The influence of large foundation arrangement on underwater radiated noise of underwater vehicle engine compartment

Mechanical vibration is the main noise source of underwater vehicle. The foundation of the main power is an important pathway of mechanical noise. Large size foundation of the power not only affects the vibration transmitted from the power to the hull structure, but also affects the vehicle shell radiation area and radiation efficiency, thus affecting the radiation noise of underwater vehicle. Based on the study of the influence of the large size foundation arrangement on the radiated noise of underwater vehicles, two new types of foundation arrangement were proposed. The foundation could meet the requirements on the acoustic performance, and could greatly reduce the radiation surface area of the shell and reduce the radiated Sound Pressure. To the power compartment general layout and support function, three foundation layout schemes such as continuous style, large span style and bulkhead support style in the typical excitation of power equipment were designed. Further way, far field underwater radiation noise of the compartment was numerically calculated. The results show that bulkhead support style can effectively reduce underwater acoustic radiation of the compartment shell on the premise of the meet the weight control and impedance characteristics

Acute type A dissection without intimal tear in arch: Proximal or extensive repair?

ObjectiveFor acute type A dissection without an intimal tear in the arch, the optimal surgical strategy is unknown. The present study was designed to clarify the issue by comparing the early and late outcomes of proximal (PR) and extensive repair (ER).MethodsFrom January 2002 to June 2010, 331 patients with acute type A dissection were treated surgically at our institute. Of these 331 patients, 197 were identified without an arch tear on the preoperative imaging examination and by intraoperative inspection. Of these 197 patients, 74 underwent proximal repair, including the aortic root, ascending aortic, or hemiarch repair, and 88 underwent extensive repair, including proximal repair, total arch replacement and a stented elephant trunk technique. The perioperative variables and late results were statistically analyzed.ResultsNo significant difference was found in the rates of early mortality and morbidity between the 2 groups, despite the shorter duration of circulatory arrest in the PR group. During long-term follow-up (mean, 55.7 ± 33.1 months; maximum, 129), the overall survival rate in the whole cohort was 100%, 90.8%, and 71.1% at 1, 5, and 8 years, respectively. No difference was found in survival between the 2 groups (P > .05). However, complete thrombosis of the false lumen in the proximal descending aorta was achieved in 100% of the ER group and 24.6% of the PR group (P < .001). For patients with a patent false lumen in the PR group, distal anastomosis leakage and unclosed small intimal tears were identified in 53.3% and 35.6% patients, respectively. The reintervention rate was also lower in the ER group than in the PR group (4.9% vs 15.9%, P < .05) during follow-up. Moreover, the reintervention rate for patients with Marfan syndrome was 9.5% in the ER group and 38.5% in the PR group (P < .05).ConclusionsFor patients with acute type A dissection without an intimal tear in the arch, extensive repair could promote the occlusion of distal false lumen and decrease the reintervention rate without increasing the operative risk

Efficiency of different annuloplasty in treating functional tricuspid regurgitation and risk factors for recurrence

AbstractBackgroundFunctional tricuspid regurgitation (FTR) is frequent in patients with mitral valve disease. Untreated tricuspid regurgitation (TR) may cause poor clinical outcomes. The surgical factors involved in annuloplasty for FTR remain controversial. Our objective was to compare effectiveness of different tricuspid annuloplasty (TVP), and reveal the risk factors of recurrence.MethodsWe analyzed the clinical details of 399 consecutive patients who underwent mitral surgery with concomitant TVP, from 2006 to 2011, in two Chinese single-centers. Three methods were used for TVP: De Vega surgery was completed in 242 patients; annuloplasty using a flexible band was completed in 98 patients; and surgery with a rigid ring was performed in 59 patients.ResultsThe operative mortality rate was 2.3%. After surgery, the TR grade of all patients decreased significantly. At three years postoperatively, 13.7% of patients were diagnosed with recurrent FTR. At the three year time point, severe TR in the De Vega group was 18%, which was higher than those in the flexible (8.4%) and rigid planner ring groups (5.2%). During follow-up, the recurrent rates in the rigid group were significantly lower than in the flexible group. Multivariate analysis revealed that pre-operative atrial fibrillation, severe TR, large left atrial, ejection fraction (EF)<40%, De Vega annuloplasty, and postoperative permanent pacemaker installation were independent risk factors for severe recurrent TR.ConclusionsRigid ring annuloplasty efficaciously improved post-operative tricuspid valve function in patients with FTR. Atrial fibrillation, a large left atrium, low EF and postoperative permanent pacemaker installation were independent risk factors for severe recurrent TR

MicroRNA-30b is a multifunctional regulator of aortic valve interstitial cells

ObjectiveCalcific aortic valve disease is an active process involving a wide range of pathologic changes. Valve interstitial cells are the most prevalent cells in the heart valve and maintain normal valve structure and function. MicroRNAs (miRNAs) are essential posttranscriptional modulators of gene expression, and miRNA-30b is a known repressor of bone morphogenetic protein 2–mediated osteogenesis. We hypothesized that miRNA-30b is a multifunctional regulator of aortic valve interstitial cells during calcification.MethodsTo determine the role of miRNA-30b in calcific aortic valve disease, we evaluated miRNA expression in human calcific aortic valve leaflets obtained intraoperatively. Furthermore, human valve interstitial cells were evaluated with regard to miRNA-30b expression and osteogenesis by quantitative real-time polymerase chain reaction, Western blotting, flow cytometry, and alkaline phosphatase assays.ResultsIn this study, we demonstrated that miRNA-30b attenuates bone morphogenetic protein 2–induced osteoblast differentiation by targeting Runx2, Smad1, and caspase-3. Transfection of a mimic of miRNA-30b led to decreases in alkaline phosphatase activity and expressions of Runx2, Smad1, and caspase-3. Furthermore, dual luciferase reporter assays confirmed that Runx2, Smad1, and caspase-3 are direct targets of miRNA-30b.ConclusionsWe demonstrated a remarkable role of miRNA-30b in calcific aortic valve disease as a regulator of human aortic valvular calcification and apoptosis through direct targeting of Runx2, Smad1, and caspase-3. Targeting of miRNA-30b could serve as a novel therapeutic strategy to limit progressive calcification in aortic stenosis

All optical tunable RF filter using elemental antimony

In the past decade, the proliferation of modern telecommunication technologies, including 5G, and the widespread adoption of the Internet-of-things (IoT) have led to an unprecedented surge in data generation and transmission. This surge has created an escalating demand for advanced signal processing capabilities. Microwave photonic (MWP) processors offer a promising solution to satisfy this unprecedented demand for data processing by capitalising on the high bandwidth and low latency achievable by optical systems. In this work, we introduce an integrated MWP processing unit for all-optical RF filtering using elemental antimony. We exploit the crystallisation dynamics of antimony to demonstrate a photonic leaky integrator, which is configured to operate as a first-order low-pass filter with a bandwidth of 300 kHz and ultra-compact footprint of 16 × 16 μm2. We experimentally demonstrate the implementation of such a filter as an envelope detector to demodulate an amplitude-modulated signal. Finally, a discussion on achieving bandwidth tunability is presented