Ab initio structure search and in situ 7Li NMR studies of discharge products in the Li-S battery system.

The high theoretical gravimetric capacity of the Li-S battery system makes it an attractive candidate for numerous energy storage applications. In practice, cell performance is plagued by low practical capacity and poor cycling. In an effort to explore the mechanism of the discharge with the goal of better understanding performance, we examine the Li-S phase diagram using computational techniques and complement this with an in situ (7)Li NMR study of the cell during discharge. Both the computational and experimental studies are consistent with the suggestion that the only solid product formed in the cell is Li2S, formed soon after cell discharge is initiated. In situ NMR spectroscopy also allows the direct observation of soluble Li(+)-species during cell discharge; species that are known to be highly detrimental to capacity retention. We suggest that during the first discharge plateau, S is reduced to soluble polysulfide species concurrently with the formation of a solid component (Li2S) which forms near the beginning of the first plateau, in the cell configuration studied here. The NMR data suggest that the second plateau is defined by the reduction of the residual soluble species to solid product (Li2S). A ternary diagram is presented to rationalize the phases observed with NMR during the discharge pathway and provide thermodynamic underpinnings for the shape of the discharge profile as a function of cell composition.Fellowship support to KAS from the ConvEne IGERT Program of the National Science Foundation (DGE 0801627) is gratefully acknowledged. AJM acknowledges the support from the Winton Programme for the Physics of Sus-tainability. PDM and DSW thank the UK-EPSRC for financial support. This research made use of the shared experimental facilities of the Materials Research Laboratory (MRL), sup-ported by the MRSEC Program of the NSF under Award No. DMR 1121053. The MRL is a member of the NSF-funded Mate-rials Research Facilities Network (www.mrfn.org). CPG and ML thank the U.S. DOE Office of Vehicle Technologies (Con-tract No. DE-AC02-05CH11231) and the EU ERC (via an Ad-vanced Fellowship to CPG) for funding.This is the final published version. It first appeared at http://pubs.acs.org/doi/abs/10.1021/ja508982p

Physical therapy combined with a laxative fruit drink for treatment of chagasic megacolon

CONTEXT: The treatment of Chagas' disease colopathy is limited to clinical management in the initial of the process, and for patients for whom surgery is not indicated or is not possible, anti-constipation diets are used, along with judicious administration of laxatives and enemas. OBJECTIVE: To evaluate over time the effects of physical-therapy interventions combined with daily ingestion of a laxative fruit drink in the treatment of chagasic megacolon. METHOD: In a quantitative, prospective, and comparative study, 12 patients of both sexes and with a mean age of 67 ± 12 years were clinically evaluated to receive 12 sessions of physical therapy twice a week, along with fruit drink, and were evaluated for intestinal constipation before and after treatment. RESULTS: A significant difference (P<0.0022) was observed in the constipation scores before and after 6 weeks of intervention in 91.7% of the patients, and in 72.7% after 12 months, with reduction of laxative medications, softer stools, and increased number of bowel movements. With respect to gender, age, and whether or not the patient had received surgical treatment, there was no significant difference (P>0.05). CONCLUSION: The proposed protocol is easy to implement, safe, non-invasive, and low-cost, with the potential to be deployed in health care by providing benefits independent of gender, age, or whether the participant has undergone surgery, improving the condition of patients with chagasic megacolon

Ab Initio Structure Search and in Situ ⁷Li NMR Studies of Discharge Products in the Li–S Battery System

The high theoretical gravimetric capacity of the Li–S battery system makes it an attractive candidate for numerous energy storage applications. In practice, cell performance is plagued by low practical capacity and poor cycling. In an effort to explore the mechanism of the discharge with the goal of better understanding performance, we examine the Li–S phase diagram using computational techniques and complement this with an in situ ⁷Li NMR study of the cell during discharge. Both the computational and experimental studies are consistent with the suggestion that the only solid product formed in the cell is Li₂S, formed soon after cell discharge is initiated. In situ NMR spectroscopy also allows the direct observation of soluble Li⁺-species during cell discharge; species that are known to be highly detrimental to capacity retention. We suggest that during the first discharge plateau, S is reduced to soluble polysulfide species concurrently with the formation of a solid component (Li₂S) which forms near the beginning of the first plateau, in the cell configuration studied here. The NMR data suggest that the second plateau is defined by the reduction of the residual soluble species to solid product (Li₂S). A ternary diagram is presented to rationalize the phases observed with NMR during the discharge pathway and provide thermodynamic underpinnings for the shape of the discharge profile as a function of cell composition