Contributors:Meiyu Gai, Johannes Frueh, Tieyan Si, Narsiu Hu, Gleb B. Sukhorukov, Qiang He
The collision phenomena of self-propelled micro-plate motors are significantly different from classical life-less particles. The Janus micro-plate motors used in this study are 5 and 10μm in diameter and driven by catalytic decomposition of hydrogen peroxide. Periodically oscillating oxygen bubbles drive the motor in rugged straight or spiral motion. Since the inertia effect of mass is no longer important for slow motion in low Reynold number liquid, the momentum law of collision shows some new characteristics due to the constant self-propelling force. We found a bounce back collision and a linear collision between the bubbles of one motor and the micromotor plates as well as between 2 microplates and present a basic theoretical concept. In addition we show experimentally that these 2D particles are able to destroy emerging gas bubbles. More complex collision dynamics may exist for a higher concentration of self-propelled motors.
The application of transcatheter aortic valve implantation (TAVI) in a wider and younger population in the near future makes the need to successfully deal with challenging procedural conditions an imperative. We report a case in which TAVI was successfully conducted in a patient with aortic coarctation using a last-generation low-profile bioprosthesis. Despite the fragile aortic wall and its possible abnormal function, a low-profile (14F) CoreValve Evolute R device (Medtronic, Minneapolis, MN) was implanted through the coarctation without complications. Last-generation, low-profile transcatheter implanted aortic valves provide an additional advantage in patients with structural impediments.
Contributors:Gonzalo Luis Alonso Salinas, Sara Fernandez Santos, Ignacio Pinilla Pagnon, Javier Miguelena Hycka, Ines Pecharromán, Marcelo Sanmartín Fernández, Marina Pascual Izco, Jose Julio Jimenez-Nacher, Covadonga Fernandez-Golfin, Jose Luis Zamorano
We report on a 49 years man presented to the Emergency Department with progressive angina. Echocardiography displayed severe aortic regurgitation and aortic valve thickening. The suspected diagnosis was acute aortic syndrome. CCT showed circumferential thickening of the aortic wall and left main coronary artery ostial stenosis. Histological examination showed diffuse aortic inflammation. No damage of any other organ or vascular structure was reported and final diagnosis was non-specific aortitis. Differential diagnosis, prognosis and therapeutical strategies are discussed.
Contributors:Giuseppe Giacchi, Xavier Freixa, Marco Hernández-Enríquez, Laura Sanchis, Manel Azqueta, Salvatore Brugaletta, Victoria Martin-Yuste, Mónica Masotti, Manel Sabaté
Two patients with severe aortic paravalvular leaks (PVLs) in a mechanical prosthesis were percutaneously treated. Procedures were performed with mild sedation, angiographic guidance and 6 Fr. right radial artery approach with good final results.
We investigate the fracture properties of organic-rich shale at the microscopic scale by coupling advanced imaging techniques, fracture mechanics and micro-scale mechanical testing methods. We study three shale systems: Toarcian (Paris Basin, France), and Lower and Upper Woodford shale (Oklahoma, US). A material preparation procedure is designed so as to visualize the microstructure. Optical microscopy and scanning electron microscopy reveal a porous granular fabric with the grain size ranging from 30 to 100μm as well as micron-sized air voids. Microscopic scratch tests are carried out, during which a stylus is pushed across the surface of a material under a prescribed monotonically increasing vertical load. We develop a fracture mechanics approach that takes into account the heterogeneity and anisotropy of gas shale. The microscopic scratch toughness predicted by the scratch fracture model is 2.35–2.98MPam, which is two times higher than the macroscopic fracture toughness. A microscopic examination of the fracture surface reveals toughening mechanisms such as particle pull out, crack front roughening and crack bridging. The methodology presented is new and will pave the way toward a mechanistic physics-based understanding of the fracture behavior of gas shale at multiple length scales. In turn, this will accelerate the design of optimum and efficient schemes to extract natural gas from unconventional shale.
Infection of coronary stents is extremely rare. We report a case of a 60-year-old gentleman with recurrent fever after acute stent occlusion and reintervention. A coronary angiogram showed an occluded stented segment and the blood cultures were positive for infection. The presence of inflammation in the stented region was confirmed using 18F-flurodeoxyglucose positron emission tomography computed tomography. The patient underwent surgery and the diagnosis was proven by examination of the surgical material. This article highlights the need to have a high index of suspicion of stent infection, and the use of 18F-flurodeoxyglucose positron emission tomography computed tomography along with coronary angiogram in aiding the diagnosis.
Contributors:Mingteng Lu, Xianyu Su, Yiping Cao, Zhisheng You, Min Zhong
In order to determine Dynamic 3-D shape with vertical measurement mode, a fast modulation measuring profilometry (MMP) with a cross grating projection and single shot is proposed. Unlike the previous methods, in our current projection system, one cross grating is projected by a special projection lens consisting of a common projection lens and a cylindrical lens. Due to the characteristics of cylindrical lens, the image of the vertical component and the horizontal component of the cross grating is separated in the image space, and the measuring range is just the space between the two image planes. Through a beam splitter, the CCD camera can coaxially capture the fringe pattern of the cross grating modulated by the testing object׳s shape. In one fringe pattern, by applying Fourier transform, filtering and inverse Fourier transform, the modulation corresponding to the vertical and horizontal components of the cross grating can be obtained respectively. Then the 3-D shape of the object can be reconstructed according to the mapping relationship between modulation and height, which was established by calibration process in advance. So the 3-D shape information can be recorded at the same speed of the frame rate of the CCD camera. This paper gives the principle of the proposed method and the set-up for measuring experiment and system calibration. The 3-D shape of a still object and a dynamic process of liquid vortex were measured and reconstructed in the experiments, and the results proved the method’s feasibility. The advantage of the proposed method is that only one fringe pattern is needed to extract the modulation distribution and to reconstruct the 3-D shape of the object. Therefore, the proposed method can achieve high speed measurement and vertical measurement without shadow and occlusion. It can be used in the dynamic 3-D shape measurement and vibration analysis.
Contributors:Anton Tomšič, Meindert Palmen, Michel I.M. Versteegh, Frank van der Kley, Hans-Marc J. Siebelink, Remco R. Berendsen, Martin J. Schalij
Transapical valve-in-valve mitral valve implantation has been described as an alternative treatment option in patients with degenerated bioprosthesis in the mitral position. We report the first case of prosthesis dislocation and migration into the left atrium following transapical valve-in-valve implantation. A new prosthesis was implanted using the same approach. The dislocated prosthesis was successfully removed through the left atrial appendage through an extended anterolateral thoracotomy without the use of cardiopulmonary bypass.