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Long Needles (long + needle)
Selected AbstractsRadiofrequency Transseptal Catheter Electrode FracturePACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 6 2010ASHOK J. SHAH M.D. Transseptal puncture is performed using a long needle advanced from the femoral approach. A radiofrequency catheter has been developed that delivers a short burst of radiofrequency energy and creates a micro puncture in the interatrial septum. We describe a case in which the distal radiofrequency electrode broke and became embedded in the interatrial septum. (PACE 2010; 33:e57,e58) [source] Effect of AlN doping on the growth morphology of SiCCRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2009N. B. Singh Abstract AlN doped SiC films were deposited on on-axis Si-face 4H-SiC (0001) substrates by the physical vapor transport (PVT) method. Thick film in the range of 20 ,m range was grown and morphology was characterized. Films were grown by physical vapor deposition (PVD) in a vertical geometry in the nitrogen atmosphere. We observed that nucleation occurred in the form of discs and growth occurred in hexagonal geometry. The X-ray studies showed (001) orientation and full width of half maxima (FWHM) was less than 0.1° indicating good crystallinity. We also observed that film deposited on the carbon crucible had long needles with anisotropic growth very similar to that of pure AlN. Some of the needles grew up to sizes of 200 ,m in length and 40 to 50 ,m in width. It is clear that annealing of SiC-AlN powder or high temperature physical vapor deposition produces similar crystal structure for producing AlN-SiC solid solution. SEM studies indicated that facetted hexagons grew on the top of each other and coarsened and merged to form cm size grains on the substrate. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Aligned Nanofibers: Epitaxial Growth of Highly Oriented Fibers of Semiconducting Polymers with a Shish-Kebab-Like Superstructure (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 17 2009Mater. Highly oriented fibers of regioregular poly(3-alkylthiophene)s with a "shish-kebab" morphology are prepared by epitaxy on long needles of 1,3,5-trichlorobenzene grown in liquid pyridine, as described on page 2759 by Brinkmann et al. The superstructure of the fibers consists of a highly oriented thread-like core several hundreds of micrometers long, the "shish", onto which lateral crystalline nanofibrils made of folded polymer chains, the "kebabs", are connected in a periodic way. [source] Epitaxial Growth of Highly Oriented Fibers of Semiconducting Polymers with a Shish-Kebab-Like SuperstructureADVANCED FUNCTIONAL MATERIALS, Issue 17 2009Martin Brinkmann Abstract Highly oriented fibers of regioregular poly(3-alkylthiophene)s (P3ATs) showing a "shish-kebab" morphology are prepared by oriented epitaxial crystallization in a mixture of 1,3,5-trichlorobenzene (TCB) and pyridine. The superstructure of the P3AT fibers consists of an oriented thread-like core several hundreds of micrometers long, the "shish", onto which lateral crystalline fibrils made of folded polymer chains, the "kebabs", are connected in a periodic way with a periodicity in the range 18,30,nm. The P3AT-chain axis is oriented parallel to the fiber axis whereas the ,-stacking direction is oriented perpendicular to it. The oriented character of the shish-kebab fibers results in polarized optical absorption and photoluminescence. The formation of oriented precursors by epitaxial orientation of polymer chains onto long needles of a molecular crystal,TCB in the present case,appears to be an original alternative to the crystallization usually performed under external flow conditions. [source] Sphere-to-Rod Transition of Micelles formed by the Semicrystalline Polybutadiene- block -Poly(ethylene oxide) Block Copolymer in a Selective SolventMACROMOLECULAR RAPID COMMUNICATIONS, Issue 5 2010Adriana M. Mihut Abstract We present a morphological study of the micellization of an asymmetric semicrystalline block copolymer, poly(butadiene)- block -poly(ethylene oxide), in the selective solvent n -heptane. The molecular weights of the poly(butadiene) (PB) and poly(ethylene oxide) (PEO) blocks are 26 and 3.5,kg,·,mol,1, respectively. In this solvent, micellization into a liquid PEO-core and a corona of PB-chains takes place at room temperature. Through a thermally controlled crystallization of the PEO core at ,30,°C, spherical micelles with a crystalline PEO core and a PB corona are obtained. However, crystallization at much lower temperatures (,196,°C; liquid nitrogen) leads to the transition from spherical to rod-like micelles. With time these rod-like micelles aggregate and form long needles. Concomitantly, the degree of crystallinity of the PEO-cores of the rod-like micelles increases. The transition from a spherical to a rod-like morphology can be explained by a decrease of solvent power of the solvent n -heptane for the PB-corona chains: n -Heptane becomes a poor solvent at very low temperatures leading to a shrinking of the coronar chains. This favors the transition from spheres to a morphology with a smaller mean curvature, that is, to a cylindrical morphology. [source] A Cosmetic Approach for Pectoral Pacemaker Implantation in Young GirlsPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 9 2000ERIC ROSENTHAL Pectoral placement of pacemaker generators, combined with use of a redundant intravascular lead portion, reduces the need for endocardial lead advancement during growth in children. While the use of small generators and submuscular pockets has contributed to cosmetic acceptability, the conventional subclavicular incision may occasionally form a keloid scar that is unacceptable in young girls. A modified implantation technique was used in five girls (age 2.6,13.3 years) during implantation of VDD (n = 2), VVIR (n = 2), and DDDR (n = 1) pacemakers. A 5-cm incision was made in the axilla along the line of the pec-toralis major and dissection was continued below the muscle to create a pocket for the generator. Subclavian vein puncture was performed from the axillary incision and beneath the pectoralis major muscle using standard or extra long needles with a needle guard. Peel away sheaths were used for lead positioning. The generator was placed in the submuscular pocket and the wound closed with absorbable sutures. At follow-up, pacemaker function was excellent and neither the scars nor pacemakers were visible from the front. In conclusion, the axillary incision with direct subclavian vein puncture from below the pectoralis major muscle offers the advantages of pectoral pacemaker implantation through a single cosmetic incision. [source] An audit of peribulbar blockade using 15 mm, 25 mm and 37.5 mm needles, and sub-Tenon's injection,ANAESTHESIA, Issue 8 2004A. A. Van Den Berg Summary The efficacy of peribulbar anaesthesia performed with short, medium and long needles, with sub-Tenon's injection as a control, was audited. Two hundred patients undergoing cataract surgery underwent peribulbar injection using 25G needles of the following lengths: 15 mm, 25 mm or 37.5 mm. Sub-Tenon's injections were performed with a curved 25-mm sub-Tenon anaesthesia cannula. The injection technique, ocular akinesia and analgesia scoring system, and supplementary injection protocols were standardised. After initial injections of local anaesthetic via the sub-Tenon's cannula or with 37.5 mm, 25 mm and 15 mm needles, supplementation was required in one (2%), 13 (26%), 22 (44%) and 32 (64%) of patients, respectively; the total number of supplementary injections required were 1, 16, 35 and 47, respectively. It is concluded that the efficacy of peribulbar anaesthesia depends upon the proximity of the deposition of local anaesthetic solution either to the globe or orbital apex. These data justify the classification of peribulbar anaesthesia into: circum-ocular (sub-Tenon's, episcleral), peri-ocular (anterior, superficial); peri-conal (posterior, deep) and apical (ultra-deep) for teaching purposes. [source] | |||||||||||||