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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Inferring pesticide toxicity to honey bees from a field‐based feeding study using a colony model and Bayesian inference

Abstract Honey bees are crucial pollinators for agricultural crops but are threatened by a multitude of stressors including exposure to pesticides. Linking our understanding of how pesticides affect individual bees to colony‐level responses is challenging because colonies show emergent properties based on complex internal processes and interactions among individual bees. Agent‐based models that simulate honey bee colony dynamics may be a tool for scaling between individual and colony effects of a pesticide. The U.S. Environmental Protection Agency (USEPA) and U.S. Department of Agriculture (USDA) are developing the VarroaPop + Pesticide model, which simulates the dynamics of honey bee colonies and how they respond to multiple stressors, including weather, Varroa mites, and pesticides. To evaluate this model, we used Approximate Bayesian Computation to fit field data from an empirical study where honey bee colonies were fed the insecticide clothianidin. This allowed us to reproduce colony feeding study data by simulating colony demography and mortality from ingestion of contaminated food. We found that VarroaPop + Pesticide was able to fit general trends in colony population size and structure and reproduce colony declines from increasing clothianidin exposure. The model underestimated adverse effects at low exposure (36 µg/kg), however, and overestimated recovery at the highest exposure level (140 µg/kg), for the adult and pupa endpoints, suggesting that mechanisms besides oral toxicity‐induced mortality may have played a role in colony declines. The VarroaPop + Pesticide model estimates an adult oral LD 50 of 18.9 ng/bee (95% CI 10.1–32.6) based on the simulated feeding study data, which falls just above the 95% confidence intervals of values observed in laboratory toxicology studies on individual bees. Overall, our results demonstrate a novel method for analyzing colony‐level data on pesticide effects on bees and making inferences on pesticide toxicity to individual bees.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2014

The potential of ill-nitride laser diodes for solid-state lighting [Advantages of III-Nitride Laser Diodes in Solid-State Lighting]

III-nitride laser diodes (LDs) are an interesting light source for solid-state lighting (SSL). Modelling of LDs is performed to reveal the potential advantages over traditionally used light-emitting diodes (LEDs). The first, and most notable, advantage is LDs have higher efficiency at higher currents when compared to LEDs. This is because Auger recombination that causes efficiency droop can no longer grow after laser threshold. Second, the same phosphor-converted methods used with LEDs can also be used with LDs to produce white light with similar color rendering and color temperature. Third, producing white light from direct emitters is equally challenging for both LEDs and LDs, with neither source having a direct advantage. Lastly, the LD emission is directional and can be more readily captured and focused, leading to the possibility of novel and more compact luminaires. These advantages make LDs a compelling source for future SSL.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Unveiling the Dynamics of KRAS4b on Lipid Model Membranes

Abstract Small GTPase proteins are ubiquitous and responsible for regulating several processes related to cell growth and differentiation. Mutations that stabilize their active state can lead to uncontrolled cell proliferation and cancer. Although these proteins are well characterized at the cellular scale, the molecular mechanisms governing their functions are still poorly understood. In addition, there is limited information about the regulatory function of the cell membrane which supports their activity. Thus, we have studied the dynamics and conformations of the farnesylated KRAS4b in various membrane model systems, ranging from binary fluid mixtures to heterogeneous raft mimics. Our approach combines long time-scale coarse-grained (CG) simulations and Markov state models to dissect the membrane-supported dynamics of KRAS4b. Our simulations reveal that protein dynamics is mainly modulated by the presence of anionic lipids and to some extent by the nucleotide state (activation) of the protein. In addition, our results suggest that both the farnesyl and the polybasic hypervariable region (HVR) are responsible for its preferential partitioning within the liquid-disordered (Ld) domains in membranes, potentially enhancing the formation of membrane-driven signaling platforms. Graphic Abstract

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2018

Excess Conductivity Investigation of Y{sub 3}Ba{sub 5}Cu{sub 8}O{sub 18±δ} Superconductors Prepared by Various Parameters of Planetary Ball Milling Technique

Superconducting samples of type Y{sub 3}Ba{sub 5}Cu{sub 8}O{sub 18±δ} were elaborated by using a planetary high-energy ball milling (HEBM) technique with various parameters. Phases, microstructure, and superconductivity have been examined using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and electrical resistivity measurements. SEM investigation shows the occurrence of nanoentities embedded into the superconducting matrix for samples prepared by a ball milling technique. The main objective of this study is to investigate the influence of ball milling parameters on the fluctuation-induced conductivity (FIC). The electrical resistivity versus temperature, ρ(T), above T{sub c} was analyzed using Lawrence–Doniach (LD) and Aslamazov–Larkin (AL) models. Different fluctuation regimes indicated by short-wave fluctuation (SWF) and three-dimensional (3D), two-dimensional (2D), one-dimensional (1D), and critical region (CR) fluctuations were identified. The coherence length at zero temperature, the effective layer thickness, the critical magnetic fields, and the critical current densities are determined. The superconducting parameters strongly depend on the planetary ball milling technique, and the results are explained in relevancy to the microstructure. It was found that the achievement of a microstructure with well-dispersed nanoentities is an effective way for introducing pinning centers for enhancing critical current density and flux pinning capability of bulk Y-358.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

Characterizing the flux effect on the irradiation embrittlement of reactor pressure vessel steels using machine learning

In-service exposure to high-energy neutrons embrittles reactor pressure vessel (RPV) steels. An increase in the yield stress (Δσ y ) results in a corresponding increase in the brittle to ductile transition temperature (ΔT c ). Most existing models underpredict ΔT c at higher fluence following accelerated irradiations in test reactors. High fluence, up to 10 20 n/cm 2 in some cases, will be reached over extended RPV vessel operation of 80 years, or more, at low service flux. Embrittlement has been extensively studied in accelerated, higher flux test reaction irradiations. However, the use of test reactor data naturally raises the question of flux effects. Here, this study used a machine learning approach trained on a set of hardening data, covering a wide range of flux, fluence, and steel compositions to determine the interactive effects of both irradiation and material variables on Δσ y . The analysis included machine learning-based cross-plots of the variable dependence of Δσ y for six core steels (i.e., CM6, LC, LD, LG, LH, and LI), with controlled differences in their Cu and Ni contents. A primary objective is to evaluate an effective to actual fluence (Φt e /Φt) ratio, as a function of flux, fluence, and steel composition. This is information critical to properly use intermediate flux-high fluence data in calibrating a low flux-high fluence embrittlement model. The predicted Φt e /Φt is reasonably consistent with estimates previously derived from a physics-based solute recombination trap model.

36 MATERIALS SCIENCE↗
DOE OSTI2015

New synthetic peptide with efficacy for heparin reversal and low toxicity and immunogenicity in comparison to protamine sulfate

Protamine sulfate (PS), the only clinically approved antidote to unfractionated heparin (UFH), is widely used for cardiopulmonary surgery or other extracorporeal circulation situations. However, the applications of PS have accompanied various severe side-effects. In this study, we presented a novel synthesized peptide compound (RRRRR-RRRRR-RRRRR-sulfate, R15S) served as a safer UFH antidote. Comparison studies were conducted between PS and R15S on efficacy and safety, aided by heparin neutralization studies, drug toxicity studies and anaphylactic analysis. Our research demonstrated that R15S contained comparable UFH neutralization activity in vitro and in rats in vivo as to active partial thromboplastin time (APTT) and anti-FXa assays. There was no cytotoxicity for R15S at 60 μg mg{sup −1} or below and the median lethal dose (LD{sub 50}) of R15S in mice was 35.4 mg kg{sup −1}, both of which were similar to that of PS. Furthermore, R15S exhibited no immunogenicity while it was obvious in guinea pigs immunized with PS. The level of cross-reactivity to anti-PS antibodies of R15S was about 30%. Both of which indicated much safer properties of R15S than PS. In conclusion, we presented a promising candidate R15S for UFH reversal, which is effective in neutralizing UFH and potentially safer in use. - Highlights: • R15 sulfate has a comparable unfractionated heparin neutralization activity to PS. • R15 sulfate avoided severe anaphylactic responses which happened to PS in clinical use. • R15 sulfate could provide a stricter quality control compared to PS which may vary with different batches.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Molecular cloning, genomic organization, chromosome mapping, tissues expression pattern and identification of a novel splicing variant of porcine CIDEb gene

Cell death-inducing DNA fragmentation factor-α-like effector b (CIDEb) is a member of the CIDE family of apoptosis-inducing factors, CIDEa and CIDEc have been reported to be Lipid droplets (LDs)-associated proteins that promote atypical LD fusion in adipocytes, and responsible for liver steatosis under fasting and obese conditions, whereas CIDEb promotes lipid storage under normal diet conditions [1], and promotes the formation of triacylglyceride-enriched VLDL particles in hepatocytes [2]. Here, we report the gene cloning, chromosome mapping, tissue distribution, genetic expression analysis, and identification of a novel splicing variant of the porcine CIDEb gene. Sequence analysis shows that the open reading frame of the normal porcine CIDEb isoform covers 660bp and encodes a 219-amino acid polypeptide, whereas its alternative splicing variant encodes a 142-amino acid polypeptide truncated at the fourth exon and comprised of the CIDE-N domain and part of the CIDE-C domain. The deduced amino acid sequence of normal porcine CIDEb shows an 85.8% similarity to the human protein and 80.0% to the mouse protein. The CIDEb genomic sequence spans approximately 6KB comprised of five exons and four introns. Radiation hybrid mapping demonstrated that porcine CIDEb is located at chromosome 7q21 and at a distance of 57cR from the most significantly linked marker, S0334, regions that are syntenic with the corresponding region in the human genome. Tissue expression analysis indicated that normal CIDEb mRNA is ubiquitously expressed in many porcine tissues. It was highly expressed in white adipose tissue and was observed at relatively high levels in the liver, lung, small intestine, lymphatic tissue and brain. The normal version of CIDEb was the predominant form in all tested tissues, whereas the splicing variant was expressed at low levels in all examined tissues except the lymphatic tissue. Furthermore, genetic expression analysis indicated that CIDEb mRNA levels were significantly higher in the white adipose tissue of lean pigs than their obese counterparts, in contrast to porcine CIDEa and CIDEc [3]. We therefore speculate that CIDEb may play a contrary role to the other CIDEs. The basic molecular information we provide here will be useful for further investigations of the physiological function of the gene, which will be helpful in better understanding the role of the CIDE family in lipid metabolism in pig models.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Dihydroceramide is a key metabolite that regulates autophagy and promotes fibrosis in hepatic steatosis model

Highlights: • FFA uptake increases sphingolipids in liver cells. • Dihydroceramide product correlates with autophagosome accumulation. • Dihydroceramide impairs autophagic flux and increases lipid droplets. • Rapamycin recuperates fibrosis by recovering autophagic flux by increased dihydroceramide. Non-alcoholic fatty liver disease (NAFLD) is an increasingly common chronic liver disease worldwide. Sphingolipids are a family of lipids that play essential roles as critical regulators in metabolic disorders. Some sphingolipids are known key factors in metabolic dysfunction. However, the precise effect of dihydroceramide on NAFLD remains unknown. Here, we report how dihydroceramide in autophagosome accumulation activates fibrogenesis in human liver Chang cells treated with free fatty acids (FFA). According to LC/MS lipid profiling, FFA increased the levels of sphingolipids and triacylglycerol (TG). To demonstrate the potential role of dihydroceramide metabolism in autophagy, several sphingolipid synthesis inhibitors were used. Increased dihydroceramide led to impairment of autophagic flux, resulting in increased TG storage in lipid droplets (LD) and upregulated expression of fibrosis markers. Hepatic stellate cells (HSCs, LX-2 cells) were co-cultured with Chang cells to assess the potential fibrogenic response to dihydroceramide, Treatment with rapamycin recovered autophagic flux in Chang cells and fibrogenesis in the co-culture system. Our results identified a critical function of dihydroceramide metabolism in autophagy. It could play an important role in the progression of NAFLD associated with lipid over-accumulation. Therefore, preventing autophagic flux by regulating dihydroceramide could be a potential strategic approach for providing therapy for NAFLD.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Light exposure influences the diurnal oscillation of gut microbiota in mice

Highlights: • Gut microbiota displayed robust rhythmic fluctuation in both compositional and functional level in mice. • The fluctuation of gut microbiota was modulated by enviromental light exposure. • The abundance of Clostridiawas dramatically enhanced in the small intestine when mice were underwent constant darkness. The gut microbiota exhibit diurnal compositional and functional oscillations that influence the host homeostasis. However, the upstream factors that affect the microbial oscillations remain elusive. Here, we focused on the potential impact of light exposure, the main factor that affects the host circadian oscillation, on the diurnal oscillations of intestinal microflora to explore the upstream factor that governs the fluctuations of the gut microbes. The gut microbiota of the mice that were underwent regular light/dark (LD) cycles exhibited a robust rhythm at both compositional and functional level, in all parts of the intestine. Comparably, constant darkness (Dark-Dark, DD) led to the loss of the rhythmic oscillations in almost all parts of the intestine. Additionally, the abundance of Clostridia in DD conditions was dramatically enhanced in the small intestine. Our data indicated light exposure is the upstream factor that governs the regular diurnal fluctuations of gut microbiota in vivo.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Alleviation of A disintegrin and metalloprotease 10 (ADAM10) on thromboangiitis obliterans involves the HMGB1/RAGE/ NF-κB pathway

Highlights: • TAO rats displayed higher whole blood viscosity and blood platelet count. • TAO rats had structural damages of vascular smooth muscle and endothelial cells. • ADAM treatment alleviated the symptoms of TAO rats in a dose-dependent pattern. • HMGB1, RAGE and NF-κB increased in TAO rats in both mRNA and protein level. • HMGB1, RAGE and NF-κB decreased by ADAM10 treatment in both mRNA and protein level. Thromboangiitis obliterans (TAO), also known as Buerger's disease, is a nonatherosclerotic inflammatory disease that influences medium- and small-sized blood vessels of extremities. However, mechanisms underlying TAO are still unclear. As a mediator associated with inflammation, A disintegrin and metalloprotease 10 (ADAM10) was hypothesized to play inhibitory roles in the development of TAO. Thus, the objective of this study is to investigate the effects of ADAM10 in a sodium laurate-induced TAO rat model and elucidate underlying mechanisms. Male Wistar rats were randomly divided into four groups (n = 6) for treatment: sham-operated (SHAM), TAO model (TAO), ADAM10 low dose injection (3 mg/kg; ADAM10-LD) and ADAM10 high dose injection (6 mg/kg; ADAM10-HD). After 14-day treatment, color Doppler ultrasound and hematology analysis indicated TAO rats displayed higher whole blood viscosity and blood platelet count compared with those in the SHAM group. Histologic evaluation and transmission electron microscopy revealed that the ultrastructural damages of vascular smooth muscle and endothelial cells were observed in TAO rats, such as fractured endoplasmic reticulum, decreased cell counts, and fibrillation. On the other hand, the typical signs and symptoms of TAO rats were significantly alleviated via ADAM10 treatment with a dose-dependent pattern. Real-time PCR and western blot results revealed that the expression of high-mobility-group box 1 (HMGB1), receptor for advanced glycation end-products (RAGE) and nuclear factor-kappa B (NF-κB) increased in TAO rats whereas decreased by ADAM10 treatment in both mRNA and protein levels. In conclusion, the results suggest ADAM10 alleviates symptoms of sodium laurate-induced TAO in rats via the RAGE/NF-κB signaling pathway and provides insight into the molecular basis and a potential therapeutic strategy for TAO.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Effect of the hydration temperature on the pore structure of cement paste: Experimental investigation and micromechanical modelling

The hydration temperature has a considerable effect on the microstructure of cement paste. The microstructural changes with increasing curing temperature result in a significant decrease of cement mechanical properties. The present work aims at studying these phenomena via micromechanical modelling, based on an experimental characterization of cement microstructure. The pore structure of a class G oil-well cement paste (American Petroleum Institute classification) hydrated at different temperatures, between 7 °C and 90 °C is characterized. Then, the influence of the microstructure variations on the elastic properties of the hardened paste is explored through micromechanical modelling. A previous analysis of the microstructure enabled determining the volume fractions of different phases of a class G cement paste hydrated under different temperatures [1]. A multiscale self-consistent homogenization model is used based on these results to simulate the variations of the mechanical properties with hydration temperature. The results are compared with macro-scale elastic properties obtained from uniaxial compression tests. It is shown that the increasing capillary porosity with elevating hydration temperature, is not sufficient to fully explain this drop of elastic properties. The latter originates mainly from the decrease of the elastic properties of the foam composed of the porous C-S-H intermixed with capillary pores. The pore structure analysis coupled with the micromechanical modelling permitted a back-analysis of the intrinsic porosities of high density and low density C-S-H showing an almost constant LD intrinsic porosity and a significantly decreasing HD intrinsic porosity.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Microstructural and micromechanical characteristics of ultra-high performance concrete with superabsorbent polymer (SAP)

In this study, the hydration product, C-S-H density, and pore structure at different layers from the drying surface were measured. Besides, the zone affected by the released internal curing water from SAP was identified by assessing the nanoindentation modulus. The results found that the SAP affected the moisture distribution and changed the evaporation and self-desiccation rates in the inner and outer layers. Such imposed moisture gradients affected the micromechanical properties of UHPC at different layers due to the change in the hydration degree of the binder, the density of C-S-H, and the pore structure of the matrix. The addition of SAP improved the hydration dynamics and transferred the LD C-S-H into HD or UHD C-S-H. As the distance from the drying surface increased, the affected zone of SAP increased from 60 to 120 μm, showing the more effectiveness of SAP at inner layers.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Machine learning-enhanced MPC for demand flexibility in small commercial buildings: An experimental study

Small- and medium-sized commercial buildings (SMCBs) represent the majority of U.S. commercial building stock and a significant share of peak electricity demand, yet they often lack centralized building automation systems, representing a significant untapped resource for urban energy management. This infrastructure gap makes advanced control implementation challenging, limiting the potential for widespread demand flexibility. Model Predictive Control (MPC) has shown strong potential for load shifting, peak demand reduction, and cost savings, but its effectiveness is hindered by unmeasured disturbances such as internal heat gains. This paper presents a Hybrid MPC framework that integrates a physics-based gray-box building thermal model, identified using a lumped disturbance (LD) approach, with a machine learning (ML) model for forecasting unmeasured disturbances. The hybrid approach is designed for buildings with multiple individually controlled heat pump and thermostat pairs, common in SMCBs, and aims to optimize coordinated scheduling of multiple heat pumps under dynamic electricity pricing while respecting comfort constraints. The methodology is validated through both simulations of case study buildings and experimental studies at a highly-instrumented test facility. Simulation results show that the Hybrid MPC achieves substantial load shifting and peak demand reduction, approaching the performance of an ideal MPC with perfect disturbance knowledge, and outperforming a conventional MPC without disturbance forecasting. In experiments, the Hybrid MPC reduced daily HVAC energy costs by 8.7%, peak-price time load (load shifting) by 41.7%, and peak demand by 29.2% compared to baseline control, demonstrating comparable benefits to the 11.6% cost savings, 42.9% load shifting, and 23.2% peak reduction of the ideal MPC. These results demonstrate that the proposed hybrid modeling approach can significantly improve MPC performance in real-world SMCB applications without requiring additional disturbance measurements.

Demand Flexibility↗
DOE OSTI2018

Combined effects of microplastics and chemical contaminants on the organ toxicity of zebrafish (Danio rerio)

Highlights: • Microplastics did not produce effects on gene expression in zebrafish after 3 weeks. • Microplastics and sorbed chemicals had a greater effect than chemicals alone. • Effects were detected mainly in the liver. • Perfluorinated compounds were detected mainly in the liver. • Adverse effect of microplastics and sorbed chemicals should be considered in risk assessment. Microplastics contamination of the aquatic environment is considered a growing problem. The ingestion of microplastics has been documented for a variety of aquatic animals. Studies have shown the potential of microplastics to affect the bioavailability and uptake route of sorbed co-contaminants of different nature in living organisms. Persistent organic pollutants and metals have been the co-contaminants majorly investigated in this field. The combined effect of microplastics and sorbed co-contaminants in aquatic organisms still needs to be properly understood. To address this, we have subjected zebrafish to four different feeds: A) untreated feed; B) feed supplemented with microplastics (LD-PE 125–250 µm of diameter); C) feed supplemented with 2% microplastics to which a mixture of PCBs, BFRs, PFCs and methylmercury were sorbed; and D) feed supplemented with the mixture of contaminants only. After 3 weeks of exposure fish were dissected and liver, intestine, muscular tissue and brain were extracted. After visual observation, evaluation of differential gene expression of some selected biomarker genes in liver, intestine and brain were carried out. Additionally, quantification of perfluorinated compounds in liver, brain, muscular tissue and intestine of some selected samples were performed. The feed supplemented with microplastics with sorbed contaminants produced the most evident effects especially on the liver. The results indicate that microplastics alone does not produce relevant effects on zebrafish in the experimental conditions tested; on the contrary, the combined effect of microplastics and sorbed contaminants altered significantly their organs homeostasis in a greater manner than the contaminants alone.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Energy transfer and 2.0 μm emission in Tm{sup 3+}/Ho{sup 3+} co-doped α-NaYF{sub 4} single crystals

Highlights: • Cubic NaYF{sub 4} single crystals co-doped with ∼1.90 mol% Tm{sup 3+} and various Ho{sup 3+} concentrations were grown by Bridgman method. • The maximum fluorescence lifetime was 23.23 ms for Tm{sup 3+} (1.90 mol%)/Ho{sup 3+} (3.89 mol%) co-doped α-NaYF{sub 4}. • The obtained energy transfer rate (W{sub ET}) and energy transfer efficiency (η) of Tm{sup 3+}:{sup 3}F{sub 4} are 1077 s{sup −1} and 95.0%, respectively. • The maximum emission cross section reached 1.06 × 10{sup −20} cm{sup 2}. - Abstract: Cubic NaYF{sub 4} single crystals co-doped with ∼1.90 mol% Tm{sup 3+} and various Ho{sup 3+} concentrations were grown by Bridgman method. The energy transfer from Tm{sup 3+} to Ho{sup 3+} and the optimum fluorescence emission around 2.04 μm of Ho{sup 3+} ion were investigated based on the measured absorption spectra, emission spectra, emission cross section and decay curves under excitation of 800 nm LD. The emission intensity at 2.04 μm increased with the increase of Ho{sup 3+} concentration from 0.96 mol% to 3.89 mol% when the concentration of Tm{sup 3+} was held constantly at ∼1.90 mol%. Moreover, the maximum emission cross section reached 1.06 × 10{sup −20} cm{sup 2} and the maximum fluorescence lifetime was 23.23 ms for Tm{sup 3+}(1.90 mol%)/Ho{sup 3+}(3.89 mol%) co-doped one. According to the measured lifetime of Tm{sup 3+} single-doped and Tm{sup 3+}/Ho{sup 3+} co-doped samples, the maximum energy transfer efficiency of Tm{sup 3+}:{sup 3}F{sub 4} level was 95.0%. Analysis on the fluorescence dynamics indicated that electric dipole–dipole is dominant for the energy transfer from Tm{sup 3+} to Ho{sup 3+}.

36 MATERIALS SCIENCE↗