An Electrochemical cell for <i>in operando</i> ¹³C NMR investigations of carbon dioxide/carbonate processes in aqueous solution

In operando NMR spectroscopy is a method for the online investigation of electrochemical systems and reactions. It allows a real-time observation of the formation of products and intermediates, and it grants insight into the interactions of substrate and catalyst. An in operando NMR setup for the investigation of the electrolytic reduction of CO2 on silver electrodes has been developed. The electrolysis cell consists of a three-electrode setup using a working electrode of pristine silver, a chlorinated silver wire as reference electrode, and a graphite counter electrode. The setup can be adjusted for the use of different electrode materials and fits inside a 5 mm NMR tube, Additionally, a shielding setup was employed to minimize noise caused by interference of external radio frequency (RF) waves with the conductive components of the setup. The electrochemical performance of the in operando electrolysis setup was investigated in comparison to a standard CO2 electrolysis cell. The small cell geometry impedes the release of gaseous products, and thus it is primarily suited for current densities below 1 mA/cm2. The effect of conductive components on 13C NMR experiments was studied using a CO2 saturated solution of aqueous bicarbonate electrolyte. Despite the B0 field distortions caused by the electrodes, line widths of ca. 1 Hz could be achieved. This enables the investigation of interactions in the sub-Hertz range by NMR spectroscopy. It was found that the dynamics of the bicarbonate electrolyte change due to interaction with the electrochemical setup, by catalyzing the exchange reaction between CO2 and HCO3− and affecting the formation of an electrical double layer.

Different Finite Element Software on Electric Field Analysis of Magnesium Electrolysis Cell

The electric field distribution was the main factor affecting on the current efficiency of electrolysis cell. So, the electric field distribution of magnesium electrolysis cell was studied to improve the current efficiency by two of main finite element softwares, COMSOL and ANSYS. The electric field distribution and its trends with the electrolyte change from 1.25m to 1.40m were calculated by using the two softwares. Form the results, the characteristics of COMSOL and ANSYS can be obtained. The conclusions of the paper will provided a significant reference for choose the appropriate software in practice process.

Nocturia: a blinded, randomized, parallel placebo-controlled self-study of the effect of 5 different sedatives and analgesics

Background: In a previous study I noted that, when taken occasionally as a nighttime sedative, the benzodiazepine (BZD) oxazepam decreased nocturia. The objective of the present study was, using placebo and other sedatives and analgesics, to assess whether oxazepam decreases nocturia and, if so, how?Methods: I conducted a prospective, randomized, placebo-controlled self-study over a period of 10 months using oxazepam, zopiclone and trazodone as sedatives, and naproxen and oxycodone as analgesics. I assessed each medication 10 times, for a total of 60 tests. Each test included assessment of sleep adequacy, number and volume of overnight voidings and chemistries. Every test was a “first-time” or “naive” event.Results: All medications differed in several parameters from placebo, but nocturia only showed a significant reduction with naproxen and oxazepam. Nocturia occurred a mean (standard deviation [SD]) of 1.6 (0.84) times nightly with placebo and fell to 0.6 (0.5) with oxazepam, which was a 63% decrease without any change in urine volume. Naproxen reduced nocturia to a mean (SD) of 0.7 (0.8) times nightly by reducing water, salt and potassium excretion. Compared with placebo, all medications had less urine sodium loss and decreased fractional sodium excretion (FENa), suggesting increased renal tubular sodium reabsorption. This effect was most marked with naproxen. Neither improved sleep quality with zopiclone nor pain relief with oxycodone resulted in reduced nocturia.Conclusion: The effect of naproxen was probably a direct one on the kidney. The reduction of electrolyte excretion produced by the other medications is possibly a central effect on sympathetic activity, and the effect was too small to change urine volume. The effect of oxazepam was to make the bladder less irritable and could not be attributed to a decrease in urine volume, electrolyte change, sedation or analgesia. A central γ-aminobutyric acid–mediated effect in the cord or brain could explain the results observed with oxazepam.