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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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All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Synthesis, Photophysical, Electrochemical and Thermal Investigation of Anthracene Doped 2-Naphthol Luminophors and their Thin Films for Optoelectronic Devices

A series of novel luminophors of 2-naphthol by doping anthracene were prepared using conventional solid state reaction technique. The photophysical, electrochemical and thermal properties were studied by Fluorescence spectroscopy, XRD, SEM, TGA-DSC and by Cyclic Voltammetry techniques. The thin films were characterized by Fluorescence spectroscopy. XRD study of fine grained powders exhibited sharp peaks which specify crystallinity and homogeneity of the doped luminophors. The fluorescence spectra of doped 2-naphthol exhibited emission of anthracene at 413 nm i.e. blue emission with instantaneous fluorescence quenching of 2-NP due to excitation energy transfer (EET). Electrochemical data specify that the HOMO and LUMO energy levels of the synthesized luminophors are in the range of 5.55–5.71 eV and 3.03–3.24 eV, respectively. TGA-DSC study confirmed thermal stability of prepared luminophors. Hence, overall study proposes that these luminophors seems applicable to be used as n-type materials for Optoelectronic devices.

36 MATERIALS SCIENCE↗
DOE OSTI2018

MR Imaging of Patients with Cardiac Implantable Electronic Devices (CIEDs): Implementing a Program and Optimizing CMR

Purpose of review: How to implement a program for MRI in patients with conditional and non-conditional (“legacy”) CIED. How to optimize safety and image quality in CMR? What the radiologists need to know: device programming, pre- and post-MRI CIED parameters. Recent findings: New Center for Medicare and Medicaid Services (CMS) guidelines have opened MRI to many patients with nonconditional devices. Newer pulse sequences for cardiac MRI (CMR) in device patients, including modified cine, late gadolinium enhancement and T1 mapping sequences, have resulted in improved image quality in device patients. We present several cases of CMR in device patients, including imaging of leadless pacemakers subcutaneous ICDs. Imaging pitfalls/artifacts in CMR interpretation are also presented. Summary: An organized institutional workflow with an established protocol involving proper patient screening, device programming, scan monitoring, and pre- and post-ICD interrogation minimizes risk in patients with conditional and non-conditional CIEDs. Although rare, significant changes in lead performance, power-on/reset, inappropriate pacing or ICD discharges and battery voltage depletion should be documented. High-quality scans with accurate scar characterization in CIED patients require the use of wideband sequences. CMS has recently acknowledged MRI as a reasonable test necessary for the diagnosis and treatment of beneficiaries with implanted CIEDs, improving the financial prospects and encouraging future developments.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2023

Handheld Raman Spectrometers: Assessment Report

In April 2022 the National Urban Security Technology Laboratory’s System Assessment and Validation for Emergency Responders program conducted an operational assessment of ten commercially available handheld Raman spectrometers. Additionally, prior to the operational assessment, the Pacific Northwest National Laboratory conducted laboratory testing of the devices, including scanning a number of samples in various containers. This report summarizes the results of the assessment.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2024

General Testing Setup for Hyperelastic Transducers-DEEC-Tec & Marine Renewable Energy: Preprint

Distributed embedded energy conversion technologies (DEEC-Tec), an emerging domain for ocean wave energy conversion technology, is showing promise for a range of applications. Research is being conducted at the National Renewable Energy Laboratory that leverages this domain to investigate the potential of ocean wave energy converters (WECs) constructed from hyperelastic forms of distributable and embeddable energy transducers. These transducers are available in forms such as disks, rectangles, or hexagons and can be combined in various ways to form energy-producing metamaterials and flexible WECs. DEEC-Tec, therefore, could open doors that enhance ocean wave energy conversion in ways not previously thought possible by allowing for many WEC topologies and morphologies. However, the same diversity and adaptability pose challenges for the development of these DEEC-Tec-oriented hyperelastic transducers. A commercial tensile testing setup was not found that was adaptable enough to accommodate the varied transducers while providing precise force control, range of motion, and noncontact data collection. Because of this lack, a comprehensive test rig was designed in house to be used with a 3D laser scanning device-providing contactless measurements while also allowing for different geometries and various uniaxial loadings. This paper and presentation will discuss these unique challenges and the processes for overcoming them to provide a robust and general testing setup for hyperelastic transducers, of any form, for the DEEC-Tec marine renewable energy domain.

DEEC-Tec↗
DOE OSTI2022

Effect of oxide layer growth conditions on radiation detection performance of Ni/SiO 2 /epi-4H-SiC MOS capacitors

We report high resolution radiation detection has been demonstrated using Ni/SiO2/n-4H-SiC metal-oxidesemiconductor vertical capacitors fabricated using highly crystalline 4H-SiC epilayers. The oxide layers have been grown thermally using two different approaches: i) in-air, and ii) oxygen-ambience oxidation. The devices fabricated using the former method exhibited dark currents one order of magnitude higher than that in the latter. The observed difference has been attributed to the back-contact series resistance and capacitance. Regardless of the difference in the device parameters, detectors prepared using both of the methods exhibited very high energy resolutions of ≤ 0.5% for 5486 keV alpha particles emitted by an 241Am radioisotope. Capacitance mode deep level transient spectroscopic (DLTS) studies revealed similar type of electrically active defects along with Z1/2 and EH5 deep level defects in both the types of devices. The DLTS scans also revealed positive polarity peaks in these devices which indicate emission from minority carrier trap centers. The activation energy corresponding to the peak was found to be ~1.2 eV which has been assigned to HK3 defects responsible for hole trapping in 4H-SiC. The possibility of appearance of the positive peak due to non-negligible impedance of the back-contact has been ruled out based on the observation that the centroid of the observed peak did not change with detectors having different device parameters.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Scanning method for screening of electronic devices

A visualization method for screening electronic devices is provided. In accordance with the disclosed method, a probe is applied to a grid of multiple points on the circuit, and an output produced by the circuit in response to the stimulus waveform is monitored for each of multiple grid points where the probe is applied. A power spectrum analysis (PSA) produces a power spectrum amplitude, in each of one or more frequency bins, on the monitored output for each of the multiple grid points. The PSA provides a respective pixel value for each of the multiple grid points. An image is displayed, in which image portions representing the multiple grid points are displayed with the respective pixel values.

47 OTHER INSTRUMENTATION↗
DOE OSTI2024

Ultrasound Interim cyber-physical research evaluation

Recent events have presented Medical Practitioners with concerns about safety and privacy implications associated with GE’s VScan MIot Ultrasound Device. Concerns relate to the devices potential risk to broadcast location data that can pose serious risks to device users and patients. This report was commission in collaboration with Augusta University to determine if device concerns pose real threat to operators and patients. In effort to ensure all potential threat vectors are targeted, the initial step was to analyze the supply chain. Here the devices are CT scanned to look for any hardware anomalies that could present threat vectors to users of these devices. (See SRNL-STI-2024-00225 for detailed analysis). No anomalies were found associated with the hardware utilized within the GE VScan Air.

42 ENGINEERING↗
DOE OSTI2019

Low-Resistance, High-Yield Electrical Contacts to Atom Scale Si:P Devices Using Palladium Silicide

Scanning tunneling microscopy (STM) enables the fabrication of two-dimensional δ-doped structures in Si with atomistic precision, with applications from tunnel field-effect transistors to qubits. The combination of a very small contact area and the restrictive thermal budget necessary to maintain the integrity of the δ layer make developing a robust electrical contact method a significant challenge to realizing the potential of atomically precise devices. We demonstrate a method for electrical contact using Pd 2 Si formed at the temperature of silicon overgrowth (250 °C), minimizing the diffusive impact on the δ layer. Here, we use the transfer length method to show our Pd 2 Si contacts have very high yield (99.7% +0.2% –1.5%) and low resistivity (272 ± 41 Ω μm) in contacting mesa-etched Si:P δ layers. We also present three terminal measurements of low contact resistance (<1 kΩ) to devices written by STM hydrogen depassivation lithography with similarly high yield (100% +0% –3.2%).

2-dimensional systems↗
DOE OSTI2022

Imaging gate-tunable Tomonaga–Luttinger liquids in 1H-MoSe 2 mirror twin boundaries

One-dimensional electron systems exhibit fundamentally different properties than higher-dimensional systems. For example, electron-electron interactions in one-dimensional electron systems have been predicted to induce Tomonaga-Luttinger liquid behaviour. Naturally occurring grain boundaries in single-layer transition metal dichalcogenides exhibit one-dimensional conducting channels that have been proposed to host Tomonaga-Luttinger liquids, but charge density wave physics has also been suggested to explain their behaviour. Clear identification of the electronic ground state of this system has been hampered by an inability to electrostatically gate such boundaries and tune their charge carrier concentration. Here we present a scanning tunnelling microscopy and spectroscopy study of gate-tunable mirror twin boundaries in single-layer 1H-MoSe 2 devices. Gating enables scanning tunnelling microscopy and spectroscopy for different mirror twin boundary electron densities, thus allowing precise characterization of electron-electron interaction effects. Visualization of the resulting mirror twin boundary electronic structure allows unambiguous identification of collective density wave excitations having two velocities, in quantitative agreement with the spin-charge separation predicted by finite-length Tomonaga-Luttinger liquid theory.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Analysis of the IBL and LBNL irradiated PIN and PN diodes

This report is a follow-up to the previous report on the difference between high fluence, high and low flux irradiations. There was a discrepancy in the data for the LBNL irradiated S5821 PIN diodes. There were diodes irradiated in the two batches (high and low flux) with the same flux and fluence for reference (lell ions/cm 2 /shot and 5, 10, and 20 ions/cm 2 total flux). Although these diodes should have the same electrical characteristics their leakage currents were different by a factor of 5-6 (batch 2 was larger). Also, the C-V measurements showed drastically different results. It was speculated that these discrepancies were due to one of the following two reasons: 1. Different times elapsed between radiation and characterization. 2. Different areas were irradiated (roughly half of the diodes were covered during irradiation). To address the first concern, we annealed the devices according to the ASTM standard [1]. The differences remained the same. To determine the irradiated area, we performed large area IBIC scans on several devices. Error! Reference source not found. below shows the IBIC maps of two devices one from each batch. The irradiated areas are approximately the same.

42 ENGINEERING↗
DOE OSTI2023

First Detection of 120 GeV Protons with Superconducting Nanowire Detectors

We report the test results for a 120 GeV proton beam incident on superconducting nanowire particle detectors of various wire sizes. NbN devices with the same sensitive area were fabricated with different wire widths and tested at a temperature of 3 K. The relative detection efficiency was extracted from bias current scans for each device. The results demonstrate efficient detection of high energy protons for wire widths less than 400 nm. These results are particularly relevant for novel applications at accelerator facilities, such as the Electron-Ion Collider, where cryogenic cooling is readily available.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2023

In operando cryo-STEM of pulse-induced charge density wave switching in TaS 2

The charge density wave material 1T-TaS 2 exhibits a pulse-induced insulator-to-metal transition, which shows promise for next-generation electronics such as memristive memory and neuromorphic hardware. However, the rational design of TaS 2 devices is hindered by a poor understanding of the switching mechanism, the pulse-induced phase, and the influence of material defects. Here, we operate a 2-terminal TaS 2 device within a scanning transmission electron microscope at cryogenic temperature, and directly visualize the changing charge density wave structure with nanoscale spatial resolution and down to 300 μs temporal resolution. We show that the pulse-induced transition is driven by Joule heating, and that the pulse-induced state corresponds to the nearly commensurate and incommensurate charge density wave phases, depending on the applied voltage amplitude. With our in operando cryogenic electron microscopy experiments, we directly correlate the charge density wave structure with the device resistance, and show that dislocations significantly impact device performance. This work resolves fundamental questions of resistive switching in TaS 2 devices, critical for engineering reliable and scalable TaS 2 electronics.

36 MATERIALS SCIENCE↗
DOE OSTI2021

The updated ITPA global H-mode confinement database: description and analysis

The multi-machine ITPA Global H-mode Confinement Database has been upgraded with new data from JET with the ITER-like wall and ASDEX Upgrade with the full tungsten wall. This paper describes the new database and presents results of regression analysis to estimate the global energy confinement scaling in H-mode plasmas using a standard power law. Various subsets of the database are considered, focusing on type of wall and divertor materials, confinement regime (all H-modes, ELMy H or ELM-free) and ITER-like constraints. Apart from ordinary least squares, two other, robust regression techniques are applied, which take into account uncertainty on all variables. Regression on data from individual devices shows that, generally, the confinement dependence on density and the power degradation are weakest in the fully metallic devices. Using the multi-machine scalings, predictions are made of the confinement time in a standard ELMy H-mode scenario in ITER. The uncertainty on the scaling parameters is discussed with a view to practically useful error bars on the parameters and predictions. One of the derived scalings for ELMy H-modes on an ITER-like subset is studied in particular and compared to the IPB98(y,2) confinement scaling in engineering and dimensionless form. Transformation of this new scaling from engineering variables to dimensionless quantities is shown to result in large error bars on the dimensionless scaling. Regression analysis in the space of dimensionless variables is therefore proposed as an alternative, yielding acceptable estimates for the dimensionless scaling. The new scaling, which is dimensionally correct within the uncertainties, suggests that some dependencies of confinement in the multi- machine database can be reconciled with parameter scans in individual devices. This includes vanishingly small dependence of confinement on line-averaged density and normalized plasma pressure (β), as well as a noticeable, positive dependence on effective atomic mass and plasma triangularity. Extrapolation of this scaling to ITER yields a somewhat lower confinement time compared to the IPB98(y, 2) prediction, possibly related to the considerably weaker dependence on major radius in the new scaling (slightly above linear). Further studies are needed to compare more flexible regression models with the power law used here. In addition, data from more devices concerning possible ‘hidden variables’ could help to determine their influence on confinement, while adding data in sparsely populated areas of the parameter space may contribute to further disentangling some of the global confinement dependencies in tokamak plasmas.

Database↗
DOE OSTI2021

Solvation of NiO x for hole transport layer deposition in perovskite solar cells

In this work, a series of nickel oxide (NiO x ) inks, in the perovskite antisolvent chlorobenzene (CB) containing 15% ethanol, were prepared for the fabrication of p-i-n perovskite solar cells by blade coating. The inks included triethylamine (Et 3 N) and alkyl xanthate salts as ligands to disperse NiO x particle aggregates and stabilize suspension. A total of four inks were evaluated: 0X (Et 3 N with no alkyl xanthate), 4X (Et 3 N + potassium n-butyl xanthate), 12X (Et 3 N + potassium n-dodecyl xanthate), and 18X (Et 3 N + potassium n-octadecyl xanthate). The inks were characterized by UV-visible spectroscopy and FT-IR spectroscopy and the resulting films analyzed by thermogravimetry and scanning electron microscopy. Devices prepared using the 0X ink resulted in a peak power conversion efficiency (PCE) of 14.47% (0.25 cm 2 ) and 9.96 % (1 cm 2 ). The 0X devices showed no significant loss of PCE after 100 days in a nitrogen flow box. Devices prepared with inks containing alkyl xanthate ligand had lower PCE that decreased with decreasing chain length, 18X > 12X > 4X.

14 SOLAR ENERGY↗
DOE OSTI2021

Results from Accelerated Environmental Testing of Barcoded Identifiers for UF 6 Cylinders

This report provides the qualitative and quantitative results from the accelerated environmental testing campaign. A total of 444 samples were subjected to 10 tests that included UV, salt fog, temperature, blowing dust, high pressure and temperature water, and impact exposure. Each sample included a two-dimensional barcode and an alphanumeric string representing the cylinder identification number. When evaluating the results, primary attention was placed on the decodability of the barcodes using a barcode verifier device, since machine scanning a barcode offers the greatest efficiency and accuracy gains when reading cylinder identification numbers during safeguards activities. Contrast was considered the critical test parameter because maintaining contrast under a wide range of environmental conditions is of fundamental importance to decoding the identification number of the barcodes. Additionally, manual readability of the alphanumeric string was considered an important factor in determining whether an inspector or operator could still read the identification number of the cylinder if the barcode proved to be undecodable.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

Local imaging of diamagnetism in proximity-coupled niobium nanoisland arrays on gold thin films.

In this work, we study the effect of engineered disorder on the local magnetic response of proximity-coupled superconducting island arrays by comparing scanning superconducting quantum interference device (SQUID) susceptibility measurements to a model in which we treat the system as a network of one-dimensional (1D) superconductor-normal-metal-superconductor Josephson junctions, each with a Josephson coupling energy E-J determined by the junction length or distance between islands. We find that the disordered arrays exhibit a spatially inhomogeneous diamagnetic response which, for low local applied magnetic fields, is well described by this junction network model, and we discuss these results as they relate to inhomogeneous 2D superconductors. Our model of the static magnetic response of the arrays does not fully capture the onset of nonlinearity and dissipation with increasing applied field, as these effects are associated with vortex motion due to the dynamic nature of the scanning SQUID susceptometry measurement. This work demonstrates a model 2D superconducting system with engineered disorder, and it highlights the impact of dissipation on the local magnetic properties of 2D superconductors and Josephson junction arrays.

Bishop-Van Horn, Logan↗
DOE OSTI2019

Infections in patients using ventricular-assist devices: Comparison of the diagnostic performance of {sup 18}F-FDG PET/CT scan and leucocyte-labeled scintigraphy

Background: The usage of left-ventricular-assist device (LVAD) is increasing in patients presenting with advanced heart failure. However, device-related infections are a challenge to recognize and to treat, with an important morbidity and mortality rate. The role of nuclear medicine imaging remains not well established for LVAD infections. The present study compared the accuracy of positron emission tomography/computed tomography with {sup 18}F-fludeoxyglucose ({sup 18}F-FDG PET/CT) and radiolabeled leucocyte scintigraphy for the diagnosis of infections in patients supported with a continuous-flow LVAD. Methods: From a prospectively maintained database, we retrospectively analyzed the diagnostic performance of radiolabeled leucocyte scintigraphy and {sup 18}F-FDG PET/CT in 24 patients who had a LVAD with a suspected device-related infection. Both examinations were routinely performed in all patients. Infection was assessed by the International Society for Heart and Lung Transplantation criteria. Results: Twenty-four patients were included: 15 had a specific VAD infection (5 cardiac-LVAD and 10 driveline), 6 had a VAD-related infection, while 3 patients had a non-VAD-related infection. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 95.2%, 66.7%, 95.2%, 66.7%, and 91.6%, respectively, for {sup 18}F-FDG-PET; and 71.4%, 100%, 100%, 33.3%, and 75%, respectively, for leucocyte scintigraphy. {sup 18}F-FDG PET/CT showed significantly higher sensitivity (P = 0.01) than leucocyte scintigraphy. Conclusion: {sup 18}F-FDG PET/CT and radiolabeled leucocyte scintigraphy single-photon emission computed tomography carry high performance in the diagnostic of LVAD infections. {sup 18}F-FDG PET/CT shows significantly higher sensitivity and could be proposed as first-line nuclear medicine procedure. [French] French Abstract: Contexte: L’utilisation du dispositif d’assistance ventriculaire gauche (DAVG) est en utilisation croissante chez les patients avec insuffisance cardiaque avancée. Cependant, les infections liées au dispositif sont un défi à reconnaître et à traiter en raison d’ un taux de morbidité et de mortalité important. Le rôle de l’imagerie de médecine nucléaire n’est pas encore bien établi pour les infections secondaires au DAVG. La présente étude compare la précision de la tomographie par émission de positrons / tomodensitométrie au 18F-fluorodéoxyglucose (18F-FDG TEP/TDM) et la scintigraphie leucocytaire radio-marquée pour le diagnostic d’infections chez des patients porteurs par un DAVG à flux continu. Méthodes: A partir d’une base de données complétée de manière prospective nous avons analysé rétrospectivement les performances diagnostiques de la scintigraphie leucocytaire radio-marquée et de la TEP / TDM au 18F-FDG chez 24 patients ayant un DAVG avec une infection suspectée liée à l’appareillage. Les deux types d’examens scintigraphiques ont été systématiquement réalisé chez tous les patients. Le diagnostic d’infection fut établi selon les critères ISHLT. Résultats: Parmi les 24 patients inclus, 15 avaient une infection spécifique de l’appareillage AVG (5 au niveau de la pompe et/ou canule d’insertion myocardique) et 10 au niveau du driveline, 6 avaient une infection indirectement liée à l’appareillage AVG, tandis que 3 patients avaient une infection non liée au DAVG. La sensibilité, la spécificité, la valeur prédictive positive, la valeur prédictive négative et la précision étaient de 95,2%, 66,7%, 95,2%, 66,7% et 91,6%, respectivement, pour le 18F-FDG-PET et 71,4%, 100%, 100%, 33,3 %, et 75%, respectivement, pour la scintigraphie leucocytaire. La TEP / TDM au 18F-FDG a montré une sensitivité significativement plus élevée (p = 0,01) que la scintigraphie leucocytaire. Conclusion: 18F-FDG TEP/TDM et scintigraphie leucocytaire radio-marquée SPECT s’avèrent très efficaces pour le diagnostic des infections à DVAG. La TEP/TDM au 18F-FDG montre une sensibilité significativement plus élevée et pourrait être proposée en tant que la procédure de médecine nucléaire de premier choix. [Spanish] Spanish Abstract: Antecedentes: El uso de dispositivos de asistencia ventricular izquierda (DAVI) está incrementando en pacientes con insuficiencia cardiaca avanzada. Sin embargo, las infecciones relacionadas al dispositivo representan un reto diagnóstico y de tratamiento, con una importante tasa de morbilidad y mortalidad. El papel de los estudios de imagen de medicina nuclear en las infecciones de DAVI no se ha establecido claramente. El presente estudio comparó la precisión de la tomografía por emisión de positrones/tomografía computada con {sup 18}F-fluorodesoxiglucosa ({sup 18}F-FDG PET/CT) y la gammagrafía con leucocitos marcados para el diagnóstico de infecciones en pacientes utilizando un DAVI de flujo continuo. Métodos: Desde una base de datos obtenida de manera prospectiva, analizamos de manera retrospectiva el rendimiento diagnóstico de la gammagrafía de leucocitos marcados y del {sup 18}F-FDG PET/CT en 24 pacientes quienes tenían un DAVI con sospecha de infección relacionada al dispositivo. Ambos estudios fueron realizados rutinariamente en todos los pacientes. Se determinó la presencia de infección mediante los criterios de la ISHTL. Resultados: Se incluyeron veinticuatro pacientes, de los cuales 15 tuvieron una infección específica de DAV (5 con infecciones DAVI, y 10 con infección del driveline), 6 tuvieron una infección relacionada al DAV, y 3 pacientes tuvieron una infección no relacionada al DAV. La sensibilidad, especificidad, valor predictivo positivo, valor predictivo negativo y precisión diagnóstica fueron 95.2%, 66.7%, 95.2%, 66.7% y 91.6%, respectivamente para {sup 18}F-FDG PET/CT, y 71.4%, 100%, 100%, 33.3% y 75%, respectivamente para la gammagrafía de leucocitos marcados. El {sup 18}F-FDG PET/CT mostró una significativa mayor sensibilidad (p=0.01) que la gammagrafía con leucocitos marcados. Conclusión: El {sup 18}F-FDG PET/CT y la gammagrafía de leucocitos marcados tienen un alto desempeño en el diagnóstico de infecciones de DAVI. El {sup 18}F-FDG PET/CT muestra una significativa mayor sensibilidad y podría ser propuesto como el procedimiento de medicina nuclear de primera línea. [Chinese] Chinese Abstract: 背景: 左心室辅助装置 (LVAD) 越来越多的应用于重度心力衰竭患者。然而, 设备相关的感染有着重要的发病率和死亡率, 并且对其诊断和治疗均是一项挑战。对于 LVAD 相关感染, 核医学影像可扮演的角色一直没有完善。本研究针对装备有连续流式 LVAD 的感染病人,对比了 {sup 18}F-FDG PET/CT 造影术和放射性标记白细胞闪烁扫描法对感染诊断的准确性。 方法: 从一个前瞻性的数据库, 入选了24名疑似设备感染的 LVAD 病人, 并回顾性的分析了放射性标记白细胞闪烁扫描法和 {sup 18}F-FDG PET/CT 的诊断表现。所有病人都常规进行了上述两种检查。利用 ISHLT 标准对感染情况进行评估。 结果: 在入选的 24 名病人中, 15 名有明确的 VAD 感染 (5 名心脏的 LVAD 和 10 名动力传动系统装置), 6 名有 VAD 相关的感染,另外3名有 VAD 无关的感染。对于 {sup 18}F-FDG PET/CT 诊断方法,其敏感性,特异性,阳性预测值,阴性预测值和准确率分别为: 95.2%, 66.7%, 95.2%, 66.7%, 和 91.6%; 而对于白细胞闪烁扫描诊断方法, 其敏感性, 特异性, 阳性预测值,阴性预测值和准确率分别为: 71.4%, 100%, 100%, 33.3% 和 75%。相比于白细胞闪烁扫描, {sup 18}F-FDG PET/CT 明显展现出较高的敏感性 (p=0.01)。 结论: {sup 18}F-FDG PET/CT 和白细胞闪烁扫描 SPECT 对于 LVAD 感染的诊断具有很好的表现。{sup 18}F-FDG PET/CT 展现出较高的敏感性,可以作为核医学的首要检查。.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

Microscopy of hydrogen and hydrogen-vacancy defect structures on graphene devices

Here, we have used scanning tunneling microscopy (STM) to investigate two types of hydrogen defect structures on monolayer graphene supported by hexagonal boron nitride (h-BN) in a gated field-effect transistor configuration. The first H-defect type is created by bombarding graphene with 1-keV ionized hydrogen and is identified as two hydrogen atoms bonded to a graphene vacancy via comparison of experimental data to first-principles calculations. The second type of H defect is identified as dimerized hydrogen and is created by depositing atomic hydrogen having only thermal energy onto a graphene surface. Scanning tunneling spectroscopy (STS) measurements reveal that hydrogen dimers formed in this way open a new elastic channel in the tunneling conductance between an STM tip and graphene.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗