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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 793 records · Page 44
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Interferon-α and cyclooxygenase-2 inhibitor cooperatively mediates TRAIL-induced apoptosis in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related mortality worldwide. Interferon-alpha (IFN-α) has recently been recognized to harbor therapeutic potential in the prevention and treatment of HCC, but it remains controversial as to whether IFN-α exerts direct cytotoxicity against HCC. Cyclooxygenase-2 (COX-2) is overexpressed in HCC and is considered to play a role in hepatocarcinogenesis. Therefore, we aimed to elucidate the combined effect of a COX-2 inhibitor, celecoxib, and IFN-α on in vitro growth suppression of HCC using the hepatoma cell line HLCZ01 and the in vivo nude mouse xenotransplantation model using HLCZ01 cells. Treatment with celecoxib and IFN-α synergistically inhibited cell proliferation in a dose- and time-dependent manner. Apoptosis was identified by 4',6-diamidino-2-phenylindole dihydrochloride and fluorescent staining. IFN-α upregulated the expression of TRAIL, while celecoxib increased the expression of TRAIL receptors. The combined regimen with celecoxib and IFN-α reduced the growth of xenotransplanted HCCs in nude mice. The regulation of IFN-α- and COX-2 inhibitor-induced cell death is impaired in a subset of TRAIL-resistant cells. The molecular mechanisms of HCC cells resistant to TRAIL-induced apoptosis were explored using molecular biological and immunological methods. Interferon-α and the COX-2 inhibitor celecoxib synergistically increased TRAIL-induced apoptosis in hepatocellular carcinoma. These data suggest that IFN-α and celecoxib may offer a novel role with important implications in designing new therapeutics for TRAIL-resistant tumors. - Highlights: ●The cytotoxic effect of TRAIL on a developed HCC HLCZ01 cells infected with HBV. ●IFN-α and celecoxib induced apoptosis in HLCZ01 cells infected with HBV. ●The combined regime reduced the growth of xenotransplanted HCCs in nude mice model.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

NF-κB and neutrophil extracellular traps cooperate to promote breast cancer progression and metastasis

Highlights: • Cancer cells–derived factors, such as IL-8 and G-CSF, induce NETs formation via PAD4 and NF-κB. • NETs increase the interaction of NEMO with IKKα/β and enhance NF-κB activation. • Blockade of NETs using PAD4 inhibitor decreases NF-κB and tumor metastasis. • Selective inhibition of NF-κB reduces NETs formation and tumor growth and metastasis. Aberrant NF-κB activation and neutrophil extracellular traps (NETs) are associated with breast cancer progression. How NF-κB and NETs modulate each other in breast cancer development remains unclear. Here, we found that NETs induced by phorbol 12-myristate 13-acetate promote breast cancer cell progression. In turn, cancer cells–derived factors, such as IL-8 and granulocyte colony-stimulating factor, stimulate neutrophils to form NETs. Mechanistically, NETs increased the interaction of NF-κB essential modifier (NEMO) with IκB kinase (IKK)α/β and enhanced NF-κB activation. We then employed a cell-permeable peptide corresponding to the NEMO-binding domain (NBD) of IKKα/β, termed NBD peptide, which disrupts NETs-mediated NEMO interaction with IKKα/β and abolished NF-κB activation in vitro. NBD peptide also reduced IL-8 level and NETs formation, and suppressed primary tumor growth and/or lung metastasis in human breast cancer mouse xenograft models and mouse spontaneous breast cancer model. Blockade of NET formation using a peptidylarginine deiminase 4 (PAD4) pharmacologic inhibitor decreased NF-κB activation and tumor metastasis. Collectively, these data suggest that NF-κB associates with NETs to form a positive loop facilitating breast tumor progression and metastasis, and that selective inhibition of NF-κB and PAD4-dependent NETs provides an effective therapeutic approach for treating breast cancer.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2025

Advancing the Performance of Lithium-Rich Oxides in Cooperation with Inherent Complexities: Engineering Domain Structure

The nanodomain structure of lithium- and manganese-rich, composite cathode materials has been systematically altered through synthesis conditions while keeping larger-scale morphological differences to a minimum. Clear changes in electrochemical performance across the samples studied are observed, especially with respect to the anomalous impedance at low states-of-charge. Atomic-scale modeling, coupled to electrochemical measurements and physical characterization, reveals the local consequences of the high-voltage activation charge process as a function of specific domain structures. Furthermore, the results explain the influence of different postactivation structures on the insertion of Li-ions and the associated impedance during discharge. This work adds to our series of studies on lithium- and manganese-rich oxides, demonstrating that the inherent performance of LMRs can be greatly enhanced through rational, highly controlled synthetic strategies based on an understanding of synthesis–structure–property relationships across length scales.

25 ENERGY STORAGE↗
DOE OSTI2021

Comment on Improved CO 2 Hydrogenation on Ni–ZnO/MCM-41 Catalysts with Cooperative Ni and ZnO Sites

A recent publication from Murthy et al.1 describes experiments in which they proposed the hypothesis that a bifunctional catalyst consisting of adlineated,2 nanometer-sized domains of Ni and ZnO, confined within the pores of MCM-41, hydrogenates carbon dioxide adsorbed on the ZnO using hydrogen atoms produced by the Ni-catalyzed dissociation of H2. The reanalysis of their data presented below suggests that the reaction rates they employed to test their hypothesis, when properly normalized, show little to no effect of bifunctionality. This closer inspection of their data raises the possibility that the observed effects may instead arise from experimental artifacts (e.g., different levels of conversion, finite rates of mass transport) or morphological correlations that were not considered by the authors.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Coordination-Induced Weakening of N–H Bonds Driven by Bimetallic Cooperativity in Zr/Co Compounds

The bond dissociation free energy (BDFE) of the element-hydrogen bonds of protic substrates have been found to decrease upon metal coordination. Herein, an early/late heterobimetallic complex is used to examine the impact on the BDFE N−H when the substrate binding site and the redox-active site are two different metals that are spatially separated. A tris- (phosphinoamide) framework is used to link a d 0 ZrIV center with an accessible substrate binding site to a coordinatively saturated redox-active Co center, which serves as an appended electron reservoir. A series of aniline, amido, and imido Zr/Co model compounds were synthesized starting from the Zr IV /Co −I aniline adduct PhH 2 N−Zr(MesNP i Pr 2 ) 3 CoCN t Bu (2). 2,4,6-tristert- butylphenoxyl radical ( t Bu 3 ArO • ) was used to abstract one or two H atoms and produce the amido and imido complexes PhHNZr( MesNP i Pr 2 ) 3 CoCN t Bu (3) and PhN≡Zr(MesNP i Pr 2 ) 3 CoCNtBu (4), respectively. Using open-circuit potential measurements, the BDFE N−H within 2 and 3 were determined to be 37 kcal/mol (2) and 55 kcal/mol (3). Cyclic voltammetry measurements were conducted to determine the Co I/0 and Co 0/−I redox potentials. The pK a s were then estimated using the Bordwell equation to provide further insight into the thermochemical aspects of the observed proton coupled electron transfer (PCET) reactions.

Bond dissociation free energy↗
DOE OSTI2016

Cooperative Electronic and Structural Regulation in a Bioinspired Allosteric Photoredox Catalyst

Here in this article, we report the first allosteric photoredox catalyst regulated via constructively coupled structural and electronic control. While often synergistically exploited in nature, these two types of control mechanisms have only been applied independently in the vast majority of allosteric enzyme mimics and receptors in the literature. By embedding a model of photosystem II in a supramolecular coordination complex that responds to chloride as an allosteric effector, we show that distance and electronic control of light harvesting can be married to maximize allosteric regulation of catalytic activity. This biomimetic system is composed of a Bodipy photoantenna, which is capable of transferring excited-state energy to a photoredox pair, wherein the excitation energy is used to generate a catalytically active charge-separated state. The structural aspect of allosteric regulation is achieved by toggling the coordination chemistry of an antenna-functionalized hemilabile ligand via partial displacement from a Rh I structual node using chloride. In doing so, the distance between the antenna and the central photoredox catalyst is increased, lowering the inherent efficiency of through-space energy transfer. At the same time, coordination of chloride lowers both the charge of the Rh I node and the reduction potential of the Rh II/I couple, to the extent that electronic quenching of the antenna excited state is possible via photoinduced electron transfer from the metal center. Compared to a previously developed system that operates solely via electronic regulation, the present system demonstrates that coupling electronic and structural approaches to allosteric regulation gives rise to improved switching ratios between catalytically active and inactive states. Contributions from both structural and electronic control mechanisms are probed via nuclear magnetic resonance, X-ray diffraction, electrochemical, spectroelectrochemical, and transient absorption studies. Overall, this work establishes that intertwined electronic and structural regulatory mechanisms can be borrowed from nature to build stimuli-responsive inorganic materials with potential applications in sensing, catalysis, and photonic devices.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Synthesis, Crystal Structure, and Cooperative 3d–5d Magnetism in Rock Salt Type Li 4 NiOsO 6 and Li 3 Ni 2 OsO 6

Two new transition metal oxides with the nominal chemical compositions of Li 4 NiOsO 6 and Li 3 Ni 2 OsO 6 were successfully synthesized. Both compounds crystallize in an ordered rock salt structure type in the monoclinic C2/m space group. The crystal structures were determined using both synchrotron X-ray and time-of-flight neutron, powder diffraction data. In both phases, Ni2+ ions are present while oxidation states of osmium are +6 and +5 in Li 4 NiOsO 6 and Li 3 Ni 2 OsO 6 , respectively. Ni2+ ions in the hypothetical fully ordered phase form a honeycomb arrangement in the ab crystallographic plane and these hexagons are centered by osmium ions. Furthermore, the magnetic layers are separated along the c axis by the octahedra, which are centered by Li+ (or Li+/Ni 2+ , depending on the chemical compositions). Crystal structure refinements reveal that there is some degree of mixed occupancy in cationic positions. Temperature dependent magnetic susceptibility data for both phases show ferrimagnetic transitions with predominant antiferromagnetic (AFM) interactions among 3d electrons of nickel and Sd electrons of osmium. Iso-thermal magnetization loops as a function of the applied magnetic field below the transition temperatures confirm the ferrimagnetic nature in magnetic transitions. Temperature dependent heat capacity data, however, did not exhibit any anomaly in either phase, indicating the absence of long-range magnetic ordering. The lack of long-range order for both Os 5+ and Os 6+ -based compounds was also confirmed by low temperature neutron diffraction data down to 10 K. Temperature dependent AC magnetic susceptibility data in various frequencies for both samples indicate that Li 4 NiOsO 6 exhibits spin-glass-like behavior, while the transition temperature for Li 3 Ni 2 OsO 6 is nearly frequency independent.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗