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Bulk heating

Anabel Palacios, Alvaro De Gracia, Laia Haurie, Luisa F Cabeza, A Inés Fernández, Camila Barreneche
The implementation of organic phase change materials (PCMs) in several applications such as heating and cooling or building comfort is an important target in thermal energy storage (TES). However, one of the major drawbacks of organic PCMs implementation is flammability. The addition of flame retardants to PCMs or shape-stabilized PCMs is one of the approaches to address this problem and improve their final deployment in the building material sector. In this study, the most common organic PCM, Paraffin RT-21, and fatty acids mixtures of capric acid (CA), myristic acid (MA), and palmitic acid (PA) in bulk, were tested to improve their fire reaction...
January 12, 2018: Materials
Mauricelio Bezerra da Silva, Regina C R Santos, Paulo T C Freire, Ewerton W S Caetano, Valder N Freire
Boric acid (H3BO3) is being used effectively nowadays in traps/baits for the management of Aedes aegypti L. and Aedes albopictus Skuse species of mosquitoes, which are the main spreading vectors worldwide for diseases like malaria, dengue and zika. Previously, we have published results on the structural, electronic and optical properties of its molecular triclinic H3BO3-2A and trigonal H3BO3-3T polymorphs within the framework of density functional theory (DFT). Due to the renewed importance of these materials, the focus of this work is on the vibrational properties of the bulk boric acid 2A and 3T polymorphs...
January 12, 2018: Journal of Physical Chemistry. A
K Kamiya, T Takeuchi, N Kabeya, N Wada, T Ishimasa, A Ochiai, K Deguchi, K Imura, N K Sato
Superconductivity is ubiquitous as evidenced by the observation in many crystals including carrier-doped oxides and diamond. Amorphous solids are no exception. However, it remains to be discovered in quasicrystals, in which atoms are ordered over long distances but not in a periodically repeating arrangement. Here we report electrical resistivity, magnetization, and specific-heat measurements of Al-Zn-Mg quasicrystal, presenting convincing evidence for the emergence of bulk superconductivity at a very low transition temperature of [Formula: see text] K...
January 11, 2018: Nature Communications
Maximilian Lasserus, Martin Schnedlitz, Daniel Knez, Roman Messner, Alexander Schiffmann, Florian Lackner, Andreas W Hauser, Ferdinand Hofer, Wolfgang E Ernst
Alloying processes in nanometre-sized Ag@Au and Au@Ag core@shell particles with average radii of 2 nm are studied via high resolution Transmission Electron Microscopy (TEM) imaging on in situ heatable carbon substrates. The bimetallic clusters are synthesized in small droplets of superfluid helium under fully inert conditions. After deposition, they are monitored during a heating cycle to 600 K and subsequent cooling. The core-shell structure, a sharply defined feature of the TEM High-Angle Annular Dark-Field images taken at room temperature, begins to blur with increasing temperature and transforms into a fully mixed alloy around 573 K...
January 10, 2018: Nanoscale
Li Shi, Liuqing Yang, Wei Zhou, Yanyu Liu, Lisha Yin, Xiao Hai, Hui Song, Jinhua Ye
Holey defective g-C3 N4 photocatalysts, which are easily prepared via a novel photoassisted heating process, are reported. The photoassisted treatment not only helps to create abundant holes, endowing g-C3 N4 with more exposed catalytic active sites and crossplane diffusion channels to shorten the diffusion distance of both reactants from the surface to bulk and charge carriers from the bulk to surface, but also introduces nitrogen vacancies in the tri-s-triazine repeating units of g-C3 N4 , inducing the narrowing of intrinsic bandgap and the formation of defect states within bandgap to extend the visible-light absorption range and suppress the radiative electron-hole recombination...
January 10, 2018: Small
Xiaojuan Tian, Yun Li, Zhuo Chen, Qi Li, Liqiang Hou, Jiaye Wu, Yushu Tang, Yongfeng Li
Boron nitride nanosheets (BNNS) hold the similar two-dimensional structure as graphene and unique properties complementary to graphene, which makes it attractive in application ranging from electronics to energy storage. The exfoliation of boron nitride (BN) still remains challenge and hinders the applications of BNNS. In this work, the preparation of BNNS has been realized by a shear-assisted supercritical CO2 exfoliation process, during which supercritical CO2 intercalates and diffuses between boron nitride layers, and then the exfoliation of BN layers is obtained in the rapid depressurization process by overcoming the van der Waals forces...
December 19, 2017: Scientific Reports
Stephanie Loeb, Chuanhao Li, Jae-Hong Kim
A simple heat treatment, perhaps the most globally recognized point-of-use water sterilization method, is seemingly effective against all major pathogens of concern, but bulk water boiling is not energy efficient or sustainable. Herein, we present the first application of solar-to-thermal converting nanomaterials for the direct inactivation of bacteria and viruses in drinking water through the application of Au nanorods, carbon black, and Au nanorod-carbon black composite materials as light absorbers. With broad absorption bands spanning the visible and near-infrared wavelengths, at sufficient concentrations, these nanoparticles induce multiple scattering events, increasing photon absorption probability and concentrating the light within a small spatial domain, leading to localized, intense heating that inactivates microorganisms in close proximity...
December 14, 2017: Environmental Science & Technology
Monica Vasiliu, J Grant Hill, Kirk A Peterson, David A Dixon
Geometry parameters, vibrational frequencies, heats of formation, bond dissociation energies, cohesive energies, and selected fluoride affinities (difluorides) are predicted for the late alkaline earth (Sr, Ba and Ra) oxides, fluorides, chlorides, and hydroxides at the coupled cluster theory [CCSD(T)] level. Additional corrections (scalar relativistic and pseudopotential corrections, vibrational zero-point energies, and atomic spin-orbit effects) were included to accurately calculate the total atomization energies and heats of formation following the Feller-Peterson-Dixon methodology...
December 14, 2017: Journal of Physical Chemistry. A
Stepan Hlushak
Temperature, pressure and pore-size dependences of the heat of adsorption, adsorption stress, and adsorption capacity of methane in simple models of slit and cylindrical carbon pores are studied using classical density functional theory (CDFT) and grand-canonical Monte-Carlo (MC) simulation. Studied properties depend nontrivially on the bulk pressure and the size of the pores. Heat of adsorption increases with loading, but only for sufficiently narrow pores. While the increase is advantageous for gas storage applications, it is less significant for cylindrical pores than for slits...
December 14, 2017: Physical Chemistry Chemical Physics: PCCP
Ruijing Ge, Xiaohan Wu, Myungsoo Kim, Jianping Shi, Sushant Sudam Sonde, Li Tao, Yanfeng Zhang, Jack Lee, Deji Akinwande
Recently, two-dimensional (2D) atomic sheets have inspired new ideas in nanoscience including topologically-protected charge transport, spatially-separated excitons, and strongly anisotropic heat transport. Here, we report the intriguing observation of stable non-volatile resistance switching (NVRS) in single-layer atomic sheets sandwiched between metal electrodes. NVRS is observed in the prototypical semiconducting (MX2, M=Mo, W; and X=S, Se) transitional metal dichalcogenides (TMDs), which alludes to the universality of this phenomenon in TMD monolayers, and offers forming-free switching...
December 13, 2017: Nano Letters
Hongbo Qin, Xinghe Luan, Chuang Feng, Daoguo Yang, Guoqi Zhang
For the limitation of experimental methods in crystal characterization, in this study, the mechanical, thermodynamic and electronic properties of wurtzite and zinc-blende GaN crystals were investigated by first-principles calculations based on density functional theory. Firstly, bulk moduli, shear moduli, elastic moduli and Poisson's ratios of the two GaN polycrystals were calculated using Voigt and Hill approximations, and the results show wurtzite GaN has larger shear and elastic moduli and exhibits more obvious brittleness...
December 12, 2017: Materials
Peng Xu, T J Huffman, In Hae Kwak, Amlan Biswas, M M Qazilbash
We investigate the temperature dependence of infrared properties at nanometer length scales in La0.67Sr0.33MnO3 (LSMO) thin film with a thickness of 47 unit cells grown on SrTiO3 substrate. The infrared nano-imaging experiments were performed using a near-field optical microscope in conjunction with a variable temperature heating stage. The near-field infrared data is consistent with the bulk of the LSMO film undergoing the thermally-driven non-percolative second-order transition from a metallic, ferromagnetic phase to an insulating, paramagnetic phase...
December 11, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Dorri Halbertal, Moshe Ben Shalom, Aviram Uri, Kousik Bagani, Alexander Y Meltzer, Ido Marcus, Yuri Myasoedov, John Birkbeck, Leonid S Levitov, Andre K Geim, Eli Zeldov
Conversion of electric current into heat involves microscopic processes that operate on nanometer length scales and release minute amounts of power. Although central to our understanding of the electrical properties of materials, individual mediators of energy dissipation have so far eluded direct observation. Using scanning nanothermometry with submicrokelvin sensitivity, we visualized and controlled phonon emission from individual atomic-scale defects in graphene. The inferred electron-phonon "cooling power spectrum" exhibits sharp peaks when the Fermi level comes into resonance with electronic quasi-bound states at such defects...
December 8, 2017: Science
Sungwoo Sohn, Yujun Xie, Yeonwoong Jung, Jan Schroers, Judy J Cha
Many physical phenomena deviate from their established frameworks when the system approaches relevant length scales governing the phenomena. In crystallization, the relevant length scales are the nucleation length set by the nucleus size and density, and the growth length set by diffusion fields. Here we observe unexpected crystallization phenomena at the nanoscale, using metallic glass (MG) nanorods and in situ transmission electron microscopy. The asymmetry between critical heating and cooling rates disappears for small MG nanorods...
December 7, 2017: Nature Communications
Zhuang Ma, Xing Li, Ling Liu, Yanbo Liu
NiCr₂O₄ as a potential protection for thermal barrier coatings (TBCs) against the attack of molten calcium-magnesium-alumino-silicate (CMAS) was studied by a CMAS-contacting experiment. Atmospheric plasma sprayed coatings and sintered bulk materials were fabricated, covered with CMAS deposits, and exposed to 1200 °C for 24 h. Nano-sized CMAS-NiCr₂O₄ mixed powder was manufactured by ball milling and then conducted heat treatment under the same condition. The results show that no reacting product was found at the border between molten CMAS and NiCr₂O₄ and no element transportation occurred...
December 6, 2017: Materials
Zongqing Ren, Jaeho Lee
Artificial nanostructures have improved prospects of thermoelectric systems by enabling selective scattering of phonons and demonstrating significant thermal conductivity reductions. While the low thermal conductivity provides necessary temperature gradients for thermoelectric conversion, the heat generation is detrimental to electronic systems where high thermal conductivity are preferred. The contrasting needs of thermal conductivity are evident in thermoelectric cooling systems, which call for a fundamental breakthrough...
December 4, 2017: Nanotechnology
Zhiyong Han, Yong Liu, Min Zhong, Guozhong Shi, Qibin Li, Dan Zeng, Yu Zhang, Yongqiang Fei, Yanhua Xie
Waste management in rural areas has become a major challenge for governments of developing countries. The success of waste management decisions directly lies in the accuracy and reliability of the data on which choices are based; many factors influence these data. Here, we examined the factors influencing domestic waste in rural areas of developing countries (RADIC), using both field surveys and by reviewing previous literature. The social factors included population, education and culture. There was a positive linear relationship between waste generation amount and population size (R2 = 0...
November 29, 2017: Waste Management
Christina Maria Tonauer, Markus Seidl, Thomas Loerting
The pressure dependence of the crystallization temperature of different forms of expanded high density amorphous ice (eHDA) was scrutinized. Crystallization at pressures 0.05-0.30 GPa was followed using volumetry and powder X-ray diffraction. eHDA samples were prepared via isothermal decompression of very high-density amorphous ice (VHDA) at 140 K to different end pressures between 0.07-0.30 GPa (eHDA<sup>0.07-0.3</sup>). At 0.05-0.17 GPa the crystallization line T<sub>x</sub> (p) of all eHDA variants is the same...
November 30, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Xing Huang, Shuai Zhang, Liyao Liu, Lei Yu, Genfu Chen, Wei Xu, Daoben Zhu
Highly crystalline material of Copper (II) benzenehexathiolate coordination polymer (Cu-BHT) has been prepared. Its two dimensional kagomè structure has been confirmed by powder x-ray diffraction (PXRD), high-resolution transmission electron microscope (HRTEM) and high-resolution scanning transmission electron microscope (STEM). The as-prepared sample exhibits bulk superconductivity at ~ 0.25 K which is confirmed by the zero resistivity, AC magnetic susceptibility and specific heat measurements. Another diamagnetic transition at ~ 3K suggests that there is a second superconducting phase which may be associated to the single layer or few-layer of Cu-BHT...
November 21, 2017: Angewandte Chemie
C Riekel, M Burghammer, I Snigirev, M Rosenthal
We determined stress-induced deformations and the thermal stability of nanorod-shaped tobacco mosaic virus (TMV) capsids in coffee-ring structures by X-ray nanodiffraction. The hexagonal capsids lattice transforms under compression in the outer boundary zone of the coffee-ring into a tetragonal lattice. The helical pitch of the nanorods increases by about 2.5% across the outer boundary zone while the lateral distance between nanorods decreases continuously across the whole coffee-ring structure by about 2% due to compressive forces...
November 15, 2017: Soft Matter
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