High-intensity power-resolved radiation imaging of an operational nuclear reactor

Knowledge of the neutron distribution in a nuclear reactor is necessary to ensure the safe and efficient burnup of reactor fuel. Currently these measurements are performed by in-core systems in what are extremely hostile environments and in most reactor accident scenarios it is likely that these systems would be damaged. Here we present a compact and portable radiation imaging system with the ability to image high-intensity fast-neutron and gamma-ray fields simultaneously. This system has been deployed to image radiation fields emitted during the operation of a TRIGA test reactor allowing a spatial visualization of the internal reactor conditions to be obtained. The imaged flux in each case is found to scale linearly with reactor power indicating that this method may be used for power-resolved reactor monitoring and for the assay of ongoing nuclear criticalities in damaged nuclear reactors

Sugary Drink FACTS 2014: Some Progress but Much Room for Improvement in Marketing to Youth

This report updates a 2011 report on the same topic. Using the same methods as the last report, researchers examined changes in the nutritional content of sugar-sweetened drinks including sodas, fruit drinks, flavored waters, sports drinks, iced teas, as well as zero-calorie energy drinks and shots. They also analyzed marketing tactics for 23 companies that advertised these products, including amount spent to advertise in all media; child and teen exposure to advertising and brand appearances on TV and visits to beverage company websites, including differences for black and Hispanic youth; advertising on websites popular with children and teens; and marketing in newer media like mobile apps and social media. Researchers also examined changes in advertising of diet beverages, 100% juice, and water

Design, development and characterization of a novel neutron and X-ray combined computed tomography system

Visualizing the three dimensional structure of objects (e.g. nuclear fuel, nuclear materials, explosives and bio materials) and phenomena (e.g. particle tracking) can be very important in nondestructive testing applications. Computed tomography systems are indispensable tools for these types of applications because they provide a versatile non-destructive technique for analysis. A novel neutron and X-ray combined computed tomography (NXCT) system has been designed and developed at the Missouri University of Science & Technology. The neutron and X-ray combined computed tomography system holds much promise for non-destructive material detection and analysis where multiple materials having similar atomic number and differing thermal cross section or vice versa may be present within an object, exclusive neutron or X-ray analysis may exhibit shortcomings in distinguishing interfaces. However, fusing neutron image and X-ray image offers the strengths of both and may provide a superior method of analysis. In addition, a feasible design of a sample positioning system which allows the user to remotely and automatically manipulate the objects makes the NXCT system viable for commercial applications. Moreover, characterization of the newly developed digital imaging system is imperative to the performance evaluation, as well as for describing the associated parameters. The performance of a combined neutron/X-ray digital imaging system was evaluated in terms of modulation transfer function (MTF), noise power spectrum (NPS) and detective quantum efficiency (DQE). This dissertation is a complete overview of the design of the NXCT system, operation, algorithms, performance evaluation and results --Abstract, page iii

Ebola virus-like particles reprogram cellular metabolism

Ebola virus can trigger a release of pro-inflammatory cytokines with subsequent vascular leakage and impairment of clotting finally leading to multiorgan failure and shock after entering and infecting patients. Ebola virus is known to directly target endothelial cells and macrophages, even without infecting them, through direct interactions with viral proteins. These interactions affect cellular mechanics and immune processes, which are tightly linked to other key cellular functions such as metabolism. However, research regarding metabolic activity of these cells upon viral exposure remains limited, hampering our understanding of its pathophysiology and progression. Therefore, in the present study, an untargeted cellular metabolomic approach was performed to investigate the metabolic alterations of primary human endothelial cells and M1 and M2 macrophages upon exposure to Ebola virus-like particles (VLP). The results show that Ebola VLP led to metabolic changes among endothelial, M1, and M2 cells. Differential metabolite abundance and perturbed signaling pathway analysis further identified specific metabolic features, mainly in fatty acid-, steroid-, and amino acid-related metabolism pathways for all the three cell types, in a host cell specific manner. Taken together, this work characterized for the first time the metabolic alternations of endothelial cells and two primary human macrophage subtypes after Ebola VLP exposure, and identified the potential metabolites and pathways differentially affected, highlighting the important role of those host cells in disease development and progression.Immunogenetics and cellular immunology of bacterial infectious disease

The Journal of Conventional Weapons Destruction Issue 21.1 (2017)

Feature: Improvised Explosive Devices (IED) and Pressure Plate IED\u27s Spotlight: Bosnia and Herzegovina 2- years later Field Notes Research and Developmen

Influence of porosity on fatigue of additive manufactured titanium alloy Ti-6Al-4V

Process-induced defects have been identified as one of the principal failure sources in metal additive manufacturing (AM) under cyclic loading; yet, understanding how they impact fatigue behaviour, such as S-N curves, fatigue crack growth rates remains open. In this work, the high-cycle fatigue behaviour under constant amplitude, axial loading was studied for an AM titanium alloy Ti-6Al-4V that fails from sub-mm size, porosity type defects. More specifically, the dispersion of fatigue life due to porosity and the propagation behaviour of cracks initiated from pores were investigated.Two different AM processes, namely wire+arc additive manufacturing and laser powder-bed fusion, were used to manufacture titanium alloy Ti-6Al-4V used in this work. A trade-off was made by working with process-induced defects, e.g. defect morphologies were representative of real case scenarios, but the dimensions of defects were uncontrolled. A targeted experimental programme was developed to concentrate on the influence of defects by circumventing other parameters that might impact the fatigue life such as the surface roughness, build direction and more. Size and spatial distribution of process-induced defects were measured using a laboratory scale X-ray Computed Tomography prior to fatigue testing. Load-controlled fatigue testing was conducted by repeating tests at the selected stress levels in order to obtain statistically significant data. Furthermore, fatigue crack growth rates were measured for cracks initiating directly from surface pores using the replica technique. After each fatigue test, the crack initiating pore size was quantified by analysing the fracture surface using a scanning electron microscope. The experimental results were analysed both from a linear elastic fracture mechanics perspective and a total life perspective using the local elastic stresses in the vicinity of a pore. Key findings are summarised below.A popular approach to evaluate defect criticality is assuming a volumetric defect as a planar crack by projecting its area to the plane perpendicular to the applied load direction. This planar crack is then assessed using a Kitagawa-Takahashi diagram or similar since cracks at the sub-mm scale could grow below the threshold value of stress intensity factor range (∆Kth). It was found that the analogy of assuming pores as cracks was lost after a certain transition size and fatigue life reduction saturated despite the increase of crack initiating pore diameter roughly by a factor of four.Total fatigue life of AM Ti-6Al-4V could vary up to three orders of magnitude for nominally similar test specimens, as seen in the exploratory literature studies. Defects are considered as one of the causes of this scatter and in this work, defect location, e.g. embeddedor surface, was found to be the dominant factor rather than the defect size. In fact, within a same defect category, such as the surface pores, the scatter of fatigue life due to the variation in crack initiating defect size was less than a conventional manufactured Ti-6Al-4V, where the scatter assumed to be related to the distribution of unfavourably oriented surface grains.Individual fatigue life stages were also investigated by following surface cracks initiated from pores using the replica technique. First detected cracks were less than 50 µm length and occupied roughly 50% of the total fatigue life. This suggests that the crack initiation stage was significant and it should be accounted in fatigue life prediction approaches, noting that the measurements were limited to surface observations. During the crack propagation stage, small cracks could grow faster than the long crack growth measurements at the same nominal ∆K value, i.e. the so-called small crack behaviour. Such a behaviour was observed near the threshold region, however, it was less significant compared to conventional manufactured counterparts. Finally, a similitude to long crack growth rates was achieved,when the measured crack size added to the crack initiating pore size.<br/