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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Optimization of Window Positions for Wind-Driven Natural Ventilation Performance

This paper optimizes opening positions on building facades to maximize the natural ventilation’s potential for ventilation and cooling purposes. The paper demonstrates how to apply computational fluid dynamics (CFD) simulation results to architectural design processes, and how the CFD-driven decisions impact ventilation and cooling: (1) background: A CFD helps predict the natural ventilation’s potential, the integration of CFD results into design decision-making has not been actively practiced; (2) methods: Pressure data on building facades were obtained from CFD simulations and mapped into the 3D modeling environment, which were then used to identify optimal positions of two openings of a zone. The effect of the selected opening positions was validated with building energy simulations; (3) results: The cross-comparison study of different window positions based on different geographical locations quantified the impact on natural ventilation effectiveness; and (4) conclusions: The optimized window position was shown to be effective, and some optimal solutions contradicted the typical cross-ventilation strategy.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2022

Non‐Traditional Positively‐Biased Narrow‐Band Perovskite Single‐Crystal Photodetectors Enabled by Interfacial Engineering

Abstract The positive bias in theory narrows down the depletion region and thus results in significant charge injection, which should be detrimental to charge generation and collection performance for traditional photodetectors. Here, instead, it is found that the external quantum efficiency (EQE) is increased by more than 50 times when the photodetector is positively biased. A positive bias of +6 V drives ion migration of Br − and Cs + towards the anode and cathode, respectively, leading to self‐doping within bulk single crystals to form an advantageous p‐i‐n junction for better charge collection in the devices. Meanwhile, the injected holes are allowed to tunnel through the cesium lead bromide/fullerene interface to reach the cathode which also significantly contributes to the enhancement of EQE in the forward‐biased devices. The positively‐biased narrow‐band (full width at half maxima (FWHM) = 16 nm) photodetectors exhibit a specific detectivity of 6.5 × 10 10 Jones at 550 nm, along with the −3 dB cutoff frequency of 2776 Hz. By manipulating charge injection and ion migration using interfacial engineering, a class of non‐traditional, positively‐biased, and highly narrow‐band photodetectors is demonstrated, which offers an alternative design strategy for imaging, biosensing, automatic control, and optical communication.

Li, Junchi↗
DOE OSTI2024

Concurrent Inter-Model Spread of Boreal Winter Westerly Jet Meridional Positions Between the Northern and Southern Hemispheres in CMIP6 Models

Here, this study investigates the inter-model spread of climatological extratropical westerly jets in boreal winter, using the historical simulation of 52 Coupled Model Intercomparison Project phase 6 (CMIP6) models from 1851 to 2014. The results show that there is a substantial spread in the latitude of the upper-tropospheric westerly jet across models, characterised by large inter-model standard deviations to both the poleward and equatorward sides of the jet axis, although the multi-model ensemble mean (MME) performs well in simulating meridional position of westerly jets. Furthermore, we detect the consistency of inter-model jet position spread between the Northern and Southern Hemispheres, based on the inter-model empirical orthogonal function (EOF) decomposition and correlation of regional-averaged zonal winds. Specifically, the models that simulate the westerly jets poleward/equatorward relative to the MME position in one hemisphere also tend to simulate the jets poleward/equatorward in the other hemisphere. Accordingly, we define a global jet spread index to depict the concurrence of jet shift in the two hemispheres. The results of inter-model regression analyses based on this index indicate that the models positioning the jets poleward than the MME tend to simulate a wider Hadley Cell, a poleward-shifted Ferrel Cell in the Southern Hemisphere, enhanced precipitation in the subtropics and suppressed precipitation in the tropics, and warmer sea surface temperatures in the subtropics and mid-latitudes. The present results suggest that improving the simulation of jet positions in climate models requires a comprehensive consideration of thermal states in the tropics and subtropics/mid latitudes.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

UV-POSIT: Web-Based Tools for Rapid and Facile Structural Interpretation of Ultraviolet Photodissociation (UVPD) Mass Spectra

UV-POSIT (Ultraviolet Photodissociation Online Structure Interrogation Tools) is a suite of web-based tools designed to facilitate the rapid interpretation of data from native mass spectrometry experiments making use of 193 nm ultraviolet photodissociation (UVPD). The suite includes four separate utilities which assist in the calculation of fragment ion abundances as a function of backbone cleavage sites and sequence position; the localization of charge sites in intact proteins; the calculation of hydrogen elimination propensity for a-type fragment ions; and mass-offset searching of UVPD spectra to identify unknown modifications and assess false positive fragment identifications. UV-POSIT is implemented as a Python/Flask web application hosted at http://uv-posit.cm.utexas.edu . UV-POSIT is available under the MIT license, and the source code is available at https://github.com/jarosenb/UV-POSIT . .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Triptolide inhibits proliferation of Epstein–Barr virus-positive B lymphocytes by down-regulating expression of a viral protein LMP1

Highlights: • Triptolide inhibits proliferation of EBV-positive lymphoma cells in vitro and in vivo. • Triptolide reduces expression of LMP1 by decreasing its transcription level. • Triptolide inhibits ED-L1 promoter activity. - Abstract: Epstein–Barr virus (EBV) infects various types of cells and mainly establishes latent infection in B lymphocytes. The viral latent membrane protein 1 (LMP1) plays important roles in transformation and proliferation of B lymphocytes infected with EBV. Triptolide is a compound of Tripterygium extracts, showing anti-inflammatory, immunosuppressive, and anti-cancer activities. In this study, it is determined whether triptolide inhibits proliferation of Epstein–Barr virus-positive B lymphocytes. The CCK-8 assays were performed to examine cell viabilities of EBV-positive B95-8 and P3HR-1 cells treated by triptolide. The mRNA and protein levels of LMP1 were examined by real time-PCR and Western blotting, respectively. The activities of two LMP1 promoters (ED-L1 and TR-L1) were determined by Dual luciferase reportor assay. The results showed that triptolide inhibited the cell viability of EBV-positive B lymphocytes, and the over-expression of LMP1 attenuated this inhibitory effect. Triptolide decreased the LMP1 expression and transcriptional levels in EBV-positive B cells. The activity of LMP1 promoter ED-L1 in type III latent infection was strongly suppressed by triptolide treatment. In addition, triptolide strongly reduced growth of B95-8 induced B lymphoma in BALB/c nude mice. These results suggest that triptolide decreases proliferation of EBV-induced B lymphocytes possibly by a mechanism related to down-regulation of the LMP1 expression.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Different players generate positive responses in two in vitro cytokine assay formats with aqueous and immobilized TGN1412 analog

Highlights: • Cytokine producing cells in the two major in vitro assay formats were compared. • T-cell activation contributed to the positive response to CD28SA in PBMC assay. • Monocytes and granulocytes contributed to the positive response to CD28SA in WBCA. • Different players generated the positive responses in the two assays. To detect potential risk of severe cytokine release syndrome, in vitro assay formats with human cells have been developed. The two major testing platforms are a combination of whole blood with aqueous-phase test articles (whole blood cytokine assay, WBCA) and peripheral blood mononuclear cells with solid-phase articles (PBMC assay). Significant induction of cytokines was seen in both assays after treatment with a widely used control agent, TGN1412 or its analog CD28SA, but the WBCA cytokine profile differed from what was expected from clinical experience. In the WBCA, potential risk of CD28SA was detected by elevation of IL-8 whereas IL-2, a key cytokine after stimulation of CD28, was not induced in approximately 40% of donor samples. Therefore, further mechanistic understanding of the different responses in the in vitro assay was needed. In this study of donor samples treated with CD28SA, we compared the induction of cytokines and identified the cytokine-producing cells in the two assays. IL-2 was markedly elevated in all the donors in the PBMC assay but only in 1 of 3 donors in the WBCA. IL-8, the most sensitive biomarker in the WBCA, was produced by monocytes and granulocytes. T cells, the most relevant player in the PBMC assay with CD28SA, did not contribute to the positive response seen in two donors in the WBCA, which suggests that different players caused the positive cytokine responses to CD28SA in the two assays.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2020

Deposition of sulfate aerosols with positive Δ 33 S in the Neoarchean

Anomalous sulfur isotope compositions present in Archean rocks have been intensely scrutinized over the last 20 years because they record key aspects of Earth's atmospheric composition prior to the appearance of free molecular oxygen ca. 2.3 billion years ago. These isotopic compositions can be described as mass anomalous fractionations (MAF) and are produced in the atmosphere as UV light interacts with SO 2 molecules. Most interpretations suggest that atmospheric processes generate a reduced S-phase with a positive ( 33 S-enriched) MAF signature, as measured in pyrites, and an oxidized S-phase with a negative anomaly, as measured in bedded barite deposits. However, recent data for carbonate-associated sulfate (CAS) — a direct proxy for the isotopic composition of sulfur from seawater sulfate — in Neoarchean rocks showed no such negative values, but rather the opposite. To understand if the positive MAF anomalies we measured in Neoarchean CAS reflect secondary processes (diagenetic, metamorphic, handling) instead of original signals of Archean seawater sulfate, we collected additional sample suites with various degrees of preservation and metamorphic alteration across the Campbellrand-Malmani platform in South Africa. Results illustrate that within this comprehensive suite, less-altered samples all contain positive MAF values while secondary processes tend to either remove CAS from the sample and/or decrease the 33 S-enrichment. This positive MAF signal in sulfate is therefore reasonably interpreted as a primary depositional origin, and implies that the assumption that sulfate always carries a negative MAF anomaly throughout the Archean rock record needs to be reconsidered. Our CAS observations suggest that future experiments and calculations should also consider atmospheric and/or sulfur cycling processes that can produce oxidized sulfur with a positive MAF signature.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2012

Prospective Assessment of Optimal Individual Position (Prone Versus Supine) for Breast Radiotherapy: Volumetric and Dosimetric Correlations in 100 Patients

Purpose: Damage to heart and lung from breast radiotherapy is associated with increased cardiovascular mortality and lung cancer development. We conducted a prospective study to evaluate which position is best to spare lung and heart from radiotherapy exposure. Methods and Materials: One hundred consecutive Stage 0-IIA breast cancer patients consented to participate in a research trial that required two computed tomography simulation scans for planning both supine and prone positions. The optimal position was defined as that which best covered the contoured breast and tumor bed while it minimized critical organ irradiation, as quantified by the in-field heart and lung volume. The trial was designed to plan the first 100 patients in each position to study correlations between in-field volumes of organs at risk and dose. Results: Fifty-three left and 47 right breast cancer patients were consecutively accrued to the trial. In all patients, the prone position was optimal for sparing lung volume compared to the supine setup (mean lung volume reduction was 93.5 cc for right and 103.6 cc for left breast cancer patients). In 46/53 (87%) left breast cancer patients best treated prone, in-field heart volume was reduced by a mean of 12 cc and by 1.8 cc for the other 7/53 (13%) patients best treated supine. As predicted, supine-prone differences in in-field volume and mean dose of heart and lung were highly correlated (Spearman's correlation coefficient for left breast cancer patients was 0.90 for heart and 0.94 for lung and 0.92 for right breast cancer patients for lung). Conclusions: Prone setup reduced the amount of irradiated lung in all patients and reduced the amount of heart volume irradiated in 87% of left breast cancer patients. In-field organ volume is a valid surrogate for predicting dose; the trial continued to the planned target of 400.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

PET Motion Compensation for Radiation Therapy Using a CT-Based Mid-Position Motion Model: Methodology and Clinical Evaluation

Purpose: Four-dimensional positron emission tomography (4D PET) imaging of the thorax produces sharper images with reduced motion artifacts. Current radiation therapy planning systems, however, do not facilitate 4D plan optimization. When images are acquired in a 2-minute time slot, the signal-to-noise ratio of each 4D frame is low, compromising image quality. The purpose of this study was to implement and evaluate the construction of mid-position 3D PET scans, with motion compensated using a 4D computed tomography (CT)-derived motion model. Methods and Materials: All voxels of 4D PET were registered to the time-averaged position by using a motion model derived from the 4D CT frames. After the registration the scans were summed, resulting in a motion-compensated 3D mid-position PET scan. The method was tested with a phantom dataset as well as data from 27 lung cancer patients. Results: PET motion compensation using a CT-based motion model improved image quality of both phantoms and patients in terms of increased maximum SUV (SUV{sub max}) values and decreased apparent volumes. In homogenous phantom data, a strong relationship was found between the amplitude-to-diameter ratio and the effects of the method. In heterogeneous patient data, the effect correlated better with the motion amplitude. In case of large amplitudes, motion compensation may increase SUV{sub max} up to 25% and reduce the diameter of the 50% SUV{sub max} volume by 10%. Conclusions: 4D CT-based motion-compensated mid-position PET scans provide improved quantitative data in terms of uptake values and volumes at the time-averaged position, thereby facilitating more accurate radiation therapy treatment planning of pulmonary lesions.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Review of the Clinical and Biologic Aspects of Human Papillomavirus-Positive Squamous Cell Carcinomas of the Head and Neck

Human papillomavirus (HPV), a known etiology of a subset of head-and-neck squamous cell carcinomas (HNCs), causes numerous alterations in normal cellular functions. This article reviews the biology, detection, and treatment of HPV-positive HNC. The role of HPV oncoproteins in tumor development, the natural history of HPV infection, and risk factors for and prevention of transmission of oral HPV are considered. Commonly used methods for detecting HPV infection, including limitations of these methods, are discussed to aid the practicing clinician in using these tests in their clinical practice. Clinical characteristics of HPV-positive HNC, including potential explanations for the improved outcomes seen in patients with HPV-positive HNC, are assessed. Ongoing clinical trials specific for patients with HPV-positive HNC are described, and areas in need of additional research are summarized. Until the results of ongoing trials are known, treatment of HPV-positive HNC should not differ in clinical practice from treatment of similar non-HPV related cancers.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Continuous Monitoring and Intrafraction Target Position Correction During Treatment Improves Target Coverage for Patients Undergoing SBRT Prostate Therapy

Purpose: To compare the potential benefits of continuous monitoring of prostate position and intervention (CMI) using 2-mm displacement thresholds during stereotactic body radiation therapy (SBRT) treatment to those of a conventional image-guided procedure involving single localization prior to treatment. Methods and Materials: Eighty-nine patients accrued to a prostate SBRT dose escalation protocol were implanted with radiofrequency transponder beacons. The planning target volume (PTV) margin was 5 mm in all directions, except for 3 mm in the posterior direction. The prostate was kept within 2 mm of its planned position by the therapists halting dose delivery and, if necessary, correcting the couch position. We computed the number, type, and time required for interventions and where the prostate would have been during dose delivery had there been, instead, a single image-guided setup procedure prior to each treatment. Distributions of prostate displacements were computed as a function of time. Results: After the initial setup, 1.7 interventions per fraction were required, with a concomitant increase in time for dose delivery of approximately 65 seconds. Small systematic drifts in prostate position in the posterior and inferior directions were observed in the study patients. Without CMI, intrafractional motion would have resulted in approximately 10% of patients having a delivered dose that did not meet our clinical coverage requirement, that is, a PTV D95 of >90%. The posterior PTV margin required for 95% of the dose to be delivered with the target positioned within the PTV was computed as a function of time. The margin necessary was found to increase by 2 mm every 5 minutes, starting from the time of the imaging procedure. Conclusions: CMI using a tight 2-mm displacement threshold was not only feasible but was found to deliver superior PTV coverage compared with the conventional image-guided procedure in the SBRT setting.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Adjuvant Radiation Therapy for Margin-Positive Vulvar Squamous Cell Carcinoma: Defining the Ideal Dose-Response Using the National Cancer Data Base

Purpose: Positive surgical margins after radical vulvectomy for vulvar cancer portend a high risk for local relapse, which may be challenging to salvage. We assessed the impact of adjuvant radiation therapy (aRT) on overall survival (OS) and the dose-response relationship using the National Cancer Data Base. Methods and Materials: Patients with vulvar squamous cell carcinoma who underwent initial extirpative surgery with positive margins from 1998 to 2012 were included. Factors associated with aRT and specific dose levels were analyzed using logistic regression. Log-rank and multivariable Cox proportional hazards modeling were used for OS analysis. Results: We identified 3075 patients with a median age of 66 years (range, 22-90 years); the median follow-up time was 36.4 months (interquartile range [IQR] 15.4-71.0 months). Stage IA/B disease represented 41.2% of the cohort. Sixty-three percent underwent lymph node assessment, with a 45% positivity rate. In total, 1035 patients (35.3%) received aRT, with a median dose of 54.0 Gy (IQR 48.6-60.0 Gy). The 3-year OS improved from 58.5% to 67.4% with aRT (P<.001). On multivariable analysis, age, Charlson-Deyo score ≥1, stage ≥II, tumors ≥4 cm, no aRT, and adverse nodal characteristics led to inferior survival. Dose of aRT was positively associated with OS as a continuous variable on univariate analysis (P<.001). The unadjusted 3-year OS for dose subsets 30.0 to 45.0 Gy, 45.1 to 53.9 Gy, 54.0 to 59.9 Gy, and ≥60 Gy was 54.3%, 55.7%, 70.1%, and 65.3%, respectively (P<.001). Multivariable analysis using a 4-month conditional landmark revealed that the greatest mortality reduction occurred in cumulative doses ≥54 Gy: 45.1 to 53.9 Gy (hazard ratio [HR] 0.94, P=.373), 54.0 to 59.9 Gy (HR 0.75, P=.024), ≥60 Gy (HR 0.71, P=.015). No survival benefit was seen with ≥60 Gy compared with 54.0 to 59.9 Gy (HR 0.95, P=.779). Conclusions: Patients with vulvar squamous cell carcinoma and positive surgical margins derive an OS benefit from aRT with a seemingly optimal dose in the range of 54.0 to 59.9 Gy.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Using kV-kV and CBCT imaging to evaluate rectal cancer patient position when treated prone on a newly available belly board

The goal of this work was to use daily kV-kV imaging and weekly cone-beam CT (CBCT) to evaluate rectal cancer patient position when treated on a new couch top belly board (BB). Quality assurance (QA) of the imaging system was conducted weekly to ensure proper performance. The positional uncertainty of the combined kV-kV image match and subsequent couch move was found to be no more than {+-} 1.0 mm. The average (1 SD) CBCT QA phantom match was anterior-posterior (AP) = -0.8 {+-} 0.2 mm, superior-inferior (SI) = 0.9 {+-} 0.2 mm, and left-right (LR) = -0.1 {+-} 0.1 mm. For treatment, a set of orthogonal kV-kV images were taken and a bony anatomy match performed online. Moves were made along each axis (AP, SI, and LR) and recorded for analysis. CBCT data were acquired once every 5 fractions for a total of 5 images per patient. The images were all taken after the couch move but before treatment. A 3-dimensional (3D-3D) bony anatomy auto-match was performed offline and the residual difference in position recorded for analysis. The average ({+-} 1 SD) move required from skin marks, calculated over all 375 fractions (15 patients Multiplication-Sign 25 fractions/patient), were AP = -2.6 {+-} 3.7 mm, SI = -0.3 {+-} 4.9 mm, and LR = 1.8 {+-} 4.5 mm. The average residual difference in patient position calculated from the weekly CBCT data (75 total) were AP = -1.7 {+-} 0.4 mm, SI = 1.1 {+-} 0.6 mm, and LR = -0.5 {+-} 0.2 mm. These results show that the BB does provide simple patient positioning that is accurate to within {+-} 2.0 mm when using online orthogonal kV-kV image matching of the pelvic bony anatomy.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2013

Effect of MLC leaf position, collimator rotation angle, and gantry rotation angle errors on intensity-modulated radiotherapy plans for nasopharyngeal carcinoma

The purpose of this study was to investigate the effect of multileaf collimator (MLC) leaf position, collimator rotation angle, and accelerator gantry rotation angle errors on intensity-modulated radiotherapy plans for nasopharyngeal carcinoma. To compare dosimetric differences between the simulating plans and the clinical plans with evaluation parameters, 6 patients with nasopharyngeal carcinoma were selected for simulation of systematic and random MLC leaf position errors, collimator rotation angle errors, and accelerator gantry rotation angle errors. There was a high sensitivity to dose distribution for systematic MLC leaf position errors in response to field size. When the systematic MLC position errors were 0.5, 1, and 2 mm, respectively, the maximum values of the mean dose deviation, observed in parotid glands, were 4.63%, 8.69%, and 18.32%, respectively. The dosimetric effect was comparatively small for systematic MLC shift errors. For random MLC errors up to 2 mm and collimator and gantry rotation angle errors up to 0.5°, the dosimetric effect was negligible. We suggest that quality control be regularly conducted for MLC leaves, so as to ensure that systematic MLC leaf position errors are within 0.5 mm. Because the dosimetric effect of 0.5° collimator and gantry rotation angle errors is negligible, it can be concluded that setting a proper threshold for allowed errors of collimator and gantry rotation angle may increase treatment efficacy and reduce treatment time.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2024

Bifurcation of equilibrium positions for ellipsoidal particles in inertial shear flows between two walls

We conducted a systematic numerical investigation of spherical, prolate and oblate particles in an inertial shear flow between two parallel walls, using smoothed particle hydrodynamics (SPH). It was previously shown that above a critical Reynolds number, spherical particles experience a supercritical pitchfork bifurcation of the equilibrium position in shear flow between two parallel walls, namely that the central equilibrium position becomes unstable, leading to the emergence of two new off-centre stable positions (Foxet al.,J. Fluid Mech., vol. 915, 2021). This phenomenon was unexpected given the symmetry of the system. In addition to confirming this finding, we found, surprisingly, that ellipsoidal particles can also return to the centre position from the off-centre positions when the particle Reynolds number is further increased, while spherical particles become unstable under this increased Reynolds number. By utilizing both SPH and the finite element method for flow visualization, we explained the underlining mechanism of this reverse of bifurcation by altered streamwise vorticity and symmetry breaking of pressure. Furthermore, we expanded our investigation to include asymmetric particles, a novel aspect that had not been previously modelled, and we observed similar trends in particle dynamics for both symmetric and asymmetric ellipsoidal particles. While further validation through laboratory experiments is necessary, our research paves the road for development of new focusing and separation methods for shaped particles.

Mechanics↗
DOE OSTI2015

Identifying Important Ions and Positions in Mass Spectrometry Imaging Data Using CUR Matrix Decompositions

Mass spectrometry imaging enables label-free, high-resolution spatial mapping of the chemical composition of complex, biological samples. Typical experiments require selecting ions and/or positions from the images: ions for fragmentation studies to identify keystone compounds and positions for follow up validation measurements using microdissection or other orthogonal techniques. Unfortunately, with modern imaging machines, these must be selected from an overwhelming amount of raw data. Existing techniques to reduce the volume of data, the most popular of which are principle component analysis and non-negative matrix factorization, have the disadvantage that they return difficult-to-interpret linear combinations of actual data elements. In this work, we show that CX and CUR matrix decompositions can be used directly to address this selection need. CX and CUR matrix decompositions use empirical statistical leverage scores of the input data to provide provably good low-rank approximations of the measured data that are expressed in terms of actual ions and actual positions, as opposed to difficult-to-interpret eigenions and eigenpositions. We show that this leads to effective prioritization of information for both ions and positions. In particular, important ions can be found either by using the leverage scores as a ranking function and using a deterministic greedy selection algorithm or by using the leverage scores as an importance sampling distribution and using a random sampling algorithm; however, selection of important positions from the original matrix performed significantly better when they were chosen with the random sampling algorithm. Also, we show that 20 ions or 40 locations can be used to reconstruct the original matrix to a tolerance of 17% error for a widely studied image of brain lipids; and we provide a scalable implementation of this method that is applicable for analysis of the raw data where there are often more than a million rows and/or columns, which is larger than SVD-based low-rank approximation methods can handle. Lastly, these results introduce the concept of CX/CUR matrix factorizations to mass spectrometry imaging, describing their utility and illustrating principled algorithmic approaches to deal with the overwhelming amount of data generated by modern mass spectrometry imaging.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Thermal processing to modulate surface chemistry and bulk charge distribution in nickel-rich layered lithium positive electrodes

The broader application of nickel-rich layered oxides as positive electrode materials for lithium-ion batteries has been hindered by their high manufacturing cost and inferior cycling stability. Thermal processing, which is integral to electrode materials manufacturing and fundamental in materials science, has not been fully utilized to design advanced positive electrode materials. Herein, we demonstrate the capability of using quenching heat treatment to regulate Li distribution and modulate electronic structure near particle surface. The resulting materials exhibit less parasitic reactions with the electrolyte and an improved charge distribution homogeneity in secondary particles, leading to more stable cycling performance at high voltages (4.5 V vs Li/Li + ). Our synchrotron X-ray analyses reveal the underlying interplay between surface structure and bulk charge distribution in positive electrode materials particles. While strategies used to stabilize positive electrode materials through compositional control, surface modification, and electrolyte engineering have become mature, thermal processing can be advantageous to further improve positive electrode materials manufacturing.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Solvation effects on the band edge positions of photocatalysts from first principles

The band edge positions of photocatalysts relative to the redox potentials of water play an important role in determining the efficiency of photoelectrochemical cells. These band positions depend on the structure of the solid–liquid interface, but direct ab initio molecular dynamics calculations of these interfaces, while expected to be accurate, are too computationally demanding for high-throughput materials screening. Thus rapid theoretical screening of new photocatalyst materials requires simplified continuum solvation models that are suitable for treating solid–liquid interfaces. In this paper, we evaluate the accuracy of the recently developed CANDLE and SaLSA continuum solvation models for predicting solvation effects on the band positions of several well-studied surfaces [Si(111), TiO 2 (110), IrO 2 (110) and WO 3 (001)] in water. We find that the solvation effects vary considerably, ranging from <0.5 eV for hydrophobic surfaces, 0.5–1 eV for many hydrophilic oxide surfaces, to ~2 eV for oxygen-deficient surfaces. The solvation model predictions are in excellent agreement (within ~0.1 eV) with ab initio molecular dynamics results where available, and in good agreement (within ~0.2–0.3 eV) with experimental measurements. We also predict the energetics for surface oxygen vacancies and their effect on the band positions of the hydrated WO 3 (001) surface, leading to an explanation for why the solvation shift observed experimentally is substantially larger than predicted for the ideal surface. Finally, based on the correlation between solvation shift and the type of surface and solvent, we suggest approaches to engineer the band positions of surfaces in aqueous and non-aqueous solutions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗