Redox Cycling for SOFC Accelerated Degradation

This work aims at development of Accelerated Stress Tests for SOFC via artificial aging of the fuel electrode applying chemical and electrochemical (hydrogen starvation) redox cycling. In principle the degradation processes follows that of calendar aging (Ni coarsening and migration), but in addition it can bring to irreversible damages caused by the development of cracks at the interface anode/electrolyte due to the expansion/shrinkage of the Ni network. The challenge is to introduce conditions which will prevent the formation of cracks which can be done by partial oxidation. The advantage of the proposed methodology is that a mild level of oxidation can be regulated by direct impedance monitoring of the Ni network resistance changes during oxidation/reduction. Once the redox cycling conditions are fixed on bare anode and checked on anode/electrolyte sample for eventual cracks, the procedure can be introduced for AST in full cell configuration. The developed methodology is evaluated by comparative impedance analysis of artificially aged and calendar aged button cells. The results for 20 redox cycles which can be performed for 24 hours are comparable with those obtained for about 1600 hours operation in standard conditions which ensures more than 50 times acceleration.

How effective is laparoscopic redo-antireflux surgery?

Summary Background: The failure-rate after primary antireflux surgery ranges from 3 to 30%. Reasons for failures are multifactorial. The aim of this study is to gain insight into the complex reasons for, and management of, failure after antireflux surgery. Methods: Patients were selected for redo-surgery after a diagnostic workup consisting of history and physical examination, upper gastrointestinal endoscopy, quality-of-life assessment, screening for somatoform disorders, esophageal manometry, 24-hour-pH-impedance monitoring, and selective radiographic studies such as Barium-sandwich for esophageal passage and delayed gastric emptying. Perioperative and follow-up data were compiled between 2004 and 2017. Results: In total, 578 datasets were analyzed. The patient cohort undergoing a first redo-procedure (n = 401) consisted of 36 patients after in-house primary LF and 365 external referrals (mean age: 62.1 years [25–87]; mean BMI 26 [20–34]). The majority of patients underwent a repeated total or partial laparoscopic fundoplication. Major reasons for failure were migration and insufficient mobilization during the primary operation. With each increasing number of required redo-operations, the complexity of the redo-procedure itself increased, follow-up quality-of-life decreased (GIQLI: 106; 101; and 100), and complication rate increased (intraoperative: 6,4–10%; postoperative: 4,5–19%/first to third redo). After three redo-operations, resections were frequently necessary (morbidity: 42%). Conclusions: Providing a careful patient selection, primary redo-antireflux procedures have proven to be highly successful. It is often the final chance for a satisfying result may be achieved upon performing a second redo-procedure. A third revision may solve critical problems, such as severe pain and/or inadequate nutritional intake. When resection is required, quality of life cannot be entirely normalized.

СУТОЧНАЯ МНОГОКАНАЛЬНАЯ РН-ИМПЕДАНСОМЕТРИЯ ПИЩЕВОДА В ДИАГНОСТИКЕ ГАСТРОЭЗОФАГЕАЛЬНОЙ РЕФЛЮКСНОЙ БОЛЕЗНИ (КЛИНИЧЕСКИЕ СЛУЧАИ)

Background. Gastroesophageal reflux disease (GERD) is an urgent problem of modern gastroenterology as well as the most common pathology of the upper gastrointestinal tract; it is a chronic disease that significantly reduces the patient's quality of life, increases the risk of developing Barrett's esophagus and esophageal adenocarcinoma. Objective. To assess the potentials of multichannel intraluminal pH impedance monitoring in the diagnosis of esophageal diseases. Material and methods. In 3 patients with clinical and endoscopic signs of GERD esophageal multichannel intraluminal pH-impedance monitoring was performed using the diagnostic equipment Digitrapper pH-Z from Given Imaging (USA). Results. 24-hour esophageal pH monitoring enabled to verify the diagnosis of GERD, to reveal a hypersensitive esophagus and manifestations of nocturnal acid breakthrough. Conclusions. Multichannel intraluminal pH-impedance monitoring is the "gold standard" for the diagnosis of esophageal diseases; it significantly expands opportunities of gastroenterologists in the treatment of GERD.

Smart PZT-Embedded Sensors for Impedance Monitoring in Prestressed Concrete Anchorage

This study investigates the feasibility evaluation of smart PZT-embedded sensors for impedance-based damage monitoring in prestressed concrete (PSC) anchorages. Firstly, the concept of impedance-based damage monitoring for the concrete anchorage is concisely introduced. Secondly, a prototype design of PZT-embedded rebar and aggregate (so-called smart rebar–aggregate) is chosen to sensitively acquire impedance responses-induced local structural damage in anchorage members. Thirdly, an axially loaded concrete cylinder embedded with the smart rebar–aggregate is numerically and experimentally analyzed to investigate their performances of impedance monitoring. Additionally, empirical equations are formulated to represent the relationships between measured impedance signatures and applied compressive stresses. Lastly, an experimental test on a full-scale concrete anchorage embedded with smart rebar–aggregates at various locations is performed to evaluate the feasibility of the proposed method. For a sequence of loading cases, the variation in impedance responses is quantified to evaluate the accuracy of smart rebar–aggregate sensors. The empirical equations formulated based on the axially loaded concrete cylinder are implemented to predict compressive stresses at sensor locations in the PSC anchorage.

Fabrication of Planar Microelectrode Array Using Laser-Patterned ITO and SU-8

For several decades, microelectrode array (MEA) has been a powerful tool for in vitro neural electrophysiology because it provides a unique approach for monitoring the activity of a number of neurons over time. Due to the various applications of MEAs with different types of cells and tissues, there is an increasing need to customize the electrode designs. However, the fabrication of conventional MEAs requires several microfabrication procedures of deposition, etching, and photolithography. In this study, we proposed a simple fabrication method with a laser-patterned indium tin oxide (ITO) conductor and SU-8 photoresist insulation. Unlike in a conventional metal patterning process, only the outlines of ITO conductors are ablated by laser without removing background ITO. Insulation is achieved simply via SU-8 photolithography. The electrode sites are electroplated with iridium oxide (IrOX) to improve the electrochemical properties. The fabricated MEAs are electrochemically characterized and the stability of insulation is also confirmed by impedance monitoring for three weeks. Dissociated neurons of rat hippocampi are cultured on MEAs to verify the biocompatibility and the capacity for extracellular neural recording. The electrochemical and electrophysiological results with the fabricated MEAs are similar to those from conventional SiNX-insulated MEAs. Therefore, the proposed MEA with laser-patterned ITO and SU-8 is cost-effective and equivalently feasible compared with the conventional MEAs fabricated using thin-film microfabrication techniques.

500 THE PATHOLOGICAL GASTROESOPHAGEAL REFLUX IN PATIENTS WITH CYSTIC FIBROSIS

The presence of gastroesophageal reflux in patients after lung transplantation rises the risk of posttransplantant complications. The aim of our study was to evaluate the severity of gastroesophageal reflux (GER) in patients with cystic fibrosis before lung transplantation. Methods 14 patients with cystic fibrosis, who refferred to our Centre, were included in this study, mean age 28,86 ± 2,5 (6 males and 8 females). The diagnosis of cystic fibrosis was established at the age of 1–5 y.o. according to clinic, sweet test and genetic tests. All patients were performed upper endoscopy, X-ray, esophageal manometry and 24 h impedance monitoring. PPI treatment was excluded for 7 days before monitoring. Pathologic GER was established when total number of refluxes in distal esophagus was more than 75, the total number of refluxes in proximal esophagus was more than 20% of those in the distal part. Results According to endoscopy, none of patients had erosions of the esophagus. Five patients had ineffective motility and one—diffuse esophageal spazm. 56% of patients had pathologic number of refluxes in distal esophagus. 80% subjects had pathologic refluxes in proximal esophagus. The mean number of total refluxes in distal part was 54,93 ± 5,7, in proximal part—27,64 ± 2,6 (it is 40% of those in distal part). The distribution of acid and non-acid refluxes in patients with pathologic refluxes was 2:1. We didn’t reveal any correlation between number of refluxes, ineffective motility and gastric emptying. Conclusion despite normal upper endoscopy, 56% of patients with cystic fibrosis have pathologic gastroesophageal reflux. Besides, the study showed high propagation of GER to proximal esophagus in 80% of subjects, which may play role in posttransplantation period.