Redox-active electrolyte for supercapacitor application.

This paper reports the electrochemical behaviour of supercapacitor carbon electrodes operating in different aqueous solutions modified by various redox-active species (hydroxybenzenes, bromine derivatives and iodide). Three dihydroxybenzenes with varying stereochemistry, i.e., -OH substitution, have been considered as electrolyte additives (0.38 mol L(-1)) in acidic, alkaline and neutral solutions. High capacitance values have been obtained, especially for the acidic and alkaline solutions containing 1,4-dihydroxybenzene (hydroquinone). Bromine derivatives of dihydroxybenzenes were also considered as the additive in alkaline solution for use as a supercapacitor electrolyte, and a significant increase in capacitance value was observed. The redox couple investigated next was an iodide/iodine system, where 2 mol L(-1) NaI aqueous electrolyte was utilized. In this case, the most promising faradaic contribution during capacitor operation was achieved. In particular, stable capacitance values from 300-400 F g(-1) have been confirmed by long-term galvanostatic cycling (over 100 000 cycles), cycling voltammetry and floating. The mechanism of pseudocapacitance phenomena was discussed and supported by electrochemical and physicochemical measurements, e.g., in situ Raman spectroscopy.

Neurodegeneration of the retina in type 1 diabetic patients.

INTRODUCTION: The degeneration of retinal neurons and glial cells has recently been postulated in the pathogenesis of diabetic retinopathy. Optical coherence tomography (OCT) allows to perform qualitative and quantitative measurements of retinal thickness (RT) with identification of individual retinal layers. OBJECTIVES: We compared RT, retinal nerve fiber layer (RNFL) thickness, and ganglion cell layer (GCL) thickness obtained by OCT in type 1 diabetic patients with and without clinically diagnosed retinopathy. PATIENTS AND METHODS: The study included 77 consecutive patients with type 1 diabetes (39 men, 38 women; median age, 35 years [interquartile range (IQR), 29-42]; median disease duration, 10 years [IQR, 9-14]) and 31 age- and sex-matched controls. We measured RT in the fovea, parafovea, and perifovea, as well as RNFL and GCL thickness. We divided diabetic patients into 2 subgroups, i.e., those with diabetic retinopathy and without retinopathy. RESULTS: We observed thicker perifoveal retina (P = 0.05), mean RNFL (P = 0.002), inferior RNFL (P <0.0001), and superior and inferior GCL (P = 0.05 and P = 0.04, respectively) in diabetic subjects compared with the control group. We detected retinopathy in 23 diabetic patients (29%). Compared with patients without retinopathy, subjects with retinopathy had thinner parafoveal retina (P = 0.05), mean RNFL (P = 0.002), inferior and nasal RNFL (P = 0.002, P = 0.03), superior (P = 0.05) and inferior GCL (P = 0.006). Significant correlations were found between duration of diabetes and nasal RNFL thickness (r = -0.32, P = 0.004) and parafoveal RT (r = -0.47, P <0.001). CONCLUSIONS: The results might suggest the loss of intraretinal neural tissue in type 1 diabetic patients with retinopathy. Neurodegeneration in diabetic retinopathy is closly associated with disease duration.

Electrochemistry serving people and nature: high-energy ecocapacitors based on redox-active electrolytes.

Positive Poles: A new type of electrochemical capacitor with two different aqueous solutions, separated by a Nafion membrane is described. High capacitance values as well as excellent energy/power characteristics are reported and discussed. The neutral character of the applied electrolytes makes this capacitor an environmentally friendly, easy to assemble, and cost-effective device for energy storage.