bluuebunny/crossref_metadata_2025 huggingface dataset:
An overview of health hazards of volatile organic compounds regulated as indoor air pollutants
Authors: Tsai Wen-Tien
Published: December 2018

Indoor air quality (IAQ) standards and guidelines for volatile organic compounds (VOCs) have been stipulated by various national and international agencies. The main purpose of this paper is to establish an overview of indoor VOCs regarding their impacts on human health. Herein, 13 VOCs were designated as indoor air pollutants (IAPs) in the IAQ standards and guidelines. They were further grouped into four types: nonchlorinated aromatic compounds, chlorinated aromatic compounds, chlorinated aliphatic compounds and aldehydes. For this purpose, the present study discusses the criteria for designating VOCs, and summarizes their main sources in indoor environments. Because the occupational exposure limit (OEL) in workplaces has often used as a preliminary basis for establishing acceptable health-based IAQ guidelines in buildings and residences, this paper thus reviews the OEL values, especially in the American Conference of Governmental Industrial Hygienists (ACGIH)-threshold limit value (TLV). In addition, this paper also reviews the information about the classification of carcinogenicity in human by the international agencies for these VOCs. It shows that human tissues, including kidney, liver, leukemia, nasal cavity, paranasal sinus, liver and bile duct, could be more involved in the development of cancers or tumors when people are exposed to these VOCs through inhalation route in buildings over a long period of time.
Photoluminescence, Third-Order Nonlinear Optical and DFT Studies of Hydrazonium L-Tartrate – Combined Experimental and Theoretical Studies
Authors: Kannan Vadivelu , Karthick Subramani , Brahadeeswaran Srinivasan
Published: December 2018

Isothermal solvent evaporation method was employed to grow Undeuterated Hydrazonium L-tartrate (HLT) single crystals using water:methanol (5:1) solution as a solvent. The proton and carbon positions of HLT have been revealed by 1H and 13C NMR spectrum, respectively. The energy emission behaviour of HLT were analysed by photoluminescence spectrum. The nonlinear refractive index (n2), nonlinear absorption coefficient (β) and third order nonlinear susceptibility (χ
3) of HLT single crystal were determined by adapting Z-scan technique. Quantum chemical calculations on HLT was carried out by DFT using B3LYP/6-311++G(d,p) basis set. The predicted first hyperpolarizability of HLT is found to be 1.09 times greater than that of urea and suggests that HLT could be an attractive material for NLO applications. The predicted HOMO-LUMO energies of HLT confirmed that charge transfers occur within the molecule. The molecular bond strength and stability of the title compound were analysed by employing NBO analysis. The other molecular properties such as Mulliken atomic charge, ESP map, thermodynamic functions and perturbation theory energy have also been investigated. These investigations have been carried out for the first time, to the best our knowledge, in order to study the nonlinear optical properties of HLT and to enhance its usefulness for NLO applications.
Thermal and Rheological Study of Nanocomposites, Reinforced with Bi-Phase Ceramic Nanoparticles
Authors: Khattak Noor Saeed , Ahmad Arbab Safeer , Shah Luqman Ali , Ara Latafat , Farooq Muhammad , Sohail Muhammad , Kader Safaa I.
Published: December 2018

In this study the synthesis of bi-phase nanoparticles of Fe1.46Zn0.5La0.04Cu0.5O4 (FZLCs) ceramics were first carried out by Sol-gel method and then nanocomposites of FZLCs with polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA), polyethylene glycol (PEG) and polyethylene oxide (PEO) were prepared by one-pot blending technique. XRD, FT-IR, TG/DTA and SEM techniques were applied for complete characterization of composites. Rheological and dielectric properties of all nanocomposites were studied in detail for their comparative performance. TGA results reveal the highly thermal stability for all nanocomposites in this order i.e. FLZCs/PEO > FLZCs/PVA > FZLCs/PVP > FZLCs/PEG. Rheological properties show that these materials are rigid, pseudo plastic and non-Newtonian in nature. The increase in values for storage modulus (G′) and loss modulus (G′′) with increasing angular frequency owed to the shear thinning behavior of these nanocomposites. Dielectric properties show good agreement to that of energy storage substances which means that these materials have potential to be applied in storage devices.
Structural and Optical Properties of Multilayer Heterostructure of CdTe/CdSe Thin Films
Authors: Majid Farzana , Malik Abdul , Ata Sadia , Hussain Zaheer , Bibi Ismat , Iqbal Munawar , Rafay Muhammad , Rizvi Hina
Published: December 2018

CdTe/CdSe multilayer heterostructures thin films were prepared by thermal evaporation method. The CdTe/CdSe layers deposited on glass substrate and effects of annealing temperature on optical and structural properties of thin films were investigated. The XRD analysis revealed that CdTe and CdSe were in cubic (111) and hexagonal (100) forms. By increasing the annealing temperature, intensity of XRD peaks increased for multilayer heterostructures. Band alignment in heterostructures of CdTe/CdSe was of type II. Energy band gaps values for CdTe/CdSe multilayer heterostructures increased with respect to bulk compounds. During emission, red and blue shifts are observed in visible region in photoluminescence spectrum of CdTe/CdSe samples. Due to better crystallinity of multilayer thin film, 1LO, 2LO and 3LO phonon modes were observed in Raman spectrum.
Reactor Dosimetry: 16th International Symposium
Authors: Sparks Mary Helen , DePriest K. Russell , Vehar David W.
Published: December 2018

Description

Get the latest information on databases, benchmark studies, techniques, and standardization of radiation metrology and regulatory information related to reactor dosimetry.

Learn more about modern technologies used in radiation imaging and the development of radiation instrumentation. Plus you’ll get over 50 peer-reviewed papers covering related new work in

Researchers, educators, manufacturers, regulators, and industry and utilities workers will benefit from this important research presented at the Sixteenth International Symposium on Reactor Dosimetry (ISRD) held in May 2017.
Co-60 Filter Box Optimization
Authors: DePriest K. Russell , Vehar David W. , Laub Thomas W.
Published: December 2018

The measurement of photon dose in pure gamma-ray and mixed (neutron/gamma) field environments relies heavily on calibration of thermoluminescent dosimeters (TLDs) in cobalt-60 (Co-60) gamma irradiation environments. One of the principal means of reducing the gamma dose measurement uncertainty in Sandia National Laboratories’ reactor environments is careful calibration of the CaF2:Mn TLDs used in the test environment. One issue that arises is that Co-60 gamma fields used for calibration universally have a low energy photon component. The scattered photons that make up the low energy photon component are a principal source of measurement error for the TLD calibration. ASTM E1249, Standard Practice for Minimizing Dosimetry Errors in Radiation Hardness Testing of Silicon Electronic Devices Using Co-60 Sources, describes a method that utilizes photon spectrum filter boxes to enclose devices under test that can reduce the measurement error during TLD calibration as well as during normal radiation testing of electronic components in the gamma field. Using a silicon sensor representative of a CMOS-7 technology, a series of calculations was performed for single-layer, two-layer, and three-layer filters to identify a filter box that improves the silicon dose-to-kerma ratio (that is, the filter reduces the low energy photon component in the Co-60 radiation field) in the sensor over the current filter box design. The results of the parameter study in this paper will be used to plan experimental studies in the Co-60 gamma fields used for calibration.
Evaluation of the Pool Critical Assembly Benchmark with Explicitly Modeled Geometry Using MCNP6’s Unstructured Mesh Capabilities
Authors: Kulesza Joel A. , Martz Roger L.
Published: December 2018

The Oak Ridge National Laboratory pool critical assembly pressure vessel wall benchmark facility is a standard benchmark for qualifying light water reactor radiation transport methods and data. As such, it is familiar to the reactor dosimetry community and provides a convenient vehicle to introduce that community to the Monte Carlo N-Particle® code system's unstructured mesh geometry capability. An approach to model the pool critical assembly geometry using unstructured mesh and an accompanying analysis workflow that makes use of eigenvalue calculations to generate a fixed, distributed, source for the final dosimetry analysis is given. In the final analysis, the International Reactor Dosimetry and Fusion File v1.05 library is used to calculate unadjusted reaction rates. Individual foil calculation-to-experiment comparisons are usually within 10 % but are typically greater than unity, leading to an overall average calculation-to-experiment ratio of 1.10. The paper concludes with suggestions for short- and long-term future refinements that are expected to improve the agreement between calculations and experimental values.
Rigorous Uncertainty Propagation Using a Dosimetry Transfer Calibration
Authors: Griffin Patrick J. , Vehar David W. , Parma Edward J. , Hahn Kelly D.
Published: December 2018

The process of determining the uncertainty in the neutron fluence from the measured activity of a dosimetry monitor is reviewed and the importance of treating the energy-dependent correlation is illustrated using several representative neutron fields. The process of determining the uncertainty in the neutron fluence when a transfer calibration is used is then detailed. The conversion factor, when a transfer calibration is used, has a term that has an integral over the cross section appearing in both the numerator and the denominator. This term introduces a nonlinear dependence on the cross section within the conversion factor and an explicit correlation between the terms appearing in the numerator and denominator of the conversion factor. A method for rigorously treating this nonlinear uncertainty propagation is presented. This method is based upon utilizing the covariance matrix for the cross section and utilizing a statistical sampling approach based on a Cholesky transformation of this covariance matrix. This methodology is then applied to the determination of the uncertainty from a transfer calibration for a set of nine neutron spectra based upon using the 32S(n,p)32P reaction and a transfer calibration in a 252Cf standard benchmark neutron field. A very strong correlation is found in the cross-section terms as they appear in the numerator and in the denominator. When a rigorous treatment is used to propagate the uncertainty due to the cross section for the dosimetry monitor, the uncertainty in the conversion factor is reduced by a factor of more than ten times from a worst-case approach that treats the uncertainty components in the numerator and denominator as uncorrelated. This ten times difference is also seen when the comparison is made between a rigorous treatment and a treatment of the cross-section contributions where the numerator and denominator are treated as uncorrelated (i.e., when compared to a root-mean-square approach).
Exploration of the 1 keV–1 MeV Neutron Energy Range Using Zirconium Dosimeters
Authors: Thiollay Nicolas , Sergeyeva Victoria , Lyoussi Abdallah , Domergue Christophe , Destouches Christophe
Published: December 2018

The 1 keV to 1 MeV neutron energy range is of major importance for neutron spectrum reconstruction at any particular location in a reactor. Typical applications may be neutron flux assessment in order to anticipate embrittlement of pressure water reactor vessels, study of material damage under high–dose irradiation in materials testing reactors, or experimental data for feedback on various cross-section evaluations. Up to now, thermal and fast ranges of the neutron spectrum could be determined accurately by using dosimeters with adequate energy sensitivity. However, there is no proper dosimeter to investigate the intermediate energy domain. The purpose of this paper is to demonstrate the possibility of detecting the neutron flux between 1 keV and 1 MeV by irradiating zirconium-92 (92Zr) and 94Zr samples under a boron nitride filter, which reduces thermal neutron contribution. This article describes a specific irradiation of zirconium dosimeters as well as experimental results obtained by gamma spectrometry or accelerator mass spectrometry. This irradiation is simulated with the TRIPOLI-4® Monte-Carlo neutron transport code. Nuclear reactions of interest are 94Zr(n, γ)95Zr→niobium-95 (95Nb)→molybdenum-95 (95Mo) (stable) and 92Zr(n, γ)93Zr (quasi-stable). Experimental values of 95Zr activity and 93Zr/92Zr isotopic ratio are compared to calculation results. After reviewing all available evaluations for nuclear data, a comparison is made using radiative capture cross sections from the Evaluated Nuclear Data File, ENDF/BVII.1 that are the most accurate. Finally, uncertainties are obtained by combining those from both experimental and nuclear data. This work demonstrates the feasibility of 1 keV to 1 MeV neutron detection by using 92Zr or 94Zr(n, γ) reactions (or both) and introduces an original post–irradiation analysis for reactor dosimetry based on accelerator mass spectrometry. It also reveals that more precise evaluations of 92Zr and 94Zr(n, γ) cross sections are required in order to improve calculation/experiment values.
Simultaneous Measurements of Nuclear Heating and Thermal Neutron Flux Obtained with the CALMOS-2 Measurement Device inside the OSIRIS Reactor
Authors: Carcreff Hubert , Salmon Laurent , Lepeltier Valérie , Guyot Jean-Marie , Bouard Eric
Published: December 2018

Nuclear heating inside a materials testing reactor needs to be known in order to design irradiation experiments that have to fulfill temperature constraints. To improve nuclear heating knowledge, an innovative calorimeter, CALMOS, has been studied, manufactured, and tested for the 70-MWth OSIRIS reactor operated by the French Alternative Energies and Atomic Energy Commission. This device is based on a mobile calorimetric probe that can be inserted in any in-core location and moved axially along the core height and above. Obtained results and advantages brought by the first CALMOS-1 equipment already have been presented. However, a thermal limitation in the cell did not allow the monitoring of nuclear heating up to the nominal power, and some significant discrepancies were observed at high heating levels between results deduced from the calibration and those obtained by the “zero method.” Feedback-based, the new CALMOS-2 calorimeter has been designed both for extending the heating range up to 13 W.g-1 and for improving the “zero method” procedure. In addition, the CALMOS-2 calorimeter is an operational measurement system, suited to characterize the radiation field evolution throughout the reactor cycle. To meet this requirement, a programmable system associated with specific software allows automatic cell mobility in the core, the acquisition of data and their processing. This paper presents an analysis of results collected during the 2015 measurement campaign carried out with the new prototype. The four-wire technique was tested up to about a 4 W.g-1 heating level and allowed to quantify discrepancies between “zero” and calibration methods. Thermal neutron flux and nuclear heating measurements from CALMOS-1 and CALMOS-2 are compared. Thermal flux distributions, obtained with a self-powered neutron detector suited to the calorimeter, are compared with those obtained with current devices. Finally, the analysis emphasizes advantages brought by the human machine interface, which deeply refined the profiles definition.
Derivation of Ex-Core Detector Response Functions for Sizewell B
Authors: Murphy Christophe , Wright George A. , Thornton Dean A. , Shaw Simon E. , Bryce Paul
Published: December 2018

This paper describes neutron transport calculations carried out in order to predict the responses of the ex-core neutron detectors installed in the pressurized water reactor at Sizewell B in the UK. The calculations were performed in adjoint mode using the Monte Carlo radiation transport code MCBEND. The paper compares the new response functions with the response data used to date and tests the new response functions against the results of forward Monte Carlo calculations. It also describes the results of sensitivity calculations that underwrite key assumptions in the modeling.
Validation of MCBEND Dosimetry Predictions against Measurements from Hunterston B Advanced Gas-Cooled Reactor
Authors: Allen Dennis A. , Thornton Dean A. , Shaw Simon E. , Wagemans Jan , Whiley Geoff S. , Watson James D. , Huggon Adrian P. , Mason Paolo
Published: December 2018

The core restraints of advanced gas-cooled reactors are important structural components necessary for maintaining the geometric integrity of the cores. Neutron damage and nuclear heating rates, calculated using the Monte Carlo code MCBEND, have underpinned the safety case for continued operation of four reactors. To validate these calculations, neutron activation measurements were commissioned. A neutron flux activation “stringer” was deployed in the graphite side reflector of one of the Hunterston B reactors and irradiated for a period of approximately three years. A capsule attached to the bottom end of this cable contained a range of fast and thermal neutron activation monitor wires to provide additional spectral information. Following its successful withdrawal, measurements were undertaken at SCK-CEN’s laboratory in Mol, Belgium, to provide monitor wire activities. In parallel with this, activation calculations were undertaken by Amec Foster Wheeler using a MCBEND model tailored to the state of the reactor during the irradiation period. Time-varying neutron source data were used, decay-adjusted for the half-lives of the activation monitors, in order to accommodate the effects upon the expected activities of time-varying reactor power. Adjustments were made for neutron flux attenuation within the stringer capsule and cable and, where necessary, corrections were also made for parent and activation nuclide burnout. There was no requirement for spectral adjustment. Excellent agreement between calculated and measured activities was obtained for both fast and thermal neutron responses; the overall calculated/measured ratios were 1.14 ± 0.15 and 1.11 ± 0.12, respectively. These are sufficiently close to the desired value of unity to provide confidence in the ability of the calculation route to predict neutron damage rates within the core restraint components. This successful validation supports the case for life extension of the Hunterston B and Hinkley Point B power plants.
Numerical Experiment to Validate an Advanced Methodology for Dosimetry in French Nuclear Reactors
Authors: Thiollay Nicolas , Fausser Clément , Bourganel Stéphane , Mosca Pietro
Published: December 2018

The embrittlement monitoring in the reactor pressure vessel is of major interest for the operators of nuclear power plants. An upgrading of the procedure used to analyze dosimeters in the French surveillance capsules has been developed in the last years to improve the accuracy of the current methodology. This enhancement corresponds to the evolution of both the calculation codes and the nuclear data libraries in the last 20 years. Recent codes carry out more accurate neutron transport (TRIPOLI-4®) and depletion (DARWIN/PEPIN2) calculations and use modern cross-section data (JEFF3.1.1 and IRDF2002). This improvement goes together with the generation of a new adjustment code, CALMAR, to fit the fast calculated flux with dosimeter measurements. The validation of this upgraded methodology is partially attained comparing adjusted results with a large number of experiments available for the French pressurized water reactor fleet. Additional results are obtained with simulated “experiments” resulting from purely numerical simulations allowing one to test the robustness of the overall methodology versus input data. Information such as water density, compound expansion, steel thicknesses, water gaps, and fission spectra are investigated in order to test the capability of the methodology to find the solution even if input data are known with little accuracy. In addition, these numerical experiments aim to enrich the validation database of the CALMAR adjustment algorithm through comparisons with other adjustment codes widely used in the field of reactor dosimetry.
Vanadium Self-Powered Detector Gamma Response in Commercial Pressurized Water Reactor
Authors: Chen Jianwei
Published: December 2018

A vanadium self-powered neutron detector has been used in recently designed Westinghouse four-loop pressurized water reactor and AP1000® plants as the in-core instrumentation system detector. Vanadium has a smaller cross section when compared to rhodium and platinum self-powered neutron detectors, which allows it to have a longer lifetime in the reactor core. A vanadium detector is also known to have a measurable component of gamma response in its detector signal in addition to desired neutron response, which may prevent it from performing a load follow and online core monitoring/surveillance function for the advanced modern reactor design if this gamma response component becomes too large. In order to investigate this phenomenon, a series of detailed pressurized water reactor fuel assembly Monte Carlo N-Particle models has been built to calculate the gamma contribution fractions in fuel assemblies with various initial enrichment and burnup levels. Several experiments have been performed at the Penn State University Breazeale research reactor to measure the gamma and neutron sensitivity of the vanadium in-core detector. The gamma contribution fraction has also been measured at the Penn State University Breazeale reactor by scramming the reactor from full power and by various power maneuvers. Similar tests have also been performed at a Westinghouse four-loop reactor with a vanadium fixed in-core instrumentation system. All the results indicate that the gamma contribution fractions in the vanadium in-core detector designed by Westinghouse for commercial pressurized water reactors will perform its designed functions.
Radiation-Induced Degradation of Concrete in NPPs
Authors: Remec Igor , Rosseel Thomas M. , Field Kevin G. , Le Pape Yann
Published: December 2018

Nuclear power plant life extensions to 60 and potentially 80 years of operation have renewed interest in long-term material degradation. One material being considered is concrete. Swelling of aggregates driven by radiation-induced displacements of atoms is currently considered to be the most probable leading contributor to the radiation-induced degradation of concrete mechanical properties. In the biological shields of nuclear plants, atom displacements are dominated by neutron contributions while gamma-ray contributions are negligible. For several minerals that are common constituents of aggregates in concrete, it was shown that approximately 95 % of the displacement per atom is generated by neutrons with energies above 0.1 MeV. Neutrons with energies above 1 MeV contribute only approximately 20 % to 25 % to the displacement per atom. Therefore, if neutron fluence is used as the correlation parameter for the concrete degradation, the 0.1 MeV neutron energy cutoff should be used for the fluence. Based on the projected neutron fluence values (E > 0.1 MeV) in the concrete biological shields of the U.S. pressurized water reactor fleet and the available data on radiation effects on concrete, some decrease in mechanical properties of concrete cannot be ruled out during extended operation beyond 60 years.
Evaluation of the 23Na(N,Gamma) Reaction Cross Section
Authors: Badikov Sergei , Zolotarev Konstantin
Published: December 2018

Poor and incomplete uncertainty information for the 23Na(n,g)24Na reaction cross-section evaluation in the International Reactor Dosimetry and Fusion File, new thermal neutron capture cross-section measurements, and recent advances in evaluation techniques have stimulated a revision of the International Reactor Dosimetry and Fusion File evaluation. The basic characteristics of the new evaluation are as follows: The evaluated thermal cross section is about 2.5 % higher than the value recommended by Mughabghab. In the resolved resonance region, the evaluated cross section is parameterized by the Reich-Moore formula without a background contribution. In the high-energy region, the evaluated values had been calculated using a PADE2 code on the basis of the experimental data and the results of theoretical model calculations. The new evaluation contains complete cross-section covariance information and provides a better agreement with both the differential and integral experimental cross-section data.
Methodology Qualification for the 3D RAPTOR-M3G Discrete Ordinates Transport Code on Traditional Beltline
Authors: Chen Jianwei , Fischer Greg A. , Kim Byoung Chul
Published: December 2018

Regulatory Guide (RG) 1.190 provides the basis for the U.S. Nuclear Regulatory Committee (NRC) to review any nuclear reactor vessel fluence calculation work that has been submitted to the committee. RG 1.190 intends to ensure the accuracy and reliability of the neutron fluence determination required by general design criteria related to the reactor coolant pressure boundary. RG 1.190 describes methods and assumptions acceptable to the NRC staff for determining the pressure vessel neutron fluence. RAPTOR-M3G (which stands for rapid parallel transport of radiation—multiple three-dimensional geometries) is a three-dimensional parallel discrete ordinates transport code that has been developed by Westinghouse Electric Company LLC Radiation Engineering Analysis group that can be used for commercial reactor vessel fluence production work. However, in order for RAPTOR-M3G to be accepted by NRC to perform fluence calculation for a pressurized water reactor fleet, a generic methodology qualification and uncertainty estimates must be performed. The methods qualification consists of three parts: (1) the analytical uncertainty analysis, (2) the comparison with benchmarks and operating reactor measurements, and (3) the estimate of uncertainty in the calculated fluence. This paper describes how RAPTOR-M3G 3D parallel discrete ordinates code was qualified per RG 1.190.
Results of a New Evaluation of the Neutron Standards
Authors: Carlson Allan D. , Pronyaev Vladimir G. , Capote Roberto , Hale Gerald M. , Duran Ignacio , Hambsch Franz-Josef , Kunieda Satoshi , Mannhart Wolf , Marcinkevicius Benjaminas , Nelson Ronald O. , Noguere Gilles , Schillebeeckx Peter , Simakov Stanislav , Tao Xi , Trkov Andrej , Wallner Anton , Wang Wenming
Published: December 2018

An international effort has produced evaluations of the neutron data standards. Evaluations were obtained for the cross section standards: the H(n,n), 6Li(n,t), 10B(n,αγ), 10B(n,α), natC(n,n), Au(n,γ), 235U(n,f), and 238U(n,f) reactions. Also in the evaluation process, the 238U(n,γ) and 239Pu(n,f) nonstandard cross sections were evaluated. Many of these are dosimetry cross sections. Evaluations were also obtained for data that are not traditional standards: Maxwellian spectrum averaged cross section for the Au(n,γ) cross section at 30 keV, reference cross sections for prompt γ-ray production in fast neutron-induced reactions, reference cross sections for very high-energy fission cross sections, the 252Cf spontaneous fission neutron spectrum and the 235U thermal fission neutron spectrum, and the thermal constants. The data and covariances were obtained directly from this evaluation procedure as is required by the dosimetry community.
Using Total Monte Carlo to Calculate the Full Covariance Matrix of a Neutron Spectrum
Authors: Asquith Nicola L. , van der Marck Steven C.
Published: December 2018

A new scheme is proposed for calculating the covariance matrix of an a priori neutron flux spectrum using the Total Monte Carlo method. This covariance matrix can be used to improve the adjustment of calculated spectra to dosimetry measurements in a more physically realistic way. We have taken an example experiment performed at the High Flux Reactor to successfully demonstrate the application of this covariance matrix to spectrum adjustment procedures using a modified J1 unfolding algorithm.
The Effects of Radiation Hardening on the Reusability of CaF2:Mn TLDs
Authors: Daniel Joshua D. , Henneke Dale , Vehar David W.
Published: December 2018

Manganese-doped calcium fluoride thermoluminescent dosimeters (TLDs) are used for characterizing absorbed dose at many facilities around the world. Due to their relatively high cost, reusability of the TLDs is desired. However, due to radiation damage mechanisms within the TLDs, their accuracy diminishes as their total absorbed dose increases, which restricts reusability. After approximately 20,000 rads(Si) (200 Gy) the batch percent standard deviation increases by up to 4 %, making virgin TLDs significantly more accurate for precision radiation dosimetry. This study examines the effects of radiation hardening and thermal annealing procedures on reusability and batch uncertainty. The primary method will be irradiating virgin TLD chips to 100 to 100,000 Rad(Si) (1 to 1,000 Gy) and then comparing them with TLDs exposed to the same levels that had been previously irradiated to 100,000 rad(Si) (1,000 Gy). The intent is to reduce the amount of batch uncertainty introduced by high levels of radiation dose. The radiation hardening did not have a conclusive effect on reusability. However, the variation introduced at higher dose levels seemed to be less than previous work, so hardening and batch recalibration could be an option for repeated uses. Increased sensitivity at lower doses was also seen after hardening. This increase was also explored in more detail. More research will be needed to draw definitive conclusions.
Shielding and Activation Studies for the MYRRHA Research Reactor
Authors: Müller Stefan E. , Ferrari Anna , Konheiser Jörg
Published: December 2018

The planned Multipurpose Hybrid Research Reactor for High-Tech Applications (or MYRRHA) research reactor in Mol, Belgium, aims to demonstrate efficient transmutation of high-level waste and associated accelerator-driven systems technology. The system is based on a lead-bismuth eutectic cooled reactor, working both in critical and in subcritical operation modes. The neutrons needed to sustain fission in the subcritical mode are produced via spallation processes by a 600-MeV less than or equal to 4 mA proton beam, which is provided by a linear accelerator and hits a lead-bismuth eutectic spallation target located inside the reactor core. In order to assess the main shielding problems, a method based on the combined use of the two Monte Carlo codes MCNP and FLUKA was developed, with the goal to perform detailed analyses of both the radiation fields due to the system in operation and the coupled residual radiation due to the activated materials. As a result, neutron and photon fluences as well as prompt and residual ambient dose equivalent rates were evaluated. In addition, an activation database for many of the structural materials was built.
Estimation of Void Swelling in VVER-1000 Baffle Using Benchmark in LR-0 Reactor
Authors: Harutyunyan Davit , Mirzov Ihor , Košt´ál Michal , Schulc Martin , Klupák Vít
Published: December 2018

Reactor pressure vessel internals have a multipurpose task that is mainly to ensure optimal coolant flow, to form and support the active core, and to shield, guide, and support the in-core instrumentation. The VVER-1000 reactor internal components are in an environment with high radiation doses, boric (H3BO3) acid dissolved in water, high temperatures, and gamma heating. These effects, together with the high moderator flow rate, form strongly inhomogeneous temperature fields in vessel internal components and induced internal stresses. In the case of the VVER-1000 reactor baffle, the main potential limiting factor for prolongation of the reactor operational lifetime is a void swelling of the Russian-type titanium stabilized stainless 08Cr18Ni10Ti steel used to construct the baffle surrounding the active core. This paper presents a VVER-1000 mock-up model validation for the thermal neutron and gamma fluence in the region of the baffle and a precise gamma heating as well as a displacement-per-atom estimation in a one-sixth section of the reactor baffle. Obtained results on the mock-up are scaled to the VVER-1000 nominal power and used in ABAQUS code for void swelling estimation.
Tritium Management in FLiBe-cooled Reactors: Assessing All Pathways of Tritium Production in a Detailed Model
Authors: Flaspoehler Timothy , Petrovic Bojan
Published: December 2018

Fluoride-salt-cooled high-temperature reactor (FHR) designs use FLiBe salt as a coolant, and thus generate a significant amount of tritium, which becomes an operational challenge in terms of radioactive protection. In the design of a tritium management program, it is important to accurately estimate the spatial and temporal tritium production rate. This is the scope of this work, achieved by three-dimensional neutronics simulations throughout all areas of an FHR, including the FLiBe coolant, graphite moderator, graphite reflector, and fuel planks with embedded tristructural-isotropic (TRISO) particles. Note that the subsequent tritium transport within the system, and the methods for its removal are not addressed. The lithium isotope 6Li in the coolant is expected to be the main tritium precursor and thus the primary focus. Unlike the TRISO fuel particles that contain tritium by design, the FLiBe coolant directly interacts with the primary heat exchangers, which provides a large avenue for tritium to escape the primary loop. This work seeks to ensure that not only are the models accurate but also the data libraries and physics involved with calculating tritium production. A computational methodology using the Monte Carlo N-Particle MCNP6.1 and Standardized Computer Analyses for Licensing Evaluation SCALE6.2 code packages has been developed and is presented in the paper. Impact of the fuel design, as well as modeling approximations have been examined. Initial tritium production rates have a strong dependence on fuel enrichment (varying between roughly 13,700 and 9,300 Ci/day), while equilibrium rates converge to the same levels of roughly 3,800 Ci/day. For the reference case, it was found that 21.5 MCi of tritium are produced by the end of a 100-year reactor lifetime.
Cross-Modal Competition: The Default Computation for Multisensory Processing
Authors: Yu Liping , Cuppini Cristiano , Xu Jinghong , Rowland Benjamin A. , Stein Barry E.
Published: December 2018

Mature multisensory superior colliculus (SC) neurons integrate information across the senses to enhance their responses to spatiotemporally congruent cross-modal stimuli. The development of this neurotypic feature of SC neurons requires experience with cross-modal cues. In the absence of such experience the response of an SC neuron to congruent cross-modal cues is no more robust than its response to the most effective component cue. This “default” or “naive” state is believed to be one in which cross-modal signals do not interact. The present results challenge this characterization by identifying interactions between visual-auditory signals in male and female cats reared without visual-auditory experience. By manipulating the relative effectiveness of the visual and auditory cross-modal cues that were presented to each of these naive neurons, an active competition between cross-modal signals was revealed. Although contrary to current expectations, this result is explained by a neuro-computational model in which the default interaction is mutual inhibition. These findings suggest that multisensory neurons at all maturational stages are capable of some form of multisensory integration, and use experience with cross-modal stimuli to transition from their initial state of competition to their mature state of cooperation. By doing so, they develop the ability to enhance the physiological salience of cross-modal events thereby increasing their impact on the sensorimotor circuitry of the SC, and the likelihood that biologically significant events will elicit SC-mediated overt behaviors.

SIGNIFICANCE STATEMENTThe present results demonstrate that the default mode of multisensory processing in the superior colliculus is competition, not non-integration as previously characterized. A neuro-computational model explains how these competitive dynamics can be implemented via mutual inhibition, and how this default mode is superseded by the emergence of cooperative interactions during development.
Linking knowledge to action in ocean ecosystem management: The Ocean Modeling Forum
Authors: Francis Tessa B. , Levin Phillip S. , Punt Andre E. , Kaplan Isaac C. , Varney Anna , Norman Karma
Published: December 2018

The sustainable use of global marine resources depends upon science-based decision processes and systems. Informing decisions with science is challenging for many reasons, including the nature of science and science-based institutions. The complexity of ecosystem-based management often requires the use of models, and model-based advice can be especially difficult to convert into policies or decisions. Here, we suggest five characteristics of model-based information and advice for successfully informing ocean management decision-making, based on the Ocean Modeling Forum framework. Illustrated by examples from two fisheries case studies, Pacific sardines Sardinops sagax and Pacific herring Clupea pallasii, we argue that actionable model-based output should be aspirational, applicable, parsimonious, co-produced, and amplifying.
Un capítulo poco conocido de la historia de la patata en la región parisina durante el siglo XIX
Authors: Herment Laurent
Published: December 2018

Las patatas constituyeron una de las plantas americanas que permitiern a los países europeos enfrentar su crecimiento demográfico entre finales del Antiguo Régimen y el remate del siglo XIX. Al contrario de lo sucedido en los países de la Europa septentrional, Galicia y el norte de Portugal, y con muy pocas excepciones regionales, en Francia, la patata no jugó un papel relevante en la alimentación de la población. Pese a ello, en algunas regiones, como por ejemplo en la cuenca de Paris, el Bassin Parisien, fue un cultivo muy importante. En esta zona, su rendimiento se multiplicó por diez entre finales del Primer Imperio y la década de 1860. A pesar de ello, no formaba parte de la dieta de la población rural, sino que era, más bien, un cultivo industrial utilizado por la industria del fécula para producir, entre otras cosas, glucosa y alcohol. Más allá del caso de la mencionada cuenca de Paris, la hipótesis de este trabajo es que la patata solo habría llegado a integrarse en la dieta de la población francesa si el precio del combustible (madera, carbón o turba) y el de la grasa animal o vegetal hubiesen sido bajos.
Optical solitons and modulation instability analysis to the quadratic-cubic nonlinear Schrödinger equation
Authors: Inc Mustafa , Aliyu Aliyu Isa Isa , Yusuf Abdullahi , Baleanu Dumitru
Published: December 2018

This paper obtains the dark, bright, dark-bright, dark-singular optical and singular soliton solutions to the nonlinear Schrödinger equation with quadratic-cubic nonlinearity (QC-NLSE), which describes the propagation of solitons through optical fibers. The adopted integration scheme is the sine-Gordon expansion method (SGEM). Further more, the modulation instability analysis (MI) of the equation is studied based on the standard linear-stability analysis, and the MI gain spectrum is got. Physical interpretations of the acquired results are demonstrated. It is hoped that the results reported in this paper can enrich the nonlinear dynamical behaviors of the PNSE.
Integral estimates of the solutions of fractional-like equations of perturbed motion
Authors: Martynyuk Anatoliy , Stamov Gani , Stamova Ivanka
Published: December 2018

In this paper, the results of the analysis of nonlinear systems with fractional-like derivatives of the state vector are presented. Using the method of integral inequalities, some estimates of the solutions are obtained, and criteria for Heyers–Ulam–Rassias stability of a fractional-like scalar equation are established.
Promotion of a Healthy Lifestyle among Students (a Sociological Analysis)
Authors: Zhiratkova Zhanna V. , Petrova Tatiana E. , Leontyeva Alesya V.
Published: December 2018

Introduction. The issue of public health is still relevant, as not only is it an individual value, but also a social one: an unhealthy population cannot be a reliable support for the state. This is especially true of young people, who are a key indicator of the well-being of the society and the country as a whole. The goal of the paper is to study the opinions of students about a healthy lifestyle and its promotion through tourism, prevention of addictions and negative impacts of various factors.

Materials and Methods. In the course of the research, a set of methods was applied: analytical and synthetic study of scientific and methodological literature, logical methods for analyzing concepts, questionnaire surveys, expert evaluation, etc. The study also used quota sampling. Percentage distribution and ranking were used to process the empirical data.

Results. The conducted experiment has revealed that most students enjoy good health and show optimism, they have a tolerant attitude towards people consuming alcohol or drugs. The study has proved that health and well-being of young people depend on the socio-psychological microclimate in students’ groups and dormitories, as well as on the friendship and solidarity of students themselves.

Discussion and Conclusion. Only promoting a fashion for a healthy lifestyle one can protect students from negative consequences during the transition from the youth to adulthood. The materials obtained can become the basis for monitoring these processes in educational organizations and set new vectors for students’ better health, for improving the teamwork of teachers and mentors.
Field-Effect Mobility and Morphology Study in Amorphous Films of Symmetric and Unsymmetrical Spiro-Linked Compounds
Authors: Saragi Tobat P. I. , Pudzich Robert , Fuhrmann Thomas , Salbeck Josef
Published: December 2018

We have investigated the field-effect mobility of three kinds of low molecular weight spirolinked compounds, namely 2,2',7,7'-tetrakis (diphenylamino)-9,9'-spirobifluorene (spiro-TAD), 2,2',7,7'-tetrakis(biphenyl-4-yl)-9,9'-spirobifluorene (spiro-6φ) and 2,7-bis-(N,N-diphenylamino)- 2',7'-bis-(biphenyl-4-yl)-9,9'-spirobifluorene (spiro-X2). The field-effect mobilities of these materials in the saturation region are 8 x 10-4 cm2V-1s-1, 5 x 10-5 cm2V-1s-1 and 4 x 10-4 cm2V-1s-1 respectively. The atomic force microscopy images show that films prepared from these materials are amorphous with a very smooth surface and the limited field-effect mobility is due to the intrinsic behaviour of amorphous materials.
Anomalous Temperature Dependence of Solvent-Enhanced Dye Diffusion In Polymer Films
Authors: Graves-Abe T. , Pschenitzka F. , Sturm J.C.
Published: December 2018

One promising method to pattern full color polymer Organic Light-Emitting Diode (OLED) displays is to print dye from a pre-patterned organic film onto a spin-cast polymer and then diffuse the dye into the film at room temperature in a solvent vapor environment. This method utilizes the well-known tendency for a polymer film to absorb solvent vapor, which depresses the glass transition temperature of the polymer and dramatically increases diffusion the dye. In this work, we have studied the temperature dependence of this process. The dye coumarin 6 (C6) was transferred onto films consisting of 2-(4-biphenylyl)-5-(4-tert-butylphenyl)- 1,3,4-oxadiazole (PBD) mixed with the polymer poly(9-vinylcarbazole) (PVK). Samples were then placed on a heated stage in a chamber and exposed to acetone vapor to diffuse the C6 into the polymer film. The profile of the diffused dye was determined by depthdependent photoluminescence measurements and Secondary Ion Mass Spectroscopy. We observed that the amount of diffused dye decreased at higher temperatures, in contrast to conventional thermally-driven diffusion. The results are understood by noting that the decrease in the polymer glass-transition temperature and the corresponding rapid increase in dye diffusivity depend on the quantity of solvent absorbed by the polymer, which decreases as the temperature of the polymer is raised.
Dopant Pairing in a Molecular Semiconductor
Authors: Branz Howard M. , Gregg Brian A.
Published: December 2018

Recent doping experiments in n-type perylene diimide (PPEEB) semiconducting thin films showed an unexpected quadratic dependence of electrical conductivity upon dopant molecule concentration. We propose that singly-ionized dopant pairs outnumber ionized unpaired dopants and dominate conductivity. Random association into dopant pairs during spin coating then explains the quadratic dependence. Classical calculations confirm that dopant pairing reduces the binding energy of the easiest-to-ionize electron. Our model agrees with the measured conductivity activation energy and magnitude, assuming typical electron mobility in the crystal. The random distribution of dopants implies their distribution cannot equilibrate during the spincoating process.
The influence of the microstructure upon the photovoltaic performance of MDMOPPV: PCBM bulk hetero-junction organic solar cells
Authors: Martens T. , D'Haen J. , Munters T. , Goris L. , Beelen Z. , Manca J. , D'Olieslaeger M. , Vanderzande D. , Schepper L. De , Andriessen R.
Published: December 2018

In this paper, a clear view on the bulk microstructure of MDMO-PPV:PCBM blends as used in bulk hetero-junction organic solar cells is obtained by means of TEM (Transmission Electron Microscopy). Using TEM, 3-dimensional information is acquired on phase separated regions, formed during casting. Particle statistics illustrate quantitatively that a.o. drying conditions and choice of solvent dramatically influence the blend structure. More information about the lateral blend structure and distribution is obtained in cross-sectional view. Since blend morphology is strongly related to photovoltaic performance, TEM can be a powerful tool for understanding today's photovoltaic performances and screening new sets of materials.
Revitalização da Industria de Defesa no Brasil: Desafios e Oportunidades para o Arranjo Produtivo em São Bernardo do Campo
Authors: Dos Santos Isabel Cristina , Nunes Vinicius Domingues
Published: December 2018

Esta pesquisa tem como objetivo identificar os desafios à revitalização da indústria de defesa nacional a partir da implantação do arranjo produtivo local de defesa de São Bernardo do Campo. Para tanto, optou-se por uma abordagem qualitativa, com caráter exploratório-descritivo. A coleta de dados baseou-se em: análise histórica e documental, o que permitiu descrever a constituição do setor e identificar o crescimento e declínio do setor, bem como, objetivos e estratégias definidas para o arranjo produtivo de Defesa. Entrevistas estruturadas realizadas junto a uma amostra de sujeitos, atuantes no setor, complementam a coleta de dados e apoiam a análise sistematizada dos aspectos inerentes aos cenários, no setor, alguns dos quais derivados da experiência empírica dos entrevistados. Os resultados obtidos apontam a necessidade de estabelecer parceria com o Governo que deverá lançar incentivos econômicos, tecnológicos e institucionais para que a revitalização da indústria, como uma alternativa econômica e social relevante para o Grande ABC, possa lograr sucesso. Portanto, conclui-se que a definição dos desafios da indústria de defesa e do APL de São Bernardo do Campo estão relacionados ao apoio ou à ausência dele por parte do governo.