Valley polarization and photocurrent generation in transition metal dichalcogenide alloy MoS2x_{2x}Se2(1−x)_{2(1-x)}

Monolayer transition metal dichalcogenides (TMDCs) constitute the core group of materials in the emerging semiconductor technology of valleytronics. While the coupled spin-valley physics of pristine TMDC materials and their heterstructures has been extensively investigated, less attention was given to TMDC alloys, which could be useful in optoelectronic applications due to the tunability of their band gaps. We report here our experimental investigations of the spin-valley physics of the monolayer and bilayer TMDC alloy, MoS$_{2x}$Se$_{2(1-x)}$, in terms of valley polarization and the generation as well as electrical control of a photocurrent utilising the circular photogalvanic effect. Piezoelectric force microscopy provides evidence for an internal electric field perpendicular to the alloy layer, thus breaking the out-of-plane mirror symmetry. The experimental observation is supported by first principles calculations based on the density functional theory. A comparison of the photocurrent device, based on the alloy material, is made with similar devices involving other TMDC materials

Three dimensional rotational angiography imaging of double aortic arch vascular ring

Three dimensional (3D) rotational angiography is a technique used increasingly for imaging in congenital heart disease. Here the use of this technique for imaging of double aortic arch vascular ring is described and the advantages of this modality. are discussed. 3D rotational angiography is an excellent tool for imaging of various vascular anomalies. It provides high quality accurate images through a quick and safe procedure.peer-reviewe

Constant Site Hemodialysis in the Pediatric Population: Successful use of VWINGs in Three Patients

Introduction: Reliable vascular access for hemodialysis is challenging in the pediatric population. The Venous Window Needle Guide (VWING; Vital Access Corp, Salt Lake City, Utah) is an implanted surgical device that allows for constant site access but has not been reported in pediatric patients. Case description: Three patients under 18 years of had a brachiobasilic fistula created with a minimum of 6 weeks for fistula maturation prior to VWING placement. This paper describes the management of constant site dialysis using VWING as well as strategies used for successful long-term management. Patients include a 15-year-old male with end-stage renal disease (ESDR) secondary to hemolytic uremic syndrome (HUS), a 14-year-old female with ESRD secondary to systemic lupus, and a 17-year-old female with ESRD secondary to rapidly progressive glomerulonephritis. All three patients had successful placement of VWING allowing for improved AVF access for dialysis for several years. Conclusion: In our limited experience with VWINGs in the pediatric population, we have demonstrated a successful method of long-term constant-site dialysis using VWING as an adequate alternative to other interventions for difficult-to-access arteriovenous fistulas (AVFs)

Extracorporeal membrane oxygenation in postcardiotomy patients: Factors influencing outcome

ObjectiveOur objective was to assess the morbidity and mortality in children requiring extracorporeal membrane oxygenator support after cardiac surgery and to determine factors influencing outcome.MethodsBetween January 2003 and June 2008, 58 patients required extracorporeal membrane oxygenator support after cardiac surgery. A retrospective study was performed and factors influencing outcome were determined by logistic regression modeling with the probability of outcome based on a combination of multivariate predictors.ResultsMedian age and weight were 12 days and 3.3 kg, respectively. Thirty-one patients had single ventricle repair and 27 had biventricular repair. Median duration of support with the oxygenator was 6 days. Thirty-nine (67%) patients were successfully weaned off the support, but only 24 (41%) survived to hospital discharge. Chief complications were renal failure (31%), neurologic complications (29%), and sepsis (16%). Multivariable logistic regression analysis identified 10 days or more of extracorporeal membrane oxygenation (odds ratio = 6.1), urine output less than 2 mL · kg−1 · h−1 in first 24 hours (odds ratio = 15), renal failure (odds ratio = 9.4), and pH less than 7.35 after 24 hours of extracorporeal membrane oxygenation (odds ratio = 82) as significant independent factors associated with failure to wean off extracorporeal membrane oxygenation. Factors associated with failure of hospital discharge despite successful decannulation were as follows: extracorporeal membrane oxygenator support time of 10 days or more, red blood cell transfusion of greater than 1000 mL/kg during the entire period of oxygenator support, and sepsis. Patients with single ventricle repair were at higher risk of hospital mortality.ConclusionLonger duration of extracorporeal membrane oxygenator support, low pH and urine output in the first 24 hours, and renal failure are significant factors associated with mortality during extracorporeal membrane oxygenator support. Exposure to high amounts of blood transfusion during extracorporeal oxygenation, extended extracorporeal membrane oxygenator support, and sepsis increase risk of death after successful decannulation

Severe tricuspid valve stenosis secondary to pacemaker leads presenting as ascites and liver dysfunction: A complex problem requiring a multidisciplinary therapeutic approach

Tricuspid stenosis secondary to ventricular pacemaker leads is uncommon. We present a unique case of iatrogenic tricuspid stenosis secondary to fusion of the valve leaflets to transvenous implanted pacing leads. This occurred in an adult with childhood repaired Tetralogy of Fallot and high grade surgical heart block following multiple pacemaker procedures. The case was complicated by superior vena cava (SVC) and innominate vein stenosis secondary to implanted pacing leads, severe tricuspid valve (TV) stenosis, perforation of the heart by one of the implanted transvenous ventricular pacing leads, prolapse of the transvenous atrial pacing lead into the right ventricle, and unusual coronary sinus anatomy. We describe a multidisciplinary approach to management. © Springer Science+Business Media, LLC 2008