Theoretical and Numerical Investigation of Liquid-Gas Interface Location of Capillary Driven Flow During the Time Throughout Circular Microchannels

The main aim of this study is to find the best, most rapid, and the most accurate numerical method to find the liquid-gas interface of capillary driven flow during the time in circular Microchannels by using COMSOL Multiphysics software. Capillary driven flow by eliminating micropumps or any physical pressure gradient generators can make the microfluidic devices cheaper and more usable. Hence, by using this two-phase flow, the final costs of lots of microfluidic devices and lab-on-a-chip can significantly be decreased and help them to be commercialized. The first step to employing the capillary flow in these devices is the simulation of this flow inside the microchannels. One of the most common and valid software for this work is COMSOL Multiphysics; this fact reveals the importance of this study. In this research study, simulation results obtained by using two possible numerical methods in this software, for capillary flows of water and ethanol in two different circular microchannels, verified and compared with four other methods, which verified experimentally before. Finally, the most accurate and time-saving numerical method of this software will be specified. This appropriate technique can contribute to simulate microfluidic and lab-on-a-chip devices, which are made of different mechanical and electrical parts, in COMSOL Multiphysics software by choosing the best method.Comment: 7 pages, 13 figures, 7 tables, 2017 5th International Conference on Robotics and Mechatronics (ICROM

Correlation of dysoxia metabolism markers with trauma scoring systems in multiple trauma patients admitted to the emergency department: A cross-sectional observational study

Background: All the trauma scoring systems (TSSs) have some limitations, and none is useful for patient monitoring. Recently, investigators have tried to modify the TSSs to improve their use. Aims: This study was conducted to determine whether any correlation exists between dysoxia metabolism markers (DMMs), including venous base deficit (BD) and HCO3level with different TSSs. Materials and Methods: In this cross-sectional study, all multiple trauma patients admitted to the emergency department were eligible. Blood samples for venous blood gas analysis were taken at the onset of resuscitation process. TSSs, including trauma index (TI), abbreviated injury score (AIS), Injury Severity Score (ISS), Revised Trauma Score (RTS), and Trauma Score-ISS (TRISS), were calculated for the patients. Spearman's rank correlation coefficient test was applied to find the association between the independent variables. Results: A total of 285 patients with a mean age of 33.37 ± 15.29 fulfilled the inclusion criteria, of which, 211 cases (74.0) were male. Statistical analysis revealed that there was a correlation between TI and HCO3level (P = 0.0001, r = 0.37) and also TI and BD (P = 0.0001, r = 0.47). Furthermore, there was an indirect correlation between AIS and ISS with HCO3and BD levels and the direct correlation between RTS and TRISS with HCO3and BD levels. Conclusion: It is likely that there is a statistical correlation, although weak, between TSSs with DMMs, including HCO3and BD level

Fabrication and verification of a single aligned nanofibre gas sensor based on non‐contact direct writing method

Abstract In this letter, the non‐contact direct writing method for producing single aligned fibre utilizing polyvinylpyrrolidone (PVP) polymer has been explored. It has been shown that with the help of this method, nanofibres can be created in a controlled manner with designed structures. This form of nanofibres is being studied with the goal of using it in carbon monoxide (CO) gas sensors. The temperature required for the annealing operation was 500°C, and finally the authors obtained nanofibres with diameter of 200 nm. In addition, a simulation technique built on the Monte Carlo method has also been introduced. It is shown that this simulation method is compatible with the experimental results with reasonable accuracy. The results showed that the authors have a correlation of about 0.934 between experimental results obtained in 30 ppb of CO gas and its simulation data

Fabrication of Pd Doped WO3 Nanofiber as Hydrogen Sensor

Pd doped WO3 fibers were synthesized by electro-spinning. The sol gel method was employed to prepare peroxopolytungstic acid (P-PTA). Palladium chloride and Polyvinyl pyrrolidone (PVP) was dissolved in the sol Pd:WO3 = 10% molar ratio. The prepared sol was loaded into a syringe connected to a high voltage of 18.3 kV and electrospun fibers were collected on the alumina substrates. Scanning electron microscope (SEM), X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques were used to analyze the crystal structure and chemical composition of the fibers after heat treatment at 500 °C. Resistance-sensing measurements exhibited a sensitivity of about 30 at 500 ppm hydrogen in air, and the response and recovery times were about 20 and 30 s, respectively, at 300 °C. Hydrogen gas sensing mechanism of the sensor was also studied

Detection of retinal capillary nonperfusion in fundus fluorescein angiogram of diabetic retinopathy

Introduction: Retinal capillary nonperfusion (CNP) is one of the retinal vascular diseases in diabetic retinopathy (DR) patients. As there is no comprehensive detection technique to recognize CNP areas, we proposed a different method for computing detection of ischemic retina, non-perfused (NP) regions, in fundus fluorescein angiogram (FFA) images. Methods: Whilst major vessels appear as ridges, non-perfused areas are usually observed as ponds that are surrounded by healthy capillaries in FFA images. A new technique using homomorphic filtering to correct light illumination and detect the ponds surrounded in healthy capillaries on FFA images was designed and applied on DR fundus images. These images were acquired from the diabetic patients who had referred to the Nikookari hospital and were diagnosed for diabetic retinopathy during one year. Our strategy was screening the whole image with a fixed window size, which is small enough to enclose areas with identified topographic characteristics. To discard false nominees, we also performed a thresholding operation on the screen and marked images. To validate its performance we applied our detection algorithm on 41 FFA diabetic retinopathy fundus images in which the CNP areas were manually delineated by three clinical experts. Results: Lesions were found as smooth regions with very high uniformity, low entropy, and small intensity variations in FFA images. The results of automated detection method were compared with manually marked CNP areas so achieved sensitivity of 81%, specificity of 78%, and accuracy of 91%.The result was present as a Receiver operating character (ROC) curve, which has an area under the curve (AUC) of 0.796 with 95% confidence intervals. Conclusion: This technique introduced a new automated detection algorithm to recognize non-perfusion lesions on FFA. This has potential to assist detecting and managing of ischemic retina and may be incorporated into automated grading diabetic retinopathy structures

Developed wearable miniature sensor to diagnose initial perturbations of cardiorespiratory system

The progress of microelectromechanical systems tends to fabricate miniature motion sensors that can be used for various purposes of biomedical systems, particularly on-body applications. A miniature wireless sensor is developed that not only monitors heartbeat and respiration rate based on chest movements but also identifies initial problems in the cardiorespiratory system, presenting a healthy measure defined based on height and length of the normal distribution of respiration rate and heartbeat. The obtained results of various tests are compared with two commercial sensors consisting of electrocardiogram sensor as well as belt sensor of respiration rate as a reference (gold standard), showing that the root-mean-square errors obtain <2.27 beats/min for a heartbeat and 0.93 breaths/min for respiration rate. In addition, the standard deviation of the errors reaches <1.26 and 0.63 for heartbeat and respiration rates, separately. According to the outcome results, the sensor can be considered an appropriate candidate for in-home health monitoring, particularly early detection of cardiovascular system problems

Assessment of human gait after total knee arthroplasty by dynamic time warping algorithm

Abstract Today, the elderly population is increasing, and there are many drawbacks for them, especially defects in their knee joints which lead to improper gait. To solve this problem, their knee joint can be replaced with knee arthroplasty. In this letter, level of improvement in the human gait before and after total knee arthroplasty (TKA) surgery is investigated using the dynamic time warping (DTW) algorithm. For this purpose, several volunteers who have problems with their knees are incorporated in a test before and after TKA surgery. Then, the data of gait analysis is collected and the data is compared with a reference using the DTW algorithm. The outcome results illustrate an improvement of 89%–97% by the proposed algorithm after TKA surgery. Therefore, patients can see improvement with high accuracy and very fast that result in more use this technique in TKR surgery

Very late effects of postoperative atrial fibrillation on outcome of coronary artery bypass graft surgery

Background: Atrial fibrillation (AF) after coronary artery bypass graft (CABG) is a common complication with potentially higher risk of adverse outcome and prolonged hospital stay. Objective: To determine the impact of postoperative AF (POAF) on long-term outcome in a large cohort of patients who underwent CABG. Patients and Methods: We conducted an observational cohort study of 989 patients who underwent isolated CABG with more than 5-year follow-up. Patient divided in two groups: patients with and without POAF. Results: In this study, atrial fibrillation developed after CABG in 156 patients (15.8%). Patients with POAF were generally older (P = 0.001) and presented more often with comorbidities including congestive heart failure (P = 0.001), hypertension (P = 0.001), peripheral vascular disease (P = 0.001), hyperlipidemia (P = 0.009), and renal failure (P = 0.001). Five-year mortality was observed in 23 (2.3%) patients. Patients with POAF had higher five-year mortality rate than those without POAF. Multivariate logistic analysis showed that AF after surgery has a strong effect on mortality (HR, 3.3; 95% CI, 0.04-10.8, P = 0.04) and morbidity rates (HR, 4.0; 95% CI, 2.35-6.96, P = 0.001). Conclusions: Postoperative atrial fibrillation strongly predicts higher long-term mortality and morbidity following coronary artery bypass graft