Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “device”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,333 records · Page 74
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Laser machined plastic laminates. Towards portable diagnostic devices for use in low resource environments

Despite significant progress in development of bioanalytical devices cost, complexity, access to reagents and lack of infrastructure have prevented use of these technologies in resource-limited regions. To provide a sustainable tool in the global effort to combat infectious diseases the diagnostic device must be low cost, simple to operate and read, robust, and have sensitivity and specificity comparable to laboratory analysis. Thus, in this mini-review we describe recent work using laser machined plastic laminates to produce diagnostic devices that are capable of a wide variety of bioanalytical measurements and show great promise towards future use in low-resource environments.

47 OTHER INSTRUMENTATION↗
DOE OSTI2020

Temperature dependence of nickel ion release from nitinol medical devices

Abstract Nitinol exhibits unique (thermo)mechanical properties that make it central to the design of many medical devices. However, nitinol nominally contains 50 atomic percent nickel, which if released in sufficient quantities, can lead to adverse health effects. While nickel release from nitinol devices is typically characterized using in vitro immersion tests, these evaluations require lengthy time periods. We have explored elevated temperature as a potential method to expedite this testing. Nickel release was characterized in nitinol materials with surface oxide thickness ranging from 12 to 1564 nm at four different temperatures from 310 to 360 K. We found that for three of the materials with relatively thin oxide layers, ≤ 87 nm nickel release exhibited Arrhenius behavior over the entire temperature range with activation energies of 80 to 85 kJ/mol. Conversely, the fourth ''black–oxide'' material, with a much thicker, complex oxide layer, was not well characterized by an Arrhenius relationship. Power law release profiles were observed in all four materials; however, the exponent from the thin oxide materials was approximately 1/4 compared with 3/4 for the black–oxide material. To illustrate the potential benefit of using elevated temperature to abbreviate nickel release testing, we demonstrated that a > 50 day 310 K release profile could be accurately recovered by testing for less than 1 week at 340 K. However, because the materials explored in this study were limited, additional testing and mechanistic insight are needed to establish a protective temperature scaling that can be applied to all nitinol medical device components.

Saylor, David M.↗
DOE OSTI2019

Characterization and modeling of reverse-bias breakdown in Cu(In,Ga)Se 2 photovoltaic devices

Partial shading of series-connected thin-film photovoltaic modules can force shaded cells into reverse bias, which can cause rapid and irreversible power loss and reduce the practical module lifespan. Unfortunately, this is a common occurrence in field-deployed modules due to the myriad of environmental factors that can result in partial shading. In this work, we identify as-grown nonuniformities in the Cu(In,Ga)Se 2 (CIGS) absorber layers as the points of origin for the damage induced under reverse-bias conditions. The structure and chemistry associated with inclusions and voids in the CIGS films cause these features to act as resistive heating elements in reverse-bias conditions. This localized resistive heating provides the energy required to induce thermal runaway breakdown in the CIGS devices, resulting in damage to charge collection and reduced active area of a device. This mechanism is also described with a robust device model to connect the experimental observations with their physical origins.

14 SOLAR ENERGY↗
DOE OSTI2025

Autonomous Aerosol and Plasma Co‐Jet Printing of Metallic Devices at Ambient Temperature

Abstract Additive manufacturing of metallic materials holds the potential to revolutionize the fabrication of functional devices unattainable via traditional methods. Despite recent advancements, printing metallic materials typically requires thermal processing at elevated temperatures to form dense structures with desired properties, which presents a major challenge for direct printing and integration with temperature‐sensitive materials. Herein, a unique co‐jet printing (CJP) method is reported integrating an aerosol jet and a non‐thermal, atmospheric pressure plasma jet to enable concurrent aerosol deposition of metal nanoparticle inks and in situ sintering at ambient temperature. A machine learning algorithm is integrated with the CJP to perform real‐time defect detection and autonomous correction, enhancing the yield of printed films with high electrical conductivity from 44% to 94%. Concurrent printing and sintering eliminate the need for post‐printing processing, reducing the overall manufacturing time by multiple folds depending on product size. CJP enables direct printing of functional devices on a variety of temperature‐sensitive materials including biological materials. Direct printing of hydration sensors on living plant leaves is demonstrated for long‐duration monitoring of hydration level in the plant. The versatile CJP method opens tremendous opportunities to harmoniously integrate abiotic and biotic materials for emerging applications in wearable/implantable devices and biohybrid systems.

Du, Yipu [Department of Aerospace and Mechanical E↗
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 OSTI2019

Catheter-Directed Fenestration for Branch Vessel Reconnection in Aortic Dissection Using a Novel Diamond-Tipped Chronic Total Occlusion Drilling Device: A Technical Report

Purpose: Aortic dissection is a complex condition with high morbidity and mortality. Endovascular treatments including percutaneous fenestration can be used to manage branch vessel ischaemia or risk of aortic rupture. A variety of techniques for aortic fenestration have been described. We describe the novel use of the TruePath Chronic Total Occlusion (CTO) device for aortic intimal fenestration to achieve side branch reconnection. Materials and Methods: We present three cases of aortic dissection presenting with symptoms of aortic side branch occlusion and end organ malperfusion, treated with aortic fenestration using the TruePath CTO device via trans-brachial and trans-femoral approaches. Results: Technical success was achieved in all three cases. No complications were encountered. Flow was restored in compromised visceral branches. Branches remained patent on follow-up CT angiography over a minimum 2.5-year follow-up period. Conclusion: Percutaneous aortic fenestration techniques enable a minimally invasive approach to treat visceral branch malperfusion associated with aortic dissection. The TruePath CTO device improves the control of the fenestration procedure with the potential to improve efficacy and safety.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Transseptal Puncture: Devices, Techniques, and Considerations for Specific Interventions

Purpose of Review: Transseptal puncture is a routinely performed interventional cardiology procedure for an array of cardiac diseases. We aimed to review the current status of available devices and techniques of transseptal puncture with consideration to specific interventions. Recent Findings: Except for a few modifications, devices for transseptal puncture technique has not changed much compared to when it was first described almost 60 years ago. For difficult transseptal puncture, a few newer techniques such as radio frequency needle puncture system have been used but there is lack of robust clinical study. Advanced imaging, such as intracardiac echocardiography and transesophageal echocardiography, has been found to make transseptal puncture safer. A new transseptal approach that incorporates 3D non-fluoroscopic catheter tracking systems has shown promising results in two human studies. Summary: While various modifications in the transseptal technique tailored to the specific interventions have improved procedural safety, further improvement in existing devices focusing on distinct procedure might be needed in the future.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
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 OSTI2017

Flow and Turbulence Control in a Boundary Layer Wind Tunnel Using Passive Hardware Devices

The Climatic Wind Tunnel (CWT) is a new experimental facility of the Institute of Theoretical and Applied Mechanics (ITAM) in Prague, Czech Republic. It is uniquely able to replicate precipitation and freezing effects on structural models in the climatic test section, and simultaneously perform aerodynamic and aeroelastic tests on structural models in the aerodynamic test section. Extensive measurements are carried out to investigate airflow and turbulence characteristics in the empty aerodynamic test section. Capability to experimentally simulate the atmospheric boundary layer (ABL) is studied using castellated barrier wall, Counihan vortex generators, and surface roughness elements. An individual influence of each of these passive hardware devices is separately tested as well, as they are commonly used combined, and their individual contributions to the ABL model characteristics are not well known. The analysis is based on hot-wire anemometer measurements carried out at various cross sections in the aerodynamic test section of the CWT. Experimental results are reported as mean velocity and turbulence intensity fields for the empty aerodynamic test section without passive hardware devices. Vertical profiles of mean velocity, turbulence intensity, and turbulence length scales, as well as power spectral density of velocity fluctuations, are reported for the ABL small-scale model. The barrier is observed to cause a decrease in flow velocity and an increase in turbulence close to surface. Vortex generators enhance turbulence throughout the entire height range under scope. Increased turbulence and decreased flow velocity are particularly exhibited close to surface due to surface roughness. Influence of each of the studied passive hardware devices on flow and turbulence is quantified in a dimensionless form to allow for separately accounting for their effects.

42 ENGINEERING↗
DOE OSTI2024

Interpenetrated Structures for Enhancing Ion Diffusion Kinetics in Electrochemical Energy Storage Devices

The architectural design of electrodes offers new opportunities for next-generation electrochemical energy storage devices (EESDs) by increasing surface area, thickness, and active materials mass loading while maintaining good ion diffusion through optimized electrode tortuosity. However, conventional thick electrodes increase ion diffusion length and cause larger ion concentration gradients, limiting reaction kinetics. We demonstrate a strategy for building interpenetrated structures that shortens ion diffusion length and reduces ion concentration inhomogeneity. This free-standing device structure also avoids short-circuiting without needing a separator. The feature size and number of interpenetrated units can be adjusted during printing to balance surface area and ion diffusion. Starting with a 3D-printed interpenetrated polymer substrate, we metallize it to make it conductive. This substrate has two individually addressable electrodes, allowing selective electrodeposition of energy storage materials. Using a Zn//MnO 2 battery as a model system, the interpenetrated device outperforms conventional separate electrode configurations, improving volumetric energy density by 221% and exhibiting a higher capacity retention rate of 49% compared to 35% at temperatures from 20 to 0 °C. Our study introduces a new EESD architecture applicable to Li-ion, Na-ion batteries, supercapacitors, etc.

25 ENERGY STORAGE↗
DOE OSTI2017

High power beta electron device - Beyond betavoltaics

Developing watt level power sources with beta emitting radioisotopes has been limited by the inability to utilize high energy (> 100 KeV) beta emitters at high radioisotope loadings without damaging the energy conversion materials. A new type of beta electron power source is described that removes those restrictions. This approach contains the radioisotope in a beta transparent titanium tube and confines beta electrons emitted through the tube wall to spiral trajectories around the tube with an axial magnetic field. The confined beta electrons dissipate energy though multiple interactions with surrounding excimer precursor gas atoms to efficiently generate photons. Photovoltaic cells convert the photons to electrical power. Since the beta electrons dissipate energy in the excimer precursor gas, the device can be loaded with more than 10 13 Bq of radioisotope to generate 100 milliwatt to watt levels of electrical power without damaging the device materials or degrading its performance. Furthermore, the power source can use a variety of beta radioisotopes and scales by stacking the devices.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2019

Effect of rapid thermal annealing of copper indium aluminium gallium diselenide solar cell devices and its deposition challenges

Thin-film photovoltaic research based on ternary or quaternary absorber materials has mainly concentrated on copper (indium/gallium) diselenide, CuIn x Ga 1-x Se 2 (CIGS). This material has demonstrated exceptional energy conversion efficiencies. By altering the In/Ga ratio the band gap can be varied from 1.02 eV (for CuInSe 2 ) to 1.68 eV (for CuGaSe 2 ). However, research from leading groups showed that cells have maximum efficiency at or below 1.35 eV. This paper reports the challenges of using aluminium alloyed CIGS deposited with a single step co-evaporation method. Adding aluminium is found to reduce the bulk trap state density for wide gap devices. However, it created significant safety issues when compared to conventional CIGS co-evaporation deposition systems. The release of H 2 Se when moisture comes in contact with aluminium selenide was resolved by placing exhaust lines at various places of the deposition chamber. A single phase CIAGS device with a bandgap of 1.30 eV was prepared using a co-evaporation method. The fabricated solar cell devices with CIAGS absorber layers and resulted in a photoconversion efficiency of 10.3%. A progressive rapid thermal annealing at various temperature resulted in a 10% increase in the overall efficiency at 300 °C. The efficiencies were reduced when the RTA temperature increased above 300 °C.

14 SOLAR ENERGY↗
DOE OSTI2021

SIMS and HR-XPS characterization of lithiated graphite from the magnetic fusion device RFX-mod

Lithium wall conditioning has improved the performance of many magnetic fusion devices. Li conditioning in the RFX-mod device was performed by: (1) a single Li pellet injector and (2) a multi-Li pellet injector during He plasma discharges; (3) a Li evaporator after He glow discharge cleaning and He plasma discharge exposure. This report compares the spatial and depth distributions of Li deposited on polycrystalline graphite witness samples at different locations in RFX-mod and the elemental and chemical compositions of the resulting surfaces. The sample surfaces were analyzed ex situ using secondary ion mass spectrometry (SIMS) and high-resolution X-ray photoelectron spectroscopy (HR-XPS). The results showed that Li pellet injection provided a relatively uniform toroidal coverage while Li evaporation produced highly localized Li deposition. A Li 1s HR-XPS peak at 56.5 eV binding energy (BE) characteristic of lithium-intercalated graphite was only observed with the sample exposed to Li evaporation. All of the samples exhibited a HR-XPS C 1s peak at 285.1–285.2 eV BE that is largely attributed to hydrogenated graphite. This finding suggests that hydrogenation of fresh graphite occurs during He plasma discharge exposures. Finally, our results have implications for density control and the selection of Li conditioning techniques in magnetic fusion devices.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2013

Magnetic Fe3O4@TiO2 Nanoparticles-based Test Strip Immunosensing Device for Rapid Detection of Phosphorylated Butyrylcholinesterase

An integrated magnetic nanoparticles-based test-strip immunosensing device was developed for rapid and sensitive quantification of phosphorylated butyrylcholinesterase (BChE), the biomarker of exposure to organophosphous pesticides (OP), in human plasma. In order to overcome the difficulty in scarce availability of OP-specific antibody, here magnetic Fe3O4@TiO2 nanoparticles were used and adsorbed on the test strip through a small magnet inserted in the device to capture target OP-BChE through selective binding between TiO2 and OP moiety. Further recognition was completed by horseradish peroxidase (HRP) and anti-BChE antibody (Ab) co-immobilized gold nanoparticles (GNPs). Their strong affinities among Fe3O4@TiO2, OP-BChE and HRP/Ab-GNPs were characterized by quartz crystal microbalance (QCM), surface plasmon resonance (SPR) and square wave voltammetry (SWV) measurements. After cutting off from test strip, the resulted immunocomplex (HRP/Ab-GNPs/OP-BChE/Fe3O4@TiO2) was measured by SWV using a screen printed electrode under the test zone. Greatly enhanced sensitivity was achieved by introduction of GNPs to link enzyme and antibody at high ratio, which amplifies electrocatalytic signal significantly. Moreover, the use of test strip for fast immunoreactions reduces analytical time remarkably. Coupling with a portable electrochemical detector, the integrated device with advanced nanotechnology displays great promise for sensitive, rapid and in-filed on-site evaluation of OP poisoning.

biomarkers↗
DOE OSTI2022

Spatial influence of paramagnetic molecules on magnetic tunnel junction-based molecular spintronic devices (MTJMSD)

Magnetic Tunnel Junction-Based Molecular Spintronic Devices (MTJMSDs) are potential candidates for inventing highly correlated systems. Understanding MTJMSD's magnetic behavior is essential to designing and fabricating practical devices. This paper investigates the effect of two contributing factors on MTJMSD's magnetic properties via Monte Carlo Simulation. Here, we have systematically studied coupling strengths and nature between magnetic molecules and ferromagnetic electrodes at various temperatures. We have also investigated the effect of length and thickness increase on MTJMSD temporal and spatial evolution of magnetic moment, magnetic correlation, and magnetic susceptibility. Our results showed that thermal energy increase significantly affects molecular devices.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2014

Perfectly Matched Layers versus discrete transparent boundary conditions in quantum device simulations

Discrete transparent boundary conditions (DTBC) and the Perfectly Matched Layers (PML) method for the realization of open boundary conditions in quantum device simulations are compared, based on the stationary and time-dependent Schrödinger equation. The comparison includes scattering state, wave packet, and transient scattering state simulations in one and two space dimensions. The Schrödinger equation is discretized by a second-order Crank–Nicolson method in case of DTBC. For the discretization with PML, symmetric second-, fourth-, and sixth-order spatial approximations as well as Crank–Nicolson and classical Runge–Kutta time-integration methods are employed. In two space dimensions, a ring-shaped quantum waveguide device is simulated in the stationary and transient regime. As an application, a simulation of the Aharonov–Bohm effect in this device is performed, showing the excitation of bound states localized in the ring region. The numerical experiments show that the results obtained from PML are comparable to those obtained using DTBC, while keeping the high numerical efficiency and flexibility as well as the ease of implementation of the former method. -- Highlights: •In-depth comparison between discrete transparent boundary conditions (DTBC) and PML. •First 2-D transient scattering state simulations using DTBC. •First 2-D transient scattering state simulations of the Aharonov–Bohm effect.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

Efficient and scalable GaInAs thermophotovoltaic devices

We report thermophotovoltaics are promising solid-state energy converters for a variety of applications such as grid-scale energy storage, concentrating solar-thermal power, and waste-heat recovery. Here, we report the design, fabrication, and testing of large area (0.8 cm 2 ), scalable, single-junction 0.75-eV GaInAs thermophotovoltaic devices reaching an efficiency of 38.8% +/- 2.0% and an electrical power density of 3.78 W/cm 2 at an emitter temperature of 1,850 °C. Reaching such a high emitter temperature and power density without sacrificing efficiency is a direct result of combining good spectral management with an optimized cell architecture, excellent material quality, and low series resistance. Importantly, fabrication of 12 high-performing devices on a 2-in wafer is shown to be repeatable, and the cell design can be readily transferred to commercial epitaxy on even larger wafers. Further improvements in efficiency can be obtained by using a multijunction architecture, illustrated by early results for a two-junction 0.84-eV GaInPAs/0.75-eV GaInAs device.

14 SOLAR ENERGY↗
DOE OSTI2018

Comparative SEM and TEM analyses of apatite phases prepared by a multi-sample loading device

Highlights: • A multi-sample loading device which ultrasonically disperses samples was developed. • Comparative EM analyses on various apatite phases were efficiently carried out. • SEM-EDS data revealed distinctive values of O/P and Ca/P intensity ratios. • TEM-SAED data presented characteristic structural features of apatite phases. • Lattice parameters of bone and fossil apatite were affected by CO{sub 3} content. - Abstract: Comparative chemical and structural characterization of various apatite phases from both synthetic and natural sources were carried out by utilizing a multi-sample loading device developed for scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses. The device is capable of spraying nanoparticles via ultrasonication, and four separate samples were loaded on a single TEM grid by a masking tool to characterize different apatite phases in consistent instrumental and analytical conditions. SEM energy dispersive spectroscopy (EDS) analysis of the apatite samples revealed distinctive values of O/P and Ca/P intensity ratios except for the fossil apatite due to its high proportion of externally originating phases. Selected area electron diffraction (SAED) pattern analysis presented the characteristic lattice parameters of the apatite phases, especially the bone and fossil apatite which had CO{sub 3}in their chemistry. Analyzing distinctive chemical and structural features among varied apatite phases can be efficiently carried out through electron microscopy with multiple samples on a single TEM grid, and such methods can be employed for characterizing a wider range of materials.

36 MATERIALS SCIENCE↗