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Jacques Pécréaux, Stefanie Redemann, Zahraa Alayan, Benjamin Mercat, Sylvain Pastezeur, Carlos Garzon-Coral, Anthony A Hyman, Jonathon Howard
Precise positioning of the mitotic spindle is important for specifying the plane of cell division, which in turn determines how the cytoplasmic contents of the mother cell are partitioned into the daughter cells, and how the daughters are positioned within the tissue. During metaphase in the early Caenorhabditis elegans embryo, the spindle is aligned and centered on the anterior-posterior axis by a microtubule-dependent machinery that exerts restoring forces when the spindle is displaced from the center. To investigate the accuracy and stability of centering, we tracked the position and orientation of the mitotic spindle during the first cell division with high temporal and spatial resolution...
October 18, 2016: Biophysical Journal
Dilraj S Grewal, Tamer H Mahmoud
A 54-year-old male developed symptomatic scleral buckle exposure 16 years after placement and presented with large conjunctival defects with fibrosed edges. Following surgical removal of the buckle elements, primary conjunctival closure could not be achieved due to significant wound tension despite undermining the conjunctival edges to mobilize the conjunctiva. A dehydrated amniotic membrane graft (Ambio5; IOP Ophthalmics, Costa Mesa, CA) was placed on the scleral bed and secured in place with fibrin sealant (TISSEEL; Baxter International, Westlake Village, CA)...
October 1, 2016: Ophthalmic Surgery, Lasers & Imaging Retina
Rolf E Isele-Holder, Julia Jäger, Guglielmo Saggiorato, Jens Elgeti, Gerhard Gompper
Worm-like filaments, which are propelled by a tangential homogeneous force along their contour, are studied as they push loads of different shapes and sizes. The resulting dynamics is investigated using Langevin dynamics simulations. The effects of size and shape of the load, propulsion strength, and thermal noise are systematically explored. The propulsive force and hydrodynamic friction of the load cause a compression in the filament that results in a buckling instability and versatile motion. Distinct regimes of elongated filaments, curved filaments, beating filaments, and filaments with alternating beating and circular motion are identified, and a phase diagram depending on the propulsion strength and the size of the load is constructed...
October 19, 2016: Soft Matter
Joseph Cadman, Chester Sutterlin, Danè Dabirrahmani, Richard Appleyard
BACKGROUND: Commercial fusion cages typically provide support in the central region of the endplate, failing to utilize the increased compressive strength around the periphery. This study demonstrates the increase in compressive strength that can be achieved if the bony periphery of the endplate is loaded. METHODS: Sixteen cadaveric lumbar vertebrae (L1-L5) were randomly divided into two even groups. A different commercial mass produced implant (MPI) was allocated to each group: (I) a Polyether-ether-ketone (PEEK) anterior lumber inter-body fusion (ALIF) MPI; and (II) a titanium ALIF MPI...
September 2016: J Spine Surg
Suman Chowdhury, Debnarayan Jana
Inspired by the success of graphene, various two dimensional (2D) structures in free standing (FS) (hypothetical) form and on different substrates have been proposed recently. Silicene, a silicon counterpart of graphene, is predicted to possess massless Dirac fermions and to exhibit an experimentally accessible quantum spin Hall effect. Since the effective spin-orbit interaction is quite significant compared to graphene, buckling in silicene opens a gap of 1.55 meV at the Dirac point. This band gap can be further tailored by applying in plane stress, an external electric field, chemical functionalization and defects...
October 18, 2016: Reports on Progress in Physics
Leo Fradet, Xiaoyu Wang, Lawrence G Lenke, Carl-Eric Aubin
BACKGROUND: Proximal junctional failure is a severe proximal junctional complication following adult spinal instrumentation and involving acute proximal junctional kyphotic deformity, mechanical failure at the upper instrumented vertebra or just above, and/or proximal junctional osseoligamentous disruption. Clinical studies have identified potential risk factors, but knowledge on their biomechanics is still lacking for addressing the proximal junctional failure issues. The objective of this study was to develop comprehensive computational modeling and simulation techniques to investigate proximal junctional failure...
October 11, 2016: Clinical Biomechanics
Micol Alkabes, Domenico Massaro, Stefano Ranno, Paolo Nucci
PURPOSE: To describe the case of a young boy affected by a rhegmatogenous retinal redetachment in whom the use of peripheral optical coherence tomography led the vitreoretinal surgeon to treat the patient with an additional surgery instead of a "watchful waiting" strategy. METHODS: A 13-year-old boy was referred to the Vitreoretinal Department of the study institution affected by a macula-off rhegmatogenous retinal redetachment in his right eye secondary to a second blunt trauma...
October 3, 2016: Retinal Cases & Brief Reports
Xuejuan Liu, Falin Tian, Tongtao Yue, Xianren Zhang, Chongli Zhong
The shape deformation of membrane nanotubes is studied by a combination of theoretical analysis and molecular simulation. First we perform free energy analysis to demonstrate the effects of various factors on two ideal states for the pearling transition, and then we carry out dissipative particle dynamics simulations, through which various types of membrane tube deformation are found, including membrane pearling, buckling, and bulging. Different models for inducing tube deformation, including the osmotic pressure, area difference and spontaneous curvature models, are considered to investigate tubular instabilities...
October 17, 2016: Soft Matter
Keith A Seffen
We are inspired by the tensile buckling of a thin sheet with a slit to create a foldable planar metamaterial. The buckled shape comprises two pairs of identical e-cones connected to the slit, which we refer to as a k-cone. We approximate this shape as discrete vertices that can be folded out of plane as the slit is pulled apart. We determine their kinematics and we calculate generic shape properties using a simple elastic model of the folded shape. We then show how the folded sheet may be tessellated as a unit cell within a larger sheet, which may be constructed a priori by cutting and folding the latter in a regular way, in order to form a planar kirigami structure with a single degree of freedom...
September 2016: Physical Review. E
Xuezhi Ma, Yangzhi Zhu, Sanggon Kim, Qiushi Liu, Peter Byrley, Yang Wei, Jin Zhang, Kaili Jiang, Shoushan Fan, Ruoxue Yan, Ming Liu
Despite many efforts to fabricate high-aspect-ratio atomic force microscopy (HAR-AFM) probes for high-fidelity, high-resolution topographical imaging of three-dimensional (3D) nano-structured surfaces, current HAR probes still suffer from unsatisfactory performance, low wear-resistivity, and extravagant prices. The primary objective of this work is to demonstrate a novel design of a high-resolution (HR) HAR AFM probe, which is fabricated through a reliable, cost-efficient bench-top process to precisely implant a single ultra-sharp metallic nanowire on a standard AFM cantilever probe...
October 14, 2016: Nano Letters
Erich Hellemann, Rubens R Teles, Fernando Hallwass, W Barros, Armando Navarro-Vázquez, Roberto R Gil
Anisotropic NMR parameters, such as residual dipolar couplings (RDCs), residual chemical shift anisotropies (RCSAs) and residual quadrupolar couplings (RQCs or ΔνQ ), appear in solution-state NMR when the molecules under study are subjected to a degree of order. The tunable alignment by reversible compression/relaxation of gels (PMMA and p-HEMA) is an easy, user-friendly, and very affordable method to measure them. When using this method, a fraction of isotropic NMR signals is observed in the NMR spectra, even at a maximum degree of compression...
October 14, 2016: Chemistry: a European Journal
Yusuke Ito, Ikuo Yamazaki, Yoichi Kikuchi, Eri O'uchi, Toshihiro O'uchi, Hiroaki Kato, Kazuki Hotta
Recognizing imaging characteristics after ophthalmic surgery is necessary for radiologists to prevent misdiagnosis. We review typical appearances of intraorbital implanted devices and materials on CT and MRI with demonstration of the common surgical procedures. EX-PRESS glaucoma filtration devices appear as punctate areas of metal attenuation on CT and are typically placed at the corneoscleral junction. The imaging manifestations after cataract extraction are absence of the native lens of ovoid mass and the intraocular lens with high attenuation on CT and low signal intensity on MRI...
October 13, 2016: Japanese Journal of Radiology
Orlin Belyaev, Oleg Tcholakov, Waldemar Uhl
A 5-year-old boy sustained blunt abdominal trauma in a car crash. The buckle mechanism of the five-point harness of his child safety seat compressed his upper abdomen causing an isolated complete pancreatic rupture. Diagnosis was delayed due to subtle symptoms and normal initial findings. A CT scan confirmed diagnosis. An emergency limited central pancreatic resection was performed. The outcome was excellent.
October 13, 2016: Acta Chirurgica Belgica
Maria B Mesch, Kilian Bärwinkel, Yaşar Krysiak, Charlotte Martineau, Francis Taulelle, Reinhard B Neder, Ute Kolb, Jürgen Senker
Poly(triazine imide) with incorporated lithium chloride has recently attracted substantial attention due to its photocatalytic activity for water splitting. However, an apparent H/Li disorder prevents the delineation of structure-property relationships, for example, with respect to band-gap tuning. Herein, we show that through a combination of one- and two-dimensional, multinuclear solid-state NMR spectroscopy, chemical modelling, automated electron diffraction tomography, and an analysis based on X-ray pair distribution functions, it is finally possible to resolve the H/Li substructure...
October 13, 2016: Chemistry: a European Journal
Jakob Buchheim, Hyung Gyu Park
Polymer melt infiltration is one of the feasible methods for manufacturing filter membranes out of carbon nanotubes (CNTs) on large scales. Practically, however, its process suffers from low yields, and the mechanism behind this failure is rather poorly understood. Here, we investigate a failure mechanism of polymer melt infiltration of vertical aligned (VA-) CNTs. In penetrating the VA-CNT interstices, polymer melts exert a capillarity-induced attractive force laterally on CNTs at the moving meniscus, leading to locally agglomerated macroscale bunches...
October 13, 2016: Nanotechnology
Yong-Jiang Zhang, Fulton E Rockwell, Adam C Graham, Teressa Alexander, N Michele Holbrook
We report a novel form of xylem dysfunction in angiosperms: reversible collapse of the xylem conduits of the smallest vein orders that demarcate and intrusively irrigate the areoles of Quercus rubra leaves. Cryo-scanning electron microscopy revealed gradual increases in collapse from ~ -2 MPa down to ~ -3 MPa, saturating thereafter (to -4 MPa). Over this range cavitation remained negligible in these veins. Imaging of rehydration experiments showed spatially variable recovery from collapse within 20 seconds, and complete recovery after two minutes...
October 12, 2016: Plant Physiology
Shaoting Lin, Tal Cohen, Teng Zhang, Hyunwoo Yuk, Rohan Abeyaratne, Xuanhe Zhao
Soft elastic layers with top and bottom surfaces adhered to rigid bodies are abundant in biological organisms and engineering applications. As the rigid bodies are pulled apart, the stressed layer can exhibit various modes of mechanical instabilities. In cases where the layer's thickness is much smaller than its length and width, the dominant modes that have been studied are the cavitation, interfacial and fingering instabilities. Here we report a new mode of instability which emerges if the thickness of the constrained elastic layer is comparable to or smaller than its width...
October 12, 2016: Soft Matter
Kasey Buckles, Andreas Hagemann, Ofer Malamud, Melinda Morrill, Abigail Wozniak
We exploit exogenous variation in years of completed college induced by draft-avoidance behavior during the Vietnam War to examine the impact of college on adult mortality. Our estimates imply that increasing college attainment from the level of the state at the 25th percentile of the education distribution to that of the state at the 75th percentile would decrease cumulative mortality for cohorts in our sample by 8 to 10 percent relative to the mean. Most of the reduction in mortality is from deaths due to cancer and heart disease...
September 3, 2016: Journal of Health Economics
Carl P Frick, Daniel R Merkel, Christopher M Laursen, Stephan A Brinckmann, Christopher M Yakacki
This study explores the functionalization of main-chain nematic elastomers with a conductive metallic surface layer using a polydopamine binder. Using a two-stage thiol-acrylate reaction, a programmed monodomain is achieved for thermoreversible actuation. A copper layer (≈155 nm) is deposited onto polymer samples using electroless deposition while the samples are in their elongated nematic state. Samples undergo 42% contraction when heated above the isotropic transition temperature. During the thermal cycle, buckling of the copper layer is seen in the direction perpendicular to contraction; however, transverse cracking occurs due to the large Poisson effect experienced during actuation...
September 26, 2016: Macromolecular Rapid Communications
Menelaos G Kanakis, Helen Michelakakis, Petros Petrou, Chrysanthi Koutsandrea, Ilias Georgalas
BACKGROUND: Maple syrup urine disease (MSUD) is a rare metabolic disorder, affecting the metabolism of branched chain amino-acids (Valine, Leukine, Isoleukine). We present a rare case of rhegmatogenous retinal detachment (RRD) in a MSUD patient. CASE PRESENTATION: We performed amino acid analysis of aqueous humour, vitreous and serum samples obtained during surgery from a 24 year old female MSUD patient successfully operated on RRD. Serum values for a-amino-butyric acid, valine, isoleucine, leucine, tyrosine, phenylalanine, ornithine and histidine were low, while values for citrulline, methionine and lysine were borderline low, all attributed to the patient's special diet...
October 3, 2016: BMC Ophthalmology
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