336 research outputs found
Spina bifida-predisposing heterozygous mutations in Planar Cell Polarity genes and Zic2 reduce bone mass in young mice
Fractures are a common comorbidity in children with the neural tube defect (NTD) spina bifida. Mutations in the Wnt/planar cell polarity (PCP) pathway contribute to NTDs in humans and mice, but whether this pathway independently determines bone mass is poorly understood. Here, we first confirmed that core Wnt/PCP components are expressed in osteoblasts and osteoclasts in vitro. In vivo, we performed detailed µCT comparisons of bone structure in tibiae from young male mice heterozygous for NTD-associated mutations versus WT littermates. PCP signalling disruption caused by Vangl2 (Vangl2Lp/+) or Celsr1 (Celsr1Crsh/+) mutations significantly reduced trabecular bone mass and distal tibial cortical thickness. NTD-associated mutations in non-PCP transcription factors were also investigated. Pax3 mutation (Pax3Sp2H/+) had minimal effects on bone mass. Zic2 mutation (Zic2Ku/+) significantly altered the position of the tibia/fibula junction and diminished cortical bone in the proximal tibia. Beyond these genes, we bioinformatically documented the known extent of shared genetic networks between NTDs and bone properties. 46 genes involved in neural tube closure are annotated with bone-related ontologies. These findings document shared genetic networks between spina bifida risk and bone structure, including PCP components and Zic2. Genetic variants which predispose to spina bifida may therefore independently diminish bone mass
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Influence of a Cerium surface treatment on the oxidation behavior of commercial Fe- and Ni-base alloys
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Surface Modifications for Oxidation Resistance
None provided. Presentation only - PDF of slide presentation attached
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The Performance of Ce Surface Treated Ferritic Stainless Steels for Solid Oxide Fuel Cell Interconnects
This research deals with the effect of a Ce surface treatment on the behavior of Fe-Cr-Mn ferritic stainless steels which may have application in SOFC technology. This treatment consisted of applying a slurry of CeO2 and a halide activator to the surface of coupons. After the slurry dried the coupons were heated to 900C in a controlled atmosphere furnace for 12 hours. The effectiveness of the treatment on commercial (Type 409 (12Cr), Type 430 (18Cr), Crofer 22APU (22Cr), Type 446(26Cr)) and experimental (NETL F9 (12Cr) and NETL F5 (22Cr)) alloys as a function of Cr content will be presented. The oxidation behavior of the alloys was assessed by exposing coupons (untreated and treated) to moist air at 800C. Area specific resistance (ASR) was measured at 800C. In general, the rare earth treatment effectively reduced the oxidation rate, resulting in thinner oxide scales and less internal oxidation
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Influence of alloy content and a cerium surface treatment on the oxidation behavior of Fe-Cr ferritic stainless steels
The cost of solid oxide fuel cells (SOFC) can be significantly reduced by using interconnects made from ferritic stainless steels. In fact, several alloys have been developed specifically for this application (Crofer 22APU and Hitachi ZMG323). However, these steels lack environmental stability in SOFC environments, and as a result, degrade the performance of the SOFC. A steel interconnect can contribute to performance degradation through: (i) Cr poisoning of electrochemically active sites within the cathode; (ii) formation of non-conductive oxides, such as SiO2 or Al2O3 from residual or minor alloying elements, at the base metal-oxide scale interface; and/or (iii) excessive oxide scale growth, which may also retard electrical conductivity. Consequently, there has been considerable attention on developing coatings to protect steel interconnects in SOFC environments and controlling trace elements during alloy production. Recently, we have reported on the development of a Cerium surface treatment that improves the oxidation behavior of a variety alloys, including Crofer 22APU [1-5]. Initial results indicated that the treatment may improve the performance of Crofer 22APU for SOFC application by: (i) retarding scale growth resulting in a thinner oxide scale; and (ii) suppressing the formation of a deleterious continuous SiO2 layer that can form at the metal-oxide scale interface in materials with high residual Si content [5]. Crofer 22 APU contains Fe-22Cr-0.5Mn-0.1Ti (weight percent). Depending on current market prices and the purity of raw materials utilized for ingot production, Cr can contribute upwards of 90 percent of the raw materials cost. The present research was undertaken to determine the influence of Cr content and minor element additions, especially Ti, on the effectiveness of the Ce surface treatment. Particular emphasis is placed on the behavior of low Cr alloys
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Development of low coefficient of thermal expansion (CTE) nickel alloys for potential use as interconnects in SOFC
This paper deals with the development of low coefficient of thermal expansion (CTE) nickel-base superalloys for potential use as interconnects for SOFC. Ni-Mo-Cr alloys were formulated with CTE on the order of 12.5 to 13.5 x10-6/°C. The alloys were vacuum induction melted and reduced to sheet via a combination of hot and cold working. Dilatometry was used to measure CTE of the alloys. Oxidation behavior of the alloys at 800°C in dry and moist air is reported. The results are compared to results for Haynes 230 (a commercial Ni-base superalloy) and for Crofer 22APU (a commercial ferritic stainless steel designed specifically for use as an SOFC interconnect)
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Microchannel devices
The fabrication of stainless steel microchannel heat exchangers was examined through microlamination, the process of diffusion bonding precision machined metallic foils. The influence of diffusion bonding parameters, as well as the device geometry on the strength of the bond between the foils and embedded channel integrity, was investigated. During diffusion bonding, high temperatures and/or pressures result in well bonded foils, but these conditions cause the embedded channels to deform, which will degrade the efficiency of fluid flow through the channels. Alternatively, low temperatures and/or pressures result in undeformed channels but weakly bonded foils. This causes failure of the device due to fluid leakage. Thus, a processing envelope exists for producing a sound device with no fluid leakage and no degradation of fluid flow properties. The theoretical limit on aspect ratio within two-fluid counter-flow microchannel heat exchangers was also investigated. A counter-flow device is comprised of alternating layers of microchannels, which allow the two fluids to flow in opposite directions separated by fins. A theoretical model for interpreting the span of the fin as a function of the fin thickness was established. The model was verified experimentally by fabricating specimens to simulate the counter-flow device. The results of these investigations were used to aid in the design and processing of prototype microchannel devices
A Dutch guideline for the treatment of scoliosis in neuromuscular disorders
<p>Abstract</p> <p>Background</p> <p>Children with neuromuscular disorders with a progressive muscle weakness such as Duchenne Muscular Dystrophy and Spinal Muscular Atrophy frequently develop a progressive scoliosis. A severe scoliosis compromises respiratory function and makes sitting more difficult. Spinal surgery is considered the primary treatment option for correcting severe scoliosis in neuromuscular disorders. Surgery in this population requires a multidisciplinary approach, careful planning, dedicated surgical procedures, and specialized after care.</p> <p>Methods</p> <p>The guideline is based on scientific evidence and expert opinions. A multidisciplinary working group representing experts from all relevant specialties performed the research. A literature search was conducted to collect scientific evidence in answer to specific questions posed by the working group. Literature was classified according to the level of evidence.</p> <p>Results</p> <p>For most aspects of the treatment scientific evidence is scarce and only low level cohort studies were found. Nevertheless, a high degree of consensus was reached about the management of patients with scoliosis in neuromuscular disorders. This was translated into a set of recommendations, which are now officially accepted as a general guideline in the Netherlands.</p> <p>Conclusion</p> <p>In order to optimize the treatment for scoliosis in neuromuscular disorders a Dutch guideline has been composed. This evidence-based, multidisciplinary guideline addresses conservative treatment, the preoperative, perioperative, and postoperative care of scoliosis in neuromuscular disorders.</p
Rural-metropolitan health differential for young persons with eating disorders referred for specialist treatment
Objective: The aim was to explore associations between residing in a rural area and clinical characteristics of children and adolescents with eating disorders presenting to a specialist eating disorders program. Method: The data source was the Helping to Outline Paediatric Eating Disorders (HOPE) Project registry (N ~ 1000), a prospective ongoing registry study comprising consecutive paediatric tertiary eating disorder referrals. The sample (N = 399) comprised children and adolescents presenting with a DSM-5 eating disorder, with ages ranging from 8 to 16 years (M = 14.49, 92% female). Results Consistent with the hypotheses, living in a rural area was associated with a lower body mass index z-score, and a higher likelihood of medical complications at intake assessment. Contrary to our hypothesis, eating pathology and living in a rural area were negatively associated. No relationship was observed between living in a rural area and duration of illness or greater percentage of bodyweight lost. Conclusions: The results suggest that living in a rural area and being a greater distance from specialist services is associated with more severe malnutrition and medical complications by the time the young person and their family obtain specialist care. These findings have implications for service planning and provision for rural communities. The modifications to service delivery in the study setting will be described
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