Effects of Thermal Process Parameters on Mechanical Interlayer Strength for Additively Manufactured Ultem 9085

The effects of the envelope temperature on the microstructure and mechanical strength of Ultem 9085 fused deposition modeling (FDM) components were studied. A customized build chamber was developed for a commercial 3D printer in order to control the envelope temperature during printing. Test specimens were printed in the vertical direction because their mechanical strength exhibited the greatest dependence on inter-layer adhesion and neck development. A delay was introduced between two layers in each specimen in order to create a weak region where the neck was not expected to fully develop. However, none of the specimens failed in this region. Mechanical testing revealed that neck growth was highly dependent on the envelope temperature, and the strength was shown to vary significantly (20%) based on the envelope temperature. The variability of the mechanical strength also decreased as the envelope temperature increased. Thermal imaging revealed that the cooling rate of the specimens was consistent regardless of the envelope temperature. Fracture analysis confirmed that higher envelope temperatures improved the amount of neck growth and inter-layer adhesion in the specimens. This study showed that increasing the envelope temperature created parts with higher strengths and improved consistencies

Simvastatin ameliorates established pulmonary hypertension through a heme oxygenase-1 dependent pathway in rats

<p>Abstract</p> <p>Background</p> <p>Simvastatin has been shown to ameliorate pulmonary hypertension by several mechanisms in experimental animal models. In this study, we hypothesized that the major benefits of simvastatin in pulmonary hypertension occur via the heme oxygenase-1 pathway.</p> <p>Methods</p> <p>Simvastatin (10 mg/kgw/day) was tested in two rat models of pulmonary hypertension (PH): monocrotaline administration and chronic hypoxia. The hemodynamic changes, right heart hypertrophy, HO-1 protein expression, and heme oxygenase (HO) activity in lungs were measured in both models with and without simvastatin treatment. Tin-protoporphyrin (SnPP, 20 μmol/kg w/day), a potent inhibitor of HO activity, was used to confirm the role of HO-1.</p> <p>Results</p> <p>Simvastatin significantly ameliorated pulmonary arterial hypertension from 38.0 ± 2.2 mm Hg to 22.1 ± 1.9 mm Hg in monocrotaline-induced PH (MCT-PH) and from 33.3 ± 0.8 mm Hg to 17.5 ± 2.9 mm Hg in chronic hypoxia-induced PH (CH-PH) rats. The severity of right ventricular hypertrophy was significantly reduced by simvastatin in MCT-PH and CH-PH rats. Co-administration with SnPP abolished the benefits of simvastatin. Simvastatin significantly increased HO-1 protein expression and HO activity in the lungs of rats with PH; however co-administration of SnPP reduced HO-1 activity only. These observations indicate that the simvastatin-induced amelioration of pulmonary hypertension was directly related to the activity of HO-1, rather than its expression.</p> <p>Conclusion</p> <p>This study demonstrated that simvastatin treatment ameliorates established pulmonary hypertension primarily through an HO-1-dependent pathway.</p

Association of microsomal epoxide hydrolase polymorphisms and lung cancer risk

lung cancer ris

ICF, An Immunodeficiency Syndrome: DNA Methyltransferase 3B Involvement, Chromosome Anomalies, and Gene Dysregulation

The immunodeficiency, centromeric region instability, and facial anomalies syndrome (ICF) is the only disease known to result from a mutated DNA methyltransferase gene, namely, DNMT3B. Characteristic of this recessive disease are decreases in serum immunoglobulins despite the presence of B cells and, in the juxtacentromeric heterochromatin of chromosomes 1 and 16, chromatin decondensation, distinctive rearrangements, and satellite DNA hypomethylation. Although DNMT3B is involved in specific associations with histone deacetylases, HP1, other DNMTs, chromatin remodelling proteins, condensin, and other nuclear proteins, it is probably the partial loss of catalytic activity that is responsible for the disease. In microarray experiments and real-time RT-PCR assays, we observed significant differences in RNA levels from ICF vs. control lymphoblasts for pro- and anti-apoptotic genes (BCL2L10, CASP1, and PTPN13); nitrous oxide, carbon monoxide, NF-κB, and TNFa signalling pathway genes (PRKCH, GUCY1A3, GUCY1B3, MAPK13; HMOX1, and MAP4K4); and transcription control genes (NR2F2 and SMARCA2). This gene dysregulation could contribute to the immunodeficiency and other symptoms of ICF and might result from the limited losses of DNA methylation although ICF-related promoter hypomethylation was not observed for six of the above examined genes. We propose that hypomethylation of satellite 2at1qh and 16qh might provoke this dysregulation gene expression by trans effects from altered sequestration of transcription factors, changes in nuclear architecture, or expression of noncoding RNAs

Design and Characterization of a Space-based Imaging Experiment Computer Unit

The space-based chromotomographic experiment (CTEx), a hyperspectral imager, is currently in development at the Air Force Institute of Technology. This paper details an investigation of hermetic enclosures to house commercial off-the-shelf (COTS) components. These enclosures will enable the use of electronics in space which may not be available in a space-qualified form for years and reduce cost/schedule constraints. This activity produced an experimentally validated thermal mathematical model supporting further trade-space refinement and operational planning aspects for this device. Results support the transition of this next-generation technology from the laboratory to a fully-realized, space-readied platform uniquely capable of generating hyperspectral data at high spectral and temporal resolutions. © 2014 American Society of Civil Engineers

Topological quadrangulations of closed triangulated surfaces using the Reeb graph

Although surfaces are more and more often represented by dense triangulations, it can be useful to convert them to B-spline surface patches, lying on quadrangles. This paper presents a method for the construction of coarse topological quadrangulations of closed triangulated surfaces, based on Morse theory. In order to construct on the surface a quadrangulation of its canonical polygonal schema, we compute first a Reeb graph then a canonical set of generators embedded on the surface. Some results are shown on different surfaces

Isolation of the him-4 suppressor mutation which rescues the vitality of C. elegans

The nematode Caenorhabditis contains hemicentin, which is a protein that aids in gonad development, as well as tissue formation. The him-4 gene, associated with the production of hemicentin, was used to observe the effects of mutagenesis on C. elegans development and to isolate progeny that suppressed it. Five suppressors of him-4 (e1267) were isolated, and its phenotypes were compared to N2 (wild-type) and him-4. Phenotypic analyses revealed there had been a significant amount of suppression of the him-4 mutation. The results of the RNAi indicate some of the suppressors had an increased number of offspring when compared to him-4 mutants by the five suppressors. RNAi pat-3 and ina-1 indicated that some of the suppressors had an increased number of offspring when compared to the him-4 mutants. The overall results of the phenotypic assays, RNAi and hatch rates indicate some degree of suppression and seem to support the possibility of reversing the effects of him-4. Further research into the mechanisms of suppression and gene interaction, could result in significant information could then be applied to the human ortholog of hemicentin