The Influence of Adding a Functionalized Fluoroalkyl Silanes (PFDTES) into a Novel Silica-Based Hybrid Coating on Corrosion Protection Performance on an Aluminium 2024-t3 Alloy

Silica-based coatings prepared using sol-gel polymerizing technology have been shown to exhibit excellent chemical stability combined with reducing the corrosion of metal substrates, showing promising use in aerospace and marine applications to protect light alloys. Moreover, this technology is an eco-friendly technique route for producing surface coatings, showing high potential for replacing toxic pre-treatment coatings of traditional conversation chromate coatings. This study aims to investigate the enhancement in corrosion protection of a hybrid-organic-inorganic silica-based coating cured at 80 °C by increasing the hydrophobicity to work on the aluminium 2024-T3 alloy. This approach involving a novel silica-based hybrid coating was prepared by introducing 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES) into the base hybrid formula created from tetraethylorthosilicatesilane (TEOS) and triethoxymethylsilane (MTMS) precursors; this formula was enhanced by introducing a Polydimethylsiloxane polymer (PDMS). The corrosion protection properties of these coatings were examined by being immersed in 3.5% NaCl with electrochemical impedance testing (EIS) and Potentiodynamic polarization scanning (PDPS). The chemical elements confirmation was performed using infrared spectroscopy (ATR-FTIR); all this was supported by analysing the surface morphology before and after the immersion by using scanning electron microscopy (SEM). The results of the electrochemical impedance testing analyses reveal the new open finite-length diffusion circuit element due to electrolyte media diffusion prevented by fluorinated groups. Additionally, it shows increases in corrosion protection arising from the increasing hydrophobicity of the fluorinated coating compared to other formulas cured under similar conditions and bare substrate. Additionally, the modified sol-gel exhibited improved resistance to cracking, while the increased hydrophobicity may also promote self-cleaning.

Phenotyping patients with borderline elevated esophageal acid exposure

Summary Acid exposure time (AET) <4% on ambulatory reflux monitoring definitively rules out pathologic gastroesophageal acid reflux, while AET >6% indicates pathologic reflux per the Lyon Consensus, leaving AET of 4–6% as borderline. We aimed to elucidate the borderline AET population and identify metrics that could help differentiate this group. A total of 50 subjects in each group, AET <4, 4–6, and >6% on pH-impedance monitoring between 2015 and 2019, were retrospectively reviewed. In addition to demographic and clinical information, the extracted data included mean nocturnal baseline impedance (MNBI) on reflux study and high-resolution manometry (HRM) parameters and diagnosis. After excluding patients with prior foregut surgery, major esophageal motility disorder, or unreliable impedance testing, a total of 89 subjects were included in the analysis (25 with normal AET < 4%, 38 with borderline 4–6%, 26 with abnormal >6%). MNBI in borderline AET patients was significantly lower compared to normal AET (1607.7 vs. 2524.0 ohms, P < 0.01), and higher than abnormal AET (951.5 ohms, P < 0.01). Borderline subjects had a greater frequency of ineffective esophageal motility (IEM) diagnosis per Chicago classification v3.0 (42.1 vs. 8.0%, P = 0.01), but did not demonstrate any differences compared to abnormal subjects (34.6%, P = 0.56). Patients with borderline AET had an average MNBI that was in between normal AET and abnormal AET. Borderline AET patients also commonly demonstrate IEM on HRM, similar to those with abnormal AET. Our findings can be potentially useful in assigning higher clinical significance for patients found to have borderline AET with concomitant low MNBI and IEM on manometry.

Impedance testing of porous Si3N4 scaffolds for skeletal implant applications

Si3N4 ceramics show excellent characteristics of mechanical and chemical resistance in combination with good biocompatibility, antibacterial property and radiolucency. Therefore, they are intensively studied as structural materials in skeletal implant applications. Despite their attractive properties, there are limited data in the field about in vitro studies of cellular growth on ceramic implant materials. In this study, the growth of bone cells was investigated on porous silicon nitride (Si3N4) ceramic implant by using electrochemical impedance spectroscopy (EIS). Partial sintering was performed at 1700 °C with limited amount of sintering additive for the production of porous Si3N4 scaffolds. All samples were then sterilized by using ethylene oxide followed by culturing MG-63 osteosarcoma cells on the substrates for in vitro assays. At 20 and 36 h, EIS was performed and results demonstrated that magnitude of the impedance as a result of the changes in the culture medium increased after incubation with osteosarcoma cells. The changes are attributed to the cellular uptake of charged molecules from the medium. Si3N4 samples appear to show large impedance magnitude changes, especially between 100 and 1 Hz. Impedance changes were also correlated with WST-1 measurements (36 h) and DAPI results.

Validation of Peptest™ in Patients with Gastro-Esophageal Reflux Disease and Laryngopharyngeal Reflux Undergoing Impedance Testing

Background and Aims: Pepsin in the gastric refluxate is a marker for a prior reflux event and rapid detection might be achieved using the Peptest™, an in vitro diagnostic medical device. The aim of this study was to validate the use of Peptest™ to reliably diagnose reflux in patients with gastro-esophageal reflux disease (GERD) and laryngopharyngeal reflux (LPR) disease diagnosed with multichannel intraluminal impedance/ pHmetry (MII-pH). Methods: 20 reflux patients were recruited of whom 10 had classical GERD and 10 had LPR. All patients underwent MII-pH and provided expectorated saliva samples when a MII-pH reflux event was observed, or reflux symptoms were experienced, and all were tested for the presence of pepsin using the Peptest™. Results: Pepsin was detected in 31 out of 45 samples (68.9%). At least 1 positive pepsin result was seen in 16 patients (80%) and this was the same, irrespective of the GERD or LPR diagnosis. Peptest™ had a positive predictive value of 69% to detect MII-pH reflux events. Conclusions: Peptest™ is a good first-line diagnostic procedure to use in reflux sufferers to confirm the presence of reflux.

Measurement Techniques for Electromagnetic Shielding Behavior of Braided-Shield Power Cables: An Overview and Comparative Study

More and more EMC tests have shown that the radiated emission problems of the equipment under test mainly concentrate on the intercon- nected power cables and cable connectors. Measurement of shielding performance is a prerequisite for quantitative and qualitative evaluation of the frequency-dependent characteristic of braided-shield power cables and cable connectors. Due to the asymmetric geometric structures of these cable assemblies, compared with the coaxial and symmetrical communication cables, the commonly used transfer impedance testing methods may not be suitable. In view of this, several improved simple and effective measurement methods, including transfer impedance and shield reduction factor testing methods, were proposed in recent years. These methods, based on the equivalent circuit model of the characteristic parameters, provide good repeatability for the measurement of shielding performance. This paper presents an overview analysis of various measurement techniques for shielding performance of power cables and cable connectors, highlights some of its equivalence principle in measurement setups, and showcases a brief comparison between transfer impedance and shield reduction factor.