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•Catalytic steam reforming of methane in an electric field was investigated over Pd/CeO2.•Operando–DRIFTS using isotope has been used to investigate the reaction mechanism.•Inverse ...kinetic isotope effect based on CHH vibration was observed.•Proton collision promoted methane activation irreversibly at low temperatures in an electric field.
To elucidate the reaction mechanism of catalytic steam reforming of methane in an electric field, operando–diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) has been used to investigate methane dissociative adsorption at low temperatures using CH4, H2O, and their isotopes. Operando-analyses demonstrated that methane was adsorbed and converted into CO and CO2 more when CD4 and/or D2O was used instead of CH4 and/or H2O. This observed “inverse” kinetic isotope effect is based on the difference of CHH vibrational energy level at the transition state. Furthermore, CO2-methanation, which is the reverse reaction of steam reforming of methane, was irreversible with H2O in an electric field. These results demonstrate that the proton collision promoted methane activation irreversibly, even at low temperatures in an electric field.
Catalytic steam reforming of methane for hydrogen production proceeds even at 473 K over 1 wt% Pd/CeO
catalyst in an electric field, thanks to the surface protonics. Kinetic analyses demonstrated the ...synergetic effect between catalytic reaction and electric field, revealing strengthened water pressure dependence of the reaction rate when applying an electric field, with one-third the apparent activation energy at the lower reaction temperature range. Operando-IR measurements revealed that proton conduction via adsorbed water on the catalyst surface occurred during electric field application. Methane was activated by proton collision at the Pd-CeO
interface, based on the inverse kinetic isotope effect. Proton conduction on the catalyst surface plays an important role in methane activation at low temperature. This report is the first describing promotion of the catalytic reaction by surface protonics.
Highlights • A review of the current status of Geant4-DNA is presented. • New physical models describing the interactions of electrons in water are described. • Physicochemical and chemical stages of ...water radiolysis can be simulated. • Several approaches are available for modeling geometries of biological targets. • Dedicated examples are proposed to demonstrate such capabilities.
Summary
The activation of nuclear factor‐kappa B (NF‐κB) in vascular endothelial cells may be involved in vascular pathogeneses such as vasculitis or atherosclerosis. Recently, it has been reported ...that some amino acids exhibit anti‐inflammatory effects. We investigated the inhibitory effects of a panel of amino acids on cytokine production or expression of adhesion molecules that are involved in inflammatory diseases in various cell types. The activation of NF‐κB was determined in human coronary arterial endothelial cells (HCAECs) because NF‐κB modulates the production of many cytokines and the expression of adhesion molecules. We examined the inhibitory effects of the amino acids cysteine, histidine and glycine on the induction of NF‐κB activation, expression of CD62E (E‐selectin) and the production of interleukin (IL)‐6 in HCAECs stimulated with tumour necrosis factor (TNF)‐α. Cysteine, histidine and glycine significantly reduced NF‐κB activation and inhibitor κBα (IκBα) degradation in HCAECs stimulated with TNF‐α. Additionally, all the amino acids inhibited the expression of E‐selectin and the production of IL‐6 in HCAECs, and the effects of cysteine were the most significant. Our results show that glycine, histidine and cysteine can inhibit NF‐κB activation, IκBα degradation, CD62E expression and IL‐6 production in HCAECs, suggesting that these amino acids may exhibit anti‐inflammatory effects during endothelial inflammation.
Nesfatin-1 is a novel satiety molecule in the hypothalamus and is also present in peripheral tissues. Here we sought to identify the active segment of nesfatin-1 and to determine the mechanisms of ...its action after peripheral administration in mice. Intraperitoneal injection of nesfatin-1 suppressed food intake in a dose-dependent manner. Nesfatin-1 has three distinct segments; we tested the effect of each segment on food intake. Injection of the midsegment decreased food intake under leptin-resistant conditions such as db/db mice and mice fed a high-fat diet. After injection of the midsegment, expression of c-Fos was significantly activated in the brainstem nucleus tractus solitarius (NTS) but not in the hypothalamic arcuate nucleus; the nicotinic cholinergic pathway to the NTS contributed to midsegment-induced anorexia. Midsegment injection significantly increased expression of proopiomelanocortin and cocaine- and amphetamine-regulated transcript genes in the NTS but not in the arcuate nucleus. Investigation of mutant midsegments demonstrated that a region with amino acid sequence similarity to the active site of agouti-related peptide was indispensable for anorexigenic induction. Our findings indicate that the midsegment of nesfatin-1 causes anorexia, possibly by activating POMC and CART neurons in the NTS via a leptin-independent mechanism after peripheral stimulation.
Peripherally administered nesfatin-1 and its mid-segment suppress food intake in mice. The nicotinic cholinergic pathway to the nucleus tractus solitarius contributes to the anorexigenic action of the mid-segment.
The development of van der Waals heterostructures has introduced unconventional phenomena that emerge at atomically precise interfaces. For example, interlayer excitons in two-dimensional transition ...metal dichalcogenides show intriguing optical properties at low temperatures. Here we report on room-temperature observation of interface excitons in mixed-dimensional heterostructures consisting of two-dimensional tungsten diselenide and one-dimensional carbon nanotubes. Bright emission peaks originating from the interface are identified, spanning a broad energy range within the telecommunication wavelengths. The effect of band alignment is investigated by systematically varying the nanotube bandgap, and we assign the new peaks to interface excitons as they only appear in type-II heterostructures. Room-temperature localization of low-energy interface excitons is indicated by extended lifetimes as well as small excitation saturation powers, and photon correlation measurements confirm antibunching. With mixed-dimensional van der Waals heterostructures where band alignment can be engineered, new opportunities for quantum photonics are envisioned.
Nanomaterials exhibit unique optical phenomena, in particular excitonic quantum processes occurring at room temperature. The low dimensionality, however, imposes strict requirements for conventional ...optical excitation, and an approach for bypassing such restrictions is desirable. Here we report on exciton transfer in carbon-nanotube/tungsten-diselenide heterostructures, where band alignment can be systematically varied. The mixed-dimensional heterostructures display a pronounced exciton reservoir effect where the longer-lifetime excitons within the two-dimensional semiconductor are funneled into carbon nanotubes through diffusion. This new excitation pathway presents several advantages, including larger absorption areas, broadband spectral response, and polarization-independent efficiency. When band alignment is resonant, we observe substantially more efficient excitation via tungsten diselenide compared to direct excitation of the nanotube. We further demonstrate simultaneous bright emission from an array of carbon nanotubes with varied chiralities and orientations. Our findings show the potential of mixed-dimensional heterostructures and band alignment engineering for energy harvesting and quantum applications through exciton manipulation.
A taxonomic study was made of the genus Leuconostoc. The species in the genus were divided into three subclusters by phylogenetic analysis based on the 16S rRNA gene sequences. The three subclusters ...were the Leuconostoc mesenteroides subcluster (comprising L. carnosum, L. citreum, L. gasicomitatum, L. gelidum, L. inhae, L. kimchii, L. lactis, L. mesenteroides and L. pseudomesenteroides), the L. fructosum subcluster (L. durionis, L. ficulneum, L. fructosum and L. pseudoficulneum) and the L. fallax subcluster (L. fallax). Phylogenetic trees based on the sequences of the 16S-23S rRNA gene intergenic spacer region, the rpoC gene or the recA gene indicated a good correlation with the phylogenetic tree based on 16S rRNA gene sequences. The species in the L. fructosum subcluster were morphologically distinguishable from the species in the L. mesenteroides subcluster and L. fallax as species in the L. fructosum subcluster had rod-shaped cells. In addition, the four species in the L. fructosum subcluster needed an electron acceptor for the dissimilation of d-glucose and produced acetic acid from d-glucose rather than ethanol. On the basis of evidence presented in this study, it is proposed that the four species in the L. fructosum subcluster, Leuconostoc durionis, Leuconostoc ficulneum, Leuconostoc fructosum and Leuconostoc pseudoficulneum, should be transferred to a novel genus, Fructobacillus gen. nov., as Fructobacillus durionis comb. nov. (type strain D-24(T)=LMG 22556(T)=CCUG 49949(T)), Fructobacillus ficulneus comb. nov. (type strain FS-1(T)=DSM 13613(T)=JCM 12225(T)), Fructobacillus fructosus comb. nov. (type strain IFO 3516(T)=DSM 20349(T)=JCM 1119(T)=NRIC 1058(T)) and Fructobacillus pseudoficulneus comb. nov. (type strain LC-51(T)=DSM 15468(T)=CECT 5759(T)). The type species of the genus Fructobacillus is Fructobacillus fructosus gen. nov., comb. nov.. No significant physiological and biochemical differences were found between the species in the L. mesenteroides subcluster and L. fallax in the present study and thus L. fallax remains as a member of the genus Leuconostoc.
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