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At least 919 records · Page 51
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Percutaneous Endovascular Salvage Techniques for Implanted Venous Access Device Dysfunction

PurposeImplanted venous access devices (IVADs) are often used in patients who require long-term intravenous drug administration. The most common causes of device dysfunction include occlusion by fibrin sheath and/or catheter adherence to the vessel wall. We present percutaneous endovascular salvage techniques to restore function in occluded catheters. The aim of this study was to evaluate the feasibility, safety, and efficacy of these techniques.Methods and MaterialsThrough a femoral or brachial venous access, a snare is used to remove fibrin sheath around the IVAD catheter tip. If device dysfunction is caused by catheter adherences to the vessel wall, a new “mechanical adhesiolysis” maneuver was performed. IVAD salvage procedures performed between 2005 and 2013 were analyzed. Data included clinical background, catheter tip position, success rate, recurrence, and rate of complication.ResultsEighty-eight salvage procedures were performed in 80 patients, mostly women (52.5 %), with a mean age of 54 years. Only a minority (17.5 %) of evaluated catheters were located at an optimal position (i.e., cavoatrial junction ±1 cm). Mechanical adhesiolysis or other additional maneuvers were used in 21 cases (24 %). Overall technical success rate was 93.2 %. Malposition and/or vessel wall adherences were the main cause of technical failure. No complications were noted.ConclusionThese IVAD salvage techniques are safe and efficient. When a catheter is adherent to the vessel wall, mechanical adhesiolysis maneuvers allow catheter mobilization and a greater success rate with no additional risk. In patients who still require long-term use of their IVAD, these procedures can be performed safely to avoid catheter replacement.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Improving Alpha Spectrometry Energy Resolution by Ion Implantation with ICP-MS

We report results of a novel technique using an Inductively Coupled Plasma Mass Spectrometer (ICP-MS) as a method of source preparation for alpha spectrometry. This method produced thin, contaminant free 241Am samples which yielded extraordinary energy resolution which appear to be at the lower limit of the detection technology used in this research.

Dion, Michael P.↗
DOE OSTI2019

Mg-3Zn/HA Biodegradable Composites Synthesized via Spark Plasma Sintering for Temporary Orthopedic Implants

In the present study, an attempt has been made to improve the mechanical properties, biocompatibility and degradation rate of Mg/3Zn matrix composite, by reinforcing with chemically inert and osteoconductive hydroxyapatite (HA). The composites were synthesized through spark plasma sintering for better consolidation. The HA content, in Mg/3Zn matrix, was optimized with an aim of improving mechanical behavior, corrosion resistance and biocompatibility simultaneously. It has been observed that reinforcement with 15 wt.% HA could slow down the corrosion rate by ~ 60% and improve the hardness and compression strength by ~ 42.8 and 18%, respectively. In vitro studies, up to 56 days, unveil the effect of HA reinforcement in corrosion resistance of magnesium-based matrix. Osteoblastic activity has shown better cell proliferation on the composite surfaces, which were reinforced with HA.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Characterisation of radiation damage in W and W-based alloys from 2MeV self-ion near-bulk implantations

The displacement damage induced in bulk W and W-5 wt.% Re and W-5 wt.% Ta alloys by 2 MeV W + irradiation to doses 3.3×10 17 - 2.5×10 19 W + /m 2 at temperatures ranging from 300 to750°C has been characterized by transmission electron microscopy. An automated sizing and counting approach based on Image J has been proposed and performed for all irradiation data. In all cases the damage comprised dislocation loops, mostly of interstitial type, with Burgers vectors b = ½<111> (> 60%) and b = <100>. The diameters of loops did not exceed 20 nm, with the majority being ≤ 6 nm. The loop number density varied between 10 22 and 10 23 loops/m 3 . With increasing irradiation temperature, the loop size distributions shifted towards larger sizes, and there was a substantial decrease in loop number densities. The damage microstructure was less sensitive to dose than to temperature. Under the same irradiation conditions, loop number densities in the alloys were higher than in pure W but loops were smaller. In grains with normals close to z = <001>, loop strings developed in W at temperatures ≥ 500°C and doses ≥ 1.2 dpa, but such strings were not observed in the W-Re or W-Ta alloys. However, in other grain orientations complex structures appeared in all materials and dense dislocation networks formed at higher doses.

36 MATERIALS SCIENCE↗