Rolling ferrofluid drop on the surface of a liquid

We report on the controlled transport of drops of magnetic liquid, which are swimming on top of a non-magnetic liquid layer. A magnetic field which is rotating in a vertical plane creates a torque on the drop. Due to surface stresses within the immiscible liquid beneath, the drop is propelled forward. We measure the drop speed for different field amplitudes, field frequencies and drop volumes. Simplifying theoretical models describe the drop either as a solid sphere with a Navier slip boundary condition, or as a liquid half-sphere. An analytical expression for the drop speed is obtained which is free of any fitting parameters and is well in accordance with the experimental measurements. Possible microfluidic applications of the rolling drop are also discussed

Evidence that Statins Protect Renal Function During Endovascular Repair of AAAs

Objectives: Several studies have documented a slight but significant deterioration of renal function after endovascular repair of abdominal aortic aneurysm (AAA) (EVAR). The aim of this retrospective study was therefore to investigate whether medication with statins may favourably affect perioperative renal function. Material and Methods: From January 2000 to January 2008, out of a total cohort of 287 elective patients receiving endovascular repair of their AAA or aortoiliac aneurysm, 127 patients were included in the present study, as their medication was reliably retrievable. Patients were divided according to whether their medication included statins (>3 months). Second, they were subdivided according to their supra- (SR) or infrarenal (IR) endograft fixation. Serum creatinine (SCr) and creatinine (CrCl) clearance were determined preoperatively, postoperatively, at 6 and 12 months. Patients with known pre-existing renal disease, with incorrect placement of the stent graft resulting in severe renal artery stenosis, and with occlusion or renal parenchymal infarction were excluded from the study. Results: Patients receiving an infrarenal fixation of their graft had no change in the renal function, regardless whether they were on statins or not. In patients with SR fixation not receiving statins, a deterioration in renal function was observed in the early postoperative period ((SCr) preoperative vs. SCr postoperative: 1.02 +/- 0.2 vs. 1.11 +/- 0.28, p < 0.001 and (Cr.Cl) preoperative vs. Cr.Cl postoperative: 74.1 +/- 21.4 vs. 68.0 +/- 21.4, p<0.001), whereas patients on statins experienced no change in renal function (SCr preoperative vs. SCr postoperative: 0.99 +/- 0.24 vs. 1.02 +/- 0.20 n.s. and Cr.Cl preop vs. Cr.Clpostop.: 76.4 +/- 19.1 vs. 74.28 +/- 20.50, n.s.). During follow-up, a constant worsening of renal function at 6 and 12 months was observed, irrespective of the medication with statins. Conclusions: The present study suggests a slight immediate deterioration of the renal function using (SR) fixation, and this could be prevented by the use of statins. During follow-up, statins did not protect from further renal deterioration. Broader studies are needed to confirm a definitive relation between statin use and renal protection during the endovascular repair of AAA. (C) 2010 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved

A Modified Approach of Proximalization of Arterial Inflow Technique for Hand Ischemia in Patients with Matured Basilic and Cephalic Veins

Objective: Proximalization of arteriovenous inflow (PAI) is an established technique for treating patients with access-induced hand ischemia. However, a prosthetic graft, used as arterial inflow, could minimize the benefits of a purely native fistula. In this study, a new PAI technique is reported, which avoids the use of prosthetic grafts in patients with matured basilic and cephalic veins. Patients and methods: Eight patients (seven men, one woman; mean age 62 (45-82) years old) with grade III/IV critical dialysis access-related ischemia (DARI) and with a pre-existing Gracz fistula underwent an operation using modified PAI. The basilic and cephalic veins were preoperatively matured. During the operation, the former arteriovenous anastomosis was closed and the basilic vein was used as arterial inflow. Results: All procedures were technically successful. All patients but one could be discharged with a warm, neurologically improved extremity with a significant reduction in pain. After a mean follow-up of 43.5 (0-52) months, there were no recurrent steal symptoms and all necrotic hand lesions healed. Two patients died during the follow-up, but with well-functioning fistulae. One fistula failed during follow-up and one further fistula was ligated because of chronic neurological damage, which was not improved after the PAI procedure. Four AVFs are still available for hemodialysis. Conclusions: The modification of the PAI technique with a basilic vein as presented here showed similar results to the original PAI procedure. This new procedure does not require prosthetic grafts as in the original PAI technique or a central venous catheter and leads to the enlargement of the puncture site as a result of the superficialization of the basilic vein. Therefore, it is believed that this new technique could be a good option for those patients with matured cephalic and basilic veins who suffer from severe. access-related ischemia. (C) 2014 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved

Native dialysis shunts in children and adolescents. A single center analysis

Introduction. Even though early transplantation is still the first line therapy in pediatric and adolescent patients with end-stage renal disease (ESRD), up to 30% still require hemodialysis (HD) therapy. Creating an arteriovenous fistula (AVF) is challenging, particularly in small infants which is why catheters are frequently used in pediatric patients. This article describes experiences with the creation of AVFs which currently allows in-dwelling catheters to be completely avoided in children and adolescents on HD. Materials and methods. During the 59-month-period from January 2009 to December 2013 there were 34 patients rated as unsuitable for transplantation for at least the upcoming 6 months or who had already started HD therapy using a central venous catheter (CVC) some months previously. Of these patients 3 were aged between 12 and 36 months, weighed 9-12 kg and received HD treatment through a cuffed, tunnelled CVC via the jugular vein. The other 31 patients were 6-19 years of age and were assigned to receive the alternative AV fistula. Results. During the 59-month time period 31 patients were provided with 32 AVFs, 26 received a peripheral radiocephalic fistula, 5 a Gracz type fistula and 1 a brachiobasilic fistula. All but two fistulae matured primarily within an average time of 45 (range 16-191) days until the first cannulation. The 12-month primary patency and primary assisted patency rates of the fistulas were 78% and 94%, respectively. Conclusion. The creation of native vascular accesses is an effective and reliable procedure in pediatric and adolescent patients. It allows central venous catheters to be avoided and should be used for long term hemodialysis treatment as well as a bridging procedure until renal transplantation