Charge and discharge of methane on phenol-based carbon monolith

Methane adsorptions on various synthesized and commercial activated carbons were assessed in a volumetric apparatus for the design of an efficient adsorbed natural gas storage system. Based on the methane adsorption equilibrium results from different carbon based materials, a monolith was also produced from RP-20. Dynamic studies were also performed for the prepared monolith and the pelletized commercial Norit-B4 activated carbon. The temperature variation in RP-20 monolith was analyzed and compared with those of Norit-B4 and a blank test, which consisted of a run without a sample. The temperature variation in RP-20 monolith was quite high compared to that observed with Norit-B4 and the blank test because of a higher isosteric heat of adsorption and a high packing density.     

Networking of calixcrowns: from heteronuclear endo/exocyclic coordination polymers to a photoluminescence switch

Solvato-PL switching and shrinking-and-opening process: we present two CuI coordination polymers of calix[4]-bis-monothiacrown (L) obtained in the absence (1) and presence (2) of KI. The structures show not only very unusual CuI-based network arrangements but also unique reversible photolunimescence switching behavior induced by removal of coordinated solvent. Furthermore, upon inclusion of K+ ions the crown ring shrinks leading to "opening" of opposite aromatic rings in the host calixarene unit, rare behavior for this class of compound.     

Temperature-dependent 3-D CuI coordination polymers of calix[4]-bis-dithiacrown: crystal-to-crystal transformation and photoluminescence change on coordinated solvent removal

The temperature-dependent assembly of two 3-D CuI coordination polymers containing calix[4]-bis-thiacrown with different networking motifs are reported. Upon removal of the coordinated solvent molecules the initial solvent-coordinated polymer undergoes a unique single-crystal-to-single-crystal transformation to the desolvated polymer. Structural characteristics observed in the solvent-coordinated and the desolvated polymers also reveal related solvato-photolunimescence "off-on" behavior.     

Bi2Sn2O7 nanoparticles attached to SnO2 nanowires and used as catalysts

We introduce a simple method of synthesizing SnO₂ nanowire-Bi₂Sn₂O₇ nanoparticle composites based on the principle that SnO₂ nanowires can be grown by using Bi as catalysts. A mixture of Bi and Sn powders was thermally evaporated, and the effects of growth temperature on the morphology and structure of the products were investigated. We obtained Bi₂Sn₂O₇-tipped SnO₂ nanowires at 700 °C through a vapor–liquid–solid (VLS) process, whereas particle-free SnO₂ nanowires were produced at higher temperatures. We have investigated the oxygen sensing properties of the as-synthesized product.     

Origin of negative and dispersive features in anti-Stokes and resonance femtosecond stimulated Raman spectroscopy

Femtosecond stimulated Raman spectroscopy is extended to probe ground state anti-Stokes vibrational features. Off resonance, negative anti-Stokes features are seen that are the mirror image of the positive Stokes side spectra. On resonance, the observed dispersive lineshapes are dramatically dependent on the frequencies of the picosecond pump and femtosecond probe pulses used to generate the stimulated Raman spectra. These observations are explained by the contributions of the inverse Raman and hot luminescence four-wave mixing processes discussed by Sun et al. [J. Chem. Phys. 128, 144114 (2008)], which contribute to the overall femtosecond stimulated Raman signal.     

Valuation ideals and primary <Emphasis Type="Italic">w</Emphasis>-ideals

Let D be an integral domain, V (D) (resp., t-V (D)) be the set of all valuation (resp., t-valuation) ideals of D, and w-P(D) be the set of primary w-ideals of D. Let D[X] be the polynomial ring over D, c(f) be the ideal of D generated by the coefficients of f ∈ D[X], and N _v = {f ∈ D[X] | c(f) _v = D}. In this paper, we study integral domains D in which w-P(D) ? t-V (D), t-V (D) ? w-P(D), or t-V (D) = w-P(D). We also study the relationship between t-V (D) and \(V\left( {D{{\left[ X \right]}_{{N_v}}}} \right)\), and characterize when t-V (A + XB[X]) ? w-P(A + XB[X]) holds for a proper extension A ? B of integral domains.     

Glycerol steam reforming over Ni–Fe–Ce/Al2O3 catalyst for hydrogen production

Research on Chemical Intermediates - In this study, we focused on the catalytic activity, stability, and kinetics of glycerol steam reforming (GSR) for the hydrogen production over...     

Immobilization of the Gas Signaling Molecule H2S by Radioisotopes: Detection,Quantification, and In Vivo Imaging

Hydrogen sulfide (H₂S) has multifunctional roles as a gas signaling molecule in living systems. However, the efficient detection and imaging of H₂S in live animals is very challenging. Herein, we report the first radioisotope‐based immobilization technique for the detection, quantification, and in vivo imaging of endogenous H₂S. Macrocyclic ⁶⁴Cu complexes that instantly reacted with gaseous H₂S to form insoluble ⁶⁴CuS in a highly sensitive and selective manner were prepared. The H₂S concentration in biological samples was measured by a thin‐layer radiochromatography method. When ⁶⁴Cu–cyclen was injected into mice, an elevated H₂S concentration in the inflamed paw was clearly visualized and quantified by Cerenkov luminescence and positron emission tomography (PET) imaging. PET imaging was also able to pinpoint increased H₂S levels in a millimeter‐sized infarcted lesion of the rat heart.     

Non-linear dynamics of stable carbon and hydrogen isotope signatures based on a biological kinetic model of aerobic enzymatic methane oxidation

The non-linear dynamics of stable carbon and hydrogen isotope signatures during methane oxidation by the methanotrophic bacteria Methylosinus sporium strain 5 (NCIMB 11126) and Methylocaldum gracile strain 14 L (NCIMB 11912) under copper-rich (8.9 µM Cu²⁺), copper-limited (0.3 µM Cu²⁺) or copper-regular (1.1 µM Cu²⁺) conditions has been described mathematically. The model was calibrated by experimental data of methane quantities and carbon and hydrogen isotope signatures of methane measured previously in laboratory microcosms reported by Feisthauer et al. [1 Feisthauer S, Vogt C, Modrzynski J, Szlenkier M, Krüger M, Siegert M, Richnow HH. Different types of methane monooxygenases produce similar carbon and hydrogen isotope fractionation patterns during methane oxidation. Geochim Cosmochim Acta. 2011;75:1173–1184. doi: 10.1016/j.gca.2010.12.006[Crossref], [Web of Science ®] , [Google Scholar]] M. gracile initially oxidizes methane by a particulate methane monooxygenase and assimilates formaldehyde via the ribulose monophosphate pathway, whereas M. sporium expresses a soluble methane monooxygenase under copper-limited conditions and uses the serine pathway for carbon assimilation. The model shows that during methane solubilization dominant carbon and hydrogen isotope fractionation occurs. An increase of biomass due to growth of methanotrophs causes an increase of particulate or soluble monooxygenase that, in turn, decreases soluble methane concentration intensifying methane solubilization. The specific maximum rate of methane oxidation υ_m was proved to be equal to 4.0 and 1.3 mM mM^?1 h^?1 for M. sporium under copper-rich and copper-limited conditions, respectively, and 0.5 mM mM^?1 h^?1 for M. gracile. The model shows that methane oxidation cannot be described by traditional first-order kinetics. The kinetic isotope fractionation ceases when methane concentrations decrease close to the threshold value. Applicability of the non-linear model was confirmed by dynamics of carbon isotope signature for carbon dioxide that was depleted and later enriched in ¹³C. Contrasting to the common Rayleigh linear graph, the dynamic curves allow identifying inappropriate isotope data due to inaccurate substrate concentration analyses. The non-linear model pretty adequately described experimental data presented in the two-dimensional plot of hydrogen versus carbon stable isotope signatures.     

Soluble and easily crystallized anthracene derivatives: precursors of solution-processable semiconducting molecules

New soluble anthracene derivatives containing thiophene and phenylenevinylene derivatives were synthesized via well-known synthetic routes. TIPS derivatives were added at the 9,10-positions of anthracene for the solubility and crystallinity. Both of the molecules were found to be promising for high charge mobility and stable organic semiconductors. The soluble anthracene core (TIPSAnt) is a potential precursor for the synthesis of novel semiconducting materials.