导通瞬态时续流二极管(FWD)反向恢复现象

研究IGBT模块中续流二极管 (FWD)导通脉冲宽度 (tw)很小时的反向恢复现象。通过仿真测得这种极限工作状态下FWD的电流、电压有关波形 ,对波形分析可得知导通脉冲宽度 (tw)很小时的反向恢复是导致芯片损坏的原因。

Transit Properties of High Power Ultra\|Fast Photoconductive Semiconductor Switch

Experiments of a GaAs ultra\|fast Photo\|Conductive Semiconductor Switch (PCSS) are reported. Both the linear and nonlinear modes were observed when triggered by the μJ nano\|second laser. The peak current could be as high as 560A. The rise time of the current pulse responses is less than 200ps when triggered with 76MHz femto\|second laser.

NOVEL CELESTIAL NAVIGATION FOR SATELLITE USING X-RAY PULSARS

The X-ray pulsar-based navigation is a novel technology for the satellite autonomous navigation. The position and the velocity of the satellite are deterimined by using the pulse phases detected at the satellite and predicted by the pulse timing models. With the detected pulse phase, the satellite position with respect to the Earth center can be calculated along the line-of-sight to the pulsar. Using three pulsars, the satellite position in the in- ertial frame can be resolved. The extended Kalman filter （EKF） algorithm is designed to incorporate the range measurements with the satellite dynamics. Simulation verification shows that the proposed algorithm can accu- rately determine the satellite orbit, with the position error less than 100 m. Furthermore, the factors influencing the navigation performance are also discussed.

多电平逆变电路及相关问题分析

在简要介绍了电压型三相逆变电路的基础上,着重阐述了多电平逆变电路中常用的三电平逆变电路的工作原理,并结合脉宽调制技术(PWM)讨论了电路中遇到的问题及对策。

Transcatheter to Close the Patent Duetus Arteriosus and Atrial Septal Defects in Children

Objective: To evaluate the therapeutic effect, safety and complications oftranscathetering Amplatzer device in the closure of patent ductus arteriosus (PDA) and atrial septaldefects (ASD) in children. Methods: Patients with PDA (n = 25) and ASD ( n = 16), confirmed byechocardiography, were treated by transcatheterization. Amplatzer occluder device was placed by thetranscatheterization with the image support of X-ray and transthoracic echocardiography ( TTE) . TheTTE, ECG and X-ray examination were engaged to evaluate the therapeutic results on the time pointsof 24 h , 1, 3 , 6, 12 months after the operation, and all these cases were engaged to the follow-upexamination. Results: The cardioangiographic diameter was 13.0-28.0 mm ([19.3+-4.9] mm) in ASD and2.0-7.7 mm ([3.9+-1.5] mm) in PDA . The diameter of the Amplatzer occluder selected were 13.0-30.0mm ( [20.6+-5.1] mm) in ASD and 4.0-12.0 mm ([6.6+-1.9] mm) in PDA , respectively. All the Amplatzeroccluders were placed successfully. There were no complications during and after the operation.Very small residual shunt was still found soon after the operation in 10 cases , and there were noresidual or recanalization after three months of the operation. The pulmonary artery pressure andheart size were significantly decreased in follow-up examination . Conclusion: Transcatheteringclosure with Amplatzer device is an effective, simple and safe technique in the treatment of ASD andPDA in children.

Branched-chain amino acid treatment before transcatheter arterial chemoembolization for hepatocellular carcinoma

AIM： To examine the significance of branched-chain amino acid （BCAA） treatment before transcatheter arterial chemoembolization （rACE） for hepatocellular carcinoma （HCC）.METHODS： This study included 99 patients who underwent TACE therapy for HCC at our hospital and were followed up without treatment for at least 6 mo between January 2004 and January 2010. They were divided into 2 groups： those receiving BCAA granules （/7 = 40） or regular diet （n = 59, control）. Data obtained were retrospectively analyzed （prior to TACE, and 1 wk, 1, 3, and 6 mo after TACE） in terms of nutritional condition and clinical laboratory parameters （serum albumin level and Child-Pugh score）, both of which are determinants of hepatic functional reserve.RESULTS： The BCAA group comprised 27 males and 13 females with a mean age of 69,9 ：E 8,8 years, The patients of the BCAA group were classified as follows： Child-Pugh A/B/C in 22/15/3 patients, and Stage Ⅱ/Ⅲ/ /IVA HCC in 12/23/5 patients, respectively. The controlgroup comprised 32 males and 27 females with a mean age of 73.2 ± 10.1 years. In the control group, 9 patients had chronic hepatitis, Child-Pugh A/B/C in 39/10/1 patients, and Stage Ⅰ/Ⅱ/Ⅲ/IVA HCC in 1/11/35/12 patients, respectively. Overall, both serum albumin level and Child-Pugh score improved significantly in the BCAA group as compared with the control 3 and 6 mo after TACE （P 〈 0.05）. Further analysis was performed by the following categorization： （1） child-Pugh classification; （2） liver cirrhosis subgroup with a serum albumin level 〉 3.5 g/dL; and （3） epirubicin dose. A similar trend indicating a significant improvement of all variables in the BCAA group was noted （P 〈 0.05）.CONCLUSION： Treatment with BCAA granules in patients who have undergone TACE for HCC is considered useful to maintain their hepatic functional reserve.

Cerebral and pulmonary embolisms after transcatheter arterial chemoembolization for hepatocellular carcinoma

A cerebral lipiodol embolism is an extremely rare complication of transcatheter arterial chemoembolization for hepatocellular carcinoma. We present a case of cerebral lipiodol embolism that occurred after the third arterial chemoembolization, report the clinical and radiological findings, and review the medical literature.

Gain Switch of an AlGaInP Red Light Semiconductor Laser Diode

We solve the single mode coupled rate equations by computer,simulate the behavior of a gain switch of an AlGaInP red light semiconductor laser diode,and find the characteristic of FWHM of pulses changing with the amplitude of modulation signal, the bias current, and the modulated frequency. On this basis, we conduct experiments. The experiment results accord with the simulations well.

Pulmonary embolism after transcatheter arterial chemoembolization for hepatocellular carcinoma:a retrospective analysis on 10 years' experience

To study the clinical characteristics and treatment of pulmonary embolism （PE） after transcatheter arterial chemoembolization （TACE） for hepatocellular carcinoma （HCC）. Methods： The clinical records of 13 512 patients diagnosed with HCC and received TACE from January 2000 to December 2009 were reviewed. Among these patients, 5 031 were allocated into group A who had one or more disorders like diabetes, hypertension, coronary heart disease, obesity or varicose vein of lower limb, while the other 8 481 patients who did not have such disorders were in group B. Results： A total of 39 185 TACE procedures were performed for the 13 512 patients. Five （0.01%） patients in group A developed PE after TACE, of whom two recovered 4 and 5 d later with early anticoagulant therapy while the hypertension, coronary heart disease, obesity or varicose vein of lower limb are possibly more likely to develop PE other 3 died of respiratory failure within 5 h. The mortality of PE was 60% （3/5）. Conelusion： HCC patients with diabetes, after TACE than those without such disorders. Patients who have such disorders should be more carefully observed after TACE and early treatment with heparin should be applied once PE develops.

Optical-field-induced memory effect of nematic liquid crystal doped with zinc porphyrin dimers

In this paper, the optical-field-induced reorientation ofnematic liquid crystal （5CB） doped with a volume fraction of 1.0% of zinc porphyrin dimers ο, ο-C2-（L-Thr）-C2-（TPP）2Zn（II）2 has been studied. Excited by 1.06 lain, YAG laser pulse with 10 ns pulse duration and 100 mJ pulse energy, both of the doped 5CB and pure 5CB perform the reorientation. When the exciting laser pulse withdraws, the doped 5CB retains the reorientation and without back to the initial orientation, and the memory effect is formed accordingly, whereas the pure 5CB relax to the initial orientation. A model considering the intermolecular coupling change between the dopant and host 5CB, and together with the aligning surface adsorption process of deformed dopant are present to explain this memory effect. In order to prove this mechanism, 5CB doped with another dopant （zinc porphyrin, ZnTPP） was used for contrast, which induces no such memory effect. This phenomenon is very useful to study the optical data storage and memory display.

Evaluation of CA125 and NT-proBNP values in patients undergoing transcatheter aortic valve implantation

Background Transcatheter aortic valve implantation （TAVI） is a minimally invasive, emerging therapy in surgically high risk, or in- operable patients. Parameters used for risk classification have some deficiencies in the selection of patients. The objective of this study is to evaluate the impact of TAVI on carbohydrate antigen 125 （CA125） and N-terminal pro brain-type natriuretic peptide （NT-proBNP） as biomarkers that have been used frequently in recent years, and also the relationship of these biomarkers to prognosis. Methods ＆ Results Transcatheter aortic valve implantation was practiced on 31 patients in this study. Then, CA125 and NT-proBNP levels studied in patients prior to and after the TAVI were evaluated. The patients were also grouped in accordance with their left ventrieular ejection fraction （LVEF） and CA125 levels （LVEF 〉 40% and 〈 40%; CA125 ≤ 35 U/L and 〉 35 U/L）. The TAVI operation was successfully performed in all patients. There was no in-hospital mortality and substantial improvement in functional capacity was detected at follow ups. In addition, a statistically significant decrease was detected in post-TAVI CA 125 and NT-proBNP levels of all patients （CA 125 83.8 ± 18.1 U/L vs. 64.3 ±14.2 U/L, P = 0.008; NT-proBNP： 4633.6± 627.6 pg/mL vs. 2866.3±536.8 pg/mL, P 〈 0.001）. In groups divided according to the CA125 levels, there was also statistically significant post-TAVI decline in CA125 levels. Within CA125 〉 35 U/L and LVEF 〈 40% groups, the permanent need for a pacemaker was required in one （3.2%） patient and mortality was observed in two （6.4%） patients after TAVI at follow up. Conclusions The results show that TAVI can be performed effectively and reliably in patients with high baseline levels of CA125 and NT-proBNP. These biomarkers are reduced substantially with TAVI, while high biomarker levels are associated with undesired events, and certainly, these biomarkers can be used for risk classifications in patient selection for TAVI.

Advanced age and the clinical outcomes of transcatheter aortic valve implan-tation

Aortic valve stenosis （AS） is common in the elderly. Although surgical replacement of the valve has been the gold standard of management, many patients have been excluded from surgery because they were very old, frail, or had co-morbidities that increased operative risks. In the last decade, transcatheter aortic valve implantation （TAVI） has emerged as a new treatment option suitable for these patients. This article reviews the available literature on the role of TAVI in elderly patients with severe aortic stenosis. Published studies showed that elderly individuals who underwent TAVI experienced better in-hospital recovery, and similar short and mid-term mortality compared to those underwent surgical treatment of AS. However, long-term outcomes of TAVI in elderly patients are still unknown. The available data in the literature on the ef-fect of advanced age on clinical outcomes of TAVI are limited, but the data that are available suggest that TAVI is a beneficial and tolerable procedure in very old patients. Some of the expected complications after TAVI are reported more in the oldest patients such as vascular in-jures. Other complications were comparable in TAVI patients regardless of their age group. However, very old patients may need closer monitoring to avoid further morbidities and mortality.

Self-magnetism and Persistent Photoconductivity

Persistent photoconductivity has been investigated by various models, among which the Macroscopic Barrier model, Large-Lattice-Relaxation model, and Random Local Potential Fluctuations model are mostly well known. Although the three well-known models have played important roles in describing the persistent photoconductivity, they are not the principal cause of persistent photoconductivity. In this paper a classical model originated from ＂selfmagnetism of electron gas＂ is proposed to illustrate the persistent photoconductivity phenomenon. This classical model is based on electron gas pulsation, which depends on the charge density. Different concentrations of current carriers create different frequencies in the system, and thus the system is sensitive to different wave lengths of incident light. Then the construction of different detectors can be possible for different wave lengths of incident light.

Gene cloning and induced expression pattern of IRF4 and IRF10 in the Asian swamp eel(Monopterus albus)

The Asian swamp eel （Monopterus albus） is one of the most economically important freshwater fish in East Asia, but data on the immune genes of M. albus are scarce compared to other commercially important fish. A better understanding of the eel＇s immune responses may help in developing strategies for disease management, potentially improving yields and mitigating losses. In mammals, interferon regulatory factors （IRFs） play a vital role in both the innate and adaptive immune system; though among teleosts IRF4 and IRFIO have seldom been studied. In this study, we characterized IRF4 and IRFIO from M. albus （malRF4 and malRFlO） and found that malRF4 cDNA consists of 1 716 nucleotides encoding a 451 amino acid （aa） protein, while malRFlO consists of 1 744 nucleotides including an open reading frame （ORF） of 1 236 nt encoding 411 aa. The malRFlO gene was constitutively expressed at high levels in a variety of tissues, while malRF4 showed a very limited expression pattern. Expression of malRF4 and malRFlO in head kidney, and spleen tissues was significantly up-regulated from 12 h to 48 h post-stimulation with polyinosinic： polycytidylic acid （poly I：C）, lipopolysaccharide （LPS） and a common pathogenic bacteria Aeromonas hydrophila. These results suggest that IRF4 and IRF10 play roles in immune responses to both viral and bacterial infections in M. albus.

Novel treatment of coronary artery fistulae concealing severe coronary artery lesion： using thrombus aspiration catheter as a delivery guide

In this case report, we present the occlusion of multiple coronary artery fistulaes originating from proximal left anterior descending （LAD） and fight sinus valsavla and empting to the pulmonary artery at the same place. We occluded LAD fistulae by using thrombus aspira- tion catheter as a delivery guide. To the best of our knowlege, this is the first case of occlusion of coronary fistulaes with the help of throm- bus aspiration catheter. Our experience may suggest that thrombus aspiration catheters can be used in treating coronary artery fistulaes with difficult anotomv.

Transcatheter aortic valve implantation in 2015

The last decade has seen transcatheter aortic valve implantation （TAVI） emerge as the standard of care for patients with severe symptomatic aortic stenosis deemed to be either at excessiveor high-risk for surgical aortic valve replacement （SAVR）. This position is supported by three important multicentre randomized trials comparing TAVI to the historical gold standard therapies： （1） The Placement of AoRTic TraNscathetER Valve Trial Edwards SAPIEN Transcatheter Heart Valve （PARTNER） IB Trial compared TAVI （Edwards SAPIEN, Edwards Lifesciences Inc., Irvine, CA） to optimal medical therapy in patients at excessive surgical risk, and demonstrated an absolute mortality reduction of 〉 20% at 1-year, an effect that was maintained out to 5-year follow-up;Ill （2） The PARTNER 1A Trial compared TAVI （Edwards SAPIEN, Edwards Lifesciences Inc.,

Peripherally inserted central catheters in critically ill patients-complications and its prevention:A review

Peripherally inserted central catheter(PICC)is extensively used in critical care settings,because it plays a vital role in providing safe central venous entry.However,PICC is associated with several complications,which should be detected to shorten the duration of patients'improvement,reduce health care cost,and lessen the incidence of various PICC-related complications.Therefore,this study aimed to outline current literature on PICC procedures,potential complications,and measures for prevention.Understanding evidence-based guidelines regarding insertion technique,early detection of complications,and care bundle of PICC is significant in complication prevention.Implementation of education,training,and appropriate multidisciplinary approaches on PICC care among nurses and caregivers is the key to preventing complications.Thus,the strict care of indwelling PICC lines,the targeted and reasonable PICCassociated complication prevention,and nursing care have a major clinical significance in reducing the occurrence of potential PICC complications.

Role of transcatheter arterial embolization for massive bleeding from gastroduodenal ulcers

Intractable bleeding from gastric and duodenal ulcers is associated with significant morbidity and mortality. Aggressive treatment with early endoscopic hemostasis is essential for a favourable outcome. In as many as 12%-17% of patients,endoscopy is either not available or unsuccessful. Endovascular therapy with selective catheterization of the culprit vessel and injection of embolic material has emerged as an alternative to emergent operative intervention in high-risk patients. There has not been a systematic literature review to assess the role for embolotherapy in the treatment of acute upper gastrointestinal bleeding from gastroduo-denal ulcers after failed endoscopic hemostasis. Here,we present an overview of indications,techniques,and clinical outcomes after endovascular embolization of acute peptic-ulcer bleeding. Topics of particular relevance to technical and clinical success are also discussed. Our review shows that transcatheter arterial embolization is a safe alternative to surgery for massive gastroduodenal bleeding that is refractory to endoscopic treatment,can be performed with high technical and clinical success rates,and should be considered the salvage treatment of choice in patients at high surgical risk.