bluuebunny/crossref_metadata_2025_split huggingface dataset:
New Composite Material Based on Heavy Concrete and Basalt-Boron Fiber for Neutron Radiation Shielding Properties
Authors: Romanenko I. , Holiuk M. , Nosovsky A. , Vlasenko T. , Gulik V. 
Published: June 2019

It is necessary to have reliable radiation protection for safe operation of different radiation sources. Radiation shielding properties have been studied for a long time both in our country and abroad. However, there is a strong necessity to develop new composite materials, which will provide protection against radiation and have improved mechanical and economic characteristics.
The paper describes a new composite material for neutron radiation shielding properties based on heavy concrete with serpentinite aggregate and with basalt-boron fiber with different concentrations of fiber boron oxide for using in biological shielding in nuclear industry. Protective properties of the new composite material were investigated with different neutron sources: 1) neutrons with 14 MeV energy; 2) fast fission neutrons for U-235; 3) fast fission neutrons for U-235 after passing a water layer. The simulation of the neutron radiation in presented composite material with adding crushed stone aggregate and serpentinite aggregate is performed by Monte Carlo Serpent code.
It is shown that basalt-boron fibers in concrete improve the protective properties of concrete against neutron irradiation for neutrons with different energies, but the most effective is the addition of a basalt-boron fiber in the case of thermal neutrons.
This research was supported by Horizon 2020 ERA-NET Support Programme, Research Grant Agreement No 7.9-3/18/7 (“Development of Boron-Infused Basalt-Fiber Reinforced Concrete for Nuclear and Radioactive Waste Management Applications”). Implementation of activities described in the Roadmap to Fusion during Horizon 2020 through a joint programme of the members of the EUROfusion consortium (2014-2020), Work Package PMI. Also, this research was carried out with the financial support of the IAEA, within the terms and conditions of the Research Contract20638 in the framework of the Coordinated Research Project (CRP) “Accelerator Driven Systems (ADS) Applications and Use of Low-Enriched Uranium in ADS (T33002)’’ within the Project “The Two-Zone Subcritical Systems with Fast and Thermal Neutron Spectra for Transmutation of Minor Actinides and Long-Lived Fission Products”.
The Problem of Biological Obstacles in the Operation of Nuclear Power Plants (Illustrated by the Operation of Zaporizhzhya NPP Techno-Ecosystem)
Authors: Fedonenko O. , Marenkov O. , Petrovsky O. 
Published: June 2019

The article shows the research results on biological obstacles of the Zaporizhzhya NPP cooling pond, which may be harmful for the technological cycles of the plant or even cause emergency in the NPP.
This problem is particular importance for cooling water reservoir of energy objects, since the increased temperature regime in such reservoirs creates favorable conditions for the mass development of certain types of hydrobionts, which hinder the operation of hydraulic structures.
It was established that for the studied cooling water reservoir of Zaporizhzhya NPP all types of biological barriers that are found in technical reservoirs of nuclear power plants of Ukraine are characteristic.
It has been established that all types of biological obstacles found in technical reservoirs of nuclear power plants of Ukraine are common for the researched reservoir.
The most common are biological obstacles of bacterial, plant and animal origin. Plant biological obstacles are represented by the excessive growth of blue-green algae, which in the summer cause the "water blooming" of the cooling pond, and the filamentous algae that form thickets on the surfaces of concrete slabs and hydraulic structures. Animal biomarkers include the rapid spread of the mollusks of the Thiaridae family, which were accidentally inhabited into the water reservoir and caused massive fouling of the water development facilities of the NPP.
One of the areas of biological control of biological barriers in a Zaporizhzhya NPP cooling water reservoir is ichthyomelioration – biomeliorative release the fish into the reservoir As fish occupy higher trophic levels in aquatic ecosystems, they accumulate organic matter from other trophic units and can inhibit the massive development of hydrobionts.
The presented scientific results formed the basis of "Technological substantiation of the biological method of reducing the amount of phytoplankton and mollusks in the hydraulic engineering system of the ZNPP and conducting biomeliorative works using biomeliorative fish for the period2018-2022", the observance of which allows partial resolution of the problems of biological barriers caused by the mass development of certain species.
Effect of Gamma Irradiation of Local Brachiaria Ruziziensis (Germain & Evrard) Seeds on Agronomic Performance and Yield
Authors: Hoka Ann I. , Gicheru Michael , Otieno Syprine , Korir Hezekiah 
Published: June 2019

Appropriate methods of mutation induction are of high importance in pastures for increased genetic variability and improved performance. The objective of this research was to improve the agronomic and nutritive performance of mutant lines (M7) through induced mutagenesis to seeds of a local landrace Brachiaria ruziziensis. The seeds were irradiated with 0, 10, 20, 30 and 40Gy doses of gamma radiation from Cobalt 60 (60Co). Treatments were; KE 0Gy, KE 10Gy, KE 20Gy, KE 30Gy and KE 40Gy resulting into M1 seeds. The M1 seeds were planted in the greenhouse in germination pots for one month and the seedlings transplanted to the field. Seeds of M6 plants (M7 seeds) were used to establish field experiment in a completely randomized block design, with three replications. Parameters measured included; tillering, leaf-stem ratio, dry matter weight, and seed weight. Data collected was analyzed using the SAS package. Mutant lines exhibited better agronomic performance compared to the wild type. Performance increased with increased gamma-ray exposure with 40Gy treatment outperforming all other treatments whereas the control performed dismally. There was a significant difference (P0.05) in the dry matter with 40Gy treatment having the highest values of dry matter yields, whereas control had the lowest values. Application of nuclear technology to other grasses would lead to increased biomass and improved nutrition for increased animal productivity leading to food and nutrition security.
X-Ray anomalous transmission and topography of impurity clustering in perfect crystals
Authors: Patel Jamstred R. 
Published: June 2019

In anomalous transmission two plane waves of X-ray intensity are coupled in the crystal. Their interaction produces nodes in intensity coincident with atomic planes. When this occurs there is a very large reduction in the intensity of photoelectric absorption and à corresponding increase in the amount of transmitted X-rays. Any deformation of the lattice which moves atoms away from the atomic planes will reduce the intensity transmitted. Experiments on initially highly perfect heat treated silicon crystals show that the intensity of anomalous transmission can be reduced to zero even in crystals presumably free of oxygen.
The kinetics of the heat treatment effect depend on the initial concentration of oxygen in the crystal. More recently carefully grown crystals in which care had been taken to exclude oxygen show no decrease in anomalous transmission after heating at 1 000° C. These experiments allow us to conclude that the effects observed earlier are due to oxygen and not to vacancies or other impurities. In all cases the initial perfection of the crystal can be restored by heating at 1 350° C to dissolve the clustered oxygen.
The effects of the heat treatment have been followed by X-ray topography. The importance of section topographs in studies of this nature will be discussed. The treatment at 1 000° C produced dark unresolved contrast on X-ray section topographs and leads to a rapid obliteration of the normal Pendellösung fringe patterns observed in perfect crystals. Higher temperature heat treatment at 1 200° C produces two main types of defects that can be easily resolved by X-ray topography : prismatic dislocation loops and stacking faults. The topographic evidence for these defects will be briefly described. The X-ray topographic work is consistent with earlier results by transmission electron microscopy which reveal the same kind of defects on a much smaller scale. The anomalous transmission and the topographic results are compared with recent theory which ascribes the reduced anomalous transmission intensity to increased photoelectric and diffuse scattering absorption.
Structures lamellaires : méthodes d'étude de leurs imperfections
Authors: Gatineau Lucien , Tchoubar Denise , Méring Jacques 
Published: June 2019

Les corps à structure lamellaire se caractérisent par une très forte anisotropie. Dans l'interprétation des diagrammes de diffusion des rayons X et des électrons cette anisotropie de structure facilite la détection des imperfections cristallines. Celles-ci peuvent affecter soit le mode d'empilement des couches entre elles, soit la périodicité au sein de la couche élémentaire.
Les exemples présentés concernent les imperfections structurales dans les phyllosilicates et dans les carbones.
Résonance paramagnétique électronique de cokes prégraphitiques caractérisés par leurs taux d'interstitiels
Authors: Estrade-Szwarckopf Henriette 
Published: June 2019

In a partially graphitized carbon, the interstitial atoms of carbon, fixed on both faces of the elementary layers, prevent the tridimensional organization of those layers and define most of the mechanical and structural properties.
In this report we tried to observe the influence of those interstitial atoms on an electronic property, the E. P. R.
They can play two roles : they are either localized paramagnetic centers either electron traps. In both hypothesis, the paramagnetic susceptibility has to be sensitive to their number.
We have observed this sensitivity in studying two series of carbons, defined by their initial rate t of interstitial atoms (petroleum coke t < 2 % that can't be observed, pitch coke t ~ 10 %).
For all the studied samples, the role of electron traps has been confirmed. Their is a big difference between the two series for both the value of the massic paramagnetic susceptibility and the form and width of the E. P. R. lines.
In first approximation the results can be explained by the evolution of the electronic band populations of the carbons during the graphitization.
Those populations are modified by the presence of the interstitial carbons whose gradual elimination allows the constitution of the semi-metal structure of graphite.
Propriétés thermiques des verres aux très basses températures
Authors: Lasjaunias J. C. 
Published: June 2019

On analyse les propriétés thermiques (chaleur spécifique et conductibilité thermique) de quelques systèmes vitreux (Se, SiO₂ et GeO₂) entre 1 K et la température ambiante, grâce à un modèle de diffusion résonnante des phonons par des modes localisés de basses fréquences. De plus, aux températures inférieures à 1 K, la chaleur spécifique présente un large écart par rapport à la loi en T³ attendue.
Dr. Oszkár Tóth awarded by „Antal Gulyás medallion for crop protection“ in 2011 (laudation)
Authors: György Kövics  
Published: June 2019

The Public Utility for Development of Crop Protection Teaching (NOFKA) and The Hajdú-Bihar County Regional Association of Hungarian Chamber of Crop Protection Specialists and Plant Doctors (Chamber) established a joined Award Committee in September of 2011, which intend to serve as moral appreciation to prominent persons with excellent achievements by awarding the „Antal Gulyás medallion for crop protection” which are available for outstanding teachers, researchers, and practical crop protection specialists. The biography of late Antal Gulyás distinguished professor of plant pathology is available in a separate article of this issue. The first person to be decorated with the „Antal Gulyás medallion for crop protection” is Dr Oszkár Tóth retired reader of plant pathology for his excellence in teaching crop protection. Dr Oszkár Tóth had been involved in teaching - by delivering both lectures and practical lessons - crop protection, namely plant pathology in the legal predecessor institute of Debrecen University for more than 30 years where generations of crop protection specialists were encouraged to get a thorough knowledge in plant pathology. The one-time students of the splendid teacher welcome and congratulate to the award, moreover wish him peaceful and happy years.
A Joint Deconvolution Algorithm to Combine Single-dish and Interferometer Data for Wideband Multiterm and Mosaic Imaging
Authors: Rau Urvashi , Naik Nikhil , Braun Timothy 
Published: June 2019

Abstract
Imaging in radio astronomy is usually carried out with a single-dish radio telescope doing a raster scan of a region of the sky or with an interferometer that samples the visibility function of the sky brightness. Mosaic observations are the current standard for imaging large fields of view with an interferometer, and multifrequency observations are now routinely carried out with both types of telescopes to increase the continuum imaging sensitivity and probe spectral structure. This paper describes an algorithm to combine wideband data from these two types of telescopes in a joint iterative reconstruction scheme that can be applied to spectral cube or wideband multiterm imaging both for narrow fields of view and for mosaics. Our results demonstrate the ability to prevent instabilities and errors that typically arise when wideband or joint mosaicking algorithms are presented with spatial and spectral structure that is inadequately sampled by the interferometer alone. For comparable noise levels in the single-dish and interferometer data, the numerical behavior of this algorithm is expected to be similar to the idea of generating artificial visibilities from single-dish data. However, our discussed implementation is simpler and more flexible in terms of applying relative data weighting schemes to match noise levels while preserving flux accuracy, fits within standard iterative image reconstruction frameworks, is fully compatible with wide-field and joint mosaicking gridding algorithms that apply corrections specific to the interferometer data, and may be configured to enable spectral cube and wideband multiterm deconvolution for single-dish data alone.
Gravity, Magnetic Field, and Turbulence: Relative Importance and Impact on Fragmentation in the Infrared Dark Cloud G34.43+00.24
Authors: Tang Ya-Wen , Koch Patrick M. , Peretto Nicolas , Novak Giles , Duarte-Cabral Ana , Chapman Nicholas L. , Hsieh Pei-Ying , Yen Hsi-Wei 
Published: June 2019

Abstract
We investigate the interplay between magnetic (B) field, gravity, and turbulence in the fragmentation process of cores within the filamentary infrared dark cloud G34.43+00.24. We observe the magnetic field morphology across G34.43, traced with thermal dust polarization at 350 μm with an angular resolution of 10″ (0.18 pc), and compare with the kinematics obtained from N2H+ across the filament. We derive local velocity gradients from N2H+, tracing motion in the plane of sky, and compare with the observed local B field orientations in the plane of sky. The B field orientations are found to be perpendicular to the long axis of the filament toward the MM1 and MM2 ridge, suggesting that the B field can guide material toward the filament. Toward MM3, the B field orientations appear more parallel to the filament and aligned with the elongated core of MM3, indicating a different role of the B field. In addition to a large-scale east–west velocity gradient, we find a close alignment between local B field orientations and local velocity gradients toward the MM1/MM2 ridge. This local correlation in alignment suggests that gas motions are influenced by the B field morphology or vice versa. Additionally, this alignment seems to become even closer with increasing integrated emission in N2H+, possibly indicating that a growing gravitational pull alignes the B field and gas motion more and more. We analyze and quantify B field, gravity, turbulence, and their relative importance toward the MM1, MM2, and MM3 regions with various techniques over two scales, a larger clump area at 2 pc scale and the smaller core area at 0.6 pc scale. While gravitational energy, B field, and turbulent pressure all grow systematically from large to small scale, the ratios among the three constituents clearly develop differently over scale. We propose that this varying relative importance between B field, gravity, and turbulence over scale drives and explains the different fragmentation types seen at subparsec scale (no fragmentation in MM1; aligned fragmentation in MM2; clustered fragmentation in MM3). We discuss uncertainties, subtleties, and the robustness of our conclusion, and we stress that a multiscale joint analysis is required to understand the dynamics in these systems.
1D Magnetodynamic Simulations of Force-free Fields around a Rapidly Rotating Black Hole via Nonradial Magnetic Surfaces along the Equatorial Plane
Authors: Imamura Tomoki , Koide Shinji 
Published: June 2019

Abstract
Numerical simulations of 1D force-free magnetodynamics (FFMD) by Koide and Imamura showed details of the energy extraction mechanism around a rapidly spinning black hole under the force-free condition in the case of a radial magnetic surface along the equatorial plane. The energy is transported like a tsunami from the ergosphere and spreads to the outside. In this paper, we perform 1D FFMD simulations with nonradial magnetic surfaces along the equatorial plane, which are more general magnetic surface configurations. Using the results of simulations and analytic solutions of the steady-state force-free magnetic field, we find that, except in the case of a radial magnetic surface at infinity, the tsunami induced at the neighborhood of the horizon damps gradually and energy flux along the equatorial plane vanishes after a long period of time or at infinity. This suggests the energy extracted from the spinning black hole through the nonradial magnetic field is transported toward the high latitude around the axis of the black hole and is converted to the kinetic energy of the jet or outflow.
Star Formation Histories of the LEGUS Spiral Galaxies. I. The Flocculent Spiral NGC 7793∗
Authors: Sacchi E. , Cignoni M. , Aloisi A. , Tosi M. , Adamo A. , Dale D. A. , Elmegreen B. G. , Elmegreen D. M. , Calzetti D. , Gouliermis D. A. , Grasha K. , Smith L. J. , Wofford A. , Lee J. C. , Sabbi E. , Ubeda L. 
Published: June 2019

Abstract
We present a detailed study of the flocculent spiral galaxy NGC 7793, part of the Sculptor group. By analyzing the resolved stellar populations of the galaxy, located at a distance of ∼3.7 Mpc, we infer for the first time its radial star formation history (SFH) from Hubble Space Telescope photometry, thanks to both archival and new data from the Legacy ExtraGalactic UV Survey. We determine an average star formation rate (SFR) for the galaxy portion covered by our F555W and F814W data of 0.23 ± 0.02 M
⊙ yr−1 over the whole Hubble time, corresponding to a total stellar mass of (3.09 ± 0.33) × 109
M
⊙, in agreement with previous determinations. Thanks to the new data extending to the F336W band, we are able to analyze the youngest stellar populations with a higher time resolution. Most importantly, we recover the resolved SFH in different radial regions of the galaxy; this shows an indication of a growing trend of the present-to-past SFR ratio, increasing from internal to more external regions, supporting previous findings of the inside-out growth of the galaxy.
Intense C iv and He ii Emission in z ∼ 0 Galaxies: Probing High-energy Ionizing Photons∗
Authors: Berg Danielle A. , Chisholm John , Erb Dawn K. , Pogge Richard , Henry Alaina , Olivier Grace M. 
Published: June 2019

Abstract
In the last few years, prominent high-ionization nebular emission lines (i.e., O iii], C iii], C iv, and He ii) have been observed in the deep UV spectra of z ∼ 5–7 galaxies, indicating that extreme radiation fields characterize reionization-era systems. These lines have been linked to the leakage of Lyman continuum photons (necessary for reionization) both theoretically and observationally. Consequently, high-ionization UV emission lines present our best probe to detect and characterize the most distant galaxies that we will observe in the coming years, and are key to understanding the sources of reionization, yet the physics governing their production is poorly understood. Here we present recent high-resolution Hubble Space Telescope spectra of two nearby extreme UV emission-line galaxies, J104457 and J141851. We report the first observations of intense nebular He ii and double-peaked, resonantly scattered C iv emission, a combination that suggests these galaxies both produce and transmit a significant number of very high-energy ionizing photons (E > 47.89 eV) through relatively low column densities of high-ionization gas. This suggests that, in addition to photons at the H-ionizing edge, the very hard ionizing photons that escape from these galaxies may provide a secondary source of ionization that is currently unconstrained observationally. Simultaneous radiative transfer models of Lyα and C iv are needed to understand how ionizing radiation is transmitted through both low- and high-ionization gas. Future rest-frame far-UV observations of galaxies within the epoch of reionization using the James Webb Space Telescope or extremely large telescopes (ELTs) will allow us to constrain the escape of helium-ionizing photons and provide an estimate for their contribution to the reionization budget.
Discovery of An au-scale Excess in Millimeter Emission from the Protoplanetary Disk around TW Hya
Authors: Tsukagoshi Takashi , Muto Takayuki , Nomura Hideko , Kawabe Ryohei , Kanagawa Kazuhiro D. , Okuzumi Satoshi , Ida Shigeru , Walsh Catherine , Millar Tom J. , Takahashi Sanemichi Z. , Hashimoto Jun , Uyama Taichi , Tamura Motohide 
Published: June 2019

Abstract
We report the detection of an excess in dust continuum emission at 233 GHz (1.3 mm in wavelength) in the protoplanetary disk (PPD) around TW Hya revealed through high-sensitivity observations at ∼3 au resolution with the Atacama Large Millimeter/submillimeter Array. The sensitivity of the 233 GHz image has been improved by a factor of 3 with regard to that of our previous cycle 3 observations. The overall structure is mostly axisymmetric, and there are apparent gaps at 25 and 41 au as previously reported. The most remarkable new finding is a few astronomical-unit-scale excess emission in the southwest part of the PPD. The excess emission is located at 52 au from the disk center and is 1.5 times brighter than the surrounding PPD at a significance of 12σ. We performed a visibility fitting to the extracted emission after subtracting the axisymmetric PPD emission and found that the inferred size and the total flux density of the excess emission are 4.4 × 1.0 au and 250 μJy, respectively. The dust mass of the excess emission corresponds to 0.03 M
⊕ if a dust temperature of 18 K is assumed. Because the excess emission can also be marginally identified in the Band 7 image at almost the same position, the feature is unlikely to be a background source. The excess emission can be explained by a dust clump accumulated in a small elongated vortex or a massive circumplanetary disk around a Neptune-mass-forming planet.