Effect of resonance frequency, power input, and saturation gas type on the oxidation efficiency of an ultrasound horn

The sonochemical oxidation efficiency (eta(ox)) of a commercial titanium alloy ultrasound horn has been measured using potassium iodide as a dosimeter at its main resonance frequency (20 kHz) and two higher resonance frequencies (41 and 62 kHz). Narrow power and frequency ranges have been chosen to minimise secondary effects such as changing bubble stability, and time available for radical diffusion from the bubble to the liquid. The oxidation efficiency, eta(ox), is proportional to the frequency and to the power transmitted to the liquid (275 mL) in the applied power range (1-6 W) under argon. Luminol radical visualisation measurements show that the radical generation rate increases and a redistribution of radical producing zones is achieved at increasing frequency. Argon, helium, air, nitrogen, oxygen, and carbon dioxide have been used as saturation gases in potassium iodide oxidation experiments. The highest eta(ox) has been observed at 5 W under air at 62 kHz. The presence of carbon dioxide in air gives enhanced nucleation at 41 and 62 kHz and has a strong influence on eta(ox). This is supported by the luminol images, the measured dependence of eta(ox). on input power, and bubble images recorded under carbon dioxide. The results give insight into the interplay between saturation gas and frequency, nucleation, and their effect on eta(ox). (C) 2010 Elsevier B.V. All rights reserved.

Transmetalation reactions with nitrogen-containing

The transmetalation reaction of the aryllithium compound [Li(NCN)](2) (NCN is the monoanionic

Cycloalkenyl Halide Substitution Reactions of Enantiopure Arene cis-Tetrahydrodiols with Boron, Nitrogen and Phosphorus Nucleophiles

Enantiopure arene cis-tetrahydrodiols of bromobenzene and iodobenzene have been obtained in good yields, from chemoselective hydrogenation (rhodium-graphite) of the corresponding cis-dihydrodiol metabolites. Palladium-catalysed substitution of the halogen, by hydrogen, boron, nitrogen and phosphorus nucleophiles, in the acetonide derivatives, has yielded highly functionalised products for application in synthesis with potential as scaffolds for chiral ligands.

Altered stress stimulation of inward rectifier potassium channels in Andersen-Tawil syndrome

Inward rectifier potassium channels of the Kir2 subfamily are important determinants of the electrical activity of brain and muscle cells. Genetic mutations in Kir2.1 associate with Andersen-Tawil syndrome (ATS), a familial disorder leading to stress-triggered periodic paralysis and ventricular arrhythmia. To identify the molecular mechanisms of this stress trigger, we analyze Kir channel function and localization electrophysiologically and by time-resolved confocal microscopy. Furthermore, we employ a mathematical model of muscular membrane potential. We identify a novel corticoid signaling pathway that, when activated by glucocorticoids, leads to enrichment of Kir2 channels in the plasma membranes of mammalian cell lines and isolated cardiac and skeletal muscle cells. We further demonstrate that activation of this pathway can either partly restore (40% of cases) or further impair (20% of cases) the function of mutant ATS channels, depending on the particular Kir2.1 mutation. This means that glucocorticoid treatment might either alleviate or deteriorate symptoms of ATS depending on the patient's individual Kir2.1 genotype. Thus, our findings provide a possible explanation for the contradictory effects of glucocorticoid treatment on symptoms in patients with ATS and may open new pathways for the design of personalized medicines in ATS therapy. © FASEB.

The VLT-FLAMES survey of massive stars: Nitrogen abundances for Be-type stars in the Magellanic Clouds

Aims. We compare the predictions of evolutionary models for early-type stars with atmospheric parameters, projected rotational velocities and nitrogen abundances estimated for a sample of Be-type stars. Our targets are located in 4 fields centred on the Large Magellanic Cloud cluster: NGC 2004 and the N 11 region as well as the Small Magellanic Cloud clusters: NGC 330 and NGC 346.

Population pharmacokinetic model of canrenone after intravenous administration of potassium canrenoate to paediatric patients

Objectives: To characterize the population pharmacokinetics of canrenone following administration of potassium canrenoate in paediatric patients. Patients and Methods: Data were collected prospectively from 23 paediatric patients (2 days to 10 years of age; median weight 4 kg, range 2.16-28.0 kg) who received intravenous potassium canrenoate (K-canrenoate) as part of their intensive care therapy for removal of retained fluids e.g. in pulmonary oedema due to chronic lung disease and for the management of congestive heart failure. Plasma samples were analysed by HPLC for determination of canrenone (the major metabolite and pharmacologically active moiety) and the data subjected to pharmacokinetic analysis using NONMEM. Results: A one-compartment model best described the data. The only significant covariate was weight (WT). The final population models for canrenone clearance (CL/F) and volume of distribution (V/F) were CL/F (L/hr) = 11.4 × (WT /70.0)(0.75) and V/F (L) = 374.2 × (WT/70) where WT is in kg. The values of CL/F and V/F in a 4 kg child would be 1.33 L/hr and 21.4 L, respectively, resulting in an elimination half-life of 11.2 hr. Conclusions: The range of estimated CL/F in the study population was 0.67-7.38 L/hr. The data suggest that adjustment of K-canrenoate dosage according to body weight is appropriate in paediatric patients

Increasing the accuracy of Nitrogen Dioxide (NO2) pollution mapping using geographically weighted regression (GWR) and geostatistics.

Nitrogen Dioxide (NO2) is known to act as an environmental trigger for many respiratory illnesses. As a pollutant it is difficult to map accurately, as concentrations can vary greatly over small distances. In this study three geostatistical techniques were compared, producing maps of NO2 concentrations in the United Kingdom (UK). The primary data source for each technique was NO2 point data, generated from background automatic monitoring and background diffusion tubes, which are analysed by different laboratories on behalf of local councils and authorities in the UK. The techniques used were simple kriging (SK), ordinary kriging (OK) and simple kriging with a locally varying mean (SKlm). SK and OK make use of the primary variable only. SKlm differs in that it utilises additional data to inform prediction, and hence potentially reduces uncertainty. The secondary data source was Oxides of Nitrogen (NOx) derived from dispersion modelling outputs, at 1km x 1km resolution for the UK. These data were used to define the locally varying mean in SKlm, using two regression approaches: (i) global regression (GR) and (ii) geographically weighted regression (GWR). Based upon summary statistics and cross-validation prediction errors, SKlm using GWR derived local means produced the most accurate predictions. Therefore, using GWR to inform SKlm was beneficial in this study.