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Heat wave

Allan Garcia, Xavier Buelna, Evgeny Popov, Jussi Eloranta
Intense shock waves in superfluid (4)He between 1.7 and 2.1 K are generated by rapidly expanding confined plasma from laser ablation of a metal target immersed in the liquid. The resulting shock fronts in the liquid with initial velocities up to ca. Mach 10 are visualized by time-resolved shadowgraph photography. These high intensity shocks decay within 500 ns into less energetic shock waves traveling at Mach 2, which have their lifetime in the microsecond time scale. Based on the analysis using the classical Rankine-Hugoniot theory, the shock fronts created remain in the solid phase up to 1 μs and the associated thermodynamic state appears outside the previously studied region...
September 28, 2016: Journal of Chemical Physics
Donato Belmonte, Carlo Gatti, Giulio Armando Ottonello, Pascal Richet, Marino Vetuschi Zuccolini
Thermodynamic and thermophysical properties of Na2SiO3 in the Cmc21 structural state are computed ab-initio using the hybrid B3LYP density functional method. The static properties at the athermal limit are first evaluated through a symmetry-preserving relaxation procedure. The thermodynamic properties that depend on vibrational frequencies viz, heat capacities, thermal expansion, thermal derivative of the bulk modulus, thermal correction to internal energy, enthalpy, Gibbs free energy, are then computed in the framework of quasi-harmonic approximation...
October 19, 2016: Journal of Physical Chemistry. A
Guillaume Van der Rest, Human Rezaei, Frédéric Halgand
Prion protein is involved in deadly neurodegenerative diseases. Its pathogenicity is linked to its structural conversion (α-helix to β-strand transition). However, recent studies suggest that prion protein can follow a plurality of conversion pathways, which hints towards different conformers that might coexist in solution. To gain insights on the plasticity of the ovine prion protein (PrP) monomer, wild type (A136, R154, Q171), mutants and deletions of ARQ were studied by traveling wave ion mobility experiments coupled to mass spectrometry...
October 18, 2016: Journal of the American Society for Mass Spectrometry
D L Hoover, A K Knapp, M D Smith
Extreme heat waves and drought are predicted to increase in frequency and magnitude with climate change. These extreme events often co-occur, making it difficult to separate their direct and indirect effects on important ecophysiological and carbon cycling processes such as photosynthesis. Here, we assessed the independent and interactive effects of experimental heat waves and drought on photosynthesis in Andropogon gerardii, a dominant C4 grass in a native mesic grassland. We experimentally imposed a two-week heat wave at four intensity levels under two contrasting soil moisture regimes: a well-watered control and an extreme drought...
October 18, 2016: Oecologia
Yuki Osaka, Satoshi Sugano, Shuichi Hashimoto
Fabricating nano-sized through-holes on a coverslip approximately 100 μm thick is challenging but rewarding when applied to ultrafine filters that separate proteins and DNA of various sizes and isolate viruses from cells. Toward this end, we developed an in situ etching-assisted laser processing technique exploiting gold nanoparticles. Plasmonic heating of a single gold nanoparticle through focused illumination of a continuous-wave laser beam enables structural modifications to be localized to the contact area on the glass surface...
October 18, 2016: Nanoscale
Fuminao Kishimoto, Masayuki Matsuhisa, Shinichiro Kawamura, Satoshi Fujii, Shuntaro Tsubaki, Masato M Maitani, Eiichi Suzuki, Yuji Wada
Various microwave effects on chemical reactions have been observed, reported and compared to those carried out under conventional heating. These effects are classified into thermal effects, which arise from the temperature rise caused by microwaves, and non-thermal effects, which are attributed to interactions between substances and the oscillating electromagnetic fields of microwaves. However, there have been no direct or intrinsic demonstrations of the non-thermal effects based on physical insights. Here we demonstrate the microwave enhancement of oxidation current of water to generate dioxygen with using an α-Fe2O3 electrode induced by pulsed microwave irradiation under constantly applied potential...
October 14, 2016: Scientific Reports
Dominik Florian Stangler, Andreas Hamann, Hans-Peter Kahle, Heinrich Spiecker
A useful approach to monitor tree response to climate change and environmental extremes is the recording of long-term time series of stem radial variations obtained with precision dendrometers. Here, we study the impact of environmental stress on seasonal growth dynamics and productivity of yellow birch (Betula alleghaniensis Britton) and sugar maple (Acer saccharum Marsh.) in the Great Lakes, St Lawrence forest region of Ontario. Specifically, we research the effects of a spring heat wave in 2010, and a summer drought in 2012 that occurred during the 2005-14 study period...
October 13, 2016: Tree Physiology
Celia Olabarria, Ignacio Gestoso, Fernando P Lima, Elsa Vázquez, Luc A Comeau, Filipa Gomes, Rui Seabra, José M F Babarro
Different combinations of behavioural and physiological responses may play a crucial role in the ecological success of species, notably in the context of biological invasions. The invasive mussel Xenostrobus securis has successfully colonised the inner part of the Galician Rias Baixas (NW Spain), where it co-occurs with the commercially-important mussel Mytilus galloprovincialis. This study investigated the effect of a heatwave on the physiological and behavioural responses in monospecific or mixed aggregations of these species...
2016: PloS One
Shiteng Zhao, Bimal Kad, Bruce A Remington, Jerry C LaSalvia, Christopher E Wehrenberg, Kristopher D Behler, Marc A Meyers
Solid-state shock-wave propagation is strongly nonequilibrium in nature and hence rate dependent. Using high-power pulsed-laser-driven shock compression, unprecedented high strain rates can be achieved; here we report the directional amorphization in boron carbide polycrystals. At a shock pressure of 45∼50 GPa, multiple planar faults, slightly deviated from maximum shear direction, occur a few hundred nanometers below the shock surface. High-resolution transmission electron microscopy reveals that these planar faults are precursors of directional amorphization...
October 12, 2016: Proceedings of the National Academy of Sciences of the United States of America
Li An, Zhonghong Xia, Peikai Chen, Dingguo Xia
Transition metal oxynitrides have now garnered growing interest in our quest for highly efficient alternatives to Pt in direct methanol alkaline fuel cells. Herein, carbon supported Co3Mo2OxN6-x was synthesized via a simple two-step approach wherein the reactants undergo refluxing and heat treatment in NH3. For the as-prepared Co3Mo2OxN6-x catalyst, uniformly dispersed on the XC-72, with the particles size averaged at 5 nm, the catalytic activities towards oxygen reduction reaction in alkaline media are related to the commercial Pt/C, such as the comparable onset potential (0...
October 12, 2016: ACS Applied Materials & Interfaces
Jonathan B Armstrong, Eric J Ward, Daniel E Schindler, Peter J Lisi
As climate change increases maximal water temperatures, behavioural thermoregulation may be crucial for the persistence of coldwater fishes, such as salmonids. Although myriad studies have documented behavioural thermoregulation in southern populations of salmonids, few if any have explored this phenomenon in northern populations, which are less likely to have an evolutionary history of heat stress, yet are predicted to experience substantial warming. Here, we treated a rare heat wave as a natural experiment to test whether wild sockeye salmon (Oncorhynchus nerka) at the northern extent of their primary range (60° latitude) can thermoregulate in response to abnormally high thermal conditions...
2016: Conservation Physiology
Connie L Thomas
No abstract text is available yet for this article.
2016: Psychiatry
Zhenzhu Xu, Yanhui Hou, Lihua Zhang, Tao Liu, Guangsheng Zhou
Global warming is projected to continue, leading to intense fluctuations in precipitation and heat waves and thereby affecting the productivity and the relevant biological processes of grassland ecosystems. Here, we determined the functional responses to warming and altered precipitation in both typical and desert steppes. The results showed that watering markedly increased the aboveground net primary productivity (ANPP) in a typical steppe during a drier year and in a desert steppe over two years, whereas warming manipulation had no significant effect...
October 10, 2016: Scientific Reports
V M Malkin, N J Fisch
Powerful incoherent laser pulses can propagate in focusing Kerr media much longer distances than can coherent pulses, due to the fast phase mixing that prevents transverse filamentation. This distance is limited by 4-wave scattering, which accumulates waves at small transverse wave numbers, where phase mixing is too slow to retain the incoherence and thus prevent the filamentation. However, we identify how this theoretical limit can be overcome by countering this accumulation through transverse heating of the pulse by random fluctuations of the refractive index...
September 23, 2016: Physical Review Letters
S-O Park, W K Kim
Heat stress in hot seasons is a major problem in poultry production, particularly in humid areas. The aim of this study was to determine the pharmacodynamics of betaine on the blood and cecal short chain fatty acid profile in meat-type ducks exposed to heat stress. Three-hundred-sixty meat-type ducks (Anas platyrhynchos domesticus) were randomly allocated into 4 treatments: C (heat stress control without betaine), T1 (700 ppm betaine), T2 (1,000 ppm betaine), and T3 (1,300 ppm betaine). Each treatment had 6 replicated pens with 15 meat-type ducks per pen...
October 4, 2016: Poultry Science
Casey A Marjerrison, Corey M Thompson, Gabrielle Sala, Dalini D Maharaj, Edwin Kermarrec, Yipeng Cai, Alannah M Hallas, Murray N Wilson, Timothy J S Munsie, Garrett E Granroth, Roxana Flacau, John E Greedan, Bruce D Gaulin, Graeme M Luke
Double perovskites (DP) of the general formula Ba2MReO6, where M = Mg, Zn, and Y2/3, all based on Re(6+) (5d(1), t2g(1)), were synthesized and studied using magnetization, heat capacity, muon spin relaxation, and neutron-scattering techniques. All are cubic, Fm3̅m, at ambient temperature to within the resolution of the X-ray and neutron diffraction data, although the muon data suggest the possibility of a local distortion for M = Mg. The M = Mg DP is a ferromagnet, Tc = 18 K, with a saturation moment ∼0...
October 4, 2016: Inorganic Chemistry
Maria Pia Gatto, Renato Cabella, Monica Gherardi
OBJECTIVE: This study investigates the possible influence of global climate change (GCC) on exposure to plant protection products (PPP) in the workplace. METHODS: The paper has evaluated the main potential relationships between GCC and occupational exposure to pesticides, by highlighting how global warming might affect their future use and by reviewing its possible consequence on workers' exposure. RESULTS: Global warming, influencing the spatial and temporal distribution and proliferation of weeds, the impact of already present insect pests and pathogens and the introduction of new infesting species, could cause a changed use of pesticides in terms of higher amounts, doses and types of products applied, so influencing the human exposure to them during agricultural activities...
July 2016: Annali Dell'Istituto Superiore di Sanità
Triin Kaldur, Eve Unt, Vahur Ööpik, Mihkel Zilmer, Jaan Eha, Kaido Paapstel, Jaak Kals
BACKGROUND AND OBJECTIVE: The aim of the study was to determine the acute effect of passive heat exposure (PHE) on arterial stiffness, oxidative stress (OxS) and inflammatory parameters. MATERIALS AND METHODS: Subjects were studied in thermoneutral conditions before and after PHE in a climatic chamber. Pulse wave analysis was used for assessment of central hemodynamic and arterial stiffness parameters. Venous blood samples were obtained to measure OxS and inflammatory parameters...
2016: Medicina
Scott A Wooldridge, Scott F Heron, Jon E Brodie, Terence J Done, Itsara Masiri, Saskia Hinrichs
A spatial risk assessment model is developed for the Great Barrier Reef (GBR, Australia) that helps identify reef locations at higher or lower risk of coral bleaching in summer heat-wave conditions. The model confirms the considerable benefit of discriminating nutrient-enriched areas that contain corals with enlarged (suboptimal) symbiont densities for the purpose of identifying bleaching-sensitive reef locations. The benefit of the new system-level understanding is showcased in terms of: (i) improving early-warning forecasts of summer bleaching risk, (ii) explaining historical bleaching patterns, (iii) testing the bleaching-resistant quality of the current marine protected area (MPA) network (iv) identifying routinely monitored coral health attributes, such as the tissue energy reserves and skeletal growth characteristics (viz...
September 28, 2016: Marine Pollution Bulletin
Marcel Nations, Shengkai Wang, Christopher S Goldenstein, David F Davidson, Ronald K Hanson
The formation of electronically excited atomic oxygen was studied behind reflected shock waves using cavity-enhanced absorption spectroscopy. Mixtures of 1% O2-Ar were shock-heated to 5400-7500 K, and two distributed-feedback diode lasers near 777.2 and 844.6 nm were used to measure time-resolved populations of atomic oxygen's (5)S° and (3)S° electronic states, respectively. Measurements were compared with simulated population time histories obtained using two different kinetic models that accounted for thermal nonequilibrium effects: (1) a multitemperature model and (2) a reduced collisional-radiative model...
October 14, 2016: Journal of Physical Chemistry. A
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