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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 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Influence of Welding Strength Matching Coefficient and Cold Stretching on Welding Residual Stress in Austenitic Stainless Steel

Austenitic stainless steel is widely used in pressure vessels for the storage and transportation of liquid gases such as liquid nitrogen, liquid oxygen, and liquid hydrogen. Cryogenic pressure vessel manufacturing uses cold stretching technology, which relies heavily on welding joint performance, to construct lightweight and thin-walled vessels. Residual stress from welding is a primary factor in cases of austenitic stainless steel pressure vessel failure. In this paper, on the basis of Visual Environment 10.0 finite element simulation technology, the residual stress resulting from different welding strength matching coefficients (0.8, 1, 1.2, 1.4) for two S30408 plates welded with three-pass butt welds is calculated according to thermal elastoplastic theory. In addition, the stress field was calculated under a loading as high as 410 MPa and after the load was released. Path 1 was set to analyze stress along the welding line, and path 2 was set to analyze stress normal to the welding line. The welding strength matching coefficient strongly affected both the longitudinal residual stress (center of path 1) and the transverse residual stress (both ends of path 1) after the welding was completed. However, the coefficient had little effect on the longitudinal and transverse residual stress of path 2. Under the loading of 410 MPa, the longitudinal and transverse stress decreased and the stress distribution, with different welding strength matching coefficients, was less diverse. After the load was released, longitudinal and transverse stress distribution for both path 1 and path 2 decreased to a low level. Cold stretching could reduce the effect of residual stress to various degrees. Transverse strain along the stretching direction was also taken into consideration. The experimental results validated the reliability of the partial simulation.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Coupling of organic and inorganic aerosol systems and the effect on gas–particle partitioning in the southeastern US

Abstract. Several models were used to describe the partitioning of ammonia, water, and organic compounds between the gas and particle phases for conditions in the southeastern US during summer 2013. Existing equilibrium models and frameworks were found to be sufficient, although additional improvements in terms of estimating pure-species vapor pressures are needed. Thermodynamic model predictions were consistent, to first order, with a molar ratio of ammonium to sulfate of approximately 1.6 to 1.8 (ratio of ammonium to 2 × sulfate, R N/2S ≈ 0.8 to 0.9) with approximately 70 % of total ammonia and ammonium (NH x ) in the particle. Southeastern Aerosol Research and Characterization Network (SEARCH) gas and aerosol and Southern Oxidant and Aerosol Study (SOAS) Monitor for AeRosols and Gases in Ambient air (MARGA) aerosol measurements were consistent with these conditions. CMAQv5.2 regional chemical transport model predictions did not reflect these conditions due to a factor of 3 overestimate of the nonvolatile cations. In addition, gas-phase ammonia was overestimated in the CMAQ model leading to an even lower fraction of total ammonia in the particle. Chemical Speciation Network (CSN) and aerosol mass spectrometer (AMS) measurements indicated less ammonium per sulfate than SEARCH and MARGA measurements and were inconsistent with thermodynamic model predictions. Organic compounds were predicted to be present to some extent in the same phase as inorganic constituents, modifying their activity and resulting in a decrease in [H + ] air (H + in µg m -3 air), increase in ammonia partitioning to the gas phase, and increase in pH compared to complete organic vs. inorganic liquid–liquid phase separation. In addition, accounting for nonideal mixing modified the pH such that a fully interactive inorganic–organic system had a pH roughly 0.7 units higher than predicted using traditional methods (pH = 1.5 vs. 0.7). Particle-phase interactions of organic and inorganic compounds were found to increase partitioning towards the particle phase (vs. gas phase) for highly oxygenated (O : C ≥ 0.6) compounds including several isoprene-derived tracers as well as levoglucosan but decrease particle-phase partitioning for low O : C, monoterpene-derived species.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Manganese Oxidation during Vegetation Burning

Redox recycling of manganese (Mn) plays a key role in organic matter decomposition and nutrient cycling in terrestrial vegetated ecosystems, and it is expected to be changed by fires. This study revealed how Mn is oxidized during vegetation burning, by characterizing the chemical speciation of Mn in fire ash from wildland fires and laboratory burning and evaluating the factors governing its average oxidation state (AOS) and speciation. Manganese in wildland fire ash from different ecosystems showed variable AOS that ranges from 2.5 to 3.3. Laboratory burning experiments showed that Mn oxidation was primarily controlled by fire thermal intensity (temperature × duration) and burning completeness. As heating time increased from 5 min to 5 h at 550 and 700 °C, Mn AOS in the lab-burned vegetation ash increased from 2.7 to 4.0 and the oxidation rate was faster at higher temperature. Diverse Mn species can present in wildland fire ash and differ structurally from biogenic Mn oxides. The oxidized Mn species enable fire ash to mediate oxidative degradation of catechol, demonstrating its potential in mediating organic matter decomposition. This study revealed a new paradigm of Mn redox recycling, as compared to the microbe-mediated Mn redox cycling in the absence of fires.

36 MATERIALS SCIENCE↗
NASA NTRS2015

Cellular Response to Bleomycin-Induced DNA Damage in Human Fibroblast Cells in Space

Living organisms are constantly exposed to space radiation that consists of energetic protons and other heavier charged particles. Whether spaceflight factors, microgravity in particular, affects on the cellular response to DNA damage induced by exposures to radiation or other toxic chemicals will have an impact on the radiation risks for the astronauts, as well as on the mutation rate in microorganisms, is still an open question. Although the possible synergistic effects of space radiation and other spaceflight factors have been investigated since the early days of the human space program, the published results were mostly conflicting and inconsistent. To investigate the effects of spaceflight on the cellular response to DNA damages, human fibroblast cells flown to the International Space Station (ISS) were treated with bleomycin for three hours in the true microgravity environment, which induces DNA damages including the double strand breaks (DSB) similar to the ionizing radiation. Damage in the DNA was measured by the phosphorylation of a histone protein H2AX (-H2AX), which showed slightly more foci in the cells on ISS than in the ground control. The expression of genes involved in the DNA damage response was also analyzed using the PCR array. Although a number of the genes, including CDKN1A and PCNA, were significantly altered in the cells after bleomycin treatment, no significant difference in the expression profile of DNA damage response genes was found between the flight and ground samples. At the time of the bleomycin treatment, the cells on the ISS were found to be proliferating faster than the ground control as measured by the percentage of cells containing positive Ti-67 signals. Our results suggested that the difference in -H2AX between flight and ground was due to the faster growth rate of the cells in space, but spaceflight did not affect the response of the DNA damage response genes to bleomycin treatment.

Lu, Tao↗
DOE OSTI2017

A Peculiar GRB 110731A: Lorentz Factor, Jet Composition, Central Engine, and Progenitor

The jet compositions, central engines, and progenitors of gamma-ray bursts (GRBs) remain open questions in GRB physics. Applying broadband observations, including GRB prompt emission and afterglow properties derived from Fermi and Swift data, as well as from Keck host-galaxy observations, we address these questions for the peculiar, bright GRB 110731A. By using the pair-opacity method, we derive Γ{sub 0} > 190 during the prompt emission phase. Alternatively, we derive Γ{sub 0} ≈ 580 and Γ{sub 0} ≈ 154 by invoking the early-afterglow phase within the homogeneous density and wind cases, respectively. On the other hand, nondetection of a thermal component in the spectra suggests that the prompt emission is likely powered by dissipation of a Poynting-flux-dominated jet leading to synchrotron radiation in an optically thin region. The nondetection of a jet break in the X-ray and optical bands allows us to place a lower limit on the jet opening angle θ {sub j} > 5.°5. Within a millisecond magnetar central engine scenario, we derive the period P {sub 0} and polar magnetic field strength B {sub p}, which have extreme (but still allowed) values. The moderately short observed duration (7.3 s) and relatively large redshift (z = 2.83) place the burst as a “rest-frame short” GRB, so the progenitor of the burst is subject to debate. Its relatively large f{sub eff,z} parameter (ratio of the 1 s peak flux of a pseudo-GRB and the background flux) and a large physical offset from a potential host galaxy suggest that the progenitor of GRB 110731A may be a compact-star merger.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2015

Cellular Response to Bleomycin-Induced DNA Damage in Human Fibroblast Cells in Space

Outside the protection of the geomagnetic field, astronauts and other living organisms are constantly exposed to space radiation that consists of energetic protons and other heavier charged particles. Whether spaceflight factors, microgravity in particular, have effects on cellular responses to DNA damage induced by exposure to radiation or cytotoxic chemicals is still unknown, as is their impact on the radiation risks for astronauts and on the mutation rate in microorganisms. Although possible synergistic effects of space radiation and other spaceflight factors have been investigated since the early days of the human space program, the published results were mostly conflicting and inconsistent. To investigate effects of spaceflight on cellular responses to DNA damages, human fibroblast cells flown to the International Space Station (ISS) were treated with bleomycin for three hours in the true microgravity environment, which induced DNA damages including double-strand breaks (DSB) similar to the ionizing radiation. Damages in the DNA were measured by the phosphorylation of a histone protein H2AX (g-H2AX), which showed slightly more foci in the cells on ISS than in the ground control. The expression of genes involved in DNA damage response was also analyzed using the PCR array. Although a number of the genes, including CDKN1A and PCNA, were significantly altered in the cells after bleomycin treatment, no significant difference in the expression profile of DNA damage response genes was found between the flight and ground samples. At the time of the bleomycin treatment, the cells on the ISS were found to be proliferating faster than the ground control as measured by the percentage of cells containing positive Ki-67 signals. Our results suggested that the difference in g-H2AX focus counts between flight and ground was due to the faster growth rate of the cells in space, but spaceflight did not affect initial transcriptional responses of the DNA damage response genes to bleomycin treatment.

Lu, Tao↗
DOE OSTI2018

Elucidating Factors Controlling Long-Term Stability of Radical Anions for Negative Charge Storage in Nonaqueous Redox Flow Batteries

Radical anions of electrochemically reduced compounds (anolytes) have been suggested for storage of negative charge in nonaqueous redox flow batteries. The lower the redox potential of the anolyte molecule, the higher is the stored energy density. However, the stability of the radical ions frequently suffers as their redox potentials become extreme, and there is a compromise between the energy density and the chemical stability in the active form. In this paper, we scrutinize this trade-off using one such “extreme,” the heterocyclic anolyte 2,1,3-benzothiadiazole, BzNSN, by adjusting the redox potential of BzNSN via installed electron-donating and electron-withdrawing groups. We show that the stability of the radical anion strongly depends on the degree of ion pairing in solution, with the worst being for the contact lithium ion pairs. For BzNSN derivatives, there is a strong correlation between the lifetime of the radical anion and the redox potential. The root cause appears to be the proton transfer from the solvent (acetonitrile) to the radical anion, which is concerted with the dimerization of the solvent molecules. These interactions cause the radical anion to become unstable even though the redox couple falls well within the electrochemical stability window of the solvent. Steering this redox potential toward the middle of this window using electron-withdrawing groups did not pay off as it opened additional decomposition pathways. Finally, our study, therefore, suggests that there can be natural limitations to the energy density that is realistically achieved using neutral, closed-shell anolyte molecules for charge storage in the redox flow cells.

25 ENERGY STORAGE↗
DOE OSTI2018

Beneficial effects of paeoniflorin on osteoporosis induced by high-carbohydrate, high-fat diet-associated hyperlipidemia in vivo

Highlights: • Paeoniflorin significantly improved the serum lipid profile. • Paeoniflorin restored trabecular and cortical parameters, and the biomechanical strength. • Paeoniflorin reversed the hyperlipidemia associated-symptoms in the rat model. Osteoporosis is linked to reduced bone mineral density (BMD) as a major risk factor for fragility fractures. Recent studies indicated an association between BMD and abnormally elevated lipid levels in blood as common indicators for hyperlipidemia. In this study, we assessed the protective effect of paeoniflorin, a phytochemical compound with multiple pharmacological activities, against hyperlipidemia-induced osteoporosis in rats fed a high-carbohydrate, high-fat diet (HCHF). The special diet-fed rats were subjected to an 8-week treatment with either paeoniflorin (20 mg/kg, daily) or vehicle. The control group received a normal diet during the entire study. At study conclusion, serum markers of lipid metabolism and bone turnover were measured. Bone strength was assessed by biomechanical testing, and femurs were scanned using micro-computed tomography to analyze trabecular and cortical bone structure. Interestingly, paeoniflorin controlled the serum lipid profile by significantly decreasing HCHF-induced high levels of total cholesterol, triglyceride, and low-density lipoprotein cholesterol. Paeoniflorin significantly improved trabecular and cortical parameters as well as femur length and width that were negatively affected by HCHF diet. Biomechanical strength testing showed that femurs of HCHF diet-fed rats endured significantly lower force but higher displacement and strain than those of control rats, whereas paeoniflorin reversed the negative effects. Moreover, paeoniflorin rescued osteoblast differentiation and cell spreading activities along with bone turnover markers. In conclusion, HCHF-induced hyperlipidemia caused adverse effects on the bone that were rescued by paeoniflorin treatment.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2024

Interfacial Reactivity-Triggered Oscillatory Lattice Strains of Nanoalloys

Understanding the structure evolution of nanoalloys under reaction conditions is vital to the design of active and durable catalysts. Herein, we report an operando measurement of the dynamic lattice strains of dual-noble-metal alloyed with an earth-abundant metal as a model electrocatalyst in a working proton-exchange membrane fuel cell using synchrotron high-energy X-ray diffraction coupled with pair distribution function analysis. Additionally, the results reveal an interfacial reaction-triggered oscillatory lattice strain in the alloy nanoparticles upon surface dealloying. Analysis of the lattice strains with an apparent oscillatory irregularity in terms of frequency and amplitude using time-frequency domain transformation and theoretical calculation reveals its origin from a metal atom vacancy diffusion pathway to facilitate realloying upon dealloying. This process, coupled with surface metal partial oxidation, constitutes a key factor for the nanoalloy's durability under the electrocatalytic oxygen reduction reaction condition, which serves as a new guiding principle for engineering durable or self-healable electrocatalysts for sustainable fuel cell energy conversion.

Wu, Zhi-Peng [State University of New York (SUNY),↗
DOE OSTI2024

Measuring Impact: Evaluating Thermal Zoning Simplification on Energy Efficiency Measures Analysis

Building Energy Modeling (BEM) is a versatile tool for designing, retrofitting, ensuring code compliance, obtaining certifications, qualifying for incentives, and enabling real-time building control. However, capturing all the details of building geometry for thermal zoning can be time-consuming, costly, and sometimes computationally challenging. As a result, modelers have been applying zoning simplification based on factors such as space functions and internal loads, as well as relying on their experience and judgment while adhering to zoning rules outlined in industry standards. Despite the prevalence of this common practice, a notable gap exists in the literature regarding studies quantifying the influence of simplified thermal zoning on the evaluation of Energy Efficiency Measures (EEMs). Recognizing this gap, this paper seeks to contribute to the field by enhancing the understanding of how the simplification of thermal zoning influences the evaluation of EEMs against a baseline design. The study utilized a medium office prototype model with a detailed floor plan featuring over 20 zones per floor covering diverse functional spaces with varying internal loads and occupancy schedules. A standard thermal zoning strategy outlined in ASHRAE Standard 90.1 Appendix G was employed as the simplified zoning method. This strategy condenses the zoning into a core zone and four perimeter zones per floor. It was compared with the detailed zoning approach, which involves one zone per space. Common Energy EEMs, such as enhanced envelope, high-efficiency appliances and equipment, and HVAC controls, were individually implemented and evaluated. The results indicate that the performance comparison between the two zoning methods varies depending on the type of measures considered. Basic measures, such as adding wall insulation, demonstrate similar energy impacts, while advanced HVAC control measures, such as static pressure reset, exhibit a more substantial difference that cannot be overlooked.

Xie, Jiarong↗
DOE OSTI2025

DOME: Directional medical embedding vectors from Electronic Health Records

Motivation: The increasing availability of Electronic Health Record (EHR) systems has created enormous potential for translational research. Recent developments in representation learning techniques have led to effective large-scale representations of EHR concepts along with knowledge graphs that empower downstream EHR studies. However, most existing methods require training with patient-level data, limiting their abilities to expand the training with multi-institutional EHR data. On the other hand, scalable approaches that only require summary-level data do not incorporate temporal dependencies between concepts. Methods: We introduce a DirectiOnal Medical Embedding (DOME) algorithm to encode temporally directional relationships between medical concepts, using summary-level EHR data. Specifically, DOME first aggregates patient-level EHR data into an asymmetric co-occurrence matrix. Then it computes two Positive Pointwise Mutual Information (PPMI) matrices to correspondingly encode the pairwise prior and posterior dependencies between medical concepts. Following that, a joint matrix factorization is performed on the two PPMI matrices, which results in three vectors for each concept: a semantic embedding and two directional context embeddings. They collectively provide a comprehensive depiction of the temporal relationship between EHR concepts. Results: We highlight the advantages and translational potential of DOME through three sets of validation studies. First, DOME consistently improves existing direction-agnostic embedding vectors for disease risk prediction in several diseases, for example achieving a relative gain of 5.5% in the area under the receiver operating characteristic (AUROC) for lung cancer. Second, DOME excels in directional drug-disease relationship inference by successfully differentiating between drug side effects and indications, correspondingly achieving relative AUROC gain over the state-of-the-art methods by 10.8% and 6.6%. Finally, DOME effectively constructs directional knowledge graphs, which distinguish disease risk factors from comorbidities, thereby revealing disease progression trajectories. The source codes are provided at https://github.com/celehs/Directional-EHRembedding.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2023

Accelerating Scientific Simulations with Bi-Fidelity Weighted Transfer Learning

High-fidelity modeling is an essential design tool for many engineering applications. However, for complex systems, computational cost can be a limiting factor. Analyzing parameter sensitivity, uncertainty quantification, and design optimization require many model evaluations. Surrogate models are often used to develop the relationship between model parameters and quantities of interest. However, in the case of complex systems, surrogate models require several degrees of freedom and, thus, a large number of data points to determine the correct dependencies. For many applications, this may be prohibitively expensive. The reduction of computational requirements can be achieved by leveraging low-fidelity models. Low-fidelity models represent the system at a coarser resolution with the advantage of computational efficiency. Therefore, a bi-fidelity modeling paradigm, which augments the accuracy of a low-fidelity model in a computationally efficient manner by invoking limited runs of a high-fidelity model, can be leveraged to sufficiently balance the accuracy and computational requirements. In this work, a bi-fidelity weighted transfer learning method using neural networks was applied to a computational fluid dynamics heat transfer modeling problem. The transfer learning advantage was investigated as a function of hyperparameters. Our main finding is that the use of a bi-fidelity modeling paradigm achieves accuracy close to that of a high-fidelity Gaussian process model while significantly reducing computational cost. The bi-fidelity model achieves comparable performance with 90 high-fidelity samples-that is, 60% less than the samples needed to achieve similar accuracy without the use of bi-fidelity modeling,

Borowiec, Katarzyna↗
DOE OSTI2017

HTNV-induced upregulation of miR-146a in HUVECs promotes viral infection by modulating pro-inflammatory cytokine release

Increasing research has shown a link between viruses and miRNAs, such as miRNA-146a, in regulating virus infection and replication. In the current study, the association between miR-146a and hantaan virus (HTNV) infection in human umbilical vein endothelial cells (HUVECs) was investigated, with a focus on examining the expression of pro-inflammatory cytokines. The results showed that HTNV infection promoted the production of miR-146a in HUVECs and activated nuclear factor-κB (NF-κB) signaling, along with the upregulation of pro-inflammatory cytokines, including interleukin 8 (IL-8), C-C Motif Chemokine Ligand 5 (CCL5, also RANTES), interferon-inducible protein-10 (IP-10) and interferon beta (IFN-β). Moreover, miR-146a exhibited a negative regulatory effect on the NF-κB pathway. Accordingly, a miR-146a inhibitor increased the expression of IL-8, CCL5, IP-10 and IFN-β, whereas a miR-146a mimic reduced the levels of these cytokines. Consequently, exogenous transduction of miR-146a significantly enhanced HTNV replication in HUVEC cells. We also discovered that viral proteins (NP/GP) contributed to miR-146a expression via enhancement the activity of miR-146a promoter. In conclusion, these results imply the negative regulation of miR-146a on the production of HTNV-induced pro-inflammatory cytokines contributes to virus replication, which suggest that miR-146a may be regarded as a novel therapeutic target for HTNV infection. - Highlights: • Hantavirus infection increased miR-146a levels in HUVEC cells. • Hantavirus infection activated NF-κB signal and pro-inflammatory cytokines in HUVEC cells. • miR-146a had the negative regulation to NF-κBp65, IL-8, CCL5, IP-10, and IFN-β and promote the replication of hantavirus. • Expression of hantaviral proteins (NP/GP) stimulated the activity of miR-146a and NF-κB promoters.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

Coupled flow accumulation and atmospheric blocking govern flood duration

Abstract We present a physically based Bayesian network model for inference and prediction of flood duration that allows for a deeper understanding of the nexus of antecedent flow regime, atmospheric blocking, and moisture transport/release mechanisms. Distinct scaling factors at the land surface and regional atmospheric levels are unraveled using this Bayesian network model. Land surface scaling explains the variability in flood duration as a function of cumulative exceedance index, a new measure that represents the evolution of the flood in the basin. Dynamic atmospheric scaling explains the cumulative exceedance index using the interaction between atmospheric blocking system and the synergistic model of wind divergence and atmospheric water vapor. Our findings underline that the synergy between a large persistent low-pressure blocking system and a higher rate of divergent wind often triggers a long-duration flood, even in the presence of moderate moisture supply in the atmosphere. This condition in turn causes an extremely long-duration flood if the basin-wide cumulative flow prior to the flood event was already high. Thus, this new land-atmospheric interaction framework integrates regional flood duration scaling and dynamic atmospheric scaling to enable the coupling of ‘horizontal’ (for example, streamflow accumulation inside the basin) and ‘vertical’ flow of information (for example, interrelated land and ocean-atmosphere interactions), providing an improved understanding of the critical forcing of regional hydroclimatic systems. This Bayesian model approach is applied to the Missouri River Basin, which has the largest system of reservoirs in the United States. Our predictive model can aid in decision support systems for the protection of national infrastructure against long-duration flood events.

Najibi, Nasser (ORCID:0000000205157192)↗
DOE OSTI2019

Prognostic Role of the Immunoscore for Patients with Urothelial Carcinoma of the Bladder Who Underwent Radical Cystectomy

Background: Increasing evidence suggests that cancer progression is strongly influenced by the host immune response, which is represented by immune cell infiltrates. The T-lymphocyte-based Immunoscore is reported to be a reliable prognostic factor in colon cancer, but its significance in urothelial carcinoma of the bladder (UCB) is at an early stage of exploration. This study aimed to determine whether the tumor immune infiltrate, as evaluated by the Immunoscore, could act as a useful prognostic marker for UCB patients who have undergone radical cystectomy (RC). Methods: In this study, immunohistochemistry was used to examine the Immunoscore of 221 UCB patients who underwent RC. The Immunoscore of the patients was determined by the densities of CD3+ and CD8+ T cells at the tumor center and the invasive margin. Results: A highly significant association between a low Immunoscore and a shortened patient survival (P < 0.001, log-rank test) was demonstrated. In different subsets of UCB patients, a low Immunoscore also was a prognostic indicator of pT ≤ 2, pN(–)-status tumors, negative vascular invasion, or both (P < 0.05). Importantly, the Immunoscore together with the patient’s pT status provided significant independent prognostic parameters in the multivariate analysis (P < 0.05). Furthermore, a significant correlation (P = 0.003) of a low Immunoscore with an increased UCB labeling index of Ki-67 (a cell proliferation marker) was observed in this UCB cohort. Conclusions: The findings suggest that the Immunoscore, as examined by immunohistochemistry, might serve as a novel prognostic marker for UCB patients who have undergone RC.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

RBM17 controls apoptosis and proliferation to promote Glioma progression

Highlights: • RBM17 overexpressed in glioma patients and resulted in the poor prognosis. • Downregulation of RBM17 suppressed proliferation and induced apoptosis in glioma cells. • The silencing of RBM17 in U87 cells suppressed the tumor growth in vivo. • RBM17 on main signaling pathways in human glioma cells. The splicing factor SPF45 (RBM17) is a well-known component of the spliceosome that is involved in alternative splicing. RBM17 is frequently overexpressed in many tumors and plays a crucial role in cancer progression and drug resistance. However, the role of RBM17 in the development of glioma has not been thoroughly elucidated to date. In the present study, we found that RBM17 was overexpressed in glioma and that a high level of expression of RBM17 was closely associated with a poor prognosis in glioma patients. We investigated the effect of RBM17 on apoptosis, cell growth and cell cycle indexes and the activation of apoptosis signaling by shRNA in human U87 and U251 glioma cells. The downregulated expression of RBM17 mRNA was accompanied by the induction of cell cycle arrest, and apoptosis, reduced cell proliferation in the two cell lines, and reduced cell survival, as measured by the increased activation of caspase-3, caspase-9, and PARP (poly ADP-ribose polymerase). Furthermore, in subcutaneous U87 cell xenograft tumors in nude mice, intradermal administration of an shRNA targeting RBM17 significantly downregulated RBM17 expression in vivo and was accompanied by the suppressed growth of glioma. To the best of our knowledge, our results are the first to confirm that RBM17 functions in promoting cell proliferation, affecting the cell cycle, and inducing apoptosis in human glioma cells both in vitro and in vivo. These results indicate that RBM17 may be a therapeutic target in the clinical management of glioma.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2024

Large-scale simulation-based parametric analysis of an optimal precooling strategy for demand flexibility in a commercial office building

Achieving success with grid-interactive efficient buildings (GEBs) is closely tied to the utilization of flexible loads. A valuable strategy involves the implementation of precooling techniques before high-demand events, such as peak hours, by adjusting zone air temperature setpoints. This leads to a reduction in thermal loads and peak electricity demand during these times, as the building’s thermal mass stores and subsequently releases thermal energy. However, the effectiveness of the pre-cooling optimization is highly contingent on specific conditions such as building thermal properties, weather conditions, utility rate structure, HVAC equipment sizing, etc. Therefore, investigating the impacts of these condition-specific factors is crucial, especially when considering precooling strategies that utilize thermal mass in commercial buildings. In this paper, we first devised a novel heuristic control approach that incorporates parameterized optimal precooling thermostat schedules to enhance demand flexibility in a commercial office building. Subsequently, we conducted a thorough performance evaluation of this control strategy. Here, the optimal thermostat schedule was parameterized using three optimization variables: the precooling start time, the precooling end time, and the precooling temperature setpoint. Utilizing the DOE medium-sized office building as the virtual testbed, we showed that the parameterized schedule effectively approximates model predictive control and requires drastically reduced computational overhead. In addition, we investigated the impact of different influencing factors on the optimal precooling strategy. These factors include building thermal mass, outdoor air conditions, and energy price profiles. Using high-performance computing, we simulated a total of 225 scenarios, consisting of three levels of thermal mass, five typical outdoor air temperature profiles, and fifteen time-of-use price plans. The results demonstrate that optimal thermostat scheduling could save substantial energy cost in medium-sized office buildings with heavy thermal mass but with some energy penalty. Although the potential for cost savings is lower in buildings with low and medium thermal mass, the energy penalty remains consistent in all three thermal mass scenarios. The study also highlights the need to account for zone diversity and recognize that a one-size-fits-all-zone setpoint schedule may not be suitable for all zones and can lead to unnecessary energy wastage. Furthermore, the results highlight that while outdoor air conditions play a role in cost and energy performance, the cooling load exerts a more immediate and substantial influence on cost savings in precooling strategies. Although cost savings are comparable under certain conditions with the same cooling load, observed deviations in energy penalty indicate potential disparities in the efficiency of the HVAC system during the load-shifting process. In addition, the duration of peak pricing and the ratio between peak and off-peak times exhibit clear correlations with cost savings and energy consumption, aligning with intuitive expectations. These findings offer valuable insights for optimizing precooling strategies in office buildings.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2025

Aerosol hygroscopicity over the South-East Atlantic Ocean during the biomass burning season – Part 2: Influence of sea salt and burning conditions on CCN hygroscopicity

Biomass burning (BB) significantly influences cloud condensation nuclei (CCN) concentrations over the southeastern Atlantic; however, aerosol hygroscopicity (κ) – a key factor for CCN activation – remains poorly constrained during the BB season. This study investigates κ variability using in situ measurements from Ascension Island during the 2016 and 2017 BB seasons. Results show substantial monthly variability, with κ values lowest in August and increasing through October. On average, κ was significantly higher in 2017 (∼ 0.55) than in 2016 (∼ 0.33), suggesting that the aerosols in 2017 were more hygroscopic and more easily activated as CCN. Sulfate and sea salt were the two dominant contributors to κ and the primary drivers of its interannual variability. During the 2017 BB season, sulfate – the major inorganic component – accounted for ∼ 34 % of the submicron aerosol mass, while sea salt, estimated via κ-closure analysis, contributed ∼ 17 %. The higher κ in 2017 was largely attributed to increased sea salt, likely driven by stronger marine winds. Approximately 67 % of sulfate was linked to BB emissions. Variations in BB combustion efficiency, modulated by regional meteorology, influenced sulfate fraction and thus κ values. Specifically, higher relative humidity and lower wind speeds over BB source regions in 2017 favored smoldering combustion, explaining the higher sulfate fraction. Overall, the observed interannual differences in aerosol hygroscopicity reflect the combined impacts of BB combustion characteristics and sea salt emissions, underscoring the critical roles of both BB and marine aerosol sources in regulating aerosol-cloud interactions over the southeastern Atlantic.

54 ENVIRONMENTAL SCIENCES↗