Porosity measurements in suspension plasma sprayed YSZ coatings using NMR cryoporometry and X-ray microscopy

A large variety of coatings are used to protect structural engineering materials from corrosion, wear, and erosion, and to provide thermal insulation. In this work, yttria-stabilized zirconia coatings produced by suspension plasma spraying were investigated with respect to their microstructure and especially their porosity, as the porosity affects the thermal insulation of the underlying component. To determine porosity, pore size distribution, and pore shape, the coatings were investigated using novel advanced characterization techniques like NMR cryoporometry and X-ray microscopy. In general, the porosity is inhomogeneously distributed and the coatings showed a large variety of pore sizes ranging from a few nanometers to micrometers

Evidence for a Relationship between VEGF and BMI Independent of Insulin Sensitivity by Glucose Clamp Procedure in a Homogenous Group Healthy Young Men

BACKGROUND: This is the first study to experimentally explore the direct relationship between circulating VEGF levels and body mass index (BMI) as well as to unravel the role of insulin sensitivity in this context under standardized glucose clamp conditions as the methodical gold-standard. In order to control for known influencing factors such as gender, medication, and arterial hypertension, we examined a highly homogeneous group of young male subjects. Moreover, to encompass also subjects beyond the normal BMI range, low weight and obese participants were additionally included and stress hormones as a main regulator of VEGF were assessed. METHODOLOGY/PRINCIPAL FINDINGS: Under euglycemic clamp conditions, VEGF was measured in 15 normal weight (BMI 20-25 kg/m(2)), 15 low weight (BMI<20 kg/m(2)), and 15 obese (BMI>30 kg/m(2)) male subjects aged 18-30 years and the insulin sensitivity index (ISI) was calculated. Since stress axis activation promotes VEGF secretion, concentrations of ACTH, cortisol, and catecholamines were monitored. Despite of comparable ACTH (P = 0.145), cortisol (P = 0.840), and norepinephrine (P = 0.065) levels, VEGF concentrations differed significantly between BMI-groups (P = 0.008) with higher concentrations in obese subjects as compared to normal weight (P = 0.061) and low weight subjects (P = 0.002). Pearson's correlation analysis revealed a positive relationship between BMI and VEGF levels (r = 0.407; P = 0.010) but no correlation of VEGF with ISI (r = 0.224; P = 0.175). CONCLUSIONS/SIGNIFICANCE: Our data demonstrate a positive correlation between concentrations of circulating VEGF levels and BMI in healthy male subjects under highly controlled conditions. This relationship which is apparently disconnected from insulin sensitivity may be part of some pathogenetic mechanisms underlying obesity and type 2 diabetes

A truncated Kv1.1 protein in the brain of the megencephaly mouse: expression and interaction

BACKGROUND: The megencephaly mouse, mceph/mceph, is epileptic and displays a dramatically increased brain volume and neuronal count. The responsible mutation was recently revealed to be an eleven base pair deletion, leading to a frame shift, in the gene encoding the potassium channel Kv1.1. The predicted MCEPH protein is truncated at amino acid 230 out of 495. Truncated proteins are usually not expressed since nonsense mRNAs are most often degraded. However, high Kv1.1 mRNA levels in mceph/mceph brain indicated that it escaped this control mechanism. Therefore, we hypothesized that the truncated Kv1.1 would be expressed and dysregulate other Kv1 subunits in the mceph/mceph mice. RESULTS: We found that the MCEPH protein is expressed in the brain of mceph/mceph mice. MCEPH was found to lack mature (Golgi) glycosylation, but to be core glycosylated and trapped in the endoplasmic reticulum (ER). Interactions between MCEPH and other Kv1 subunits were studied in cell culture, Xenopus oocytes and the brain. MCEPH can form tetramers with Kv1.1 in cell culture and has a dominant negative effect on Kv1.2 and Kv1.3 currents in oocytes. However, it does not retain Kv1.2 in the ER of neurons. CONCLUSION: The megencephaly mice express a truncated Kv1.1 in the brain, and constitute a unique tool to study Kv1.1 trafficking relevant for understanding epilepsy, ataxia and pathologic brain overgrowth

ESPEN Guideline: Clinical Nutrition in inflammatory bowel disease

Introduction: The ESPEN guideline presents a multidisciplinary focus on clinical nutrition in inflammatory bowel disease (IBD). Methodology: The guideline is based on extensive systematic review of the literature, but relies on expert opinion when objective data were lacking or inconclusive. The conclusions and 64 recommendations have been subject to full peer review and a Delphi process in which uniformly positive responses (agree or strongly agree) were required. Results: IBD is increasingly common and potential dietary factors in its aetiology are briefly reviewed. Malnutrition is highly prevalent in IBD – especially in Crohn's disease. Increased energy and protein requirements are observed in some patients. The management of malnu-trition in IBD is considered within the general context of support for malnourished patients. Treatment of iron deficiency (parenterally if necessary) is strongly recommended. Routine provision of a special diet in IBD is not however supported. Parenteral nutrition is indicated only when enteral nutrition has failed or is impossible. The recommended perioperative man-agement of patients with IBD undergoing surgery accords with general ESPEN guidance for patients having abdominal surgery. Probiotics may be helpful in UC but not Crohn's disease. Primary therapy using nutrition to treat IBD is not supported in ulcerative colitis, but is mod-erately well supported in Crohn's disease, especially in children where the adverse conse-quences of steroid therapy are proportionally greater. However, exclusion diets are generally not recommended and there is little evidence to support any particular formula feed when nutritional regimens are constructed. Conclusions: Available objective data to guide nutritional support and primary nutritional therapy in IBD are presented as 64 recommendations, of which 9 are very strong recom-mendations (grade A), 22 are strong recommendations (grade B) and 12 are based only on sparse evidence (grade 0); 21 recommendations are good practice points (GPP)

EBSD Analysis and Assessment of Porosity in Thermal Barrier Coatings Produced by Axial Suspension Plasma Spraying (ASPS)

Axial suspension plasma spraying (ASPS) is a relatively new, innovative sprayingtechnique which has produced thermal barrier coatings (TBCs) with attractive properties such ashigh durability and low thermal conductivity. Using a suspension, it is possible to spray with finerpowder particles resulting in coatings that have a columnar microstructure and contain a wide rangeof pore sizes, both nm- and μm-sized pores. To optimize the thermal properties and to maintainthem during service of the components, it will be important to design TBCs with optimal porosity.Hence, an important part in the assessment of ASPS coatings is therefore the characterization of themicrostructure and how it is build up, and the determination of porosity. Both aspects are addressedby performing measurement on splats and ASPS-coating using electron backscatter diffraction(EBSD) technique and by measuring porosity by Mercury Intrusion Porosimetry (MIP)

Porosity investigation of yttria-stabilized zirconia topcoats using NMR cryoporometry

Axial suspension plasma spraying (ASPS) is a new, innovative plasma spray technique using a feedstockconsisting of fine powder particles suspended in a liquid. With ASPS, thermal barrier coating (TBC) topcoatswith columnar structures have been produced that are built up by fine powder particles. The microstructure consistsof micro-,meso-, and macro-pores. Due to thewide pore size range including nano-porosity it is challengingto measure porosity and pore size distribution in TBC topcoats. However, it is important to characterize the porousstructure as it affects the thermal conductivity. Nuclear magnetic resonance (NMR) cryoporometry is apromising method for performing such measurements because of its capability of measuring pores down tonanometer size and providing information about the pore geometry. The aim of this paper is to introduce NMRcryoporometry as a newcharacterization technique for determining porosity, pore size distribution and pore geometryof TBC topcoats produced by ASPS. The study includes the comparison of two different yttria-stabilizedzirconia topcoats and NMR cryoporometry is complemented by microstructural characterization using scanningelectron microscopy

EBSD Analysis and Assessment of Porosity in Thermal Barrier Coatings Produced by Axial Suspension Plasma Spraying (ASPS)

Axial suspension plasma spraying (ASPS) is a relatively new, innovative sprayingtechnique which has produced thermal barrier coatings (TBCs) with attractive properties such ashigh durability and low thermal conductivity. Using a suspension, it is possible to spray with finerpowder particles resulting in coatings that have a columnar microstructure and contain a wide rangeof pore sizes, both nm- and μm-sized pores. To optimize the thermal properties and to maintainthem during service of the components, it will be important to design TBCs with optimal porosity.Hence, an important part in the assessment of ASPS coatings is therefore the characterization of themicrostructure and how it is build up, and the determination of porosity. Both aspects are addressedby performing measurement on splats and ASPS-coating using electron backscatter diffraction(EBSD) technique and by measuring porosity by Mercury Intrusion Porosimetry (MIP)

Analysis of single splats produced by axial suspension plasma spraying

Axial suspension plasma spraying (ASPS) is a relatively new, innovative technique with which microstructures have been produced that are similar to the ones produced by electron beam physical vapor deposition. They have a columnar structure and consist of nm- and \ub5m-sized pores. However, so far the formation of the microstructure is not fully understood because fragmentation and vaporisation of the liquid significantly affects the deposition process. Analysis of single splats can provide important information on the phenomena controlling the coating formation process and the final coating properties. Therefore, the present study aims at providing first results of 8 wt-% yttria-stabilised zirconia single splats sprayed onto a steel substrate by use of ASPS. Scanning electron microscopy and atomic force microscopy have been used to characterise the splats with respect to appearance, shape, and size distribution

3D Analysis of Porosity in a Ceramic Coating Using X-ray Microscopy

Suspension plasma spraying (SPS) is a new,innovative plasma spray technique using a feedstock consisting of fine powder particles suspended in a liquid. Using SPS, ceramic coatings with columnar microstructures have been produced which are used as topcoats in thermal barrier coatings. The microstructure contains a wide pore size range consisting of inter-columnar spacings, micro-pores and nano-pores. Hence, determination of total porosity and pore size distribution is a challenge. Here, x-ray microscopy (XRM) has been applied for describing the complexpore space of the coatings because of its capability toimage the (local) porosity within the coating in 3D at aresolution down to 50 nm. The possibility to quantitativelysegment the analyzed volume allows analysis of both openand closed porosity. For an yttria-stabilized zirconia coating with feathery microstructure, both open and closedporosity were determined and it could be revealed that 11%of the pore volumes (1.4% of the total volume) are closedpores. The analyzed volume was reconstructed to illustratethe distribution of open and closed pores in 3D. Moreover,pore widths and pore volumes were determined. The resultson the complex pore space obtained by XRM are discussedin connection with other porosimetry techniques