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Radiative energy transfer at nanoscale distances can exceed that of blackbody radiation by several orders of magnitude due to photon tunneling and the excitation of surface polaritons. While significant progress has been made recently in understanding near-field thermal radiation, an outstanding question remains as whether there exists an upper limit of near-field radiation for arbitrarily selected material properties at finite separation distances. We investigate the maximum achievable radiative heat flux between two parallel plates separated by a vacuum gap from 0.1 to 100 nm. By assuming a frequency-independent dielectric function and introducing a cutoff parallel wavevector component, we find that the ideal dielectric function for the two media that will maximize the near-field radiative transfer is -1+iδ, where δ is the imaginary part. For vacuum gaps greater than 1 nm, the near-field heat transfer peaks when δ<1, while at subnanometer gaps, the peak in the energy transfer shifts toward larger values of δ. The determination of the maximum radiative flux at nanometer distances will benefit emerging applications of near-field radiation for energy harvesting and nanothermal manufacturing. [ABSTRACT FROM AUTHOR]

A large number of recent publications dealt with enhanced emission properties of micro/nanostructures by the excitation of surface plasmon or phonon polaritons. Some used grating structures to demonstrate coherent thermal emission in a narrow spectral band and towards a well-defined direction. Others suggested that planar layers could also be used to achieve coherent emission. In the present paper, we describe two alternative designs with fewer layers for the application as coherent emission sources in planar multilayer structures. One design is a composite of several unit cells of one-dimensional photonic crystal atop a highly reflective material. Coherent emission can be obtained by the excitation of surface waves between the photonic crystal and the reflector. The other design employs a Fabry-Pérot resonance cavity constructed by coating a dielectric layer onto the reflector and then a thin metallic film on the dielectric layer. When standing waves exist in the cavity, the emissivity plots show sharp spectral peaks and narrow angular lobes. By optimizing the film thicknesses, a close-to-unity emissivity can be achieved from the proposed structures. The theoretical predictions are supported by the measured spectral reflectance from fabricated samples. [ABSTRACT FROM AUTHOR]

With the forthcoming laser intensities (I ≥ 1023 W/cm2), synchrotron radiation in a laser-plasma interaction has attracted particular interest because it can lead to an extremely bright source of γ-rays. Here, a scheme to generate a bright γ-ray pulse with high efficiency is proposed and numerically demonstrated. Using a circularly polarized (CP) laser pulse impinged on a thin foil, a relativistic flying plasma layer is formed. With another counterpropagating CP pulse colliding with the flying layer, it is found that the electrons are efficiently accelerated in the longitudinal direction by the space-charge field. The energetic electrons interact with the counterpropagating CP pulse, producing ultra-brilliant (∼1024 photons/s/mm2/mrad2/0.1%BW) highly dense (∼270nc) femtosecond (∼5 fs) γ-ray pulses. At a moderate laser intensity of 4 × 1022 W/cm2, the fraction of laser energy transferred into the γ-ray pulse is as high as 10%, which is comparable to that previously predicted for an order of magnitude higher in laser intensity. The enhanced γ-photon emission might pave the way for its potential applications in the near future. [ABSTRACT FROM AUTHOR]

Strong coupling stimulated Brillouin backscattering (sc-SBS) in plasma is potentially an efficient method of amplifying laser pulses to reach exawatt powers. Here, we report on a new regime of brillouin-based plasma amplification, producing an amplified pulse with a duration of 5 fs and unfocused intensity of 6x1017 W/cm2. The results are obtained from 2D particle-in-cell simulations, using two circularly polarized pump and seed pulse with Gaussian transverse profile, both at an intensity of 2.74x1016 W/cm2, counter-propagating in a 0.3nc plasma. The significant compression of amplified seed is achieved as a result of sc-SBS amplification as well as additional compression by the interplay between self-phase modulation and negative group delay dispersion. We show that the amplified seed retains high beam qualities since the filamentation can be prevented due to the fast compression. This scheme may pave the way for few-cycle laser pulses to reach exawatt or even zetawatt regime. [ABSTRACT FROM AUTHOR]

Yeast species belonging to Saccharomyces have great potential for the wine industry. However, the sulphite tolerance of most S. uvarum strains is quite poor compared with that of the other Saccharomyces strains. In order to get new S. uvarum strains with tolerance to sulphite, and also with good fermentation characteristics, 21 candidates were screened from three different crossing combinations of sensitive S. uvarum strains to one sulphite-tolerant strain. Ten of these hybrids were sulphite tolerant and contained the FZF1 gene from both parents. Inter-simple sequence repeat (ISSR) analysis confirmed their hybrid status, based on six primers that produced 55 clear and reproducible bands, including 32 that were polymorphic. Two hybrids had identical fingerprints, indicating that it was the same clone. Thus, nine different novel sulphite-resistant hybrids of S. uvarum were obtained. The selected hybrid strains fermented very well at 30ºC in Sauvignon Blanc grape juice containing 2 mM of sodium sulphite, with minor differences in fermentation performance. Two strains (namely C13 and C21) performed very similarly to the sulphitetolerant parent A9 and a commercial S. cerevisiae strain EC1118, and the production of fermentation aromas, namely propanol, isobutanol and isoamyl alcohol by C13 was found to be the highest. This is the first report of using hybridisation to breed the sulphite-tolerant S. uvarum strains. [ABSTRACT FROM AUTHOR]

Broadband absorption is needed for a wide spectrum of applications such as solar–thermal conversion, radiative cooling, and photodetection. In this work, we theoretically show that trapezoidal gratings made of a natural hyperbolic material on a metal substrate can be used to achieve omnidirectional perfect absorption in a relatively broad spectral region. Hexagonal boron nitride (hBN) is taken as a mid-infrared polar material with hyperbolic characteristic in the wavelength region from 6.2 to 7.3 μm. The anisotropic rigorous-coupled wave analysis is used to calculate the absorptance as well as the local power dissipation and field distributions. The main mechanism for the broadband perfect absorption is elucidated by considering the slow-light effect in a hyperbolic waveguide, which can trap the incident light of different wavelengths in different regions of the trapezoid. The spectral range and bandwidth of near perfect absorption can be adjusted within the hyperbolic range of the material by changing the shape of the trapezoid. Moreover, the substrate can play a role on the reflectance and transmittance of the structure for the wavelengths that do not support the slow-light effect. Similar designs can be applied to other hyperbolic materials to achieve perfect absorption in various wavelength regions. [ABSTRACT FROM AUTHOR]

An instrument used for measuring multiple scintillators' light output and energy resolution was developed. The instrument consisted of a light sensor array which was composed of 64 discrete SiPMs (Silicon Photomultipliers), a corresponding individual channel readout electronics system, and a data processing algorithm. A Teflon grid and a large interval between adjacent SiPMs were employed to eliminate the optical cross talk among scintillators. The scintillators' light output was obtained by comparing with a reference sample with known light output. Given the SiPM temperature dependency and the difference among each SiPM, a temperature offset correction algorithm and a non-uniformity correction algorithm were added to the instrument. A positioning algorithm, based on nine points, was designed to evaluate the performance of a scintillator array. Tests were performed to evaluate the instrument's performance. The uniformity of 64 channels for light output measurement was better than 98%, the stability was better than 98% when temperature varied from 15 °C to 40 °C, and the nonlinearity under 511 keV was better than 2%. This instrument was capable of selecting scintillators and evaluating the packaging technology of scintillator arrays with high efficiency and accuracy. [ABSTRACT FROM AUTHOR]

Aim 5-Aminosalicylic acid is the first-line drug for mild to moderate ulcerative colitis ( UC). The most commonly used 5-aminosalicylic acid is mesalamine. Several systematic reviews have demonstrated that mesalamine is effective in inducing and maintaining remission. Efficacy, safety and adherence to once daily ( OD) and multiple daily ( MD) dosing of mesalamine for the induction and maintenance of remission in mild to moderate UC were systematically reviewed and compared. Method PubMed, Embase and the Cochrane Central Register of Controlled Trials were searched from inception to November 2014. Only randomized controlled trials were considered eligible. STATA software (version 12.0) was used to calculate the pooled risk ratios with 95% confidence interval. Results Seventeen randomized studies containing 5439 patients were identified. No significant differences were noted in comparisons between OD and MD dosing for maintenance and induction of remission. No significant differences were noted in rates of medication adherence or adverse events between OD and MD dosing. With regard to mesalamine suppository, no significant differences were noted for comparisons between dosing regimens and adverse events for induction of remission. Conclusion OD dose of mesalamine is as effective and safe as MD doses for the induction and maintenance treatment of mild to moderate UC. OD mesalamine given as a suppository can attain the same effect and safety as MD mesalamine in inducing remission of mild to moderate ulcerative colitis. [ABSTRACT FROM AUTHOR]

The article focuses on determining age of freshwater fish Abramis brama from Irtysh River in China by counting increase in its otoliths, and relationships of otolith dimensions with fish length. Topics discussed include otolith weight (OW) analysis helping in determine age of A. brama, isometric growth between the OW and fish standard length/age, lack of food resources responsible for slow growth rate, and suggestion on avoiding fishing during spawning season to enhance their growth.

The electrochemical behavior and oxide film structure of the weld of 316L/52M/A508 dissimilar metal welded joints were investigated via scanning electron microscopy (SEM), potentiodynamic polarization measurements, electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS). The electrochemical measurements revealed that the weld materials could be arranged in descending order of protectiveness of the oxide film formed on their surface; that is, Alloy52Mw>Alloy52Mb>C52M>C308. The results of EIS and XPS analyses showed that the oxide films formed on these materials were duplex-structured; this duplex structure consisted of a Cr-rich (in 52M nickel-based weld materials) or Cr/Fe-rich (in C308 stainless steel weld materials) inner layer and a Ni/Fe-rich (in 52M nickel-based weld materials) or Fe-rich (in 308 stainless steel weld materials) porous outer layer. [ABSTRACT FROM AUTHOR]

Excitation of surface plasmons enables super-Planckian thermal radiation far beyond the blackbody limit. By patterning a single layer of graphene sheet into ribbons, the closed circular dispersion of graphene plasmons is opened to become hyperbolic, leading to broadband singularities of density of states. Extremely high-k evanescent waves can now couple with hyperbolic graphene plasmons. Consequently, a giant enhancement of the near-field radiative heat flux, by more than one order of magnitude, is demonstrated in this study using rigorous numerical simulations. The findings may open promising pathways for highly efficient thermal management, energy harvesting, and subwavelength thermal imaging. [ABSTRACT FROM AUTHOR]

Many failures in nuclear safe-end dissimilar metal weld joint (DMWJ) have revealed that stress corrosion cracking (SCC) is mainly located in the weld metal (WM). Since the oxide film formed on the stainless steel during service plays an important role in SCC, this research focuses on the short time oxidation behavior of 308 L WM with different surface state in the simulated primary water of pressurized water reactors (PWRs) with 0.1 mg/L dissolved oxygen (DO). In the meanwhile, the oxidation behavior of the 316 L stainless steel with different surface state under the same environmental condition is also studied. Surface state and oxide films are analyzed using various methods. The results show that a dual layered oxide film is formed on 308L WM and 316 L surfaces. Both the cold-worked layer and the surface topography should be considered together when discussing the effects of the surface state on the morphologies of the oxide films. [ABSTRACT FROM AUTHOR]

Backward Raman amplification (BRA) in plasmas has been promoted as a means for generating ultrapowerful laser pulses. For the purpose of achieving the maximum intensities over the shortest distances, an envelope matching between the seed pulse and the amplification gain is required, i.e., the seed pulse propagates at the same velocity with the gain such that the peak of the seed pulse can always enjoy the maximum gain. However, such an envelope matching is absent in traditional BRA because in the latter the amplification gain propagates at superluminous velocity while the seed pulse propagates at the group velocity, which is less than the speed of light. It is shown here that, by using self-ionizing plasmas, the speed of the amplification gain can be well reduced to reach the envelope matching regime. This results in a favorable BRA process, in which higher saturated intensity, shorter interaction length and higher energy-transfer efficiency are achieved. [ABSTRACT FROM AUTHOR]

Graphene has attracted great attention in nanoelectronics, optics, and energy harvesting. Here, the near-field radiative heat transfer between graphene-covered corrugated silica is investigated based on the exact scattering theory. It is found that graphene can improve the radiative heat flux between silica gratings by more than one order of magnitude and alleviate the performance sensitivity to lateral shift. The underlying mechanism is mainly attributed to the improved photon tunneling of modes away from phonon resonances. Besides, coating with graphene leads to nonlocal radiative transfer that breaks Derjaguin's proximity approximation and enables corrugated silica to outperform bulk silica in near-field radiation. [ABSTRACT FROM AUTHOR]

The rolling-extrusion technique for the mass production of variable wall thickness cylinder parts is put forward to reduce the machining time and increase the material utilisation. In this process, material is formed by means of three passive rotational tools. The charge is provided by means of a pusher pushing the billet in a working space between the profiled rolls. A coupled thermal-mechanical rigid viscoplasticity FEM model for rolling-extrusion of variable wall thickness cylinder parts is developed based on the DEFORM-3D software. Then the distribution of effective strain field, temperature filed and the load during the rolling-extrusion forming process are discussed. Moreover, the influence of process parameters on the deformation uniformity is analysed, and the results show that the deformation non-uniformity of billet increases with increasing punch speed and friction factor or decreasing initial temperature of billet. In physical experiment, the press machine and a simple machine for rolling-extrusion are used to work out the parts .The results of these tests show the parts can be produced accurately by using rolling-extrusion technique. Compared with the traditional method, the material utilisation is increased by 19% with the machining time greatly reduced. [ABSTRACT FROM AUTHOR]

Spectral and directional control of thermal radiation is a challenging yet important task for a number of applications, including thermophotovoltaic energy conversion, solar energy utilization, space thermal management, and high-efficiency incandescent lamps. A number of structures have been proposed as coherent emission sources, with spectral emission peaks in well-defined directions. The grating structure has been commonly used in which coherent emission is achieved by the excitation of surface polaritons or surface waves. Along with the development of metamaterials, magnetic polaritons have also received much attention lately and have been demonstrated to be useful for controlling the radiative properties of periodic structures. Furthermore, planar structures can also support surface waves or optical resonance for thermal emission control, such as the truncated one-dimensional photonic crystals and asymmetric Fabry–Perot structures. This article provides an overview of theoretical and experimental research activities, performed in the Nanoscale Thermal Radiation Lab at the Georgia Institute of Technology, on tailoring the spectral and directional thermal radiative properties. [ABSTRACT FROM AUTHOR]

Thermal rectification has recently attracted great attention because it could allow heat to flow in a preferred direction and may have promising applications in thermal management and energy systems. In addition to phonon engineering, photon transport at the near-field regime has been recently proposed to realize thermal rectification between planar structures. In the present study, the thermal rectification effect enabled by near-field thermal radiation between intrinsic silicon and other materials was investigated at various temperatures and vacuum gap distances. Strong thermal rectification between intrinsic Si and doped Si (rectificationR = 2.7) and between intrinsic Si and SiO2(R = 9.9) can be achieved with a 5 nm vacuum gap at temperatures of 1000 and 300 K. Rectification larger than one can be obtained in sub-10 nm vacuum gaps for the former configuration and sub-20 nm gaps for the latter configuration. A thermal rectifier made of gold and intrinsic Si is shown to have a rectification factor around 0.85 with temperatures of 600 and 300 K at a wide range of vacuum gaps from 100 to 500 nm. The physical mechanisms of the rectification effect in the three configurations are elucidated, and each of the proposed thermal rectifiers may have its own advantage for applications dealing with different temperatures and vacuum distances. [ABSTRACT FROM AUTHOR]

Background:Emerging evidence has demonstrated that lysine-specific demethylase 1 (LSD1) has an important role in many pathological processes of cancer cells, such as carcinogenesis, proliferation and metastasis. In this study, we characterised the role and molecular mechanisms of LSD1 in proliferation and metastasis of colon cancer.Methods:We evaluated the correlation of LSD1, CDH-1 and CDH-2 with invasiveness of colon cancer cells, and investigated the roles of LSD1 in proliferation, invasion and apoptosis of colon cancer cells. We further investigated the mechanisms of LSD1-mediated metastasis of colon cancer.Results:Lysine-specific demethylase 1 was upregulated in colon cancer tissues, and the high LSD1 expression was significantly associated with tumour-node-metastasis (TNM) stages and distant metastasis. Functionally, inhibition of LSD1 impaired proliferation and invasiveness, and induced apoptosis of colon cancer cells in vitro. The LSD1 physically interacted with the promoter of CDH-1 and decreased dimethyl histone H3 lysine 4 (H3K4) at this region, downregulated CDH-1 expression, and consequently contributed to colon cancer metastasis.Conclusion:Lysine-specific demethylase 1 downregulates the expression of CDH-1 by epigenetic modification, and consequently promotes metastasis of colon cancer cells. The LSD1 antagonists might be a useful strategy to suppress metastasis of colon cancer. [ABSTRACT FROM AUTHOR]

The Central Asian Orogenic Belt (CAOB) is one of the largest accretionary collages in the world, and records a prolonged sequence of subduction-accretion and collision processes. The Tarim Craton is located at the southernmost margin of the CAOB. In this study, the discovery of early Palaeozoic high-pressure (HP) granulites from the Dunhuang block in the northeastern Tarim Craton is reported, and these rocks are characterized through detailed petrological and geochronological studies. The peak mineral assemblage of the HP mafic granulite is garnet + clinopyroxene + plagioclase + quartz + rutile, which is overprinted by amphibolite facies retrograde metamorphic assemblages. The calculated P-T conditions of the peak metamorphism are ∼1.4-1.7 GPa and ∼800 °C. The retrograde P-T conditions are ∼0.7 GPa and ∼700 °C. The metamorphic zircon grains from the HP mafic granulite show homogeneous CL-images, low Th/U ratios and flat HREE patterns and yield a weighted mean 206Pb/238U age of 444 ± 5 Ma. The metamorphic zircon grains from the associated kyanite-bearing garnet gneiss and garnet-mica schist show a similar 206Pb/238U age of 429 ± 3 and 435 ± 4 Ma, respectively. The c. 440-430 Ma age is interpreted to mark the timing of HP granulite facies metamorphism in the Dunhuang block. The results from this study suggest that the Dunhuang block experienced continental subduction prior to the early Palaeozoic collisional orogeny between the northeastern Tarim Craton and the southern CAOB, and the Dunhuang area could be considered as the southward extension of the CAOB. It is suggested that the continental collision in the eastern part involving the Dunhuang block of the southern CAOB may have occurred c. 120 Ma earlier than in the western part involving the Tianshan orogen. [ABSTRACT FROM AUTHOR]

SiGe alloys represent an important type of high-temperature semiconductor material for solid-state energy conversion. In the present study, the near-field radiative heat transfer between heavily doped SiGe plates is investigated. A dielectric function model is formulated based on the previously reported room-temperature mobility and temperature-dependent electric resistivity of several silicon-rich alloys with different doping type and concentration. Fluctuational electrodynamics is used to evaluate the near-field noncontact heat transfer coefficient. The variation of the heat transfer coefficient with doping concentration and temperature is explained according to the change in the optical constants and in the spectral distribution of the near-field heat flux. [ABSTRACT FROM AUTHOR]

A complex target (CT) configuration tailored for generating high quality proton bunch by circularly polarized laser pulses at intensities of 1020-21 W/cm2 is proposed. Two-dimensional particle-in-cell simulations show that both the collimation and mono-energetic qualities of the accelerated proton bunch obtained using a front-shaped thin foil can be greatly enhanced by the backside inhomogeneous plasma layer. The main mechanisms for improving the accelerated protons are identified and discussed. These include stabilization of the photon cavity, providing hole-boring supplementary acceleration and suppressing the thermal-electron effects. A theory for tailoring the CT parameters is also presented. [ABSTRACT FROM AUTHOR]

The Jiangzhuang ultrahigh-pressure (UHP) metamorphic peridotite from south Sulu, eastern China occurs as a layer within gneiss with eclogite blocks, and consists of coarse-grained garnet porphyroblasts and a fine-grained matrix assemblage of garnet + forsterite + enstatite + diopside ± phlogopite ± Ti-clinohumite ± magnesite. Both types of garnet are characterized by high MgO content and depletion of light rare earth element (LREE) and enrichment of heavy rare earth element, but the matrix garnet has lower MgO, TiO2 and higher Cr2O3 and REE contents. Diopside displays LREE enrichment, and has low but variable large-ion lithophile element (LILE) contents. Phlogopite is a major carrier of LILE. Ti-clinohumite contains high Nb, Ta, Cr, Ni, V and Co contents. The P-T conditions of 4.5-6.0 GPa and 850-950 °C were estimated for matrix mineral assemblages. Most peridotites are depleted in Al2O3, CaO and TiO2, and enriched in SiO2, K2O, REE and LILE. In contrast to phlogopite-free peridotites, the phlogopite-bearing peridotites have higher K2O, Zr, REE and LILE contents. Zircon occurs only in the phlogopite-bearing peridotites, shows no zoning, with low REE contents and Th/U ratios, and yields tight U -Pb ages of 225-220 Ma, indicating the peridotites experienced consistent Triassic UHP metamorphism with subducted supercrustal rocks. These data demonstrate that the Jiangzhuang peridotites were derived from the depleted mantle wedge of the North China Craton, and experienced various degrees of metasomatism. The phlogopite-free peridotites may have been subjected to an early cryptic metasomatism at UHP conditions of the mantle wedge, whereas the phlogopite-bearing peridotites were subjected to a subsequent strong metasomatism, characterized by distinctly enrichment in LILE, LREE, Zr and K as well as the growth of zircon and volatile-bearing minerals at UHP subduction conditions. The related metasomatism may have resulted from the filtration of fluids sourced mainly from deeply subducted supracrustal rocks. [ABSTRACT FROM AUTHOR]