Na2Ti3O7 Nanoplatelets and Nanosheets Derived from a Modified Exfoliation Process for Use as a High-Capacity Sodium-Ion Negative Electrode.

The increasing interest in Na-ion batteries (NIBs) can be traced to sodium abundance, its low cost compared to lithium, and its intercalation chemistry being similar to that of lithium. We report that the electrochemical properties of a promising negative electrode material, Na2Ti3O7, are improved by exfoliating its layered structure and forming 2D nanoscale morphologies, nanoplatelets, and nanosheets. Exfoliation of Na2Ti3O7 was carried out by controlling the amount of proton exchange for Na+ and then proceeding with the intercalation of larger cations such as methylammonium and propylammonium. An optimized mixture of nanoplatelets and nanosheets exhibited the best electrochemical performance in terms of high capacities in the range of 100-150 mA h g-1 at high rates with stable cycling over several hundred cycles. These properties far exceed those of the corresponding bulk material, which is characterized by slow charge-storage kinetics and poor long-term stability. The results reported in this study demonstrate that charge-storage processes directed at 2D morphologies of surfaces and few layers of sheets are an exciting direction for improving the energy and power density of electrode materials for NIBs.

High performance pseudocapacitor based on 2D layered metal chalcogenide nanocrystals.

Single-layer and few-layer transition metal dichalcogenides have been extensively studied for their electronic properties, but their energy-storage potential has not been well explored. This paper describes the structural and electrochemical properties of few-layer TiS2 nanocrystals. The two-dimensional morphology leads to very different behavior, compared to corresponding bulk materials. Only small structural changes occur during lithiation/delithiation and charge storage characteristics are consistent with intercalation pseudocapacitance, leading to materials that exhibit both high energy and power density.

Discussion on a percolating conducting network of a composite thin-film electrode (≤1 µm) for micro-solid oxide fuel cell application.

Ni/Gd0.1Ce0.9O(2-δ) (Ni/GDC) and La0.6Sr0.4Fe0.8Co0.2O(3-δ)/Gd0.1Ce0.9O(2-δ) (LSCF/GDC) porous thin-film electrodes with thicknesses between 120 and 500 nm were synthesized through templated sol-gel chemistry coupled with the dip-coating process and heat treatment. The thin films consist of two interpenetrated networks made of pores and inorganic materials. The porous structure was composed of multi-scale pores with dimensions ranging from macro- to nanosize and with an oriented columnar structure. The dimension of the percolation network is discussed as a function of the chemical nature of the percolating components and the particle/thickness ratio. A three-dimensional percolation network is achieved in the LSCF/GDC composite, while a two-dimensional percolation network is observed for the Ni/GDC composite. This difference is related to the microstructure of the composite thin film. An anisotropic columnar structure is observed for Ni/GDC, while an isotropic structure is achieved for LSCF/GDC.

Overall mortality after radical nephrectomy in patients aged over 80 years with renal cancer: a retrospective study on preoperative prognostic factors.

OBJECTIVES: To evaluate the overall survival postnephrectomy for renal cancer for patients aged over 80 years, and to identify preoperative prognostic factors that might influence therapeutic strategies. METHODS: In a retrospective study in five French departments of urology, 179 patients aged over 80 years with renal cell carcinoma underwent radical nephrectomy between 1990 and 2011. The following data were collected: age, sex, body mass index, Charlson Comorbidity Index, American Society of Anesthesiology class, Eastern Cooperative Oncology Group Performance Status, type of surgery, period of follow-up, survival, death etiology, symptoms, Fuhrman grade and tumor-nodes-metastasis stage. RESULTS: After a 29.6-month follow up, 89 patients (49.7%) died. Death etiologies were: cancer for 46 (52%) patients, immediate or distant perioperative complications for five patients (6%) and three patients (3%) respectively, cardiovascular disease for 16 patients (18%), other cancers for three patients (3%) and unknown for 16 patients (18%). In a multivariate analysis, T-stage, M-stage and Charlson Comorbidity Index were identified as independent prognostic factors. Patients were divided into three groups (good, intermediate and bad prognosis) with significantly different survivals of 91, 36 and 22 months (P < 0.0001), respectively. CONCLUSIONS: Preoperative data, including T-stage, M-stage and Charlson Comorbidity Index represent significant independent prognostic factors for survival for patients aged over 80 years. These data might help the clinician in selecting the most suitable candidates for radical nephrectomy among elderly patients with renal cancer.

An agent-based model of sleeping sickness: simulation trials of a forest focus in southern Cameroon.

An agent-based model (AMB) used to simulate the spread of Human African Trypanosomiasis is presented together with the results of simulations of a focus of the disease. This model is a completely spatialized approach taking into account a series of often overlooked parameters such as human behaviour (activity-related movements), the density and mobility of the disease vectors--tsetse flies (Glossina spp.)--and the influence of other tsetse feeding hosts (livestock and wild animal populations). The agents that represent humans and tsetse flies move in a spatially structured environment managed by specialized location agents. Existing compartmental mathematical models governed by differential equations fail to incorporate the spatial dimension of the disease transmission. Furthermore, on a small scale, transmission is unrealistically represented by entities less than one. This ABM was tested with data from one village of the Bipindi sleeping sickness focus (southern Cameroon) and with obtained realistic simulations of stable transmission involving an animal reservoir. In varying different spatial configurations, we observe that the stability of spread is linked to the spatial complexity (number of heterogeneous locations). The prevalence is very sensitive to the human densities and to the number of tsetse flies initially infected in a given location. A relatively low and durable prevalence is obtained with shortening the phase I. In addition, we discuss some upgrading possibilities, in particular the linkage to a Geographical Information System (GIS). The agent-based approach offers new ways to understanding the spread of the disease and a tool to evaluate risk and test control strategies.