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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Portal Vein Embolization before Right Hepatectomy: Improved Results Using n-Butyl-Cyanoacrylate Compared to Microparticles Plus Coils

Background: There is currently no consensus in the literature on which embolic agent induces the greatest degree of liver hypertrophy after portal vein embolization (PVE). Only experimental results in a pig model have demonstrated an advantage of n-butyl-cyanoacrylate (NBCA) over 3 other embolic materials (hydrophilic gel, small and large polyvinyl alcohol particles) for PVE. Therefore, the aim of this human study was to retrospectively compare the results of PVE using NBCA with those using spherical microparticles plus coils. Methods: A total of 34 patients underwent PVE using either NBCA (n = 20), or spherical microparticles plus coils (n = 14). PVE was decided according to preoperative volumetry on the basis of contrast-enhanced CT. Groups were compared for age, sex, volume of the left lobe before PVE and future remnant liver ratio (FRL) (volume of the left lobe/total liver volume - tumor volume). The primary end point was the increase in left lobe volume 1 month after PVE. Secondary end points were procedure complications and biological tolerance. Results: Both groups were similar in terms of age, sex ratio, left lobe volume, and FRL before PVE. NBCA induced a greater increase in volume after PVE than did microparticles plus coils (respectively, +74 {+-} 69 % and +23 {+-} 14 %, p < 0.05). The amount of contrast medium used for the procedure was significantly larger when microparticles and coils rather than NBCA were used (respectively, 264 {+-} 43 ml and 162 {+-} 34 ml, p < 0.01). The rate of PVE complications as well as the biological tolerance was similar in both groups. Conclusion: NBCA seems more effective than spherical microparticles plus coils to induce left-lobe hypertrophy.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Endovascular Embolization of Bronchial Artery Originating from the Upper Portion of Aortic Arch in Patients with Massive Hemoptysis

Purpose: Our experience with endovascular embolization (EVE) of the bronchial artery (BA) originating from the upper portion of the aortic arch (AA) in six patients is described. Methods: Altogether, 818 patients with hemoptysis underwent multidetector row computed tomography angiography (MDCTA) before EVE or AA angiography during EVE. Aberrant BAs originating from the upper portion of the AA were the source of massive hemoptysis in six patients (0.73 %). MDCT angiograms and/or Digital subtraction angiograms were retrospectively reviewed. Selective catheterization and embolization were performed. Results: The ostia of the BAs were located on the superior surface of the AA between the brachiocephalic trunk and left common carotid artery in three patients, the junction of the aorta and medial surface of the left subclavian artery in two, and the posterior wall of the upper portion of the AA in one. The six BAs comprised two common trunks, three single right sides, and one single left side. The targeted vessels were successfully catheterized and embolized by a coaxial microcatheter system using polyvinyl alcohol particles. Other pathologic BAs and nonbronchial systemic arteries also were embolized. Bleeding was immediately controlled in all patients with no recurrence of hemoptysis. No procedure-related complications occurred. Conclusions: Application of EVE of anomalous origin of BAs in patients with hemoptysis is important, as demonstrated in the six reported patients. MDCTA before EVE or AA angiography during EVE is critical to avoid missing a rare aberrant BA originating from the upper portion of the AA.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Safety and Effectiveness of UFE in Fibroids Larger than 10 cm

IntroductionEarly literature suggested that the size of the uterus, the size of the dominant fibroid, and the amount of applied embolization particles would be the risk factors for major postprocedural complications, but recent publications have confuted these early results. The purpose of our study was to evaluate whether the size of the dominant fibroid would influence the complication rate and effectiveness in a large single-center cohort.Patients and MethodsFrom 28 April 2008 until 31 December 2012, 303 patients had uterine artery embolization (UAE). 262 patients had small [largest diameter <10 cm (Group 1)], 41 patients had large [largest diameter >10 cm (Group 2)] fibroid. UAE was performed from unilateral femoral access using 500–710 and 355–500 µm polyvinyl alcohol particles. Periprocedural and postprocedural complications and numerical analog quality-of-life scores (0—unbearable symptoms; 100—perfect quality of life) were listed and statistically analyzed.ResultsDuring the mean follow-up time [7.79 ± 5.16 (SD) month], data on 275 patients (275/303 = 90.8 %) were available. Quality-of-life score was 33.3 ± 23.5 and 33.5 ± 24.1 before, whereas 85.6 ± 16.0 and 81.5 ± 23.5 after UAE in Group 1 and Group 2, respectively, (Mann–Whitney U test one-sided, p = 0.365). There were 4 myoma expulsions, 1 acute myomectomy, and 2 acute hysterectomies reported from Group 1, meanwhile 1 myoma expulsion, 1 acute myomectomy, and 2 acute hysterectomies were documented from Group 2 (NS differences).ConclusionThere was no significant difference in the effectiveness and in the number of minor and major complications between fibroids with <10 cm largest diameter compared to those >10 cm.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

An Attempt to Shorten Loading Time of Epirubicin into DC Beads{sup ®} Using Vibration and a Sieve

PurposeWe investigated the possibility of shortening the time required for loading epirubicin into calibrated polyvinyl alcohol-based hydrogel beads (DC Beads{sup ®}) to be used for transarterial chemoembolization.MethodAfter separating the beads suspended in phosphate-buffered saline (PBS) solution by the use of a sieve (clearance 75 µm), epirubicin hydrochloride (EH) was loaded for 20, 30, or 60 s under vibration into DC beads. The EH loading rate into conventionally prepared (control) beads, i.e., beads loaded for 30 min without vibration, and vibration-loaded beads were calculated from the residual EH concentration in the bead-depleted EH solution. The amount of EH eluted from conventionally and vibration-loaded samples into a PBS solution (pH 7.0) was measured at 15 and 30 min and 1, 2, 6, 12, and 24 h. We also recorded the inhibitory effect of the PBS solution on the loading time. Using frozen sections, the EH load in the beads was evaluated visually under a fluorescence microscope.ResultsSpectrophotometry (495 nm) showed that the loading rate was 98.98 ± 0.34, 99.02 ± 0.32, and 99.50 ± 0.11 % with 20-, 30-, and 60-s vibration, respectively. The eluted rate was statistically similar between vibration- and statically loaded (control) beads. The PBS solution hampered EH loading into the beads. Visually, the distribution of EH in conventionally and vibration-loaded DC beads was similar.DiscussionThe use of vibration and the removal of PBS solution when epirubicin hydrochloride was loaded into DC beads dramatically shortened the loading time of epirubicin hydrochloride into DC beads.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

First Human Experience with Directly Image-able Iodinated Embolization Microbeads

PurposeTo describe first clinical experience with a directly image-able, inherently radio-opaque microspherical embolic agent for transarterial embolization of liver tumors.MethodologyLC Bead LUMI™ is a new product based upon sulfonate-modified polyvinyl alcohol hydrogel microbeads with covalently bound iodine (~260 mg I/ml). 70–150 μ LC Bead LUMI™ iodinated microbeads were injected selectively via a 2.8 Fr microcatheter to near complete flow stasis into hepatic arteries in three patients with hepatocellular carcinoma, carcinoid, or neuroendocrine tumor. A custom imaging platform tuned for LC LUMI™ microbead conspicuity using a cone beam CT (CBCT)/angiographic C-arm system (Allura Clarity FD20, Philips) was used along with CBCT embolization treatment planning software (EmboGuide, Philips).ResultsLC Bead LUMI™ image-able microbeads were easily delivered and monitored during the procedure using fluoroscopy, single-shot radiography (SSD), digital subtraction angiography (DSA), dual-phase enhanced and unenhanced CBCT, and unenhanced conventional CT obtained 48 h after the procedure. Intra-procedural imaging demonstrated tumor at risk for potential under-treatment, defined as paucity of image-able microbeads within a portion of the tumor which was confirmed at 48 h CT imaging. Fusion of pre- and post-embolization CBCT identified vessels without beads that corresponded to enhancing tumor tissue in the same location on follow-up imaging (48 h post).ConclusionLC Bead LUMI™ image-able microbeads provide real-time feedback and geographic localization of treatment in real time during treatment. The distribution and density of image-able beads within a tumor need further evaluation as an additional endpoint for embolization.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Treatment Outcome Following Transarterial Chemoembolization in Advanced Bone and Soft Tissue Sarcomas

PurposeTransarterial chemoembolization (TACE) is used to treat unresectable bone and soft tissue sarcoma (STS) and as a pre-surgical adjuvant treatment. However, its efficiency for advanced STS is undetermined. This study evaluated TACE’s efficiency in treating advanced STS and prognostic factors for patient survival.Materials and MethodsWe enrolled 39 patients with unresectable STS who underwent TACE as an alternative treatment during 2010–2014, with overall survival (OS) as the primary end point. Cancer pain was evaluated by visual analogue scores (VAS) before and after TACE procedures. Factors that affect survival were evaluated by multivariate analyses (Cox proportional hazard model).ResultsMean OS after TACE was 23.7 ± 2.1 months, with 1-year OS 71.5 %, 2-year OS 45.8 %, and 3-year OS 32.5 %. Lesion number and tumor stage were key predictors of survival. TACE was found to decrease cancer pain VAS and increase relapse interval. Size of polyvinyl alcohol (PVA) particle diameter (P = 0.03) and imaging response (P = 0.044) were also found to affect relapse interval.ConclusionTACE was an effective treatment for advanced STS, with a 32.5 % 3-year OS rate, and led to lower cancer pain VAS and longer relapse intervals than chemoinfusion only. Smaller PVA particles are preferable during the TACE procedure.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Embolic Brain Infarcts: A Rare Fatal Complication of Preoperative Embolization of a Massive Solitary Fibrous Tumor of the Pleura

Solitary fibrous tumor of the pleura (SFTP) is a rare intrathoracic neoplasm, often giant in size and highly vascular, which can make surgical resection very challenging. Preoperative percutaneous embolization before surgical removal can significantly reduce the risk of uncontrollable intraoperative hemorrhage. However, a rare potential life threatening complication could result from embolization of SFTP and must be taken into consideration. This report describes a 69-year-old female with a large right thoracic SFTP, who underwent preoperative angiography and embolization and developed diffuse embolic brain infarcts immediately after the administration of polyvinyl alcohol particles.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

Magnetic Particle Imaging Guided Real-Time Percutaneous Transluminal Angioplasty in a Phantom Model

PurposeTo investigate the potential of real-time magnetic particle imaging (MPI) to guide percutaneous transluminal angioplasty (PTA) of vascular stenoses in a phantom model.Materials and MethodsExperiments were conducted on a custom-built MPI scanner. Vascular stenosis phantoms consisted of polyvinyl chloride tubes (inner diameter 8 mm) prepared with a centrally aligned cable tie to form ~ 50% stenoses. MPI angiography for visualization of stenoses was performed using the superparamagnetic iron oxide nanoparticle-based contrast agent Ferucarbotran (10 mmol (Fe)/l). Balloon catheters and guidewires for PTA were visualized using custom-made lacquer markers based on Ferucarbotran. Stenosis dilation (n = 3) was performed by manually inflating the PTA balloon with diluted Ferucarbotran. An online reconstruction framework was implemented for real-time imaging with very short latency time.ResultsVisualization of stenosis phantoms and guidance of interventional instruments in real-time (4 frames/s, ~ 100 ms latency time) was possible using an online reconstruction algorithm. Labeling of guidewires and balloon catheters allowed for precise visualization of instrument positions.ConclusionReal-time MPI-guided PTA in a phantom model is feasible.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Radiation-Chemical Synthesis of Crosslinked Films Based on N-Vinylcaprolactam Copolymers

Water-soluble copolymers were obtained by graft copolymerization of N-vinylcaprolactam and 2-hydroxyethyl acrylate on polyvinyl alcohol. The chemical composition of the obtained graft copolymers was determined by IR spectroscopy. Cross-linked films were obtained by radiation treatment of water-soluble copolymers. To estimate the efficiency of the radiation crosslinking of films, the dependence of the yield of gel fraction on the absorbed dose was studied at different proportions of the initial components. It was established that the yield of the crosslinked fraction increases and the swelling capacity of polymer mesh decreases with increasing 2-hydroxyethyl acrylate content in graft copolymer and absorbed dose.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2023

Relaxation dynamics of water in the vicinity of cellulose nanocrystals

Water molecules near cellulose nanocrystals (CNCs; produced via the sulfuric acid-catalyzed hydrolysis of wood pulp) are believed to relax slower than those in the bulk liquid, which may result in unique properties of CNC aqueous dispersions. Herein this study analyzed the polarization behavior of water molecules in CNC aqueous dispersions and other reference samples using a dielectric relaxation spectroscopy (DRS) technique in the microwave frequency range (0.2–20 GHz). As the CNC concentration increases, two slow relaxation components become prominent. The comparison with DRS data of aqueous dispersions of nanoporous silica, polyvinyl alcohol (PVA), and hairy CNC (HCNC) with amorphous chains protruding from both ends suggested that these slow relaxation modes of water near CNC surfaces cannot be attributed to direct hydrogen bonding interactions with the hydroxyl (OH) groups exposed and immobilized at the solid surface. Instead, they are similar to the water molecules interacting with OH groups attached to flexible polymer chains. Molecular dynamics (MD) simulations of the polarization behavior of water near the (110) facet of cellulose Iβ crystals confirmed that the interactions of water molecules with the cellulose crystal surface do not cause slower relaxations in the frequency range studied via the DRS. These results indicated that the CNC surface cannot be depicted with the crystallographic facets of cellulose Iβ; instead, it resembles a polymer-brush surface on which the short glucan residues or fragments of the strong acid-catalyzed hydrolysis process are swollen and extended into the aqueous phase.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2018

Silver Nanoparticles Formed in a Colloidal System and a Polymer Matrix

The growth kinetics and particle-size distribution of Ag particles in a polyvinyl alcohol (PVA) composite, PVA film, and aqueous sol were studied using UV and visible spectroscopy, atomic force microscopy, and dynamic light scattering. A hypsochromic shift (55 nm) of the Ag nanoparticle (NP) surface plasmon absorption maximum was measured on going from the PVA composite to the film. The kinetics of Ag NP formation and their sizes were shown to depend considerably on UV irradiation, ultrasound action, and PVA concentration. It was established that UV irradiation accelerated Ag NP formation in the presence of reductants and destroyed the resulting NPs with a deficit of reductant. Partial destruction of the Ag NPs occurred under the influence of ultrasound whereas ultrasound action after UV irradiation reduced Ag{sup +} on the clusters.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2023

Synthesis and characteristics of porous ceramic tubes: a comparison of centrifugal casting and cold isostatic pressing methods

Short porous ceramic tubes in small quantities are needed for membrane-related research and development efforts and can be synthesized by centrifugal casting (CC) or cold isostatic pressing (CIP) methods. Here, this work evaluates the characteristics of porous ceramic tubes prepared by both methods and provides a strategy for selecting the proper method for ceramic tube fabrication, depending on its application. Samarium-doped ceria (SDC) with an average crystallite size of 10 nm was synthesized by a citrate method and used to make porous SDC tubes by the CC and CIP methods under different conditions. Porous SDC tubes were prepared from an aqueous suspension of the SDC powder with polyvinyl alcohol (PVA) using a cylindrical metallic mold, centrifugated at 4000–6000 rpm, followed by sintering in 1200–1500 °C. SDC tubes were also made by the CIP method from the SDC powder placed inside a cylindrical rubber bag followed by isostatic compression at 1379 bar. The pore structure of the SDC tubes was characterized by helium permeation and liquid nitrogen Archimedes method. Due to high compression pressure giving a low porosity green tube, the CIP method with lower sintering temperature produces SDC tubes with much lower porosity and average pore size and similar tortuosity compared to the CC methods. The CIP method should be used to prepare low porosity or dense ceramic tubes, and the CC method should be used for preparing high-porosity ceramic tubes or tubes with pore gradient tube wall.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Block copolymer-mediated synthesis of TiO2/RuO2 nanocomposite for efficient oxygen evolution reaction

Abstract An amphiphilic block copolymer, poly (styrene-2-polyvinyl pyridine-ethylene oxide), was used as a structure-directing and stabilizing agent to synthesize TiO 2 /RuO 2 nanocomposite. The strong interaction of polymers with metal precursors led to formation of a porous heterointerface of TiO 2 /RuO 2 . It acted as a bridge for electron transport, which can accelerate the water splitting reaction. Scanning electron microscopy, energy-dispersive X -ray spectroscopy, transmission electron microscopy, and X -ray diffraction analysis of TiO 2 /RuO 2 samples revealed successful fabrication of TiO 2 /RuO 2 nanocomposites. The TiO 2 /RuO 2 nanocomposites were used to measure electrochemical water splitting in three-electrode systems in 0.1-M KOH. Electrochemical activities unveil that TiO 2 /RuO 2 -150 nanocomposites displayed superior oxygen evolution reaction activity, having a low overpotential of 260 mV with a Tafel slope of 80 mVdec −1 . Graphical abstract

36 MATERIALS SCIENCE↗
DOE OSTI2017

Study of Optical Properties of Polymeric Materials Subjected to Degradation

Results of a study on polyethylene, polyvinyl chloride, latex and polypropylene films by photocolorimetry are described. The polymeric films were subjected to destructive environmental factors as ozone, ultra-violet irradiation and γ-radiation. It is shown that these factors can lead to a reduction or an increase of transparency. This fact is due to the mechanisms of crosslinking, crystallization and destruction of macromolecules. Correlation between the photocolorimetry data and distributions of relaxation times of a nuclear magnetic resonance of protons in different sites of the polymeric network received earlier is established.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Exfoliation and Decoration of Graphene Sheets with Silver Nanoparticles and Their Antibacterial Properties

High quality graphene sheets (GRP) have been exfoliated using facile one pot method through direct ultrasonication of graphite in the presence of polyvinyl alcohol. The GRP were decorated with silver nanoparticles (AgNPs) producing graphene–silver nanoparticle composites. The effect of variation of graphite and silver salt mass ratios on the morphology and performance of produced composites was studied. The size of AgNPs decorated on GRP has been tuned with synthesis method optimization. The average size of AgNPs was found to be in the range of 8.6–15.6 nm. Cotton–polyester blend textile fabrics were treated with the new smart developed composite as antibacterial agent producing new composites. A significant inhibition of bacterial growth has been observed for graphene–silver nanoparticle composite and the antibacterial efficiency was optimized. The clear inhibition zone for textiles treated with new developed composite and AgNPs alone was recorded as 12 and 1.75 mm respectively, achieving more than six fold improvement.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Green Synthesis of Fe{sub 3}O{sub 4}/Cellulose/Polyvinyl Alcohol Hybride Aerogel and Its Application for Dye Removal

A novel Fe{sub 3}O{sub 4}/cellulose–polyvinyl alcohol (PVA) aerogel was successfully synthesized by an eco-friendly and facile method in this work. Cellulose/PVA matrix was prepared through an environmental friendly physical cross-linking process and further in-situ decorated with Fe{sub 3}O{sub 4}. Series of Fe{sub 3}O{sub 4} decorated aerogels were prepared and the effects of Fe{sub 3}O{sub 4} nanoparticles (NPs) on the aerogels were systematic investigated. As-prepared aerogels exhibited desirable properties including nanostructure, relatively high porosity, improved mechanical and superparamagnetism. The TEM results showed that Fe{sub 3}O{sub 4} NPs were integrated in the three-dimensional matrix of cellulose/PVA with a diameter of 9–12 nm. Furthermore, the mechanical strength of the aerogels was significantly enhanced after the introduction of Fe{sub 3}O{sub 4} NPs. Meanwhile, the obtained Fe{sub 3}O{sub 4}/cellulose/PVA aerogel exhibited excellent adsorption performance toward methyl blue dye, and can be reused through fenton-like catalysts oxidative degradation of organic dye in H{sub 2}O{sub 2} solution. Therefore, they will have a great potential application as eco-friendly and economical adsorbents.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Water Remediation: PVA-Based Magnetic Gels as Efficient Devices to Heavy Metal Removal

Scientific and technological researches are devoted to obtain materials capable of retaining different kinds of pollutants, contributing to contamination solutions. In this context, hydrogels have emerged as great candidates because of their excellent absorption properties as well as good mechanical, thermal and chemical properties. More specifically, ferrogels (magnetic gels) present the extra advantage of being easily manipulated by a permanent magnet. Here, we present the results derived from the application of ferrogels as efficient tools to extract heavy metal pollutants from wastewater samples. The gels were prepared following the method of freezing and thawing of a polyvinyl alcohol aqueous solution with magnetic nanoparticles coated with polyacrylic acid. Ferrogels were fully characterized and their ability to retain Cu{sup 2+} and Cd{sup 2+}, as model heavy metals, was studied. Thus kinetics and mechanisms of adsorption were evaluated and modeled. The concentration of MNPs on the PVA matrix was key to improve the adsorption capability (approximately the double of retention is improved by the MNPs addition). The adsorption kinetics was determined as pseudo-second order model, whereas the Langmuir model was the most appropriate to explain the behavior of the gels. Finally reuse ability was evaluated to determine the real potential of these materials, the ferrogels demonstrated high efficiency up to about five cycles, retaining about 80–90% of their initial adsorption capability. All the results indicated that the materials are promising candidates able to compete with the commercial technology regarding to water remediation.

36 MATERIALS SCIENCE↗
DOE OSTI2018

PVA Based Ternary Nanocomposites with Enhanced Properties Prepared by Using a Combination of Rice Starch Nanocrystals and Silver Nanoparticles

Ternary nanocomposite films exhibiting better properties were prepared by incorporating two different nanoparticles such as rice starch nanocrystals (RSN) and silver nanoparticles (AgNPs) together in polyvinyl alcohol (PVA) matrix at various concentrations. The morphological evaluation using atomic force microscopy revealed that the particle size of RSN nanoparticles varied from 50 to 125 nm. The nanocomposite films made using these nanoparticles were evaluated for its chemical, mechanical and thermal properties. FTIR spectra of the films revealed some specific vibrational bands of RSN along with the characteristic bands of PVA. The mechanical property analysis of nanocomposite films indicated better tensile strength and elongation properties, which can be attributed to the strong interaction of PVA with RSN and AgNPs. The thermal properties of these films were also evaluated. These ternary nanocomposites exhibited superior mechanical properties, which is very much beneficial as far as the end use applications are concerned.

77 NANOSCIENCE AND NANOTECHNOLOGY↗