Weighted Rank Regression with Dummy Variables for Analyzing Accelerated Life Testing Data

In this article, we propose a new rank regression model to extrapolate the product lifetimes at normal operation environment from accelerated testing data. Weighted least squares method is used to compensate for nonconstant error variance in the regression model. A group of dummy variables is incorporated to check model adequacy. We also developed a customizing software for quick-and-easy implementation of the method so that reliability engineers can easily exploit it. Simulation studies show that, under light censoring, the proposed method performs comparatively well in predicting the lifetimes even with small sample sizes. With its computational ease and graphical presentation, the proposed method is expected to be more popular among reliability engineers

Thiol-linked peroxidase activity of human ceruloplasmin

AbstractHuman ceruloplasmin exhibited different antioxidant effects according to the electron donors in a metal-catalyzed oxidation system. Purified ceruloplasmin did not play a significant role in the protection of DNA strand breaks in the ascorbate/Fe3+/O2 system. However, when ascorbates were replaced with a thiol-reducing equivalent such as dithiothreitol, DNA strand breaks were significantly prevented by the same amount of ceruloplasmin. Ceruloplasmin did not catalyze the decomposition of H2O2 in the absence of reduced glutathione. On the contrary, ceruloplasmin showed a potent peroxidase ability to destroy H2O2 in the presence of reduced glutathione. In conclusion, the removal of H2O2 by human ceruloplasmin is not simply stoichiometric but thiol-dependent

Acetone Gas Sensing Properties of a Multiple-Networked Fe 2

Fe2O3-decorated CuO nanorods were prepared by Cu thermal oxidation followed by Fe2O3 decoration via a solvothermal route. The acetone gas sensing properties of multiple-networked pristine and Fe2O3-decorated CuO nanorod sensors were examined. The optimal operating temperature of the sensors was found to be 240°C. The pristine and Fe2O3-decorated CuO nanorod sensors showed responses of 586 and 1,090%, respectively, to 1,000 ppm of acetone at 240°C. The Fe2O3-decorated CuO nanorod sensor also showed faster response and recovery than the latter sensor. The acetone gas sensing mechanism of the Fe2O3-decorated CuO nanorod sensor is discussed in detail. The origin of the enhanced sensing performance of the multiple-networked Fe2O3-decorated CuO nanorod sensor to acetone gas was explained by modulation of the potential barrier at the Fe2O3-CuO interface, highly catalytic activity of Fe2O3 for acetone oxidation, and the creation of active adsorption sites by Fe2O3 nanoparticles

Pressure changes in the endotracheal tube cuff in otorhinolaryngologic surgery: a prospective observational study

ObjectiveInflation of the endotracheal tube cuff is needed for providing ventilation. Cuff pressure should be maintained inside the appropriate range to prevent critical airway complications. The purpose of this study is to evaluate the pressure changes in the endotracheal tube cuff during otorhinolaryngologic surgery.Design and methodThis single-center observational study was conducted at Severance Hospital in Korea between April 2020 and November 2020. Patients aged >20 years scheduled to undergo otorhinolaryngological surgical procedures were enrolled. Patients undergoing planned tracheostomy and those who were slated for uncuffed endotracheal tube use were excluded. Intubation was performed after the induction of general anesthesia. A pressure transducer was connected to the pilot balloon of the endotracheal tube, and cuff pressure was continuously monitored until extubation. If the cuff pressure was not appropriate for more than 5 min, it was adjusted to the appropriate range by injecting or removing air. The percentage of time for which the cuff pressure remained within the appropriate range was calculated and defined as the time in the therapeutic range (TTR). The presumed cause for the rise or fall in cuff pressure was identified.ResultsIn total 199 patients, alterations in cuff pressure outside the appropriate range occurred in 191 patients (96.0%). The mean TTR was 79.7% (SD 25.0%), and head and neck surgery had the lowest mean TTR of 69.0% compared to ear and nose surgeries (94.2 and 82.1%, respectively). Sixty-eight patients (34.2%) demonstrated inadequate endotracheal tube cuff pressure for more than 20% of the total anesthesia time. Twenty-six patients (13.1%) demonstrated optimal endotracheal tube cuff pressure for less than 50% of the total anesthesia time. The causative factors inducing inappropriate cuff pressure were found to vary, including positional changes, surgical procedure, anatomical manipulation, and anesthetic procedure.ConclusionIn otorhinolaryngologic surgery, cuff pressure increased or decreased outside the appropriate range due to various factors. Therefore, we suggest close continuous monitoring of cuff pressure during anesthesia for otorhinolaryngologic surgery.Clinical trial registrationclinicaltrials.gov, identifier NCT03938493

Total Gastrectomy in Gastric Conduit Cancer

We report a very rare case of surgery on gastric conduit cancer. A 67-year-old male patient underwent esophagectomy and intrathoracic esophagogastrostomy for squamous cell carcinoma of the lower thoracic esophagus 27 months ago. Upon follow-up, a gastric carcinoma at the intra-abdominal part of the gastric conduit was found on an esophagogastroduodenoscopy. We performed total gastrectomy and esophagocolonojejunostomy in the manner of Roux-en-Y anastomosis. The postoperative course was not eventful and an esophagogram on the 10th postoperative day showed no leakage or stenosis of the passage. The patient was discharged on the 17th day with no complications