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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,387 records · Page 77
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Cryoablation of Hepatocellular Carcinoma with High-Risk for Percutaneous Ablation: Safety and Efficacy

PurposeThe aim of this study was to evaluate the safety and effectiveness of cryoablation in the treatment of subcapsular hepatocellular carcinoma (HCC) adjacent to various organs.Materials and MethodsTwenty-eight patients with subcapsular HCC were treated with cryoablation in our institution. The degree of peri-procedural pain was measured using the visual analog scale (VAS). Technical success, local tumor progression, and overall disease progression rates were calculated. Procedure-related complications were identified by reviewing electronic medical records. Biochemical data, including serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), and total bilirubin levels before and after the procedure were collected.ResultsSubcapsular HCC tumors were located near the gallbladder, colon, stomach, kidney, diaphragm, or abdominal wall. The technical success rate of cryoablation was 96.4 % (27/28). Local recurrence- and progression-free survival rates were 96 and 84 % at 6 months, and 82 and 43 % at 1 year, respectively. All patients survived during the follow-up period. The VAS pain score ranged from 0 to 3 (mean, 1.57). A major complication occurred in one patient (3.6 %) and minor complications occurred at a rate of 17.9 %. Transient elevations of serum AST, ALT, and bilirubin levels were observed.ConclusionCryoablation is a safe and an effective procedure for the treatment of subcapsular HCC adjacent to various major organs.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Resolution of Postural Orthostatic Tachycardia Syndrome After CT-Guided, Percutaneous T2 Ethanol Ablation for Hyperhidrosis

Postural orthostatic tachycardia syndrome is characterized by orthostatic intolerance. Orthostasis (or other mild physical stress) triggers a cascade of inappropriate tachycardia, lightheadedness, palpitations, and often fainting. The underlying defect is sympathetic dysregulation of the heart, which receives its sympathetic tone from the cervical and upper thoracic sympathetic ganglia. Primary hyperhidrosis is also thought to be the result of sympathetic dysregulation. We present the case of a patient treated with CT-guided, percutaneous T2 EtOH sympatholysis for craniofacial hyperhidrosis. The patient also suffered from postural orthostatic tachycardia syndrome for many years and was unresponsive to treatment. Immediately after sympatholysis, the patient experienced resolution of both craniofacial hyperhidrosis and postural orthostatic tachycardia syndrome.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Differences in Patient Characteristics and Midterm Outcome Between Asian and European Patients Treated with Radiofrequency Ablation for Hepatocellular Carcinoma

PurposeThe aim of this study was to compare patient characteristics and midterm outcomes after RFA for unresectable Hepatocellular carcinoma (HCC) in Asian and European cohorts.Materials and MethodsThe study was based on retrospective analysis of 279 patients (mean 64.8 ± 12.1 years; 208 males) treated with RFA for de novo HCC in tertiary referral centers in Singapore and the Netherlands, with median follow-up of 28.2 months (quartiles: 13.1–40.5 months). Cumulative incidence of recurrence and death were analyzed using a competing risk model.ResultsAge was higher in the Asian group: 66.5 versus 60.1 years (p < 0.0001). The most common etiology was hepatitis B in the Asian group (48.0 %) and alcohol-induced cirrhosis in Europeans (54.4 %); p < 0.001. Asian patients had less advanced disease: 35.5, 55.0, and 3.0 %, respectively, had BCLC 0, A, and B versus 21.5, 58.2, and 15.2 % in the European group (p = 0.01). The cumulative incidences of recurrence in the Asian group at 1, 2, 3, and 5 years were 37.0, 56.4, 62.3, and 67.7 %, respectively, compared to 32.6, 47.2, 49.7, and 53.4 % in the European group (p = 0.474). At 1, 2, 3, and 5 years, the cumulative incidence rates of death in the Asian group were 2.0, 3.9, 4.9, and 4.9 %, respectively, corresponding to 7.7, 9.2, 14.1, and 21.0 % in the European group (p = 0.155).ConclusionSimilar short-term treatment outcomes are achieved with RFA in HCC patients in the South-East Asian and Northern-European populations. Midterm recurrence and death rates differ between the groups as a result of differences in baseline patient characteristics and patient selection. Our study provides insight relevant to the design of future international studies.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Bayesian Integration and Characterization of Composition C-4 Plastic Explosives Based on Time-of-Flight Secondary Ion Mass Spectrometry and Laser Ablation-Inductively Coupled Plasma Mass Spectrometry

Key elements regarding the use of non-radioactive ionization sources will be presented as related to explosives detection by mass spectrometry and ion mobility spectrometry. Various non-radioactive ionization sources will be discussed along with associated ionization mechanisms pertaining to specific sample types.

Bayesian integration↗
DOE OSTI2014

Emission features and expansion dynamics of nanosecond laser ablation plumes at different ambient pressures

The influence of ambient pressure on the spectral emission features and expansion dynamics of a plasma plume generated on a metal target has been investigated. The plasma plumes were generated by irradiating Cu targets using 6 ns, 1064 nm pulses from a Q-switched Nd:YAG laser. The emission and expansion dynamics of the plasma plumes were studied by varying air ambient pressure levels ranging from vacuum to atmospheric pressure. The ambient pressure levels were found to affect both the line intensities and broadening along with the signal to background and signal to noise ratios and the optimum pressure conditions for analytical applications were evaluated. The characteristic plume parameters were estimated using emission spectroscopy means and noticed that the excitation temperature peaked ∼300 Torr, while the electron density showed a maximum ∼100 Torr. Fast-gated images showed a complex interaction between the plume and background air leading to changes in the plume geometry with pressure as well as time. Surface morphology of irradiated surface showed that the pressure of the ambient gas affects the laser-target coupling significantly.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2014

Short-interval multi-laser Thomson scattering measurements of hydrogen pellet ablation in LHD

Thomson scattering forms an important aspect of measuring the electron density and temperature profiles of plasmas. In this study, we demonstrate Thomson scattering measurements obtained over a short interval (<1 ms) by using an event triggering system with a multi-laser configuration. We attempt to use our system to obtain the electron temperature and density profiles before and immediately after pellet injection into the large helical device. The obtained profiles exhibit dramatic changes after pellet injection as per our shot-by-shot measurements. We believe that this measurement technique will contribute towards a better understanding of the physics of the pellet deposition.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Time-resolved spatial distribution of plasma in the ablation of a Ba₀.₆Sr₀.₄TiO₃ target by 25 ns KrF ultraviolet laser

We performed radially and longitudinally time-resolved plasma analysis during pulsed laser deposition of Ba₀.₆Sr₀.₄TiO₃ thin films. The plasma is shown to be optically thick and strongly non-uniform during the early expansion phase and the resonance line Ba II (455.4 nm) is strongly self-reversed during this time. Plasma temperature and electron density were obtained by comparing experimental emission spectra with the spectral radiance computed for a non-uniform plasma in local thermal equilibrium.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Explosive boiling of a metallic glass superheated by nanosecond pulse laser ablation

We report an explosive boiling in a Zr-based (Vitreloy 1) bulk metallic glass irradiated by a nanosecond pulse laser with a single shot. This critical phenomenon is accompanied by the ejection of high-temperature matter from the target and the formation of a liquid-gas spinodal pattern on the irradiated area. An analytical model reveals that the glassy target experiences the normal heating (melting) and significant superheating, eventually culminating in explosive boiling near the spinodal limit. Furthermore, the time lag of nucleation and the critical radius of vapor bubbles are theoretically predicted, which are in agreement with the experimental observations. This study provides the investigation on the instability of a metallic glass liquid near the thermodynamic critical temperature.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗