In this paper, a novel 3-D microheater has been developed in order to improve the performance of catalytic gas sensors. The 3-D microheater consists of a platinum heater embedded in a concave-shaped membrane which was formed in twice wet-chemical anisotropic etching with photoresist-spray-coating-based liftoff process. Based on the 3-D microheater, a catalytic gas sensor with a paired detector and compensator was developed by sol-gel process, introducing γ-Al ₂ O ₃ -supported 15-wt % Pd as catalyst. Finite element method analysis results suggest that sensitivity of the catalytic gas sensor can be improved by loading more catalyst on the active area and concentrating more combustion heat inside the concave-shaped membrane. Test results indicate that a high heating efficiency has been achieved. Power per active area of the 3-D microheater is only half or less than that of current 2-D microheaters. Sensor response to methane shows that the sensitivity to 50% lower explosive limit CH ₄ was 12 mV/ % CH ₄ .

Background: Data on the clinical features and surgical outcomes of type A intramural hematoma (IMH) in Chinese patients are very limited. We aimed to present the surgical experiences on type A IMH in our center, and report early and late outcomes. Methods: From February 2012 to April 2018, 106 consecutive patients underwent open surgery for type A IMH at our hospital. We adopted emergent operation for patients with cardiac tamponade or other severe complications, and recommended initial medical treatment followed by elective surgery for stable patients. The composite endpoints included operative mortality, permanent nerve damage (stroke, paraplegia), and new-onset renal failure necessitating hemodialysis. Risk factors for operative mortality and the composite endpoints were identified using univariable and multivariable logistic regression model analysis. The survival and freedom from aortic events were analyzed using a Kaplan-Meier surviving curve and a log-rank test. Results: Except 1 patient receiving emergent surgery (within 24 hours from onset) because of cardiac tamponade and cerebral malperfusion, all patients received initial medical treatment and delayed surgery. Two patient developed pericardial tamponade while waiting for surgery, and then received emergent surgery. Preoperative conversion to aortic dissection (AD) was noted in no patient. The operative techniques included ascending aorta replacement in 9 patients, hemiarch replacement in 18 patients, total arch replacement (TAR) with frozen elephant trunk (FET) in 45 patient and hybrid aortic arch repair in 34 patients. The mean cardiopulmonary bypass (CPB) time and cross-clamp time were 138.7±41.6 and 79.3±27.8 min, respectively. The operative mortality was 1.9% (2/106). And the composite endpoints occurred in 7 patients. Multivariable logistic regression analysis showed CPB time ≥200 min and chronic kidney disease were risk factors for the composite endpoints. The follow-up data were available in 97 survivors, with the mean follow-up time of 30.8±16.2 months. Three patients died and 5 patients developed aortic events during the follow-up. The overall survival at 1-, 3- and 5-year were 97.0%, 95.3%, and 79.4%, respectively. And freedom from aortic events at 1-, 3- and 5-year were 97.7%, 95.3% and 89.4%, respectively. Conclusions: Our strategy had got low mortality and excellent mid-term survival in patients with type A IMH. Therefore, our strategy was suitable for the surgical repair of type A IMH in Chinese population.

A new tuyere small sleeve coating structure that balances the high thermal conductivity of the copper substrate with the high wear resistance of the protective layer was developed in this paper. This structure can achieve a low-carbon blast furnace by reducing the heat loss from the tuyere. The 3D model was established via Solidworks for modeling and Ansys for numerical simulation, the temperature field of the annular wear-resistant layer structure tuyere small sleeve with different widths of the wear-resistant layer was analyzed and compared with the temperature and stress field of traditional tuyere small sleeve. The results show that the design of the annular wear-resistant layer structure of the tuyere small sleeve is more effective. The new annular wear-resistant layer structure for the tuyere small sleeve results in a decrease of 24 K in the average temperature of the wear-resistant coating. The comparison of this structure with tuyere sleeves without wear-resistant coatings shows a 16.7% reduction in heat loss, improves the wear resistance of the tuyere, providing new technological ideas for low-carbon blast furnace production. Compared with the tuyere sleeve completely covered with a wear-resistant coating, the maximum thermal stress of this structure decreased from 624.98 Mpa to 427.99 Mpa, resulting in a reduction of 31.5%, which is beneficial for the service life of the tuyere sleeve. The copper surface temperature of the new tuyere small sleeve is in a safe range when the temperature is below 2273 K.

OBJECTIVES The aim was to evaluate the short-term outcomes of hybrid type II arch repair (HAR) and total arch replacement with frozen elephant trunk (TAR with FET) for acute DeBakey type I aortic dissection patients. METHODS From January 2017 to June 2019, the clinical data of acute DeBakey type I aortic dissection patients in a single centre were retrospectively reviewed; there were 92 cases of HAR and 268 cases of TAR with FET, with 56 pairs by propensity score matching. RESULTS After matching, the composite end points including 30-day mortality, stroke, paraplegia, renal failure, hepatic failure, reintubation or tracheotomy and low cardiac output syndrome were comparable (21.4%, 12/56 in the HAR group vs 21.4%, 12/56 in the TAR with FET group, P = 1.000). The rate of acute kidney injury (AKI) was significantly lower in the HAR group (58.9%, 33/56 vs 80.4%, 45/56, P = 0.031). The distribution of AKI stage according to the Kidney Disease Improving Global Outcomes criteria was different (P = 0.039), with more patients suffering from high-grade AKI in the TAR with FET group. Multivariable logistic analysis showed that the procedure type (HAR or TAR with FET) was not an independent predictor of composite adverse events or stroke. HAR was identified as a protective factor against AKI (odds ratio 0.485, 95% confidence interval 0.287–0.822; P = 0.007). CONCLUSIONS In the treatment of acute DeBakey type I aortic dissection, no significant differences were found in early outcomes between the 2 groups, but HAR was associated with a significantly lower incidence of AKI.