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Bulk heating

Andreas Sousanis, Philippe F Smet, Dirk Poelman
In this review, we give an overview of the properties and applications of samarium monosulfide, SmS, which has gained considerable interest as a switchable material. It shows a pressure-induced phase transition from the semiconducting to the metallic state by polishing, and it switches back to the semiconducting state by heating. The material also shows a magnetic transition, from the paramagnetic state to an antiferromagnetically ordered state. The switching behavior between the semiconducting and metallic states could be exploited in several applications, such as high density optical storage and memory materials, thermovoltaic devices, infrared sensors and more...
August 16, 2017: Materials
Shanshan Wang, Hidetaka Sawada, Qu Chen, Grace G D Han, Christopher Allen, Angus I Kirkland, Jamie H Warner
Pt-nanocrystal:MoS2 hybrid materials have promising catalytic properties for hydrogen evolution, and understanding their detailed structures at the atomic scale is crucial to further development. Here, we use an in situ heating holder in an aberration-corrected transmission electron microscope to study the formation of Pt nanocrystals directly on the surface of monolayer MoS2 from a precursor on heating to 800 °C. Isolated single Pt atoms and small nanoclusters are observed after in situ heating, with two types of preferential alignment between the Pt nanocrystals and the underlying monolayer MoS2...
August 14, 2017: ACS Nano
Ling Shao, Amit Datye, Jiankang Huang, Jittisa Ketkaew, Sung Woo Sohn, Shaofan Zhao, Sujun Wu, Yuming Zhang, Udo D Schwarz, Jan Schroers
We used pulsed laser beam welding method to join Pd43Cu27Ni10P20 (at.%) bulk metallic glass and characterized the properties of the joint. Fusion zone and heat-affected zone in the weld joint can be maintained completely amorphous as confirmed by X-ray diffraction and differential scanning calorimetry. No visible defects were observed in the weld joint. Nanoindentation and bend tests were carried out to determine the mechanical properties of the weld joint. Fusion zone and heat-affected zone exhibit very similar elastic moduli and hardness when compared to the base material, and the weld joint shows high ductility in bending which is accomplished through the operation of multiple shear bands...
August 11, 2017: Scientific Reports
Marek Kostecki, Jarosław Woźniak, Tomasz Cygan, Mateusz Petrus, Andrzej Olszyna
Self-lubricating composites are designed to obtain materials that reduce energy consumption, improve heat dissipation between moving bodies, and eliminate the need for external lubricants. The use of a solid lubricant in bulk composite material always involves a significant reduction in its mechanical properties, which is usually not an optimal solution. The growing interest in multilayer graphene (MLG), characterised by interesting properties as a component of composites, encouraged the authors to use it as an alternative solid lubricant in aluminium matrix composites instead of graphite...
August 10, 2017: Materials
Adam Hultqvist, Kerttu Aitola, Kári Sveinbjörnsson, Zahra Saki, Fredrik Larsson, Tobias Torndahl, Erik M J Johansson, Gerrit Boschloo, Marika Edoff
The compatibility of atomic layer deposition directly onto FAPBI3:MAPbBr3 perovskite films is investigated by exposing the perovskite films to the full or partial atomic layer deposition processes for the electron selective layer candidates ZnO and SnOx. Exposing the samples to the heat, the vacuum and even the counter reactant of H2O of the atomic layer deposition processes does not appear to alter the perovskite films in terms of crystallinity, but the choice of metal precursor is found to be critical. The Zn precursor Zn(C2H5)2 either by itself or in combination with H2O during the ZnO ALD process is found to enhance the decomposition of the bulk of the perovskite film into PbI2 without even forming ZnO...
August 9, 2017: ACS Applied Materials & Interfaces
Chanchal Mondal, Siddharth G Chatterjee
The surface of a turbulent liquid is visualized as consisting of a large number of chaotic eddies or liquid elements. Assuming that surface elements of a particular age have renewal frequencies that are integral multiples of a fundamental frequency quantum, and further assuming that the renewal frequency distribution is of the Boltzmann type, performing a population balance for these elements leads to the Danckwerts surface age distribution. The basic quantum is what has been traditionally called the rate of surface renewal...
July 2017: Royal Society Open Science
Apoorv Shanker, Chen Li, Gun-Ho Kim, David Gidley, Kevin P Pipe, Jinsang Kim
High thermal conductivity is critical for many applications of polymers (for example, packaging of light-emitting diodes), in which heat must be dissipated efficiently to maintain the functionality and reliability of a system. Whereas uniaxially extended chain morphology has been shown to significantly enhance thermal conductivity in individual polymer chains and fibers, bulk polymers with coiled and entangled chains have low thermal conductivities (0.1 to 0.4 W m(-1) K(-1)). We demonstrate that systematic ionization of a weak anionic polyelectrolyte, polyacrylic acid (PAA), resulting in extended and stiffened polymer chains with superior packing, can significantly enhance its thermal conductivity...
July 2017: Science Advances
Vishal M Toprani, John M Hickey, Neha Sahni, Ronald T Toth, George A Robertson, C Russell Middaugh, Sangeeta B Joshi, David B Volkin
A novel protein adjuvant double mutant E.coli heat labile toxin, LT(R192G/L211A) or dmLT, is in preclinical and early clinical development with various vaccine candidates. Structural characterization and formulation development of dmLT will play a key role in its successful process development, scale-up/transfer and commercial manufacturing. This work describes extensive analytical characterization of structural integrity and physicochemical stability profile of dmLT from a lyophilized clinical formulation...
August 2, 2017: Journal of Pharmaceutical Sciences
Alok Ghanekar, Yanpei Tian, Sinong Zhang, Yali Cui, Yi Zheng
In this work, we theoretically analyze the performance characteristics of a near-field thermophotovoltaic system consisting a Mie-metamaterial emitter and GaSb-based photovoltaic cell at separations less than the thermal wavelength. The emitter consists of a tungsten nanoparticle-embedded thin film of SiO 2 deposited on bulk tungsten. Numerical results presented here are obtained using formulae derived from dyadic Green's function formalism and Maxwell-Garnett-Mie theory. We show that via the inclusion of tungsten nanoparticles, the thin layer of SiO 2 acts like an effective medium that enhances selective radiative heat transfer for the photons above the band gap of GaSb...
July 31, 2017: Materials
Junji Fujita, Junko Umeda, Katsuyoshi Kondoh
The elemental mixture of Mg-6 wt %Al-1 wt %Zn-0.3 wt %Mn (AZ61B) alloy powder and CaO particles was consolidated by an equal-channel angular bulk mechanical alloying (ECABMA) process to form a composite precursor. Subsequently, the precursor was subjected to a heat treatment to synthesize fine Al₂Ca particles via a solid-state reaction between the Mg-Al matrix and CaO additives. Scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS) and electron probe micro-analysis on the precursor indicated that 4...
June 28, 2017: Materials
Bin Liu, Jizhu Hu, Jun Zhou, Ronggui Yang
Thermoelectric materials which can convert energies directly between heat and electricity are used for solid state cooling and power generation. There is a big challenge to improve the efficiency of energy conversion which can be characterized by the figure of merit (ZT). In the past two decades, the introduction of nanostructures into bulk materials was believed to possibly enhance ZT. Nanocomposites is one kind of nanostructured material system which includes nanoconstituents in a matrix material or is a mixture of different nanoconstituents...
April 15, 2017: Materials
Almudena Díaz-García, Carmen Martínez-García, Teresa Cotes-Palomino
Action on climate, the environment, and the efficient use of raw materials and resources are important challenges facing our society. Against this backdrop, the construction industry must adapt to new trends and environmentally sustainable construction systems, thus requiring lines of research aimed at keeping energy consumption in new buildings as low as possible. One of the main goals of this research is to efficiently contribute to reducing the amount of residue from olive oil extraction using a two-phase method...
January 25, 2017: Materials
Shaomao Xu, Yanan Chen, Yiju Li, Aijiang Lu, Yonggang Yao, Jiaqi Dai, Yanbin Wang, Boyang Liu, Steven D Lacey, Glenn R Pastel, Yudi Kuang, Valencia A Danner, Feng Jiang, Kun Kelvin Fu, Liangbing Hu
The synthesis of nanoscale metal compound catalysts has attracted much research attention in the past decade. The challenges of preparation of the metal compound include the complexity of the synthesis process and difficulty of precise control of the reaction conditions. Herein, we report an in situ synthesis of nanoparticles via a high-temperature pulse method where the bulk material acts as the precursor. During the process of rapid heating and cooling, swift melting, anchoring, and recrystallization occur, resulting in the generation of high-purity nanoparticles...
August 8, 2017: Nano Letters
Pierre Roumanille, Valérie Baco-Carles, Corine Bonningue, Michel Gougeon, Benjamin Duployer, Philippe Monfraix, Hoa Le Trong, Philippe Tailhades
Two bismuth oxalates, namely, Bi2(C2O4)3·7H2O and Bi(C2O4)OH, were studied in terms of synthesis, structural characterization, particle morphology, and thermal behavior under several atmospheres. The oxalate powders were produced by chemical precipitation from bismuth nitrate and oxalic acid solutions under controlled pH, then characterized by X-ray diffraction (XRD), temperature-dependent XRD, IR spectroscopy, scanning electron microscopy, and thermogravimetric differential thermal analyses. New results on the thermal decomposition of bismuth oxalates under inert or reducing atmospheres are provided...
August 3, 2017: Inorganic Chemistry
Minryeong Cha, Juyeon Yi, Yong Woon Kim
We consider a system consisting of a charged cylinder in the presence of neutralizing counterions. This system is well known to exhibit the Manning transition of counterion condensation onto the charged cylinder. We study the criticality and the scaling properties of the Manning transition, analyzing involved thermodynamic quantities such as condensed fraction, its fluctuation, and heat capacity. Through the Monte Carlo simulations and finite-size scaling analysis, we find that near the transition point the examined quantities exhibit scale-invariant behaviors with specific exponents, which provides an evidence that the Manning transition is a critical phenomenon having a scale-invariant property, analogous to bulk phase transitions...
August 2017: European Physical Journal. E, Soft Matter
Lin Zhang, Ling Liu
Ultralow thermal conductivities of bulk polymers greatly limit their applications in areas demanding fast heat dissipation, such as flexible electronics and microelectronics. Therefore, polymeric composites incorporating highly thermally conductive filler materials (e.g. graphene and carbon nanotubes) have been produced to address the issue. However, despite some enhancement, thermal conductivities of these materials are still far below theoretical predictions, mainly due to the inefficient thermal transport across material interfaces...
August 2, 2017: ACS Applied Materials & Interfaces
Qianru Wang, Naga Neehar Dingari, Cullen R Buie
Insulator-based dielectrophoresis (iDEP) has emerged as a powerful tool for multiple biomicrofluidic operations, such as cell separation and concentration. The key feature for iDEP systems is the alteration of insulating microchannel geometries to create strong electric field gradients. Under AC electric fields, this strong electric field gradient can affect fluid flow by (at least) two nonlinear electrokinetic phenomena; a) electrothermal flow due to Joule heating and b) induced charge electroosmosis (ICEO) near the microchannel constrictions of small (but finite) permittivity and conductivity...
August 1, 2017: Electrophoresis
Satoshi Watanabe, Takahisa Ohta, Ryota Urata, Tetsuya Sato, Kazuto Takaishi, Masanobu Uchiyama, Tetsuya Aoyama, Masashi Kunitake
The temperature and concentration dependencies of the crystallization of two small-molecular semiconductors were clarified by constructing quasi-phase diagrams at air/oil interfaces and in bulk oil phases. A quinoidal oligothiophene derivative with four alkyl chains (QQT(CN)4) in 1,1,2,2-tetrachroloethane (TCE) and a thienoacene derivative with two alkyl chains (C8-BTBT) in o-dichlorobenzene were used. The apparent crystal nucleation temperature (Tn) and dissolution temperature (Td) of the molecules were determined based on optical microscopy examination in closed glass capillaries and open dishes during slow cooling and heating processes, respectively...
July 31, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Mariya A Pindrus, James L Cole, Japneet Kaur, Steven J Shire, Sandeep Yadav, Devendra S Kalonia
PURPOSE: To systematically analyze shape and size of soluble irreversible aggregates and the effect of aggregate formation on viscosity. METHODS: Online light scattering, refractive index and viscosity detectors attached to HPLC (Viscotek®) were used to study aggregation, molecular weight and intrinsic viscosity of bovine serum albumin (BSA). Irreversible aggregates were generated by heat stress. Bulk viscosity was measured by an oscillating piston viscometer. RESULTS: As BSA was heated at a higher concentration or for a longer time, the relative contribution, molecular weight and intrinsic viscosity of aggregate species increased...
July 27, 2017: Pharmaceutical Research
C M Pépin, G Geneste, A Dewaele, M Mezouar, P Loubeyre
High pressure promotes the formation of polyhydrides with unusually high hydrogen-to-metal ratios. These polyhydrides have complex hydrogenic sublattices. We synthesized iron pentahydride (FeH5) by a direct reaction between iron and H2 above 130 gigapascals in a laser-heated diamond anvil cell. FeH5 exhibits a structure built of atomic hydrogen only. It consists of intercalated layers of quasicubic FeH3 units and four-plane slabs of thin atomic hydrogen. The distribution of the valence electron density indicates a bonding between hydrogen and iron atoms but none between hydrogen atoms, presenting a two-dimensional metallic character...
July 28, 2017: Science
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