Linking peel and tack performances of pressure sensitive adhesives.

The performances of Pressure Sensitive Adhesives (PSA) are generally evaluated using different loading geometries such as tack, peel and shear tests. It is difficult to link the behaviors of PSAs in these different geometries, and to predict the result of one test from another, because the confinement of a soft and dissipative material prevents the use of standard fracture mechanics, which separates the interface debonding behavior from the dissipation associated with the bulk deformation. We present here an original experimental investigation based on the modeling strategy proposed by Creton and Ciccotti[1]. Using instrumented versions of both peel and tack measurements, we compared the adherence performances of a series of model PSAs based on styrene-isoprene block copolymers, while identifying the mesoscale mechanisms at play during debonding. This analysis method allows us to model the contribution of the large strain rheology of the PSAs in the total work of debonding. We clearly show that both the adherence performances and local mechanisms can be closely related between peel and tack when considering both similar confinement and a similar strain rate of the fibrils that are spontaneously formed during debonding. While the overall adherence properties change by a factor of 3 between the different samples, the peel tests only present a minor +20% bias in adherence, which can be attributed to the combination of a 10% increase in the average stress and a 10% increase in the maximum strain of the fibrils. This improvement in the understanding of the PSA performances opens the way to a more sound mechanical design of PSA based joints.

Improvements to an optical scintillator imaging-based tissue dosimetry system.

Previous work has shown that capturing optical emission from plastic discs attached directly to the skin can be a viable means to accurately measure surface dose during total skin electron therapy. This method can provide accurate dosimetric information rapidly and remotely without the need for postprocessing. The objective of this study was to: (1) improve the robustness and usability of the scintillators and (2) enhance sensitivity of the optical imaging system to improve scintillator emission detection as related to tissue surface dose. Baseline measurements of scintillator optical output were obtained by attaching the plastic discs to a flat tissue phantom and simultaneously irradiating and imaging them. Impact on underlying surface dose was evaluated by placing the discs on-top of the active element of an ionization chamber. A protective coating and adhesive backing were added to allow easier logistical use, and they were also subjected to disinfection procedures, while verifying that these changes did not affect the linearity of response with dose. The camera was modified such that the peak of detector quantum efficiency better overlapped with the emission spectra of the scintillating discs. Patient imaging was carried out and surface dose measurements were captured by the updated camera and compared to those produced by optically stimulated luminescence detectors (OSLD). The updated camera was able to measure surface dose with < 3 % difference compared to OSLD­Cherenkov emission from the patient was suppressed and scintillation detection was enhanced by 25 × and 7 × , respectively. Improved scintillators increase underlying surface dose on average by 5.2 ± 0.1 % and light output decreased by 2.6 ± 0.3 % . Disinfection had < 0.02 % change on scintillator light output. The enhanced sensitivity of the imaging system to scintillator optical emission spectrum can now enable a reduction in physical dimensions of the dosimeters without loss in ability to detect light output.

Microscopic colitis or functional bowel disease with diarrhea: a French prospective multicenter study.

OBJECTIVES: To describe the characteristics of a cohort of patients with microscopic colitis (MC; lymphocytic (LC) or collagenous (CC) colitis) and to compare them with patients with functional bowel disorder with diarrhea (FBD-D). METHODS: Between September 2010 and June 2012, patients fulfilling the following inclusion criteria were prospectively included in 26 centers in France: (i) having at least three bowel movements daily with change in stool consistency; (ii) duration of abnormal bowel habit >4 weeks; and (iii) normal or near-normal colonoscopy. Each patient underwent a colonoscopy and colonic biopsies. We compared the demographic, clinical, biological, and etiological characteristic of patients with MC (CC and LC) with those of control patients with FBD-D. RESULTS: A total of 433 patients were included: 129 with MC (87 LC and 42 CC), 23 with another organic disease, and 278 with FDB-D, including patients with diarrhea and abdominal pain who met the criteria of Rome III (irritable bowel syndrome with diarrhea) and patients with functional diarrhea without abdominal pain. Logistic regression analysis identified the following independent predictors of MC: age >50 years (odds ratio (OR)=3.1, 95% confidence interval (CI)=1.6-5.9), presence of nocturnal stools (OR=2, 95% CI=1.1-3.9), weight loss (OR=2.5, 95% CI=1.3-4.7), duration of diarrhea <12 months (OR=2.0, 95% CI=1.1-3.5), recent introduction of new drugs (OR=3.7, 95% CI=2.1-6.6; P<0.0001), and the presence of a known autoimmune disorder (OR=5.5, 95% CI=2.5-12). CONCLUSIONS: Age >50 years, the presence of nocturnal stools, weight loss, the introduction of a new drug, and the presence of a known autoimmune disease increase the probability of MC and thus the indication for colonoscopy with biopsies.

Origin and incidence of 2-methoxy-3,5-dimethylpyrazine, a compound with a "fungal" and "corky" aroma found in cork stoppers and oak chips in contact with wines.

This study identifies a previously isolated bacterium as Rhizobium excellensis, a new species of proteobacteria able to form a large quantity of 2-methoxy-3,5-dimethylpyrazine (MDMP). R. excellensis actively synthesizes MDMP from L-alanine and L-leucine and, to a lesser extent, from L-phenylalanine and L-valine. MDMP is a volatile, strong-smelling substance detected in wines with cork stoppers that have an unpleasant "corky", "herbaceous" (potato, green hazelnut), or "dusty" odor that is very different from the typical "fungal" nose of a "corked" wine that is generally due to 2,4,6-trichloroanisole (TCA). The contamination of cork by MDMP is not correlated with the presence of TCA. It appears possible that R. excellensis is the microorganism mainly responsible for the presence of this molecule in cork bark. However, other observations suggest that MDMP might taint wine through other ways. Oak wood can also be contaminated and affect wines with which it comes into contact. Nevertheless, because 93% of the MDMP content in wood is destroyed after 10 min at 220 °C, sufficiently toasted oak barrels or alternatives probably do not represent a major source of MDMP in most of the cases. Due to MDMP's relatively low detection threshold estimated at 2.1 ng/L, its presence in about 40% of the untreated natural cork stoppers sampled at concentrations above 10 ng/cork suggests that this compound, if extracted from the stoppers, may pose a risk for wine producers.

Identification of a new source of contamination of Quercus sp. oak wood by 2,4,6-trichloroanisole and its impact on the contamination of barrel-aged wines.

Thanks to practical experience in various wineries in recent years, it is now clear that, similarly to the well-known phenomenon in corks, there are several sources of unpredictable contamination of oak wood by 2,4,6-trichloroanisole (TCA). TCA affects staves in the same barrel very sporadically, with extremely limited contaminated areas on the surface that may reach several millimeters in depth. The precise origin of the TCP and TCA in oak wood is not known at this stage. Available data indicate that the phase where stavewood is naturally dried and seasoned is the source of these undesirable organochlorine contaminants. The strictly chemical formation of 2,4,6-trichlorophenol (TCP), derived from organochlorine biocides, was demonstrated to be impossible under traditional cooperage conditions, and its accumulation remained highly improbable. Similarly to previous discoveries in corks, all the analyses of oak wood suggested that the TCP was of biochemical origin. The capacity to biomethylate chlorophenols is well-known and relatively widespread among the usual microflora in stavewood, but the precise origin of the intermediary leading to TCP formation is still unknown. One probable hypothesis is that this reaction involves chloroperoxidase (CPO). Several ideas have been proposed, but the microorganisms responsible for the formation of the TCA precursor in oak wood have not yet been identified. The extent of this problem is still severely underestimated by coopers and barrel-users, due to the extremely unpredictable, localized contamination of the staves.

Socioeconomic deprivation does not influence the severity of Crohn's disease: Results of a prospective multicenter study.

BACKGROUND: Socioeconomic deprivation is associated with poor health. The aims of this study were to evaluate the influence of deprivation in the characteristics and comparisons of deprived and nondeprived Crohn's disease (CD) patients. METHODS: CD patients were prospectively recruited from September 2006 to June 2007 in 6 hospitals in the Paris area. To assess the level of deprivation we used the EPICES score (Evaluation of Precarity and Inequalities in Health Examination Centers; http://www.cetaf.asso.fr), a validated individual index of deprivation developed in France, a score >30 defining deprivation. We defined CD as severe when at least 1 of the conventionally predefined criteria of clinical severity was present. RESULTS: In all, 207 patients (128 women and 79 men, mean age 40 years) were included and had a median score of deprivation of 20.7 (0-100). Seventy-three (35%) were deprived. There were no statistical differences between deprived and nondeprived patients for the following parameters: 1) mean age: 39 +/- 14.6 versus 40.6 +/- 13.5, P = 0.4; 2) sex ratio (female/male): 87/47 (65%) versus 41/32 (56%), P = 0.2; 3) duration of disease (years) 9 +/- 8.8 versus 8.5 +/- 7.2, P = 0.7; 4) delay from onset of symptoms to diagnosis >1 year: 22/115 (19%) versus 13/63 (21%), P = 0.8; and 5) severity of disease 71% versus 70% (P = 0.9). Nondeprived patients had a lower rate of hospitalization (40 versus 56%, P = 0,04) and a higher rate of surgery (44 versus 22%, P = 0,004); the rate of surgery was only identified by logistic regression. CONCLUSIONS: In this study deprivation does not seem to influence the severity of CD. This can be explained by easy access to healthcare in France.