Structure effect on the oxygen permeation properties of barium bismuth iron oxide membranes

In this work, we investigated the oxygen permeation properties of barium bismuth iron oxide within the family of [Ba_2−3xBi_3x−1][Fe_2xBi_1−2x]O_2+3x/2 for x = 0.17–0.60. The structure changed progressively from cubic to tetragonal and then to hexagonal as function of x in accordance with the different relative amounts of bismuth on A-site and B-site of ABO_3−δ perovskite lattices. We found that the oxygen flux and electrical conductivity correlated strongly, and it was prevalent for the cubic structure (x = 0.33–0.40) which conferred the highest oxygen flux of 0.59 ml min⁻¹ cm⁻² at 950 °C for a disk membrane x = 0.33 with a thickness of 1.2 mm. By reducing the thickness of the disk membrane to 0.8 mm, the oxygen flux increased to 0.77 ml min⁻¹ cm⁻², suggesting both surface kinetics and ion diffusion controlled oxygen flux, though the former was more prominent at higher temperatures. For disk membranes x = 0.45–0.60, the perovskite structure changed to tetragonal and hexagonal, and the oxygen flux was insignificant below 900 °C, clearly indicating electron conduction properties only. However, for two compositions with relatively high bismuth content, e.g. x = 0.55 and 0.60, there was a sudden and significant rise of oxygen permeability above 900 °C, by more than one order of magnitude. These materials changed conduction behavior from metallic to semiconductor at around 900 °C. These results suggest the advent of mixed ionic electronic conducting properties caused by the structure transition as bismuth ions changed their valence states to compensate for the oxygen vacancies formed within the perovskite lattices.

On-site determination of Pb2+ and Cd2+ in seawater by double stripping voltammetry with bismuth-modified working electrodes

To meet the urgent requirement of determining trace Pb2+ and Cd2+ in seawater on site, herein we developed a simple but novel electrochemical method, named as double stripping voltammetry, using only a portable heavy metal analyzer. The proposed method consisted of three steps: First, the targeted heavy metal ions in bulk solution were concentrated onto an ionic liquid-graphite-based paste working electrode (ILGPE), which exhibits a dramatic ability of accumulation, by electrodeposition in the presence of Bi3+. Second, the three-electrode arrangement, including the ILGPE loaded with the reduced products, was transferred into 1.0mL acetate buffer solution, followed by a stripping procedure. Third, the measurement was performed with the other stripping voltammetry procedure by using a glassy carbon electrode as working electrode. Under optimum conditions, the linear range values for Pb2+ and Cd2+ in seawater were 0.2-3.2 μg/L and 0.1-3.2 μg/L, respectively. The concentrations of Pb2+ and Cd2+ in five real samples collected from coastal sites of Qingdao City were determined on site, and the results were in good agreement with that obtained with the atomic absorption spectroscopy method. In addition, the analytical performance of working electrode modified with Bi film by in situ mode was investigated in comparison with that by ex situ mode. The results showed that the in situ mode was much better than the ex situ one.

A randomized comparison of quadruple and triple therapies for helicobacter pylori eradication: The QUADRATE study.

Background & Aims: Direct comparisons of bismuth and proton pump inhibitor (PPI)-based triple and quadruple therapies for Helicobacter pylori eradication are lacking. To address this, a randomized study was conducted.Methods: Infected dyspeptic patients received pantoprazole 40 mg, amoxicillin 1000 mg, and clarithromycin 500 mg, all twice daily, for 7 days (PAC7); or pantoprazole 40 mg twice daily, bismuth subcitrate 108 mg, and tetracycline 500 mg, both 4 times daily, and metronidazole 200 mg 3 times daily and 400 mg at night for 7 days (PBTM7); bismuth subcitrate 108 mg and tetracycline 500 mg, both 4 times daily, and metronidazole 200 mg 3 times daily and 400 mg at night for 14 days (BTM14). Outcome was assessed with ¹³C-urea breath test.Results: Eradication rates (intention to treat [n = 405]/per protocol [n = 320]) were similar for PAC7 (78%/82%) and PBTM7 (82%/88%); the latter significantly superior to BTM14 (69%/74%; P < 0.01). Pretreatment metronidazole resistance (MR) was 53% and clarithromycin resistance was 8%. Eradication rates for primary metronidazole sensitive/resistant isolates were 74%/87% with PAC7 and 80%/81% for PBTM7, compared with 76%/55% (P < 0.02) for BTM14. Noncompliance was greater with BTM14 (15%; P < 0.001) than PAC7 (3%) or PBTM7 (6%). Moderate-severe adverse events were more common with BTM14 (45%; P < 0.001), than PAC7 (23%) or PBTM7 (25%) with more discontinuations (9%, 2%, 3%, respectively).Conclusions: One-week PPI triple therapy is well tolerated and effective. The addition of PPI to bismuth triple therapy allows reduction of treatment duration with improved efficacy and tolerability, despite a high rate of MR. Quadruple therapy appears to overcome pretreatment MR in most cases. Two-week bismuth triple therapy is significantly inferior to quadruple therapy and less well tolerated than both 1-week therapies.

High performance BaBiScCo hollow fibre membranes for oxygen transport

Here we report the production of novel high performance BaBi_0.05Sc_0.1Co_0.85O_3-3 (BaBiScCo) hollow fibres delivering oxygen fluxes of 11.4 ml cm^-2 min^-1 at 950 °C. The doping of bismuth, a highly ionic conductor, at the B-site of a barium based perovskite overcame oxygen ionic transport limitations even at temperatures as low as 600 °C.

Facile preparation and thermoelectric properties of Bi₂Te₃ based alloy nanosheet/PEDOT:PSS composite films

Bi2Te3 based alloy nanosheet (NS)/poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) composite films were prepared separately by spin coating and drop casting techniques. The drop cast composite film containing 4.10 wt % Bi2Te3 based alloy NSs showed electrical conductivity as high as 1295.21 S/cm, which is higher than that (753.8 S/cm) of a dimethyl sulfoxide doped PEDOT:PSS film prepared under the same condition and that (850-1250 S/cm) of the Bi2Te3 based alloy bulk material. The composite film also showed a very high power factor value, ∼32.26 μWm(-1) K(-2). With the content of Bi2Te3 based alloy NSs increasing from 0 to 4.10 wt %, the electrical conductivity and Seebeck coefficient of the composite films increase simultaneously.