Role of solvent-anion charge transfer in oxidative degradation of battery electrolytes

Electrochemical stability windows of electrolytes largely determine the limitations of operating regimes of lithium-ion batteries, but the degradation mechanisms are difficult to characterize and poorly understood. Using computational quantum chemistry to investigate the oxidative decomposition that govern voltage stability of multi-component organic electrolytes, we find that electrolyte decomposition is a process involving the solvent and the salt anion and requires explicit treatment of their coupling. We find that the ionization potential of the solvent-anion system is often lower than that of the isolated solvent or the anion. This mutual weakening effect is explained by the formation of the anion-solvent charge-transfer complex, which we study for 16 anion-solvent combinations. This understanding of the oxidation mechanism allows the formulation of a simple predictive model that explains experimentally observed trends in the onset voltages of degradation of electrolytes near the cathode. This model opens opportunities for rapid rational design of stable electrolytes for high-energy batteries

Homochirality and the need of energy

The mechanisms for explaining how a stable asymmetric chemical system can be formed from a symmetric chemical system, in the absence of any asymmetric influence other than statistical fluctuations, have been developed during the last decades, focusing on the non-linear kinetic aspects. Besides the absolute necessity of self-amplification processes, the importance of energetic aspects is often underestimated. Going down to the most fundamental aspects, the distinction between a single object -- that can be intrinsically asymmetric -- and a collection of objects -- whose racemic state is the more stable one -- must be emphasized. A system of strongly interacting objects can be described as one single object retaining its individuality and a single asymmetry; weakly or non-interacting objects keep their own individuality, and are prone to racemize towards the equilibrium state. In the presence of energy fluxes, systems can be maintained in an asymmetric non-equilibrium steady-state. Such dynamical systems can retain their asymmetry for times longer than their racemization time.Comment: 8 pages, 7 figures, submitted to Origins of Life and Evolution of Biosphere

Neuropsychological intervention in kindergarten children with subtyped risks of reading retardation

Kindergarten children at risk of developing language problems were administered the Florida Kindergarten Screening Battery. A principal components analysis revealed a verbal and a visual-spatial component and subsequent discriminant function analyses a high verbal/low visual-spatial group (LAL: Latent L) and a high visual-spatial/low verbal group (LAP: Latent P). LAL- and LAP-children were considered at risk for developing an L- or P-type of dyslexia, respectively. As is common practice with children suffering from manifest L- or Pdyslexia, the LAL- and LAP-kindergartners received right and left hemisphere stimulation, respectively. The outcomes were compared with those of bilateral hemispheric stimulation and no intervention. Reading tests were administered in primary school Grades 1 and 5/6; teachers' evaluation of reading took place in Grade 5/6. Overall, the LAL- and LAP- groups showed significant backwardness in word and text reading, both at early and late primary school. Types of intervention made a difference though: not significantly backward in early word, late word, and late text reading were the LAL-children who had received right hemisphere stimulation. Nonintervened LAP-children did not show significant backwardness in early word reading and late text reading, nor did LAP-children who had received left hemisphere or bilateral stimulation. Early text reading was not affected by any treatment. Teacher's evaluations were in support of these findings. Copyright © 2005 by The International Dyslexia Association®

Neuropsychological patterns following lesions of the anterior insula in a series of forty neurosurgical patients

In the present study we investigated the effects of lesions affecting mainly the anterior insula in a series of 22 patients with lesions in the left hemisphere (LH), and 18 patients with lesions involving the right hemisphere (RH). The site of the lesion was established by performing an overlap of the probabilistic cytoarchitectonic maps of the posterior insula. Here we report the patients\u2019 neuropsychological profile and an analysis of their pre-surgical symptoms. We found that pre-operatory symptoms significantly differed in patients depending on whether the lesion affected the right or left insula and a strict parallelism between the patterns emerged in the pre-surgery symptoms analysis, and the patients\u2019 cognitive profile. In particular, we found that LH patients showed cognitive deficits. By contrast, the RH patients, with the exception of one case showing an impaired performance at the visuo-spatial planning test were within the normal range in performing all the tests. In addition, a sub-group of patients underwent to the post-surgery follow-up examination

Epidemiology of amyotrophic lateral sclerosis in the province of Modena, Italy, years 1990-1999

Monetary instruments to regulate parking are often used in central areas of cities to discourage long term parking of vehicles. The availability of parking facilities, and its cost, in fact represents an important element in the decision to operate private vehicles in urban areas. The availability of instruments and tools to check the outcome of modification in parking regulations, in terms of modification of car use, successfully support planners in the determination of the best policies to decrease congestion, and regulate the use of transportation in cities. Integrated land use transportation models may successfully contribute to the assessment of such policy packages. This contribution discusses the use of the model MARS-Bari (Metropolitan Activity Relocation Simulator) for the analysis of future scenarios of development of land use and transportation. MARS-Bari is a fast integrated land use transportation model, which is designed for applications in strategic planning of urban and metropolitan areas. The model was developed as a decision support tool, to help planners in the definition of sets of policies on land use and transportation, and promote equilibrated growth of the urban system (smart growth). MARS-Bari shares the basic assumptions of the Metropolitan Activity Relocation Simulator (MARS) modeling system, so far successfully applied to many cities of both Europe and Asia. The structure of MARS-Bari is highly flexible on purpose, allowing multiple hypothesis tests of future scenarios and policies. MARS-Bari works at a high level of spatial aggregation, and its simulations are developed on a long-term time horizon (30-years in the current version). Two main sub-models run in MARS-Bari: they respectively simulate the development of land use, and the transportation system. Four different classes of users are distinguished in the transportation model, depending on the possible access to one or more of the five transportation modes: car, motorcycle, bus, train, and slow mode (walk and bike). Car and motorcycle ownership and availability functions contribute to the definition of travel patterns and activity participation of users, in dependence of the chosen residential location and of the location of the economic activities. The model was implemented and tested on the metropolitan area of Bari, Italy. MARS-Bari allows the evaluation of different scenarios of future development of the area, predicting the expected outcomes of policies and interventions on land use development, transportation infrastructures, modifications in the local economy, financial regulations and fares (e.g. fuel price, road pricing, congestion charge, parking fares, etc.). The estimation of indicators for environmental quality and pollutant emissions from transportation permits the direct comparison of the outcomes of different scenarios, thus supporting the definition of sets of “second-best” choices for policies in both land use and transportation planning