Identification and Decomposition of Uranium Oxychloride Phases in Oxygen-Exposed UCl3 Salt Compositions.

Complementary X-ray absorption fine structure (XAFS) spectroscopy and Raman spectroscopy studies were conducted on several UCl3 concentrations in several chloride salt compositions. The samples were 5% UCl3 in LiCl (S1), 5% UCl3 in KCl (S2), 5% UCl3 in LiCl-KCl eutectic (S3), 5% UCl3 in LiCl-KCl eutectic (S4), 50% UCl3 in KCl (S5), and 20% UCl3 in KCl (S6) molar concentrations. Sample S3 had UCl3 sourced from Idaho National Laboratory (INL), and all other samples were UCl3 sourced from TerraPower. The initial compositions were prepared in an inert and oxygen-free atmosphere. XAFS measurements were performed in the atmosphere at a beamline, and Raman spectroscopy was conducted inside a glovebox. Raman spectra were able to confirm initial UCl3. XAFS and later Raman spectra measured, however, did not correctly match the literature and computational spectra for the prepared UCl3 salt. Rather, the data shows some complex uranium oxychloride phases at room temperature that transition into uranium oxides upon heating. Oxygen pollution due to failure of the sealing mechanism can result in oxidation of the UCl3 salts. The oxychlorides present may be both a function of the unknown O2 exposure concentration, depending on the source of the leak and the salt composition. Evidence of this oxychloride claim and its subsequent decomposition is justified in this work.

Occupational lung diseases in South African miners at autopsy: 2020 surveillance report

The Pathology Division at the National Institute for Occupational Health (NIOH) provides autopsy services for deceased workers who worked in controlled mines or works under the provisions of the South African Occupational Diseases in Mines and Works Act, 1973 (Act No. 78 of 1973). This report describes the ages, commodities, employment durations, and occupational cardio-respiratory diseases in miners whose organs were submitted for autopsies in 2019 and 2020. Data were exported from the PATHAUT database into STATA for analysis. Differences in the proportions of disease (expressed per 1 000) were calculated using the Pearson's chi-square test; significance was set at p ≤ 0.05. There were 759 and 557 records of deceased miners and ex-miners in 2019 and 2020, respectively. Pulmonary tuberculosis decreased from 192/1 000 in 2019 to 153/1 000 autopsies in 2020, and silicosis decreased from 246/1 000 to 223/1 000. However, neither decrease was significant. There was a significant increase in the rate of asbestosis from 50/1 000 in 2019 to 79/1 000 in 2020. Pulmonary tuberculosis (TB), emphysema, and silicosis were the most frequent diseases, with high rates. There was a non-significant decrease in occupational respiratory disease rates in 2020 from 2019, but these remain higher than the rates seen in the early 1990s. The NIOH continues to conduct autopsy surveillance on miners to support compensation for families, and the development of policy and intervention programmes in the mining industry

In Situ Determination of Speciation and Local Structure of NaCl-SrCl2 and LiF-ZrF4 Molten Salts.

Understanding the local environment of the metal atoms in salt melts is important for modeling the properties of melts and predicting their behavior and thus helping enable the development of technologies such as molten salt reactors and solar-thermal power systems and new approaches to recycling rare-earth metals. Toward that end, we have developed an in situ approach for measuring the coordination of metals in molten salt coupling X-ray absorption spectroscopy (XAS) and Raman spectroscopy. Our approach was demonstrated for two salt mixtures (1.9 and 5 mol % SrCl2 in NaCl, 0.8 and 5 mol % ZrF4 in LiF) at up to 1100 °C. Near-edge (X-ray absorption near-edge structure, XANES) and extended X-ray absorption fine structure (EXAFS) spectra were measured. The EXAFS response was modeled using ab initio FEFF calculations. Strontium's first shell is observed to be coordinated with chlorine (Sr2+-Cl-) and zirconium's first shell is coordinated by fluorine (Zr4+-F-), both having coordination numbers that decrease with increasing temperature. Multiple zirconium complexes are believed to be present in the melt, which may interfere and distort the EXAFS spectra and result in an anomalously low zirconium first shell coordination number. The use of boron nitride (BN) powder as a salt diluent for XAFS measurements was found to not interfere with measurements and thus can be used for investigations of such systems.

Mono- and Multi-Objective CFD Optimization of Graded Foam-Filled Channels.

Graded foam-filled channels are a very promising solution for improving the thermal performance of heat sinks because of their customized structures that leave large amounts of room for heat transfer enhancement. Accordingly, this paper proposes a comprehensive optimization framework to address the design of such components, which are subjected to a uniform heat flux boundary condition. The graded foam is achieved by parameterizing the spatial distributions of porosity and/or Pores Per Inch (PPI). Mono- and multi-objective optimizations are implemented to find the best combination of the foam's fluid-dynamic, geometrical and morphological design variables. The mono-objective approach addresses the Performance Evaluation Criterion (PEC) as an objective function to maximize the thermal efficiency of graded foams. The multi-objective approach addresses different objective functions by means of Pareto optimization to identify the optimal tradeoff solutions between heat transfer enhancement and pressure drop reduction. Optimizations are performed by assuming a local thermal non-equilibrium in the foam. They allowed us to achieve a 1.51 PEC value with H* = 0.50, ReH = 15000, iε = iPPI = 0.50, ε(0) = 0.85, ε(1) = 0.97, PPI(0) = 5, PPI(1) = 40, and ks→f = 104 as the design variables. For the three multi-objective functions investigated, one can extrapolate the optimum from the Pareto front via the utopia criterion, obtaining h¯ = 502 W/m2 K and Δp = 80 Pa, NuH,unif¯ = 2790 and f = 42, ⟨Ts*⟩s¯= 0.011, and Δp* = 91. The optimal solutions provide original insights and guidelines for the thermal design of graded foam-filled channels.

An evaluation of the implementation of a parent-led, games-based physical activity intervention: the Active Play at Home quasi-randomized trial.

Trial Registration: NCT02058342. Registered 6 February 2014 retrospectively registered.

Early-life glucocorticoids programme behaviour and metabolism in adulthood in zebrafish.

Glucocorticoids (GCs) in utero influence embryonic development with consequent programmed effects on adult physiology and pathophysiology and altered susceptibility to cardiovascular disease. However, in viviparous species, studies of these processes are compromised by secondary maternal influences. The zebrafish, being fertilised externally, avoids this problem and has been used here to investigate the effects of transient alterations in GC activity during early development. Embryonic fish were treated either with dexamethasone (a synthetic GC), an antisense GC receptor (GR) morpholino (GR Mo), or hypoxia for the first 120h post fertilisation (hpf); responses were measured during embryonic treatment or later, post treatment, in adults. All treatments reduced cortisol levels in embryonic fish to similar levels. However, morpholino- and hypoxia-treated embryos showed delayed physical development (slower hatching and straightening of head-trunk angle, shorter body length), less locomotor activity, reduced tactile responses and anxiogenic activity. In contrast, dexamethasone-treated embryos showed advanced development and thigmotaxis but no change in locomotor activity or tactile responses. Gene expression changes were consistent with increased (dexamethasone) and decreased (hypoxia, GR Mo) GC activity. In adults, stressed cortisol values were increased with dexamethasone and decreased by GR Mo and hypoxia pre-treatments. Other responses were similarly differentially affected. In three separate tests of behaviour, dexamethasone-programmed fish appeared 'bolder' than matched controls, whereas Mo and hypoxia pre-treated fish were unaffected or more reserved. Similarly, the dexamethasone group but not the Mo or hypoxia groups were heavier, longer and had a greater girth than controls. Hyperglycaemia and expression of GC responsive gene (pepck) were also increased in the dexamethasone group. We conclude that GC activity controls many aspects of early-life growth and development in the zebrafish and that, like other species, manipulating GC status pharmacologically, physiologically or genetically in early life leads to programmable metabolic and behavioural traits in adulthood.

Early-life perturbations in glucocorticoid activity impacts on the structure, function and molecular composition of the adult zebrafish (Danio rerio) heart.

BACKGROUND: Transient early-life perturbations in glucocorticoids (GC) are linked with cardiovascular disease risk in later life. Here the impact of early life manipulations of GC on adult heart structure, function and gene expression were assessed. METHODS AND RESULTS: Zebrafish embryos were incubated in dexamethasone (Dex) or injected with targeted glucocorticoid receptor (GR) morpholino knockdown (GR Mo) over the first 120 h post fertilisation (hpf); surviving embryos (>90%) were maintained until adulthood under normal conditions. Cardiac function, heart histology and cardiac genes were assessed in embryonic (120 hpf) and adult (120 days post fertilisation (dpf)) hearts. GR Mo embryos (120 hpf) had smaller hearts with fewer cardiomyocytes, less mature striation pattern, reduced cardiac function and reduced levels of vmhc and igf mRNA compared with controls. GR Mo adult hearts were smaller with diminished trabecular network pattern, reduced expression of vmhc and altered echocardiographic Doppler flow compared to controls. Dex embryos had larger hearts at 120 hpf (Dex 107.2 ± 3.1 vs. controls 90.2 ± 1.1 µm, p < 0.001) with a more mature trabecular network and larger cardiomyocytes (1.62 ± 0.13 cells/µm vs control 2.18 ± 0.13 cells/µm, p < 0.05) and enhanced cardiac performance compared to controls. Adult hearts were larger (1.02 ± 0.07 µg/mg vs controls 0.63 ± 0.06 µg/mg, p = 0.0007), had increased vmhc and gr mRNA levels. CONCLUSION: Perturbations in GR activity during embryonic development results in short and long-term alterations in the heart.

Analysis of unstable modes distinguishes mathematical models of flagellar motion.

The mechanisms underlying the coordinated beating of cilia and flagella remain incompletely understood despite the fundamental importance of these organelles. The axoneme (the cytoskeletal structure of cilia and flagella) consists of microtubule doublets connected by passive and active elements. The motor protein dynein is known to drive active bending, but dynein activity must be regulated to generate oscillatory, propulsive waveforms. Mathematical models of flagellar motion generate quantitative predictions that can be analysed to test hypotheses concerning dynein regulation. One approach has been to seek periodic solutions to the linearized equations of motion. However, models may simultaneously exhibit both periodic and unstable modes. Here, we investigate the emergence and coexistence of unstable and periodic modes in three mathematical models of flagellar motion, each based on a different dynein regulation hypothesis: (i) sliding control; (ii) curvature control and (iii) control by interdoublet separation (the 'geometric clutch' (GC)). The unstable modes predicted by each model are used to critically evaluate the underlying hypothesis. In particular, models of flagella with 'sliding-controlled' dynein activity admit unstable modes with non-propulsive, retrograde (tip-to-base) propagation, sometimes at the same parameter values that lead to periodic, propulsive modes. In the presence of these retrograde unstable modes, stable or periodic modes have little influence. In contrast, unstable modes of the GC model exhibit switching at the base and propulsive base-to-tip propagation.

In situ heater design for nanoscale synchrotron-based full-field transmission X-ray microscopy.

The oxidation of nickel powder under a controlled gas and temperature environment was studied using synchrotron-based full-field transmission X-ray microscopy. The use of this technique allowed for the reaction to be imaged in situ at 55 nm resolution. The setup was designed to fit in the limited working distance of the microscope and to provide the gas and temperature environments analogous to solid oxide fuel cell operating conditions. Chemical conversion from nickel to nickel oxide was confirmed using X-ray absorption near-edge structure. Using an unreacted core model, the reaction rate as a function of temperature and activation energy were calculated. This method can be applied to study many other chemical reactions requiring similar environmental conditions.

Three-dimensional microstructural imaging of sulfur poisoning-induced degradation in a Ni-YSZ anode of solid oxide fuel cells.

Following exposure to ppm-level hydrogen sulfide at elevated temperatures, a section of a solid oxide fuel cell (SOFC) Ni-YSZ anode was examined using a combination of synchrotron-based x-ray nanotomography and x-ray fluorescence techniques. While fluorescence measurements provided elemental identification and coarse spatial mapping, x-ray nanotomography was used to map the detailed 3-D spatial distribution of Ni, YSZ, and a nickel-sulfur poisoning phase. The nickel-sulfur layer was found to form a scale covering most of the exposed nickel surface, blocking most fuel reformation and hydrogen oxidation reaction sites. Although the exposure conditions precluded the ability to develop a detailed kinetic description of the nickel-sulfur phase formation, the results provide strong evidence of the detrimental effects of 100 ppm hydrogen sulfide on typical Ni-YSZ anode materials.

Characterization of 3D interconnected microstructural network in mixed ionic and electronic conducting ceramic composites.

The microstructure and connectivity of the ionic and electronic conductive phases in composite ceramic membranes are directly related to device performance. Transmission electron microscopy (TEM) including chemical mapping combined with X-ray nanotomography (XNT) have been used to characterize the composition and 3-D microstructure of a MIEC composite model system consisting of a Ce0.8Gd0.2O2 (GDC) oxygen ion conductive phase and a CoFe2O4 (CFO) electronic conductive phase. The microstructural data is discussed, including the composition and distribution of an emergent phase which takes the form of isolated and distinct regions. Performance implications are considered with regards to the design of new material systems which evolve under non-equilibrium operating conditions.

Integrated use of virtual bronchoscopy and endobronchial ultrasonography on the diagnosis of peripheral lung lesions.

Endobronchial ultrasound (EBUS) improves bronchoscopic diagnosis of peripheral lung lesions (PLLs). The procedure time is lengthened by the search through multiple bronchial branches to PLLs. Virtual bronchoscopy (VB) provides endobronchial views that simulate findings at bronchoscopy. An open source software can be employed to study VB and hence the endobronchial route to a PLL. It allows VB to be studied in a Macintosh platform such as a laptop computer. Our purpose was to test if VB generated by this software could shorten procedure time of EBUS-guided bronchoscopy as compared with no VB assistance. The most feasible route to a PLL was manually selected using this software to study VB (VB group). For non-VB group, 2D CT axial +/- coronal images were reviewed to plan bronchoscopy. Before bronchoscopic biopsies, the location of PLL was confirmed by EBUS. Thirty-three subjects were recruited including 16 in VB group and 17 in non-VB group. The mean EBUS examination time and mean total procedure time were reduced in the VB group compared with non-VB group: 5.3 versus 10.5 minutes (P=0.04) and 22.4 versus 29.9 minutes (P=0.044), respectively. There was no complication in the VB group. Although the diagnostic yield was higher in the VB group than non-VB group, our study was not powered to test the difference. This pilot study suggests that VB assistance is safe and shortens procedural time of EBUS-guided bronchoscopy for PLL. Further study is warranted to confirm these findings.

Physiological roles of glucocorticoids during early embryonic development of the zebrafish (Danio rerio).

While glucocorticoids (GCs) are known to be present in the zebrafish embryo, little is known about their physiological roles at this stage. We hypothesised that GCs play key roles in stress response, hatching and swim activity during early development. To test this, whole embryo cortisol (WEC) and corticosteroid-related genes were measured in embryos from 6 to 120 h post fertilisation (hpf) by enzyme linked immunosorbent assay (ELISA) and quantitative real-time polymerase chain reaction (qRT-PCR). Stress response was assessed by change in WEC following stirring, hypoxia or brief electrical impulses applied to the bathing water. The impact of pharmacological and molecular GC manipulation on the stress response, spontaneous hatching and swim activity at different stages of development was also assessed. WEC levels demonstrated a biphasic pattern during development with a decrease from 0 to 36 hpf followed by a progressive increase towards 120 hpf. This was accompanied by a significant and sustained increase in the expression of genes encoding cyp11b1 (GC biosynthesis), hsd11b2 (GC metabolism) and gr (GC receptor) from 48 to 120 hpf. Metyrapone (Met), an inhibitor of 11ß-hydroxylase (encoded by cyp11b1), and cyp11b1 morpholino (Mo) knockdown significantly reduced basal and stress-induced WEC levels at 72 and 120 hpf but not at 24 hpf. Spontaneous hatching and swim activity were significantly affected by manipulation of GC action from approximately 48 hpf onwards. We have identified a number of key roles of GCs in zebrafish embryos contributing to adaptive physiological responses under adverse conditions. The ability to alter GC action in the zebrafish embryo also highlights its potential value for GC research.

Three-dimensional microstructural imaging methods for energy materials.

Advances in the design of materials for energy storage and conversion (i.e., "energy materials") increasingly rely on understanding the dependence of a material's performance and longevity on three-dimensional characteristics of its microstructure. Three-dimensional imaging techniques permit the direct measurement of microstructural properties that significantly influence material function and durability, such as interface area, tortuosity, triple phase boundary length and local curvature. Furthermore, digital representations of imaged microstructures offer realistic domains for modeling. This article reviews state-of-the-art methods, across a spectrum of length scales ranging from atomic to micron, for three-dimensional microstructural imaging of energy materials. The review concludes with an assessment of the continuing role of three-dimensional imaging in the development of novel materials for energy applications.

Immune toxicities and long remission duration after ipilimumab therapy for metastatic melanoma: two illustrative cases.

New antitumour immunotherapy strategies for stage iv metastatic melanoma include ipilimumab, a monoclonal antibody against ctla-4. Patterns of response with cancer immunotherapy differ from those with cytotoxic chemotherapy. We present two cases of long-duration immune-related responses with ipilimumab in a phase ii trial. A 66-year-old woman with multiple lung metastases from a scalp primary melanoma received 4 doses of ipilimumab with mixed clinical response. However, after the first maintenance dose, she developed severe ileitis and colitis that responded to steroid therapy. Four months later, she had surgery and radiotherapy for a single brain metastasis. Radiologically, stable disease continued for 36 months after the last ipilimumab dose, and partial response for 5 years after ipilimumab start. A 54-year-old man with cervical lymph node and pulmonary metastases from a scalp primary melanoma received three induction doses of ipilimumab. He developed alopecia universalis and widespread vitiligo, and he discontinued treatment because of hypophysitis. Maintenance ipilimumab was started after a 6-month drug-free interval, with no further adverse events over 15 cycles. At week 12, computed tomography imaging showed no lung metastases and partial response in a supraclavicular lymph node, which was positive on positron-emission tomography. Five years after starting ipilimumab, the supraclavicular lymph node was calcified, and the patient was off steroid therapy and asymptomatic. The foregoing patients demonstrate long responses with ipilimumab (in association with delayed severe colitis in one case, and a constellation of immune events, including alopecia universalis in another). Re-treatment with ipilimumab may be possible even after significant immune adverse events.

Quantitative x-ray phase imaging at the nanoscale by multilayer Laue lenses.

For scanning x-ray microscopy, many attempts have been made to image the phase contrast based on a concept of the beam being deflected by a specimen, the so-called differential phase contrast imaging (DPC). Despite the successful demonstration in a number of representative cases at moderate spatial resolutions, these methods suffer from various limitations that preclude applications of DPC for ultra-high spatial resolution imaging, where the emerging wave field from the focusing optic tends to be significantly more complicated. In this work, we propose a highly robust and generic approach based on a Fourier-shift fitting process and demonstrate quantitative phase imaging of a solid oxide fuel cell (SOFC) anode by multilayer Laue lenses (MLLs). The high sensitivity of the phase to structural and compositional variations makes our technique extremely powerful in correlating the electrode performance with its buried nanoscale interfacial structures that may be invisible to the absorption and fluorescence contrasts.

Zone-doubled Fresnel zone plates for high-resolution hard X-ray full-field transmission microscopy.

Full-field transmission X-ray microscopy is a unique non-destructive technique for three-dimensional imaging of specimens at the nanometer scale. Here, the use of zone-doubled Fresnel zone plates to achieve a spatial resolution better than 20 nm in the hard X-ray regime (8-10 keV) is reported. By obtaining a tomographic reconstruction of a Ni/YSZ solid-oxide fuel cell, the feasibility of performing three-dimensional imaging of scientifically relevant samples using such high-spatial-resolution Fresnel zone plates is demonstrated.

Focused ion beam preparation of samples for X-ray nanotomography.

The preparation of hard material samples with the necessary size and shape is critical to successful material analysis. X-ray nanotomography requires that samples are sufficiently thin for X-rays to pass through the sample during rotation for tomography. One method for producing samples that fit the criteria for X-ray nanotomography is focused ion beam/scanning electron microscopy (FIB/SEM) which uses a focused beam of ions to selectively mill around a region of interest and then utilizes a micromanipulator to remove the milled-out sample from the bulk material and mount it on a sample holder. In this article the process for preparing X-ray nanotomography samples in multiple shapes and sizes is discussed. Additionally, solid-oxide fuel cell anode samples prepared through the FIB/SEM technique underwent volume-independence studies for multiple properties such as volume fraction, average particle size, tortuosity and contiguity to observe the characteristics of FIB/SEM samples in X-ray nanotomography.