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Polymer functionalized nanoparticles in liquid crystals: combining PDLCs with LC nanocomposites
摘要： Liquid crystal (LC)–polymer blends are important stimuli responsive materials already employed in a wide range of applications whereas nanoparticle (NP)–LC blends are an emerging class of nanocomposites. Polymer ligands offer the advantages of synthetic simplicity along with chemical and molecular weight tunability. Here we compare the phase behavior of 5CB blended with poly(ethylene oxide) (PEO) and with gold NPs functionalized with thiolated PEO (AuNP–PEO) as a function of PEO concentration by DSC, POM and 13C NMR spectroscopy. Both PEO and the AuNP–PEO form uniform dispersions in isotropic 5CB and phase separate below the I–N phase transition temperature. Above the PEO crystallization temperature, the PEO/5CB blends show the expected biphasic state of PEO rich-isotropic liquid co-existing with PEO-poor nematic droplets. At PEO concentrations above 10 wt%, nematic 5CB nucleates with PEO crystallization. Both PEO and AuNP–PEO induce homeotropic alignment of the 5CB matrix immediately below TNI. The AuNP–PEO/5CB blends form thermally reversible cellular networks similar to AuNPs functionalized with low molecular weight mesogenic ligands. A thermodynamic model to account for the observed phase behavior is presented.
关键词： Polymer blends,Nanoparticles,Liquid crystal,Phase behavior,Thermodynamic model
更新于2025-09-23 15:21:01
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Advance on Single Pressure Refractive Index Gas Thermometry
摘要： A novel single pressure refractive index gas thermometry(SPRIGT) of thermodynamic temperature of helium gas filled in quasi-spherical microwave cavity resonator(QMCR) by combination of microwave measurements, temperature and pressure control. A long-term temperature stability better than 0.2mK is demanded for the QMCR from 5K to 24.5561 K. The uncertainty below 4ppm for pressure needs to precisely control the oscillation of temperature along the gas line. Microwave resonance frequency measurement in QMCR should be better than 2ppb. To meet these requirements, SPRIGT has been built in China and the first run experimental data was analysis in this paper.
关键词： Pressure control,Temperature control,SPRIGT,Thermodynamic temperature,Microwave measurement,QMCR,Primary thermometry
更新于2025-09-23 15:21:01
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Temperature Dependence of the Lattice Parameters of Cu2?–?xSe (0.03 ≤ x ≤ 0.23) Powders Fabricated by Mechanochemical Synthesis
摘要： The Cu2 – xSe (0.03 ≤ x ≤ 0.23) powders fabricated by mechanochemical synthesis have been studied by X-ray diffraction. The in situ study has been carried out for the temperature dependences of the lattice parameters, the structures, and the phase compositions of the powders in the temperature range 25–350°C. The powder compositions are shown to differ from the charge compositions and are shifted to lower copper concentrations. The estimation of peak half-widths of the cubic β phase indicates an increase in the structure imperfection after the phase transition from the α phase to the β phase of Cu2 – xSe at ~140°C. It is shown that the superpositions of the subtraction solutions (copper vacancies) and interstitials solutions (copper atoms in interstitial sites), whose proportion is changed as a function of temperature and the deviation from stoichiometry, are in the thermodynamic equilibrium in the copper selenide solid solution at room temperature. The change in the slope of the dependence of the lattice parameter of the powder Cu2 – xSe samples on the composition (0.03 ≤ x ≤ 0.23) in the temperature range 25–350°C enables the suggestion that interstitial copper atom concentration increases with temperature and deviation from stoichiometry.
关键词： phase transition,lattice parameters,mechanochemical synthesis,Cu2 – xSe,X-ray diffraction,thermodynamic equilibrium
更新于2025-09-23 15:21:01
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[IEEE 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - Berlin, Germany (2019.6.23-2019.6.27)] 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - In-Situ Transmission Electron Microscopy Coupled with Resonant Microcantilever for Comprehensive Evaluating Sulfurization Performance of Zinc Oxide Nanowires
摘要： This paper reports a new technique with in-situ transmission electron microscopy (in-situ TEM) and resonant microcantilever to comprehensively evaluate sulfurization performance of ZnO nanowires. Herein, in-situ TEM is used to real-time observe the sulfurization process of ZnO nanowires under SO2-contained atmosphere. temperature-varying micro-gravimetric method, thermodynamic interaction between ZnO nanowires and SO2 molecules is quantitatively evaluated by resonant microcantilever. By exposing the ZnO nanowires sample to SO2-contained atmosphere, a thick shell layer of ZnSO3 can be formed onto the surface of ZnO nanowires and a novel core-shell nanowire structure of ZnO@ZnSO3 is obtained finally. According to our comprehensive evaluation results, the ZnO nanowires sample with 100 nm diameter exhibits high reactive to SO2 molecules and is suitable for SO2 capture and storage.
关键词： sulfurization process,ZnO nanowires,thermodynamic parameter extraction,In-situ TEM
更新于2025-09-23 15:19:57
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Thermophotonic cooling with light-emitting diodes
摘要： The currently ubiquitous light-emitting diodes (LEDs) have revolutionized the lighting industry. Contrary to common belief, however, LEDs are much more than just simple electricity-to-light converters. They are solid-state thermodynamic machines, theoretically capable of continuous and near-reversible energy conversion between electrical, thermal and optical energy. For over 50 years, the possibility of exploiting LEDs as efficient solid-state coolers has remained largely out of reach due to the high-material-quality requirements and commercial focus on light emission. Recent promising advances in electroluminescent cooling by LEDs, however, suggest that the remaining challenges in the area may be surmountable and practical cooling could be feasible. This Perspective discusses recent achievements in electroluminescent cooling, outlining the expected promise, the remaining challenges and their potential solutions.
关键词： solid-state thermodynamic machines,light-emitting diodes,electroluminescent cooling,LEDs,thermophotonic cooling
更新于2025-09-23 15:19:57
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Modeling radiative-shocks created by lasera??cluster interactions
摘要： Radiative-shocks induced by laser–cluster interactions are modeled using radiation-hydrodynamic simulations. A good agreement—in both shock velocity and density pro?les—is obtained between experiment and simulations, indicating that non-local thermodynamic equilibrium (NLTE) radiative effects are important in the experimental regime examined, particularly at early times ((cid:2)30 ns) due to the elevated temperatures ((cid:3)35 eV). The enhanced NLTE radiative emission causes the shock to be reduced in amplitude, increased in width, and reduced in propagation velocity, while the amplitude of the radiative precursor is increased. As the density and temperature conditions are relatively modest, this potentially has important implications for the scalings that are used in laboratory–astrophysics to transform between laboratory and astrophysical scales, which do not hold for non-LTE systems.
关键词： non-local thermodynamic equilibrium,laboratory–astrophysics,radiation-hydrodynamic simulations,radiative-shocks,laser–cluster interactions
更新于2025-09-23 15:19:57
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Structural and thermodynamic properties of cubic sphalerite aluminum nitride under hydrostatic compression
摘要： The present work aims to investigate the structural phase stability and thermodynamic properties of aluminium nitride with cubic zinc-blende structure at normal and high pressures (up to 5 GPa) and high temperatures (up to 2000 K). In this study, we use the pseudopotential plane wave method within the framework of the density functional theory with the local density approximation for the exchange-correlation functional. The phase transition pressure has been determined and found to be in very good agreement with several theoretical data. The pressure and temperature dependences of thermodynamic properties are successfully presented, analyzed and discussed in details. Besides, the plasmon energy and microhardness are examined.
关键词： High-pressure,Ab-initio calculation,High-temperature,Thermodynamic properties,Aluminium nitride
更新于2025-09-23 15:19:57
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Topics in Present-day Science Technology and Innovation: Ultrafast Relaxation Processes in Semiconductors
摘要： The nowadays notable development of all the modern technology, fundamental for the progress and well being of world society, imposes a great deal of stress in the realm of basic Physics, more precisely on Thermo-Mechanical Statistics. In electronics and optoelectronics we face situations involving physical-chemical systems far-removed-from equilibrium, where ultrafast (in pico- and femto-second scale) and non-linear processes are present. Here we describe in an extended overview the question of ultrafast relaxation processes in the excited plasma in semiconductors.
关键词： nonequilibrium thermodynamic,ultrafast relaxation,semiconductors
更新于2025-09-19 17:15:36
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Thermal properties of high purity zinc-tellurite glasses for fiber-optics
摘要： The thermal properties of the series glasses (TeO2)(0.86-x)(ZnO)x(La2O3)0.04(Na2O)0.1 were studied. The heat capacity and characteristics of transitions between aggregative states were determined by the method of differential scanning calorimetry (DSC) in the temperature range 320-950 K. The experimentally obtained values of thermal conductivity, density and coefficient of thermal expansion at room temperature are as follows: 1.14 ± 0.06 W/(m?K), 5.20 ± 0.02 g/cm3 and (54.6 ± 1.2)?10-6 K-1, respectively. The model-statistical processing of calorimetric data was used to determine the complete set of standard thermodynamic functions together with their approximation to the unexplored low-temperature region by means of parametric similarity. The approach allows predicting the functions for unexplored intermediate glasses compositions.
关键词： heat capacity,thermal conductivity,thermodynamic functions,coefficient of thermal expansion,density,Zinc-tellurite glasses
更新于2025-09-19 17:15:36
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Solar energy harvesting potential of a photovoltaic-thermoelectric cooling and power generation system: Bidirectional modeling and performance optimization
摘要： In the present work, a comprehensive thermodynamic and exergoeconomic comparison between concentrated photovoltaic-thermoelectric cooling (CPV-TEC) and concentrated photovoltaic-thermoelectric generation (CPV-TEG) systems was introduced and explored, aiming to actively investigate the energy harvesting potential of the photoelectric-thermoelectric cooling and power generation processes. Transitional characteristics of thermoelectric conversion in concentrated photovoltaic-thermoelectric hybrid (CPV-TEH) system have been outlined through multiple evaluation indicators, including output electricity, cell temperature, thermodynamic efficiency, exergy destruction and unit exergy cost under various decision parameters. Furthermore, operating mode and conversion conditions of thermoelectric device in CPV-TEH system have been sensitively identified to obtain the dual action mechanism of cooling and power generation sequentially. Theoretical models have been compared and validated well with former published results. Results indicate that the operating mode of thermoelectric device could be fully converted from TEG to TEC when the operating current is around 0.27 A; the minimum unit exergy costs are respectively found to be 0.263 $/kwh, 0.148 $/kwh and 0.113 $/kwh for CPV-TEG system and 0.266 $/kwh, 0.152 $/kwh and 0.118 $/kwh for CPV-TEC system at CG = 1, 2, and 3 kW/m2. Present research may be helpful for the design and optimization of the CPV-TEH system to harvest the thermal and electric energy from the sunlight, thus enhancing its energy conversion efficiency.
关键词： Photovoltaic-thermoelectric system,Refrigeration and power generation,Thermodynamic and exergoeconomic comparisons,Dual action mechanism
更新于2025-09-19 17:13:59