In-situ observation and numerical modeling of contact creep and recovery on oriented semi-crystalline polymer surfaces

Semi-crystalline polymers are commonly used in industrial sectors where surfaces undergo many damages like scratches. In order to avoid as much as possible these surface damages, it is necessary to develop mechanical models able to predict such contact mechanical responses. The aim of this work is to study the effect of orientation, through stretching in the solid state, on the contact mechanics for semi-crystalline polymer surfaces. To that purpose, bulk polymers are uniaxially oriented at various stretching ratio, using hot two-mill rolling process, and are characterized by X-ray analysis. Contact creep and recovery tests were performed on these samples thanks to a home-made experimental device [1]. This apparatus allows an in-situ observation of the contact area during creep step on non-transparent materials. Then, the recovery of the residual imprint is quickly (few seconds after the unloading of the indenter) recorded by non-contact methods. This experiment gives access to the true contact geometry and provides valuable information about the early stage of viscoelastic recovery. Hence, the influence of surface orientation on the contact response was investigated on a model semi-crystalline polymer: HDPE to identify structural parameters that govern viscoelastic/viscoplastic behavior of the surface. The effects of strain levels and creep duration on viscoelastic behavior were also studied. As regards the latter parameter, it was shown that creep duration has no major effect on creep step. Nonetheless, for a same imposed strain, residual depths increase with longer creep duration, inducing, in some case, a permanent deformation of the surface. Regarding the effect of orientation, if the contact creep of the non-oriented surface with a spherical indentor displays a circular contact area, the same experiment performed with oriented semi-crystalline polymers shows an elliptical contact area. Two assumptions can be made to explain this contact shape: (a) the polymeric surface displays anisotropic mechanical properties or (b) the sample is isotropic but the contact takes place on a curved surface due to the rolling stage. In order to better understand the in-situ observations of the contact shape during the contact creep and recovery of the residual imprint, numerical modeling of the surface response was performed using MSC MARC® software. The aim is to reproduce, as closely as possible, the contact creep and recovery experiment. To that purpose an axisymmetric numerical model was created, considering the indentation sphere to be infinitely rigid. This model gives access to the true contact radius during the creep phase. First results seem to indicate that the elliptical shape of the contact area is rather govern by the anisotropic mechanical properties of the semi-crystalline polymer surfaces.   Acknowledgement: This research forms part of the research program of the Dutch Polymer Institute (DPI) project #783. The authors would like to acknowledge the funding support ""MARMA"" from Carnot MICA and HOLO3 (Alsace region) company for developing the instrument.   Reference: [1] : T. Chatel, C. Gauthier, H. Pelletier, V. Le Houérou, D. Favier and R. Schirrer. Journal of Physics D: Applied Physics, 2011, 44, 375-40

Attributable Outcomes of Endemic Clostridium difficile–associated Disease in Nonsurgical Patients

CDAD led to significantly worse outcomes in these patients

The Etiology of Multiple Sclerosis: Genetic Evidence for the Involvement of the Human Endogenous Retrovirus HERV-Fc1

We have investigated the role of human endogenous retroviruses in multiple sclerosis by analyzing the DNA of patients and controls in 4 cohorts for associations between multiple sclerosis and polymorphisms near viral restriction genes or near endogenous retroviral loci with one or more intact or almost-intact genes. We found that SNPs in the gene TRIM5 were inversely correlated with disease. Conversely, SNPs around one retroviral locus, HERV-Fc1, showed a highly significant association with disease. The latter association was limited to a narrow region that contains no other known genes. We conclude that HERV-Fc1 and TRIM5 play a role in the etiology of multiple sclerosis. If these results are confirmed, they point to new modes of treatment for multiple sclerosis

GDNF Overexpression from the Native Locus Reveals its Role in the Nigrostriatal Dopaminergic System Function

Peer reviewe

Nanostructures, Technology, Research, and Applications

Contains reports on the nanostructures laboratory, eighteen research projects and a list of publications.Joint Services Electronics Program Grant DAAH04-95-1-0038Semiconductor Research Corporation Contract 95-LJ-550National Science Foundation Grant ECS 94-07078U.S. Army Research Office Grant DAAH04-95-1-0564Defense Advanced Research Projects Agency/Naval Air Systems Command Contract N00019-95-K-0131National Aeronautics and Space Administration Contract NAS8-38249National Aeronautics and Space Administration Grant NAGW-2003IBM Corporation Contract 1622U.S. Navy- Office of Naval Research Grant N00014-95-1-1297U.S. Army Research Office Grant DAAH04-94-G-0377U.S. Air Force - Office of Scientific Research Grant F-49-620-92-J-0064U.S. Air Force - Office of Scientific Research Grant F-49-620-95-1-031

Nanostructures, Technology, Research, and Applications

Contains reports on twenty research projects and a list of publications.Joint Services Electronics Program Grant DAAH04-95-1-0038National Science Foundation Grant ECS-94-07078Semiconductor Research CorporationU.S. Army Research Office Grant DAAH04-95-1-0564Defense Advanced Research Projects Agency/Naval Air Systems Command Contract N00019-95-K-0131National Aeronautics and Space Administration Contract NAS8-38249National Aeronautics and Space Administration Grant NAGW-2003IBM Corporation Contract 1622National Science Foundation Graduate FellowshipU.S. Navy - Office of Naval Research Grant N00014-95-1-1297U.S. Army Research Office Contract DAAH04-94-G-0377U.S. Air Force - Office of Scientific Research Grant F49620-92-J-0064U.S. Air Force - Office of Scientific Research Grant F49620-95-1-0311National Science Foundation Contract DMR 94-0034U.S. Air Force - Office of Scientific Research Contract F49620-96-0126Harvard-Smithsonian Astrophysical Observatory Contract SV630304National Aeronautics and Space Administration Grant NAG5-5105Los Alamos National Laboratory Contract E57800017-9

Validation of the Body Concealment Scale for Scleroderma (BCSS): Replication in the Scleroderma Patient-centered Intervention Network (SPIN) Cohort

© 2016 Elsevier Ltd Body concealment is an important component of appearance distress for individuals with disfiguring conditions, including scleroderma. The objective was to replicate the validation study of the Body Concealment Scale for Scleroderma (BCSS) among 897 scleroderma patients. The factor structure of the BCSS was evaluated using confirmatory factor analysis and the Multiple-Indicator Multiple-Cause model examined differential item functioning of SWAP items for sex and age. Internal consistency reliability was assessed via Cronbach's alpha. Construct validity was assessed by comparing the BCSS with a measure of body image distress and measures of mental health and pain intensity. Results replicated the original validation study, where a bifactor model provided the best fit. The BCSS demonstrated strong internal consistency reliability and construct validity. Findings further support the BCSS as a valid measure of body concealment in scleroderma and provide new evidence that scores can be compared and combined across sexes and ages

ARIA digital anamorphosis : Digital transformation of health and care in airway diseases from research to practice

Digital anamorphosis is used to define a distorted image of health and care that may be viewed correctly using digital tools and strategies. MASK digital anamorphosis represents the process used by MASK to develop the digital transformation of health and care in rhinitis. It strengthens the ARIA change management strategy in the prevention and management of airway disease. The MASK strategy is based on validated digital tools. Using the MASK digital tool and the CARAT online enhanced clinical framework, solutions for practical steps of digital enhancement of care are proposed.Peer reviewe

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead