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Radiation Research May 2021As the U.S. prepares for the possibility of a radiological or nuclear incident, or anticipated lunar and Mars missions, the exposure of individuals to neutron radiation...
As the U.S. prepares for the possibility of a radiological or nuclear incident, or anticipated lunar and Mars missions, the exposure of individuals to neutron radiation must be considered. More information is needed on how to determine the neutron dose to better estimate the true biological effects of neutrons and mixed-field (i.e., neutron and photon) radiation exposures. While exposure to gamma-ray radiation will cause significant health issues, the addition of neutrons will likely exacerbate the biological effects already anticipated after radiation exposure. To begin to understand the issues and knowledge gaps in these areas, the National Institute of Allergy and Infectious Diseases (NIAID), Radiation Nuclear Countermeasures Program (RNCP), Department of Defense (DoD), Defense Threat Reduction Agency (DTRA), and National Aeronautics and Space Administration (NASA) formed an inter-agency working group to host a Neutron Radiobiology and Dosimetry Workshop on March 7, 2019 in Rockville, MD. Stakeholder interests were clearly positioned, given the differences in the missions of each agency. An overview of neutron dosimetry and neutron radiobiology was included, as well as a historical overview of neutron exposure research. In addition, current research in the fields of biodosimetry and diagnostics, medical countermeasures (MCMs) and treatment, long-term health effects, and computational studies were presented and discussed.
Topics: Gamma Rays; Humans; Neutrons; Radiobiology; Radiometry
PubMed: 33587743
DOI: 10.1667/RADE-20-00213.1 -
Molecules (Basel, Switzerland) Aug 2022The production of reactor-based medical isotopes is fragile, which has meant supply shortages from time to time. This paper reviews alternative production methods in the... (Review)
Review
The production of reactor-based medical isotopes is fragile, which has meant supply shortages from time to time. This paper reviews alternative production methods in the form of cyclotrons, linear accelerators and neutron generators. Finally, the status of the production of medical isotopes in China is described.
Topics: China; Cyclotrons; Isotopes; Neutrons; Particle Accelerators; Radioisotopes
PubMed: 36014532
DOI: 10.3390/molecules27165294 -
Advances in Colloid and Interface... Dec 2023Self-assemblies of de novo designed short peptides at interface and in bulk solution provide potential platforms for developing applications in many medical and... (Review)
Review
Self-assemblies of de novo designed short peptides at interface and in bulk solution provide potential platforms for developing applications in many medical and technological areas. However, characterising how bioinspired supramolecular nanostructures evolve with dynamic self-assembling processes and respond to different stimuli remains challenging. Neutron scattering technologies including small angle neutron scattering (SANS) and neutron reflection (NR) can be advantageous and complementary to other state-of-the-art techniques in tracing structural changes under different conditions. With more neutron sources now available, SANS and NR are becoming increasingly popular in studying self-assembling processes of diverse peptide and protein systems, but the difficulty in experimental manipulation and data analysis can deter beginners. This review will introduce the basic theory, general experimental setup and data analysis of SANS and NR, followed by provision of their applications in characterising interfacial and solution self-assemblies of representative peptides and proteins. SANS and NR are remarkably effective in determining the morphological features self-assembled short peptides, especially size and shape transitions as a result of either sequence changes or in response to environmental stimuli, demonstrating the unique capability of NR and SANS in unravelling the interactive processes. These examples highlight the potential of NR and SANS in supporting the development of novel short peptides and proteins as biopharmaceutical candidates in the fight against many diseases and infections that share common features of membrane interactive processes.
Topics: Peptides; Proteins; Neutrons; Scattering, Small Angle
PubMed: 37931380
DOI: 10.1016/j.cis.2023.103033 -
Scientific Reports Apr 2022Neutron Capture Enhanced Particle Therapy (NCEPT) boosts the effectiveness of particle therapy by capturing thermal neutrons produced by beam-target nuclear interactions...
Neutron Capture Enhanced Particle Therapy (NCEPT) boosts the effectiveness of particle therapy by capturing thermal neutrons produced by beam-target nuclear interactions in and around the treatment site, using tumour-specific [Formula: see text]B or [Formula: see text]Gd-based neutron capture agents. Neutron captures release high-LET secondary particles together with gamma photons with energies of 478 keV or one of several energies up to 7.94 MeV, for [Formula: see text]B and [Formula: see text]Gd, respectively. A key requirement for NCEPT's translation is the development of in vivo dosimetry techniques which can measure both the direct ion dose and the dose due to neutron capture. In this work, we report signatures which can be used to discriminate between photons resulting from neutron capture and those originating from other processes. A Geant4 Monte Carlo simulation study into timing and energy thresholds for discrimination of prompt gamma photons resulting from thermal neutron capture during NCEPT was conducted. Three simulated [Formula: see text] mm[Formula: see text] cubic PMMA targets were irradiated by [Formula: see text]He or [Formula: see text]C ion beams with a spread out Bragg peak (SOBP) depth range of 60 mm; one target is homogeneous while the others include [Formula: see text] mm[Formula: see text] neutron capture inserts (NCIs) of pure [Formula: see text]B or [Formula: see text]Gd located at the distal edge of the SOBP. The arrival times of photons and neutrons entering a simulated [Formula: see text] mm[Formula: see text] ideal detector were recorded. A temporal mask of 50-60 ns was found to be optimal for maximising the discrimination of the photons resulting from the neutron capture by boron and gadolinium. A range of candidate detector and thermal neutron shielding materials were simulated, and detections meeting the proposed acceptance criteria (i.e. falling within the target energy window and arriving 60 ns post beam-off) were classified as true or false positives, depending on their origin. The ratio of true/false positives ([Formula: see text]) was calculated; for targets with [Formula: see text]B and [Formula: see text]Gd NCIs, the detector materials which resulted in the highest [Formula: see text] were cadmium-shielded CdTe and boron-shielded LSO, respectively. The optimal irradiation period for both carbon and helium ions was 1 µs for the [Formula: see text]B NCI and 1 ms for the [Formula: see text]Gd NCI.
Topics: Boron; Cadmium Compounds; Monte Carlo Method; Neutrons; Quantum Dots; Tellurium
PubMed: 35393505
DOI: 10.1038/s41598-022-09676-x -
Cancer Communications (London, England) Sep 2020The development of new accelerators has given a new impetus to the development of new drugs and treatment technologies using boron neutron capture therapy (BNCT). We... (Review)
Review
The development of new accelerators has given a new impetus to the development of new drugs and treatment technologies using boron neutron capture therapy (BNCT). We analyzed the current status and future directions of BNCT for cancer treatment, as well as the main issues related to its introduction. This review highlights the principles of BNCT and the key milestones in its development: new boron delivery drugs and different types of charged particle accelerators are described; several important aspects of BNCT implementation are discussed. BCNT could be used alone or in combination with chemotherapy and radiotherapy, and it is evaluated in light of the outlined issues. For the speedy implementation of BCNT in medical practice, it is necessary to develop more selective boron delivery agents and to generate an epithermal neutron beam with definite characteristics. Pharmacological companies and research laboratories should have access to accelerators for large-scale screening of new, more specific boron delivery agents.
Topics: Boron Neutron Capture Therapy; Humans; Neoplasms; Neutrons
PubMed: 32805063
DOI: 10.1002/cac2.12089 -
The Plant Journal : For Cell and... Jul 2022Quantifying root water uptake is essential to understanding plant water use and responses to different environmental conditions. However, non-destructive measurement of... (Review)
Review
Quantifying root water uptake is essential to understanding plant water use and responses to different environmental conditions. However, non-destructive measurement of water transport and related hydraulics in the soil-root system remains a challenge. Neutron imaging, with its high sensitivity to hydrogen, has become an unparalleled tool to visualize and quantify root water uptake in vivo. In combination with isotopes (e.g., deuterated water) and a diffusion-convection model, root water uptake and hydraulic redistribution in root and soil can be quantified. Here, we review recent advances in utilizing neutron imaging to visualize and quantify root water uptake, hydraulic redistribution in roots and soil, and root hydraulic properties of different plant species. Under uniform soil moisture distributions, neutron radiographic studies have shown that water uptake was not uniform along the root and depended on both root type and age. For both tap (e.g., lupine [Lupinus albus L.]) and fibrous (e.g., maize [Zea mays L.]) root systems, water was mainly taken up through lateral roots. In mature maize, the location of water uptake shifted from seminal roots and their laterals to crown/nodal roots and their laterals. Under non-uniform soil moisture distributions, part of the water taken up during the daytime maintained the growth of crown/nodal roots in the upper, drier soil layers. Ultra-fast neutron tomography provides new insights into 3D water movement in soil and roots. We discuss the limitations of using neutron imaging and propose future directions to utilize neutron imaging to advance our understanding of root water uptake and soil-root interactions.
Topics: Biological Transport; Lupinus; Neutrons; Plant Roots; Soil; Water; Zea mays
PubMed: 35603461
DOI: 10.1111/tpj.15839 -
Acta Crystallographica. Section D,... Oct 2021Metalloproteins catalyze a range of reactions, with enhanced chemical functionality due to their metal cofactor. The reaction mechanisms of metalloproteins have been... (Review)
Review
Metalloproteins catalyze a range of reactions, with enhanced chemical functionality due to their metal cofactor. The reaction mechanisms of metalloproteins have been experimentally characterized by spectroscopy, macromolecular crystallography and cryo-electron microscopy. An important caveat in structural studies of metalloproteins remains the artefacts that can be introduced by radiation damage. Photoreduction, radiolysis and ionization deriving from the electromagnetic beam used to probe the structure complicate structural and mechanistic interpretation. Neutron protein diffraction remains the only structural probe that leaves protein samples devoid of radiation damage, even when data are collected at room temperature. Additionally, neutron protein crystallography provides information on the positions of light atoms such as hydrogen and deuterium, allowing the characterization of protonation states and hydrogen-bonding networks. Neutron protein crystallography has further been used in conjunction with experimental and computational techniques to gain insight into the structures and reaction mechanisms of several transition-state metal oxidoreductases with iron, copper and manganese cofactors. Here, the contribution of neutron protein crystallography towards elucidating the reaction mechanism of metalloproteins is reviewed.
Topics: Animals; Catalysis; Crystallography, X-Ray; Humans; Metalloproteins; Models, Molecular; Neutron Diffraction; Neutrons; Oxidoreductases
PubMed: 34605429
DOI: 10.1107/S2059798321009025 -
Sensors (Basel, Switzerland) Dec 2022In order to detect special nuclear materials and other radioactive materials in Security and Defense scenarios, normally, a combination of neutron and gamma-ray...
In order to detect special nuclear materials and other radioactive materials in Security and Defense scenarios, normally, a combination of neutron and gamma-ray detection systems is used. In particular, to avoid illicit traffic of special nuclear materials and radioactive sources/materials, radiation portal monitors are placed at seaports to inspect shipping-container cargo. Despite their large volume (high efficiency), these detection systems are expensive, and therefore only a fraction of these containers are inspected. In this work, a novel mobile radiation detection system is presented, based on an EJ-200 plastic scintillator for the detection of gamma rays and beta particles, and a neutron detector EJ-426HD plastic scintillator (with Li) embedded in a compact and modular moderator. The use of silicon photomultipliers in both detectors presented advantages such as lightweight, compactness, and low power consumption. The developed detection system was integrated in a highly maneuverable multirotor. Monte Carlo simulations were validated by laboratory measurements and field tests were performed using real gamma-ray and neutron sources. The detection and localization within one meter was achieved using a maximum likelihood estimation algorithm for Cs sources (4 MBq), as well as the detection of Am-beryllium (1.45 GBq) source placed inside the shipping container.
Topics: Scintillation Counting; Gamma Rays; Neutrons; Radiation Monitoring; Plastics
PubMed: 36616926
DOI: 10.3390/s23010329 -
Current Opinion in Structural Biology Jun 2022Small-angle neutron scattering (SANS) has been a beneficial tool for studying the structure of biological macromolecules in solution for several decades. Continued... (Review)
Review
Small-angle neutron scattering (SANS) has been a beneficial tool for studying the structure of biological macromolecules in solution for several decades. Continued improvements in sample preparation techniques, including deuterium labeling, neutron instrumentation and complementary techniques such as small-angle x-ray scattering (SAXS), cryo-EM, NMR and x-ray crystallography, along with the availability of more powerful structure prediction algorithms and computational resources has made SANS more important than ever as a means to obtain unique information on the structure of biological complexes in solution. In particular, the contrast variation (CV) technique, which requires a large commitment in both sample preparation and measurement time, has become more practical with the advent of these improved resources. Here, challenges and recent triumphs as well as future prospects are discussed.
Topics: Crystallography, X-Ray; Neutron Diffraction; Neutrons; Scattering, Small Angle; X-Ray Diffraction
PubMed: 35490650
DOI: 10.1016/j.sbi.2022.102375 -
IARC Monographs on the Evaluation of... 2000
Review
Topics: Animals; Dogs; Environmental Exposure; Female; Haplorhini; Humans; Male; Mice; Neoplasms, Radiation-Induced; Neutrons; Rabbits; Radiation Dosage; Rats; Risk Assessment; Risk Factors; Sensitivity and Specificity; Survival Analysis
PubMed: 10932820
DOI: No ID Found