2,679 results match your criteria neutron total

Radiobiological impact of Gadolinium neutron capture from proton therapy and alternative neutron sources using Topas-nBio.

Med Phys 2021 May 7. Epub 2021 May 7.

Department of Physics, Faculty of Science, Ryerson University, 350 Victoria St, Toronto, Ontario, Canada, M5B 2K3.

Purpose: A multi-scale investigation of the biological properties of gadolinium neutron capture (GdNC) therapy is conducted using Monte Carlo (MC) simulation code. The simulation results are used to quantify the amount of gadolinium dose enhancement produced from different neutron sources. The amount of dose enhancement is quantified as a result of the secondary neutron production from proton therapy scaled by measured data. Read More

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New highly radioactive particles derived from Fukushima Daiichi Reactor Unit 1: Properties and environmental impacts.

Sci Total Environ 2021 Jun 5;773:145639. Epub 2021 Feb 5.

Department of Chemistry, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan. Electronic address:

A contaminated zone elongated toward Futaba Town, north-northwest of the Fukushima Daiichi Nuclear Power Plant (FDNPP), contains highly radioactive particles released from reactor Unit 1. There are uncertainties associated with the physio-chemical properties and environmental impacts of these particles. In this study, 31 radioactive particles were isolated from surface soils collected 3. Read More

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Analysis of the soil to food crops transfer factor and risk assessment of multi-elements at the suburban area of Ho Chi Minh city, Vietnam using instrumental neutron activation analysis (INAA).

J Environ Manage 2021 Apr 28;291:112637. Epub 2021 Apr 28.

Nuclear Technique Laboratory, University of Science, Ho Chi Minh City, Viet Nam; Faculty of Physics and Engineering Physics, University of Science, Ho Chi Minh City, Viet Nam; Vietnam National University Ho Chi Minh City, Viet Nam.

The contamination of heavy metals in agricultural ecosystem is one of the most important problems in developing countries as Vietnam. In this study, we investigated the multi-element concentrations in soil, vegetables, soil-to-plant transfer factors and target hazard quotient (THQ) due to the consumption of heavy metals in Ho Chi Minh City, Vietnam. In general, the element concentrations in soil and plants were similar to different studies in the world and in the range of allowable values provided by WHO and the Ministry of Health of Vietnam. Read More

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Chronic Low Dose Neutron Exposure Results in Altered Neurotransmission Properties of the Hippocampus-Prefrontal Cortex Axis in Both Mice and Rats.

Int J Mol Sci 2021 Apr 1;22(7). Epub 2021 Apr 1.

Department of Radiation Oncology, Eastern Virginia Medical School, Norfolk, VA 23507, USA.

The proposed deep space exploration to the moon and later to Mars will result in astronauts receiving significant chronic exposures to space radiation (SR). SR exposure results in multiple neurocognitive impairments. Recently, our cross-species (mouse/rat) studies reported impaired associative memory formation in both species following a chronic 6-month low dose exposure to a mixed field of neutrons (1 mGy/day for a total dose pf 18 cGy). Read More

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Thermal neutron cross sections of amino acids from average contributions of functional groups.

J Phys Condens Matter 2021 Apr 27. Epub 2021 Apr 27.

Universita di Roma 'Tor Vergata', via della Ricerca Scientifica 1, I-00133 Roma, Roma, 00133, ITALY.

The experimental thermal neutron cross sections of the twenty proteinogenic amino acids have been measured over the incident-neutron energy range spanning from 1 meV to 10 keV and data have been interpreted using the multi-phonon expansion based on first-principles calculations. The scattering cross section, dominated by the incoherent inelastic contribution from the hydrogen atoms, can be rationalised in terms of the average contributions of different functional groups, thus neglecting their correlation. These results can be used for modelling the total neutron cross sections of complex organic systems like proteins, muscles, or human tissues from a limited number of starting input functions. Read More

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Intermediate scattering functions of a rigid body monoclonal antibody protein in solution studied by dissipative particle dynamic simulation.

Struct Dyn 2021 Mar 8;8(2):024102. Epub 2021 Apr 8.

NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA.

In the past decade, there was increased research interest in studying internal motions of flexible proteins in solution using Neutron Spin Echo (NSE) as NSE can simultaneously probe the dynamics at the length and time scales comparable to protein domain motions. However, the collective intermediate scattering function (ISF) measured by NSE has the contributions from translational, rotational, and internal motions, which are rather complicated to be separated. Widely used NSE theories to interpret experimental data usually assume that the translational and rotational motions of a rigid particle are decoupled and independent to each other. Read More

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Small Molecule Responses to Sequential Irradiation with Neutrons and Photons for Biodosimetry Applications: An Initial Assessment.

Radiat Res 2021 Apr 15. Epub 2021 Apr 15.

Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC.

Mass casualty exposure scenarios from an improvised nuclear device are expected to be far more complex than simple photons. Based on the proximity to the explosion and potential shielding, a mixed field of neutrons and photons comprised of up to approximately 30% neutrons of the total dose is anticipated. This presents significant challenges for biodosimetry and for short-term and long-term medical treatment of exposed populations. Read More

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Illustrated formalisms for total scattering data: a guide for new practitioners.

J Appl Crystallogr 2021 Feb 1;54(Pt 1):317-332. Epub 2021 Feb 1.

Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA.

The total scattering method is the simultaneous study of both the real- and reciprocal-space representations of diffraction data. While conventional Bragg-scattering analysis (employing methods such as Rietveld refinement) provides insight into the average structure of the material, pair distribution function (PDF) analysis allows for a more focused study of the local atomic arrangement of a material. Generically speaking, a PDF is generated by Fourier transforming the total measured reciprocal-space diffraction data (Bragg and diffuse) into a real-space representation. Read More

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February 2021

Magnetic Ordering in the Ising Antiferromagnetic Pyrochlore NdScNbO.

J Phys Condens Matter 2021 Apr 7. Epub 2021 Apr 7.

University of Winnipeg, 599 Portage Ave, Winnipeg, Manitoba, R3B 2E9, CANADA.

The question of structural disorder and its effects on magnetism is relevant to a number of spin liquid candidate materials. Although commonly thought of as a route to spin glass behaviour, here we describe a system in which the structural disorder results in long-range antiferromagnetic order due to local symmetry breaking. NdScNbOis shown to have a dispersionless gapped excitation observed in other neodymium pyrochlores below T=0. Read More

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Mixed hierarchical local structure in a disordered metal-organic framework.

Nat Commun 2021 Apr 6;12(1):2062. Epub 2021 Apr 6.

Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, UK.

Amorphous metal-organic frameworks (MOFs) are an emerging class of materials. However, their structural characterisation represents a significant challenge. Fe-BTC, and the commercial equivalent Basolite® F300, are MOFs with incredibly diverse catalytic ability, yet their disordered structures remain poorly understood. Read More

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Conformal Radiotherapy in Patients with Cardiovascular Implantable Electronic Devices: Proposed Practical Implementation of the TG-203 Risk-Stratified Interrogation Schedule.

Pract Radiat Oncol 2021 Apr 3. Epub 2021 Apr 3.

Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD. Electronic address:

Introduction: Radiotherapy (RT) in patients with cardiac implantable electronic devices (CIED) carries a risk of device malfunction from radiation exposure. We sought to evaluate the incidence of CIED malfunction in a cohort of patients treated with modern RT techniques.

Material And Methods: A retrospective analysis of 193 CIED patients treated with RT between 2000 and 2018 was conducted. Read More

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Effect of Ligand Polarity on the Internal Dipoles and Ferroelectric Distortion in BaTiO Nanocubes.

Chemistry 2021 Apr 5. Epub 2021 Apr 5.

Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.

Surface adsorbates and surrounding matrix species have been demonstrated to affect the properties of nanoscale ferroelectrics and nanoscale ferroelectric composites; potentially counteracting performance losses that can occur in small particle sizes. In this work, the effects of nonpolar oleic acid (OA) and polar tetrafluoroborate (BF ) ligand capping on the surface of various sizes of BaTiO nanocubes have been investigated with combined neutron diffraction and neutron pair distribution function (PDF), density functional theory (DFT), and ab initio molecular dynamics (AIMD) methods. The low real space PDF region provides an unobstructed view of rhombohedral (split short and long) Ti-O distances in BaTiO nanocubes, mimicking the well-established order-disorder local structure found in bulk BaTiO . Read More

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Biophysical analysis of the plant-specific GIPC sphingolipids reveals multiple modes of membrane regulation.

J Biol Chem 2021 Mar 27:100602. Epub 2021 Mar 27.

Laboratoire de Biogènese Membranaire, UMR 5200, CNRS, Université de Bordeaux, 71 Avenue Edouard Bourlaux, 33883 Villenave d'Ornon Cedex, France. Electronic address:

The plant plasma membrane (PM) is an essential barrier between the cell and the external environment, controlling signal perception and transmission. It consists of an asymmetrical lipid bilayer made up of three different lipid classes: sphingolipids, sterols and phospholipids. The Glycosyl Inositol Phosphoryl Ceramides (GIPCs), representing up to 40% of total sphingolipids, are assumed to be almost exclusively in the outer leaflet of the PM. Read More

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Virtual estimation of effective dose in neutron fields.

J Radiol Prot 2021 Mar 30. Epub 2021 Mar 30.

Studiecentrum voor Kernenergie, Mol, BELGIUM.

The PODIUM project aims to provide real-time assessments of occupationally exposed workers by tracking their motion and combining this with a simulation of the radiation field. The present work describes the approach that would be taken in mixed neutron-gamma fields, and details the methods for generating and applying an effective dose rate map; the required fluence to effective dose conversion coefficients at intercardinal angles are also presented. A proof-of-concept of the approach is demonstrated using a simple simulated workplace field within a calibration laboratory, with corroborative comparisons made against survey instrument measurements generally confirming good agreement. Read More

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Unusual Maximum in the Adsorption of Aqueous Surfactant Mixtures: Neutron Reflectometry of Mixtures of Zwitterionic and Ionic Surfactants at the Silica-Aqueous Interface.

Langmuir 2021 Apr 28;37(13):3939-3949. Epub 2021 Mar 28.

Rutherford-Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX, U.K.

The adsorption of two zwitterionic surfactants, dodecyldimethylammonium propanesulfonate (CPS) and dodecyldimethylammonium carboxybetaine (CCB), and of their mixtures with the cationic dodecyltrimethylammonium bromide (CTAB) and the anionic sodium dodecylsulfate (SDS) at the silica-water interface has been studied by neutron reflection (NR). The total adsorption, the composition of the adsorbed layer, and some structural information have been obtained over a range of concentrations from below the critical micelle concentration (CMC) to about 30× the mixed CMC. The adsorption behavior has been considered in relation to the previously measured micellar equilibrium of these mixtures in their bulk solutions and their adsorption at the air-water interface. Read More

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Whole body potassium as a biomarker for potassium uptake using a mouse model.

Sci Rep 2021 Mar 18;11(1):6385. Epub 2021 Mar 18.

School of Health Sciences, Purdue University, West Lafayette, 47906, USA.

Potassium is known for its effect on modifiable chronic diseases like hypertension, cardiac disease, diabetes (type-2), and bone health. In this study, a new method, neutron generator based neutron activation analysis (NAA), was utilized to measure potassium (K) in mouse carcasses. A DD110 neutron generator based NAA assembly was used for irradiation. Read More

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Effects of neutron radiation on Nrf2-regulated antioxidant defense systems in rat lens.

Exp Ther Med 2021 Apr 8;21(4):334. Epub 2021 Feb 8.

Department of Ophthalmology, The Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, Jiangsu 210029, P.R. China.

Accumulating evidence suggests that ionizing radiation (IR)-induced cataract may be associated with oxidative stress. Nuclear factor erythroid 2-related factor 2 (Nrf2) serves as a master regulator of the antioxidant defense system against oxidative stress. The present study aimed to investigate the effects of different doses of neutron radiation on the Nrf2-reegulated antioxidant defense system in rat lens and assess the status of oxidative stress. Read More

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Pressure-Dependent Structure of Methanol-Water Mixtures up to 1.2 GPa: Neutron Diffraction Experiments and Molecular Dynamics Simulations.

Molecules 2021 Feb 25;26(5). Epub 2021 Feb 25.

Wigner Research Centre for Physics, Konkoly Thege út 29-33, H-1121 Budapest, Hungary.

Total scattering structure factors of per-deuterated methanol and heavy water, CDOD and DO, have been determined across the entire composition range as a function of pressure up to 1.2 GPa, by neutron diffraction. The largest variations due to increasing pressure were observed below a scattering variable value of 5 Å, mostly as shifts in terms of the positions of the first and second maxima. Read More

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February 2021

Dosimetric effects of composition, location and size of tissue heterogeneities on Cf neutron brachytherapy.

Appl Radiat Isot 2021 May 14;171:109639. Epub 2021 Feb 14.

Biomedical Engineering and Medical Physics Department, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Electronic address:

The purpose of this study is to evaluate the effect of tissue heterogeneities on dose distribution in Californium-252(Cf) neutron brachytherapy. The effect of location and size of heterogeneity on dose distribution was also evaluated. Neutron and photon dose rate distributions were determined in a water phantom in presence of air, lung, soft tissue and bone heterogeneities using MCNPX code. Read More

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Galactic cosmic ray effects on iron and nickel isotopes in iron meteorites.

Meteorit Planet Sci 2020 Dec 11;55(12):2758-2771. Epub 2020 Feb 11.

Institute for Geochemistry and Petrology ETH Zürich Clausiusstrasse 25 8092 Zürich Switzerland.

We present model calculations for cosmogenic production rates in order to quantify the potential effects of spallation and neutron capture reactions on Fe and Ni isotopes in iron meteorites. We aim to determine whether the magnitude of any cosmogenic effects on the isotopic ratios of Fe and/or Ni may hinder the search for nucleosynthetic variations in these elements or in the application of the Fe-Ni chronometer. The model shows that neutron capture reactions are the dominant source of shifts in Fe and Ni isotopic ratios and that spallation reactions are mostly negligible. Read More

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December 2020

Deep Learning Accelerated Determination of Hydride Locations in Metal Nanoclusters.

Angew Chem Int Ed Engl 2021 Mar 4. Epub 2021 Mar 4.

Department of Chemistry, University of California, Riverside, CA, 92521, USA.

Although the coordinates of the metal atoms can be accurately determined by X-ray crystallography, locations of hydrides in metal nanoclusters are challenging to determine. In principle, neutron crystallography can be employed to pinpoint the hydride positions, but it requires a large crystal and a neutron source, which prevents its routine use. Here, we present a deep-learning approach that can accelerate determination of hydride locations in single-crystal X-ray structure of metal nanoclusters of different sizes. Read More

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Determination of scale deposition in a flare line by neutron back-diffusion.

Appl Radiat Isot 2021 Feb 21;168:109424. Epub 2020 Oct 21.

Nuclear Engineering Department, Faculty of Engineering, King Abdulaziz University, P.O. Box 80204, Jeddah, 21589, Saudi Arabia.

Flares are used in the oil industry and other industries to dispose of waste gasses by burning. Damaged or blocked flares can lead to incomplete combustion and the release of contaminating gasses into the atmosphere. In this study, the neutron back-diffusion technique was used to measure the scale inside a flare stack. Read More

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February 2021

Nonlinear excitations of magnetosonic solitary waves and their chaotic behavior in spin-polarized degenerate quantum magnetoplasma.

Chaos 2021 Feb;31(2):023133

Department of Physics, University of Peshawar, Peshawar 25000, Pakistan.

The quantum hydrodynamic model is used to study the nonlinear propagation of small amplitude magnetosonic solitons and their chaotic motions in quantum plasma with degenerate inertialess spin-up electrons, spin-down electrons, and classical inertial ions. Spin effects are considered via spin pressure and macroscopic spin magnetization current, whereas the exchange effects are considered via adiabatic local density approximation. By applying the reductive perturbation method, the Korteweg-de Vries type equation is derived for small amplitude magnetosonic solitary waves. Read More

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February 2021

Neutron total scattering investigation on the dissolution mechanism of trehalose in NaOH/urea aqueous solution.

Struct Dyn 2021 Jan 10;8(1):014901. Epub 2021 Feb 10.

Institute for Advanced Study, Shenzhen University, Shenzhen 508060, China.

Trehalose is chosen as a model molecule to investigate the dissolution mechanism of cellulose in NaOH/urea aqueous solution. The combination of neutron total scattering and empirical potential structure refinement yields the most probable all-atom positions in the complex fluid and reveals the cooperative dynamic effects of NaOH, urea, and water molecules in the dissolution process. NaOH directly interacts with glucose rings by breaking the inter- and intra-molecular hydrogen bonding. Read More

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January 2021

Material properties particularly suited to be measured with helium scattering: selected examples from 2D materials, van der Waals heterostructures, glassy materials, catalytic substrates, topological insulators and superconducting radio frequency materials.

Phys Chem Chem Phys 2021 Apr 24;23(13):7653-7672. Epub 2021 Feb 24.

Department of Physics and Technology, University of Bergen, Allegaten 55, 5007 Bergen, Norway.

Helium Atom Scattering (HAS) and Helium Spin-Echo scattering (HeSE), together helium scattering, are well established, but non-commercial surface science techniques. They are characterised by the beam inertness and very low beam energy (<0.1 eV) which allows essentially all materials and adsorbates, including fragile and/or insulating materials and light adsorbates such as hydrogen to be investigated on the atomic scale. Read More

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A comprehensive Monte Carlo study of out-of-field secondary neutron spectra in a scanned-beam proton therapy gantry room.

Z Med Phys 2021 Feb 20. Epub 2021 Feb 20.

LMU Munich, Faculty of Physics, Department of Medical Physics, Am Coulombwall 1, 85748 Garching bei München, Germany.

Purpose: To simulate secondary neutron radiation fields that had been measured at different relative positions during phantom irradiation inside a scanning proton therapy gantry treatment room. Further, to identify origin, energy distribution, and angular emission of the secondary neutrons as a function of proton beam energy.

Methods: The FLUKA Monte Carlo code was used to model the relevant parts of the treatment room in a scanned pencil beam proton therapy gantry including shielding walls, floor, major metallic gantry-components, patient table, and a homogeneous PMMA target. Read More

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February 2021

Gamma / neutron radiation shielding, structural and physical characteristics of iron slag nanopowder.

Appl Radiat Isot 2021 Apr 2;170:109606. Epub 2021 Feb 2.

Physics Department, College of Science, Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh, 11652, Saudi Arabia. Electronic address:

The current study explores the effectiveness of an iron slag nanopowder (ISNP), which prepared from local iron steel industry, against gamma/neutron shielding. The structural and physical characteristics were experimentally determined. The crystal structure, morphology and elemental composition of the ISNP were studied using X-ray diffraction, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX). Read More

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Fatigue Reliability Analysis Method of Reactor Structure Considering Cumulative Effect of Irradiation.

Materials (Basel) 2021 Feb 8;14(4). Epub 2021 Feb 8.

Faculty of Mechanical Engineering and Aeronautics, Rzeszow University of Technology, al. Powstańców Warszawy 8, 35-959 Rzeszow, Poland.

The influence of irradiation should be considered in fatigue reliability analyses of reactor structures under irradiation conditions. In this study, the effects of irradiation hardening and irradiation embrittlement on fatigue performance parameters were quantified and a fatigue life prediction model was developed. Based on this model, which takes into account the cumulative effect of a neutron dose, the total fatigue damage was calculated according to Miner's linear cumulative damage law, and the reliability analysis was carried out using the Monte Carlo simulation method. Read More

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February 2021

Second tumor risk in children treated with proton therapy.

Pediatr Blood Cancer 2021 Feb 9:e28941. Epub 2021 Feb 9.

Department of Radiation Oncology, University of Florida College of Medicine, Jacksonville, Florida, USA.

Background: Out-of-field neutron dissemination during double-scattered proton therapy has raised concerns of increased second malignancies, disproportionally affecting pediatric patients due to the proportion of body exposed to scatter dose and inherent radiosensitivity of developing tissue. We sought to provide empiric data on the incidence of early second tumors.

Methods: Between 2006 and 2019, 1713 consecutive children underwent double-scattered proton therapy. Read More

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February 2021

Data-Driven Approaches to Predict Thermal Maturity Indices of Organic Matter Using Artificial Neural Networks.

ACS Omega 2020 Oct 30;5(40):26169-26181. Epub 2020 Sep 30.

King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia.

Prediction of thermal maturity index parameters in organic shales plays a critical role in defining the hydrocarbon prospect and proper economic evaluation of the field. Hydrocarbon potential in shales is evaluated using the percentage of organic indices such as total organic carbon (TOC), thermal maturity temperature, source potentials, and hydrogen and oxygen indices. Direct measurement of these parameters in the laboratory is the most accurate way to obtain a representative value, but, at the same time, it is very expensive. Read More

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October 2020