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When an impurity with a light mass is inserted into a crystal, it can undergo a high-frequency oscillation referred to as a local vibrational mode (LVM). A Fermi resonance may occur between the LVM and lower-frequency modes of the defect. The LVM may also interact with phonons or the electromagnetic field. Understanding these interactions can help model and control diffusion, defect reactions, and thermal conductivity. LVMs have been probed in semiconductors using pressure and alloying as experimental parameters, resulting in anticrossing between localized and extended vibrational modes. These types of vibrational interactions could play an important role in the stability and thermal properties of organic–inorganic hybrid semiconductors. The coupling between an LVM and electromagnetic wave yields an "LVM polariton," an excitation that has significant vibrational and electric-field amplitudes. [ABSTRACT FROM AUTHOR]

This work describes the preparation and properties of a novel category of thermosetting microwave absorbing composite materials. The composites were prepared by a simple solution casting process, employing high temperature resistant polysilylaryl-enyne (abbreviated as PSAE) resin as matrix and perovskite CaMnO 3 (abbreviated as CMO) ceramic filler as absorbent filler. The microstructure, electromagnetic, wave absorbing and thermal properties of the CMO-PSAE composites were all examined. The results showed that the increasing fraction of CaMnO 3 filler not only densified the microstructure of the composites, but also greatly improved their temperature resistance, thermal conductivity and wave absorption properties. The CMO-PSAE composite doped with 50 vol% CaMnO 3 ceramic filler showed the strongest ability to absorb electromagnetic waves, with an effective absorption bandwidth (EAB) of 4.16 GHz and a minimum reflection loss is −53.01 dB. Besides, the thermal conductivity of the composite reached 1.106 W/(m·K). Furthermore, this composite material has exceptional thermal resistance, with the highest T d5 reaching 650 °C. Composites with varying doping levels can be used for specific performance needs in practical scenarios. Thus, such novel CMO-PSAE composites exhibit potential applications in the electromagnetic countermeasure field under high-temperature environments. [ABSTRACT FROM AUTHOR]

In this work, 1-aminoethyl-3-methylimidazolium bromide ionic liquid was used to modify the surface of graphene nanosheets (GNs) through "π–π" interaction to achieve good dispersion and conductivity. By introducing ionic liquid-modified graphene nanosheets (IGNs) into the PI matrix, the ultra-lightweight and multifunctional IGNs/PI aerogels were prepared via freeze-drying and thermal imidization. Benefiting from the porous structure and the introduction of conductive IGNs, the IGNs/PI aerogels exhibit excellent electromagnetic wave (EMW) absorption properties, compression properties, thermal insulation properties and thermal stability. Notably, when the volume content of IGNs is 10%, the IGNs/PI-10 aerogels show the best EMW absorption performance with a minimum reflection loss (RLmin) of −24.8 dB at 2.44 mm and an effective absorption bandwidth (EAB) of 3.6 GHz at 3.00 mm. These promising characteristics including excellent EMW absorption, compression properties and thermal insulation endow IGNs/PI aerogels great application prospects as multifunctional EMW absorbers. [ABSTRACT FROM AUTHOR]

[Display omitted] Regulating electromagnetic parameters and thus improving impedance matching characteristics by multi-component design is regarded as a prospective approach to obtain highly efficient electromagnetic wave absorption materials. Whereas, it is still challenging to fabricate microwave absorbers with strong absorption capacity and durability in harsh conditions. Based on the above considerations, three-dimensional porous multi-functional manganese oxide/nickel/carbon microspheres had been designed and prepared through a combined approach of facile solvothermal reactions and subsequent carbonization processes. The textural characteristic examinations demonstrated that, numerous manganese oxide and Ni nanoparticles of 15–20 nm in diameter were well dispersed in the carbon-based microspheres of approximately 0.8–1 μm in size. Microwave absorption property evaluation indicated that the minimum reflection loss reached up to −53.6 dB at 9.5 GHz, and effective absorption bandwidth of 3.7 GHz was achieved at matching thickness of merely 2.0 mm. The electromagnetic wave attenuation mechanisms analysis displayed that excellent impedance matching and various dissipation pathways, including magnetic loss, interfacial and dipole polarization relaxation synergistically contributed to the high microwave absorption performances of the porous composites. Radar cross-sectional simulation and photothermal measurements verified that the materials were supposed to have promising foregrounds in complicated circumstances. [ABSTRACT FROM AUTHOR]

Using light-emitting diodes (LEDs) for visible light communication has become an alternative choice of radio source due to channel crowding of the radio-frequency (RF) signal. The modulation bandwidth of LEDs is usually limited by the spontaneous carrier lifetime in multiple quantum wells. Here, sub-GHz modulation of GaN-based LED employing photonic crystal (PhC) nanostructure is demonstrated. The guided photonic modes of the LEDs are modulated by the RF signal. Both carrier lifetime of lower- and higher-order modes are studied in time-resolved photoluminescence (TRPL) at room temperature. The f-3dB-J curve of the PhC LED exhibits a higher bandwidth than the typical LED structure. At 11.41 kA/cm², the optical -3-dB bandwidth (f-3dB) up to 234MHz of the PhC LED (PhCLED) is achieved. Our studies on TRPL at different wavelengths and frequency response at different injection current densities conclude that the higher operation speed is attributed to faster radiative carrier recombination of extracted guided modes from the PhC nanostructure. [ABSTRACT FROM AUTHOR]

The synthesis of zinc doped bismuth ferrite has been successfully carried out using the solgel autocombustion method. The thermal properties through the TGA test showed that the mass began to stabilize in the range of temperature 600 - 750°C as the indication of the formation of single-phase BiFe0.88Zn0.12O3 nanocrystalline. It is obtained from the SEM test that the surface shape of BiFeO3 of zinc doping indicated that it was not homogeneous and there was clotting. Through the EDS test, it is shown the ratio of (% wt) Bi: Fe between calculations and experiments of 1:1 which indicates a stoichiometric reaction. The XPS study found Zn2p element has entered the Fe2p element. The electrical properties through the LCR test showed that the existence of Zn doped BiFeO3 nanocrystalline reduces the dielectric constant value at a frequency of 100 kHz - 1 MHz. The dielectric constant values are stable at high frequency which can potentially be applied to electromagnetic waves. [ABSTRACT FROM AUTHOR]

SiC was introduced as nanowires and multilayered structure matrix to modify C/C composites, then SiC nanowires reinforced C/(PyC-SiC) n (SM-CS) composites were prepared. The electromagnetic shielding and thermal conductive properties were investigated and the further relationship between these properties and the number of cycles of preparation (N) was also studied. The results showed that total shielding effectiveness (SET) values of modified composites were all higher than 30 dB which meant more than 99.9% electromagnetic wave was shielded. And the SET values increased with the rising of N (SM-CS4--47.6 dB > SM-CS3--42.7 dB > SM-CS2--37.1 dB). With the rising of N , not only the conductivity of SM-CS N composite increased, but also the interfaces inside the matrix increased, leading to a continuous increase in reflection and absorption of electromagnetic waves. Meanwhile, the thermal diffusivities and conductivities of the SM-CS composites in the temperature range from 25 to 1500 °C were all higher than those of pure C/C composites, and they were also almost increased by N. That was because the improvement of SiC nanowires in heat transport was very large, and even exceeded the reducing of multilayered structure. Due to these good functional properties, the modified composites would exhibit excellent potential in aerospace field. [ABSTRACT FROM AUTHOR]

Porous Fe3O4/Fe/SiO2 core/shell nanorods were fabricated, in which the diameter of the pores was 5–30 nm. The magnetic and electromagnetic properties were investigated. The temperature dependent magnetic measurements showed that these nanorods were ferromagnetic with a Verwey temperature of 129 K. The electromagnetic data indicated that effective complementarities between the dielectric loss and the magnetic loss were realized, suggesting that they have excellent electromagnetic wave absorption properties. Thus the porous core/shell nanorods could be used as a kind of candidate absorber. [ABSTRACT FROM AUTHOR]

[Display omitted] • Porous coral-like Co/CoO/RGO hybrid aerogels are successfully developed. • The special structure brings multiple loss modes and good impedance matching. • Achieving high EM wave loss, hydrophobicity and thermal insulation properties. • DFT simulations are adopted to verify the interface polarization of interfaces. Addressing the growing issue of electromagnetic radiation calls for urgent exploration of effective electromagnetic wave absorbers. Herein, a series of coral-like Co/CoO nanoparticles/reduced graphene oxide (Co/CoO/RGO) hybrid aerogels were synthesized via a freeze drying-thermal reduction strategy. Their advantages involving porous interconnected framework, abundant heterogeneous interfaces, and integration of dielectric/magnetic units could bring multiple loss modes. By manipulating the Co(CO 3) 0.5 (OH)·0.11H 2 O (CCOH) addition and reduction temperature, the electromagnetic parameters could be tuned, ultimately resulting in optimal absorption capability with maximal reflection loss of –32.4 dB and effective bandwidth of 4.2 GHz. More importantly, excepting the high electromagnetic wave loss, Co/CoO/RGO hybrid aerogels also exhibit good hydrophobicity and thermal insulation properties, making them suitable for application in harsh environment. Besides, the special structure and multiple components lead to multiple heterointerfaces in aerogels, the resultant interface polarization is deemed to contribute to electromagnetic wave loss. Here, Density Functional Theory (DFT) simulation based on first-principles is adopted to verify the contribution of interface polarization from the theoretical level. According to the simulation results, the electron-occupied states near the Fermi level are significantly different among the different phases comprising the heterointerfaces, and there is a noticeable accumulation of charge at these interfaces, successfully affirming the interface polarization behavior at different interfaces. [ABSTRACT FROM AUTHOR]

Abstract WO 3 -SnO 2 nanosphere (NS) composites with different structures and morphologies are successfully synthesized by a facial hydrothermal method. Two kinds of gas sensors were fabricated from WO 3 -SnO 2 NS composites of hollow structure with average diameter of 360 nm and solid structure with average diameter of 42 nm by varying the synthesis temperature. The as-prepared composites were annealed at 500 °C for 4 h in atmosphere before the characterization and sensing performance test. The crystalline structures, morphologies and surface compositions of the annealed WO 3 -SnO 2 NS composites are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photo-electron spectroscopy (XPS) techniques, respectively. The results of gas sensing tests show that WO 3 -SnO 2 NS composites with hollow structure exhibit the superior sensing behavior, including sensitivity, response-recovery rate and selectivity, as compared to the composites with solid structure. The WO 3 -SnO 2 NS composites presented in this work shows a high sensitivity, fast response and selectivity towards acetone. The surface conductivity changes of WO 3 -SnO 2 NS induced by the surface gas adsorption and desorption is proposed to responsible for the corresponding sensing behaviors. The WO 3 -SnO 2 NS composites with hollow structure presented in this study have potential practical applications in the field of gas sensor devices. Highlights • WO 3 -SnO 2 nanospheres are synthesized by the hydrothermal method. • WO 3 -SnO 2 of hollow structure demonstrates the superior sensing behaviors. • WO 3 -SnO 2 nanospheres show the higher response toward acetone. • The sensing mechanism caused by the adsorption and desorption. [ABSTRACT FROM AUTHOR]

Fabric-based electromagnetic wave (EMW) absorption materials are desirable owing to their inherent flexibility, cost-effectiveness, and easily conformable lightweight structures. However, the problems such as high density and susceptibility to abrasion limit their applications and service life. Herein, flexible fabric-based EMW absorption material (FEMWAM) were prepared by a multiscale synergistic approach. At the microscopic scale, CF@NiCo 2 O 4 @MnO 2 absorbents with enhanced impedance matching and interfacial polarization are prepared by solvent method and hydrothermal process. The influence of heterostructure on the electromagnetic response is also examined. At the macroscopic scale, flexible FEMWAM are prepared by freeze-drying. The electromagnetic parameters of FEMWAM was effectively regulated by altering the amount of the CF@NiCo 2 O 4 @MnO 2 absorbents, which achieve excellent EMW absorption performance and thermal insulation property while maintaining flexibility. The minimal reflection loss (RL min) of −27.8 dB can be achieved at a thickness of 2.70 mm, and an EAB covering the complete X-band can be obtained when the thickness is in the range of 3.20–3.26 mm. The large thickness range provides convenience for the control of dimensional accuracy in actual production, so as to better adapt to practical applications. These findings provide effective guidance for the preparation of EMW absorption materials with excellent flexibility, thermal insulation properties and absorption performance. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, the structure-property relationships of a clay ceramic with organic additives (biomass and biochar) are investigated to develop an alternative material for thermal energy storage. The firing transformations were elucidated using X-ray pair distribution function analysis, differential scanning calorimetry, and scanning electron microscopy. It was found that the biomass increased the porosity, which resulted in a decrease of the specific heat capacity. On the other hand, the biochar remained in the clay ceramic without any interaction with the clay matrix up to 950°C. The specific heat capacity of the clay ceramic increased from 1.20 to 1.49 kJ/kg·K for a 30 wt% addition of biochar. The clay ceramic with a 30 wt% addition of biochar also conserved a high flexural strength of 11.1 MPa compared to that of the clay ceramic without organic additives (i.e., 18.9 MPa). Furthermore, the flexural strength only decreased by 23% after 100 thermal cycles. The crack growth associated with the thermal fatigue was limited by crack bridging and crack trapping. Hence, the current results suggest that clay/biochar ceramics can be as efficient as molten salts in thermal energy storage with the added benefit of an ease of use in the physical form of bricks. [ABSTRACT FROM AUTHOR]

As electronic device integration and power density increase, materials must have brilliant microwave absorption properties and thermal conductivity to solve electromagnetic wave pollution and thermal management problems. In this work, we attempt to construct core-shell hydroxylated boron nitride nanosheets (BN-OH) @Fe 3 O 4 @PAn (BFeA) nanocomposites by chemical synthesis and in-situ growth design. The excellent magnetic properties of Fe 3 O 4 and the good electrical conductivity of PAn can form magnetic loss and electrical loss centers to play a synergistic effect in improving microwave absorption capacity. Meanwhile, with the wave-transmitting material BN-OH as the core, the electromagnetic waves can be reflected multiple times within the absorber, which further enhances the microwave absorption capability of BFeA. As a result, the minimum reflection loss (RL min) of the composites can reach − 49.85 dB at 11.36 GHz, and the effective microwave absorption bandwidth (RL<−10 dB, EAB) is close to 8 GHz (8.5–16.5 GHz) at a thickness of 3 mm. Simultaneously, to improve the thermal conductivity (TC) of the BFeA and reduce the interfacial thermal resistance, we use hydroxyl and dopamine as the interface linking agent at the interfaces of BN-OH and Fe 3 O 4 , and Fe 3 O 4 and PAn, respectively. In this case, the TC of BFeA-2 reaches 0.98 W (m K)−1 at a total BN–OH content of only 13 wt. %, nearly 4 times that of the raw material (Fe 3 O 4). This work can provide a reference for developing materials with dual functions of thermal management and microwave absorption. [Display omitted] • The core-shell BN-OH@Fe 3 O 4 @PAn nanocomposite with dual functions was prepared. • The RL min of the composites can reach − 49.85 dB, and the EAB is close to 8 GHz. • The thermal conductivity of BN-OH@Fe 3 O 4 @PAn reaches 0.98 W (m K)−1 at a total BN-OH content of only 13 wt. %. [ABSTRACT FROM AUTHOR]

A microwave absorbing composite material with good thermal conductivity has been prepared to solve the problem of electromagnetic wave pollution in high-power density electronic equipment without increasing the heat load of the equipment. Herein, we prepared the quaternary absorbing material hydroxylated boron nitride nanosheets (BN-o)/reduced graphene oxide (r-GO) @Fe 3 O 4 @polyaniline (PAn) (BCFA) and adjusted the content of PAn to enhance the impedance matching and modulate the microwave absorption effect. At a PAn content of 40 wt%, the absorber exhibits admirable microwave absorption performance, the lowest reflection loss (RLmin) of −54.72 dB and effective microwave absorption bandwidth (RL < −10 dB, EAB) of 3.12 GHz at a thickness and frequency of 3.5 mm and 7.2 GHz, respectively. The excellent microwave absorption is due to a suitable mechanism of dielectric and magnetic losses and the excellent impedance matching of the absorber. Moreover, the high thermal conductivity and phonon transport properties of the BN-o/r-GO van der Waals heterostructure give the composite thermal conductivity of 1.69 W(m·K)−1 when the BN-o/r-GO content is approximately 14 wt%. Therefore, BCFA has become a candidate material to solve the electromagnetic pollution problem of high-power density electronic equipment. [Display omitted] • The research highlights of this paper are list below: • The core-shell BN-o/r-GO@Fe 3 O 4 @PAn nanocomposite with dual functions was prepared. • The RL min of the BN-o/r-GO@Fe 3 O 4 @PAn can reach −54.72 dB, and the EAB is close to 3.12 GHz. • The thermal conductivity of BN-o/r-GO@Fe 3 O 4 @PAn reaches 1.69 W(m·K)−1 when the BN-o/r-GO content is approximately 14 wt%. [ABSTRACT FROM AUTHOR]

This work deals with the synthesis, crystallization and the polymorphic interpretation of 2-{3-[3-cyano-6-methyl-2-oxo-4-phenylpyridin-1(2H)-yl]propoxy}-4-methyl-6-phenylnicotinonitrile (2). The quantitative analysis of the two polymorphs has been achieved through single crystal X-ray diffraction and Hirshfeld surface analysis. However, differential scanning calorimetry has been performed to determine the thermal stability and density functional theory to interpret the conformation on the propylene linker. Furthermore, the binding affinity of compound 2 was evaluated through a docking study in the COX-2 active site. An in vivo study revealed significant anti-inflammatory activity. Moreover, solubility of both polymorphs was checked in a 50% MeOH–water mixture and phosphate buffer (pH = 7.40). [ABSTRACT FROM AUTHOR]

In this report, we have measured electroluminescence (El), current-voltage, and effective carrier lifetime characteristics in a InGaN/Sapphire purple light emitting diode (UV3TZ-395-15) in the temperature range from 350 K to 77 K. The semiconductor rate equations have been employed to analyse the light-current data to determine the relation of radiative efficiency ( η) of the device with injection current at different temperatures, which is found to reach nearly 100% at 77 K with 20 mA current. The same analysis simultaneously leads to an evaluation of the non-radiative carrier lifetime ( τ) of the device and its temperature dependence. Next, using the data on voltage gradient obtained from the open circuit voltage decay (OCVD) process, as well as those of ideality factor from the current-voltage characteristics, measurement the variations of the effective carrier lifetime ( τ) with injection current at different temperatures have been evaluated. From the values of τ and τ , we have calculated the temperature dependence of the radiative lifetime ( τ) of carriers. Using the values of lifetimes it is shown that the internal quantum efficiency ( η) of the diode increases with lowering of temperature and reaches its maximum at about 120 K. Finally, this comprehensive study, apart from being highly useful in various optoelectronic applications, contributes to clarify our understanding of the physical processes at work in the device. [ABSTRACT FROM AUTHOR]

This article presents the design and the heat transfer study in a novel adsorbent bed with compound parabolic concentrator (CPC) for solar adsorption chillers. The objectives of the study were to investigate the heat transfer in the adsorbent bed experimentally, and to verify the fins layout through finite-element analysis (FEA) simulation. CPCs with different concentration ratios were experimentally tested and an appropriate design of CPC was selected for a prototype. The prototype was designed with the objective of improving the heat and mass transfer ability of the adsorbent bed. Fins were placed in the transverse direction under the receiver area of each CPC. Spaces were provided from three sides of the adsorbent for easy movement of the refrigerant. FEA software was used to study the effect of the fins layout and fins pitch. The experimental results showed that the heat was efficiently transferring up to the end and extended parts of the bed. Simulation results indicated that the present strategy of placing the fins in a transverse direction gives uniform heat distribution compared to a fins layout with fins placed in a longitudinal direction. The proposed design scheme will be helpful to improve the system performance by increasing the heat and mass transfer ability of an adsorbent bed. [ABSTRACT FROM AUTHOR]

For the development of a high-performance heat exchanger using small channels or minichannels for air-conditioning systems, it is necessary to clarify the characteristics of vapor‐liquid two-phase flow and heat transfer of refrigerants in small-diameter tubes. In this keynote paper, the related research works that have already been performed by the author and coworkers are introduced. Based on the observations and experiments of R410A flowing in small-diameter circular and noncircular tubes with hydraulic diameter of about 1 mm, the characteristics of vapor‐liquid two-phase flow pattern and boiling heat transfer were clarified. In low quality or mass flux and low heat flux condition, in which the flow was mainly slug, the “liquid film conduction evaporation” heat transfer peculiar to small-diameter tubes prevailed and exhibited considerably good heat transfer compared to nucleate boiling and forced convection evaporation heat transfer. The effects of the tube cross-sectional shape and flow direction on the heat transfer primarily appeared in the region of the “liquid film conduction evaporation” heat transfer. A new heat transfer correlation considering all of three contributions has been developed for small circular tubes. [ABSTRACT FROM AUTHOR]

In this paper, we reported on the synthesis, characterization, and the oil-absorbing properties of biomorphic MgAl Layered Double Oxide/acrylic ester resin by combining the biological template method and suspension polymerization method. The biomorphic MgAl Layered Double Oxides (LDO) were prepared by template-directed synthesis employing cotton fibers as templates. Then, oil-absorbing LDO/acrylic ester resin composites were synthesized by suspension polymerization in the presence of functional coupling agents. The oil-absorbing properties and thermal stability of as-synthesized composites were evaluated intensively as well. The morphology and structure of polymer-matrix composites were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. Both acrylic ester resin and composite resin were used in the absorption of organics. The results indicated that oil-absorbing properties and thermal stability of polymer-matrix composites were improved significantly due to the nanocomposites with low particle content which the physico-chemical properties were superior to the pristine polymer. The composites showed excellent stability over 5 cycles of use and regeneration without significant decrease in the oil absorption. These results suggested that the oil absorbents may potentially be useful as next-generation oil absorbent materials for the remediation of the maritime ecosystem in the wake of a massive oil spill. [ABSTRACT FROM AUTHOR]

The foams glass whose porosity is very important, are counted among the new glass products that meet certain desired comfort needs in the particular building area (thermal and acoustic insulation). The objective of this study is to determine the influence of the carbon fibers addition influence on the porosity, the thermal insulation and dielectric loss of foams glass prepared by sintering at 800 °C, which opens the way to foam glass many possibilities for industrial to extend their opportunities that are very varied from thermal insulation to electromagnetic waves absorption. The carbon fibers addition used for this study is 1, 2, 3.5 and 5 wt% in relation to the foam glass load. Physico-chemical analysis techniques such as SEM-EDS, porosity, thermal insulation, differential thermal analysis, and dielectric tests have been used for the foams glass characterization. The obtained microstructure results clearly show that the 5 wt% carbon fibers addition increases the foam glass porosity which leads to low thermal conductivity ( λ =0.0281 W/m°C) and increases its thermal insulating capacity. Furthermore the specific dielectric properties as real permittivity ( ɛ ʹ=2.7619) and high dielectric loss (tan δ =0.02969) favor the use of these glass filled foams with carbon fibers in the electromagnetic waves microwave absorption in the weakest working frequencies (mobile phones and Wi-Fi). [ABSTRACT FROM AUTHOR]

Reversible luminescence modulation upon photochromic reactions with excellent reproducibility was achieved from Eu3+ doped Bi2.5Na0.5Nb2O9 multifunctional ferroelectrics. The material exhibits strong sensitivity to visible light or sunlight with fast response time without inducing any structural changes. [ABSTRACT FROM AUTHOR]

In this study, the altered morphology, amylose content, microstructure, viscosity, and thermal properties of potato starch after being modified for different times (5, 10, 15, 20 and 30 mins) by radio frequency electromagnetic wave (RF) were studied. Obtained the most suitable RF modified time for 3D printing. The results showed that the RF treatment roughened the starch surface and reduced the amylose content, viscosity and pasting temperature of the starch. RF-treated starch gels displayed better print performance than untreated potato gels. Furthermore, RF-20 treatment offers better morphology indexes including clarity and the highest stack height, line uniformity and height retention of printed samples due to the fact that the RF treatment rearranges the internal structure of the potato starch granules, making the internal structure more stable and orderly. Overall, the RF treatment is an effective way to modify starch and optimize starch gels for 3D printing. • Radio frequency electromagnetic wave can modify the potato starch properties. • Radio frequency electromagnetic wave reduced the amylose content of potato starch. • Radio frequency electromagnetic wave reduced the peak viscosity of the starch. • The starches were made into gels for 3D printing. • Radio frequency electromagnetic wave treated for 20 min starch was suited for 3D printing. [ABSTRACT FROM AUTHOR]

InGaN light-emitting diodes (LEDs) with InGaN-GaN quantum barriers of gradually decreasing indium concentration along the growth direction are proposed to be used. In the proposed structure, simulation results show that the holes are widely distributed in the active region due to the larger hole injection/transportation efficiency by reducing the effective potential height for holes and the radiative recombination rate is efficiently improved, which leads to the significant enhancement of light-output power and internal quantum efficiency (IQE) over the conventional LED with GaN barriers. Moreover, the optical performance is further improved when the graded InGaN/GaN supperlattice (SL) is introduced between the multiple quantum wells (MQWs) and p-AlGaN electron blocking layer (EBL) in our designed LED structure, permitting more freedom for the optimization. [ABSTRACT FROM AUTHOR]

The structure of a thermochemical plume conduit rising from the core-mantle boundary and reaching the maximal height when its rising (melting of a plume conduit) terminates is considered in this paper. The relative thermal power of plumes not reaching the surface is Ka < 1.15, and they are called plumes of low thermal power. The dependences of the rate of rising of a ball-like roof of the plume and the rate of rising of day surface above the plume on time are presented. Due to the influence of superlithostatic pressure on the plume roof, the day surface rises above the plume. The elevation of the day surface formed above the plume was calculated for various times in dependence on the horizontal coordinate. With decreasing viscosity of the lithosphere above the plume roof and depth of the plume roof, the rate of rising of the day surface increases, and the time necessary for reaching of the maximal surface elevation decreases. The maximal elevation of the highland above the plume was estimated. The surface elevations formed under the influence of two or three plumes that did not reach the surface were estimated for various times. Based on the suggested model of the formation of elevations above the plume, it is concluded that large highlands (mountain ridges and plateaus) can be formed under the influence of plume clusters that do not reach the day surface. The estimates of the rate of rising of the day surface above the plume obtained in this study are in a good agreement with the geological data on the rates of rising of Tibet and the Caucasus. The rising of a temperature front above the plume roof reaching the maximal rising height is considered. The dependences of the height and rate of rising of a temperature front above the plume roof on time were obtained. The local increase of a specific heat flux in the highland formed above the plume may show that the maximal height of rising of a surface above the plume was gained. Based on the analysis of the heat transfer, the association between the activity of plume clusters that do not reach the surface and the formation of hot fields is suggested. [ABSTRACT FROM AUTHOR]

The hygrothermal properties related to rockwool insulation material structure with different additives are presented using rockwool insulation products obtained from row material of southern Serbia (Vranje region) in the wide range of reference temperatures (10 °C to 70 °C). The hygrothermal properties of basic sample (without additives) are compared to two samples with different additives for two sets of rockwool insulation samples namely: light-soft-panels with density of 50 kg/m3, and middle-weight-panels with density of 80 kg/m3. It is shown that there is significant (approximately 10%) improvement of thermal conductivity for additives based on zeolite. Also, correlation of thermal conductivity and sorption properties of selected samples are presented. [ABSTRACT FROM AUTHOR]

An experimental investigation has been carried out to study the heat transfer and friction factor characteristics of a V-down-perforated baffled roughened solar air heater duct. The roughened wall was uniformly heated and the rest three walls of the duct were kept insulated. Measurements have been carried out for the duct aspect ratio of 10, Reynolds number range of 3800–19,000, relative hole position range of 0.429–0.571, relative roughness pitch range of 2–4, and open area ratio range of 12–44%. The relative roughness height of 0.4 and angle of attack of 60° are kept constant during the entire experimentation. The heat transfer and friction factor data obtained were compared with the data obtained from a smooth duct under similar operating conditions. In comparison to the smooth duct the V-shaped perforated baffle roughened duct enhanced the Nusselt number and friction factor by 2.57 and 5.96 times, respectively. The thermohydraulic performance parameter is found superior for the open area ratio of 24% and relative roughness pitch of 2.5. [ABSTRACT FROM PUBLISHER]

A ground source heat pump assisted by an array of photovoltaic (PV)-thermal modules was studied in this work. Extracting heat from an array of PV modules should improve the performance of both the PV cells and the heat pump. A series of computer simulations compare the performance of a ground source heat pump with a short ground circuit, used to provide space heating and domestic hot water at a house in southern England. The results indicate that extracting heat from an array of PV-thermal modules would improve the performance of a ground source heat pump with an undersized ground loop. Nevertheless, open air thermal collectors could be more effective, especially during winter. In one model more electricity was saved in ohmic heating than was generated by cooling the PV cells. Cooling the PV modules was found to increase their electrical output up to 4%, but much of the extra electricity was consumed by the cooling pumps. [ABSTRACT FROM AUTHOR]

This paper presents a solution to an inhomogeneous problem of electromagnetic wave propagation through a functionally graded wave-absorbing (FGWA) infinite thin plate. The FGWA plate compounded by dielectric and magnetic materials has an arbitrary inhomogeneity through its thickness. The characteristics of the electromagnetic wave absorption and the temperature field due to the heat energy arising from electromagnetic wave absorption in the plate are analyzed. The results demonstrate that the electromagnetic wave absorption properties have been significantly improved for the gradient absorbing plate in comparison with the homogeneous one. With the proper gradient distribution design of material properties, the FGWA plate shows good performance on the lower reflection and high absorption. [ABSTRACT FROM AUTHOR]

Surface temperature measurements within sliding contacts are useful since interfacial heat dissipation is closely linked to tribological behavior. One of the most powerful techniques for such measurements is in-contact temperature mapping whereby a sliding contact is located beneath an infrared microscope. In this approach, one of the specimens must be transparent to infrared and coated such that radiation components can be distinguished and isolated from background values. Despite its effectiveness, a number of practical constraints prevent this technique from being applied to rough surfaces--a research area where temperature maps could provide much needed two-dimension input data to inform mixed and boundary friction models. The research described in this paper is aimed at improving the infrared temperature mapping technique in terms of validity, robustness, and spatial resolution, so that measurements of rough surfaces contacts can be made. First, Planck's law is applied in order to validate the use of surface coating as a means of removing background radiation. Second, a refined method of calibration is put forward and tested, which negates the need for a soft aluminum coating and hence enables rough surfaces to be measured. Finally, the use of super-resolution algorithms is assessed in order extend spatial resolution beyond the current limit of 6 µm. [ABSTRACT FROM AUTHOR]

The aim of this study is to prepare and characterize foliated graphite nanosheets (FGNs) reinforced composites based on epoxy resin for the electromagnetic wave shielding and microwave absorbing applications. The microstructure of as prepared FGNs and epoxy reinforced with different content of foliated graphite was examined by means of scanning electron microscopy and transmission electron microscopy. The effect of FGNs on thermal stability of composites was examined by thermal gravimetric. It is found that the inclusion of FGNs into the epoxy resin matrix enhances the microstructure core of epoxy resin composites. Static electric properties such as electrical conductivity, carrier mobility, number of charge carriers, and thermoelectric power of composites were studied in details. Dielectric properties of epoxy/FGN composites were characterized as a function of composition and frequency in the range of 1-18 GHz. The electromagnetic wave shielding as a function of frequency of composites was examined and compared with theoretical values. The highest shielding effectiveness was obtained for high foliated graphite loading sample FG40 at frequency of 18 GHz it equals to 62 dB. Finally, the electromagnetic wave properties such as absorption loss and reflection loss as a function of frequency were investigated. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

We have investigated the photoresponsive behavior of homogeneously aligned low-azobenzene-concentration crosslinked liquid-crystalline polymers. We compared the thermal contraction and photocontraction of the films, and show that upon UV irradiation, they bend efficiently towards the actinic light source. The photoinduced bending is studied both under continuous-wave irradiation and irradiation with nanosecond pulses. Pulsed irradiation revealed that the photomechanical response can take place within sub-millisecond time scale, and that even a single laser pulse can cause the sample to bend. [ABSTRACT FROM AUTHOR]

We have observed a gas of Fermi atoms confined in the antinodes of a standing electromagnetic wave. The standing wave is formed by two counter-propagating beams with the wavelength of 10.6 μm focused on the same spot. Each antinode confines a pancake-shaped cloud of 7500 lithium-6 atoms in two equally populated spin states at the temperature T = 0.1 EF, where EF is the Fermi energy. The system is in the regime beyond the local density approximation: Only the 3 lowest energy states of the axial motion are populated. The system may become an instrument for the study of 2D Fermi physics and 3D effects beyond the local density approximation. [ABSTRACT FROM AUTHOR]

Abstract: Deposited layers in the JET MKII-HD outer divertor have been investigated on the basis of their transient heating. The Planck radiation in the 400–600nm wavelength range and IR thermography data were analyzed to correlate the appearance of the layers with plasma conditions. Both methods yielded significantly different surface temperatures: typically >2000K for the visible light spectroscopy and down to 800K for the thermography. This is explained by the existence of high temperature emission areas as small as 1–2mm2. Analysis of the reoccurrence of hot spots in the outer divertor throughout the 2006 campaigns indicated that the formation is determined by the combination of the outer strike point location and the plasma stored energy. The observations did not indicate any changes in thermal properties nor cyclic formation and disintegration of the layers, i.e. it was stable and so-called hard layers. [Copyright &y& Elsevier]

Abstract: Al90Sm10, a marginal glass former, was rapidly solidified using Cu-block single roller melt spinning at wheel speeds of 30 and 40m/s. The product phases of rapid solidification were identified and analyzed using high energy synchrotron X-ray diffraction (HEXRD), high resolution transmission electron microscopy, and atom probe tomography. The as-quenched structure consists of a saturated amorphous phase and nanocrystalline Al with typical length scale of about 5nm. The appearance of a pre-peak on HEXRD diffraction patterns and a low activation energy for first crystallization as determined using the Kissinger and Ozawa methods indicate some local ordering in the amorphous phase. The devitrification phase transformation path was determined using in situ high energy synchrotron radiation. Three phases, MS1, H1, and Al4Sm, were identified during decomposition of the amorphous phase. MS1, H1 and Al4Sm are cubic, hexagonal and orthorhombic metastable phases, respectively. [Copyright &y& Elsevier]

Radiosity-Graphics combined Model (RGM) has been proposed to calculate the radiation regime and bidirectional reflectance distribution function of complex 3-D scene, which is limited in visible and near-infrared wavelength (0.3-3 μm) region. In this paper, RGM is extended to thermal region (named as TRGM) based on thermal-radiosity theory and thermal-emission directionality of vegetation canopy. The TRGM has been implemented on Microsoft Windows platform, and a parameterization scheme for crop canopies is introduced in this paper. It is then evaluated by comparing with two row-crop directional thermal emission models and one thermal radiative-transfer model. Field experiment data has been used to validate the TRGM for row structural wheat and maize canopies. The root mean square error of directional brightness temperature (DBT) is smaller than 1.0 °C for the wheat canopy and 0.5 °C for the maize canopy while the canopy DBTs vary more than 4 °C. Model sensitivity analyses have also been conducted to illustrate influences of component temperature distribution, component emissivity, incident atmospheric radiation, and canopy structure on the crop canopy DBT. [ABSTRACT FROM AUTHOR]

An algorithmic technique is presented that allows estimation of maximum temperature rise in a thermal model with component-board thermal interaction. The technique is based on a generalized thermal port grouping to estimate the interface temperature profile derived from coarse port assignments. By using a very simple environment, it takes a library-type thermal component model with many thermal ports included and transforms it by grouping thermal ports based on a temperature profile, allowing a minimal number of port groups to provide the same accuracy as the original model in a shorter time. The usefulness of this technique is illustrated through simulation of two thermal models with extreme nonuniform temperature distribution on the interface surface. The prediction accuracy is evaluated by comparison with the final solutions to numerical simulation. [ABSTRACT FROM AUTHOR]

Abstract: The radiation curing of an epoxy monomer in the presence of an iodonium salt, as photo initiator, is studied. Systems with different concentrations of photo initiators have been polymerized via both gamma rays and e-beam, at various dose rates. The aim of this work is to investigate how the photo initiator concentration and the irradiation dose rate affect the temperature of the systems during curing and how the different thermal histories influence the dynamic mechanical thermal properties of the obtained materials. [Copyright &y& Elsevier]

The elastic properties and thermal behavior of synthetic zincochromite (ZnCr2O4) have been studied by combining room-temperature high-pressure (0.0001-21 GPa) synchrotron radiation powder diffraction data with high-temperature (298-1240 K) powder diffraction data. Elastic properties were obtained by fitting two Equations of State (EoS) to the P-V data. A third-order Birch-Murnaghan model, which provides results consistent with those from the Vinet EoS, yields: K0 = 183.1 (+3.5) GPa, K' = 7.9(±0.6), K" = -0.1278 Gpa-1 (implied value), at V0 = 577.8221 Å (fixed). Zincochromite does not exhibit order-disorder reactions at high temperature in the thermal range explored, in agreement with previous studies. The volume thermal expansion was modeled with αv = α0 + α1T + α2/T-2, where only the first coefficient was found to be significant [α0 = 23.0(4) 10-6 K-1]. Above 23 GPa diffraction patterns hint at the onset of a phase transition; the high pressure phase is observed at approximately 30 GPa and exhibits orthorhombic symmetry. The elastic and thermal properties of zincochromite were then used to model by thermodynamic calculations the P-T stability field of ZnCr2O4 with respect to its oxide constituents (Cr2O3 and rocksalt-like ZnO). Spinel is expected to decompose into oxides at about 18 GPa and room temperature, in absence of sluggish kinetics. [ABSTRACT FROM AUTHOR]

A simple and fast micellar electrokinetic chromatographic (MEKC) method for the determination of five main compounds (hydroquinone, metol, phenidone, 2-hydroxy-5-methylaminobenzenesulphonate and 2,5-dihydroxybenzenesulphonate) in X-ray film developing solutions was developed. The optimal conditions for the separation were established by varying the concentration of sodium dodecyl sulfate (SDS), the electrolyte pH and the temperature. Successful results were obtained with a 25?mmol?L-1 Tris-phosphate buffer at pH 9.0 in the presence of 50?mmol?L-1 SDS using direct UV detection at 214?nm. Under these conditions, baseline separation of the five compounds was achieved in less than 8?min. The method was validated in terms of precision, linearity, accuracy, and successfully applied to the analysis of X-ray film developing baths. [ABSTRACT FROM AUTHOR]

Eclosion rhythm of the high-altitude Himalayan strain of Drosophila ananassae from Badrinath (altitude 5123 m) was temperature-dependent and at 21°C, it was entrained by cycles of 12 h light: 12 h darkness (LD 12:12) and free-ran in constant darkness, however, it was arrhythmic at 13°C or 17°C under identical experimental conditions (Khare, P. V., Barnabas, R. J., Kanojiya, M., Kulkarni, A. D., Joshi, D. S. (2002). Temperature dependent eclosion rhythmicity in the high altitude Himalayan strains of Drosophila ananassae. Chronobiol. Int. 19:1041–1052). The present studies were designed to see whether or not these strains could be entrained at 13°C, 17°C, and 21°C by two types of LD cycles in which the photoperiod at 100 lux intensity varied from 6 h to 18 h, and the light intensity of LD 14:10 cycles varied from 0.001 lux to 1000 lux. All LD cycles entrained this strain at 21°C but not at 13°C or 17°C. These results demonstrate that the entrainment of eclosion rhythm depends on the ambient temperature and not on the photoperiod or light intensity of LD cycles. Thus the temperature has taken precedence over the light in the entrainment process of eclosion rhythm of the high altitude Himalayan strain of D. ananassae. This may be the result of natural selection in response to the environmental temperature at Badrinath that resembles that of the sub-Arctic region but the photoperiod or light intensity are of the subtropical region. [ABSTRACT FROM AUTHOR]

With the rapid development of electronic technology and the integration of electronic chips, electromagnetic wave pollution and thermal management have become two critical issues hindering the growth of electronic equipment. In this work, an effective strategy has been developed for the synthesis of well-designed core-shell layered structures with hydroxylated boron nitride (HO-BNNS) core and Fe 3 O 4 shell. The as-prepared HO-BNNS@Fe 3 O 4 composites have both microwave absorption and thermal management properties. Moreover, these two performances show a synergistic effect. It is worth noting that the minimum reflection loss (RL min) of HO-BNNS@Fe 3 O 4 composite materials are −45.31 dB at 8.64 GHz with a thickness of 2 mm. Additionally, the thermal conductivity of HO-BNNS@Fe 3 O 4 composites are 1.75 W m−1K−1 at an HO-BNNS weight of 30%, which increases approximately 400% than the initial Fe 3 O 4. These comprehensive properties of HO-BNNS@Fe 3 O 4 composites make it have potential applications in the field of electronic equipment packaging. Image 1 The highlights of this paper are list below: ● An effective strategy has been developed for the synthesis of well-designed core-shell layered structures with hydroxylated boron nitride (HO-BNNS) core and Fe 3 O 4 shell. ● The as-prepared HO-BNNS@Fe 3 O 4 composites have both microwave absorption and thermal management properties. ● The microwave absorption and thermal management performance of the HO-BNNS@Fe 3 O 4 composites show a synergistic effect. [ABSTRACT FROM AUTHOR]

Thermal process of 1064 nm millisecond pulsed Nd:YAG laser irradiated silicon was time-resolved temperature measured by an infrared radiation pyrometer, temperature evolutions of the spot center for wide range of laser energy densities were presented. The waveforms of temperature evolution curves contained much information about phase change, melting, solidification and vaporization. An axisymmetric numerical model was established for millisecond laser heating silicon. The transient temperature fields were obtained by using the finite element method. The numerical results of temperature evolutions of the spot center are in good agreement with the experimental results. Furthermore, the axial temperature distributions of the numerical results give a better understanding of the waveforms in the experimental results. The melting threshold, vaporizing threshold, melting duration, and melting depth were better identified by analyzing two kinds of results. [ABSTRACT FROM AUTHOR]

The specific heat of high quality LaNB6 (N = 10, 11, natural) single crystals is investigated in a wide range of temperatures 2 - 300 K. The obtained data allow to estimate correctly (i) the electronic γ ·T term of specific heat (γ ≈ 2.4 mJ/(mol·K2)), (ii) the contribution from quasilocal vibrating mode of La3+ ions (θE ≈ 150 - 152 K), (iii) the Debye-type term from rigid boron cages (θD ≈ 1160 ± 40 K). Our data also suggest an additional defect-mode component (iv) which may be attributed to a contribution of 1.5% boron vacancies in LaB6. The obtained results may be interpreted in terms of formation of two level systems, which appear when La3+ ions are displaced from their centrosymmetric positions in the cavities of rigid boron cages, apart from randomly distributed boron vacancies in the LaB6 matrix. [ABSTRACT FROM AUTHOR]

The specific heat of high quality LaNB6 (N = 10, 11, natural) single crystals is investigated in a wide range of temperatures 2 - 300 K. The obtained data allow to estimate correctly (i) the electronic γ ·T term of specific heat (γ ≈ 2.4 mJ/(mol·K2)), (ii) the contribution from quasilocal vibrating mode of La3+ ions (θE ≈ 150 - 152 K), (iii) the Debye-type term from rigid boron cages (θD ≈ 1160 ± 40 K). Our data also suggest an additional defect-mode component (iv) which may be attributed to a contribution of 1.5% boron vacancies in LaB6. The obtained results may be interpreted in terms of formation of two level systems, which appear when La3+ ions are displaced from their centrosymmetric positions in the cavities of rigid boron cages, apart from randomly distributed boron vacancies in the LaB6 matrix. [ABSTRACT FROM AUTHOR]

The study of relaxational behavior of multicomponent metallic liquids still holds the key to understanding and improving the glass-forming abilities of bulk metallic glasses. Herein, we report measurements of the collective relaxation times in a melted bulk metallic glass (LM601Zr51Cu36Ni4Al9) in the kinetic regime (Q: 1.5-4.0Å-1) using quasielastic neutron scattering. The results reveal an unusual slope change in the Angell plots of the collective relaxation time of this metallic liquid around 950°C, beyond the melting point of the material. Specific heat capacity measurement also reveals the presence of a peak around the same temperature. The coincidence is rationalized using Adams-Gibbs theory, and motivates more careful experimental and computational studies of the metallic liquids in the future. [ABSTRACT FROM AUTHOR]

Technical issues surrounding the use of nanoindentation at elevated temperatures are discussed, including heat management, thermal equilibration, instrumental drift, and temperature-induced changes to the shape and properties of the indenter tip. After characterizing and managing these complexities, quantitative mechanical property measurements were performed on a specimen of standard fused silica at temperatures up to 405 °C. The extracted values of hardness and Young's modulus were validated against independent experimental data from conventional mechanical tests, and accuracy comparable to that obtained in standard room-temperature nanoindentation is demonstrated. In situ contact-mode images of the surface at temperature are also presented. [ABSTRACT FROM AUTHOR]