1,968 research outputs found
Giant radiation heat transfer through the micron gaps
Near-field heat transfer between two closely spaced radiating media can
exceed in orders radiation through the interface of a single black body. This
effect is caused by exponentially decaying (evanescent) waves which form the
photon tunnel between two transparent boundaries. However, in the mid-infrared
range it holds when the gap between two media is as small as few tens of
nanometers. We propose a new paradigm of the radiation heat transfer which
makes possible the strong photon tunneling for micron thick gaps. For it the
air gap between two media should be modified, so that evanescent waves are
transformed inside it into propagating ones. This modification is achievable
using a metamaterial so that the direct thermal conductance through the
metamaterial is practically absent and the photovoltaic conversion of the
transferred heat is not altered by the metamaterial.Comment: 4 pages, 3 figure
Proximity effect of vanadium on spin-density-wave magnetism in Cr films
The spin-density wave (SDW) state in thin chromium films is well known to be
strongly affected by proximity effects from neighboring layers. To date the
main attention has been given to effects arising from exchange interactions at
interfaces. In the present work we report on combined neutron and synchrotron
scattering studies of proximity effects in Cr/V films where the boundary
condition is due to the hybridization of Cr with paramagnetic V at the
interface. We find that the V/Cr interface has a strong and long-range effect
on the polarization, period, and the N\'{e}el temperature of the SDW in rather
thick Cr films. This unusually strong effect is unexpected and not predicted by
theory.Comment: 7 figure
Fast reactor BREST-300
This paper describes the nearest future of nuclear power engineering in terms of fast reactor - BREST-300. The article shows its design, characteristics and benefits of fast reactors. Even modern reactors with slow neutrons have high energy rates, but there are some problems such as rarity of Uranium -235 and large amounts of waste. The Russian development of BREST-300 is able to solve some of the problems. Key words: BREST-300, fast reactor(FR), loop, fuel assembly (FA), closed nuclear fuel cycle (CFC), thermal power, electric power, fuel lifetime
Application of near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) in an in-situ analysis of the stability of the surface-supported metal-organic framework HKUST-1 in water, methanol and pyridine atmospheres
A review of the pesticide MCPA in the land-water environment and emerging research needs
peer-reviewedDue to its high solubility and poor adsorption to the soil matrix, the postemergence
herbicide 2-methyl-4-chlorophenoxyacetic acid (MCPA) is susceptible
to transport into surface and groundwater bodies, where it can result in
compromised water quality and breaches of legislative standards. However,
there is still poor understanding of catchment scale dynamics and transport,
particularly across heterogeneous hydrogeological settings. While it is known
that MCPA degrades under aerobic conditions, negligible breakdown can
occur in anaerobic environments, potentially creating a legacy in saturated
soils. Fast runoff pathways post application are likely transport routes, but the
relative contribution from the mobilization of legacy MCPA from anaerobic
zones has yet to be quantified, making the delineation of MCPA sources
encountered during monitoring programs challenging. While ecotoxicological
effects have been examined, little is known about the interaction of MCPA
(and its degradation products) with other pesticides, with nutrients or with colloids,
and how this combines with environmental conditions to contribute to
multiple stressor effects. We examine the state of MCPA knowledge, using case
study examples from Ireland, and consider the implications of its widespread
detection in waterbodies and drinking water supplies. Research themes
required to ensure the sustainable and safe use of MCPA in an evolving agricultural,
social and political landscape are identified here. These include the
need to identify mitigation measures and/or alternative treatments, to gain
insights into the conditions governing mobilization and attenuation, to map
pathways of migration and to identify direct, synergistic and antagonistic ecotoxicological
effects
Multiplicities of secondaries in interactions of 1.8 GeV/nucleon Fe-56 nuclei with photoemulsion and the cascade evaporation model
A nuclear photographic emulsion method was used to study the charge-state, ionization, and angular characteristics of secondaries produced in inelastic interactions of Fe-56 nuclei at 1.8 GeV/nucleon with H, CNO, and AgBr nuclei. The data obtained are compared with the results of calculations made in terms of the Dubna version of the cascade evaporation model (DCM). The DCM has been shown to satisfactorily describe most of the interaction characteristics for two nuclei in the studied reactions. At the same time, quantitative differences are observed in some cases
Target fragments in collisions of 1.8 GeV/nucleon Fe-56 nuclei with photoemulsion nuclei, and the cascade-evaporation model
Nuclear photographic emulsion is used to study the dependence of the characteristics of target-nucleus fragments on the masses and impact parameters of interacting nuclei. The data obtained are compared in all details with the calculation results made in terms of the Dubna version of the cascade-evaporation model (DCM)
Solar dynamo model with nonlocal alpha-effect
The first results of the solar dynamo model that allows for the diamagnetic
effect of inhomogeneous turbulence and the nonlocal alpha-effect due to the
rise of magnetic loops are discussed. The nonlocal alpha-effect is not subject
to the catastrophic quenching related to the conservation of magnetic helicity.
Given the diamagnetic pumping, the magnetic fields are concentrated near the
base of the convection zone, although the distributed-type model covers the
entire thickness of the convection zone. The magnetic cycle period, the
equatorial symmetry of the field, its meridional drift, and the
polar-to-toroidal field ratio obtained in the model are in agreement with
observations. There is also some disagreement with observations pointing the
ways of improving the model.Comment: To appear in Astronomy Letters, 10 pages, 5 figure
Multiplicities of secondaries in nuclear interactions, induced by Ne-20, Ar-40 and Fe-56 nuclei at 0.1-0.5 GeV/nucleon
Multiplicities of various species of charged secondaries produced in inelastic interactions of Ne-20, Ar-40, and Fe-56 nuclei with emulsion nuclei, at 0.1-0.5 GeV/nucleon have been measured. The data obtained are compared with the results for interactions of higher energy nuclei with emulsion nuclei. The dependences of the nucleus-nucleus interaction parameters on masses and energies of colliding nuclei are examined
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