667 research outputs found

    Numerical simulation and experimental validation of texture in extruded wires of a bcc metal

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    We present a comparison between a viscoplastic crystal plasticity finite element simulation of the extrusion process applied to a bcc polycrystal and the experimental evaluation of the preferred orientation (texture) in a tungsten wire by monochromatic synchrotron X-ray diffraction with an area detector. We perform a numerical simulation of sample texture evolution during large extrusion deformation with the elongation factor up to the value of fifty. By matching the predicted Orientation Distribution Functions (ODF) and the pole figures generated on the basis of the simulations to the experimental observations, the extrusion strain experienced by the sample during processing can be estimated

    On Comments in Visual Languages

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    Visual languages based on node-link diagrams can be used to develop software and, like textual languages, offer the possibility to write explanatory comments. Which node a comment refers to is usually not made explicit, but is implicitly clear to readers through placement and content. While automatic layout algorithms can make working with diagrams more productive, they tend to destroy such implicit clues because they are not aware of them and thus do not preserve the relative placement of comments and the nodes they refer to. Implicit clues thus need to be inferred and made explicit to be taken into account by layout algorithms. This is what we call the comment attachment problem. In this paper, we improve upon a previous paper on the subject [9], introducing further heuristics that aim to describe relations between comments and nodes. Based on an analysis of comment placement in a set of example diagrams, we develop a general comment attachment framework and evaluate the quality of its inferred attachments

    Crain-based nanoscale multilayer coatings dedicated to wear and oxidation protection.

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    This study explores the wear and oxidation resistance of novel CrAlYN/CrN nanoscale multilayer coatings grown by a combined high power impulse magnetron sputtering (HIPIMS) / unbalanced magnetron (UBM) sputtering process. Firstly, it is found that a HIPIMS substrate etching pre-treatment prior to the coating deposition effectively removes contaminants from the substrate surface and provides the base for epitaxial growth. Subsequently, an improvement in the adhesion and the tribological performance of CrAlYN/CrN is observed compared to coatings pre-treated with a conventional cathodic arc pre-treatment.Secondly, the effect of the deposition conditions on the microstructure and the subsequently arising coating properties is investigated. A variation in the energy of ions impinging at the substrate during the coating growth permits a change in the microstructure from polycrystalline columnar to partially single crystalline. Depending on the microstructure, CrAlYN/CrN reveals a maximum high hardness of 51 GPa and extremely low wear rated of 10[-17] m3N[-1]m[-1]. Modifications of the microstructure from nano-layered columnar to near-monolithic columnar are discovered with a change in the chemical composition. These structural changes only have a mild effect on the mechanical and tribological performance. Finally, the oxidation performance of CrAlYN/CrN is extensively investigated. Annealing in air leads to simultaniously occurring processes with (i) the thermal degradation of the nanolayered CrAlYN/CrN into Cr[2]N and AIN and (ii) the surface oxidation with the formation of corundum-type oxides and at long exposure times (iii) diffusion of substrate elements through the coating. The observed phase transformation into Cr[2]N and AIN may be promoted by the diffusion of the substrate element Cr into the coating. The results suggest that the oxidation performance of CrAlYN/CrN can be improved if the coating is grown under high energetic bombardment. The coating is prevented from cracking and therefore protects the substrate material more effectively from oxidative attack. Furthermore, it is found that the oxidation resistance can also be improved when changing the chemical composition. Highly Al-containing coatings form Cr[2]O[3]-Al[2]O[3] oxides which protect the underlying more effectively than (Cr,Al)[2]O[3] oxides grown on low Al-containing CrAlYN/CrN

    Simultaneous differential scanning calorimetry – synchrotron X-ray powder diffraction : a powerful technique for physical form characterisation in pharmaceutical materials

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    © 2016 American Chemical Society. We report a powerful new technique: hyphenating synchrotron X-ray powder diffraction (XRD) with differential scanning calorimetry (DSC). This is achieved with a simple modification to a standard laboratory DSC instrument, in contrast to previous reports which have involved extensive and complex modifications to a DSC to mount it in the synchrotron beam. The high-energy X-rays of the synchrotron permit the recording of powder diffraction patterns in as little as 2 s, meaning that thermally induced phase changes can be accurately quantified and additional insight on the nature of phase transitions obtained. Such detailed knowledge cannot be gained from existing laboratory XRD instruments, since much longer collection times are required. We demonstrate the power of our approach with two model systems, glutaric acid and sulfathiazole, both of which show enantiotropic polymorphism. The phase transformations between the low and high temperature polymorphs are revealed to be direct solid-solid processes, and sequential refinement against the diffraction patterns obtained permits phase fractions at each temperature to be calculated and unit cell parameters to be accurately quantified as a function of temperature. The combination of XRD and DSC has further allowed us to identify mixtures of phases which appeared phase-pure by DSC

    Besides variety, also season and ripening stage have a major influence on fruit pulp aroma of cacao (Theobroma cacao L.)

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    More than 1000 different cacao varieties are described. Only few are considered as fine or flavour cocoas, meaning they have the potential to develop special flavour characteristics after appropriate fermenta-tion and drying. It is assumed that aroma compounds located in the fruit pulp migrate into the seed during fermentation. We studied the fine aroma potential of five cacao varieties selected at CATIE, Costa Rica, by analysing aroma compounds in their fresh fruit pulps using Headspace SPME-GCMS. Pulps of unripe, ripe and overripe fruits harvested in the dry and rainy season, respectively, were compared to the control genotypes EET 62 and SCA-6, both known for high amounts of fine aromas described as e.g. “fruity”, “floral” or “spicy”. All genotypes contained a basic content of the two dominating esters 2-pentanol acetate and 2-heptanol acetate, combined with a mixture of aroma-active compounds with small peak areas that form the variety-specific aroma character. Total aroma diversity and intensity increased during ripening. Aroma profiles were more diverse when fruits ripened during the dry season, whereas aroma intensity was higher in the rainy season. Thus, the fruit and environmental condi-tions prior to harvest can already play a decisive role for the aroma potential of the cacao pulp. Due to their aroma profiles, the varieties from CATIE can be classified as fine or flavour cocoas

    PREDICTING PARTICIPATION IN AND SUCCESS OF A CONCURRENT SMOKING CESSATION PROGRAM DURING INPATIENT TREATMENT FOR ALCOHOL DEPENDENCE

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    Background: Predicting participation in and success of smoking cessation programs in alcohol dependent patients has yielded heterogeneous results. Moreover, these findings have rarely been based on prospective studies from clinical routine settings. Identifying predictors in prospective studies could help to tailor interventions that increase participation and success rates of smoking cessation therapies for these patients at a high risk for alcohol- and smoking-related morbidities and mortalities. Subjects and methods: During inpatient alcohol dependence treatment, 99 nicotine dependent patients were recruited. 73 patients chose to participate in a voluntary smoking cessation program. Interviews and questionnaires were used at baseline and at discharge to assess a large set of variables covering smoking and alcohol related factors, general psychopathology, quality of life and personality traits. Multiple logistic regression models were calculated to predict participation in the smoking cessation program and smoking abstinence at follow-up three months after discharge. Results: Participation in the smoking cessation program was predicted by higher stage of change, higher confidence in abstaining from smoking and lower perceived stress. Successful smoking cessation at follow-up was predicted by higher expectations of negative physical feelings due to smoking and lower expectations of temptations to smoke at baseline, and by lower number of daily smoked cigarettes at discharge. Conclusion: Despite the small sample size, this prospective study gives a first indication of clinically relevant predictors of participation in and success of a smoking cessation program by exploring many previously reported predictors simultaneously. The findings and their implications for treatment allocation and optimization are discussed. Key words

    Full-length amelogenin influences the differentiation of human dental pulp stem cells

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    Background: Amelogenin is an extracellular matrix protein well known for its role in the organization and mineralization of enamel. Clinically, it is used for periodontal regeneration and, due to its finding also in predentin and intercellular spaces of dental pulp cells, it has recently been suggested for pulp capping procedures. The aim of this study was to analyse in vitro the effect of the recombinant human full-length amelogenin on the growth and differentiation of human dental pulp stem cells (hDPSCs). Methods: Human DPSCs were treated with a supplement of amelogenin at a concentration of 10 ng/ml, 100 ng/ml and 1000 ng/ml. The groups were compared to the unstimulated control in terms of cell morphology and proliferation, mineralization and gene expression for ALP (alkaline phosphatase), DMP1 (dentin matrix protein-1) and DSPP (dentin sialophosphoprotein). Results: Amelogenin affects hDPSCs differently than PDL (periodontal ligament) cells and other cell lines. The proliferation rate at two weeks is significantly reduced in presence of the highest concentration of amelogenin as compared to the unstimulated control. hDPSCs treated with low concentrations present a downregulation of DMP1 and DSPP, which is significant for DSPP (p = 0.011), but not for DMP1 (p = 0.395). Conclusions: These finding suggest that the role of full-length amelogenin is not restricted to participation in tooth structure. It influences the differentiation of hDPSC according to various concentrations and this might impair the clinical results of pulp capping
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