16,393 research outputs found
Supergiant Barocaloric Effects in Acetoxy Silicone Rubber over a Wide Temperature Range: Great Potential for Solid-state Cooling
Solid-state cooling based on caloric effects is considered a viable
alternative to replace the conventional vapor-compression refrigeration
systems. Regarding barocaloric materials, recent results show that elastomers
are promising candidates for cooling applications around room-temperature. In
the present paper, we report supergiant barocaloric effects observed in acetoxy
silicone rubber - a very popular, low-cost and environmentally friendly
elastomer. Huge values of adiabatic temperature change and reversible
isothermal entropy change were obtained upon moderate applied pressures and
relatively low strains. These huge barocaloric changes are associated both to
the polymer chains rearrangements induced by confined compression and to the
first-order structural transition. The results are comparable to the best
barocaloric materials reported so far, opening encouraging prospects for the
application of elastomers in near future solid-state cooling devices.Comment: 19 pages, 7 figures, 2 table
A framework for certification of large-scale component-based parallel computing systems in a cloud computing platform for HPC services
This paper addresses the verification of software components in the context of their orchestration to build
cloud-based scientific applications with high performance computing requirements. In such a scenario, components
are often supplied by different sources and their cooperation rely on assumptions of conformity with
their published behavioral interfaces. Therefore, a faulty or ill-designed component, failing to obey to the
envisaged behavioral requirements, may have dramatic consequences in practice. Certifier components, introduced
in this paper, implement a verification as a service framework and are able to access the implementation
of other components and verify their consistency with respect to a number of functional, safety and liveness
requirements relevant to a specific application or a class of them. It is shown how certifier components can be
smoothly integrated in HPC Shelf, a cloud-based platform for high performance computing in which different
sorts of users can design, deploy and execute scientific applications.SmartEGOV:
Harnessing EGOV for Smart Governance (Foundations, methods, Tools) / NORTE-01-0145-FEDER000037, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the
European Regional Development Fund (EFD
Magnetic phases evolution in the LaMn1-xFexO3+y system
We have investigated the crystal structure and magnetic properties for
polycrystalline samples of LaMn1-xFexO3+y, in the whole range x=0.0 to x=1.0,
prepared by solid state reaction in air. All samples show the ORT-2
orthorhombic structure that suppresses the Jahn-Teller distortion, thus
favoring a ferromagnetic (FM) superexchange (SE) interaction between
Mn^{3+}-O-Mn^{3+}. For x=0.0 the oxygen excess (y ~ 0.09) produces vacancies in
the La and Mn sites and generates a fraction around 18% of Mn^{4+} ions and 82%
of the usual Mn^{3+} ions, with possible double exchange interaction between
them. The Fe doping in this system is known to produce only stable Fe^{3+}
ions. We find an evolution from a fairly strong FM phase with a Curie
temperature T_{C} ~ 160 K, for x=0.0, to an antiferromagnetic (AFM) phase with
T_{N} = 790 K, for x=1.0, accompanied by clear signatures of a cluster-glass
behavior. For intermediate Fe contents a mixed-phase state occurs, with a
gradual decrease (increase) of the FM (AFM) phase, accompanied by a systematic
transition broadening for 0.2 < x < 0.7. A model based on the expected exchange
interaction among the various magnetic-ion types, accounts very well for the
saturation-magnetization dependence on Fe doping.Comment: 27 pages, 9 figure
Interação do parasitoide Melittobia australica Girault (Hymenoptera: Eulophidae) com a vespa solitária Sceliphron asiaticum Linneaus (Hymenoptera: Sphecidae) no Brasil.
Autoria: QUERINO [i.e. SILVA], R. B. Q. da. RANYSE BARBOSA QUERINO DA SILV
Separação rápida de padrão de b-caroteno a partir de mandioca Jarí utilizando cromatografia líquida de alta eficiência (CLAE) em escala analítica.
Electric field inversion asymmetry: Rashba and Stark effects for holes in resonant tunneling devices
We report experimental evidence of excitonic spin-splitting, in addition to
the conventional Zeeman effect, produced by a combination of the Rashba
spin-orbit interaction, Stark shift and charge screening. The
electric-field-induced modulation of the spin-splitting are studied during the
charging and discharging processes of p-type GaAs/AlAs double barrier resonant
tunneling diodes (RTD) under applied bias and magnetic field. The abrupt
changes in the photoluminescence, with the applied bias, provide information of
the charge accumulation effects on the device.Comment: 4 pages, 2 figure
Mudanças na estrutura da população de espécies arbóreas da família Humiriaceae em consequência de exploração florestal de impacto reduzido na Amazônia brasileira.
Effect of different enrichment media and DNA extraction techniques on Salmonella detection by PCR in SWINE feces
The aim of this study was to evaluate different selective enrichment broths and DNA extraction techniques on the detection of Salmonella Typhimurium in swine feces by PCR. Feces samples (n=10) were inoculated with approximately 102 Salmonella Typhimurium organisms, first enriched in GN-Hajna broth and secondly enriched in Rappaport-Vassiliadis, Muller-Kaufmann tetrathionate and selenite-cystine broths. In order to produce DNA-templates for PCR, aliquots from the broths were subjected to three DNA extraction methods: boiling-centrifugation, salting-out and phenol-chloroform. Detection of Salmonella was significant lower when phenol-chloroform was applied to selenite-cystine and Muller-Kaufmann tetrathionate (P\u3c0.05). The boiling-centrifugation technique had best cost/benefit ratio and can be successfully used as a rapid DNA template preparation from the three enriched broths tested
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