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All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Grid Resiliency with a 100% Renewable Microgrid

San Diego Gas & Electric Company (SDG&E) installed America’s first and largest utility-scale microgrid in Borrego Springs in 2013. The first generation Borrego Springs Microgrid utilized diesel generators to form and stabilize the microgrid island, with support from grid-scale batteries and local solar photovoltaic (PV) generation. In this project, SDG&E in partnership with National Renewable Energy Laboratory (NREL) demonstrated through modeling, simulation and utility field testing that blackstart and islanding of the microgrid can be led with 100% renewable, inverter based resources (IBRs), to help reduce community reliance on conventional generation resources. Through equipment upgrades, grid-forming island leader capability was transitioned to a battery IBR instead of the Borrego Springs Microgrid diesel generators. A new microgrid controller was integrated to the microgrid and programmed to control and manage multiple energy storage systems. Synchrophasor and other power quality data verified autonomous, high-speed response of the IBRs through blackstart, islanding, and load step testing. Results of project field evaluations provide distribution systems operators (DSO) with increased confidence that renewable, IBR can replace traditional generators to blackstart and island microgrids and rapidly establish stable island frequency with rapid changes in peak power demand. Importantly, the project validated the integration feasibility of a distributed energy resource management system (DERMS) controller that manages multiple grid-forming and grid-following IBRs, establishing a standard design interface to reduce the complexity of integrating new DERs in the future and supporting replication by the industry. As a result of learnings in this project, SDG&E has implemented the microgrid controller strategy at multiple other microgrid sites, thereby validating the replicability of the solution. Hardware-in-the-loop (HIL) simulations including power and controller HIL hardware — along with electromagnetic transient (EMT) simulations of Borrego Springs Microgrid —informed adjustments to inverter parameters and were important to characterize the performance of the IBRs in relevant operating conditions before deployment. The EMT and HIL simulations of islanding the entire community are important contributions in providing confidence in IBR performance prior to future islanding of the community in the field. High-fidelity EMT and/or HIL simulation of IBRs can de-risk field operations, and its relevance and importance as a tool is increasing as distribution grids and microgrids become more complex and dynamic with an increasing proportion of renewable generation, distributed energy storage, and two-way power and energy flows.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2015

Tremor–genic slow slip regions may be deeper and warmer and may slip slower than non–tremor–genic regions

The slow slip events (SSEs) are observed worldwide and often coincide with tectonic tremor. Notable examples of SSEs lacking observed tectonic tremor, however, occur beneath Kilauea Volcano, Hawaii, the Boso Peninsula, Japan, {near San Juan Bautista on the San Andreas Fault, California, and recently in Central Ecuador. These SSEs are similar to other worldwide SSEs in many ways (e.g., size or duration), but lack the concurrent tectonic tremor observed elsewhere; instead they trigger swarms of regular earthquakes. We investigate the physical conditions that may distinguish these non-tremor-genic SSEs from those associated with tectonic tremor including: slip velocity, pressure, temperature, fluids and fault asperities, although we cannot eliminate the possibility that tectonic tremor may be obscured in highly attenuating regions. Slip velocities of SSEs at Kilauea Volcano (~10⁻⁶ m/s) and Boso Peninsula (~10⁻⁷ m/s) are among the fastest SSEs worldwide. Kilauea Volcano, the Boso Peninsula and Central Ecuador are also among the shallowest SSEs worldwide, and thus have lower confining pressures and cooler temperatures in their respective slow slip zones. {Fluids also likely contribute to tremor generation, and no corresponding zone of high v p /v s has been noted at Kilauea or Boso. We suggest that the relatively faster slip velocities at Kilauea Volcano and the Boso Peninsula result from specific physical conditions that may also be responsible for triggering swarms of regular earthquakes adjacent to the slow slip, while different conditions produce slower SSE velocities elsewhere and trigger tectonic tremor.

58 GEOSCIENCES↗
DOE OSTI2018

Coccidioidomycosis Dynamics in Relation to Climate in the Southwestern United States: Cocci. and climate in the SW U.S.

Valley fever is endemic to the southwestern United States. Humans contract this fungal disease by inhaling spores of Coccidioides spp. Changes in the environment can influence the abundance and dispersal of Coccidioides spp., causing fluctuations in valley fever incidence. We combined county-level case records from state health agencies to create a regional valley fever database for the southwestern United States, including Arizona, California, Nevada, New Mexico, and Utah. We used this data set to explore how environmental factors influenced the spatial pattern and temporal dynamics of valley fever incidence during 2000–2015. We compiled climate and environmental geospatial data sets from multiple sources to compare with valley fever incidence. These variables included air temperature, precipitation, soil moisture, surface dust concentration, normalized difference vegetation index, and cropland area. We found that valley fever incidence was greater in areas with warmer air temperatures and drier soils. The mean annual cycle of incidence varied throughout the southwestern United States and peaked following periods of low precipitation and soil moisture. From year-to-year, however, autumn incidence was higher following cooler, wetter, and productive springs in the San Joaquin Valley of California. In southcentral Arizona, incidence increased significantly through time. By 2015, incidence in this region was more than double the rate in the San Joaquin Valley. Our analysis provides a framework for interpreting the influence of climate change on valley fever incidence dynamics. Our results may allow the U.S. Centers for Disease Control and Prevention to improve their estimates of the spatial pattern and intensity of valley fever endemicity.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Insight into the Solid Electrolyte Interphase Formation in Bis(fluorosulfonyl)Imide Based Ionic Liquid Electrolytes

The formation of the solid electrolyte interphase (SEI) in an ionic liquid electrolyte of 0.5 m lithium bis(fluorosulfonyl)imide (LiFSI) in 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide at high cell voltages (1.7–1.9 V) is investigated in ordered mesoporous carbon (OMC) based Li metal cells using an operando small-angle neutron scattering (SANS) technique coupled with electrochemical impedance spectroscopy and ex situ X-ray photoelectron spectroscopy (XPS). It is demonstrated that discharging the OMC Li metal cells to ≈2 V and holding the cell voltage constant induces a rapid current increase with time, confirming extensive reduction and SEI formation. XPS analysis reveals that LiF is formed at open cell voltage (OCV), which is attributed to the carbenes generated at the lithium negative electrode because of its reaction with EMIm cation diffusing to and initiating the reaction with FSI - anions at the carbon positive electrode. It is confirmed that the chemical reaction at OCV and electrochemical reduction at high cell voltage of the FSI - anion plays a protective role against EMIm cation co-intercalation into the carbon positive electrode during the initial discharge. Operando SANS studies also suggest that slight differences occur in the surface composition and reaction mechanism as a function of cell voltage.

1-ethyl-3- methylimidazolium bis(fluorosulfonyl)im↗
DOE OSTI2022

Impacts of Bond Type and Grafting Density on the Thermal, Structural, and Transport Behaviors of Nanoparticle Organic Hybrid Materials–Based Electrolytes

Nanoscale Organic Hybrid Materials (NOHMs) consist of polymers tethered to a nanoparticle surface, and NOHMs formed with an ionic bond between the polymer and nanoparticle have been proposed for electrochemical applications. NOHMs exhibit negligible vapor pressure, chemical tunability, oxidative thermal stability, and high ionic conductivity making them attractive in reactive and separation systems. In this study, NOHMs are synthesized by tethering Jeffamine M2070 (HPE) to SiO 2 nanocores via ionic (NOHM-I-HPE) and covalent (NOHM-C-HPE) bonding to investigate the effect of the bond type on the thermal, structural and transport properties of the tethered HPE. In the neat state, NOHM-C-HPE displays the highest thermal stability in a nitrogen atmosphere, while NOHM-I-HPE is the most stable under oxidative conditions. Small-angle neutron scattering (SANS) reveals the presence of multiple types of HPE polymers in aqueous solutions of NOHM-I-HPE (i.e., tethered, interacting, and free), whereas only tethered HPE is observed in NOHM-C-HPE systems. Moreover, the SANS profiles identify clustering of NOHM-C-HPE in aqueous solutions, but not in the corresponding NOHM-I-HPE solutions, suggesting that the free HPE chains stabilize the dispersion of NOHM-I-HPE. Furthermore, the results of this study elucidate how the bond type and grafting density can be used to tune the properties of NOHMs.

25 ENERGY STORAGE↗
DOE OSTI2024

Underlying Roles of Polyol Additives in Promoting CO2 Capture in PEI/Silica Adsorbents

Solid-supported amines having low molecular weight branched poly(ethylenimine) (PEI) physically impregnated into porous solid supports are promising adsorbents for CO2 capture. Co-impregnating short-chain poly(ethylene glycol) (PEG) together with PEI alters the performance of the adsorbent, delivering improved amine efficiency (AE, mol CO2 sorbed / mol N) and faster CO2 uptake rates. To uncover the physical basis for this improved gas capture performance, we probed the distribution and mobility of the polymers in the pores via small angle neutron scattering (SANS), solid-state NMR, and molecular dynamic (MD) simulation studies. SANS and MD simulations reveal that PEG displaces wall-bound PEI, making amines more accessible for CO2 sorption. Solid-state NMR and MD simulation suggest intercalation of PEG into PEI domains, separating PEI domains and reducing amine-amine interactions, providing potential PEG-rich and amine-poor interfacial domains that bind CO2 weakly via physisorption while providing facile pathways for CO2 diffusion. Contrary to a prior literature hypothesis, no evidence is obtained for PEG facilitating PEI mobility in solid supports. Instead, the data suggest that PEG chains coordinate to PEI, form larger bodies with reduced mobility compared to PEI alone. We also demonstrate promising CO2 uptake and desorption kinetics at varied temperatures, given by favorable amine distribution.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2011

Health, safety, and environmental risks from energy production: A year-long reality check

Large-scale carbon dioxide capture and storage (CCS) offers the benefit of reducing CO{sub 2} emissions and thereby mitigating climate change risk, but it will also bring its own health, safety, and environmental risks. Curtis M. Oldenburg, Editor-in-Chief, considers these risks in the context of the broader picture of energy production. Over the last year, there have been major acute health, safety, and environmental (HSE) consequences related to accidents involving energy production from every major primary energy source. These are, in chronological order: (i) the Upper Big Branch (coal) Mine disaster, (ii) the Gulf of Mexico Macondo (oil) well blowout, (iii) the San Bruno (natural gas) pipeline leak and explosion, and (iv) the Fukushima (nuclear) reactor radioactivity releases. Briefly, the Upper Big Branch Mine disaster occurred in West Virginia on April 5, 2010, when natural methane in the mine ignited, causing the deaths of 29 miners, the worst coal mine disaster in the USA since 1970. Fifteen days later, the Macondo oil well in the Gulf of Mexico suffered a blowout, with a gas explosion and fire on the floating drilling platform that killed 11 people. The oil and gas continued to flow out of the well at the seafloor until July 15, 2010, spilling a total of approximately 5 million barrels of oil into the sea. On September 9, 2010, a 30-inch (76-cm) buried, steel, natural gas pipeline in San Bruno, California, leaked gas and exploded in a residential neighborhood, killing 8 people in their homes and burning a total of 38 homes. Flames were up to 1000 ft (300 m) high, and the initial explosion itself reportedly measured 1.1 on the Richter scale. Finally, on March 11, 2011, a magnitude 9.0 earthquake off the coast of Japan's main island, Honshu, caused a tsunami that crippled the backup power and associated cooling systems for six reactor cores and their spent fuel storage tanks at the Fukushima nuclear power plant. At time of writing, workers trying to bring the crisis under control have been exposed to dangerous levels of radiation, and radioactive water and particulates have been released to the sea and atmosphere. These four disasters, all of which occurred within the past 12 months, were not unprecedented; similar events differing only in detail have happened around the world before, and such events will occur again. Today, developed nations primarily use fossil fuels to create affordable energy for comforts such as lighting, heating and air-conditioning, refrigeration, transportation, education, and entertainment, as well as for powering manufacturing, which creates jobs and a wealth of material goods. In addition to the risks of the existing energy infrastructure that have become obvious through these recent disasters, there is also the ongoing risk of climate change that comes from the vast emissions of greenhouse gases, primarily CO{sub 2}, from the burning of fossil fuels. The implementation of CO{sub 2} capture and storage (CCS) will help mitigate CO{sub 2} emissions from fossil fuel energy, but it also carries with it HSE risks. In my personal interactions with the public and with students, the main concern voiced is whether CO{sub 2} could leak out of the deep reservoirs into which it is injected and rise up out of the ground, smothering people and animals at the ground surface. Another concern expressed is that CO{sub 2} pipelines could fail and cause similar gaseous plumes of CO{sub 2}. The widespread concerns about CO{sub 2} leaking out over the ground surface may be inspired by events that have happened within natural systems in equatorial Africa, in Indonesia, and in Italy. Researchers have been investigating a wide variety of HSE risks of geologic CO{sub 2} storage for some time and have determined that wells are the main potential pathways for significant leakage from the deep subsurface. I discuss the acute HSE risks of CO{sub 2} leakage through wells and from pipelines, and compare the behavior of failures in CO{sub 2} wells and pipelines with oil and gas analogues from which most of our experience derives.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Geomechanical and Hydrogeological Evaluation of a Shallow Hydraulic Fracture at the Devine Fracture Pilot Site, Medina County, Texas

UT-Austin’s Devine Fracture Pilot Site, 50 miles southwest of San Antonio, Texas, has been targeted for a comprehensive, multidisciplinary development of fracture diagnostic techniques that are cross-validated by ground-truth data acquisition near a recently created, 175-ft-deep, horizontal hydraulic fracture (Ahmadian et al. 2018 Demonstration of proof of concept of electromagnetic geophysical methods for high resolution illumination of induced fracture networks. In Proceedings of the SPE Hydraulic Fracturing Technology Conference and Exhibition, The Woodlands, Texas, USA, 23–25 January 2018. SPE-189858-MS.). To evaluate the fracture diagnostic methods at this site, we conducted injection tests with a predefined volumetric flow-rate profile, resembling a diagnostic fracture injection test on September 2020. Subsequently, we developed hydrogeological and geomechanical models based on flow-rate and bottomhole-pressure measurements. History-matching efforts using a simplified layer-cake hydrogeological model resulted in the field-scale formation permeability of 9.87 × 10 –15 m 2 (10 mD) and Darcy-scale fracture permeability. The analysis of the bottomhole pressure and injection-rate history showed that (1) the newly created horizontal fracture was closed adjacent to the injection well pre-injection and (2) the initial pump-pressure increase at a nominal volumetric injection rate led to near-well fracture reopening, fluid conductivity increase, and abrupt injection-rate increase. To overcome hydrogeological-model limitations of predicting fracture reopening throughout injection, we extended the modeling to a finite-element, poroelastic analysis of horizontal-fracture growth using a cohesive-zone model. Using this fracture-reopening model, we improved the history match of the transient-pressure response during the experiment by adjusting the hydromechanical properties. Furthermore, post-injection pressure transient analyses helped reduce uncertainty in the overburden-stress gradient, and the initial hydraulic-fracturing simulation verified the plausibility of achieving the surveyed propped fracture area.

02 PETROLEUM↗
DOE OSTI2013

Study of the interaction of C60 fullerene with human serum albumin in aqueous solution

Concern about the toxicity of engineered nanoparticles, such as the prototypical nanomaterial C60 fullerene, continues to grow. While evidence continues to mount that C60 and its derivatives may pose health hazards, the specific molecular interactions of these particles with biological macromolecules require further investigation. To better understand the interaction of C60 with proteins, the protein human serum albumin (HSA) was studied in solution with C60 at C60:HSA molar ratios ranging from 1:2 to 4:1. HSA is the major protein component of blood plasma and plays a role in a variety of functions, such as the maintenance of blood pH and pressure. The C60-HSA interaction was probed by a combination of circular dichroism (CD) spectroscopy, small-angle neutron scattering (SANS) and atomistic molecular dynamics (MD) simulations to understand C60-driven changes in the structure of HSA in solution. The CD spectroscopy demonstrates that the secondary structure of the protein decreases in -helical content in response to the presence of C60. Similarly, C60 produces subtle changes in the solution conformation of HSA, as evidenced by the SANS data and MD. The data do not indicate that C60 is causing a change in the oligomerization state of the protein. Taken together results demonstrate that C60 interacts with HSA, but it does not strongly perturb the structure of the protein by unfolding it or inducing aggregation, suggesting a mechanism for transporting C60 throughout the body to accumulate in various tissues.

Li, Song↗
DOE OSTI2021

Predicting Fluid Flow Regime, Permeability, and Diffusivity in Mudrocks from Multiscale Pore Characterisation

In geoenergy applications, mudrocks prevent fluids to leak from temporary (H 2 , CH 4 ) or permanent (CO 2 , radioactive waste) storage/disposal sites and serve as a source and reservoir for unconventional oil and gas. Understanding transport properties integrated with dominant fluid flow mechanisms in mudrocks is essential to better predict the performance of mudrocks within these applications. In this study, small-angle neutron scattering (SANS) experiments were conducted on 71 samples from 13 different sets of mudrocks across the globe to capture the pore structure of nearly the full pore size spectrum (2 nm–5 μm). We develop fractal models to predict transport properties (permeability and diffusivity) based on the SANS-derived pore size distributions. The results indicate that transport phenomena in mudrocks are intrinsically pore size-dependent. Depending on hydrostatic pore pressures, transition flow develops in micropores, slip flow in meso- and macropores, and continuum flow in larger macropores. Fluid flow regimes progress towards larger pore sizes during reservoir depletion or smaller pore sizes during fluid storage, so when pressure is decreased or increased, respectively. Capturing the heterogeneity of mudrocks by considering fractal dimension and tortuosity fractal dimension for defined pore size ranges, fractal models integrate apparent permeability with slip flow, Darcy permeability with continuum flow, and gas diffusivity with diffusion flow in the matrix. This new model of pore size-dependent transport and integrated transport properties using fractal models yields a systematic approach that can also inform multiscale multi-physics models to better understand fluid flow and transport phenomena in mudrocks on the reservoir and basin scale.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Noninvasive PET quantitative myocardial blood flow with regadenoson for assessing cardiac allograft vasculopathy in orthotopic heart transplantation patients

Background: Risk stratification and early detection of cardiac allograft vasculopathy (CAV) is essential in orthotopic heart transplantation (OHT) patients. This study assesses the changes in myocardial blood flow (MBF) noninvasively in OHT patients using quantitative cardiac PET with regadenoson. Methods: Twelve patients (Group 1) (8 males, 4 females, mean age 55 ± 7 years) with no history of post OHT myocardial ischemia were enrolled 5.4 ± 2.0 years after OHT. Fifteen patients (Group 2) (9 males, 6 females, mean age 71 ± 9 years) with intermediate pretest probability but not documented evidence for coronary artery disease (CAD) were also included to serve as control. Global and regional MBFs were assessed using dynamic {sup 13}N-NH{sub 3} PET at rest and during regadenoson-induced hyperemia. The coronary flow reserve (CFR) was also calculated as the ratio of hyperemic to resting MBF. Results: Mean regadenoson-induced rate-pressure products were similar in both groups, while there was an increase in resting rate-pressure product in Group 1 patients. Both mean and median values of resting MBF were higher in Group 1 than Group 2 patients (1.33 ± 0.31 and 1.01 ± 0.21 mL/min/g for Groups 1 and 2, respectively, P < .001), while mean hyperemic MBF values were similar in both Groups (2.68 ± 0.84 and 2.64 ± 0.94 mL/min/g, P = NS) but median hyperemic MBF values were lower in Group 1 than Group 2 patients (2.0 vs. 2.60 mL/min/g, P = .018). Both mean and median CFR values demonstrated a significant reduction for Group 1 compared to Group 2 patients (2.07 ± 0.74 vs 2.63 ± 0.48, P = .025). Conclusions: This study suggests that the MBF in OHT patients may be abnormal at resting state with diminished CFR. This hints that the epicardial and microvascular coronary subsystem may be exacerbated after OHT leading to the gradual progression of CAV. [French] French Abstract: Contexte: Cette étude pilote par tomographie a positrons évalue de manière quantitative les changements de perfusion myocardique et le risque de vasculopathie coronaire après transplantation cardiaque chez l’être humain. Méthodes: Douze patients (groupe 1) (8 hommes, 4 femmes, âge moyen 55 ± 7 ans) sans antécédents d'ischémie myocardique post-chirurgicale ont été étudiés après 5,4 ± 2,0 ans après transplantation cardiaque. Quinze patients (groupe 2) (9 hommes, 6 femmes, âge moyen 71 ± 9 ans) avec une probabilité intermédiaire mais sans signes objectifs de maladie coronarienne ont servi de contrôles. Les donnes de perfusion myocardique globales et régionales ont été évaluées par tomographie à positrons l'aide de{sup 13}N-NH3 au repos et durant l'hyperémie induite par le vasodilatateur coronarien régadénoson. La réserve de flux coronarien a été calculée sur base du rapport entre le flux myocardique hyperhémique induit par le régadénoson et le flux myocardique au repos. Résultats: les double produits (fréquence cardiaque x tension artérielle) moyens après régadénoson furent similaires chez les deux groups de patients. Par contre le double produit au repos était plus élevé dans le groupe de patient transplantés. Les valeurs moyennes et médianes de perfusion myocardique globale au repos ont été calculées à 1.33 ± 0.31 ml/min/g dans le groupe de patients transplantés et 1.01 ± 0.21 ml/min/g dans le groupe control (P < 0.001). Après régadénoson, les valeurs moyennes de perfusion myocardique se sont avérées similaires dans les deux groupes (2,68 ± 0,84 et 2,64 ± 0,94 ml/min/g, P > 0.05). Néanmoins les valeurs médianes se sont avérées inferieures dans le groupe 1 comparativement au groupe control (2,0 versus 2,60 ml/min/g; P = 0,018). Les valeurs moyennes et médianes de réserve de flux myocardique mesurées étaient significativement réduites chez les patient transplantés (2,07 ± 0,74) en comparaison aux patients du groupe 2 (2,63 ± 0,48; P = 0.025). Conclusion: La perfusion myocardique au repos peut s’avérer anormale après transplantation cardiaque et s’accompagner d’une diminution de la réserve du flux coronaire. Cette étude pilote suggère que les vaisseaux épicardiques et la micro-vascularisation du myocarde peuvent être atteints après transplantation et conduire à la maladie coronaire du greffon. [Spanish] Spanish Abstract: Antecedentes: la estratificación de riesgo y detección temprana de la vasculopatía del aloinjerto cardiaco (VAC) es esencial en los pacientes con trasplante cardiaco ortotópico (TCO). El presente estudio evalúa de forma no invasiva los cambios en el flujo sanguíneo miocárdico (FSM) en pacientes con TCO utilizando el PET cardiaco cuantitativo con regadenoson. Métodos: Doce pacientes (Grupo 1) (8 hombres, 4 mujeres, edad promedio 55 ± 7 años) sin historia de isquemia miocárdica posterior al TCO fueron incluidos después de 5.4 ± 2.0 años de ser trasplantados. Quince pacientes (Grupo 2) (9 hombres, 6 mujeres, edad promedio 71 ± 9 años) con probabilidad pre-prueba intermedia pero sin evidencia documentada de enfermedad arterial coronaria (EAC) fueron incluidos como grupo control. El FSM global y regional fueron evaluados utilizando el estudio PET dinámico con {sup 13}N-NH{sub 3} en reposo y durante la inducción de hiperemia con regadenoson. La reserva de flujo coronario (RFC) también fue calculada como la proporción entre el FSM hiperémico y el de reposo. Resultados: el producto de velocidad-presión promedio inducido por regadenoson fue similar en ambos grupos, mientras que existió un incremento de este producto velocidad-presión durante el reposo en el Grupo 1 de pacientes. Los valores de la media y mediana del FSM de reposo fueron mayores en el Grupo 1 que el Grupo 2 de pacientes (1.33 ± 0.31 y 1.01 ± 0.21 mL/min/g para los Grupos 1 y 2, respectivamente, P < 0.001). La media de los valores del FSM hiperémico fueron similares en ambos grupos (2.68 ± 0.84 and 2.64 ± 0.94 mL/min/g, P = NS), sin embargo la mediana fue menor en el Grupo 1 que en el Grupo 2 (2.0 vs. 2.60 mL/min/g, P = .018). Tanto la media como la mediana para los valores de la RFC demostraron una disminución significativa en el Grupo 1 comparada con el Grupo 2 (2.07 ± 0.74 vs. 2.63 ± 0.48, P = 0.025). Conclusiones: El presente estudio sugiere que el FSM en pacientes con TCO puede estar alterado en reposo con una RFC disminuida. Esto indica que los sistemas coronarios epicardico y microvascular pudieran estar inflamados posterior al TCO conduciendo a una progresión gradual de la VAC. [Chinese] Chinese Abstract: 背景: 对于原位心脏移植 (OHT) 病人, 早期检测移植心脏血管病变 (CAV) 和进行危险分层是必要的。 本研究拟通过类伽腺苷定 心脏 PET 显像, 非侵入性地评估 OHT 病人心肌血流 (MBF) 的变化。 方法: 研究对象分为两组。 第一组, 12个病人 (8 男, 4女, 平均 55 ± 7岁), OHT 后 5.4 ± 2.0 年, 没有 OHT 后心肌缺血。 第二组 (对照组), 15 个病人 (9 男, 6 女, 平均 71 ± 9 岁), 中等冠心病可能, 但尚未确诊。 分别于静息及类伽腺苷药物负荷下, 动态采集 {sup 13}N-NH{sub 3} PET 图像, 获得整体和局部 MBF。冠脉血流储备 (CFR) 通过负荷 MBF /静息 MBF 计算而得。 结果: 类伽腺苷负荷时, 反映心肌耗氧 的心率血压乘积在两组间没有差异, 但在静息时, 第一组明显高于第二组。静息时, 第一组 MBF 的平均值高于第二组 (1.33 ± 0.31 vs. 1.01 ± 0.21 mL/min/g, P < 0.001); 负荷时, 两组 MBF 的平均值无差异 (2.68 ± 0.84 vs. 2.64 ± 0.94 mL/min/g, P = NS), 但 MBF 的中位数第一组要低于第二组 (2.0 vs. 2.60 mL/min/g, P = 0.018), 且第一组 CFR 的平均值明显低于第二组 (2.07 ± 0.74 vs. 2.63 ± 0.48, P = 0.025)。 结论: 在原位心脏移植病人中, 冠脉血流储备以及静息心肌血流 均呈现明显异常。提示原位心脏移植后, 冠状动脉心外膜血管与微小血管功能均受损, 进而将逐渐导致移植心脏血管病变。 关键词: 动态PET, 类伽腺苷, 冠状动脉血流储备, 原位心脏移植, 移植心脏血管病变。.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

Repeatable and reproducible measurements of myocardial oxidative metabolism, blood flow and external efficiency using {sup 11}C-acetate PET

Background: Non-invasive approaches to investigate myocardial efficiency can help track the progression of heart failure (HF). This study evaluates the repeatability and reproducibility of {sup 11}C-acetate positron emission tomography (PET) imaging of oxidative metabolism. Methods and results: Dynamic {sup 11}C-acetate PET scans were performed at baseline and followup (47 ± 22 days apart) in 20 patients with stable HF with reduced ejection fraction. Two observers blinded to patients’ clinical data used FlowQuant{sup ®} to evaluate test–retest repeatability, as well as intra- and inter-observer reproducibility of {sup 11}C-acetate tracer uptake and clearance rates, for the measurement of myocardial oxygen consumption (MVO{sub 2}), myocardial external efficiency (MEE), work metabolic index (WMI), and myocardial blood flow. Reproducibility and repeatability were evaluated using intra-class-correlation (ICC) and Bland–Altman coefficient-of-repeatability (CR). Test–retest correlations and repeatability were better for MEE and WMI compared to MVO{sub 2}. All intra- and inter-observer correlations were excellent (ICC = 0.95-0.99) and the reproducibility values (CR = 3%-6%) were significantly lower than the test–retest repeatability values (22%-54%, P < 0.001). Repeatability was improved for all parameters using a newer PET–computed tomography (CT) scanner compared to older PET-only instrumentation. Conclusion: {sup 11}C-acetate PET measurements of WMI and MEE exhibited excellent test–retest repeatability and operator reproducibility. Newer PET–CT scanners may be preferred for longitudinal tracking of cardiac efficiency. [French] French Abstract: Contexte: Les examens non invasifs de la fonction myocardique aident à suivre la progression de l’insuffisance cardiaque. Dans ce travail, nous avons évalué la répétabilité et la reproductibilité de l’étude du métabolisme oxydatif du myocarde par imagerie tomographique à positrons avec l’acétate marqué au carbone 11. Méthodes et résultats: Une étude de base et un second examen TEP dynamique à l’ acétate marqué au carbone 11 ont été réalisés (47 ± 22 jours) chez 20 patients présentant une insuffisance cardiaque stable avec une fraction d’éjection réduite. Sans aucune connaissance des données cliniques et au moyen du programme FlowQuant®, deux observateurs ont évalué la répétabilité des TEPs de base et de leur suivi, la reproductibilité intra- et inter-observateur, l’absorption et la clearance du traceur, la mesure de la consommation d’oxygène du myocarde (MVO2), l’efficacité contractile du myocarde (MEE), l’index métabolique du travail myocardique (WMI) et le débit sanguin myocardique (MBF). La reproductibilité et la répétabilité ont été évaluées en utilisant la corrélation intra-classe (ICC) et le coefficient de répétabilité Altman (CR). Les corrélations entre les études de base et leur suivi et la répétabilité des données se sont avérées supérieures pour les paramètres MEE et WMI par rapport à MVO2. Toutes les corrélations intra- et inter-observateurs furent excellentes (ICC = 0,95-0,99). Les valeurs de reproductibilité (CR = 3-6%) furent significativement inférieures aux valeurs de répétabilité (22-54%, p <0.001). La répétabilité des paramètres mesurés s’est avérée supérieure avec un scanner TEP-TDM de nouvelle génération par rapport à l’utilisation de la TEP sans TDM Conclusion: Les mesures réalisées dans cette étude TEP 11C-acétate montre une excellent répétabilité et reproductibilité des paramètres WMI et WMI entre les examens de base et leur suivi effectués par des opérateurs différents. Les nouveaux scanners TEP-TDM devraient être préférés pour le suivi longitudinal de la fonction cardiaque. [Spanish] Spanish Abstract: Antecedentes: el abordaje no invasivo para investigar la eficiencia miocárdica puede ayudar en el seguimiento de la progresión de la insuficiencia cardíaca. Este estudio evalúa la repetibilidad y la reproducibilidad del estudio de metabolismo oxidativo con PET 11C-acetato. Métodos y resultados: Se realizaron estudios de PET 11C-acetato dinámicos al inicio y durante el seguimiento (47 ± 22 días de diferencia) en 20 pacientes con insuficiencia cardíaca estable y fracción de eyección reducida. Dos observadores cegados a los datos clínicos de los pacientes utilizaron FlowQuant® para evaluar la repetibilidad de la prueba-reprueba, así como la reproducibilidad intra e interobservador de la captación de radiotrazador 11C-acetato y sus tasas de eliminación, la medición del consumo miocárdico de oxígeno (MVO2), la eficiencia externa miocardica (EEM), el índice trabajo-metabólico (ITM) y flujo sanguíneo miocárdico (FSM). La reproducibilidad y la repetibilidad se evaluaron mediante la correlación intraclase (ICC) y el coeficiente de repetibilidad (CR) de Bland-Altman. Las correlaciones Prueba-Reprueba y la repetibilidad fueron mejores para la EEM y el ITM en comparación con el MVO2. Todas las correlaciones intra e interobservador fueron excelentes (ICC = 0.95-0.99) y los valores de reproducibilidad (CR = 3-6%) fueron significativamente menores que los valores de repetibilidad prueba-reprueba (22-54%, p <0.001). La repetibilidad fue mejor para todos los parámetros utilizando un equipo PET-TC más nuevo en comparación con un equipo PET sin CT. Conclusión: las mediciones del PET con 11C-acetato del ITM y EEM mostraron una excelente repetibilidad prueba-preprueba y reproducibilidad del operador. Los nuevos equipos PET-CT pueden ser elegidos para el seguimiento longitudinal de la eficiencia miocárdica. [Chinese] Chinese Abstract: 背景: 采用非侵入式方法来研究心肌代谢效率可以帮助追踪心力衰竭的过程。本研究评估利用碳-11 醋酸盐为 PET 显影剂行氧化代谢成像的可重复性和可再现性。 方法和结果: 纳入射血分数减低的 20 名稳定性心衰患者,对患者基线和 47±22 天随访都进行碳-11 醋酸盐 PET 扫描。为测量心肌耗氧量(MVO{sub 2}), 心肌外效率(MEE), 工作代谢指标(WMI)和心肌血流量(MBF), 两名观察者按照双盲的方法利用 FlowQuant®对碳-11 醋酸盐的摄取率和清空率进行了重复性测试以及不同观察者之间的可再现性测试。采用组内相关系数(ICC)和 Bland Altman 可重复性系数(CR)分别对可再现性和可重复性进行评估。MEE 和 WMI 的两次试验系数和可重复性优于MVO{sub 2}。所有观察者之间的相关系数都较好(ICC=0.95-0.99),可再现性系数的值(CR=3-6%)明显低于两次试验可重复性的值(22-54%, P<0.001)。相比于旧的只有 PET 的设备, 采用新型 PET-CT 扫描仪能够使所有参数的可再现性都有所提高。 结论: 碳-11醋酸盐 PET 显像测量 WMI 和 MEE 有很好的可重复性和可再现性。新的 PET-CT 扫描仪可能更适合于心脏代谢效率的长期追踪。.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Automatic generation and simulation of urban building energy models based on city datasets for city-scale building retrofit analysis

Buildings in cities consume 30–70% of total primary energy, and improving building energy efficiency is one of the key strategies towards sustainable urbanization. Urban building energy models (UBEM) can support city managers to evaluate and prioritize energy conservation measures (ECMs) for investment and the design of incentive and rebate programs. This paper presents the retrofit analysis feature of City Building Energy Saver (CityBES) to automatically generate and simulate UBEM using EnergyPlus based on cities’ building datasets and user-selected ECMs. CityBES is a new open web-based tool to support city-scale building energy efficiency strategic plans and programs. The technical details of using CityBES for UBEM generation and simulation are introduced, including the workflow, key assumptions, and major databases. Also presented is a case study that analyzes the potential retrofit energy use and energy cost savings of five individual ECMs and two measure packages for 940 office and retail buildings in six city districts in northeast San Francisco, United States. The results show that: (1) all five measures together can save 23–38% of site energy per building; (2) replacing lighting with light-emitting diode lamps and adding air economizers to existing heating, ventilation and air-conditioning (HVAC) systems are most cost-effective with an average payback of 2.0 and 4.3 years, respectively; and (3) it is not economical to upgrade HVAC systems or replace windows in San Francisco due to the city's mild climate and minimal cooling and heating loads. Furthermore, the CityBES retrofit analysis feature does not require users to have deep knowledge of building systems or technologies for the generation and simulation of building energy models, which helps overcome major technical barriers for city managers and their consultants to adopt UBEM.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2017

Bidirectional low temperature district energy systems with agent-based control: Performance comparison and operation optimization

Bidirectional low temperature networks are a novel concept that promises more efficient heating and cooling of buildings. Early research shows theoretical benefits in terms of exergy efficiency over other technologies. Pilot projects indicate that the concept delivers good performance if heating and cooling demands are diverse. However, the operation of these networks is not yet optimized and there is no quantification of the benefits over other technologies in various scenarios. Moreover, there is a lack of understanding of how to integrate and control multiple distributed heat and cold sources in such networks. Thus, this paper develops a control concept based on a temperature set point optimization and agent-based control which allows the modular integration of an arbitrary number of sources and consumers. Afterwards, the concept is applied to two scenarios representing neighborhoods in San Francisco and Cologne with different heating and cooling demands and boundary conditions. The performance of the system is then compared to other state-of-the-art heating and cooling solutions using dynamic simulations with Modelica. The results show that bidirectional low temperature networks without optimization produce 26% less emissions in the San Francisco scenario and 63% in the Cologne scenario in comparison to the other heating and cooling solutions. Savings of energy costs are 46% and 27%, and reductions of primary energy consumption 52% and 72%, respectively. The presented operation optimization leads to electricity use reductions of 13% and 41% when compared to networks with free-floating temperature control and the results indicate further potential for improvement. The study demonstrates the advantage of low temperature networks in different situations and introduces a control concept that is extendable for real implementation.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2014

Analyzing source apportioned methane in northern California during Discover-AQ-CA using airborne measurements and model simulations

This study analyzes source apportioned methane (CH 4 ) emissions and atmospheric mixing ratios in northern California during the Discover-AQ-CA field campaign using airborne measurement data and model simulations. Source apportioned CH 4 emissions from the Emissions Database for Global Atmospheric Research (EDGAR) version 4.2 were applied in the 3-D chemical transport model GEOS-Chem and analyzed using airborne measurements taken as part of the Alpha Jet Atmospheric eXperiment over the San Francisco Bay Area (SFBA) and northern San Joaquin Valley (SJV). During the time period of the Discover-AQ-CA field campaign EDGAR inventory CH 4 emissions were ~5.30 Gg day –1 (Gg = 1.0 × 10 9 g) (equating to ~1.90 × 10 3 Gg yr –1 ) for all of California. According to EDGAR, the SFBA and northern SJV region contributes ~30% of total CH 4 emissions from California. Source apportionment analysis during this study shows that CH 4 mixing ratios over this area of northern California are largely influenced by global emissions from wetlands and local/global emissions from gas and oil production and distribution, waste treatment processes, and livestock management. Model simulations, using EDGAR emissions, suggest that the model under-estimates CH 4 mixing ratios in northern California (average normalized mean bias (NMB) = –5.2% and linear regression slope = 0.20). The largest negative biases in the model were calculated on days when large amounts of CH 4 were measured over local emission sources and atmospheric CH 4 mixing ratios reached values >2.5 parts per million. Sensitivity emission studies conducted during this research suggest that local emissions of CH 4 from livestock management processes are likely the primary source of the negative model bias. These results indicate that a variety, and larger quantity, of measurement data needs to be obtained and additional research is necessary to better quantify source apportioned CH 4 emissions in California.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

The value of adding black carbon to community monitoring of particulate matter

Low-cost particulate matter (PM) sensors are increasingly used by researchers, public health agencies, and the public to measure spatial and temporal variations in air pollution, which can inform strategies for community air pollution reduction. While low-cost PM sensors provide a valuable measure of harmful fine particulate matter (PM 2.5 ), a significant portion of ambient PM 2.5 is typically the secondary product of air pollution emitted by varied sources outside of community boundaries. In contrast, concentrations of black carbon (BC), a component of PM 2.5 , are directly emitted by a few specific sources, such as diesel engines within communities. Motivated by community organizations seeking to understand persistent sources of local pollution, this study deployed a suite of custom-built BC sensors alongside a network of low-cost PM sensors for four weeks in two seasons at 50 stationary locations in the adjacent cities of Richmond, North Richmond, and San Pablo, California, east of the San Francisco Bay. Concentrations of BC varied more than PM 2.5 both temporally and spatially. Monthly network-average BC was 3×higher in winter than late spring, while PM 2.5 was only 10% lower. In both seasons, average PM 2.5 concentrations at two-thirds of sites were within ±10% of the network average, whereas two-thirds of sites had BC levels outside of ±10% of the network-average concentration. The most and least polluted locations were more persistent across seasons for BC than PM 2.5 , and the temporal dynamics of BC at these sites were similar, signifying that they are impacted by the same emission sources. Together, these spatiotemporal trends show that BC is a better indicator of the proximity and activity of local pollution sources than PM 2.5 . Thus, including BC in addition to PM 2.5 in community monitoring networks can provide additional insights about local sources of air pollution.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

The helix-to-sheet transition of an HIV-1 fusion peptide derivative changes the mechanical properties of lipid bilayer membranes

Here, a short sequence on the gp41 envelope protein of HIV-1 is integral to infection by the virus. Without this sequence, termed the fusion peptide (FP), the virus is far less effective at fusing with the cellular membrane. One of the interesting features of the isolated FP is that it transitions between an α-helical conformation and a β-sheet conformation in lipid bilayer membranes as a function of lipid composition and concentration, and the transition correlates with fusion. To better understand how the conformations of the FP impact lipid bilayer membranes, a variant of the FP that does not strongly promote fusion, termed gp41rk, was studied. Circular dichroism spectroscopy, dynamic light scattering, small-angle neutron scattering (SANS) and neutron spin echo spectroscopy (NSE) were used to relate the conformation of gp41rk to the structure and mechanical properties of lipid bilayer membrane vesicles composed of a 7:3 molar ratio mixture of 1,2-dimyristoyl- sn -glycero-3-phosphocholine and 1,2-dimyristoyl- sn -glycero-3-phospho-(1'-rac-glycerol). At a peptide-to-lipid ratio (P/L) of 1/200, it adopts an α-helical conformation, while gp41rk is a β-sheet at a P/L of 1/50 in the unilamellar vesicles. SANS reveals that the lipid bilayer membrane becomes thicker when gp41rk adopts a β-sheet conformation, which indicates that the high-concentration state of the peptide increases the order of the lipid acyl chains. At the same time, NSE demonstrates that the bilayer becomes more rigid, demonstrating that the β-sheet conformation, which correlates with fusion for the native FP sequence, stiffens the bilayer. The results have implications for the function of the FP.

60 APPLIED LIFE SCIENCES↗