Water in a Polymeric Electrolyte Membrane: Sorption/Desorption and Freezing phenomena

Nafion is a perfluorosulfonated polymer, widely used in Proton Exchange Membrane Fuel Cells. This polymer adopts a complex structural organisation resulting from the microsegregation between hydrophobic backbones and hydrophilic sulfonic acid groups. Upon hydration appear water-filled channels and cavities, in which are released the acidic protons to form a solution of hydronium ions in water embedded in the polymer matrix. Below 273 K, a phenomenon of water sorption/desorption occurs, whose origin is still an open question. Performing neutron diffraction, we monitored the quantity of ice formed during the sorption/desorption as a function of temperature down to 180 K. Upon cooling, we observe that ice forms outside of the membrane and crystallises in the hexagonal Ih form. Simultaneously, the membrane shrinks and dehydrate, leading to an increase of the hydronium ions concentration inside the matrix. Reversibly, the ice melts and the membrane re-hydrate upon heating. A model of solution, whose freezing point varies with the hydronium concentration, is proposed to calculate the quantity of ice formed as a function of temperature. The quantitative agreement between the model and experimental data explains the smooth and reversible behavior observed during the sorption or desorption of water, pointing out the origin of the phenomena. The proposed picture reconciles both confinement and entropic effects. Other examples of water filled electrolyte nano-structures are eventually discussed, in the context of clarifying the conditions for water transport at low temperature

Operative and nonoperative management for renal trauma. Comparison of outcomes. A systematic review and meta-analysis

INTRODUCTION: Preservation of kidney and renal function is the goal of nonoperative management (NOM) of renal trauma (RT). The advantages of NOM for minor blunt RT have already been clearly described, but its value for major blunt and penetrating RT is still under debate. We present a systematic review and meta-analysis on NOM for RT, which was compared with the operative management (OM) with respect to mortality, morbidity, and length of hospital stay (LOS). METHODS: The Preferred Reporting Items for Systematic Reviews and Meta-analyses statement was followed for this study. A systematic search was performed on Embase, Medline, Cochrane, and PubMed for studies published up to December 2015, without language restrictions, which compared NOM versus OM for renal injuries. RESULTS: Twenty nonrandomized retrospective cohort studies comprising 13,824 patients with blunt (2,998) or penetrating (10,826) RT were identified. When all RT were considered (American Association for the Surgery of Trauma grades 1-5), NOM was associated with lower mortality and morbidity rates compared to OM (8.3% vs 17.1%, odds ratio [OR] 0.471; 95% confidence interval [CI] 0.404-0.548; P<0.001 and 2% vs 53.3%, OR 0.0484; 95% CI 0.0279-0.0839, P<0.001). Likewise, NOM represented the gold standard treatment resulting in a lower mortality rate compared to OM even when only high-grade RT was considered (9.1% vs 17.9%, OR 0.332; 95% CI 0.155-0.708; P=0.004), be they blunt (4.1% vs 8.1%, OR 0.275; 95% CI 0.0957-0.788; P=0.016) or penetrating (9.1% vs 18.1%, OR 0.468; 95% CI 0.398-0.0552; P<0.001). CONCLUSION: Our meta-analysis demonstrated that NOM for RT is the treatment of choice not only for AAST grades 1 and 2, but also for higher grade blunt and penetrating RT

The Role of Rac1 in the Growth Cone Dynamics and Force Generation of DRG Neurons

We used optical tweezers, video imaging, immunocytochemistry and a variety of inhibitors to analyze the role of Rac1 in the motility and force generation of lamellipodia and filopodia from developing growth cones of isolated Dorsal Root Ganglia neurons. When the activity of Rac1 was inhibited by the drug EHop-016, the period of lamellipodia protrusion/retraction cycles increased and the lamellipodia retrograde flow rate decreased; moreover, the axial force exerted by lamellipodia was reduced dramatically. Inhibition of Arp2/3 by a moderate amount of the drug CK-548 caused a transient retraction of lamellipodia followed by a complete recovery of their usual motility. This recovery was abolished by the concomitant inhibition of Rac1. The filopodia length increased upon inhibition of both Rac1 and Arp2/3, but the speed of filopodia protrusion increased when Rac1 was inhibited and decreased instead when Arp2/3 was inhibited. These results suggest that Rac1 acts as a switch that activates upon inhibition of Arp2/3. Rac1 also controls the filopodia dynamics necessary to explore the environment

Socioeconomic deprivation status and air pollution by PM10 and NO2: an assessment at municipal level of 11 years in Italy

The aim of this observational study was to assess the relationship between environmental risk factors and some aspects of social economic status (SES) of the population in different Italian municipalities. Nitrogen dioxide (NO2) and particulate matter (PM10) annual means were extracted from ISPRA-BRACE (environmental information system of 483 Italian municipalities, 6% of the total amount of administrative units) from 2002 to 2012. As an indicator of sociodemographic and SES data, we collected the following: resident population, foreign nationality, low level of education, unemployment, nonhome ownership, single-parent family, and overcrowding. Low educational level, unemployment, and lack of home ownership were indirectly associated with the higher mean values of NO2 at the statistically significant level (). Major resident population and rental housing percentage determined higher levels of PM10. Northern regions showed similar results compared to the national level, with the exception of foreign residency that showed direct correlation with the increase of PM10. The central regions showed a direct relationship between NO2 and PM10 levels and higher educational levels and between NO2 levels and percentage of single-parent family. In the southern areas, higher NO2 levels were correlated with a higher rental housing percentage, as well as higher PM10 levels with a higher percentage of unemployment and lower housing density. The study shows high heterogeneity in the findings but confirms the relationship between high educational level and employment with the increased concentration of pollutants. The higher rental housing percentage may increase the pollutants’ levels too. The housing density does not seem to be in relationship with NO2 and PM10 at the national level. The analysis stratified by geographical areas showed that the direction of the correlations was different over time as the analysis was at a national level. The study represents an example of how data from national information systems can provide a preliminary evaluation and be a comparative tool for policy-makers to assess environmental risk factors and social inequalities

Suspensory materials for surgery of blepharoptosis: a systematic review of observational studies

Background Frontalis suspension surgery is considered the procedure of choice in cases of blepharoptosis. Among all the materials used in this type of surgery, ophthalmic and plastic surgeons prefer to use autologous Fascia Lata. However, during years, other autogenous and exogenous materials have been introduced. Objectives The aim of this study was therefore that of systematically reviewing the functional results and the rate of complications of different synthetic materials, as compared to autogenous Fascia Lata. The primary objective was to determine the rates of Successful Surgeries (SSs) of these materials. The secondary objective was to assess the onset of complications. The following materials were investigated: Fascia Lata, Mersilene, polytetrafluoroethylene (PTFE) and Silicon. Data Source and Methods Following the Prisma procedure, on January 30th, 2016 we used the following electronic databases to select the studies: MEDLINE and Scopus. Results The search strategy retrieved 48 publications that met the eligibility criteria of the systematic review. All studies were non-comparative. PTFE (n = 5) showed the best rate of SSs among the materials compared (statistically significant). Surgeries performed with autogenous Fascia Lata (n = 19) had a 87% rate of success those performed with Mersilene (n = 12)had 92% and those performed with Silicon (n = 17)88%. PTFE had the best outcome, with 99% success rate. As for complications, surgeries performed with PTFE had a higher rate of suture infections (1.9%) as compared to Fascia Lata, but lower incidence for all other complications. Conclusions Although most studies were good quality cohort studies, the overall quality of this evidence should be regarded as low due to their non-comparative design. Our data suggest that PTFE seems to be the most valid alternative material for frontalis suspension surgery, with low recurrence rates and good cosmetic and functional results