Boosting Activity and Selectivity of CO2 Electroreduction by Pre-Hydridizing Pd Nanocubes
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99 GENERAL AND MISCELLANEOUS↗
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Boosting the activity of Fe-N[subscript x] moieties in Fe-N-C electrocatalysts via phosphorus doping for oxygen reduction reaction
Abstract not provided
Li, Jin-Cheng↗
Crowded supported metal atoms on catalytically active supports may compromise intrinsic activity: A case study of dual-site Pt/α-MoC catalysts
Increasing the surface population of supported catalytic sites, assuming these sites are stable, is considered a straightforward approach to improving the overall catalytic performance. Here, we report an exception represented by the Pt/α-MoC catalysts featuring atomically dispersed Pt. The Pt/α-MoC catalysts display very high activity for the reverse water gas shift reaction with near 100% CO selectivity for CO 2 :H 2 ratios from 0.25 to 4 and from 250 to 400 °C. Despite the excellent performance, the intrinsic activity per Pt-centric catalytic center declines as the Pt loading increases from 0.1 to 1.0 wt%. With the dispersed Pt evolving from isolated atoms to fully exposed ensembles, the shrinking inter-Pt-atom space impedes CO 2 activation at the critical Pt-Mo interfaces, where the Pt shall temporarily take the -O intermediates. The Pt, even as atomically dispersed without noticeable sintering, is underutilized in such a crowded state. This caution for high-loading catalyst design is translational to other systems where the direct catalytic roles of the supports are crucial.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Exchange proteins directly activated by cAMP induce the proliferation of rat anterior pituitary GH3 cells via the activation of extracellular signal-regulated kinase
Cyclic adenosine 3′-5’-monophosphate (cAMP) plays a crucial role in regulating pituitary cell proliferation and hormone synthesis. Recent evidence suggests that exchange proteins directly activated by cAMP (Epacs) may mediate the effects of cAMP. Here we used rat anterior pituitary GH3 cells as the experiment model to demonstrate that forskolin increased the proliferation of GH3 cells and the phosphorylation of ERK1/2, and these effects were inhibited by PKA or Epac inhibitors. Epac activator 8-pCPT-2′-O-Me-cAMP increased GH3 cell proliferation and this was blocked by ESI-09, an Epac inhibitor. In contrast, forskolin-induced phosphorylation of CREB was unaffected by Epac inhibition. Notably, increased phosphorylation of ERK1/2 was correlated with increased cyclin D3 expression in GH3 cells. Furthermore, knockdown of Epac as well as B-Raf and MEK inhibitors blocked 8-pCPT-2′-O-Me-cAMP induced proliferation of GH3 cells and the phosphorylation of ERK1/2. In conclusion, our study suggests that Epac mediates cAMP induced pituitary cell proliferation via B-Raf and MAPK dependent mechanism. - Highlights: • PKA and Epac mediate cAMP induced GH3 cell proliferation. • Activation or knockdown of Epac stimulates or inhibits GH3 cell proliferation. • Epac induces the phosphorylation of ERK1/2 in GH3 cells via B-Raf. • B-Raf and MEK inhibitors block cAMP induced GH3 cell proliferation.
60 APPLIED LIFE SCIENCES↗
Exosomes derived from pancreatic cancer cells induce activation and profibrogenic activities in pancreatic stellate cells
Highlights: • Effects of cancer cell-derived exosomes on stellate cell functions were examined. • Exosomes increased proliferation and migration in stellate cells. • Cancer cells increased miR-1246 and miR-1290 expression in stellate cells. • Exosomes and miR-1290 overexpression increased the expression of profibrogenic genes and ACTA2. • Exosome-mediated cell-to-cell communication regulates stellate cell functions. Pancreatic cancer cells (PCCs) interact with pancreatic stellate cells (PSCs), which play a pivotal role in pancreatic fibrogenesis, to develop the cancer-conditioned tumor microenvironment. Exosomes are membrane-enclosed nanovesicles, and have been increasingly recognized as important mediators of cell-to-cell communications. The aim of this study was to clarify the effects of PCC-derived exosomes on cell functions in PSCs. Exosomes were isolated from the conditioned medium of Panc-1 and SUIT-2 PCCs. Human primary PSCs were treated with PCC-derived exosomes. PCC-derived exosomes stimulated the proliferation, migration, activation of ERK and Akt, the mRNA expression of α-smooth muscle actin (ACTA2) and fibrosis-related genes, and procollagen type I C-peptide production in PSCs. Ingenuity pathway analysis of the microarray data identified transforming growth factor β1 and tumor necrosis factor as top upstream regulators. PCCs increased the expression of miR-1246 and miR-1290, abundantly contained in PCC-derived exosomes, in PSCs. Overexpression of miR-1290 induced the expression of ACTA2 and fibrosis-related genes in PSCs. In conclusion, PCC-derived exosomes stimulate activation and profibrogenic activities in PSCs. Exosome-mediated interactions between PSCs and PCCs might play a role in the development of the tumor microenvironment.
60 APPLIED LIFE SCIENCES↗
Cereblon deficiency confers resistance against polymicrobial sepsis by the activation of AMP activated protein kinase and heme-oxygenase-1
Cereblon (CRBN) has a pleiotropic role in important cellular processes and is a potential therapeutic target in several diseases, including mental retardation, cancer, and metabolic disorders. The role of CRBN in polymicrobial sepsis induced by cecal ligation and puncture (CLP) was investigated using CRBN-deficient (KO) mice. Survival following CLP was significantly higher in KO mice compared to wild-type (WT) controls (50% vs 0% at day 6 after CLP). The improved survival of KO mice was accompanied by reduced peripheral blood bacterial load and lung injury. Serum tumor necrosis factor (TNF)-α and high mobility group box 1 (HMGB1) concentrations were significantly lower in KO mice than in WT mice. Peritoneal macrophages from KO mice with CLP-induced septic mouse had higher levels of activation of AMPK and heme oxygenase-1 (HO-1). Forced expression of CRBN in macrophage of KO mice suppressed activation of 5′ adenosine monophosphate-activated protein kinase (AMPK) and HO-1 and augmented expression of TNF-α and HMGB1 as inhibition of AMPK by compound C. These studies demonstrate the contribution of CRBN expression to the pathogenesis of CLP-induced sepsis and peritoneal macrophage responses and suggest a novel therapeutic modality for polymicrobial sepsis.
60 APPLIED LIFE SCIENCES↗
Lack of O-GlcNAcylation enhances exercise-dependent glucose utilization potentially through AMP-activated protein kinase activation in skeletal muscle
Highlights: • Ogt deletion enhances exercise-dependent glucose utilization in skeletal muscle. • Ogt depletion enhances glucose uptake and oxidation in C2C12 myotubes. • Lack of O-GlcNAcylation increases AMPKα protein expression both in vivo and in vitro. • Ogt deletion in skeletal muscle reverses HFD-induced obesity and insulin resistance. O-GlcNAcylation is a post-translational modification that is characterized by the addition of N-acetylglucosamine (GlcNAc) to proteins by O-GlcNAc transferase (Ogt). The degree of O-GlcNAcylation is thought to be associated with glucotoxicity and diabetic complications, because GlcNAc is produced by a branch of the glycolytic pathway. However, its role in skeletal muscle has not been fully elucidated. In this study, we created skeletal muscle-specific Ogt knockout (Ogt-MKO) mice and analyzed their glucose metabolism. During an intraperitoneal glucose tolerance test, blood glucose was slightly lower in Ogt-MKO mice than in control Ogt-flox mice. High fat diet-induced obesity and insulin resistance were reversed in Ogt-MKO mice. In addition, 12-month-old Ogt-MKO mice had lower adipose and body mass. A single bout of exercise significantly reduced blood glucose in Ogt-MKO mice, probably because of higher AMP-activated protein kinase α (AMPKα) protein expression. Furthermore, intraperitoneal injection of 5-aminoimidazole-4-carboxamide ribonucleotide, an AMPK activator, resulted in a more marked decrease in blood glucose levels in Ogt-MKO mice than in controls. Finally, Ogt knockdown by siRNA in C2C12 myotubes significantly increased protein expression of AMPKα, glucose uptake and oxidation. In conclusion, loss of O-GlcNAcylation facilitates glucose utilization in skeletal muscle, potentially through AMPK activation. The inhibition of O-GlcNAcylation in skeletal muscle may have an anti-diabetic effect, through an enhancement of glucose utilization during exercise.
60 APPLIED LIFE SCIENCES↗
Enhanced chemical activity and wettability at adjacent Brønsted acid sites in HZSM-5
Not provided.
Chemistry↗
Investigation on a green olivine nano-silica source based activator in alkali activated slag-fly ash blends: Reaction kinetics, gel structure and carbon footprint
In this paper, a green olivine nano-silica is synthesized and applied as an alternative silicate source to prepare alkali activators, and a commercial waterglass based silica source is studied as a reference. The synthesis route and characterization of olivine nano-silica is presented. The effects of silicate origin and dosage on activator characteristics, reaction kinetics, gel structure and strength are investigated and the CO{sub 2} footprint is evaluated. The results show that increasing the activator modulus significantly increases the high crosslink Q contents in the alkali solution, nano-silica based ones exhibit slightly higher percentages of Q3 sites. Nano-silica based mixes exhibit comparable properties regarding the reaction intensity, chemically bound water content and strength. Gel compositions of both nano-silica and waterglass based samples are characterized in detail by using solid {sup 29}Si and {sup 27}Al MAS NMR. Moreover, replacing commercial waterglass by this alternative silicate source reduces the CO{sub 2} emission between 20.4% and 29.0%.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Active learning of constitutive relation from mesoscopic dynamics for macroscopic modeling of non-Newtonian flows
We simulate complex fluids by means of an on-the-fly coupling of the bulk rheology to the underlying microstructure dynamics. In particular, a continuum model of polymeric fluids is constructed without a pre-specified constitutive relation, but instead it is actively learned from mesoscopic simulations where the dynamics of polymer chains is explicitly computed. To couple the bulk rheology of polymeric fluids and the microscale dynamics of polymer chains, the continuum approach (based on the finite volume method) provides the transient flow field as inputs for the (mesoscopic) dissipative particle dynamics (DPD), and in turn DPD returns an effective constitutive relation to close the continuum equations. In this multiscale modeling procedure, we employ an active learning strategy based on Gaussian process regression (GPR) to minimize the number of expensive DPD simulations, where adaptively selected DPD simulations are performed only as necessary. Numerical experiments are carried out for flow past a circular cylinder of a non-Newtonian fluid, modeled at the mesoscopic level by bead-spring chains. The results show that only five DPD simulations are required to achieve an effective closure of the continuum equations at Reynolds number RE = 10. Furthermore, when Re is increased to 100, only one additional DPD simulation is required for constructing an extended GPR-informed model closure. Compared to traditional message-passing multiscale approaches, applying an active learning scheme to multiscale modeling of non-Newtonian fluids can significantly increase the computational efficiency. Although the method demonstrated here obtains only a local viscosity from the polymer dynamics, it can be extended to other multiscale models of complex fluids whose macro-rheology is unknown.
Computer Science↗
First-Principles Search for Efficient Activators for LaI3
First-principles calculations were performed using density functional theory with Hubbard corrections or hybrid exchange-correlation functionals, as well as the GW approximation, to identify activator dopants that could maximize the light yield of LaI3, a potentially very bright scintillator. The dopants considered in this work included a series of lanthanide ions (Ce, Pr, Nd, Eu, Gd, and Tb) and several ns2 ions (Tl, Pb, Sb, and Bi). Based on both ground-state calculations and constrained DFT calculations to simulate excited states, the trivalent lanthanide dopants were shown not to constitute an improvement over Ce3+, for which experimental data exist, as they showed occupied 4f states below the valence band maximum (VBM) and 5d states above the conduction band maximum (CBM). In contrast, the only divalent lanthanide considered, Eu2+, displayed occupied 4f states within the band gap of the host, but its 5d states were calculated to be above the CBM. Eu2+ could nonetheless be exploited as an activator by increasing the band gap energy slightly through substitution of iodide ions by bromide ions. Similar results were obtained for Tl+. Finally, Bi3+ and Sb3+ were predicted to be efficient activators in LaI3 by virtue of having unoccupied p states below the CBM, which can serve as electron traps and can combine with holes at the VBM to form localized emission centers. Comparison with empirical relationships of the relative positions of the energy levels of rare-earth dopants and implications for efficient doping schemes and scintillation mechanisms in LaI3 are also discussed.
Wu, Dangxin↗
Oxygen storage properties and catalytic activity of layer-ordered perovskites BaY1−Gd Mn2O5+
Not Available
Klimkowicz, A.↗
The proteasome inhibitor bortezomib induces testicular toxicity by upregulation of oxidative stress, AMP-activated protein kinase (AMPK) activation and deregulation of germ cell development in adult murine testis
Understanding how chemotherapeutic agents mediate testicular toxicity is crucial in light of compelling evidence that male infertility, one of the severe late side effects of intensive cancer treatment, occurs more often than they are expected to. Previous study demonstrated that bortezomib (BTZ), a 26S proteasome inhibitor used to treat refractory multiple myeloma (MM), exerts deleterious impacts on spermatogenesis in pubertal mice via unknown mechanisms. Here, we showed that intermittent treatment with BTZ resulted in fertility impairment in adult mice, evidenced by testicular atrophy, desquamation of immature germ cells and reduced caudal sperm storage. These deleterious effects may originate from the elevated apoptosis in distinct germ cells during the acute phase and the subsequent disruption of Sertoli–germ cell anchoring junctions (AJs) during the late recovery. Mechanistically, balance between AMP-activated protein kinase (AMPK) activation and Akt/ERK pathway appeared to be indispensable for AJ integrity during the late testicular recovery. Of particular interest, the upregulated testicular apoptosis and the following disturbance of Sertoli–germ cell interaction may both stem from the excessive oxidative stress elicited by BTZ exposure. We also provided the in vitro evidence that AMPK-dependent mechanisms counteract follicle-stimulating hormone (FSH) proliferative effects in BTZ-exposed Sertoli cells. Collectively, BTZ appeared to efficiently prevent germ cells from normal development via multiple mechanisms in adult mice. Employment of antioxidants and/or AMPK inhibitor may represent an attractive strategy of fertility preservation in male MM patients exposed to conventional BTZ therapy and warrants further investigation. - Highlights: • Intermittent treatment with BTZ caused fertility impairment in adult mice. • BTZ treatment elicited apoptosis during early phase of testicular recovery. • Up-regulation of oxidative stress by BTZ treatment disrupted AJs dynamics. • BTZ treatment stimulated AMPK activity during late phase of testicular recovery. • AMPK-dependent mechanisms counteract FSH proliferative effects in BTZ-exposed SCs.
60 APPLIED LIFE SCIENCES↗
6-Shogaol, an active compound of ginger, alleviates allergic dermatitis-like skin lesions via cytokine inhibition by activating the Nrf2 pathway
Allergic dermatitis (AD) clinically presents with skin erythematous plaques, eruption, and elevated serum IgE, and T helper cell type 2 and 1 (Th2 and Th1) cytokine levels. 6-Shogaol [1-(4-hydroxy-methoxyphenyl)-4-decen-one], a pungent compound isolated from ginger, has shown anti-inflammatory effects, but its inhibitory effects on AD are unknown. The aim of this study was to examine whether 6-shogaol inhibits AD-like skin lesions and their underlying mechanism in vivo and in vitro. An AD-like response was induced by tumor necrosis factor-α (TNF-α) + IFN-γ in human keratinocytes or by 2,4-dinitrochlorobenzene (DNCB) in mice. In vivo, 6-shogaol inhibited the development of DNCB-induced AD-like skin lesions and scratching behavior, and showed significant reduction in Th2/1-mediated inflammatory cytokines, IgE, TNF-α, IFN-γ, thymus and activation-regulated chemokine, IL-1, 4, 12, and 13, cyclooxygenase-2, and nitric oxide synthase levels. In vitro, 6-shogaol inhibited reactive oxygen species (ROS) and mitogen-activated protein kinases (MAPKs) signaling, and increased the levels of total glutathione, heme oxygenase-1, and quinone 1 via nuclear factor erythroid 2 related factor 2 (Nrf2) activation. 6-Shogaol can alleviate AD-like skin lesions by inhibiting immune mediators via regulating the ROS/MAPKs/Nrf2 signaling pathway, and may be an effective alternative therapy for AD. - Highlights: • 6-Shogaol inhibited Th2/1-mediated inflammatory mediators in vitro and in vivo. • 6-Shogaol regulated ROS/MAPKs/Nrf2 signaling pathway. • 6-Shogaol can protect against the development of AD-like skin lesions.
60 APPLIED LIFE SCIENCES↗
In-situ Characterization of Cu/CeO 2 Nanocatalysts during CO 2 Hydrogenation: Morphological Effects of Nanostructured Ceria on the Catalytic Activity
Here, a combination of time-resolved X-ray diffraction (TR-XRD), ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was used to carry out an in-situ characterization of Cu/CeO 2 nanocatalysts during the hydrogenation of CO 2 . Morphological effects of the ceria supports on the catalytic performances were investigated by examining the behavior of copper/ceria-nanorods (NR) and nanospheres (NS). At atmospheric pressures, the hydrogenation of CO 2 on the copper-ceria catalysts produced mainly CO through the reverse-water gas shift reaction (RWGS) and a negligible amount of methanol. The Cu/CeO 2 -NR catalyst displayed the higher activity, which demonstrates that the RWGS is a structure sensitive reaction. In-situ TR-XRD and AP-XPS characterization showed significant changes in the chemical state of the catalysts under reaction conditions with the copper being fully reduced and a partial Ce 4+ to Ce 3+ transformation occurring. A more effective CO 2 dissociative activation at high temperature and a preferential formation of active bidentate carbonate and formate intermediates over CeO 2 (110) terminations are probably the main reasons for the better performance of the Cu/CeO 2 -NR catalyst in the RWGS reaction.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Energy-Dispersive X-ray Diffraction: Operando Visualization of Electrochemical Activity of Thick Electrodes
Abstract not provided
Bruck, Andrea M.↗
Oxygen Evolution Reaction Activity in IrO x /SrIrO 3 Catalysts: Correlations between Structural Parameters and the Catalytic Activity
Understanding how structural properties affect the oxygen evolution reaction (OER) of a catalyst can reveal important information not only on the catalytic mechanism but also on the general design strategy of OER catalysts. We report a variation of ~0.15 V in the overpotential of the recently discovered IrO x /SrIrO 3 OER catalysts, which directly correlates with the structural parameters of the as-synthesized SrIrO 3 epitaxial films. This variation is caused by both extrinsic area enhancement and intrinsic electronic structure modification driven by defect formation. These correlations not only indicate that microscopic film defects play an important role in the activity of the IrO x /SrIrO 3 catalyst but also provide readily accessible parameters predictive of the activity post-transformation to IrO x /SrIrO 3 . Here, by establishing strong associations between the catalytic activity and key structural and electronic parameters, rather than synthetic variables, provides important guidance to control and study these complex catalysts independent of the synthetic technique.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗