345 research outputs found
Quinolines from oxime o-acetates
The photochemistry of a number of arylidenecyclopentanone oxime 0 - acetates has been investigated Irradiation in methanol leads to initial E-Z geometrical isomérisation and ultimately to the formation of nitrogen containing heterocycles, via a 6îr-electron photocyclisation process, followed by an elimination.
The scope of the reactions has been extended by investigation of substrates incorporating a range of electron-donating aryl substituents The photocyclisations of 2-(4-dimethylaminobenzyhdene)-, 2-(4-hydroxybenzylidene)-, 2-(4-acetoxybenzylidene) and 2-(2,5-dimethoxybenzylidene) cyclopentanone oxime O-acetates and 2-(4-aminobenzylidene) cyclopentanone oxime were investigated.
Substitutents in the 3-position of the aryl system may potentially result in cyclisation at either the 2- or 6-positions of the aryl group. In practice cyclisation has been found to be highly regioselective The range of regioselective reactions has been extended by substitution in the aryl 3- position with t-butyl, hydroxy, acetoxy, dimethylamino and ammo groups. The regioselectivity of the cyclisation reaction has also been investigated with a number of disubstituted aryl groups.
An oxime O-acetate denvative of phenothiazine, underwent cyclisation as did 2-(3-phenyl-allylidene)cyclopentanone oxime O-acetate. The leaving group in these cyclisation reactions is oxygen-based. A preliminary investigation into a small number of nitrogen-based leaving groups was carried out.
Semi-empirical calculations were earned out on a number of 3- substituted oxime O-acetates to investigate the reasons for the observed regioselectivities during photocyclisation
Quinoline synthesis: scope and regiochemistry of photocyclisation of substituted benzylidenecyclopentanone O-alkyl and O-acetyloximes
Irradiation of substituted 2-benzylidenecyclopentanone O-alkyl and O-acetyloximes in methanol provides a convenient synthesis of alkyl, alkoxy, hydroxy, acetoxy, amino, dimethylamino and benzo substituted annulated quinolines. para-Substituents yield 6-substituted-2,3-dihydro-1H-cyclopenta[b]quinolines with 8-substituted products being obtained from ortho-substituted starting materials. Reactions of meta-substituted precursors are highly regioselective, with alkyl substituents leading to 5-substituted 2,3-dihydro-1H-cyclopenta[b]quinolines and more strongly electron-donating substituents generally resulting in 7-substituted products. 2-Furylmethylene and 2-thienylmethylene analogues yield annulated furo- and thieno-[2,3e]pyridines respectively. Sequential E- to Z-benzylidene group isomerisation and six [pi]-electron cyclisation steps result in formation of a short-lived dihydroquinoline intermediate which spontaneously aromatises by elimination of an alcohol or acetic acid. For 2-benzylidenecyclopentanone O-allyloxime, singlet excited states are involved in both steps
Oxygenase Domain of Drosophila melanogaster Nitric Oxide Synthase: Unique Kinetic Parameters Enable a More Efficient NO Release
Although nitric oxide (NO) is important for cell signaling and nonspecific immunity in the fruit fly Drosophila melanogaster, little is known about its single NO synthase (dNOS). We expressed the oxygenase domain of dNOS (dNOSoxy), characterized its spectroscopic, kinetic, and catalytic properties, and interpreted them in light of a global kinetic model for NO synthesis. Single turnover reactions with ferrous dNOSoxy showed it could convert Arg to N'omega-hydroxy-l-arginine (NOHA), or NOHA to citrulline and NO, when it was given 6R-tetrahydrobiopterin and O2. The dNOSoxy catalyzed Arg hydroxylation and NOHA oxidation at rates that matched or exceeded the rates catalyzed by the three mammalian NOSoxy enzymes. Consecutive heme-dioxy, ferric heme-NO, and ferric heme species were observed in the NOHA reaction of dNOSoxy, indicating that its catalytic mechanism is the same as in the mammalian NOS. However, NO dissociation from dNOSoxy was 4 to 9 times faster than that from the mammalian NOS enzymes. In contrast, the dNOSoxy ferrous heme-NO complex was relatively unreactive toward O2 and in this way was equivalent to the mammalian neuronal NOS. Our data show that dNOSoxy has unique settings for the kinetic parameters that determine its NO synthesis. Computer simulations reveal that these unique settings should enable dNOS to be a more efficient and active NO synthase than the mammalian NOS enzymes, which may allow it to function more broadly in cell signaling and immune functions in the fruit fly
Emergency Meningococcal ACWY Vaccination Program for Teenagers to Control Group W Meningococcal Disease, England, 2015–2016
During the first 12 months of an emergency meningococcal ACWY vaccination program for teenagers in England,
coverage among persons who left school in 2015, the first
cohort to be vaccinated, was 36.6%. There were 69% fewer group W meningococcal cases than predicted by trend analysis and no cases in vaccinated teenagers
The HST/ACS Coma Cluster Survey. II. Data Description and Source Catalogs
The Coma cluster was the target of a HST-ACS Treasury program designed for
deep imaging in the F475W and F814W passbands. Although our survey was
interrupted by the ACS instrument failure in 2007, the partially completed
survey still covers ~50% of the core high-density region in Coma. Observations
were performed for 25 fields that extend over a wide range of cluster-centric
radii (~1.75 Mpc) with a total coverage area of 274 arcmin^2. The majority of
the fields are located near the core region of Coma (19/25 pointings) with six
additional fields in the south-west region of the cluster. In this paper we
present reprocessed images and SExtractor source catalogs for our survey
fields, including a detailed description of the methodology used for object
detection and photometry, the subtraction of bright galaxies to measure faint
underlying objects, and the use of simulations to assess the photometric
accuracy and completeness of our catalogs. We also use simulations to perform
aperture corrections for the SExtractor Kron magnitudes based only on the
measured source flux and half-light radius. We have performed photometry for
~73,000 unique objects; one-half of our detections are brighter than the
10-sigma point-source detection limit at F814W=25.8 mag (AB). The slight
majority of objects (60%) are unresolved or only marginally resolved by ACS. We
estimate that Coma members are 5-10% of all source detections, which consist of
a large population of unresolved objects (primarily GCs but also UCDs) and a
wide variety of extended galaxies from a cD galaxy to dwarf LSB galaxies. The
red sequence of Coma member galaxies has a constant slope and dispersion across
9 magnitudes (-21<M_F814W<-13). The initial data release for the HST-ACS Coma
Treasury program was made available to the public in 2008 August. The images
and catalogs described in this study relate to our second data release.Comment: Accepted for publication in ApJS. A high-resolution version is
available at http://archdev.stsci.edu/pub/hlsp/coma/release2/PaperII.pd
The Triarchic Psychopathy Measure (TriPM): alternative to the PCL-R?
Psychopathic personality disorder is the subject of many research papers and in particular in the context of forensic settings, where its link to risk of future violence has been established. This topic is well examined but there is still considerable debate about the nature of the construct and how psychopathy is measured. Contemporary models such as the triarchic theory (Patrick, Fowles & Krueger, 2009) have been put forward yet the research into psychopathy tends to rely on one assessment tool, the Psychopathy Checklist-Revised (PCL-R; Hare, 2003) that is argued not to capture elements of psychopathy such as boldness. The Triarchic Psychopathy Measure (TriPM; Patrick, 2010) is a measure that is based on the triarchic theory, and it places an equal focus on boldness when measuring psychopathy. It is however a self-report instrument, and this approach has many limitations. This paper aims to review the scientific support for the TriPM and to discuss its potential application to clinical practice. It concludes that the TriPM may not yet be a contender for the PCL-R throne as the sole tool of choice for psychopathy measurement, but the research into the application of the TriPM is expanding our understanding of psychopathy as a construct
Biodegradable and water resistant poly(vinyl) alcohol (PVA)/starch (ST)/glycerol (GL)/halloysite nanotube (HNT) nanocomposite films for sustainable food packaging
As a novel biodegradable material, poly (vinyl) alcohol (PVA)/starch (ST)/ glycerol (GL)/halloysite nanotube (HNT) nanocomposite films were prepared by solution casting at the HNT contents of 0.25, 0.5, 1, 3, and 5 wt%. Water absorption capacity and water solubility of nanocomposite films were decreased remarkably by 44.24 and 48.05%, respectively, with increasing the HNT content from 0 to 5 wt% when compared with
those of biopolymer matrices. Moreover, the water contact angle of nanocomposite films increased by 21.36◦ with the incorporation of HNTs. The presence of HNTs appeared to reduce the overall migration rates for PVA/ST/GL/HNT nanocomposite films when interacting with either hydrophilic or lipophilic food simulants. However, the migration
rates of HNTs alone were enhanced with increasing the HNT content in hydrophilic, lipophilic, and acidic food simulants. On the other hand, the biodegradation rate and light transmittance of nanocomposite films were reduced linearly by 18.56 and 26.90% with increasing the HNT content from 0 to 5 wt%. Overall, novel PVA/ST/GL/HNT nanocomposite films in this study offer highly competitive materials with excellent water resistance, good biodegradability, and acceptable transparency to be potentially used for sustainable food packaging particularly targeting lipophilic and acidic foodstuffs
Cloning whole bacterial genomes in yeast
Most microbes have not been cultured, and many of those that are cultivatable are difficult, dangerous or expensive to propagate or are genetically intractable. Routine cloning of large genome fractions or whole genomes from these organisms would significantly enhance their discovery and genetic and functional characterization. Here we report the cloning of whole bacterial genomes in the yeast Saccharomyces cerevisiae as single-DNA molecules. We cloned the genomes of Mycoplasma genitalium (0.6 Mb), M. pneumoniae (0.8 Mb) and M. mycoides subspecies capri (1.1 Mb) as yeast circular centromeric plasmids. These genomes appear to be stably maintained in a host that has efficient, well-established methods for DNA manipulation
Retention of Memory through Metamorphosis: Can a Moth Remember What It Learned As a Caterpillar?
Insects that undergo complete metamorphosis experience enormous changes in both morphology and lifestyle. The current study examines whether larval experience can persist through pupation into adulthood in Lepidoptera, and assesses two possible mechanisms that could underlie such behavior: exposure of emerging adults to chemicals from the larval environment, or associative learning transferred to adulthood via maintenance of intact synaptic connections. Fifth instar Manduca sexta caterpillars received an electrical shock associatively paired with a specific odor in order to create a conditioned odor aversion, and were assayed for learning in a Y choice apparatus as larvae and again as adult moths. We show that larvae learned to avoid the training odor, and that this aversion was still present in the adults. The adult aversion did not result from carryover of chemicals from the larval environment, as neither applying odorants to naïve pupae nor washing the pupae of trained caterpillars resulted in a change in behavior. In addition, we report that larvae trained at third instar still showed odor aversion after two molts, as fifth instars, but did not avoid the odor as adults, consistent with the idea that post-metamorphic recall involves regions of the brain that are not produced until later in larval development. The present study, the first to demonstrate conclusively that associative memory survives metamorphosis in Lepidoptera, provokes intriguing new questions about the organization and persistence of the central nervous system during metamorphosis. Our results have both ecological and evolutionary implications, as retention of memory through metamorphosis could influence host choice by polyphagous insects, shape habitat selection, and lead to eventual sympatric speciation
- …