172 research outputs found
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Vanadium interaction with FCC catalysts
Fluidised cracking catalysts, which contain a form of zeolite-Y as the main catalytically active component, are widply used commercially for the conversion of crude oil into more profitable product streams. During the cracking reaction, these catalysts are contaminated with vanadium which has a marked effect on the crystallinity of the zeolite-Y component and, as a consequence, activity and selectivity for hydrocarbon processing is degraded. The purpose of this work has been to carry out a detailed investigation, on the laboratory scale, of the effect of vanadium contaminatioil on both commercial and model rare earth ion-exchanged zeolite-Y catalysts. Vanadium contamination was achieved using a standard (Mitchell) method and catalysts were subject to treatment conditions similar to those found in the regenerator part of a fluidised catalytic cracking unit using a specially constructed furnace. Investigations of the solid state chemical reactions between vanadium and rare earth compounds, both in the presence and absence of silica and alumina support materials typical of those found in commercial catalysts, extend the study. Extensive use is made of magic-angle-spinning nuclear magnetic resonance spectroscopy (51V and 27Al), X-ray powder diffraction and surface area measurements for sample characterisation. The apparatus for surface area measurements was constructed during the course of the work.
It is suggested that the reduction in crystallinity of rare earth ion-exchanged zeolite-Y in the presence of vanadium is associated with the removal of rare earth ions from the cage structure of the zeolite. The extent of this process depends upon the details of the treatment conditions and important factors are identified. The observation of the formation of LaVO4 in a range of hydrothermally treated lanthanum ion-exchanged zeolite-Y samples supports the proposed model
Geocheinical studies of sediments from the gulf of paria, venezuela; and the Atlantic ocean north of the Faeroe islands
Section 1 is concerned with the geochemistry of sub-samples taken from a suite of 5 piston cores collected over the southern part of the Iceland-Faeroes Rise in the North Atlantic Ocean. The samples were taken in 1968 during Cruise No. 14 of the R.V. Meteor of the Deutsches Hydrographisches Institut. The Iceland-Faeroes Rise appears to have acted as a barrier, resulting in a high proportion of terrigenous material in the sediment accumulating on the eastern side. The sediment east of the Rise contains a relatively high proportion of material derived from a source area which includes metamorphic rocks. True marine sedimentation, i.e., precipitation of CaC0(_3), becomes important in the stations west of the Rise. Iceland appears to have overprinted the sediments by the introduction of volcanic glass, the greater proportion of which occurs in the cores east of the Rise. The distribution of volcanic debris may have resulted in part from the prevailing westerly winds. Bottom currents flowing westwards over the Rise appear to have carried either the fine fraction of the volcanic glass or its alteration products into the Atlantic Basin. Section 2 deals with the geochemistry and mineralogy of a suite of sediment samples collected from the Boca Vagre estuary on the southern margin of the Gulf of Paria. These sediments were collected in 1963 during Cruise 55 of the R.V. Chain, of Woods Hole Oceanographic Institution. Variation in the major element geochemistry and mineralogy are studied in the light of earlier works on the geochemistry and sedimentation rates in the area. The results indicate a distinct change in sedimentation over the pro-delta region, which is reflected in the amount of resistant material in the sediment, and also in the amount, and possibly the composition of the hydrolysate fraction. Variations in pH, and sedimentation rate noted by earlier workers, are reflected in the carbonate content, which shoves an increase out into the Gulf. Changes observed in the minor element population are consistent with an increase in the content of the hydrolysate fraction. The proportion of illite and montmorillonite in the hydrolysate fraction would appear to be constant, from evidence provided by the results of Factor Analysis
Diva over Divine: Towards a Historically Informed Performance of the Sacred Solo Motet in Early-Eighteenth Century Venice
In preparation for a performance, a musician may ask “how was it performed?”; “how could it be performed?”; “Can I perform it in a similar way to...?”. For singers wishing to perform the music for solo voice heard in the sacred institutions of early-eighteenth century Italy, the questions are left unanswered. In the broad field of vocal performance practice, the corner in which eighteenth-century sacred vocal music stands remains in shadow. Histories of eighteenth-century music skim the surface of sacred repertoire and leave the genres, and their performance, undisturbed. Those that do illumine the sections of this rich history often stay at the surface and write overviews of a genre in a location. A lack of study has left much repertoire neglected and so modern performers lack the knowledge to access the repertoire and realise it in performances. In a bid to suggest answers to the questions of a performer, I have chosen to investigate the performance of the solo motet in the context of sacred 1720-50s Venice.
This thesis explores the position of the solo motet genre in early eighteenth-century Venice, it’s role as a point of intersection between the secular and sacred musical spheres and seeks to answer the question: would the performance of a sacred solo motet employ the same performance practice as that of a secular cantata or operatic aria? Specifically, I explain how the solo motet interacted with Venice’s social, political and musical contexts. I place the solo motet as a vehicle for secular vocal performance practice in the churches of the Venetian ospedali. This acts as context for a case study which focuses on the Motetto a voce sola con instrumenti by Nicola Porpora for Graziosa in 1744. To form an idea of the performance practice employed by the original soloist, I will evaluate the vocal tuition received by the members of the figlie del cori, and the practice this facilitated, and the popular performance practice discussed in the treatises of Pier Francesco Tosi and Giocomo Mancini. I will compare the employment of virtuosic ornamentation in the solo motet to contemporary secular opera arias and cantatas. This thesis will be drawn to conclusion with a historically informed performance edition of the first aria of the solo motet
Diva over Divine: Towards a Historically Informed Performance of the Sacred Solo Motet in Early-Eighteenth Century Venice
In preparation for a performance, a musician may ask “how was it performed?”; “how could it be performed?”; “Can I perform it in a similar way to...?”. For singers wishing to perform the music for solo voice heard in the sacred institutions of early-eighteenth century Italy, the questions are left unanswered. In the broad field of vocal performance practice, the corner in which eighteenth-century sacred vocal music stands remains in shadow. Histories of eighteenth-century music skim the surface of sacred repertoire and leave the genres, and their performance, undisturbed. Those that do illumine the sections of this rich history often stay at the surface and write overviews of a genre in a location. A lack of study has left much repertoire neglected and so modern performers lack the knowledge to access the repertoire and realise it in performances. In a bid to suggest answers to the questions of a performer, I have chosen to investigate the performance of the solo motet in the context of sacred 1720-50s Venice.
This thesis explores the position of the solo motet genre in early eighteenth-century Venice, it’s role as a point of intersection between the secular and sacred musical spheres and seeks to answer the question: would the performance of a sacred solo motet employ the same performance practice as that of a secular cantata or operatic aria? Specifically, I explain how the solo motet interacted with Venice’s social, political and musical contexts. I place the solo motet as a vehicle for secular vocal performance practice in the churches of the Venetian ospedali. This acts as context for a case study which focuses on the Motetto a voce sola con instrumenti by Nicola Porpora for Graziosa in 1744. To form an idea of the performance practice employed by the original soloist, I will evaluate the vocal tuition received by the members of the figlie del cori, and the practice this facilitated, and the popular performance practice discussed in the treatises of Pier Francesco Tosi and Giocomo Mancini. I will compare the employment of virtuosic ornamentation in the solo motet to contemporary secular opera arias and cantatas. This thesis will be drawn to conclusion with a historically informed performance edition of the first aria of the solo motet
Macrophage-derived insulin-like growth factor-1 is a key neurotrophic and nerve-sensitizing factor in pain associated with endometriosis
Endometriosis is a common incurable inflammatory disorder that is associated with debilitating pelvic pain in women. Macrophages are central to the pathophysiology of endometriosis: they dictate the growth and vascularization of endometriosis lesions and more recently have been shown to promote lesion innervation. The aim of this study was to determine the mechanistic role of macrophages in producing pain associated with endometriosis. Herein, we show that macrophage depletion in a mouse model of endometriosis can reverse abnormal changes in pain behavior. We identified that disease-modified macrophages exhibit increased expression of IGF-1 in an in vitro model of endometriosis-associated macrophages and confirmed expression by lesion-resident macrophages in mice and women. Concentrations of IGF-1 were elevated in peritoneal fluid from women with endometriosis and positively correlate with their pain scores. Mechanistically, we demonstrate that macrophage-derived IGF-1 promotes sprouting neurogenesis and nerve sensitization in vitro. Finally, we show that the Igf-1 receptor inhibitor linsitinib reverses the pain behavior observed in mice with endometriosis. Our data support a role for macrophage-derived IGF-1 as a key neurotrophic and sensitizing factor in endometriosis, and we propose that therapies that modify macrophage phenotype may be attractive therapeutic options for the treatment of women with endometriosis-associated pain.—Forster, R., Sarginson, A., Velichkova, A., Hogg, C., Dorning, A., Horne, A. W., Saunders, P. T. K., Greaves, E. Macrophage-derived insulin-like growth factor-1 is a key neurotrophic and nerve-sensitizing factor in pain associated with endometriosis
Intelligence in offspring born to women exposed to intimate partner violence: a population-based cohort study
Background: Intimate partner violence (IPV) is a risk factor for developmental problems in offspring. Despite a high prevalence of IPV in the UK and elsewhere, the longer-term outcomes of offspring born to exposed mothers remain under-researched. Methods: Population-based cohort study. We assessed IPV prevalence by type and timing for 3,153 mother-child pairs with complete data within our study population and examined associations between IPV and offspring IQ. We used multiple-imputation to evaluate bias due to our exclusion of observations with missing covariate data. Results: Nearly one in five mothers reported IPV during the study period, with 17.6% reporting emotional violence and 6.8% reporting physical violence. Taking into account potential confounders, the IQ scores of children born to mothers exposed to physical violence remained lower than those of maternally unexposed children (full-scale IQ = −2.8 points [95%CI −4.9 to −0.7], verbal IQ = −2.2 [95%CI −4.4 to −0.1], performance IQ = −2.7 [95%CI −5.0 to −0.5]) and odds of below-average intelligence (IQ<90) remained increased for full-scale (OR 1.48 [95%CI 1.03 to 2.14] and performance IQ (OR 1.48 [95%CI 1.08 to 2.04]) but not verbal IQ (OR 1.06 [95%CI 0.69 to 1.64]). Most physical violence occurred postnatally, and relative odds were most substantial when mothers were exposed to violence across pre-/perinatal and postnatal study periods (OR performance IQ<90 = 2.97 [95%CI 1.30 to 6.82]). Conclusions: Maternal exposure to physical IPV is associated with lower offspring IQ at age 8. Associations persisted after adjusting for potential confounders and were driven by violence occurring postnatally
The management of small area burns and unexpected post-burn illness in children under five years of age - A costing study in the English healthcare setting
The objective of this economic study was to evaluate the resource use and cost associated with the management of small area burns, including the additional costs associated with unexpected illness after burn in children of less than five years of age. This study was conducted as a secondary analysis of a multi-centre prospective observational cohort study investigating the physiological response to burns in children. 452 children were included in the economic analysis (median age = 1.60 years, 61.3% boys, median total burn surface area [TBSA] = 1.00%) with a mean length of stay of 0.69 days. Of these children, 21.5% re-presented to medical care with an unexpected illness within fourteen days of injury.
The cost of managing a burn of less than 10% TBSA in a child less than five years of age was £785. The additional cost associated with the management of illness after burn was £1381. A generalised linear regression model was used to determine the association between an unexpected illness after burn, presenting child characteristics and NHS cost. Our findings may be of value to those planning economic evaluations of novel technologies in burn care
Genetic and migratory evidence for sympatric spawning of tropical pacific eels from Vanuatu
The spawning areas of tropical anguillid eels in the South Pacific are poorly known, and more information about their life histories is needed to facilitate conservation. We genetically characterized 83 out of 84 eels caught on Gaua Island (Vanuatu) and tagged 8 eels with pop-up satellite transmitters. Based on morphological evidence, 32 eels were identified as Anguilla marmorata, 45 as A. megastoma and 7 as A. obscura. Thirteen of these eels possessed a mitochondrial DNA sequence (control region, 527 bp) or nuclear haplotype (GTH2b, 268 bp) conflicting with their species designation. These individuals also had multi-locus genotypes (6 microsatellite loci) intermediate between the species, and 9 of these eels further possessed heterozygote genotypes at species-diagnostic nuclear single nucleotide polymorphisms (SNPs). We classified these individuals as possibly admixed between A. marmorata and A. megastoma. One A. marmorata and one A. megastoma migrated 634 and 874 km, respectively, towards the border between the South Equatorial Current and the South Equatorial Counter Current. Both species descended from around 200 m depth at night to 750 m during the day. Lunar cycle affected the upper limit of migration depths of both species. The tags remained attached for 3 and 5 mo and surfaced <300 km from the pop-up location of a previously tagged A. marmorata. A salinity maximum at the pop-up locations corresponding to the upper nighttime eel migration depths may serve as a seamark of the spawning area. The similar pop-up locations of both species and the evidence for admixture suggest that these tropical eels share a sympatric spawning area
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