Corrosion and corrosion prevention in gas turbines

The conditions governing the corrosion behavior in gas turbines are surveyed. Factors such as temperature, relative humidity, the presence of sulfur and nitrogen dioxide, and fuel quality are discussed. Electromechanical corrosion at relatively low temperature in compressors; oxidation; and hot corrosion (sulfidation) at high temperature in turbines are considered. Corrosion prevention by washing and rinsing, fueld additives, and corrosion resistant materials and coatings are reviewed

Surface plasmon resonance immunosensors: sensitivity considerations

Some aspects of improving surface plasmon resonance response in immunosensing applications are considered. Both from calculations and experiments, it was found that maximum sensitivity is obtained for a silver layer about 55 nm thick in direct contact with the species to be quantified. Application of an intermediate layer with high permittivity can be useful in suppressing background responses. Experimentally, a protein surface-coverage fraction of ca. 0.1 could be measured, corresponding to ca. 10−10 mol1−1 antibody

Features of the Structure, Development, and Activity of the Zebrafish Noradrenergic System Explored in New CRISPR Transgenic Lines

The noradrenergic (NA) system of vertebrates is implicated in learning, memory, arousal, and neuroinflammatory responses, but is difficult to access experimentally. Small and optically transparent, larval zebrafish offer the prospect of exploration of NA structure and function in an intact animal. We made multiple transgenic zebrafish lines using the CRISPR/Cas9 system to insert fluorescent reporters upstream of slc6a2, the norepinephrine transporter gene. These lines faithfully express reporters in NA cell populations, including the locus coeruleus (LC), which contains only about 14 total neurons. We used the lines in combination with two‐photon microscopy to explore the structure and projections of the NA system in the context of the columnar organization of cell types in the zebrafish hindbrain. We found robust alignment of NA projections with glutamatergic neurotransmitter stripes in some hindbrain segments, suggesting orderly relations to neuronal cell types early in life. We also quantified neurite density in the rostral spinal cord in individual larvae with as much as 100% difference in the number of LC neurons, and found no correlation between neuronal number in the LC and projection density in the rostral spinal cord. Finally, using light sheet microscopy, we performed bilateral calcium imaging of the entire LC. We found that large‐amplitude calcium responses were evident in all LC neurons and showed bilateral synchrony, whereas small‐amplitude events were more likely to show interhemispheric asynchrony, supporting the potential for targeted LC neuromodulation. Our observations and new transgenic lines set the stage for a deeper understanding of the NA system

Pancreatic ductal adenocarcinoma and chronic pancreatitis may be diagnosed by exhaled-breath profiles:a multicenter pilot study

Background: The diagnosis of pancreatic adenocarcinoma and chronic pancreatitis often rely on expensive and invasive diagnostic approaches, which are not always discriminative since patients with chronic pancreatitis and pancreatic adenocarcinoma may present with similar symptoms. Volatile organic compounds (VOCs) in expired breath, could be used as a non-invasive diagnostic biological marker for detection of pancreatic pathology. Detection and discrimination of pancreatic pathology with an electronic nose has not yet been reported. Purpose: The objective of this pilot study was to determine the diagnostic potential of an electronic nose to identify pancreatic adenocarcinoma and chronic pancreatitis by analyzing volatile organic compoundg (VOC) profiles in exhaled air. Patients and methods: In a multicenter study, the exhaled air of 56 chronic pancreatitis patients, 29 pancreatic adenocarcinoma patients, and 74 disease controls were analyzed using an electronic nose based on 3 metal oxide sensors (MOS). The measurements were evaluated utilizing an artificial neural network. Results: VOC profiles of chronic pancreatitis patients could be discriminated from disease controls with an accuracy of 0.87 (AUC 0.95, sensitivity 80%, specificity 92%). Also, VOC profiles of patients with pancreatic adenocarcinoma differed from disease controls with an accuracy of 0.83 (AUC 0.87, sensitivity 83%, specificity 82%). Discrimination between chronic pancreatitis and pancreatic adenocarcinoma showed an accuracy of 0.75 (AUC 0.83, sensitivity 83%, specificity 71%). Conclusion: An electronic nose may be a valuable diagnostic tool in diagnosis of pancreatic adenocarcinoma and chronic pancreatitis. The current study shows the potential of an electronic nose for discriminating between chronic pancreatitis, pancreatic adenocarcinoma and healthy controls. The results from this proof-of-concept study warrant external validation in larger cohorts

Twenty-Four Hour Tonometry in Patients Suspected of Chronic Gastrointestinal Ischemia

Background and aims: Gastrointestinal tonometry is currently the only clinical diagnostic test that enables identification of symptomatic chronic gastrointestinal ischemia. Gastric exercise tonometry has proven its value for detection of ischemia in this patients group, but has its disadvantages. Earlier studies with postprandial tonometry gave unreliable results. In this study we challenged (again) the use of postprandial tonometry in patients suspected of gastrointestinal ischemia. Methods: Patients suspected for chronic gastrointestinal ischemia had standard diagnostic work up, including gastric exercise tonometry and 24-h tonometry using standard meals. Results: Thirty-three patients were enrolled in the study. Chronic gastrointestinal ischemia was diagnosed in 17 (52%) patients. The 24-h tonometry correctly predicted the presence of ischemia in 13/17 patients, and absence of ischemia in 15/16 patients. Conclusions: The use of 24-h tonometry after meals in patients suspected of gastrointestinal ischemia seems feasible, with promising accuracy for the detection of ischemia

Quality of life temporarily improved in patients in whom the diagnosis chronic mesenteric ischemia wasn’t confirmed after multidisciplinary evaluation in a tertiary referral centre

Objectives: Chronic Mesenteric Ischemia (CMI) is a disease in which abdominal symptoms are caused by insufficient mesenteric blood supply. Treatment results in improved quality of life (QoL). To put these results into perspective, the QoL of patients with symptoms potentially complying with CMI but without confirmation of the diagnosis was studied from six months up to four years.Methods: Between May and July 2020 follow-up questionnaires were sent to 144 patients that were suspected of CMI but in whom the diagnosis was not confirmed after a thorough multidisciplinary evaluation in a CMI expert centre. The baseline QoL was measured at first presentation. Three cohorts were included: 50 patients with a follow-up of six months, 45 patients with a follow-up of two years, and 49 patients with a follow-up of four years were invited to participate. The QoL was measured on a 100 points Visual Analogue Scale (VAS). A minimal clinically important difference of 7.5 was used as non-inferiority threshold.Results: The response rates were 34/50 (68%), 33/45 (73%), and 34/49 (69%). QoL improved in the six months group, with a mean change of 19 in VAS score (95% CI 11-27), in which baseline QoL was inferior to the QoL at follow-up (lower bound 95% CI above >7.5 threshold). The change in QoL was inconclusive in the other two groups, respectively 15 (95% CI 6-24) and 3 (95% CI -6-13). Furthermore, there was no significant change in QoL between patients without mesenteric stenosis and with one or two vessel stenosis (P=0.36) and between patients with occlusive stenosis and anatomic Median Arcuate Ligament Syndrome (MALS) (P=0.53).Conclusion: The QoL of patients suspected for CMI was clinically significantly improved after six months without additional treatment. However, this improvement faded completely after four years

Non-classical clinical presentation at diagnosis by male celiac disease patients of older age

BACKGROUND: . In a biopsy-proven adult celiac disease (CeD) cohort from the Netherlands, male patients were diagnosed with CeD at significantly older ages than female patients. OBJECTIVES: To identify which factors contribute to diagnosis later in life and whether diagnostic delay influences improvement of symptoms after starting a gluten-free diet (GFD). METHODS: . We performed a questionnaire study in 211 CeD patients (67:144, male:female) with median age at diagnosis of 41.8 years (interquartile range: 25-58) and at least Marsh 2 histology. RESULTS: . Classical symptoms (diarrhea, fatigue, abdominal pain and/or weight loss) were more frequent in women than men, but sex was not significantly associated with age at diagnosis. In a multivariate analysis, a non-classical presentation (without any classical symptoms) and a negative family history of CeD were significant predictors of older age at diagnosis (coefficients of 8 and 12 years, respectively). A delay of >3 years between first symptom and diagnosis was associated with slower improvement of symptoms after start of GFD, but not with sex, presentation of classical symptoms or age at diagnosis. CONCLUSION: . Non-classical CeD presentation is more prevalent in men and is associated with a diagnosis of CeD later in life. Recognizing CeD sooner after onset of symptoms is important because a long diagnostic delay is associated with a slower improvement of symptoms after starting a GFD

Retention of basic laparoscopic skills after a structured training program

The purpose of this study was to test the retention of basic laparoscopic skills on a box trainer 1 year after a short training program. For a prior study, eight medical students without prior experience (novices) underwent baseline testing, followed by five weekly training sessions and a final test. During each of seven sessions, they performed five tasks on an inanimate box trainer. Scores were calculated by adding up the time to completion of the task with penalty points, consequently rewarding speed and precision. The sum score was the sum of the five scores. One year later, seven of them underwent retention testing for the current study. The final test results were compared with retention test results as a measure of durability of acquired skills. Novices’ scores did not worsen significantly for four out of five tasks (i.e., placing a pipe cleaner p = 0.46, placing beads p = 0.24, cutting a circle p = 0.31, and knot tying p = 0.13). However, deterioration was observed in the performance on stretching a rubber band (p < 0.05), as well as in the sum score (p < 0.05). Nevertheless, all retention scores remained better than the baseline results. In conclusion, basic laparoscopic skills acquired during a short training program merely sustain over time. However, ongoing practice is advisable, especially to preserve tissue-handling skills, since these may be the first to deteriorate