The graphene film with high thermal conductivity has garnered considerable attention in recent years as an ideal material for dissipating heat in high-power electronic devices. Thermal conductivity is a crucial parame...
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The graphene film with high thermal conductivity has garnered considerable attention in recent years as an ideal material for dissipating heat in high-power electronic devices. Thermal conductivity is a crucial parameter for evaluating its fundamental performance. High-precision measurement holds significant importance for understanding its basic properties, fabrication optimization, and industrial applications. However, it is difficult to simultaneously achieve efficient, accurate, and reliable measurements with existing commercial thermal conductivity testing methods. The development of a convenient, high-precision, and reliable measurement approach remains a great challenge. Here, we introduce a thermal conductivity testing methodology with superior accuracy and excellent efficiency based on an improved steady-state electric heating method, refined through the optimization of heat transfer principles, experimental operation, and data analysis, supported by finite element simulation. The accuracy of measurements is affected by four factors: heat loss calibration, sample size, device design, and data treatment. The experimental results show that the heat loss caused by heat radiation and heat convection affects the temperature distribution and the measurements of the sample, which should be strictly controlled by sample size and temperature rise. Reasonable screening and preprocessing of data are also necessary to improve measurement accuracy. Through the comparative analysis of the temperature distribution and thermal conductivity measurements of samples under different conditions, we propose feasible operational guidance and a standardized testing protocol to minimize measurement error. The measurement error is less than 3.0%, and uncertainty is reduced to 0.5%. Simulation results confirm that the response time of this method is down to milliseconds, correlating well with the experiment, which can effectively improve test efficiency. Considering the combined meri
The impression made by a loaded cylindrical flat-end punch on a polymer surface was observed to disappear with time at the same temperature after the load was removed. The depth-time relation appeared to obey second o...
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The impression made by a loaded cylindrical flat-end punch on a polymer surface was observed to disappear with time at the same temperature after the load was removed. The depth-time relation appeared to obey second order kinetics. The temperature dependence of the rate constant shows two consecutive processes with activation energies, 906 kJ/mole (between 143 and 147 degrees C) and 91 kJ/mole (between 150 and 160 degrees C) for PC (Tg is at about 146 degrees C) and 440 kJ/mole (between 104 and 110 degrees C) and 95 kJ/mole (between 115 and 140 degrees C) for PMMA (Tg is at about 112 degrees C). These activation energies are probably associated with the motion and annihilation of conformational or structural defects of opposite signs. This kind of shape memory phenomena may be general for all amorphous polymers.
Cellulose, owing to its abundant natural availability and excellent mechanical properties, is considered an ideal alternative to petroleum-based polymers in the fabrication of piezoelectric nanogenerators (PENGs). In ...
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The microstructural features of high-temperature sintered and CaO-MgO-Al_2O_3-SiO_2(CMAS) corroded air plasma sprayed Y_2O_3 stabilized ZrO_2(YSZ) thermal barrier coatings(TBCs) under the thermal gradient condition we...
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The microstructural features of high-temperature sintered and CaO-MgO-Al_2O_3-SiO_2(CMAS) corroded air plasma sprayed Y_2O_3 stabilized ZrO_2(YSZ) thermal barrier coatings(TBCs) under the thermal gradient condition were comparatively studied. As-sprayed YSZ has a lamellar structure and the lamellae are composed of closely aligned columnar crystals. The sintered and the CMAS corroded YSZ coatings maintain the t'-ZrO_2 phase as the as-sprayed YSZ coating. The sintered YSZ remains the lamellar structure with reduced interlamellar gaps and grains coarsening. After the CMAS corrosion, the top layer of the YSZ coating keeps its lamellar structure consisting of some columnar grains with the CMAS infiltration into the intergrain gaps and the formation of striped Zr_2Y_2 O_7. The typical lamellar structure transforms into more equiaxed grains in the middle and bottom layers of the ceramic coating along with significant infiltration of amorphous CMAS and anorthite formation in the bottom layer owing to the high contents of Ca and Al.
Relying on the anharmonic special displacement method, we introduce an ab initio quasistatic polymorphous framework to describe local disorder, anharmonicity, and electron-phonon coupling in superionic conductors. Usi...
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Rare earth chalcogenides provide a great platform to study exotic quantum phenomena such as superconductivity and charge density waves. Among various interesting properties, the coupling between magnetism and electron...
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Over 5000 years of development, the functions of clothing have been mainly limited in warmth and modesty. With the development of smart fibers, fabrics are anticipated to revolutionize multidisciplinary applications, ...
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Over 5000 years of development, the functions of clothing have been mainly limited in warmth and modesty. With the development of smart fibers, fabrics are anticipated to revolutionize multidisciplinary applications, such as smart healthcare and the Internet of Things [1–4].
Improved hybrid solar cells consisting of vertical aligned cadmium sulfide （CdS） nanorod arrays and interpenetrating polythiophene （P3HT） have been achieved via modification of CdS nanorod surface by using conjuga...
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Improved hybrid solar cells consisting of vertical aligned cadmium sulfide （CdS） nanorod arrays and interpenetrating polythiophene （P3HT） have been achieved via modification of CdS nanorod surface by using conjugated N719 dye. The complete infiltration of P3HT between CdS nanorods interspacing was verified by scanning electron microscopy. By employing absorption and photoluminescence spectra, and current-voltage characterization the interaction between N719 molecules and CdS nanorods/P3HT interface was explored, and the role of N719 dye on the improvement of device performance was discussed.
Two-dimensional(2D)nanomaterials have attracted a great deal of attention since the discovery of graphene in 2004,due to their intriguing physicochemical properties and wide-ranging applications in catalysis,energy-re...
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Two-dimensional(2D)nanomaterials have attracted a great deal of attention since the discovery of graphene in 2004,due to their intriguing physicochemical properties and wide-ranging applications in catalysis,energy-related devices,electronics and *** maximize the potential of 2D nanomaterials for their technological applications,controlled assembly of 2D nanobulding blocks into integrated systems is critically *** mini review summarizes the reported strategies of 2D materials-based assembly into integrated functional nanostructures,from in-situ assembly method to post-synthesis *** applications of 2D assembled integrated structures are also covered,especially in the areas of energy,electronics and sensing,and we conclude with discussion on the remaining challenges and potential directions in this emerging field.
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