A Comparative Study of CCM and CCS Membrane Electrode Assemblies for High-Temperature Proton Exchange Membrane Fuel Cells with a CsH5(PO4)2-Doped Polybenzimidazole Membrane.

Membrane electrode assemblies (MEAs) are critical components in influencing the electrochemical performance of high-temperature proton exchange membrane fuel cells (HT-PEMFCs). MEA manufacturing processes are mainly divided into the catalyst-coated membrane (CCM) and the catalyst-coated substrate (CCS) methods. For conventional HT-PEMFCs based on phosphoric acid-doped polybenzimidazole (PBI) membranes, the wetting surface and extreme swelling of the PA-doped PBI membranes make the CCM method difficult to apply to the fabrication of MEAs. In this study, by taking advantage of the dry surface and low swelling of a CsH5(PO4)2-doped PBI membrane, an MEA fabricated by the CCM method was compared with an MEA made by the CCS method. Under each temperature condition, the peak power density of the CCM-MEA was higher than that of the CCS-MEA. Furthermore, under humidified gas conditions, an enhancement in the peak power densities was observed for both MEAs, which was attributed to the increase in the conductivity of the electrolyte membrane. The CCM-MEA exhibited a peak power density of 647 mW cm-2 at 200 °C, which was ~16% higher than that of the CCS-MEA. Electrochemical impedance spectroscopy results showed that the CCM-MEA had lower ohmic resistance, which implied that it had better contact between the membrane and catalyst layer.

Robust adaptive neural network integrated fault-tolerant control for underactuated surface vessels with finite-time convergence and event-triggered inputs.

In this paper, we study the trajectory tracking control of underactuated surface vessels(USVs) subject to actuator faults, uncertain dynamics, unknown environmental disturbances, and communication resource constraints. Considering that the actuator is prone to bad faults, the uncertainties formed by the combination of fault factors, dynamic uncertainties and external disturbances are compensated by a single online updated adaptive parameter. In the compensation process, we combine the robust neural-damping technology with the minimum learning parameters (MLPs), which improves the compensation accuracy and reduces the computational complexity of the system. To further improve the steady-state performance and transient response of the system, finite-time control (FTC) theory is introduced into the design of the control scheme. At the same time, we adopt the event-triggered control (ETC) technology, which reduces the action frequency of the controller and effectively saves the remote communication resources of the system. The effectiveness of the proposed control scheme is verified by simulation. Simulation results show that the control scheme has high tracking accuracy and strong anti-interference ability. In addition, it can effectively compensate for the adverse influence of fault factors on the actuator, and save the remote communication resources of the system.

A Review of Dry Deposition Schemes for Speciated Atmospheric Mercury.

This study reviewed the existing framework of dry deposition schemes for speciated atmospheric mercury. As the most commonly used methods for mercury dry deposition estimation, the big-leaf resistance scheme for gaseous oxidized mercury (GOM), the size distribution regarded resistance scheme for particulate bound mercury (PBM), and the bidirectional air-surface exchange scheme for gaseous elemental mercury (GEM) were introduced in detail. Sensitivity analysis were conducted to quantitatively identify the key parameters for the estimation of speciated mercury dry deposition velocities. The dry deposition velocity of GOM was found to be sensitive to the wind speed and some land use related parameters. The chemical forms of GOM could have a significant impact on the dry deposition velocity. The dry deposition velocity of PBM is sensitive to the mass fraction of PBM in coarse particles, while that of GEM is most sensitive to air temperature. Future research needs were proposed accordingly.

Biodegradation and optimization of bilge water in a sequencing batch reactor using response surface methodology.

Bilge water is a significant source of pollution in the marine environment and has captured widespread international attention. In this study, a sequencing batch reactor (SBR) combined with strain S2 identified as Bacillus licheniformis was employed to assess the biodegradation of Chemical Oxygen Demand (COD) from bilge water. The influencing variables such as temperature, pH level and inoculum concentration on the performance SBR system were optimized by utilizing response surface methodology (RSM). The experimental results showed that the maximum COD removal of 77.81% was reached at the optimal SBR operation conditions of temperature 35.44 °C pH 8.13, and inoculum concentration 31.47 mL. In the practical application of SBR, it was found that the decrease in hydraulic retention time (HRT) was accompanied by a decrease in COD degradation rate. The biodegradation kinetics of COD in bilge water were well fitted with the first-order equation with a higher R2 value of 0.98106. In conclusion, COD in bilge water can be efficiently biodegraded by SBR under the optimization of RSM.

One-stage CNN detector-based benthonic organisms detection with limited training dataset.

In this paper, focusing on the challenges in unique shape dimension and limited training dataset of benthonic organisms, an one-stage CNN detector-based benthonic organisms detection (OSCD-BOD) scheme is proposed. Main contributions are as follows: (1) The regression loss between the predicted bounding box and ground truth box is innovatively measured by the generalized intersection over union (GIoU), such that localization accuracy of benthonic organisms is dramatically enhanced. (2) By devising K-means-based dimension clustering, multiple benthonic organisms anchor boxes (BOAB) sufficiently exploring a priori dimension information can be finely derived from limited training dataset, and thereby significantly promoting the recall ability. (3) Geometric and color transformations (GCT)-based data augmentation technique is further resorted to not only efficiently prevent over-fitting training but also to significantly enhance detection generalization in complex and changeable underwater environments. (4) The OSCD-BOD scheme is eventually established in a modular manner by integrating GIoU, BOAB and GCT functionals. Comprehensive experiments and comparisons sufficiently demonstrate that the proposed OSCD-BOD scheme outperforms typical approaches including Faster R-CNN, SSD, YOLOv2, YOLOv3 and CenterNet in terms of mean average precision by 6.88%, 10.92%, 12.44%, 3.05% and 1.09%, respectively.

Activities of daily living associated with postoperative intensive care unit survival in elderly patients following elective major abdominal surgery: An observational cohort study.

ABSTRACT: Elderly patients who undergo major abdominal surgery are being in increasing numbers. Intensive care unit (ICU) survival is critical for surgical decision-making process. Activities of daily living (ADL) are associated with clinical outcomes in the elderly. We aimed to investigate the relationship between ADL and postoperative ICU survival in elderly patients following elective major abdominal surgery.We conducted a retrospective cohort study involving patients aged ≥65 years admitted to the surgical intensive care unit (SICU) following elective major abdominal surgery. Data from all patients were extracted from the electronic medical records. The Barthel Index (BI) was used to assess the level of dependency in ADL at the time of hospital admission.ICU survivors group had higher Barthel Index (BI) scores than non-survivors group (P < .001). With the increase of BI score, postoperative ICU survival rate gradually increased. The ICU survivals in patients with BI 0-20, BI 21-40, BI 41-60, BI 61-80 and BI 81-100 were 55.7%, 67.6%, 72.4%, 83.3% and 84.2%, respectively. In logistic regression, The Barthel Index (BI) was significantly correlated with the postoperative ICU survival in elderly patients following elective major abdominal surgery (OR = 1.33, 95% CI: 1.20-1.47, P = .02). The area under the receiver operating characteristic (ROC) curve of Barthel Index in predicting postoperative ICU survival was 0.704 (95% CI, 0.638-0.771). Kaplan-Meier survival curve in BI≥30 patients and BI < 30 patients showed significantly different.Activity of daily living upon admission was associated with postoperative intensive care unit survival in elderly patients following elective major abdominal surgery. The Barthel Index(BI) ≥30 was associated with increased postoperative ICU survival. For the elderly with better functional status, they could be given more surgery opportunities. For those elderly patients BI < 30, these results provide useful information for clinicians, patients and their families to make palliative care decisions.

Early versus late percutaneous dilational tracheostomy in critically ill patients anticipated requiring prolonged mechanical ventilation.

BACKGROUND: Tracheostomy should be considered to replace endotracheal intubation in patients requiring prolonged mechanical ventilation (MV). However, the optimal timing for tracheostomy is still a topic of debate. The present study aimed to investigate whether early percutaneous dilational tracheostomy (PDT) can reduce duration of MV, and to further verify whether early PDT can reduce sedative use, shorten intensive care unit (ICU) stay, decrease the incidence of ventilator associated pneumonia (VAP), and increase successful weaning and ICU discharge rate. METHODS: A prospective, randomized controlled trial was carried out in a surgical ICU from July 2008 to June 2011 in adult patients anticipated requiring prolonged MV via endotracheal intubation. Patients meeting the inclusion criteria were randomly assigned to the early PDT group or the late PDT group on day 3 of MV. The patients in the early PDT group were tracheostomized with PDT on day 3 of MV. The patients in the late PDT group were tracheostomized with PDT on day 15 of MV if they still needed MV. The primary endpoint was ventilator-free days at day 28 after randomization. The secondary endpoints were sedation-free days, ICU-free days, successful weaning and ICU discharge rate, and incidence of VAP at day 28 after randomization. The cumulative 60-day incidence of death after randomization was also analyzed. RESULTS: Total 119 patients were randomized to either the early PDT group (n = 58) or the late PDT group (n = 61). The ventilator-free days was significantly increased in the early PDT group than in the late PDT group ((9.57 ± 5.64) vs. (7.38 ± 6.17) days, P < 0.05). The sedation-free days and ICU-free days were also significantly increased in the early PDT group than in the late PDT group (20.84 ± 2.35 vs. 17.05 ± 2.30 days, P < 0.05; and 8.0 (interquartile range (IQR): 5.0 - 12.0) vs. 3.0 (IQR: 0 - 12.0) days, P < 0.001 respectively). The successful weaning and ICU discharge rate was significantly higher in early PDT group than in late PDT group (74.1% vs. 55.7%, P < 0.05; and 67.2% vs. 47.5%, P < 0.05 respectively). VAP was observed in 17 patients (29.3%) in early PDT group and in 30 patients (49.2%) in late PDT group (P < 0.05). There was no significant difference between the two groups in the cumulative 60-day incidence of death after randomization (P = 0.949). CONCLUSIONS: The early PDT resulted in more ventilator-free, sedation-free, and ICU-free days, higher successful weaning and ICU discharge rate, and lower incidence of VAP, but did not change the cumulative 60-day incidence of death in the patients' anticipated requiring prolonged mechanical ventilation.

The impact of dopamine on hemodynamics, oxygen metabolism, and cerebral resuscitation after restoration of spontaneous circulation in pigs.

BACKGROUND: Restoration of spontaneous circulation after cardiopulmonary resuscitation in cardiac arrest patients does not always signal a completely successful outcome. Functional deficiencies of the nervous system are found in many survivors of cardiac arrest. OBJECTIVES: To study the effects of dopamine-induced elevated blood pressure on the hemodynamics, oxygen metabolism, and cerebral resuscitation in different perfusion conditions in a resuscitated animal model. METHODS: There were 18 pigs included in the study. Ventricular fibrillation (VF) was induced with a programmed electrical stimulation device. After 4 min of untreated ventricular fibrillation followed by 9 min of CPR, 12 animals were resuscitated successfully, and were then randomly assigned to either the study group (dopamine group) or the control group (normal perfusion group). All animals in the two groups received normal saline through continuous intravenous guttae for 4 h at a rate of 15 mL/kg/h. In the study group, dopamine was added to raise the animals' blood pressure. Four hours of intensive monitoring was performed for all study animals. Finally, 24-h evaluation of neurological function was conducted in surviving animals in accordance with the standard of the Cerebral Performance Category Score. RESULTS: In animals in the dopamine group, the cardiac output, mean aortic pressure, coronary perfusion pressure, oxygen delivery, and oxygen consumption were higher than those found in the animals in the normal perfusion group (p < 0.05). Oxygen metabolism was remarkably improved in animals in the dopamine group. Furthermore, cerebral perfusion was better in the dopamine group than in the control group and thus, results of the evaluation of nervous system function were better in animals treated with dopamine (p < 0.05). CONCLUSIONS: Dopamine improved systemic perfusion, cerebral blood supply, and oxygen metabolism after successful resuscitation from VF in a porcine model. All of these factors have profound effects on the cerebral resuscitation.

A comparison of 2 types of chest compressions in a porcine model of cardiac arrest.

OBJECTIVE: Chest compressions performed by some medical workers are of poor quality, which are too few and shallow with incomplete release. This study was designed to compare the effects of these clinical quality chest compressions with standard manual chest compressions in a porcine model of cardiac arrest. METHODS: Ventricular fibrillation was induced in 18 pigs by programed electrical stimulation. Then, 40 mg methylene blue was injected into right atrium after 4 minutes of untreated ventricular fibrillation (VF), followed by cardiopulmonary resuscitation for 9 minutes. Defibrillation was attempted at 13 minutes of cardiac arrest. Animals of no restoration of spontaneous circulation after 4 times of defibrillations were announced dead and dissected immediately to observe the cerebral perfusion with methylene blue coloration. Resuscitated animals were executed to remove the tissues of pallium, cardiac muscle, kidney, and liver for histopathology after evaluating a porcine Cerebral Performance Category score at 24 hours after cardiac arrest. All animals were randomized to the following 2 groups: (1) standard manual chest compressions group (n = 9)-chest compression rates were kept at 100 +/- 5 cpm and compression depth at 50 +/- 1 mm with complete release by Heartstart MRx Monitor; (2) clinical quality chest compressions group (n = 9)-chest compression rates were kept at 80 +/- 5 cpm and compression depth at 37 +/- 1 mm with incomplete release. RESULTS: Compared with clinical quality chest compressions, standard manual chest compressions produced greater restoration of spontaneous circulation, neurologically normal 24-hour survival, and histopathologic findings. CONCLUSIONS: High-quality chest compressions improve outcomes of resuscitation, especially postresuscitation brain damage.