NUMERICAL INVESTIGATION OF AERODYNAMIC AND MIXING CHARACTERISTICS OF SCARFED LOBED MIXER FOR TURBOFAN ENGINE EXHAUST SYSTEM

The flow field and aerodynamic performances for the scarfed lobed forced mixer are studied based on a computational fluid dynamics（CFD） technique. A series of computations are conducted to obtain the effects of the bypass ratio and the scarf angle on the mixing performance for the scarfed lobed mixer. Results show that the scarfed lobed mixer is reduced in the system weight. Meanwhile, aerodynamic performances are slightly improved compared with the normal lobed mixer. Two reasons for causing the mixing enhancement between the core and the bypass flow are as follows： （1） The stream-wise vortices shed from the training edge of the half/full scarfed lobed mixer earlier is enhanced by about 25%. （2） The mixing augmentation is also associated with the increase of the interface length caused by scarfing. The thermal mixing efficiency is enhanced with the increase of the bypass ratio and the scarfing angle. The scarfed lobed mixer design has no negative effects on the pressure loss. The total pressure recovery coefficient reaches above 0. 935 in various bypass ratios and scarfed angles. As the bypass ratio increases, the total pressure recovery coefficient also increases for the scarfed lobed mixer.

地税局:任重而道远——省地税局局长吴碧莲(左图)谈话摘要

□1994年,我省地方税务局在改革中誕生。經過一年運作,新舊體制平穩過渡,省地縣三級地稅機構已經建立,員工總數達到5800多人,干部培訓亦已結束,地稅業務全面啟動,地税稅源的調查摸底方興艾未,年内地稅稅收任務超額完成。

Lung tissue flap repairs esophagus defection with an inner chitosan tube stent

AIM： TO repair the partial esophagus defect with a chitosan stent, a new esophageal prosthesis made of pulmonary tissue with vascular pedicie.METHODS： Fifteen Japanese big ear white rabbits were divided into experimental group （n = 10） and control group （n = 5）. Esophagus defect in rabbits of experimental group was repaired using lung tissue flap with a chitosan tube stent, gross and histological appearance was observed at week 2, 4 and 8 after operation, and barium sulphate X-ray screen was performed at week 10 after operation. Esophagus defect of rabbits in control group was repaired using lung tissue flap with no chitosan tube stent, gross and histological appearance was observed at week 2, 4 and 8 after operation, and barium sulphate X-ray screen was performed at week 10 after operation.RESULTS： In the experimental group, 6 rabbits survived for over two weeks, the lung tissue flap healed esophageal defection, and squamous metaplasia occurred on the surface of lung tissue flap. At week 10 after operation, barium sulphate examination found that barium was fluent through the esophagus with no stricture or back stream, the creeping was good. In the control group, 4 rabbits survived for two weeks, the lung tissue flap healed esophageal defection with fibrous tissue hyperplasia, barium sulphate examination found that barium was fluent through the esophagus with a slight stricture or back stream, and the creeping was not good at week 10 after operation.CONCLUSION： Esophagus defect can be repaired using lung tissue flap with an inner chitosan tube stent.

Transcatheter aortic valve replacement in elderly patients

Aortic stenosis is the most common native valve disease, affecting up to 5% of the elderly population. Surgical aortic valve replacement reduces symptoms and improves survival, and is the definitive therapy in patients with symptomatic severe aortic stenosis. However, despite the good results of classic surgery, risk is markedly increased in elderly patients with co-morbidities. Transcatheter aortic valve replacement （TAVR） allows implantation of a prosthetic heart valve within the diseased native aortic valve without the need for open heart surgery and cardiopulmonary bypass, offering a new therapeutic option to elderly patients considered at high surgical risk or with contraindications to surgery. To date, several multicenter registries and a randomized trial have confirmed the safety and efficacy of TAVR in those patients. In this chapter, we review the background and clinical applications of TAVR in elderly patients.

EXPRESSION AND ROLE OF PLASMINOGEN SYSTEM IN PROCESS OF RESTENOSIS

Objective To study the expression and role of plasminogen system in the process of restenosis. Methods We established a double-injury model of atherosclerotic restenosis in rabbit iliac artery mimicking human arterial restenosis. The time course of tissue plaminogen activator (tPA), urokinase plasminogen activator (uPA), urokinase plasminogen activator receptor (uPAR) and plasminogen activator inhibitor-1 (PAI-1) was investigated by immunohistochemistry. The mRNA expression of uPA and uPAR were detected after vascular procedures by in situ hybridization. Results In uninjured arteries, the weak expression of tPA and PAI-1 was detected in intimal and endothelial cells. The expression of tPA, uPA, uPAR and PAI-1 was significantly induced after double-injury, but after double-injury 14d, the expression of tPA restore to preinjury levels. The expression of uPA and uPAR in intimal was higher than that of media and maintain high levels in intimal within 42d and 56d. Conclusion Whereas t-PA is primarily involved in clot dissolution and play a limited role in the process of restenosis, in plasminogen system, uPA and uPAR play a prominent role in the process of restenosis.

Anteroposterior cricoid split interposition costal cartilage grafts for laryngotracheal stenosis in children

Objective: To investigate the effects of anteroposterior cricoid spliting interposition costal grafting for moderate and severe laryngotracheal stenosis in children. Methods: From 1995 to 2005, 87 children (aged 1. 2 to 14 years) with moderate and severe glottic and subglottic stenosis were retrospectively studied. They were operated with cricoid spliting laryngotracheal reconstruction in our hospital. All of 87 patients were tracheostomy-dependent before surgery. Results: Eighty-five patients (95%) were successfully decannnulated and got an effective phonation. The follow-up time was more than 5 years. The effect of operation was satisfactory and the growth and development of children was normal. Conclusion: Anteroposterior cricoid split interposition costal cartilage graft is a safe and effective treatment method for moderate and severe glottic and subglottic stenosis in children.

Vascular endothelial growth factor gene transfer improves host endothelialization of xenogeneic biologic heart valve in vivo

OBJECTIVE: To investigate the feasibility of endothelialization of bioprosthesis by transfer of vascular endothelial growth factor (VEGF) gene. METHODS: Bovine pericardium treated with glutaraldehyde and L-glutamic acid was positioned into the pig right atrium. pcD(2)/hVEGF(121) gene (1 mg) was transferred into the right ventricular myocardium using surgical sutures Reverse transcri ption polymerase chain reaction (RT PCR) was employed to evaluate the expression of myocardial VEGF mRNA. The determination of concentrations of VEGF protein in blood from both the right atrium and peripheral vein, and histological and ultrastructural analysis of implanted bovine pericardium were completed simultaneously. RESULTS: The concentration of VEGF derived from the right atrium in pcD(2)/hVEGF(121) group was significantly higher than that in the pcD(2) group 10 days after VEGF gene transfer (P

唱响创业成才主旋律——团结带领进京青年为首都现代化建设做贡献

近期,北京團市委、北京市外管辦、首都文明辦、首都綜治辦、北京市建委、北京市社區辦、北京市勞動和社會保障局、北京市工商局、北京市計生委、北京青年報社等單位聯合開展了第四届北京市“ 十佳(優秀)進京創業青年評選活動,在全市300餘萬外地進京創業的青年中激起了强烈的反響。

Evaluation of the safety and efficacy of transcatheter aortic valve implantation in patients with a severe stenotic bicuspid aortic valve in a Chinese population

Objective： The purpose of this study is to evaluate the safety and efficacy of transcatheter aortic valve implantation （TAVI） in patients with a severe stenotic bicuspid aortic valve （BAV） in a Chinese population. While several groups have reported the feasibility, efficacy, and safety of TAVI for patients with a BAV, worldwide experience of the technique is still limited, especially in China. Methods： From March 2013 to November 2014, high surgical risk or inoperable patients with symptomatic severe aortic stenosis （AS） who had undergone TAVI at our institution were selected for inclusion in our study. Results were compared between a BAV group and a tricuspid aortic valve （TAV） group. Results： Forty patients were included in this study, 15 （37.5%） of whom were identified as having a BAV. In the BAV group, the aortic valve area was smaller （（0.47±0.13） vs. （0.59±0.14） cm2）, the ascending aortic diameter was larger （（40.4±4.4） vs. （36.4±4.3） mm）, and the concomitant aortic regurgitation was lower. No significant differences were found between the groups in the other baseline characteristics. No differences were observed either in the choice of access or valve size. The procedural success achieved in this study was 100%. There were no differences between groups in device success （86.7% vs. 88.0%）, 30-d mortality （6.7% vs. 8.0%）, or 30-d combined end point （13.3% vs. 12.0%）. The incidences of new pacemaker implantation, paravalvular regurgitation and other complications, recovery of left ventricle ejection fraction and heart function were similar in both groups. Conclusions： Patients with a severely stenotic BAV can be treated with TAVI, and their condition after treatment should be similar to that of people with a TAV.

Bispectral index-guided sedation in transfemoral transcatheter aortic valve implantation:a retrospective control study

Objective： Transcatheter aortic valve implantation （TAVI） is a minimally invasive therapy for elderly patients with severe aortic valve stenosis who were refused surgical aortic valve replacement because of the high perioperative risk. Traditionally, this procedure has been done under general anesthesia, but more recently local anesthesia and sedation have become popular. This research assessed the effectiveness of transfemoral TAVI under bispectral index （BIS）-guided sedation. Methods： In this single-center retrospective control analysis, clinical data, including demographic characteristics, echocardiography, periprocedural data, and main complications, were collected and assessed in 113 patients undergoing TAVI through the femoral artery under general anesthesia （GA group, n=36） and under BIS-guided sedation （SED group, n=77）. Results： The demographic characteristics and echocardi-ographic parameters between the two groups were similar （P〉0.05）. Two （2.6%） of patients were moved from BIS-guided sedation to general anesthesia for surgical reasons. Procedures were significantly shorter in the SED group than in the GA group （（127.10±44.43） min vs. （165.90±71.62） min, P=0.004）. Patients in the SED group lost less blood and received significantly fewer red blood cells and catecholamines than those in the GA group （5.19% vs. 22.22%, P=0.017 and 67.53% vs. 97.22%, P〈0.001）. The length of hospital stay was significantly shorter and there were fewer pulmonary complications in the SED group than in the GA group. Thirty-day mortality was similar between the two groups. Conclusions： BIS-guided sedation is a feasible and safe approach for transfemoral TAVl. The anes- thesiologist should choose the best anesthetic method according to the team＇s experience.

A simple skin flap plasty to repair tracheocutaneous fistula after tracheotomy

The tracheocutaneous fistula after tracheostomy is a complex clinical problem. An ideal fistula closure is still difficult at present though a variety of fistula-closing methods have been reported in the literature. We used a turnover skin flap to cover the fistula. All the procedures were completed at bedside under local anesthesia. The fistula was successfully closed and well healed without complications within 7-9 days. It has been proven that this operation is simple, effective, and safe.

Free flap transfer bridged by antegrade and retrograde posterior tibial vessel flaps temporally borrowed from the healthy leg

Objective: To study the methods and techniques of free flap transfer bridged by posterior tibial vascular flap in treating large soft tissue defects in low limbs without usable recipient blood vessels. Methods: Based on morphological observation and measurement of arterial pressure and blood flow, an antegrade and a retrograde vascular bridge flaps were designed using the healthy posterior tibial vessels to serve as vascular pedicles to carry two free flaps for transplantation. Results: Eight cases of patient with one or two large soft tissue defects in the leg region were treated by the method. All the bridge flaps and free flaps survived well, and the defects were repaired completely. Conclusions: The results showed that it is an ideal method for using the posterior tibial vessels from the healthy limb to form vascular pedicles in repairing large soft tissue defects in patients without a usable recipient blood vessel.