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David Hasler, Dominik Obrist
The flow field past a prosthetic aortic valve comprises many details that indicate whether the prosthesis is functioning well or not. It is, however, not yet fully understood how an optimal flow scenario would look, i.e. which subtleties of the fluid dynamics in place are essential regarding the durability and compatibility of a prosthetic valve. In this study, we measured and analyzed the 3D flow field in the vicinity of a bio-prosthetic heart valve in function of the aortic root size. The measurements were conducted within aortic root phantoms of different size, mounted in a custom-built hydraulic setup, which mimicked physiological flow conditions in the aorta...
2018: PloS One
Julia J Mack, M Luisa Iruela-Arispe
PURPOSE OF REVIEW: The formation of a hierarchical vascular network is a complex process that requires precise temporal and spatial integration of several signaling pathways. Amongst those, Notch has emerged as a key regulator of multiple steps that expand from endothelial sprouting to arterial specification and remains relevant in the adult. This review aims to summarize major concepts and rising hypotheses on the role of Notch signaling in the endothelium. RECENT FINDINGS: A wealth of new information has helped to clarify how Notch signaling cooperates with other pathways to orchestrate vascular morphogenesis, branching, and function...
March 14, 2018: Current Opinion in Hematology
Diego Jaramillo-Cano, Maud Formanek, Christos N Likos, Manuel Camargo
Star block-copolymers (SBCs) have been demonstrated to constitute self-assembling building blocks with specific softness, functionalization, shape and flexibility. In this work we study the behaviour of an isolated SBC under shear flow by means of particle-based multi-scale simulations. We systematically analyse the conformational properties of low-functionality stars as well as the formation of attractive patches on their corona as a function of the shear rate. We cover a wide range of system parameters, including functionality, amphiphilicity and solvent quality...
March 16, 2018: Journal of Physical Chemistry. B
Ran Chen, Ying Lu, Zhiyong Jiang, Yongfeng Men
The poly(4-methyl-1-pentene) sample was used to investigate the cavitation induced stress-whitening phenomenon during stretching at different temperatures via the ultra-small-angle X-ray scattering technique. Two modes of cavitation were found that mode I cavitation activated around yield point followed by mode II cavitation generated in highly oriented state. The critical strain for initiating the mode II cavitation increases with the increase of stretching temperature whereas the critical stress grew steadily in the lower temperature regime (30~60oC) and reached a plateau at 70oC...
March 16, 2018: Journal of Physical Chemistry. B
Yashwant Singh Tanwar, Yatinder Kharbanda, Atin Jaiswal, Vikas Birla, Ramsagar Pandit
INTRODUCTION: Coronal plane distal humeral injuries are relatively rare. Numerous classification systems have been proposed as the complexity of these fractures has been realized. We in the present series of ten patients describe the surgical technique of Open Reduction and Internal Fixation of Coronal plane fractures of the distal humerus with headless compression screws performed using the anterolateral approach. MATERIAL AND METHOD: It was a retrospective study, the data collected from March 2010 to 2015 was analysed and the final outcome was assessed using the DASH score...
2018: SICOT-J
Pinar Cevik, Oguz Eraslan, Kursat Eser, Suleyman Tekeli
PURPOSE: The aim of this study was to evaluate the effect of six different surface conditioning methods on the shear bond strength of ceramic brackets bonded to feldspathic porcelain. MATERIALS AND METHODS: A total of 60 feldspathic porcelain disks were fabricated and divided into six subgroups including 10 specimens in each. Specimens were first treated one of the following surface conditioning methods, namely, 37% phosphoric acid (G-H3PO4), 9.4% hydrofluoric acid (G-HF), grinding with diamond burs (G-Grinding), Nd:YAG laser (G-Nd:YAG), Airborne-particle abrasion (G-Abrasion)...
March 2018: International Journal of Artificial Organs
Andrea J Santamaría, Juan P Solano, Francisco D Benavides, James D Guest
Cell transplant-mediated tissue repair of the damaged spinal cord is being tested in several clinical trials. The current candidates are neural stem cells, stromal cells, and autologous Schwann cells (aSC). Due to their peripheral origin and limited penetration of astrocytic regions, aSC are transplanted intralesionally as compared to neural stem cells that are transplanted into intact spinal cord. Injections into either location can cause iatrogenic injury, and thus technical precision is important in the therapeutic risk-benefit equation...
2018: Methods in Molecular Biology
Mohamed A Mohamed, Rohit Abraham, Tareq I Maraqa, Samir Elian
Aortic dissection is a rare and fatal complication of cocaine-induced hypertension. The injury mechanism is through shear stress that penetrates the intimal vessel layer, allowing blood flow to separate intimal and medial layers. Due to its scarcity and the paucity of related literature, our knowledge of this condition is limited. We present a rare case of a cocaine-induced aortic dissection, which extended continuously from the aortic root to the common iliacs, along with a literature review of similar cases...
January 12, 2018: Curēus
Jiangwei Wang, Yanming Wang, Wei Cai, Jixue Li, Ze Zhang, Scott X Mao
Shear band in metallic crystals is localized deformation with high dislocation density, which is often observed in nanopillar deformation experiments. The shear band dynamics coupled with dislocation activities, however, remains unclear. Here, we investigate the dynamic processes of dislocation and shear band in body-centered cubic (BCC) tungsten nanowires via an integrated approach of in situ nanomechanical testing and atomistic simulation. We find a strong effect of surface orientation on dislocation nucleation in tungsten nanowires, in which {111} surfaces act as favorite sites under high strain...
March 15, 2018: Scientific Reports
H C Sun, Z L Ning, G Wang, W Z Liang, S Pauly, Y J Huang, S Guo, X Xue, J F Sun
ZrCu-based bulk metallic glass composites (BMGCs) are well known for their plastic deformability, superior to traditional metallic glasses (MGs), which is attributed to a unique dual-phases structure, namely, the glassy matrix and unstable B2 phase. In the present study, in-situ tensile testing is used to trace the deformation process of a ZrCu-based BMGC. Three deformation stages of the BMGC, i.e., the elastic-elastic stage, the elastic-plastic stage, and the plastic-plastic stage are identified. In the elastic-elastic and elastic-plastic stages, the yield strength and elastic limit are major influenced by the volume fraction of the B2 crystals...
March 15, 2018: Scientific Reports
Burak Kurşun, Levent Uğur, Gökhan Keskin
BACKGROUND AND OBJECTIVE: Hemodynamic analyzes are used in the clinical investigation and treatment of cardiovascular diseases. In the present study, the effect of bypass geometry on intracranial aneurysm hemodynamics was investigated numerically. Pressure, wall shear stress (WSS) and velocity distribution causing the aneurysm to grow and rupture were investigated and the best conditions were tried to be determined in case of bypassing between basilar (BA) and left/right posterior arteries (LPCA/RPCA) for different values of parameters...
May 2018: Computer Methods and Programs in Biomedicine
Da Yong Shin, Min-Ho Kang, In-Gu Kang, Hyoun-Ee Kim, Seol-Ha Jeong
A biodegradable polylactic acid composite containing tricalcium phosphate microsphere was fabricated. The composite exhibited enhanced biocompatibility and a well-interconnected porous structure that enabled tissue ingrowth after degradation. The tricalcium phosphate microspheres had an average size of 106 ± 43 μm and were incorporated into the polylactic acid matrix using a high-shear mixer. The resulting bioactivity and hydrophilicity were enhanced to levels comparable to those of a polylactic acid composite containing tricalcium phosphate powder, which is a well-known material used in the medical field...
January 1, 2018: Journal of Biomaterials Applications
Cédric Garcia, Nicolas Montée, Julien Faccini, Jennifer Series, Olivier Meilhac, Anne-Valérie Cantero, Pauline Le Faouder, Meyer Elbaz, Bernard Payrastre, Cécile Vindis
BACKGROUND: While high-density lipoproteins (HDL) have anti-thrombotic effects by reducing platelet activation, the relationship between HDL levels and the risk of acute coronary syndrome (ACS) is unclear since HDL particles are heterogeneous in composition and biological properties OBJECTIVE: We characterized the effects of HDL2 and HDL3 subclasses from ACS patients and non-coronary artery disease (CAD) subjects on platelet activation. METHODS: We measured platelet aggregation and ex vivo thrombus formation, analyzed signaling pathways by flow cytometry and performed a targeted lipidomics analysis on HDL subclasses RESULTS: Analysis of human platelet aggregation in suspension, adhesion on von Willebrand factor and thrombus formation on collagen under arterial shear demonstrated that HDL2 subclass from ACS patients had a higher antiplatelet potency compared to ACS HDL3 particles and HDL subclasses from non-CAD subjects...
March 15, 2018: Journal of Thrombosis and Haemostasis: JTH
J Ruiz-Franco, J Marakis, N Gnan, J Kohlbrecher, M Gauthier, M P Lettinga, D Vlassopoulos, E Zaccarelli
Ultrasoft colloids typically do not spontaneously crystallize, but rather vitrify, at high concentrations. Combining in situ rheo-small-angle-neutron-scattering experiments and numerical simulations we show that shear facilitates crystallization of colloidal star polymers in the vicinity of their glass transition. With increasing shear rate well beyond rheological yielding, a transition is found from an initial bcc-dominated structure to an fcc-dominated one. This crystal-to-crystal transition is not accompanied by intermediate melting but occurs via a sudden reorganization of the crystal structure...
February 16, 2018: Physical Review Letters
Z H Zhong, R X Tang, M Zhou, X H Deng, Y Pang, W R Paterson, B L Giles, J L Burch, R B Tobert, R E Ergun, Y V Khotyaintsev, P-A Lindquist
Secondary flux ropes are suggested to play important roles in energy dissipation and particle acceleration during magnetic reconnection. However, their generation mechanism is not fully understood. In this Letter, we present the first direct evidence that a secondary flux rope was generated due to the evolution of an electron vortex, which was driven by the electron Kelvin-Helmholtz instability in an ion diffusion region as observed by the Magnetospheric Multiscale mission. The subion scale (less than the ion inertial length) flux rope was embedded within the electron vortex, which contained a secondary electron diffusion region at the trailing edge of the flux rope...
February 16, 2018: Physical Review Letters
Akiko Oota-Ishigaki, Toru Masuzawa, Kazuaki Nagayama
Thrombus formation on biomaterial surfaces with microstructures is complex and not fully understood. We have studied the micro-secondary flow around microstructures that causes components of blood to adhere physically in a low Reynolds number region. The purpose of this study was to investigate the effect of micro-column size on the adhesion phenomena and show a quantitative relationship between the micro-secondary flow and physical adhesion phenomena, considering microstructures of various sizes. The flow simulation and quantitative assessment of adhesion rates around micro-columns was conducted using four sizes of micro-columns...
March 1, 2018: International Journal of Artificial Organs
Bahar Bilgen, Chathuraka T Jayasuriya, Brett D Owens
The meniscus is the most commonly injured structure in the human knee. Meniscus deficiency has been shown to lead to advanced osteoarthritis (OA) due to abnormal mechanical forces, and replacement strategies for this structure have lagged behind other tissue engineering endeavors. The challenges include the complex 3D structure with individualized size parameters, the significant compressive, tensile and shear loads encountered, and the poor blood supply. In this progress report, a review of the current clinical treatments for different types of meniscal injury is provided...
March 15, 2018: Advanced Healthcare Materials
Zaiyang Long, Donald J Tradup, Pengfei Song, Scott F Stekel, Shigao Chen, Katrina N Glazebrook, Nicholas J Hangiandreou
Because of the rapidly growing use of ultrasound shear wave elastography (SWE) in clinical practices, there is a significant need for development of clinical physics performance assessment methods for this technology. This study aims to report two clinical medical physicists' tasks: (a) acceptance testing (AT) of SWE function on ten commercial ultrasound systems for clinical liver application and (b) comparison of SWE measurements of targets across vendors for clinical musculoskeletal application. For AT, ten GE LOGIQ E9 XDclear 2...
March 15, 2018: Journal of Applied Clinical Medical Physics
Mat Nicholls, Ajay Manjoo, Peter Shaw, Faizan Niazi, Jeffrey Rosen
INTRODUCTION: This study aims to compare the properties of currently available intra-articular hyaluronate (IA-HA) products widely available in the USA to those of healthy knee synovial fluid with respect to their bulk rheological properties. We hypothesize that products would have differing rheological properties, with some more closely resembling the properties and physiological aspects of healthy joint fluid HA. METHODS: We obtained reported HA product molecular weights, as well as measurements of the presence of cross-linking, zero shear rate viscosity, shear thinning ratio, and crossover frequency for the following IA-HA products available in the USA: Euflexxa® , Orthovisc® , Supartz® , Monovisc® , Synvisc® , Synvisc-One® , Gel-One® , and Hyalgan® ...
March 14, 2018: Advances in Therapy
Daniel J Ellenberger, Dave A Miller, Sandra U Kucera, Robert O Williams
Vemurafenib is a poorly soluble, low permeability drug that has a demonstrated need for a solubility-enhanced formulation. However, conventional approaches for amorphous solid dispersion production are challenging due to the physiochemical properties of the compound. A suitable and novel method for creating an amorphous solid dispersion, known as solvent-controlled coprecipitation, was developed to make a material known as microprecipitated bulk powder (MBP). However, this approach has limitations in its processing and formulation space...
March 14, 2018: AAPS PharmSciTech
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