1,207 research outputs found
Effect of excess iron on oxidative dehydrogenation of 1-butene over a series of zinc ferrite catalysts
The influence of excess Fe3+ in ZnFe2O4 for the catalytic oxidative dehydrogenation of 1-butene to 1, 3-butadiene was investigated to try to clarify inconsistencies in the existing literature. A series of nanoscale zinc ferrite powders were produced with increasing Fe: Zn ratios. The materials were characterized by a range of techniques, which showed the presence of α-Fe2O3 as a distinct phase with an increasing excess of Fe3+ and SEM highlighted the increased presence of surface structures on the ferrites at higher Fe: Zn ratios. Reaction testing showed α-Fe2O3to be virtually inactive for the oxidative dehydrogenation of 1-butene. Results for the ferrite catalysts showed a significant decrease in both conversion and yield with an increasing excess of Fe3+. Therefore an excess of Fe3+ has a negative effect on catalytic activity and selectivity of zinc ferrite for the oxidative dehydrogenation of 1-butene, but acts as a promoter for competing hydrogenation and combustion side reactions
Bivariate network meta-analysis for surrogate endpoint evaluation
Surrogate endpoints are very important in regulatory decision-making in
healthcare, in particular if they can be measured early compared to the
long-term final clinical outcome and act as good predictors of clinical
benefit. Bivariate meta-analysis methods can be used to evaluate surrogate
endpoints and to predict the treatment effect on the final outcome from the
treatment effect measured on a surrogate endpoint. However, candidate surrogate
endpoints are often imperfect, and the level of association between the
treatment effects on the surrogate and final outcomes may vary between
treatments. This imposes a limitation on the pairwise methods which do not
differentiate between the treatments. We develop bivariate network
meta-analysis (bvNMA) methods which combine data on treatment effects on the
surrogate and final outcomes, from trials investigating heterogeneous treatment
contrasts. The bvNMA methods estimate the effects on both outcomes for all
treatment contrasts individually in a single analysis. At the same time, they
allow us to model the surrogacy patterns across multiple trials (different
populations) within a treatment contrast and across treatment contrasts, thus
enabling predictions of the treatment effect on the final outcome for a new
study in a new population or investigating a new treatment. Modelling
assumptions about the between-studies heterogeneity and the network
consistency, and their impact on predictions, are investigated using simulated
data and an illustrative example in advanced colorectal cancer. When the
strength of the surrogate relationships varies across treatment contrasts,
bvNMA has the advantage of identifying treatments for which surrogacy holds,
thus leading to better predictions
Effect of excess iron on oxidative dehydrogenation of 1-butene over a series of zinc ferrite catalysts
The influence of excess Fe3+ in ZnFe2O4 for the catalytic oxidative dehydrogenation of 1-butene to 1, 3-butadiene was investigated to try to clarify inconsistencies in the existing literature. A series of nanoscale zinc ferrite powders were produced with increasing Fe: Zn ratios. The materials were characterized by a range of techniques, which showed the presence of α-Fe2O3 as a distinct phase with an increasing excess of Fe3+ and SEM highlighted the increased presence of surface structures on the ferrites at higher Fe: Zn ratios. Reaction testing showed α-Fe2O3to be virtually inactive for the oxidative dehydrogenation of 1-butene. Results for the ferrite catalysts showed a significant decrease in both conversion and yield with an increasing excess of Fe3+. Therefore an excess of Fe3+ has a negative effect on catalytic activity and selectivity of zinc ferrite for the oxidative dehydrogenation of 1-butene, but acts as a promoter for competing hydrogenation and combustion side reactions
Melatonin for rapid eye movement sleep behavior disorder in Parkinson's disease : a randomised controlled trial
Background Melatonin may reduce REM-sleep behavior disorder (RBD) symptoms in Parkinson's disease (PD), though robust clinical trials are lacking. Objective To assess the efficacy of prolonged-release (PR) melatonin for RBD in PD. Methods Randomized, double-blind, placebo-controlled, parallel-group trial with an 8-week intervention and 4-week observation pre- and postintervention (ACTRN12613000648729). Thirty PD patients with rapid eye movement sleep behavior disorder were randomized to 4 mg of prolonged-release melatonin (Circadin) or matched placebo, ingested orally once-daily before bedtime. Primary outcome was the aggregate of rapid eye movement sleep behavior disorder incidents averaged over weeks 5 to 8 of treatment captured by a weekly diary. Data were included in a mixed-model analysis of variance (n = 15 per group). Results No differences between groups at the primary endpoint (3.4 events/week melatonin vs. 3.6 placebo; difference, 0.2; 95% confidence interval = -3.2 to 3.6; P = 0.92). Adverse events included mild headaches, fatigue, and morning sleepiness (n = 4 melatonin; n = 5 placebo). Conclusion Prolonged-release melatonin 4 mg did not reduce rapid eye movement sleep behavior disorder in PD. (c) 2019 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society
Synergy between the Large Synoptic Survey Telescope and the Square Kilometre Array
We provide an overview of the science benefits of combining information from
the Square Kilometre Array (SKA) and the Large Synoptic Survey Telescope
(LSST). We first summarise the capabilities and timeline of the LSST and
overview its science goals. We then discuss the science questions in common
between the two projects, and how they can be best addressed by combining the
data from both telescopes. We describe how weak gravitational lensing and
galaxy clustering studies with LSST and SKA can provide improved constraints on
the causes of the cosmological acceleration. We summarise the benefits to
galaxy evolution studies of combining deep optical multi-band imaging with
radio observations. Finally, we discuss the excellent match between one of the
most unique features of the LSST, its temporal cadence in the optical waveband,
and the time resolution of the SKA.Comment: SKA Synergies Chapter, Advancing Astrophysics with the SKA (AASKA14)
Conference, Giardini Naxos (Italy), June 9th-13th 201
ADCC Develops Over Time during Persistent Infection with Live-Attenuated SIV and Is Associated with Complete Protection against SIV(mac)251 Challenge
Live-attenuated strains of simian immunodeficiency virus (SIV) routinely confer apparent sterilizing immunity against pathogenic SIV challenge in rhesus macaques. Understanding the mechanisms of protection by live-attenuated SIV may provide important insights into the immune responses needed for protection against HIV-1. Here we investigated the development of antibodies that are functional against neutralization-resistant SIV challenge strains, and tested the hypothesis that these antibodies are associated with protection. In the absence of detectable neutralizing antibodies, Env-specific antibody-dependent cell-mediated cytotoxicity (ADCC) emerged by three weeks after inoculation with SIVDeltanef, increased progressively over time, and was proportional to SIVDeltanef replication. Persistent infection with SIVDeltanef elicited significantly higher ADCC titers than immunization with a non-persistent SIV strain that is limited to a single cycle of infection. ADCC titers were higher against viruses matched to the vaccine strain in Env, but were measurable against viruses expressing heterologous Env proteins. In two separate experiments, which took advantage of either the strain-specificity or the time-dependent maturation of immunity to overcome complete protection against SIV(mac)251 challenge, measures of ADCC activity were higher among the SIVDeltanef-inoculated macaques that remained uninfected than among those that became infected. These observations show that features of the antibody response elicited by SIVDeltanef are consistent with hallmarks of protection by live-attenuated SIV, and reveal an association between Env-specific antibodies that direct ADCC and apparent sterilizing protection by SIVDeltanef
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ADCC Develops Over Time during Persistent Infection with Live-Attenuated SIV and Is Associated with Complete Protection against Challenge
Live-attenuated strains of simian immunodeficiency virus (SIV) routinely confer apparent sterilizing immunity against pathogenic SIV challenge in rhesus macaques. Understanding the mechanisms of protection by live-attenuated SIV may provide important insights into the immune responses needed for protection against HIV-1. Here we investigated the development of antibodies that are functional against neutralization-resistant SIV challenge strains, and tested the hypothesis that these antibodies are associated with protection. In the absence of detectable neutralizing antibodies, Env-specific antibody-dependent cell-mediated cytotoxicity (ADCC) emerged by three weeks after inoculation with SIVΔnef, increased progressively over time, and was proportional to SIVΔnef replication. Persistent infection with SIVΔnef elicited significantly higher ADCC titers than immunization with a non-persistent SIV strain that is limited to a single cycle of infection. ADCC titers were higher against viruses matched to the vaccine strain in Env, but were measurable against viruses expressing heterologous Env proteins. In two separate experiments, which took advantage of either the strain-specificity or the time-dependent maturation of immunity to overcome complete protection against challenge, measures of ADCC activity were higher among the SIVΔnef-inoculated macaques that remained uninfected than among those that became infected. These observations show that features of the antibody response elicited by SIVΔnef are consistent with hallmarks of protection by live-attenuated SIV, and reveal an association between Env-specific antibodies that direct ADCC and apparent sterilizing protection by SIVΔnef
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