115 research outputs found

    Archived U-Pb (zircon) dates from southern New Brunswick

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    U-Pb (zircon) ages for eight samples from southern New Brunswick were determined during the early 1990's as part of a regional mapping and correlation program. Although most of the dates have been subsequently quoted in the literature through personal communications, and some preliminary isochron diagrams have been incorporated in papers, the results have not been published in their entirety. The units sampled and best estimates for their ages are the Lobster Brook Formation (554 ± 6 Ma), Leavitts Head Formation (554 ± 3 Ma), Ragged Falls Suite (553 ± 2 Ma), Mosquito Lake Road Formation (514 ± 2 Ma, maximum age), Bayswater Formation (436 ± 3 Ma), Centreton Granite (437 ± 3 Ma), felsic dyke of North Head, Grand Manan Island (396+3/-2 Ma), and Lake George Cupola, Lake George Mine (414 ± 2 Ma). RÉSUMÉ Des datations au U-Pb (à partir de zircon) de huit échantillons du Sud du Nouveau-Brunswick avaient été réalisées au début des années 90 dans le cadre d'un programme régional de cartographie et de corrélation. Même si la majorité des dates ont subséquemment été citées dans de la documentation par le biais de communications personnelles et que certains schémas isochrones préliminaires ont été incorporés dans des communications, les résultats n'ont pas été publiés dans leur intégralité. Les unités échantillonnées et leur meilleurs âges estimatifs comprennent la Formation de Lobster Brook (554 ± 6 Ma), la Formation de Leavitts Head (554 ± 3 Ma), le cortège de Ragged Falls (553 ± 2 Ma), la Formation de Mosquito Lake Road (514 ± 2 Ma, âge maximal), la Formation de Bayswater (436 ± 3 Ma), le granite de Centreton (437 ± 3 Ma), le dyke felsique de North Head, dans l'île Grand Manan (396+3/-2 Ma), et la coupole du lac George, à la mine du lac George (414 ± 2 Ma). [Traduit par la rédaction

    Mafic intrusions on Campobello Island: implications for New Brunswick - Maine correlations

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    Late Ordovician through Early Devonian units of the Passamaquoddy Bay area are interpreted to represent sequences that evolved in arc and back-arc environments. The main elements of the arc are exposed on Campobello Island and include a predominantly felsic volcanic sequence to the northeast, a sequence of intercalated turbidite and mafic volcanic rocks to the southwest, and matic dyke swarms throughout. Petrographic. geochemical, and 40Ar/39Ar studies of these rocks record episodic deformation and varying degrees of metamorphism up to lower amphibolite facies, and a protracted history of mafic magma injection from a similar source beginning in the Early Silurian. These features, combined with stratigraphic relationships and overall structural patterns, indicate a rapid transition from felsic- to mafic-dominated magmatism accompanied by radical changes in the depositional regime in the arc with time, and exposure of progressively deeper crustal levels towards the northeast within the arc. Review of the assignment of other units in the Passamaquoddy Bay region to major tectonostratigraphic bells north of Campobello Island clarifies regional correlations and provides possible additional links to Neoproterozoic basement in the area. RÉSUMÉ Les unités de l'Ordovicien superieur au Dévonicn inférieur du secteur de la baie Passamaquoddy sont interprétées comme des unités représentatives de séquences ayant évolué dans des environnements d'arc et d'arriére-arc. Les principaux éléments de de l'arc affleurent sur l'ile Campobello et component une séquence principalcment volcanofelsique au nord-est. une sequence volcanomafique/turbiditique intercalée au sud-ouest et des groupes de filons mafiques un peu panout. Des études pétrographiques. géochimiques et 40Ar/39Ar de ces roches rélèvent une déformation épisodique et des degrés divers de métamorphisme jusqu'au faciès amphibolique infèrieur, ainsi que des antécédents prolongés d'injection de magma mafique d'une source similairc à partir du Silurien inferieur. Ces particulierités conjuguécs aux relations stratigraphiques et aux configurations slructurales générates, révèlent une transition rapide d'un magmatisme à prédominance mafique a un magmatisme à prédominance mafique accompagné de changements spectaculaires dans te régime de sédimentation à l'intérieur de l'are avec le temps, ainsi qu'un affleurement de niveaux crustaux progressivement plus profonds vers le nord-est a l'intcrieur de l'are. L'examen de l'affectation des autres unités dans la region de la baie Passamaquoddy aux principals structures teconostratigraphiques au nord de l'ile Campobello clarifie les correlations régionalcs et foumit des liens supplémentaires possibles avec le socle du Protéroique supérieur du secteur. Traduit par la rédactio

    Enhancing non-domestic Passivhaus auditoria ventilation design for improved indoor environmental quality

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    Enhanced energy conservation strategies often involve tightly controlled ventilation flow rates. However, strategies that don't carefully consider ventilation rates can, in certain contexts, result in inadequate ventilation, with increased risks of poor indoor environmental quality and user acceptance. These design challenges are often exacerbated in non-domestic buildings with highly dynamic occupancy patterns. This study used computational fluid dynamics, supported by field measurements, to investigate the relationship between zonal supply air strategies and thermal comfort in the George Davies Centre, Leicester University, which is the largest non-domestic certified Passivhaus building in the UK. Ventilation strategies involving mechanical ventilation operating with heat recovery turned on and off, and natural ventilation systems were investigated in relation to their ability to maintain thermal comfort in an auditorium space characterised by high internal heat gains and tiered seating. The results show that, depending on the selected thermal comfort criterion, a thermally comfortable environment could be achieved when incoming air is in the range of 9–26°C for mechanical ventilation with heat recovery and 17–29°C for natural ventilation. These temperatures are referred to as ‘limiting operating temperatures’ in the paper. The work showed that in a temperate climate, thermal comfort could be maintained, for up to 80% of the year, using mixed mode ventilation, without space conditioning, in combination with intelligent design and control strategies. Operating in natural ventilation mode also provided increased fresh air supply capacity, a finding which is particularly relevant in the context of mitigating airborne viral transmission

    Pseudomonas aeruginosa arylsulfatase: a purified enzyme for the mild hydrolysis of steroid sulfates

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    The hydrolysis of sulfate ester conjugates is frequently required prior to analysis for a range of analytical techniques including gas chromatography-mass spectrometry (GC-MS). Sulfate hydrolysis may be achieved with commercial crude arylsulfatase enzyme preparations such as that derived from Helix pomatia but these contain additional enzyme activities such as glucuronidase, oxidase, and reductase that make them unsuitable for many analytical applications. Strong acid can also be used to hydrolyze sulfate esters but this can lead to analyte degradation or increased matrix interference. In this work, the heterologously expressed and purified arylsulfatase from Pseudomonas aeruginosa is shown to promote the mild enzyme-catalyzed hydrolysis of a range of steroid sulfates. The substrate scope of this P. aeruginosa arylsulfatase hydrolysis is compared with commercial crude enzyme preparations such as that derived from H. pomatia. A detailed kinetic comparison is reported for selected examples. Hydrolysis in a urine matrix is demonstrated for dehydroepiandrosterone 3-sulfate and epiandrosterone 3-sulfate. The purified P. aeruginosa arylsulfatase contains only sulfatase activity allowing for the selective hydrolysis of sulfate esters in the presence of glucuronide conjugates as demonstrated in the short three-step chemoenzymatic synthesis of 5α-androstane-3β,17β-diol 17-glucuronide (ADG, 1) from epiandrosterone 3-sulfate. The P. aeruginosa arylsulfatase is readily expressed and purified (0.9 g per L of culture) and thus provides a new and selective method for the hydrolysis of steroid sulfate esters in analytical sample preparation.We thank the Australian Government Anti-Doping Research Pro-gram for financial support

    Detection and metabolic investigations of a novel designer steroid: 3-chloro-17α-methyl-5α-androstan-17β-ol

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    In 2012, seized capsules containing white powder were analyzed to show the presence of unknown steroid-related compounds. Subsequent gas chromatography–mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR) investigations identified a mixture of 3α- and 3β- isomers of the novel compound; 3-chloro-17α-methyl-α-androstan-17β-ol. Synthesis of authentic reference materials followed by comparison of NMR, GC-MS and gas chromatography-tandem mass spectrometry (GC-MS/MS) data confirmed the finding of a new ‘designer’ steroid. Furthermore, in vitro androgen bioassays showed potent activity highlighting the potential for doping using this steroid. Due to the potential toxicity of the halogenated steroid, in vitro metabolic investigations of 3α-chloro-17α-methyl-α-androstan-17β-ol using equine and human S9 liver fractions were performed. For equine, GC-MS/MS analysis identified the diagnostic 3α-chloro-17α-methyl-5α-androstane-16α,17β-diol metabolite. For human, the 17α-methyl-α-androstane-3α,17β-diol metabolite was found. Results from these studies were used to verify the ability of GC-MS/MS precursor-ion scanning techniques to support untargeted detection strategies for designer steroids in anti-doping analyses.Synthesis and in vitro metabolic investigations of 3α/β-chloro-17α-methyl-5α-androstan -17β-ol was suppo rted by the Austr a-lian Research Council Linkage Grant (LP120200444) Strat egies for the detection of designer ster oids in ra cehorses

    Alternate steroid sulfation pathways targeted by LC-MS/MS 1 analysis of disulfates. Application to prenatal diagnosis of steroid synthesis disorders

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    The steroid disulfates (aka bis-sulfates) are a significant but minor fraction of the urinary steroid metabolome that have not been widely studied because major components are not hydrolyzed by the commercial sulfatases commonly used in steroid metabolomics. In early studies, conjugate fractionation followed by hydrolysis using acidified solvent (solvolysis) was used for the indirect detection of this fraction by GC–MS. This paper describes the application of a specific LC–MS/MS method for the direct identification of disulfates in urine, and their use as markers for the prenatal diagnosis of disorders causing reduced estriol production: STSD (steroid sulfatase deficiency), SLOS (Smith-Lemli-Opitz syndrome) and PORD (P450 oxidoreductase deficiency). Disulfates were detected by monitoring a constant ion loss (CIL) from the molecular di-anion. While focused on disulfates, our methodology included an analysis of intact steroid glucuronides and monosulfates because steroidogenic disorder diagnosis usually requires an examination of the complete steroid profile. In the disorders studied, a few individual steroids (as disulfates) were found particularly informative: pregn-5-ene-3β,20S-diol, pregn-5-ene-3β,21-diol (STSD, neonatal PORD) and 5α-pregnane-3β,20S-diol (pregnancy PORD). Authentic steroid disulfates were synthesized for use in this study as aid to characterization. Tentative identification of 5ξ-pregn-7-ene-3ξ,20S-diol and 5ξ-pregn-7-ene-3ξ,17,20S-triol disulfates was also obtained in samples from SLOS affected pregnancies. Seven ratios between the detected metabolites were applied to distinguish the three selected disorders from control samples. Our results show the potential of the direct detection of steroid conjugates in the diagnosis of pathologies related with steroid biosynthesis.Spanish Health National System is acknowledged for OP contract (CPII16/00027). Strategic Plan for Research and Innovation in Health (PERIS) of the Catalan government is acknowledge for OK contract (SLT002/16/00007)

    Survey of the quality of experimental design, statistical analysis and reporting of research using animals

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    For scientific, ethical and economic reasons, experiments involving animals should be appropriately designed, correctly analysed and transparently reported. This increases the scientific validity of the results, and maximises the knowledge gained from each experiment. A minimum amount of relevant information must be included in scientific publications to ensure that the methods and results of a study can be reviewed, analysed and repeated. Omitting essential information can raise scientific and ethical concerns. We report the findings of a systematic survey of reporting, experimental design and statistical analysis in published biomedical research using laboratory animals. Medline and EMBASE were searched for studies reporting research on live rats, mice and non-human primates carried out in UK and US publicly funded research establishments. Detailed information was collected from 271 publications, about the objective or hypothesis of the study, the number, sex, age and/or weight of animals used, and experimental and statistical methods. Only 59% of the studies stated the hypothesis or objective of the study and the number and characteristics of the animals used. Appropriate and efficient experimental design is a critical component of high-quality science. Most of the papers surveyed did not use randomisation (87%) or blinding (86%), to reduce bias in animal selection and outcome assessment. Only 70% of the publications that used statistical methods described their methods and presented the results with a measure of error or variability. This survey has identified a number of issues that need to be addressed in order to improve experimental design and reporting in publications describing research using animals. Scientific publication is a powerful and important source of information; the authors of scientific publications therefore have a responsibility to describe their methods and results comprehensively, accurately and transparently, and peer reviewers and journal editors share the responsibility to ensure that published studies fulfil these criteria

    UBVRI Light Curves of 44 Type Ia Supernovae

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    We present UBVRI photometry of 44 type-Ia supernovae (SN Ia) observed from 1997 to 2001 as part of a continuing monitoring campaign at the Fred Lawrence Whipple Observatory of the Harvard-Smithsonian Center for Astrophysics. The data set comprises 2190 observations and is the largest homogeneously observed and reduced sample of SN Ia to date, nearly doubling the number of well-observed, nearby SN Ia with published multicolor CCD light curves. The large sample of U-band photometry is a unique addition, with important connections to SN Ia observed at high redshift. The decline rate of SN Ia U-band light curves correlates well with the decline rate in other bands, as does the U-B color at maximum light. However, the U-band peak magnitudes show an increased dispersion relative to other bands even after accounting for extinction and decline rate, amounting to an additional ~40% intrinsic scatter compared to B-band.Comment: 84 authors, 71 pages, 51 tables, 10 figures. Accepted for publication in the Astronomical Journal. Version with high-res figures and electronic data at http://astron.berkeley.edu/~saurabh/cfa2snIa

    Post-stroke inhibition of induced NADPH oxidase type 4 prevents oxidative stress and neurodegeneration

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    Ischemic stroke is the second leading cause of death worldwide. Only one moderately effective therapy exists, albeit with contraindications that exclude 90% of the patients. This medical need contrasts with a high failure rate of more than 1,000 pre-clinical drug candidates for stroke therapies. Thus, there is a need for translatable mechanisms of neuroprotection and more rigid thresholds of relevance in pre-clinical stroke models. One such candidate mechanism is oxidative stress. However, antioxidant approaches have failed in clinical trials, and the significant sources of oxidative stress in stroke are unknown. We here identify NADPH oxidase type 4 (NOX4) as a major source of oxidative stress and an effective therapeutic target in acute stroke. Upon ischemia, NOX4 was induced in human and mouse brain. Mice deficient in NOX4 (Nox4(-/-)) of either sex, but not those deficient for NOX1 or NOX2, were largely protected from oxidative stress, blood-brain-barrier leakage, and neuronal apoptosis, after both transient and permanent cerebral ischemia. This effect was independent of age, as elderly mice were equally protected. Restoration of oxidative stress reversed the stroke-protective phenotype in Nox4(-/-) mice. Application of the only validated low-molecular-weight pharmacological NADPH oxidase inhibitor, VAS2870, several hours after ischemia was as protective as deleting NOX4. The extent of neuroprotection was exceptional, resulting in significantly improved long-term neurological functions and reduced mortality. NOX4 therefore represents a major source of oxidative stress and novel class of drug target for stroke therapy
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