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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 883 records · Page 49
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

2D Ising Model for Adsorption–induced Enantiopurification of Racemates

Mechanisms for the spontaneous transformation of achiral chemical systems into states of enantiomeric purity have important ramifications in modern pharmacology and potential relevance to the origins of homochirality in life on Earth. Such mechanisms for enantiopurification are needed for production of chiral pharmaceuticals and other bioactive compounds. Previously proposed chemical mechanisms leading from achiral systems to near homochirality are initiated by a symmetry–breaking step resulting in a minor excess of one enantiomer via statistical fluctuations in enantiomer concentrations. Subsequent irreversible processes then amplify the majority enantiomer concentration while simultaneously suppressing minority enantiomer production. Herein, equilibrium adsorption of amino acid enantiomer mixtures onto chiral and achiral surfaces reveals amplification of surface enantiomeric excess relative to the gas phase; i. e. enantiopurification of chiral adsorbates by adsorption. Furthermore, this adsorption–induced amplification of enantiomeric excess is shown to be well–describe by the 2D Ising model. More importantly, the 2D–Ising model predicts formation of homochiral monolayers from adsorption of racemic mixtures or prochiral molecules on achiral surfaces; i.e. enantiopurification with no apparent chiral driving force.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Synthesis of Bis-1,2,4-triazines via Telescoped Condensation of [1,10]-Phenanthroline-2,9-dicarbonitrile with Aromatic 1,2-Dicarbonyls

Efficient separation of minor actinides from spent nuclear fuel remains a formidable challenge. As part of ongoing efforts to identify effective ligands for separation of toxic radionuclides, a series of bis-1,2,4-triazines, three novel, have been prepared in this paper from [1,10]-phenanthroline-2,9-dicarbonitrile in two-telescoped steps without additives, complicated workups, prolonged reaction times, or additional purification.

Tai, Serene↗
DOE OSTI2017

Assessing the oxidation states and structural stability of the Ce analogue of brannerite

The Ce-containing analogue of brannerite (ie, UTi2O6) was previously considered to be stoichiometric (ie, CeTi2O6); however, it has recently been determined that the material is O deficient. This oxygen-deficient material has been suggested to be charged balanced by the presence of a minor concentration of Ce3+ or by the A-site being cation deficient with the Ce oxidation state being 4+. A variety of Ti-containing oxides (including brannerite) have been investigated as potential nuclear wasteforms, and it is necessary to understand the electronic structure of a proposed nuclear wasteform material as well as how the structure responds to radiation from incorporated waste elements. The radiation resistance of a material can be simulated by ion implantation. The objective of this study was to confirm the Ce oxidation state in the cation- and oxygen-deficient material (ie, Ce0.94Ti2O6 - δ) and to determine how radiation damage affects this material. X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge spectroscopy were used to study Ce0.94Ti2O6 - δ before and after being implanted with 2 MeV Au- ions. Analysis of the Ce 3d XPS spectra from the as-synthesized samples by using a previously developed fitting method has unequivocally shown that Ce adopts both 4+ (major) and 3+ (minor) oxidation states, which was confirmed by examination of magnetic susceptibility data. Analysis of XPS and X-ray absorption near-edge spectroscopy spectra from ion-implanted materials showed that both Ce and Ti were reduced because of radiation damage and that the local coordination environments of the cations are greatly affected by radiation damage.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Long-Term Degradation of Passivated Emitter and Rear Contact Silicon Solar Cell under Light and Heat

Advanced designs enable high-efficiency solar cells; however, more complex structures create new long-term stability concerns. Herein, the long-term degradation processes affecting advanced silicon solar cells using laboratory-based illumination and heating over hundreds of hours are investigated. The activation energy for the degradation of voltage is estimated and the degradation rates to normal solar cell operating temperature ranges are extrapolated. The cell degradation observed at high temperatures in the lab is kinetically similar to the process affecting field-deployed modules contributing to 0.37% year-1 of annualized degradation. Electroluminescence and photoluminescence mapping show that the degradation is dominated by minority carrier lifetime reduction. Suns-open-circuit voltage and light beam-induced current results indicate that the degradation could result from passivation degradation at the surface or defect formation in the near-subsurface region, leading to increased minority carrier recombination. This work highlights a long-term degradation process under elevated temperature and illumination that may continue to affect cells in an irreversible manner that is separate from recoverable light-induced degradation and light- and elevated temperature-induced degradation.

14 SOLAR ENERGY↗
DOE OSTI2015

Erratum to: Measurement of the inclusive jet cross-section in proton-proton collisions at $ \sqrt{s}=7 $ TeV using 4.5 fb -1 of data with the ATLAS detector

It was found that the non-perturbative corrections calculated using Pythia with the Perugia 2011 tune did not include the effect of the underlying event. The affected correction factors were recomputed using the Pythia 6.427 generator. These corrections are applied as baseline to the NLO pQCD calculations and thus the central values of the theoretical predictions have changed by a few percent with the new corrections. This has a minor impact on the agreement between the data and the theoretical predictions. Figures 2 and 6 to 13, and all the tables have been updated with the new values. A few sentences in the discussion in sections 5.2 and 9 were altered or removed.[Figure not available: see fulltext.]

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Duodenal obstruction induced by retroperitoneal progression of bladder cancer: a report of two cases

Bladder cancer usually forms a papillary structure. Progression along the cavity or membranous structures surrounding the bladder, rectum, or retroperitoneum without formation of a discrete mass is rare. We here present two patients with duodenal obstruction caused by retroperitoneal progression of bladder cancer, in both of whom computed tomography revealed bladder and rectal wall thickening with a malignant target sign, thickened mesorectal fascia with abnormal tissue stranding, and increased perirectal fat density. Both cancers progressed despite treatment, as indicated by faint abnormal tissue stranding and increased retroperitoneal fat density along the retromesenteric plane from the pelvis to the duodenum. Subsequently, both patients developed obstruction in the horizontal portion of the duodenum, still without formation of a mass lesion. These two patients highlight the challenges associated with retroperitoneal invasion by bladder cancer in the absence of a mass lesion and underscore the importance of considering cancer progression in patients with bowel obstruction, even when there is no obvious mass lesion and/or only minor retroperitoneal findings. Progression along the retromesenteric plane may be the key pathway via which progressive bladder cancer results in duodenal obstruction without or with a minor mass lesion.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Carotid Artery Stenting Trials: Conduct, Results, Critique, and Current Recommendations

The carotid stenting trialists have demonstrated persistence and determination in comparing an evolving technique, carotid artery stenting (CAS), against a mature and exacting standard for carotid revascularisation, carotid endarterectomy (CEA). This review focuses on their endeavours. A total of 12 1-on-1 randomised trials comparing CAS and CEA have been reported; 6 of these can be considered major, and 5 of these reflect (in part) current CAS standards of practice and form the basis of this review. At least 18 meta-analyses seeking to compare CAS and CEA exist. These are limited by the quality and heterogeneity of the data informing them (e.g., five trials were stopped prematurely such that they collectively failed to reach recruitment target by >4000 patients). The Carotid Stenting Trialists' Collaboration Publication represents a prespecified meta-analysis of European trials that were sufficiently similar to allow valid conclusions to be drawn; these trials and conclusions will be explored. When the rate of myocardial infarction (MI) is rigorously assessed, CAS and CEA are equivalent for the composite end point of stroke/death and MI, with more minor strokes for CAS and more MIs for CEA. These outcomes have a discrepant impact on quality of life and subsequent mortality. The all-stroke death outcomes for patients <70 years old are equivalent, with more minor strokes occurring in the elderly during CAS than CEA. There are significantly more severe haematomas and cranial nerve injuries after CEA. The influence of experience on outcome cannot be underestimated.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Complications of Microwave Ablation for Liver Tumors: Results of a Multicenter Study

Purpose: New technologies for microwave ablation (MWA) have been conceived, designed to achieve larger areas of necrosis compared with radiofrequency ablation (RFA). The purpose of this study was to report complications by using this technique in patients with focal liver cancer. Methods: Members of 14 Italian centers used a 2.45-GMHz generator delivering energy through a cooled miniature-choke MW antenna and a standardized protocol for follow-up. They completed a questionnaire regarding number and type of deaths, major and minor complications and side effects, and likelihood of their relationship to the procedure. Enrollment included 736 patients with 1.037 lesions: 522 had hepatocellular carcinoma with cirrhosis, 187 had metastases predominantly from colorectal cancer, and 27 had cholangiocellular carcinoma. Tumor size ranged from 0.5 to 10 cm. In 13 centers, the approach used was percutaneous, in 4 videolaparoscopic, and in 3 laparotomic. Results: No deaths were reported. Major complications occurred in 22 cases (2.9%), and minor complications in 54 patients (7.3%). Complications of MWA do not differ from those RFA, both being based on the heat damage. Conclusion: Results of this multicenter study confirmed those of single-center experiences, indicating that MWA is a safe procedure, with no mortality and a low rate of major complications. The low rate of complications was probably due to precautions adopted, knowing in advance possible risk conditions, on the basis of prior RFA experience.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Percutaneous Radiofrequency Ablation of a Small Renal Mass Complicated by Appendiceal Perforation

Percutaneous radiofrequency ablation (RFA) has gained wide acceptance as nephron-sparing therapy for small renal masses in select patients. Generally, it is a safe procedure with minor morbidity and acceptable short-term oncologic outcome. However, as a result of the close proximity of vital structures, such as the bowel, ureter, and large vessels, to the ablative field, complications regarding these structures may occur. This is the first article describing appendiceal perforation as a complication of computed tomography-guided RFA despite hydrodissection. When performing this innovative and promising procedure one should be aware of the possibility of particular minor and even major complications.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Suitability of Exoseal Vascular Closure Device for Antegrade Femoral Artery Puncture Site Closure

Purpose. To assess the efficacy and safety of the Exoseal vascular closure device for antegrade puncture of the femoral artery. Methods. In a prospective study from February 2011 to January 2012, a total of 93 consecutive patients received a total of 100 interventional procedures via an antegrade puncture of the femoral artery. An Exoseal vascular closure device (6F) was used for closure in all cases. Puncture technique, duration of manual compression, and use of compression bandages were documented. All patients were monitored by vascular ultrasound and color-coded duplex sonography of their respective femoral artery puncture site within 12 to 36 h after angiography to check for vascular complications. Results. In 100 antegrade interventional procedures, the Exoseal vascular closure device was applied successfully for closure of the femoral artery puncture site in 96 cases (96 of 100, 96.0 %). The vascular closure device could not be deployed in one case as a result of kinking of the vascular sheath introducer and in three cases because the bioabsorbable plug was not properly delivered to the extravascular space adjacent to the arterial puncture site, but instead fully removed with the delivery system (4.0 %). Twelve to 36 h after the procedure, vascular ultrasound revealed no complications at the femoral artery puncture site in 93 cases (93.0 %). Minor vascular complications were found in seven cases (7.0 %), with four cases (4.0 %) of pseudoaneurysm and three cases (3.0 %) of significant late bleeding, none of which required surgery. Conclusion. The Exoseal vascular closure device was safely used for antegrade puncture of the femoral artery, with a high rate of procedural success (96.0 %), a low rate of minor vascular complications (7.0 %), and no major adverse events.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Complications and Reinterventions in Uterine Artery Embolization for Symptomatic Uterine Fibroids: A Literature Review and Meta Analysis

To perform a literature review of the spectrum of complications associated with UAE relative to surgery and compare the risk of reintervention as well as minor, major, and overall complications. Literature review was conducted in PubMed, MEDLINE, Cochrane, and CINAHL databases, and meta-analysis was performed. In randomized clinical trials, common complications were discharge and fever (4.00 %), bilateral uterine artery embolization (UAE) failure (4.00 %), and postembolization syndrome (2.86 %). Two trials showed a significantly decreased risk in major complications with UAE, with odds ratios (ORs) of 0.07143 (0.009426-0.5413) and 0.5196 (0.279-0.9678). None of the trials showed a significant difference in OR for minor complications of UAE. None of the trials showed a significant difference in risk for overall complications of UAE. Three trials showed a significantly increased risk for reintervention with UAE with ORs of 10.45 (2.654-41.14), 2.679 (1.289-5.564), and 9.096 (1.269-65.18). In 76 nonrandomized studies, common complications were amenorrhea (4.26 %), pain (3.59 %), and discharge and fever (3.37 %). In 41 case studies, common complications were discharge and fever (n = 22 cases), repeat UAE (n = 6 cases), and fibroid expulsion (n = 5 cases). Overall, UAE has a significantly lower rate of major complications relative to surgery, but it comes at the cost of increased risk of reintervention in the future. Educating patients about the rate and types of complications of UAE versus surgery, as well as the potential for reintervention, should help the patient and clinician come to a reasoned decision.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Renoduodenal Fistula After Transcatheter Embolization of Renal Angiomyolipoma

Transcatheter embolization of renal angiomyolipomas is a routinely performed, nephron-sparing procedure with a favorable safety profile. Complications from this procedure are typically minor in severity, with postembolization syndrome the most common minor complication. Abscess formation is a recognized but uncommon major complication of this procedure and is presumably due to superinfection of the infarcted tissue after arterial embolization. In this case report, we describe the formation of a renoduodenal fistula after embolization of an angiomyolipoma, complicated by intracranial abscess formation and requiring multiple percutaneous drainage procedures and eventual partial nephrectomy.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Carotid Stenting with Distal Protection in High-Surgical-Risk Patients: One-Year Results of the ASTI Trial

PurposeThis prospective, multicenter, nonrandomized study evaluated the periprocedural and 1-year outcomes in high-surgical-risk patients with carotid artery stenosis treated with the Adapt Carotid Stent plus FilterWire EZ distal protection catheter (Boston Scientific Corporation, Natick, MA).Materials and MethodsThe study enrolled 100 patients (32 symptomatic, 63 asymptomatic, 5 unknown) at high risk for carotid endarterectomy due to prespecified anatomical criteria and/or medical comorbidities. Thirty-day and 1-year follow-up included clinical evaluation, carotid duplex ultrasound, and independent neurologic and NIH stroke scale assessments. One-year endpoints included the composite rate of major adverse events (MAE), defined as death, stroke, and myocardial infarction (MI) and the rates of late ipsilateral stroke (31–365 days), target lesion revascularization, and in-stent restenosis.ResultsOf the 100 enrolled patients, technical success was achieved in 90.9 % (90/99). The 30-day MAE rate (5.1 %) consisted of major stroke (2.0 %) and minor stroke (3.1 %); no deaths or MIs occurred. The 1-year MAE rate (12.2 %) consisted of death, MI, and stroke rates of 4.4, 3.3, and 8.9 %, respectively. Late ipsilateral stroke (31–365 days) rate was 1.1 %. Symptomatic patients had higher rates of death (11.1 vs. 1.7 %) and MI (7.4 vs. 1.7 %), but lower rates of major (7.4 vs. 10.0 %) and minor stroke (0.0 vs. 6.7 %), compared with asymptomatic patients.ConclusionResults through 1 year postprocedure demonstrated that carotid artery stenting with Adapt Carotid Stent and FilterWire EZ is safe and effective in high-risk-surgical patients.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Percutaneous MR-Guided Cryoablation of Morton’s Neuroma: Rationale and Technical Details After the First 20 Patients

ObjectivesThe purpose of this study is to discuss technical aspects and rationales of magnetic resonance (MR)-guided cryoablation (CA) of Morton’s neuroma (MN); preliminary clinical experience is also retrospectively reviewed.MethodsProcedures were performed under local anaesthesia on an outpatient basis. Lesion size and location, procedural (technical success, procedural time, complications) and clinical outcomes (patient satisfaction according to a four-point scale, residual pain according to a 0–10 visual analogue scale and instances of “stump neuroma”) were assessed via chart review and cross-sectional telephone survey after the 20th case.ResultsTwenty patients (15 female, 5 male; mean age 50.3 years) were included; 24 MN (mean size 12.7 mm) were treated. Technical success was 100 %. Mean procedural time was 40.9 ± 10.4 min (range 35–60). One minor complication (superficial cellulitis) was reported (4.2 %). Follow-up (mean 19.7 months) was available for 18/24 MN. Patient satisfaction on a per-lesion basis was as follows: “completely satisfied” in 77.7 %, “satisfied with minor reservations” in 16.6 % and “satisfied with major reservations” in 5.7 % of cases. Mean pain score at last follow-up post-CA was 3.0. No instances of “stump neuroma” were reported.ConclusionsMR-guided CA of MN is a novel therapy which appears technically feasible. Clinical advantages of the procedure are high patient satisfaction, reduced risk of “stump neuroma” syndrome and good patient tolerance on an outpatient basis. Further, prospective studies are needed to confirm these encouraging results.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Infrared signature of micro-hydration in the organophosphate sarin: An ab initio study

The infrared (IR) spectra of micro-hydrated Sarin•(H 2 O) n clusters containing between one and four explicit waters have been studied using ab initio density functional theory (DFT) methods. The phosphate group P=O bond vibration region (~1270 to 1290 cm –1 ) revealed the largest frequency variation with hydration, with a frequency red shift reflecting the direct hydrogen bond formation between the P=O of Sarin and water. Small variations to the P-F stretch (~810 to 815 cm –1 ) and the C-O-P vibrational modes (~995 to 1004 cm –1 ) showed that the water interactions with these functional groups were minor, and that the structures of Sarin were not extensively perturbed in the hydrated complexes. Increasing the number of explicit hydration waters produced only small vibrational changes in the lowest free energy complexes. These minor changes were consistent with a single water-phosphate hydrogen bond being the dominant structure, though a second water-phosphate hydrogen bond was observed in some complexes and was identified by an additional red shift of the P=O bond vibration. As a result, the H 2 O•H 2 O vibrational modes (~3450 to 3660 cm –1 ) increased in complexity with higher hydration levels and reflect the extended hydrogen bonding networks formed between the explicit waters in the hydrated Sarin clusters.

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

Oxidation of Cyclohexene Catalyzed by Nanoporous Au(Ag) in Liquid Phase

Nanoporous gold with minor silver content has been identified as a new type of gold based catalyst for selective oxidation of cyclohexene with molecular oxygen in liquid. By oxidation of the leached nanoporous gold foils in ozone, the minor silver content was oxidized in this paper to form silver oxide nanoclusters on the surface of nanoporous gold. With further treatment in methanol, the surface silver oxide was reduced and surface alloy was formed on gold ligaments. Both nanoporous gold treated with ozone only and the one with ozone and then methanol are very active for selective oxidation of cyclohexene with molecular oxygen in liquid of cyclohexene with a turn-over-frequency (TOF) of 0.55–0.99 molecules per surface Au atom per second under a solvent-free and initiator- free condition. The total selectivity for production of 2-cyclohexene-1-one, 2-cyclohexene-1-ol, and cyclohexene oxide was increased from 57.5 % to 80.8 % by an additional treatment of nanoporous gold in methanol after activation in zone. Finally, the correlation of catalytic selectivity for the production of the three products and corresponding surface chemistry of ligament suggests that (1) the formed Au–Ag alloy surface is favorable for the formation of 2-cyclohexen-1-one, 2-cyclohexene-1-ol, and cyclohexene oxide and (2) the surface silver oxide is favorable for the production of cyclohexenyl hydroperoxide.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Understanding heterogeneity in Genesis diamond-like carbon film using SIMS analysis of implants

An amorphous diamond-like carbon film deposited on silicon made at Sandia National Laboratory by pulsed laser deposition was one of several solar wind (SW) collectors used by the Genesis Mission (NASA Discovery Class Mission #5). The film was ~1 μm thick, amorphous, anhydrous, and had a high ratio of sp 3 –sp 2 bonds (>50%). For 27 months of exposure to space at the first We passively irradiated lagrange point, the collectors, with SW (H fluence ~2 × 10 16 ions cm -2 ; He fluence ~8 × 10 14 ions cm -2 ). The radiation damage caused by the implanted H ions peaked at 12–14 nm below the surface of the film and that of He about 20–23 nm. To enable quantitative measurement of the SW fluences by secondary ion mass spectroscopy, minor isotopes of Mg ( 25 Mg and 26 Mg) were commercially implanted into flight-spare collectors at 75 keV and a fluence of 1 × 10 14 ions cm -2 . Furthermore, the shapes of analytical depth profiles, the rate at which the profiles were sputtered by a given beam current, and the intensity of ion yields are used to characterize the structure of the material in small areas (~200 × 200 ± 50 μm). Data were consistent with the hypothesis that minor structural changes in the film were induced by SW exposure.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Binding Studies of Isoxsuprine Hydrochloride to Calf Thymus DNA Using Multispectroscopic and Molecular Docking Techniques

In the present work, the interaction of Isoxsuprine (ISX) with Calf thymus DNA (ct-DNA) under physiological conditions (Tris–HCl buffer of pH 7.4) was investigated by using electronic absorption, circular dichroism, viscosity, electrochemical studies, fluorescence techniques, salt effect studies and computational studies. Competitive fluorimetric studies with Hoechst 33258 have shown that ISX exhibit the ability to displace the DNA-bound Hoechst 33258, indicating that it binds to ct-DNA in strong competition with Hoechst 33258 for the minor groove binding. Furthermore, the resulting data showed that ISX cannot displace methylene blue or acridine orange, which are the common intercalator molecules. The viscosity of ct-DNA solution was almost unchanged on addition of ISX and circular dichroism (CD) spectra of ct-DNA showed small changes in the presence of ISX which is in agreement with groove binding mode of interaction. Thus all above studies showed that the ISX drug binds to ct-DNA in a groove binding mode.The salt-effect studies showed the non-electrostatic nature of binding of ISX to ct-DNA. Moreover, molecular docking results support the above experimental data and suggest that ISX prefers to bind on the minor groove of ct-DNA.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗