Li-S batteries: Simple approaches for superior performance

Although promising improvements have been made in the field of Li-S rechargeable batteries, they are still far from reaching the market place due to several drawbacks. To combat the solubility of polysulphides, confinement approaches aiming to trap sulphur within the cathode side have been pursued, but success has been limited. Herein, we drastically deviate from this approach and use a liquid cathode obtained either by dissolving polysulphides within the electrolyte or by placing sulphur powders in contact with the Li negative electrode. Such approaches are shown to result in greater performance than confinement approaches. Such a strategy eliminates the detrimental Li 2S formation inside a porous carbon matrix and moreover leads to the formation of a protective SEI layer at the Li electrode, as deduced by impedance spectroscopy and XPS, which seems beneficial to the cell cycling performance. © The Royal Society of Chemistry 2013

Prevalence and factors associated to back pain in adults from the northeast of São Paulo, Brazil: a population-based study

Abstract Introduction: Back pain has become a serious public health problem. Objective: To determine the prevalence of back pain in a population-based sample of subjects over 20 years old living in the city of Bauru (São Paulo, Brazil) and to analyze the associations to variables- sociodemographic, ergonomic and lifestyle-related - and to morbidity. Methods: a cross-sectional study which evaluated 600 adults over 20 years old, both gender and living in the city. We used a structured protocol and the Nordic questionnaire. Also, we developed a descriptive analysis, bivariate and multivariate by binary logistic regression. Results: The prevalence of back pain was of 50.3% (CI 46.3 to 54.3), since 42.3% (CI 36.9 to 48.0) in men and 57.6% (CI 51.9 to 63.0) in women, with statistical significant difference (p = 0.001). Different variables remained in final models when assessed by gender. For male to be widowed and divorced and smoking habits and, for women to be widowed and divorced, to work in seated position and to perform occupational activities that demand carrying and lifting weight. Conclusion: We verified high prevalence in back pain in the population of Bauru and high association to widowed/divorced in both gender, with women performing occupational activities usually or always in seated position, those who carry or lift weight in work and men who smoke