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Naoko Inoue, Toshiya Tada, Katsuya Kawamoto
In the gasification of biomass, it is necessary to limit the amount of by-product tar and increase the yields of hydrogen and carbon monoxide (syngas). Therefore, we conducted gasification and reforming experiments on woody biomass using an electric tubular furnace, to evaluate the gas reforming and tar decomposition performance of a NiO/SBA-15 catalyst. As a result, we found that this catalyst is effective for H2 production. It is believed that the increase in H2 volume due to the catalyst occurs through a steam reforming reaction involving hydrocarbons including CH4 , and the water-gas shift reaction...
December 12, 2018: Journal of the Air & Waste Management Association
Zdenek Futera, Jochen Blumberger
The interaction of amino acids with metal electrodes plays a crucial role in bioelectrochemistry and the emerging field of bionanoelectronics. Here we present benchmark calculations of the adsorption structure and energy of all natural amino acids on Au(111) in vacuum using a van-der-Waals density functional (revPBE-vdW) that showed good performance on the S22 set of weakly bound dimers (mean relative unsigned error (MRUE) wrt CCSD(T)/CBS = 13.3%) and adsorption energies of small organic molecules on Au(111) (MRUE wrt experiment = 11...
December 12, 2018: Journal of Chemical Theory and Computation
A-Reza Nekoei, Morteza Vatanparast
Quantum DFT calculations, corrected for long-range interactions, have been carried out on complex models formed between HF as a proton donor and 2-methylene-2H-indene derivatives as proton acceptors. Using various exocyclic X substitutions, mutual effects of the aromaticity and the strength of the resulting π-hydrogen bond (after its evaluation by AIM methodology) have been investigated. The results show that the aromaticity of 6-membered rings and the hydrogen bond strength increase upon increasing the electron-donating character of the X-substituents...
December 12, 2018: Physical Chemistry Chemical Physics: PCCP
Mathias Steglich, Gregor Knopp, Patrick Hemberger
Excited xylyl (methyl-benzyl) radical isomers have been studied by femtosecond time-resolved photoelectron spectroscopy and mass spectrometry. Depending on the substitution we find different deactivation channels after excitation into the D3(2A'') state (310 nm, 4 eV). While the ortho and para isomer exhibit deactivation rates similar to the benzyl radical, meta-xylyl sticks out and depletes twice as fast into the vibrationally hot ground state. We found that a ring deformation mode rather than the methyl pseudorotation enables access to a conical intersection, which is responsible for the faster deactivation...
December 12, 2018: Physical Chemistry Chemical Physics: PCCP
Eun-Sun Kim, Hongjun Jang, Sun-Young Chang, Seung-Hoon Baek, Ok-Nam Bae, Hyoungsu Kim
A concise synthesis of sericetin (1) was performed in four steps from readily available 3- O-benzylgalangin (4), featuring electrocyclization to produce the tricyclic core and a sequential aromatic Claisen/Cope rearrangement to incorporate the 8-prenyl group of 1. In addition, the therapeutic potential of sericetin (1), isosericetin (2), and three prenylated tetracyclic synthetic intermediates (11, 12, and 14) against cisplatin-induced nephrotoxicity using renal tubular cells were evaluated. Compound 14 showed therapeutic potential against cisplatin-induced kidney damage...
December 12, 2018: Journal of Natural Products
Kuei-Yen Huang, Jia-Cherng Horng
Cis-trans isomerization of proline is involved in various biological processes, such as protein folding, cell signaling, and ion-channel gating. Polyproline is a useful system for better understanding proline isomerization because it exists predominantly as two forms, all-cis polyproline I (PPI) and all-trans polyproline II (PPII) helices. The stability of PPI and PPII can be modulated by various effects, including aromatic-proline interactions, terminal charges, and stereoelectronic effects. Here we used a series of oligoproline peptides in which positively charged or negatively charged amino acids were incorporated into the termini to investigate their effects on polyproline conformation...
December 12, 2018: Journal of Physical Chemistry. B
María Elisa Pavan, Esmeralda Solar Venero, Diego E Egoburo, Esteban E Pavan, Nancy I López, M Julia Pettinari
The environmental strain Aeromonas salmonicida subsp. pectinolytica 34melT produces abundant melanin through the homogentisate pathway in several culture media, but unexpectedly not when grown in a medium containing glycerol. Using this observation as a starting point, this study investigated the underlying causes of the inhibition of melanin synthesis by glycerol, to shed light on factors that affect melanin production in this microorganism. The effect of different carbon sources on melanin formation was related to the degree of oxidation of their C atoms, as the more reduced substrates delayed melanization more than the more oxidized ones, although only glycerol completely abolished melanin production...
December 11, 2018: Applied Microbiology and Biotechnology
Leonid B Krivdin
Structural applications of theoretical calculations of carbon-hydrogen spin-spin coupling constants are reviewed covering papers published mainly during the last 10-15 years with a special emphasis on the most notable studies of hybridization, substitution and stereoelectronic effects together with the investigation of hydrogen bonding and intermolecular interactions. The wide scope of different applications of calculated carbon-hydrogen couplings in the structural elucidation of particular classes of organic and bioorganic molecules is reviewed, concentrating mainly on saturated, unsaturated, aromatic and heteroaromatic compounds and their functional derivatives, as well as on natural compounds and carbohydrates...
October 2018: Progress in Nuclear Magnetic Resonance Spectroscopy
Ruifei Wang, Xuanyu Chen, Qingxiang Yang
  In this study a laboratory-scale sequencing batch bioreactor was constructed, using phenanthrene/pyrene as the sole carbon-source, to demonstrate the removal efficiencies of polycyclic aromatic hydrocarbons (PAHs) and the evolution process of a functional bacterial community. The removal rates were: COD, 51.4 to 76.3%; phenanthrene, 63.5 to 92.4%; and pyrene, 65.9 to 90.1%. Quantification analysis indicated that in sludge samples from the phenanthrene/pyrene degradation stage, the contents of 16S rRNA and ring-hydroxylating dioxygenase genes of Gram-positive and Gram-negative bacteria were 10-and 72-, 102- and 1152-, 31- and 905-fold higher, respectively, than those in seed sludge samples...
December 1, 2018: Water Environment Research: a Research Publication of the Water Environment Federation
Xiang Wu, Lizhong Zhu
Predicting the translocation of organic contaminants to plants is crucial to ensure the quality of agricultural goods and assess the risk of human exposure through the food web. In this study, the performance of a modified plant uptake model was evaluated considering a number of chemicals, such as polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs), with a range of physicochemical properties; different plant species (Ipomoea aquatica Forsk (swamp morning glory), Chrysanthemum coronarium L...
November 30, 2018: Environmental Pollution
Simon Aldridge, Lilja Kristinsdottir, Petra Vasko, Haoyu Niu, Eugene Kolychev, Jesus Campos, Maria Angeles Fuentes, Jamie Hicks, Amber L Thompson
This study details attempts to access N-heterocyclic carbenes (NHCs) featuring the diazaborolyl group, {(HCNDipp)2B}, as one or both of the N-bound substituents. Attempts to isolate N-heterocyclic carbenes based around imidazolylidene or related heterocycles, are characterized by facile N-to-C migration of the boryl substituent. In the cases of imidazolium precursors bearing one N-bound diazaboryl group and one methyl substituent, deprotonation leads to the generation of the target carbenes, which can be characterized in situ by NMR measurements, and trapped by reactions with metal fragments and elemental selenium...
December 11, 2018: Chemistry: a European Journal
Isabella Panovic, Christopher S Lancefield, Darren Phillips, Mark Gronnow, Nicholas James Westwood
Chemically modified lignins are important for the generation of biomass-derived materials and as precursors to renewable aromatic monomers. A butanol-based organosolv pretreatment has been used to convert an abundant agricultural waste product, rice husks, into a cellulose pulp and three additional product streams. One of these streams, a butanol-modified lignin, was oxidised at the γ-position to give a carboxylic acid functionalized material. Subsequent coupling of the acid with aniline aided lignin characterization and served as an example of the flexibility of this approach for grafting side chains onto a lignin core structure...
December 10, 2018: ChemSusChem
Kui Wu, Lushun Wang, Sonivette Colon-Rodriguez, Gerd-Uwe Flechsig, Ting Wang
The development of visible-light-mediated allylation of unactivated sp3 C-H bonds is reported. The remote allylation was directed by the amidyl radical, which was generated by photocatalytic fragmentation of a pre-functionalized amide precursor. Both aromatic and aliphatic amide derivatives could successfully deliver the remote C-H allylation products in good yields. A variety of electron deficient allyl sulfone systems could be used as δ-carbon radical acceptor.
December 10, 2018: Angewandte Chemie
Anupam Giri, Marion Coutriade, Amandine Racaud, Pierre-Hugues Stefanuto, Koji Okuda, John Dane, Robert B Cody, Jean-François Focant
Comprehensive two-dimensional gas chromatography (GC×GC) coupled to time-of-flight mass spectrometry is a powerful separation tool for complex petroleum product analysis. However, the most commonly used electron ionization (EI) technique often makes the identification of the majority of hydrocarbons impossible due to the exhaustive fragmentation and lack of molecular ion preservation, prompting the need of soft-ionization energies. In this study, three different soft-ionization techniques including photo ionization (PI), chemical ionization (CI), and field ionization (FI) were compared against EI to elucidate their relative capabilities to reveal different base oil hydrocarbon classes...
December 7, 2018: Journal of Mass Spectrometry: JMS
B E Finch, W A Stubblefield
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the environment as components in complex mixtures derived from petroleum based products. PAHs are unique in their ability to absorb UV light, resulting in significant increases in acute toxicity. The objective of this study was to determine if mixtures of the phototoxic PAHs fluoranthene, pyrene, and anthracene conform to the additive model of toxicity. Median lethal concentrations (LC50) were calculated for mysid shrimp (Americamysis bahia) and inland silverside (Menidia beryllina) exposed to individual, binary, and ternary mixtures of the selected PAHs...
December 10, 2018: Bulletin of Environmental Contamination and Toxicology
Lenny Kamelia, Sylvia Brugman, Laura de Haan, Hans B Ketelslegers, Ivonne M C M Rietjens, Peter J Boogaard
The present study evaluates the applicability of the zebrafish embryotoxicity test (ZET) to assess prenatal developmental toxicity (PDT) potency of the DMSO-extracts of 9 petroleum substances (PS), with variable polycyclic aromatic hydrocarbon (PAH) content, and 2 gas-to-liquid (GTL) products, without any PAHs but otherwise similar properties to PS. The results showed that all PS extracts induced concentration-dependent in vitro PDT, as quantified in the ZET and that this potency is associated with their 3-5 ring PAH content...
December 7, 2018: ALTEX
Junais Habeeb Mokkath
Polycyclic aromatic hydrocarbons (PAHs), the molecular version of graphene, having edges saturated with hydrogen atoms, have recently emerged as a novel nanoplasmonic material. In this work, we investigate the optical properties of pristine and pyridine adsorbed circular and triangular PAHs. We base our calculations on computationally efficient first-principles time-dependent density-functional theory (TD-DFT) calculations. We find substantial changes in the optical absorption spectra induced by the presence of the pyridine molecule...
December 10, 2018: Physical Chemistry Chemical Physics: PCCP
Fang Wang, Xinying Zhang, Yan He, Xuesen Fan
In this paper, a selective synthesis of pyrrolidin-2-ones and 3-iodopyrroles via the cascade reactions of N-substituted piperidines is presented. Mechanistically, the formation of pyrrolidin-2-ones involves a domino process including the in situ formation of pyrrolidine-2-carbaldehyde followed by carboxylic acid formation, decarboxylation and ipso-oxidation. On the other hand, 3-iodopyrroles are believed to be formed via the initial generation of pyrrolidine-2-carbaldehyde followed by carboxylic acid formation, decarboxylation, dehydrogenation, iodination and aromatization...
December 10, 2018: Organic & Biomolecular Chemistry
Daniel R Blechschmidt, Matthew D Woodhouse, Sebastien Inagaki, Melita Whitfield, Ayokunnumi Ogunsanya, Aaron Yoder, Daniel Lilly, Eric W Heim, Luke N Soucie, Jian Liang, Yu Liu
Three generations of Co(iii)-salen complexes containing electron-deficient aromatic moieties (acceptors) have been synthesized. When electron-rich aromatic compounds (donors) were introduced, these complexes were designed to form catalyst assemblies through aromatic donor-acceptor interaction. For all three generations of complexes, the addition of a proper donor led to higher catalytic efficiency in the hydrolytic kinetic resolution (HKR) of epichlorohydrin. The reaction rates are in the following order: Generation 3 > Generation 2 > Generation 1...
December 10, 2018: Organic & Biomolecular Chemistry
Shigeki Watanabe, Mohammad Anwar-Ul Azim, Ichiro Nishinaka, Ichiro Sasaki, Yasuhiro Ohshima, Keiichi Yamada, Noriko S Ishioka
The 211At-labeled compound, 4-[211At]astato-l-phenylalanine, is one of the most promising amino acid derivatives for use in targeted alpha therapy (TAT) for various cancers. Electrophilic demetallation of a stannyl precursor is the most widely used approach for labeling biomolecules with 211At. However, the low acid-resistance of the stannyl precursor necessitates the use of an N- and C-terminus-protected precursor, which results in a low overall radiochemical yield (RCY) due to the multiple synthetic steps involved...
December 10, 2018: Organic & Biomolecular Chemistry
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