1,420 research outputs found

    Design, Synthesis and 5-HT1A Binding Affinity of N-(3-(4-(2-Methoxyphenyl)piperazin-1-yl)propyl)tricyclo[3.3.1.13,7 ]decan-1-amine and N-(3-(4-(2-Methoxyphenyl) piperazin-1-yl)propyl)-3,5-dimethyl-tricylo[3.3.1.13,7 ]decan-1-amine

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    Based on previously highlighted structural features, the development of highly selective 5-HT1A receptor inhibitors is closely linked to the incorporation of a 4-alkyl-1-arylpiperazine scaffold on them. In this paper, we present the synthesis of two new compounds bearing the 2-MeO-Ph-piperazine moiety linked via a three carbon atom linker to the amine group of 1-adamantanamine and memantine, respectively. Both were tested for their binding affinity against 5-HT1A receptor. N-(3-(4-(2-methoxyphenyl)piperazin-1-yl)propyl)tricyclo[3.3.1.13,7 ]decan-1-amine fumarate (8) and N-(3-(4-(2-methoxyphenyl)piperazin-1-yl)propyl)-3,5-dimethyl-tricylo[3.3.1.13,7 ]decan-1-amine fumarate (10) proved to be highly selective ligands towards 5-HT1A receptor with a binding constant of 1.2 nM and 21.3 nM, respectively, while 5-carboxamidotriptamine (5-CT) (2) was used as an internal standard for this assay with a measured Ki = 0.5 nM

    Yields of oxidized volatile organic compounds during the OH radical initiated oxidation of isoprene, methyl vinyl ketone, and methacrolein under high-NO_x conditions

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    We present first-generation and total production yields of glyoxal, methylglyoxal, glycolaldehyde, and hydroxyacetone from the oxidation of isoprene, methyl vinyl ketone (MVK), and methacrolein (MACR) with OH under high NO_x conditions. Several of these first-generation yields are not included in commonly used chemical mechanisms, such as the Leeds Master Chemical Mechanism (MCM) v. 3.2. The first-generation yield of glyoxal from isoprene was determined to be 2.1 (±0.6)%. Inclusion of first-generation production of glyoxal, glycolaldehyde and hydroxyacetone from isoprene greatly improves performance of an MCM based model during the initial part of the experiments. In order to further improve performance of the MCM based model, higher generation glyoxal production was reduced by lowering the first-generation yield of glyoxal from C5 hydroxycarbonyls. The results suggest that glyoxal production from reaction of OH with isoprene under high NO_x conditions can be approximated by inclusion of a first-generation production term together with secondary production only via glycolaldehyde. Analogously, methylglyoxal production can be approximated by a first-generation production term from isoprene, and secondary production via MVK, MACR and hydroxyacetone. The first-generation yields reported here correspond to less than 5% of the total oxidized yield from isoprene and thus only have a small effect on the fate of isoprene. However, due to the abundance of isoprene, the combination of first-generation yields and reduced higher generation production of glyoxal from C5 hydroxycarbonyls is important for models that include the production of the small organic molecules from isoprene

    Analysis of photochemical and dark glyoxal uptake: Implications for SOA formation

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    The dependence of glyoxal uptake onto deliquesced ammonium sulfate seed aerosol was studied under photochemical (light + hydroxyl radical (OH)) and dark conditions. In this study, the chemical composition of aerosol formed from glyoxal is identical in the presence or absence of OH. In addition, there was no observed OH dependence on either glyoxal uptake or glyoxal-driven aerosol growth for this study. These findings demonstrate that, for the system used here, glyoxal uptake is not affected by the presence of OH. In combination with previous studies, this shows that the exact nature of the type of seed aerosol, in particular the presence of a coating, has a large influence on fast photochemical uptake of glyoxal. Due to the challenge of relating this seed aerosol dependence to ambient conditions, this work highlights the resulting difficulty in quantitatively including SOA formation from glyoxal in models

    Distribution and growth styles of isolated carbonate platforms as a function of fault propagation

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    Fault control on the position and distribution of isolated carbonate platforms is investigated in Northwest Australia using high-quality 3D seismic and borehole data from the Bonaparte Basin. Specifically, we address the relationship between carbonate productivity and fault growth so as to understand what are the primary controls on the growth of isolated carbonate platforms. Throw-depth (T-Z) and throw-distance (T-D) profiles for normal faults suggest they formed fault segments that were linked at different times in the study area. This caused differential vertical movements; some of the normal faults propagated to the surface, while others have upper tips that are 19–530 ms two-way-time below the sea floor, with the largest throw values comprising faults underneath isolated carbonate platforms. As a result, four distinct zones correlate with variable geometries and sizes of carbonate platforms, which are a function of the topographic relief generated by underlying propagating faults. Some relay ramps form the preferred location for the initiation and development of carbonate platforms, together with adjacent structural highs. Due to the complex effect of fault propagation to the palaeo-seafloor, and soft-linkage through relay ramps, three distinct ICP types are proposed: (1) in the first type, fault throw is larger than carbonate productivity; (2) the second type considers fault throw to be equal or less than carbonate productivity; and (3) in the third type, fault throw post-dates the growth of the carbonate platform(s). The analysis of fault propagation vs. carbonate platform growth shown here is important, as the three ICP types proposed, potentially correlate with variable fracture densities and distributions within the carbonate platforms. Based on our results, types 2 and 3 above enhance fracture- and fault-dominated porosity and permeability to a greater degree, making them favourable targets for hydrocarbon exploration

    α-pinene photooxidation under controlled chemical conditions – Part 2: SOA yield and composition in low- and high-NO_x environments

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    The gas-phase oxidation of α-pinene produces a large amount of secondary organic aerosol (SOA) in the atmosphere. A number of carboxylic acids, organosulfates and nitrooxy organosulfates associated with α-pinene have been found in field samples and some are used as tracers of α-pinene oxidation. α-pinene reacts readily with OH and O_3 in the atmosphere followed by reactions with both HO_2 and NO. Due to the large number of potential reaction pathways, it can be difficult to determine what conditions lead to SOA. To better understand the SOA yield and chemical composition from low- and high-NO_x OH oxidation of α-pinene, studies were conducted in the Caltech atmospheric chamber under controlled chemical conditions. Experiments used low O_3 concentrations to ensure that OH was the main oxidant and low α-pinene concentrations such that the peroxy radical (RO_2) reacted primarily with either HO_2 under low-NO_x conditions or NO under high-NO_x conditions. SOA yield was suppressed under conditions of high-NO_x. SOA yield under high-NO_x conditions was greater when ammonium sulfate/sulfuric acid seed particles (highly acidic) were present prior to the onset of growth than when ammonium sulfate seed particles (mildly acidic) were present; this dependence was not observed under low-NO_x conditions. When aerosol seed particles were introduced after OH oxidation, allowing for later generation species to be exposed to fresh inorganic seed particles, a number of low-NO_x products partitioned to the highly acidic aerosol. This indicates that the effect of seed acidity and SOA yield might be under-estimated in traditional experiments where aerosol seed particles are introduced prior to oxidation. We also identify the presence of a number of carboxylic acids that are used as tracer compounds of α-pinene oxidation in the field as well as the formation of organosulfates and nitrooxy organosulfates. A number of the carboxylic acids were observed under all conditions, however, pinic and pinonic acid were only observed under low-NO_x conditions. Evidence is provided for particle-phase sulfate esterification of multi-functional alcohols

    Fingerprinting Chamaesiphon populations as an approach toassess the quality of running waters

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    "This is the peer reviewed version of the following article: Loza, V.; Morales, A.; Perona, E. and Muñoz-Martín, M. A."Fingerprinting Chamaesiphon populations as an approach toassess the quality of running waters" River Research and Applications 34 (2018): 595-605 which has been published in final form at https://doi.org/10.1002/rra.3277. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions."Cyanobacterial communities are highly diverse in freshwaters and respond rapidly tochanging environments. Previous studies have highlighted variations in the structureand composition of epilithic cyanobacterial communities in response to eutrophica-tion in watercourses. In the present study, changes in benthic cyanobacterial commu-nities from Guadalix River (Spain) biofilms were examined using temperature‐gradientgel electrophoresis (TGGE) in conjunction with microscopic examination of field‐fixedsamples, focusing on populations of one of the dominant cyanobacteria:Chamaesiphon. Environmental characteristics were determined in order to character-ize the trophic status of the sampling sites. The presence of cyanobacteria in the riverwas determined from complex TGGE patterns, band extraction, and subsequentsequencing of 16S rDNA gene fragments. The microscopic observations revealed thatthe unicellular genus Chamaesiphon and the filamentous genus Phormidium were dom-inant in the studied locations. Within the 2 genera, 4 Chamaesiphon populations wereidentified (Chamaesiphon fuscus, Chamaesiphon starmachii, Chamaesiphon subglobosus ,and Chamaesiphon polymorphus) and Phormidium was represented at the samplingsites by the Phormidium autumnale morphotype. TGGE banding patterns differedamong samplings sites as a function of water quality. The genetic analysis revealed4 phylotypes within the genus Chamaesiphon and 1 phylotype within the classicP. autumnale clade. Chamaesiphon phylotypes were not equally distributed in all thesampling locations. Some phylotypes were related to low nutrient concentrations,while others were associated with eutrophic conditions. Our results support the useof fingerprints of Chamaesiphon populations obtained by TGGE to examine changesin water quality.This work was supported by Grant CGL2013‐44870‐R from the Ministerio de Economía y Competitividad, Spai
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