Search NASA⌕ Search

SEARCH · Search NASA

Results for “SOR”

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

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

15 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Sorafenib derivatives-functionalized gold nanoparticles confer protection against tumor angiogenesis and proliferation via suppression of EGFR and VEGFR-2

Sorafenib is a multi-kinase inhibitor that has been highlighted as a tumor suppressor due to its anti-proliferative and anti-angiogenic properties, whereas the clinical application of Sorafenib is restricted by the side effects it may cause. The past decade has witnessed the development of a series of sorafenib derivatives to improve the clinical performance of sorafenib. Gold nanoparticles (AuNPs) have been widely utilized in drug delivery systems due to their unique properties, including biocompatible nature, simple preparation, and easy surface modification. Herein, this study is aimed to investigate the anti-tumor effects of new sorafenib derivatives-capped gold nanoparticles (AuNPs-New Sor) in tumor formation and metastasis as well as the underlying mechanisms. Initially, new sorafenib derivatives were constructed and combined with AuNPs to form AuNPs-New Sor, and the properties of synthesized AuNPs-New Sor were identified in a mouse model of tumorigenesis. The effect of AuNPs-New Sor on tumor vascular normalization was investigated by assessing vascular permeability and perfusion rate. Next, we evaluated the effect of AuNPs-New Sor on migration and viability of tumor cells and human umbilical vein endothelial cells (HUVECs) as well as on HUVEC angiogenesis in vitro. A melanoma mouse model was further established for in vivo substantiation of the anti-tumor effect of AuNPs-New Sor. According to the results, AuNPs could deliver new sorafenib derivatives into tumor tissues and downregulate the expression of epidermal growth factor receptor (EGFR) and vascular endothelial growth factor receptor-2 (VEGFR-2), thereby suppressing tumor migration, EMT, and angiogenesis in vitro. In addition, AuNPs-New Sor displayed competitive anti-tumor activities in vivo. Taken together, AuNPs-New Sor may attenuate tumor development and angiogenesis through downregulation of EGFR and VEGFR-2.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2020

Sorption, solubility and cytotoxicity of novel antibacterial nanofilled dental adhesive resins

Dental adhesives hydrolyze in the mouth. This study investigated the water sorption (SOR), solubility (SOL) and cytotoxicity (CYTO) of experimental adhesives containing nitrogen-doped titanium dioxide nanoparticles (N_TiO 2 ). Specimens (n = 15/group [SOR, SOL]; n = 10/group [CYTO]) of unaltered Clearfil SE Protect (CSP), OptiBond Solo Plus (OSP), Adper Scotchbond (ASB) and experimental adhesives (OSP + 25% or 30% of N_TiO 2 ) were fabricated, desiccated (37 °C) and tested for SOR and SOL according to ISO Specification 4049 (2009). CYTO specimens were UV-sterilized (8 J/cm 2 ) and monomer extracted in growth medium (1, 3 or 7 days). Human pulp cells were isolated and seeded (0.5 × 10 4 ) for MTT assay. SOR and SOL data was analyzed using GLM and SNK (α = 0.05) and CYTO data was analyzed with Kruskal–Wallis and SNK tests (α = 0.05). SOR and SOL values ranged from 25.80 μg/mm 3 (30% N_TiO 2 ) to 28.01 μg/mm 3 (OSP) and 23.88 μg/mm 3 (30% N_TiO 2 ) to 25.39 μg/mm 3 (25% N_TiO 2 ). CYTO results indicated that pulp cells exposed to experimental materials displayed comparable viabilities (p > 0.05) to those of OSP. Experimental materials displayed comparable SOR, SOL and CYTO values (p > 0.05) when compared to unaltered materials. N_TiO 2 incorporation have not adversely impacted SOR, SOL and CYTO properties of unaltered adhesives.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2020

The antibiotic sorangicin A inhibits promoter DNA unwinding in a Mycobacterium tuberculosis rifampicin-resistant RNA polymerase

Rifampicin (Rif) is a first-line therapeutic used to treat the infectious disease tuberculosis (TB), which is caused by the pathogen Mycobacterium tuberculosis (Mtb). The emergence of Rif-resistant (Rif R ) Mtb presents a need for new antibiotics. Rif targets the enzyme RNA polymerase (RNAP). Sorangicin A (Sor) is an unrelated inhibitor that binds in the Rif-binding pocket of RNAP. Sor inhibits a subset of Rif R RNAPs, including the most prevalent clinical Rif R RNAP substitution found in Mtb infected patients (S456>L of the β subunit). In this paper, we present structural and biochemical data demonstrating that Sor inhibits the wild-type Mtb RNAP by a similar mechanism as Rif: by preventing the translocation of very short RNAs. By contrast, Sor inhibits the RifR S456L enzyme at an earlier step, preventing the transition of a partially unwound promoter DNA intermediate to the fully opened DNA and blocking the template-strand DNA from reaching the active site in the RNAP catalytic center. By defining template-strand blocking as a mechanism for inhibition, we provide a mechanistic drug target in RNAP. Our finding that Sor inhibits the wild-type and mutant RNAPs through different mechanisms prompts future considerations for designing antibiotics against resistant targets. Also, we show that Sor has a better pharmacokinetic profile than Rif, making it a suitable starting molecule to design drugs to be used for the treatment of TB patients with comorbidities who require multiple medications.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Breaking the passivation barrier via d-p orbital optimization for stable hydrogen production and sulfion upgrading

The development of energy-efficient hydrogen production technologies represents a critical pathway toward achieving global carbon neutrality objectives. This work provides fundamental insights into overcoming catalyst passivation challenges in sulfide oxidation reaction (SOR)-coupled hydrogen evolution reaction (HER) systems through precise orbital hybridization engineering. Our theoretical simulations reveal that sulfur-passivated ruthenium surfaces can effectively modulate d-p orbital hybridization, significantly reduce d-electron activity while stabilizing long-chain S 8 species and decreasing intermediate adsorption energies. Furthermore, metal carbides/ruthenium heterostructure (MC/Ru, M = V, Mo, W) was designed to achieve simultaneous optimization of both HER (∆G H* = −0.11 eV) and SOR (∆G RDS = 1.51 eV) via work-function-mediated interfacial electron transfer, which effectively tailors surface electronic states. Guided by theoretical predictions, we successfully synthesized a series of metal carbides/ruthenium/nitrogen-doped carbon catalysts based on a solid-phase reaction and designated as MC/Ru@NC (M = V, Mo, W). The optimized VC/Ru@NC catalyst exhibits exceptional performance in a membrane-free two-electrode system, achieving an ultralow cell voltage of 0.76 V at 200 mA cm −2 with outstanding stability over 1600 h, while maintaining 97.5 % Faradaic efficiency for hydrogen production and 73.8 % sulfur recovery efficiency.

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

Trichloroethylene replacements for the cleaning of silicone oil used in the internal gelation process

Silicone oil continues to be used as a gelation medium for internal gelation process. Typically, the silicone oil has been removed from the gel spheres using trichloroethylene (TCE) washes. However, TCE is no longer a viable option for large-scale operations because of environmental issues, health concerns, and disposal costs. Furthermore, during the development of a large gelation system at the Y-12 National Security Complex, two new TCE wash replacements were identified. NuSolv SOR-C and FluoSolv WS were used in a number of uranium runs and found to effectively remove silicone oil. NuSolv SOR-C was determined to be the best option.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Enhancing Heavy-Oil-Recovery Efficiency by Combining Low-Salinity-Water and Polymer Flooding

Summary Combining low-salinity-water (LSW) and polymer flooding was proposed to unlock the tremendous heavy-oil resources on the Alaska North Slope (ANS). The synergy of LSW and polymer flooding was demonstrated through coreflooding experiments at various conditions. The results indicate that the high-salinity polymer (HSP) (salinity = 27,500 ppm) requires nearly two-thirds more polymer than the low-salinity polymer (LSP) (salinity = 2,500 ppm) to achieve the target viscosity at the condition of this study. Additional oil was recovered from LSW flooding after extensive high-salinity-water (HSW) flooding [3 to 9% of original oil in place (OOIP)]. LSW flooding performed in secondary mode achieved higher recovery than that in tertiary mode. Also, the occurrence of water breakthrough can be delayed in the LSW flooding compared with the HSW flooding. Strikingly, after extensive LSW flooding and HSP flooding, incremental oil recovery (approximately 8% of OOIP) was still achieved by LSP flooding with the same viscosity as the HSP. The pH increase of the effluent during LSW/LSP flooding was significantly greater than that during HSW/HSP flooding, indicating the presence of the low-salinity effect (LSE). The residual-oil-saturation (Sor) reduction induced by the LSE in the area unswept during the LSW flooding (mainly smaller pores) would contribute to the increased oil recovery. LSP flooding performed directly after waterflooding recovered more incremental oil (approximately 10% of OOIP) compared with HSP flooding performed in the same scheme. Apart from the improved sweep efficiency by polymer, the low-salinity-induced Sor reduction also would contribute to the increased oil recovery by the LSP. A nearly 2-year pilot test in the Milne Point Field on the ANS has shown impressive success of the proposed hybrid enhanced-oil-recovery (EOR) process: water-cut reduction (70 to less than 15%), increasing oil rate, and no polymer breakthrough so far. This work has demonstrated the remarkable economical and technical benefits of combining LSW and polymer flooding in enhancing heavy-oil recovery.

Engineering↗
DOE OSTI2024

GPU Acceleration of a Diagnostic Wind Solver

Reducing QUIC-Fire simulation runtimes is crucial in enabling simulation ensembles to guide science-driven prescribed fire planning in regions of complex terrain. Utilizing GPUs through OpenACC and Kokkos frameworks to accelerate generation of 3D windfields in QUIC-Fire would provide substantial speedup to the runtime of the code. Using GPUs for the Successive Over-Relaxation (SOR) algorithm utilized in QUIC-Fire will require deriving a ‘four colored’ version of the well explored ‘Red-Black’ SOR parallelization scheme. This effort could open the door for utilizing GPUs in other portions of the QUIC-Fire algorithm, increasing its viability in more complex and larger domains.

58 GEOSCIENCES↗
DOE OSTI2021

Biodiesel from oil produced in vegetative tissues of biomass – A review

Biodiesel is a green, renewable alternative to petroleum-derived diesel. However, using vegetable oil for bio- diesel production significantly challenges the food security. Progress in metabolic engineering, understanding of lipid biosynthesis and storage have enabled engineering of vegetative tissues of plants such as sugarcane, sor- ghum, and tobacco for lipid production. Such sources could be cultivated on land resources, which are currently not suitable for row crops. Besides achieving significant lipid accumulation, it is imperative to maintain the fatty acid and lipid profile ideal for biodiesel production and engine performance. In this study, genetic modifications used to induce lipid accumulation in transgenic crops and the proposed strategies for efficient recovery of oil from these crops have been presented. Here, this paper highlights that lipids sourced from vegetative biomass in their native form would pose significant challenges in biodiesel production. Therefore, different strategies have been presented for improving feedstock quality to achieve high-quality biodiesel production.

09 BIOMASS FUELS↗
DOE OSTI2022

Automated Vehicle Multi-Object Tracking at Scale with CAN

Millions of vehicles are on the road with RADAR sensors in use for adaptive cruise control (ACC), and RADAR sen- sors are not tracking all of the objects in the field of view. This work shows a work-in-progress tool to improve track- ing from RADAR and controller area network (CAN) which should be vitally useful for safety of transportation systems and automated vehicle development. The CAN data provides object detections, but there is a lingering data association problem. The contribution of this work in progress is the solution to the data association problem by posing the data association as a minimum cost network flow problem, and doing it at low cost with an eye toward scalable CPS research.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2022

Optical O 2 Sensors Also Respond to Redox Active Molecules Commonly Secreted by Bacteria

From a metabolic perspective, molecular oxygen (O 2 ) is arguably the most significant constituent of Earth’s atmosphere. Nearly every facet of microbial physiology is sensitive to the presence and concentration of O 2 , which is the most favorable terminal electron acceptor used by organisms and also a dangerously reactive oxidant. As O 2 has such sweeping implications for physiology, researchers have developed diverse approaches to measure O 2 concentrations in natural and laboratory settings. Recent improvements to phosphorescent O 2 sensors piqued our interest due to the promise of optical measurement of spatiotemporal O 2 dynamics. However, we found that our preferred bacterial model, Pseudomonas aeruginosa PA14, secretes more than one molecule that quenches such sen sors, complicating O 2 measurements in PA14 cultures and biofilms. Assaying supernatants from cultures of 9 bacterial species demonstrated that this phenotype is common: all super natants quenched a soluble O 2 probe substantially. Phosphorescent O 2 probes are often embedded in solid support for protection, but an embedded probe called O 2 NS was quenched by most supernatants as well. Measurements using pure compounds indicated that quenching is due to interactions with redox-active small molecules, including phena zines and flavins. Uncharged and weakly polar molecules like pyocyanin were especially potent quenchers of O 2 NS. These findings underscore that optical O 2 measurements made in the presence of bacteria should be carefully controlled to ensure that O 2 , and not bacterial secretions, is measured, and motivate the design of custom O 2 probes for specific organisms to circumvent sensitivity to redox-active metabolites.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Polymer Retention Evaluation in a Heavy Oil Sand for a Polymer Flooding Application on Alaska’s North Slope

For a polymer flooding field trial in a heavy oil reservoir on Alaska’s North Slope, polymer retention is a key parameter. Because of the economic impact of retention, this parameter was extensively studied using field core material and conditions. Several important findings were noted. Polymer retention based on effluent viscosity measurements can be overestimated unless the correct (non-linear) relation between polymer concentration and viscosity is used. Polymer degradation (either mechanical or oxidative) can also lead viscosity-based measurements to overestimate retention. Inaccessible pore volume (IAPV) can be overestimated if insufficient brine is flushed through the sand between polymer banks. Around 100 pore volumes (PV) of brine may be needed to displace mobile polymer to approach a true residual resistance factor and properly measure IAPV. Even for a sand pack with kwsor = 20 mD, IAPV was zero for HPAM with molecular weight (Mw) of 18 million g/mol. Fine-grain particles (<20 μm) strongly impacted polymer retention values. Native NB#1 sand with a significant component of particles <20 μm exhibited 290 μg/g, while the same sand exhibited 28 μg/g after these small particles were removed. Polymer retention did not necessarily correlate with mineral composition. The NB#1, NB#3, and OA sands had similar elemental and clay compositions, but the NB#1 sand exhibited ~10 times higher retention than the NB#3 sand. Polymer retention did not necessarily correlate with permeability. NB#1 sand exhibited much higher retention than OA sand, even though NB#1 sand was twice as permeable as OA sand. No evidence of chromatographic separation of HPAM molecular weights was found in our experiments. Although retention tended to be greater without a residual oil saturation (than at Sor), the effect was not strong. Aging a core (with high oil saturation) at 60°C reduced HPAM retention by a factor of two. As expected, under similar conditions, polymer retention was greater for a higher Mw HPAM (18 million g/mol) than for a lower Mw HPAM (10-12 million g/mol). In many cases with high polymer retention values (e.g., 240 μg/g), polymer arrival at the end of the core was relatively quick, but achieving the injected concentration occurred gradually over many pore volumes. This effect was not due chromatographic separation of polymer molecular weights. Results from modeling of this behavior was consistent with concentrationdependent polymer retention. The form assumed for the retention function in a simulator can have an important impact on the timing and magnitude of the oil response from a polymer flood. Field-based observations can underestimate polymer retention, depending on when the tracer and polymer concentrations were measured and the assumptions made about reservoir heterogeneity.

Wang, Dongmei↗
DOE OSTI2023

Thin‐Film Organic Heteroepitaxy

Abstract Incorporating crystalline organic semiconductors into electronic devices requires understanding of heteroepitaxy given the ubiquity of heterojunctions in these devices. However, while rules for commensurate epitaxy of covalent or ionic inorganic material systems are known to be dictated by lattice matching constraints, rules for heteroepitaxy of molecular systems are still being written. Here, it is found that lattice matching alone is insufficient to achieve heteroepitaxy in molecular systems, owing to weak intermolecular forces that describe molecular crystals. It is found that, in addition, the lattice matched plane also must be the lowest energy surface of the adcrystal to achieve one‐to‐one commensurate molecular heteroepitaxy over a large area. Ultraviolet photoelectron spectroscopy demonstrates the lattice matched interface to be of higher electronic quality than a disordered interface of the same materials.

36 MATERIALS SCIENCE↗