Remote functionalisation via sodium alkylamidozincate intermediates : access to unusual fluorenone and pyridyl ketone reactivity patterns

Treating fluorenone or 2-benzoylpyridine with the sodium zincate [(TMEDA)center dot Na(mu-Bu-t)(mu-TMP)Zn(Bu-t)] in hexane solution, gives efficient Bu-t addition across the respective organic substrate in a highly unusual 1,6-fashion, producing isolable organometallic intermediates which can be quenched and aerobically oxidised to give 3-tert-butyl-9H-fluoren-9-one and 2-benzoyl-5-tert-butylpyridine respectively

Molecular dynamics simulations of copper binding to N-terminus mutants of amyloid-β

We report results of molecular dynamic (MD) simulations on N-terminus mutants of the copper-bound, amyloid-β (Aβ) peptide. Eight structures of Aβ were modelled, including seven mutant peptides in addition to the unaltered wild-type (WT). Trajectories analysed for each individual system were all approximately 1.4 μs in length, yielding a total of over 11 μs in total. The impact of these mutations are marked and varied compared to the wild-type peptide, including effects on secondary structure, stability and conformational changes. Each system showed differing levels of stability with some showing consistent, compact conformations whereas others displayed more flexible structures. Contrasts between comparable mutations at similar sites, such as A2T/A2V and D7H/D7N, show the location as well as the type of mutation have effects on protein structure observed in Ramachandran plots. We also report notable changes in peptide structure at residues remote to the site of substitution showing these mutations influence the entirety of Aβ. Salt-bridge profiles show this most clearly: addition or removal of charged residues affecting all salt-bridge interactions present in WT, even those remote from the site of mutation. Effects on secondary structure differ between mutations, most notably a change in incidence of β-strand, which has been linked to enhanced aggregational properties for the peptide. GFN2-xTB semi-empirical calculations show clear differences in binding energies of the copper-centre for each system

The environment power system analysis tool development program

The Environment Power System Analysis Tool (EPSAT) is being developed to provide space power system design engineers with an analysis tool for determining system performance of power systems in both naturally occurring and self-induced environments. The program is producing an easy to use computer aided engineering (CAE) tool general enough to provide a vehicle for technology transfer from space scientists and engineers to power system design engineers. The results of the project after two years of a three year development program are given. The EPSAT approach separates the CAE tool into three distinct functional units: a modern user interface to present information, a data dictionary interpreter to coordinate analysis; and a data base for storing system designs and results of analysis

The topology of fluid flow past a sequence of cylinders

AbstractThis paper analyzes conditions under which dynamical systems in the plane have indecomposable continua or even infinite nested families of indecomposable continua. Our hypotheses are patterned after a numerical study of a fluid flow example, but should hold in a wide variety of physical processes. The basic fluid flow model is a differential equation in R2 which is periodic in time, and so its solutions can be represented by a time-1 map F:R2→R2. We represent a version of this system “with noise” by considering any sequence of maps Fn:R2→R2, each of which is ε-close to F in the C1 norm, so that if p is a point in the fluid flow at time n, then Fn(p) is its position at time n+1. We show that indecomposable continua still exist for small ε

Analysis of Johne’s disease ELISA status and associated performance parameters in Irish dairy cows

peer-reviewedBackground Infection with Mycobacterium avium subspecies paratuberculosis (MAP) has been associated with reductions in milk production in dairy cows and sub optimal fertility. The aim of this study was to highlight the production losses associated with testing MAP ELISA positive in Irish dairy cows. Secondary objectives included investigation of risk factors associated with testing MAP ELISA positive. A survey of management practices on study farms was also conducted, with examination of associations between management practices and herd MAP status. Blood samples were collected from 4188 breeding animals on 22 farms. Samples were ELISA tested using the ID Screen Paratuberculosis Indirect Screening Test. Production parameters examined included milk yield, milk fat, milk protein, somatic cell count, and calving interval. The association between MAP ELISA status and production data was investigated using multi-level mixed models. Logistic regression was used to identify risk factors for testing JD blood ELISA positive at individual cow level and to identify associations between farm management practices and herd MAP status. Results Data were available for 3528 cows. The apparent prevalence recorded was 7.4 %. Mixed model analysis revealed no statistically significant association between testing MAP ELISA positive and dairy cow production parameters. Risk factors associated with testing positive included larger sized herds being over twice more likely to test positive than smaller herds (OR 2.4 P = <0.001). Friesians were less likely to test positive relative to other breeds. A number of study farmers were engaged in management practices that have previously been identified as high risk for MAP transmission e.g., 73.1 % pooled colostrum and 84.6 % of study farmers used the calving area to house sick animals throughout the year. No significant associations however, were identified between farm management practices and herd MAP status. Conclusion No production losses were identified; however an apparent prevalence of 7.4 % was recorded. With the abolition of EU milk quotas herd size in Ireland is expanding, as herds included in this study were larger than the national average, results may be indicative of future JD levels if no JD control programmes are implemented to minimise transmission

Nonlinear aspects of the EEG during sleep in children

Electroencephalograph (EEG) analysis enables the neuronal behavior of a section of the brain to be examined. If the behavior is nonlinear then nonlinear tools can be used to glean information on brain behavior, and aid in the diagnosis of sleep abnormalities such as obstructive sleep apnea syndrome (OSAS). In this paper the sleep EEGs of a set of normal and mild OSAS children are evaluated for nonlinear behaviour. We consider how the behaviour of the brain changes with sleep stage and between normal and OSAS children.Comment: 9 pages, 2 figures, 4 table