that the temperature rise of outlet liquid can be reduced by 10.36%, when the thermal conductivity of shell is doubled. The working pressure has a positive effect on temperature variation, which is more significant in high-temperature environments, while the volume fraction of ethylene glycol solution has a negative effect. Additionally, a high load helps to improve the efficiency of piston pump, while the temperature rise caused by high pressure can also reduce the efficiency. When the working pressure increases from 6 MPa to 10 MPa, the efficiency decline of piston pump increased by 1.12%. Besides, comparing the two models of variable and non-variable liquid properties, there is a significant deviation in steady temperature of outlet liquid. The deviation in low temperature is more prominent, with a deviation of 6.1% when the temperature of air is 10 °C. Finally, the predicted steady temperature by VLTNM is in good agreement with the experimental data in reference, with a prediction error of less than 2.01%. [ABSTRACT FROM AUTHOR]

Recently in engineering science, studies have been conducted in the field of using large-amplitude vibrations, especially when a system undergoes a superharmonic excitation. This is accomplished in order to determine the location and depth of a crack in a structure, promote the energy absorption process, and for system identification purposes. Some studies demonstrated that energy absorption can be developed for a bistable energy harvester system (EHS). Additionally, small-scale systems have been implemented recently for the sake of energy harvesting in remote microstructures with no physical connection to the outside world. Therefore, in this regard, this article addresses the nonlinear size-dependent vibrations of a nanocomposite microbeam reinforced with carbon nanotubes (CNTs) (CNTRC microbeam) exposed to temperature enlargement. On the other hand, due to the high slenderness ratio of a CNT, the aggregation of CNTs in a CNTRC structure is unavoidable. Accordingly, assuming the unshearability in the microbeam and based on the modified couple stress theory (MCST), the investigation of the nonlinear features of the superharmonically excited aggregated CNTRC microbeam is presented. In this respect, the effect of temperature as well as the CNT aggregation on the steady-state response of the superharmonically stimulated aggregated CNTRC microbeam is discussed. The mechanical properties of the desired structure are estimated according to the Eshelby–Mori–Tanaka model. Size-dependent nonlinear partial equations are treated directly by applying the method of multiple scales (MMS). Through the establishment of a widespread case study, the size effect and the temperature and aggregation impacts on the nonlinear response have been elucidated. It is discussed how a bistable steady-state response is influenced by the heterogeneity, that is initiated by the CNT aggregation, and temperature. One of the most important results is the increase of the maximum steady-state response, at primary resonance analysis, as a result of the increase in the heterogeneity and temperature that leads to a bistable response that can be implemented for the optimal energy harvesting purpose. Moreover, heterogeneity and temperature enhance the frequency bandwidth of the bistable steady state response. At both primary and superharmonic resonance analyses, they reduce the force bandwidth of the bistable steady state response. They also move the bistable response to a smaller force domain. At superharmonic resonance analysis, for a smaller excitation frequency than the first natural frequency, a catastrophic bifurcation happens as a result of the heterogeneity decrement and temperature increment. Different effects of temperature and heterogeneity are observed for an excitation frequency above the first natural frequency. In this condition, the frequency bandwidth for the bistable response constantly enhances with the development of heterogeneity and temperature. Furthermore, the bistable response postpones to higher excitation frequencies. • Heterogeneity and temperature increase frequency bandwidth of bistable steady state response. • Temperature decreases the disparity of bistable branches. • Heterogeneity and temperature reduce force bandwidth of bistable steady state response. • Heterogeneity and temperature reduce disparity of the associated bistable branches. • Heterogeneity and temperature shift the bistable response to a smaller force domain. [ABSTRACT FROM AUTHOR]

This study proposes a method to analyze the dynamic characteristics of an improved composite box girder bridge with corrugated steel webs (ICBGBCSW). In this study, a theoretical analysis was first conducted. By comprehensively considering temperature, shear deformation and stiffness correction, the natural frequency formula of simply supported ICBGBCSW was derived based on the stress equivalence principle. The accuracy of the proposed frequency formula was verified through the finite element results and measurement results of the simply supported ICBGBCSW in the field. Then, sensitivity studies were performed to investigate the effects of the temperature-equivalent axial eccentric force, elastic modulus change, shear deformation, height-span ratios, and width-span ratios on the natural frequency of the ICBGBCSW. Finally, the natural frequency formula of continuously supported ICBGBCSW was derived by applying the three bending moment equations, and the fundamental frequency formula of continuously supported ICBGBCSW was proposed. The proposed method is able to consider both the influences of temperature, shear deformation and stiffness correction and has good performance in analyzing the natural frequency of the ICBGBCSW. This study provides a technique support for the modification of the fundamental frequency formula of the ICBGBCSW in the current code, and provides a reference for the analysis of dynamic characteristics and design of the ICBGBCSW. • An analytical formula for calculating the natural frequencies of the ICBGBCSW is proposed. • The accuracy of the natural frequency formula is verified using experiments and numerical simulations. • The effects of shear deformation and temperature on the frequencies of the ICBGBCSW are investigated. • A formula for predicting the fundamental frequency of the continuously supported ICBGBCSW is developed. [ABSTRACT FROM AUTHOR]

In this paper, a thermo-mechanical sequential coupling mesoscopic simulation method was established and verified, which considered the interaction between steel tube and meso-components of concrete due to the difference in thermal parameters, as well as the low-temperature effect on mechanical parameters. On the basis of heat conduction analysis, the damage evolution and failure mechanism of CFST column under axial compression were subsequently revealed, and the effects of low temperature (20, −30, −60 and −80 °C), cross-section size (160, 320, 480 and 640 mm), width-thickness ratio (27, 36, 53 and 107) and cross-section shape (square and circular) on axial compression performance and the corresponding size effect of CFST columns were quantitatively analysed. Research results show that the low-temperature action can enhance the nominal peak strength and residual strength of CFST column, but weaken the ductility. As the cross-section size increases from 160 to 640 mm, all the nominal peak strength, nominal residual strength and peak strain of circular CFST column decrease with the maximum reductions of 16.2, 28.7 and 16.9%, respectively. Besides, the low-temperature action can enhance the size effect on nominal peak strength of CFST column with the maximum increase of 68.8%. Whether at ambient or low temperature, the size effect on nominal peak strength of square column is stronger than that of circular one. The size effect behaviour on axial compressive peak strength at various temperatures can be also well described by the previous proposed prediction formula. The research results of this paper can provide reference for the engineering application of large-sized CFST columns in the extreme low-temperature environment. • The thermo-mechanical sequential coupling method at low temperature was developed. • The effect of low temperature, width-thickness ratio, cross-section size and cross-section shape were considered. • The mechanical properties and corresponding size effect of CFST columns at low temperature were quantitatively analyzed. [ABSTRACT FROM AUTHOR]

Based on the concept of environment-friendly development strategy, green preparation method is crucial. Therefore, starch-derived micron solid carbon spheres (SCs) were fabricated via spray-drying followed by carbonization processing, in which is no any harmful substances in whole process. Through tuning the carbonization temperature, SCs with a moderate degree of graphitization and intrinsic defects can be obtained. The microstructure, permittivity and microwave absorption of SCs were studied. Results show that the SCs with a larger number of micropores is composed of nanocrystalline regions and amorphous areas. The paraffin-based composites with 25 wt% SCs carbonized at 800 °C displays a strong microwave loss feature, the minimum reflection loss of −64.8 dB at 9.02 GHz with thickness of 2.57 mm. Meanwhile, the effective absorption band (<-10 dB) can reach 3.1 GHz with the thickness of 2.22 mm, covering 78% of X-band, which because of its good impedance matching and dielectric loss ability resulted from the synergistic effect between the microstructure and graphitization. This work offers a facile, larger-scale and environmental-friendly method for the preparation of micron carbon-based absorbents that can serves as an alternative to nano-scale absorbents to overcome the poor dispersion of nanoparticle in the matrix. [Display omitted] • Starch-derived micron solid carbon sphere with complex nano-scale structure was fabricated by facile and large-scale method. • The micron sphere carbonized at different temperature exhibits a strong absorption of the RL min of −64.8 dB at 9.02 GHz. • Carbon microspheres can be served as an alternative to nanoscale fillers to overcome poor dispersion in the matrix. [ABSTRACT FROM AUTHOR]

Roasting temperature plays an important role in the chemical reaction of vanadium‑titanium magnetite. In order to investigate the effect of roasting temperature on pellet motion characteristics, a non-cohesive and multi-element particle model of discrete element method (DEM) was constructed. On this basis, different diameter pellets (d p = 20.38 mm, 25.02 mm, 29.67 mm, 35.52 mm) with different roasting temperature (298 K ≤ T ≤ 1473 K) were selected to explore the effects on pellet velocity distribution, discharge mass flow rate, wall pressure and average voidage. Our results reveal a large change in the movement characteristics of pellets involving chemical reactions during high-temperature production. The mean voidage is negatively correlated with the diameter. The minimum deviations of pellet velocity distribution and discharge mass flow rate at different roasting temperature were 20.16% and 21%, respectively, and the maximum deviations of wall pressure and average voidage were 63.47% and 7.0%, respectively. [Display omitted] • The deviations of pellet motion at different temperatures were explored by DEM. • The average variance of particle movement velocity is logarithmic to the D / d p. • The effect of temperature on wall pressure is positively correlated with pellet size. • The average voidage has a positive correlation with the pellet equivalent diameter. [ABSTRACT FROM AUTHOR]

The effect of temperature on adhesion is neglected in classical adhesive contact theories. However, an increasing number of experimental results indicate that temperature has a prominent effect on adhesion behaviors. In this study, the anisothermal adhesive contact behaviors between two transversely isotropic piezoelectric cylinders with different initial temperatures is investigated by virtue of the generalized JKR model, where the contact interface is assumed to be perfectly bonded. The considered problem is reduced to coupled singular integral equations, which is derived by using the Fourier integral transform. The closed-form solutions of anisothermal generalized stress fields are obtained by taking the series expansion of the integrand induced by temperature difference. The effect of temperature difference on adhesion behaviors of two different types of layered piezoelectric structures under the action of mechanical-electro loadings is revealed. It is found that the pull-off force and contact size at pull-off moment decrease with increasing the temperature difference. The adhesion weakening effect induced by temperature difference diminishes when the electric loading is exerted. The results derived from this paper shed lights on understanding the adhesive contact behaviors of piezoelectric materials in the presence of temperature difference. • The anisothermal non-slipping JKR model for piezoelectric materials is established. • The effect of temperature difference on adhesion behavior of different types of layered piezoelectric structure is revealed. • The closed-form solutions for the contact stresses and normal electric displacement in the presence of temperature difference are obtained. • The presence of temperature difference can weaken the adhesion effect between dissimilar piezoelectric solids. • The adhesion weakening effect induced by temperature difference diminishes when the exerting electric loading is exerted. [ABSTRACT FROM AUTHOR]

Three kinds of four-step three-dimensional braided silicon carbide fiber-reinforced silicon carbide matrix composites with pyrocarbon interface were prepared through precursor infiltration and pyrolysis under 1100 °C, 1300 °C, or 1500 °C, and they were oxidized at 1300 °C with simulated air. The effects of pyrolysis temperature on the microstructure and oxidation behavior of the composites were investigated. Results indicated that the SiC crystallite size and crystallinity of the as-fabricated composites increased with increasing pyrolysis temperature. During oxidation, the three composites initially underwent similar near-linear mass-loss stages associated with the consumption of carbon component. Subsequently, they exhibited different mass-gain stages associated with the oxidation of SiC component. The composites prepared at 1100 °C followed a linear mass-gain rule, whereas the composites prepared at 1300 °C and 1500 °C followed a two-step parabolic mass-gain rule. The mechanism of mass-gain behavior change was proposed, which might be associated with the pyrolysis-temperature-dependent precursor-derived ceramic SiC microstructure and its evolution during oxidation. [ABSTRACT FROM AUTHOR]

Three types of SiC f /SiC composites with a four-step three-dimensional SiC fibre preform and pyrocarbon interface fabricated via precursor infiltration and pyrolysis at 1100 °C, 1300 °C, and 1500 °C were heat-treated at 1300 °C under argon atmosphere for 50 h. The effects of the pyrolysis temperature on the microstructural and mechanical properties of the SiC f /SiC composites were studied. With an increase in the pyrolysis temperature, the SiC crystallite size of the as-fabricated composites increased from 3.4 to 6.4 nm, and the flexural strength decreased from 742 ± 45 to 467 ± 38 MPa. After heat treatment, all the samples exhibited lower mechanical properties, accompanied by grain growth, mass loss, and the formation of open pores. The degree of mechanical degradation decreased with an increase in the pyrolysis temperature. The composites fabricated at 1500 °C exhibited the highest property retention rates with 90% flexural strength and 98% flexural modulus retained. The mechanism of the mechanical evolution after heat treatment was revealed, which suggested that the thermal stability of the mechanical properties is enhanced by the high crystallinity of the SiC matrix after pyrolysis at higher temperatures. [ABSTRACT FROM AUTHOR]

Three tempering temperatures at high temperature zone (690 °C, 700 °C and 710 °C) are selected into the quenching-and-tempering processes and performed on the rolled Cr-Mo steel to develop API-5CT-C110 casing steels. Effect of tempering temperature on sulfide stress cracking (SSC) behavior is quantitatively evaluated and further explored by characterizing the microstructure and crystallography. The results show that the strength of steel decreases with tempering temperature, but the SSC susceptibility is reversely varied. EBSD analysis indicates that the steel tempered at lower temperature (690 °C) generates more grains with high Taylor factors, which are difficult to yield, leading to the increasing of dislocation density and more susceptible to SSC. • Steel tempered at higher temperature generates more grains with lower Taylor factors. • Grains in steel with low Taylor factors inhibits the increase of dislocation density. • Tempering decreases dislocation density of steel, resulting in superior SSC behavior. [ABSTRACT FROM AUTHOR]

Ni20Cr splats were sprayed onto polished substrates at different preheating temperatures in an Ar atmosphere by low pressure plasma spray to reveal the dominating factor driving the bonding formation of the splats. The splat morphology, microstructure and splat-substrate interface were characterized by SEM, EBSD and TEM. The interface for examination of typical splats was prepared by focus ion beam (FIB). Disk-like splats were obtained on AISI 304 stainless steel substrate preheated to temperatures of 100 °C (cooling down from 350 °C) and 350 °C, whereas few short projections in the periphery were observed on the splat deposited at 550 °C. For all splats, three typical distinct zones with different microstructure features were observed on the splat surface by SEM and EBSD, including central coarse grain zone, transitional medium grain zone and peripheral fine grain zone. The interface bonding formation is closely related to the microstructure distribution. TEM observations demonstrated that the bonded interface only formed in the central coarse grain zone which provides a facile approach to access the bonding of plasma sprayed splat. The present work also reveals that increasing the substrate temperature cannot significantly improve the interface bonding due to the existence of oxide layer. The mechanism dominating the formation of those microstructures was also discussed. • Ni20Cr splats are deposited at different substrate temperatures. • The surface of splats presents three kinds of microstructure. • Oxidation during preheating process inhibits interface bonding formation. • Microstructure of splats and interface bonding formation are correlated. [ABSTRACT FROM AUTHOR]

Highlights • Verification, validation, and application for the CFD-DEM method coupled with heat exchange are conducted. • Fluid velocity and particle diameter have a more remarkable influence on convection than conduction. • Particle temperature in the riser and the system presents a two-peak histogram distribution. Abstract For a single isolated particle, the effect of overlap displacement on conduction and the effect of particle diameter/fluid velocity on convection are comprehensively studied using a CFD-DEM method coupled with heat exchange. Moreover, the model is further validated in a pseudo-2D bubbling fluidized bed and the influence of operating parameters (i.e., fluid velocity, particle diameter, and mass loading) on heat transfer contribution is deeply revealed. The results show that the fluid velocity and particle diameter have a more remarkable influence on convective heat transfer than conductive heat transfer. Besides, the particle-fluid convection dominates the heat transfer while the particle-particle conduction is almost negligible. The particle-fluid-particle conduction occupies about 10% of the total heat transfer. Finally, the model is successfully applied in a circulating fluidized bed. The average mass fractions of solid materials in the riser, cyclone, and dipleg are 0.737, 0.023, and 0.240, respectively. Solid internal circulations and lower solid velocities in the horizontal part of dipleg lead to a two-peak histogram distribution of particles temperature in the riser and the system. [ABSTRACT FROM AUTHOR]

Abstract China Railway Track System II slab track is widely applied to China high-speed railway. Under the high temperature conditions, it tends to produce different degrees of arch at the joints between prefabricated slabs, which will affect the track irregularity and safe operation of high-speed trains. In this paper, considering the buckling instability of track structure, the arching mechanism of the slab joints was investigated by establishing a 3D finite element model of the CRTSII slab track. Combined with the field investigation, the damage process of joint concrete and its effects on the arching instability were analyzed. The results show: 1) The construction of joint concrete is difficult to control on site, which leads to inferior quality compared to prefabricated slab. The worse quality of joint concrete corresponds to a smaller amplitude of temperature rise causing joints damage and a greater damage area. 2) When the amplitude of temperature rise of the slab is over 37 °C, various damage emerges in the narrow joint and the middle of wide joint, resulting in the eccentric compression. 3) The temperature gradient load will cause the propagation of interface gap between slab and CA mortar layer, which aggravates the arching instability of slab, especially when the height of gap exceeds 1.5 mm. This research is expected to provide guidance for the optimization design, maintenance and damage control of slab track. Highlights • The joint concrete will produce various damage under high temperature conditions. • The damage areas mainly occur in the middle of wide joint and narrow joint. • Temperature effect and eccentric compression result in the arching instability. • The temperature gradient load will aggravate the interface gap and arching instability. • Maintain the track structure in time when the gap exceeds 1.5 mm at height. [ABSTRACT FROM AUTHOR]

Abstract Fundamental gas transport properties of a novel thermally rearranged polymer (TPBO) prepared from a co-polyimide precursor with controlled triptycene molar content are discussed. He, N 2 , CH 4 , CO 2 and C 2 H 6 sorption isotherms were experimentally measured in the range 5–50 °C and up to 32 atm and analyzed with the dual mode model. Water vapor sorption and diffusion at 35 °C was also investigated. TPBO exhibits larger gas and vapor sorption capacity relative to previously reported thermally rearranged polymers. The dual mode parameters retrieved from the analysis of single gas sorption isotherms were used to estimate a priori the sorption behavior in mixed gas conditions. The predicted mixed gas solubility-selectivity is significantly higher than ideal solubility-selectivity and it is comparable to that exhibited by other glassy polymers. Gas and vapor diffusion coefficients in TPBO were estimated from the solution-diffusion model and from sorption kinetics, respectively, and are larger than in previously reported thermally rearranged polymers. The dual sorption-mobility model indicates that the polymer rigidity significantly affects gas diffusion coefficients. CO 2 /CH 4 diffusivity-selectivity was larger than in other glassy polymers, pointing out the superior size-sieving ability provided by triptycene units. Water vapor sorption experiments revealed that TPBO is more hydrophilic relative to previously reported thermally rearranged polymers: theoretical models were exploited to speculate water vapor distribution in the polymer matrix. Graphical abstract fx1 Highlights • Gas solubility in TPBO is larger relative to other high performance polymers, except PIM-1. • TPBO exhibits larger diffusivity-selectivity relative to other polymers. • TPBO is more hydrophilic relative to previously reported TR polymers. • Polymer rigidity affects gas diffusion behavior. [ABSTRACT FROM AUTHOR]

Highlights • The loading amount of horseradish peroxidase (HRP) up to 139.82 mg g−1. • The stability of HRP had been greatly enhanced after immobilization. • The immobilized HRP possessed excellent storage ability and reusability. • The degradation efficiency of phenol catalyzed by the immobilized HRP reached 94.4% within 10 min. Abstract In the present study, a novel and efficient immobilization for horseradish peroxidase (HRP) had been developed by using 6-arm magnetic composite microsphere (Fe 3 O 4 @PAA-6-arm-PEG-NH 2) containing 6-arm polyethylene glycol (6-arm-PEG-NH 2) and Fe 3 O 4. The morphology and chemical properties of Fe 3 O 4 @PAA-6-arm-PEG-NH 2 were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectra (FTIR), X-ray powder diffraction (XRD), vibrating sample magnetometer (VSM) and thermogravimetric analysis (TGA). The immobilization conditions and loading capacity of the carrier toward HRP were also investigated. According to the results, the optimum immobilization conditions were as follows: glutaraldehyde concentration of 0.10 mol L−1, the carrier concentration of 7 mg L−1, the temperature of 35 °C and immobilization time of 180 min. The loading capacity of the immobilized HRP arrived to 139.82 mg g−1 (RSD = 0.87%). Compared with free HRP, the stability of the immobilized HRP had been enhanced in a wide range of temperature and pH. The activity of the immobilized HRP retained 71.05% of its initial activity after 60 days storage. It was also found that the activity of the immobilized HRP retained 61.06% of its initial activity after eight times of successive reuse. The immobilized HRP could hydrolyze phenol to 94.4% within 10 min. It proved that the immobilized HRP could improve the performance of HRP, which had a good prospect in biological application. [ABSTRACT FROM AUTHOR]

Abstract The temperature- and rate-dependent yielding of twinning-induced plasticity (TWIP) steels containing various carbon contents are investigated in the present work. The activation volume and the activation energy have been determined. The magnitude of these thermal activation parameters for high-carbon TWIP steels are largely different from those of conventional fcc metals, implying the fundamental role of carbon on the thermally activated dislocation activities in carbon-added TWIP steels. A constitutive model, which rationalizes yielding as the thermally assisted bowing out of dislocations under the pinning effect of carbon solutes, is proposed, and for the first time quantitatively predicts the thermal activation parameters of TWIP steels as a function of carbon content. Based on the modeling results of thermal activation parameters, the overall temperature- and rate-dependent yield stresses of TWIP steels containing various carbon contents are predicted, showing good agreements with experimental results. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Abstract This study aims to study the temperature behaviors and quantitatively diagnose water exits for multi-fractured horizontal wells (MFHWs) in low-permeability gas reservoirs (LPGRs) with two-phase flow. Firstly, a transient temperature prediction model is developed on the basis of mass, momentum and energy conservation with consideration of a variety of subtle heat effects (e.g. Joule–Thomson effect, thermal expansion etc.). Subsequently, synthetic cases are simulated to illustrate the temperature behaviors of a two-phase MFHW with identical/non-identical fractures. The sensitivity analysis indicates that the existing of Non-Darcy flow and gas-phase slippage effect reduces the wellbore temperature. The wellbore temperature shows significant sensitivity to reservoir permeability and fracture half-length. Then, by simulating the temperature profile of MFHWs with different water/gas ratio (WGR) of each fracture, the unique characteristics of wellbore temperature variation under each WGR situation are observed. That provides the potential to diagnose the water exits of MFHWs from temperature measurement. Finally, we apply the model to a field case and the results validated the feasibility of the developed model to simulate the temperature behavior of MFHWs in LPGRs. Highlights • Transient temperature prediction model for MFHW with two-phase flow in LPGRs. • Consideration of non-Darcy flow, slippage effect and a variety of subtle heat effects. • Simulation of temperature behavior and sensitivity analysis. • Quantitative diagnosis of water exit locations from temperature profile. [ABSTRACT FROM AUTHOR]

Abstract Effects of service temperature on the tensile properties and microstructural evolution of tensile specimens manufactured by commercial pure (CP) titanium subjected to laser shock peening (LSP) were investigated. Special attention was paid to the microstructural features at the top surface close to the fracture zone of the failed LSPed specimens at 20 °C, 150 °C, 250 °C, and 350 °C by means of transmission electron microscopy (TEM) observations. Results indicated that the ultimate tensile strength (UTS) of LSPed specimens gradually decreased, but the area reduction and elongation of LSPed specimens increased with the increment of service temperature. Furthermore, the influence mechanism of service temperature on the microstructural evolution of the LSPed CP titanium consisted of two modes: (a) ultra-high strain rate inhibited the dislocation motion at a lower temperature which was more prone to the occurrence of deformation twinning, and (b) ultra-high strain rate was easier to activate dislocation motion at a higher temperature, making deformation twinning disappear in the plastic deformation layer of CP titanium. Graphical abstract Image 1 Highlights • Increasing temperature is easier to generate necking phenomenon of LSPed CP titanium. • Ultimate tensile strength of LSPed specimens decreased with increasing temperature. • Microstructural features of failed specimens at various temperatures were presented. • Influence mechanism of temperature on microstructure of LSPed specimen was revealed. [ABSTRACT FROM AUTHOR]

Abstract The humidity sensitive elements of TiO 2 /Graphene oxide nanocomposites (TGOs) were obtained by interdigital Ag-Pd electrode substrate. The resistance-temperature characteristic and humidity sensitivity of TGOs humidity sensors were characterized by voltammetry in the range of 25–80 °C and between a relative humidity of 11.3–93.6%RH. The results indicated that the calcination temperature obviously affected the resistance variation of the humidity sensitive elements. It can be seen that the resistance of TGOs humidity sensors decreased firstly and then increased with increasing calcination temperature. Meanwhile, the activation energy increased from 12.47 kJ/mol to 54.47 kJ/mol, then decreased to 16.72 kJ/mol, and finally increased to 19.66 kJ/mol. The resistance gradually reduced with the increase in environmental humidity for TGOs humidity sensitive elements calcined at 300 °C. The resistance of TGOs humidity sensors calcined at 350, 400, 450 and 480 °C increased first and then decreased with increasing environmental humidity. The humidity hysteresis of TGOs humidity sensors calcined at 300 °C increased to a maximum value of 24.33%, and decreased to 6.02% at 450 °C. Particularly, TGOs humidity sensors showed p-type nature of the semiconductors in the low RH range (< 62.1%RH) and showed n-type nature of the semiconductors in the high RH range (> 62.1%RH). [ABSTRACT FROM AUTHOR]

Highlights • Attempt to combine two original vaporization models to take advantages of both. • The species solver is added to the HFM framework, the coupling strategy is assessed. • The feasibility of switching between the two frameworks is demonstrated. • The conservative level set method is utilized to reduce unphysical mass loss. • Results show good agreement with the analytical and experimental data. Abstract This paper proposes a vaporization model for detailed numerical simulations of a reactive interface. The proposed model represents a preliminary attempt to combine vaporization models based on heat flux and species mass flux to take each model’s advantages concerning numerical accuracy, robustness and applicability. We utilize a conservative level set method to reduce unphysical mass loss in capturing the deformable interface, and the ghost fluid method to accurately impose various jump conditions across the interface. Four validations are conducted to demonstrate both the strengths and limitations of the two original models. Since the vapor mass fraction is relevant in realistic applications, we add the species solver to the heat flux based model and assess the coupling strategy in different situations. The feasibility of switching between the two frameworks in the coupled vaporization model is also demonstrated. Finally, the coupled model is applied to simulations of deformable/moving droplet under high-ambient-temperature conditions. The results of the simulations are consistent with analytical and experimental data. Although additional work is required, the coupled vaporization model exhibits potential as a means for modeling spray combustion. [ABSTRACT FROM AUTHOR]

Highlights • A comprehensive temperature prediction model of a MFHW in LPGR is developed. • Non-Darcy flow and radial flow in the hydraulic fractures are considered. • Obtain of wellbore temperature profile and fracture temperature diagnosis chart. • Good match of predicted temperature profile and measured data in filed application. Abstract This study aims to interpret the temperature behavior of a cemented multi-fractured horizontal well (MFHW) in a low-permeability gas reservoir (LPGR) during production. First, considering heat conduction, heat convection, thermal expansion, viscous dissipation, and the Joule–Thomson effect, a comprehensive numerical temperature prediction model is developed under a single-phase condition. The developed models are formulated for the reservoir and wellbore domains based on mass, momentum, and energy conservation. The non-Darcy law is applied to the numerical models, and radial flow in the hydraulic fractures is accounted for when the reservoir and wellbore models are coupled. These developed models are solved numerically by the finite difference method. Then, synthetic cases demonstrate the models’ ability to predict the temperature behavior and clarify the change regularity of the wellbore temperature profile for an MFHW in an LPGR. The effects of pressure interference among hydraulic fractures on the inflow rate are analyzed. Based on the sensitivity of arriving temperature to the fracture parameters, an approach to plotting fracture parameter diagnosis charts are introduced. In addition, a field case is provided to illustrate the application and feasibility of the new models on the basis of the accurate simulated results of wellbore temperature profiles. [ABSTRACT FROM AUTHOR]

Highlights • Performed Phase I water vapor diffusion tests at different temperatures. • Determined diffusion parameters under only water vapor pressure using 3-D model. • Converted diffusion parameters under water vapor to parameters under 1 atmosphere. • Established Arrhenius models between temperature and water vapor diffusivity. • Established Arrhenius models between temperature and moisture retention capability. Abstract This study investigated the effect of temperature on Phase I water vapor diffusion in asphalt mixtures. A test protocol with a series of Phase I water vapor diffusion tests was designed and performed on hot mix asphalt specimens and fine aggregate mixture specimens. A Gravimetric Sorption Device was utilized to perform the diffusion tests on three replicate specimens of each mixture type at five temperatures. A relative humidity differential was established between the inside and the outside of the test specimen and drove water vapor to diffuse into the specimen until reaching equilibrium. The mass of the test specimen was continuously measured at a frequency of every 5 s using the magnetic suspension balance. The mass of water molecules diffused into the specimen at any time point was calculated to be the measured mass of the specimen at that time point less the initial weight of the specimen. A previously developed 3-D diffusion model was applied to the test data of all replicate specimens to determine the Phase I water vapor diffusivities and the moisture retention capabilities per unit mass under only water vapor pressure at various temperatures. These two parameters were converted into the corresponding values under 1 atmosphere, which were increasing with the increase in temperature. It was found that water vapor diffused into the asphalt mixtures at a significantly lower speed under 1 atmosphere than under only water vapor pressure. It was also observed that an asphalt mixture had a much smaller moisture retention capability per unit mass under 1 atmosphere than under only water vapor pressure. The Arrhenius equation was selected based on theoretical justification to quantify the effects of temperature on diffusivities and moisture retention capabilities per unit mass. Excellent goodness of model fit was achieved for every replicate specimen with an R2 value larger than 0.95. The Arrhenius equation was demonstrated to be an appropriate theoretical model that was able to accurately characterize the temperature dependency of both diffusivities and moisture retention capabilities per unit mass. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Ultrasonic conditions significantly affect extraction efficiency. • Guava leaf polysaccharides (GLP) has good antioxidant activity. • GLP exhibits remarkable hypoglycemic activity in vitro. Abstract Plant polysaccharides possess multiple physiological activities. Box-Behnken design (BBD) was employed to optimize the ultrasound-assisted extraction of polysaccharides from guava leaves (GLP). It was found that ultrasonic time, temperature and power has a significant effect on the extraction efficiency. The yield of GLP was 1.00 ± 0.04% under the optimal condition of extraction time of 20 min, temperature of 62 ℃ and ultrasound power of 404 W. The DPPH and ABTS+ radical scavenging rate of GLP was 56.38% and 51.73% at 100 μg/mL, respectively. The rate of inhibition of α-amylase by GLP was only 14.06% at 1 mg/mL; however, its α-glucosidase inhibition rate reached 99.54% at 100 μg/mL. These results suggested that the ultrasound-assisted extraction for GLP is effective and environmentally friendly and GLP has wide application potentials as natural antioxidants and α-glucosidase inhibitors. [ABSTRACT FROM AUTHOR]

Abstract Bond exchange reaction (BER) induced stress relaxation in covalent adaptable network (CAN) polymers can be leveraged to realize the reshaping, thermoforming, and functional shape changing of cross-linked polymers. However, there is no existing study to reveal how the BERs and viscoelastic relaxation of polymer chains would affect the thermomechanical behaviors of CANs individually or synergistically. In this work, we synthesized polyimine-based CANs with BER activation temperature close to the network glass transition temperature. A thermo-viscoelastic constitutive model based on the Bernstein-Kearsley-Zapas (BKZ) theory was established to separate the contributions of BERs from those of chain relaxation. Assisted by the model, we investigated the effects of BERs and chain relaxation on the energy dissipation in the loading-unloading cycle, the degree of stress relaxation, as well as the dynamic responses of CANs under different thermal-temporal conditions. The findings in this paper provide theoretical guidance to design and fabrication of CAN based devices or structures. Graphical abstract Image 1 Highlights • BER and relaxation of polymer chains dominate the energy dissipation of CANs at high and low temperatures, respectively. • These two relaxation mechanisms are coupled at medium temperature, whose boundary depends on the applied strain rate. • A second peak in the tan δ curve is corresponding to the damping effects of BER on the polymer networks. • As decreasing the frequency of dynamic loads or the BER activation energy, the second peak shifts to a lower temperature. [ABSTRACT FROM AUTHOR]

Recent studies have suggested that thermal and visual comfort are correlated, although the causality underlying this correlation is unclear. Personal control of correlated color temperature (CCT) provides individual visual comfort, but its effects on other parameters such as thermal comfort and cognitive performance remain underexamined. Therefore, we investigated if personal control of CCT can, on top of visual comfort, enhance thermal comfort and cognitive performance in office scenarios while exposed to mild cold (17 °C) using a 2x2 within-subject design. Sixteen participants were initially exposed to CCT of either 2700 K or 5700 K for 70 min. In the subsequent 70 min, participants either had free control of CCT or no control. As expected, personal control of CCT improved visual comfort and mitigated perceived eye-related symptoms. However, it did not significantly affect thermal comfort for either antecedent CCT. When the antecedent CCT was 5700 K, personal control of CCT increased alertness and physiological arousal, improved the planning and verbal cognitive performance, but, unexpectedly, decreased performance on mental spatial manipulation tasks. Additional analyses then explored the role of the psychological and personalization effects of personal control by controlling for the actual CCT. These suggest that control benefited visual comfort, eye-related symptoms, perceived task performance, pleasure, alertness and physiological arousal. This study is one of the first studies to demonstrate that visual comfort does not causally affect thermal comfort. Personal control of CCT benefits visual appraisals and eye-related symptoms, sometimes improves alertness, but differentially influences cognitive performance depending on the task type. • Visual comfort does not casually affect thermal comfort. • Preference for correlated color temperature (CCT) depends on the initial CCTs. • Personal control of CCT benefits visual appraisals and eye-related symptoms. • Personal control of CCT differentially affects different cognitive performances. [ABSTRACT FROM AUTHOR]

In this study, Na 3 Zr 2-x Nb 0.8x Si 2 PO 12 , Na 3 Zr 2-x Ti x Si 2 PO 12 , Na 3 Zr 2-x Y x Si 2 PO 12-0.5x , Na 3 Zr 2-x Zn x Si 2 PO 12-x ceramics with x = 0.1, 0.2, 0.3 and 0.4 were sintered to explore the influence of the valence state and the content of dopants on the conductivity of NASICON solid electrolyte. Archimedes method, X-ray diffraction, scanning electron microcopy and complex impedance spectroscopy were used to characterize the sintered samples. Results show that the dopant with +2 oxidation state cations improves the bulk conductivity mainly due to the less electrostatic interactions between Zn 2+ ions and Na + ions. The optimal doping content of Nb 5+ , Ti 4+ and Y 3+ doped NASICON ceramics is 0.1 mol and that of Zn 2+ doped NASICON ceramic is 0.2 mol for the highest ionic conductivity. Among all the doped NASICON ceramics, Na 3 Zr 1.8 Zn 0.2 Si 2 PO 11.8 ceramic displays the highest total conductivity of 1.44 × 10 −3  S/cm and bulk conductivity of 3.41 × 10 −3  S/cm at room temperature. Furthermore, doping strategy both increases the density and decreases the sintering temperature of Na 3 Zr 2 Si 2 PO 12 ceramic. [ABSTRACT FROM AUTHOR]

The extractable compounds are a very important part of coal and play an important role in the pyrolysis of coal. To further understand the effect of the extracts on the structure and pyrolysis behaviours of coal, Naomaohu (NMH) lignite and Hutubi (HTB) bituminous coal were extracted with pyridine and swollen with its solvent vapor. The pyrolysis process was performed in a fixed-bed reactor. Thermogravimetric analysis (TGA) of the coal samples was carried out on a thermogravimetric (TG) analyser. The pore structure characteristics of the coal samples and their chars obtained from pyrolysis at different temperatures were measured by the mercury intrusion porosimetry (MIP) method. The components of the pyrolysis gas were detected by gas chromatography (GC). It was found that the extraction and swelling processes enlarged the pore size and improved the porosity of the coals to some extent. Compared with the pyrolysis of the raw coal, that of the swollen coal resulted in a higher tar yield owing to the destruction of the cross-linked structure and the variations in the coal structure; the tar yield for the pyrolysis of all the residues decreased significantly, but the gas yield increased, where the volume of the CO gas mainly increased. The NMH residue char obtained from pyrolysis of the residue at different temperatures had a lower proportion of micropores than the HTB residue char. The extractable compounds will be converted to gas-phase (e.g. volatiles) and liquid-phase (e.g. colloids) products during the pyrolysis process, which could stabilise the free radical fragments, form coke in the pore structure of the char and increase the number of new micropores formed. [ABSTRACT FROM AUTHOR]

In this work, the effects of Al* generated in situ in hydriding on the dehydriding of Mg-Al alloys prepared by Hydriding Combustion Synthesis (HCS) and Mechanical Milling (MM) were studied. Thermal analysis showed that the peak dehydriding temperature of MgH 2 was reduced by 25 °C (or 11 °C) when 20 at% Al was added in HCS (or MM) process, even though, the same dehydriding reaction of 17MgH 2 + 12Al*/Al → Al 12 Mg 17 + 17H 2 was observed. Isothermal dehydriding at 300 °C for 3 h demonstrated that it took 81 min for HCS+MM-MgH 2 to desorb 50% of hydrogen, while only 24 min was required for HCS+MM-Mg 80 Al* 20 . The apparent activation energy for dehydriding of MgH 2 was reduced from 144.3 ± 7.19 kJ/mol for HCS+MM-MgH 2 to 118.8 ± 6.73 kJ/mol for HCS+MM-Mg 90 Al* 10 . The scanning electron microscopy/energy dispersive spectroscopy and X-ray photoelectron spectroscopy analyses revealed that the Al* in situ generated from the hydriding of Al 12 Mg 17 in HCS would significantly decrease dehydriding temperature and improve dehydriding kinetics of the MgH 2 -Al composites because of a uniform distribution, the shortening reaction diffusion length, providing unoxidized surfaces to react with MgH 2 and the high chemical activity of Al*. [ABSTRACT FROM AUTHOR]

The microstructural characteristics of three medium carbon steels, namely MnCrB, NiCrSi and NiCrMoV containing steels, have been investigated when the steels were hardened by quenching in water or oil from different austenitisation temperatures (i.e. 850, 900 and 950 °C). The microstructure was characterised using optical microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy, and X-Ray diffraction technique, whereas the mechanical properties were measured by Vickers hardness testing, V-notched Charpy impact testing and tensile testing. The microscopy observations suggested a fully martensitic microstructure, whereas martensite was considerably finer in NiCrSi and NiCrMoV steels compared to MnCrB steel. Moreover, the NiCrSi and NiCrMoV steels showed significantly higher strengths and lower ductility than MnCrB steel. The results suggested that the small additions of alloying elements and different prior austenite grain sizes were mainly responsible for the observed microstructural and mechanical properties variations. [ABSTRACT FROM AUTHOR]

The impact behaviours of steel tube-confined recycled aggregate concrete (STCRAC) following exposure to elevated temperatures of 20 °C, 200 °C, 500 °C and 700 °C were experimentally investigated using a 100 mm-diameter split Hopkinson pressure bar (SHPB). The recycled coarse aggregate (RCA) replacement ratios were set as 0, 50% and 100%. The effect of RCA replacement ratio and exposure temperature on the impact properties of STCRAC were analysed in terms of failure modes, stress-strain time history curve and dynamic increase factor (DIF). The results show that the fire-damaged STCRAC can maintain its integrity during impact load. However, there were evident degradations in the dynamic behaviour of STCRAC after exposure to high temperatures of 500 °C and 700 °C. The ultimate impact strength, impact secant modulus and residual impact strength of STCRAC obviously decreased because of the damage due to high temperature exposure. But the degradations of both the ultimate impact strength and impact secant modulus of STCRAC under impact loading were less severe than those under quasi-static loading. The remaining strength factor and the DIF tended to increase with the raise of the elevated temperatures. Overall, during the impact loading, the fire-deteriorated STCRAC exhibited excellent impact behaviour. [ABSTRACT FROM AUTHOR]

In this paper, a working pair of CaCl 2 –LiBr–LiNO 3 (8.72:1:1)/H 2 O has been proposed for a single-stage absorption refrigeration system driven by solar energy collected with flat plate solar collectors or vacuum glass tube solar collectors. The crystallization temperature, saturated vapor pressure, specific heat capacity, and specific enthalpy of the proposed working pair were systematically measured. Results showed that under the same refrigeration conditions, the required solar collecting temperature of the single-stage absorption refrigeration cycle based on CaCl 2 –LiBr–LiNO 3 (8.72:1:1)/H 2 O was 7.7 °C lower than that based on LiBr/H 2 O. Furthermore, the COP of the cycle based on CaCl 2 –LiBr–LiNO 3 (8.72:1:1)/H 2 O was approximately 0.04 higher than that based on LiBr/H 2 O. The corrosion rates of 316L stainless steel as the structure material and copper as the heat exchange material for the proposed working pair were low enough for practical applications. [ABSTRACT FROM AUTHOR]

Mullite-based ceramic tiles were successfully prepared using only high-alumina fly ash (HAFA) at relatively low sintering temperatures (1100–1400 °C). The effects of alkali activation on the chemical composition, mineral phase, and morphology of the HAFA were respectively characterised by ICP-OES, XRD, and SEM methods. The alkali-activation pretreatment not only modifies the chemical composition of HAFA to match that of mullite, but also can introduce Na-rich compounds to promote sintering. The macroscopic and microscopic characteristics of the fully ash-based ceramic tiles formed at different sintering temperatures were examined. The ceramic samples sintered at 1300 °C exhibited optimal post-sintering properties (relative density: 90.85%, water absorption: 0.10%, rupture modulus: 109.67 MPa, linear shrinkage: 15.70%, and apparent porosity: 0.68%) and a well-developed cubic puncheon-shaped mullite morphology. Finally, through the isothermal sintering method, the melt viscosities and the sintering kinetics were calculated theoretically, and the results show that the alkali activation could dramatically reduce the melt viscosity and the apparent activation energy. This research may provide a new method in utilising the vast amounts of HAFA waste to produce mullite-based ceramic tiles at low costs. [ABSTRACT FROM AUTHOR]

In this article, the kinetic stabilization processes of ultrathin polystyrene (PS) films with different molecular weights ( M w ) and interfacial conditions were monitored by controlling the cooling rate. We found that, for the high M w PS ultrathin film, the fictive temperature ( T f ) of liquid-cooled sample shows large change in a broad range of cooling rates while the kinetic stability proves no obvious variation. By using the low M w PS ultrathin film, the kinetic stability begins to show cooling rate dependence, which indicates the modification of kinetic stability of shorter polymer chains is easier. With the aid of fluorescence resonance energy transfer (FRET) method, the variations of inter-chain proximity of polymer chains with the cooling rate were investigated for both oligomer and high M w PS thin films, and the former is more remarkable. Given that the further the inter-chain proximity, the higher the degree of excess free volume, there are more space for the rearrangement of chains of low M w polymer ultrathin films to reach energy-minimum configurations during cooling. Additionally, the shift of T g,dyn after cooling can be enlarged or removed by introducing a mobile interface or burying the free surface. These results suggest that the kinetic stability of liquid-cooled ultrathin films may stay unchanged when fictive temperature varies obviously, and it can be modified by controlling the molecular weight of polymer and the interfacial condition. [ABSTRACT FROM AUTHOR]

The effects of ambient temperature on stroke death in China have been well addressed. However, few studies are focused on the attributable burden for the incident of different types of stroke due to ambient temperature, especially in Beijing, China. We purpose to assess the influence of ambient temperature on hospital stroke admissions in Beijing, China. Data on daily temperature, air pollution, and relative humidity measurements and stroke admissions in Beijing were obtained between 2013 and 2014. Distributed lag non-linear model was employed to determine the association between daily ambient temperature and stroke admissions. Relative risk (RR) with 95% confidence interval (CI) and Attribution fraction (AF) with 95% CI were calculated based on stroke subtype, gender and age group. A total number of 147, 624 stroke admitted cases (including hemorrhagic and ischemic types of stroke) were documented. A non-linear acute effect of cold temperature on ischemic and hemorrhagic stroke hospital admissions was evaluated. Compared with the 25th percentile of temperature (1.2 °C), the cumulative RR of extreme cold temperature (first percentile of temperature, −9.6 °C) was 1.51 (95% CI: 1.08–2.10) over lag 0–14 days for ischemic type and 1.28 (95% CI: 1.03–1.59) for hemorrhagic stroke over lag 0–3 days. Overall, 1.57% (95% CI: 0.06%–2.88%) of ischemic stroke and 1.90% (95% CI: 0.40%–3.41%) of hemorrhagic stroke was attributed to the extreme cold temperature over lag 0–7 days and lag 0–3 days, respectively. The cold temperature's impact on stroke admissions was found to be more obvious in male gender and the youth compared to female gender and the elderly. Exposure to extreme cold temperature is associated with increasing both ischemic and hemorrhagic stroke admissions in Beijing, China. [ABSTRACT FROM AUTHOR]

Thermoelectric radiant panel (TERP) system is a new prototype of radiant system with fast cooling/heating speed, stable operation, and easier system control. The full and deeper understanding of heat transfer of TERP could be beneficial for system design, operation and control. The purpose of this paper is to establish a three-dimensional analytical model of TERP in both steady and dynamic state which could be used as a useful tool for further research. The method of mirror virtual heat sources was adopted to transform original heat conduction problem to the superposition of temperature solutions of radiant panel in infinite plane. In addition, this method can offer a highly flexible treatment on boundary conditions. The basic conduction problem was solved by the method of separation of variables and the temperature field subjected to non-functional finite-plane heat source was modeled by Duhamel theorem in simulation algorithm. Thermal network RC model for TEM and copper cube was integrated with the analytical model of radiant panel for simulation of TERP. The simulation accuracy of three-dimensional temperature field of TERP was verified by comparing with experimental results in both steady and dynamic state. In order to understand the simulation difference between the previous 2-D and new 3-D model, a comparative study was implemented under different model parameters arrangements. This numerical comparative investigation can provide a basic guidance on the application of 2-D and 3-D model. And this study offered a solid and sophisticated system model for TERP. [ABSTRACT FROM AUTHOR]

In this paper, a new type of microcapsulated phase change materials (BS-TD/PALMA microPCMs) with butylstearate (BS) and tetradecanol (TD) as binary cores and poly (allyl methacrylate) (PALMA) as shell, was prepared for thermo-regulated fibers. The surface morphology, particle size distribution, thermal properties and thermal stability of the resulting microcapsules were investigated. The results showed that the melting temperature and mean diameter of BS-TD/PALMA microPCMs were 20.1-32.6 °C and 1.3 ± 0.3 μm, respectively. The latent heat and encapsulation efficiency reached up to 73.3 J g −1 and 76.4 wt.%, respectively. BS-TD/PALMA microPCMs displayed good thermal stability. They were greatly favorable for the application to thermo-regulated fibers. [ABSTRACT FROM AUTHOR]

This paper presents a high-power IGBT testing platform for uneven temperature conditions and its design criteria. Considering the influence of layout parasitic parameters on the measurement results, commutation rules and independent junction temperature control, a universal high-power switching characterization platform is built and operated. Importantly, it is capable of 3.6 kA current level test requirement, which can cover the largest current level for the state-of-the-art IGBT modules. To improve the test accuracy of double pulse test method, a compensation algorithm is proposed to eliminate the circuit power loss under high current test conditions. Moreover, in order to simulate the uneven junction temperature effects occurring in real life, the junction temperatures of inspected IGBT and freewheeling diode are controlled independently. Quantitative analyses of the switching characteristics for junction temperatures up to 125 °C are performed. [ABSTRACT FROM AUTHOR]

• Thermally-thick particles featured with intra-particle temperature inhomogeneity. • Effect of intra-particle temperature inhomogeneity considered by corrected 0D model. • The multi-fluid model evaluated with bubbling fluidized bed experiments. • Intra-particle temperature inhomogeneity plays an important role in CFD simulation. • The computational efficiency of the corrected 0D model comparable to a 0D model. The multi-fluid model has been widely used to study heat transfer between gas and solid in bubbling fluidized beds. However, zero-dimensional (0D) model has been commonly used. The model assumes a uniform temperature distribution, which is only reasonable for thermally-thin particles (Biot number (Bi) < 1). However, one-dimensional (1D) model considering intra-particle temperature inhomogeneity inside particles is difficult to be implemented in multi-fluid model. To solve this issue, a corrected coefficient is introduced to quantitively feature the effects of intra-particle temperature inhomogeneity inside particles on external heat transfer, which forms a corrected 0D model. The corrected coefficient is correlated as a binary function of Bi and dimensionless temperature. The results of particle-scale modeling show that temperature profiles predicted by the corrected 0D model are the same as those of the 1D model for both thermally-thin and thermally-thick particles, while the 0D model overestimates heat transfer between particles and surrounding gas. The corrected 0D model is further implemented in the multi-fluid model to simulate particle cooling and heating process in bubbling fluidized beds. The results predicted by CFD simulations with both the 0D and the corrected 0D models are in good agreement with the experimental data of thermally-thin particles. For both the cooling and heating processes, a significant difference is observed for thermally-thick particles, indicating the importance of considering intra-particle temperature inhomogeneity in multi-fluid modeling. Consistent with the results of particle-scale modeling, the corrected 0D model predicts a smaller heat transfer rate between the gas and solid phases, as compared to the 0D model. Additionally, computational efficiency of the corrected 0D model is comparable to that of the 0D model. [ABSTRACT FROM AUTHOR]

TiC/W ultra-fine powders were produced by one-step activation and chemical reduction process. The powders were consolidated by spark plasma sintering (SPS) at 1800 °C to suppress grain growth during sintering. The grain size, relative density and the Vicker hardness HV 0.2 of the bulk sample fabricated by SPS were 3 μm, 98.6% and 471, respectively. The reduced Young's elastic modulus of the sintered W–1 wt.% TiC composites was 382.7 GPa. As the temperature rises from room temperature (RT) to 1100 K, the thermal conductivity of pure W and W–1 wt.% TiC composites decreased with the same trend. However, the thermal conductivity of the samples was both above 120 W/m K at RT. [ABSTRACT FROM AUTHOR]

The Be films were prepared by thermal evaporation at the different heating temperature on the Si(100) and glass substrates, respectively. The prepared samples were characterized and the results showed that the grain diameter in the Be films transited from 30nm to 300nm, the surface roughness of the Be films changed from 4nm to 60nm, and the film growth rate increased from 0.9nm/min to 7.3nm/min during the heating temperature was varied between 980°C and 1120°C. Meanwhile, the results indicated the crystallinity of the Be films changed better, and their electric resistance decreased rapidly. However, the microhardness of the Be films firstly increased from 6.98GPa to 10.93GPa, lastly decreased to 5.69GPa. The intrinsic relationship between the Be film’s crystallinity and their electric properties and mechanical properties was also investigated. The findings explained the heating temperature had a great influence on properties of the Be films grown by thermal evaporation. [ABSTRACT FROM AUTHOR]

In marine environment, concrete structures can corrode because of the PH alkalinity of concrete paste; and the salinity PH is heavily related with the concentration of salt in aqueous solutions. In this study, an optical fiber salinity sensor is proposed on the basis of an etched FBG (EFBG) coated with a layer of polyimide. Chemical etching is employed to reduce the diameter of FBG and to excite Cladding Mode Resonance Wavelengths (CMRWs). CMRW and Fundamental Mode Resonance Wavelength (FMRW) can be used to measure the Refractive index (RI) and temperature of salinity. The proposed sensor is then characterized with a matrix equation. Experimental results show that FMRW and 5th CMRW have the detection sensitivities of 15.407 and 125.92 nm/RIU for RI and 0.0312 and 0.0435 nm/°C for temperature, respectively. The proposed sensor can measure salinity and temperature simultaneously. [ABSTRACT FROM AUTHOR]

In the present paper, we report novel room-temperature hydrogen sensors based on palladium oxide (PdO) loaded tungsten oxide (PdO-WO 3 ) nanohybrids. We synthesized WO 3 nanorods by hydrothermal method. Then the as-synthesized nanorods were mixed into PdCl 2 solution with a subsequent thermal treatment to form PdO-WO 3 nanohybrids. XRD and XPS test confirmed that PdO-WO 3 nanohybrids were successfully prepared. FE-SEM and HRTEM images showed that PdO nanoparticles were distributed on the surface of WO 3 nanorods in the nanohybrids. UV–Vis spectra indicated that broader visible light absorption range of PdO-WO 3 composites was obtained when compared with that of pure WO 3 . The obtained PdO-WO 3 sensors exhibited good responses to ppm-level H 2 gas at room temperature under visible light illumination, and the best sensing performance was achieved upon exposure to blue light illumination. The best sensing performance was comparable to the counterpart performed at an elevated temperature between 200 and 250 °C. [ABSTRACT FROM AUTHOR]

Two low-firing ceramics Li 2 MGe 3 O 8 (M = Ni, Co) were prepared using the solid state reaction method and their microwave dielectric properties were characterized. X-ray diffraction analysis showed that both ceramics crystallized into a cubic spinel structure. Both ceramics were well densified at temperatures lower than 960 °C. Li 2 NiGe 3 O 8 ceramic sintered at 940 °C with relative density of ~95.2% obtained the optimum microwave dielectric properties with a relative permittivity ( ε r ) ~8.6, a quality factor ( Q×f ) ~42,200 GHz (at 12.2 GHz), a temperature coefficient of resonance frequency τ f ~ −78.2 ppm/°C. For Li 2 CoGe 3 O 8 , the ceramic sintered at 950 °C had a relative density of 95.4%, a ε r of 9.0, a Q×f of 40,500 GHz (at 12.6 GHz) and a τ f of −42 ppm/°C. The negative τ f values could be tuned by forming composite ceramics with rutile TiO 2 . Chemical compatibility measurement indicates that both ceramics did not react with silver. [ABSTRACT FROM AUTHOR]

A dynamic second-order moment closure model is developed for turbulent combustion in the form of large eddy simulation. The filtered reaction rate is directly closed in the form of Arrhenius law, and the whole temperature exponential function is treated as a single variable to avoid the traditional Taylor series expansion. The sub-grid unresolved reaction rate is modeled with a second-order moment closure model. All the coefficients in the sub-grid models are evaluated by the dynamic procedures. To validate and evaluate this model, a priori validation using a DNS database and posteriori validation by LES of the Sandia piloted jet flame (Flame D) and the Sydney bluff-body swirling flame (SM1) are performed. The results demonstrate that the dynamic second-order moment closure model coupled with LES is able to reasonably predict turbulent combustion even with simple chemistry, and has potential to predict more complex combustion with detailed reaction mechanism and acceptable computational cost. [ABSTRACT FROM AUTHOR]

In this work, chrome-tanned leather waste were activated with sodium hydroxide (NaOH) to prepare a porous adsorbent for lead (II) adsorption. The effects of various preparation parameters like the concentration of NaOH, the size of leather particles, the activation time and the activation temperature were studied. Under optimum preparation condition, the alkali-activated porous leather particles (AAPLP) were obtained after vacuum freeze-drying. AAPLP was characterized with BET, SEM, FT-IR, TG and XPS. It was found that the BET surface of AAPLP was twice more than unactivated leather waste. Additionally, it could be inferred that ion-exchange and complexation happened during the adsorption process between AAPLP and lead (II). The effects of solution pH, temperature and contact time on adsorption capacity of AAPLP for lead (II) have also been investigated. The experiment data was fitted well with Freundlich isotherm and followed pseudo-second-order kinetics. Meanwhile, the kinetic data was governed by intraparticle diffusion model and it was found that the adsorption process contained three stages. [ABSTRACT FROM AUTHOR]