70 research outputs found
Cognitive behavioural therapy for insomnia in patients with rheumatoid arthritis:protocol for the randomised, single-blinded, parallel-group Sleep-RA trial
Comparison of codes assessing galactic cosmic radiation exposure of aircraft crew
The assessment of the exposure to cosmic radiation onboard aircraft is one of the preoccupations of bodies responsible for radiation protection. Cosmic particle flux is significantly higher onboard aircraft than at ground level and its intensity depends on the solar activity. The dose is usually estimated using codes validated by the experimental data. In this paper, a comparison of various codes is presented, some of them are used routinely, to assess the dose received by the aircraft crew caused by the galactic cosmic radiation. Results are provided for periods close to solar maximum and minimum and for selected flights covering major commercial routes in the world. The overall agreement between the codes, particularly for those routinely used for aircraft crew dosimetry, was better than ±20 % from the median in all but two cases. The agreement within the codes is considered to be fully satisfactory for radiation protection purpose
Morphological and Geochemical Evidence of Eumelanin Preservation in the Feathers of the Early Cretaceous Bird, Gansus yumenensis
Recent studies have shown evidence for the preservation of colour in fossilized soft tissues by imaging melanosomes, melanin pigment containing organelles. This study combines geochemical analyses with morphological observations to investigate the preservation of melanosomes and melanin within feathers of the Early Cretaceous bird, Gansus yumenensis. Scanning electron microscopy reveals structures concordant with those previously identified as eumelanosomes within visually dark areas of the feathers but not in lighter areas or sedimentary matrices. Fourier transform infrared analyses show different spectra for the feathers and their matrices; melanic functional groups appear in the feather including carboxylic acid and ketone groups that are not seen in the matrix. When mapped, the carboxylic acid group absorption faithfully replicates the visually dark areas of the feathers. Electron Paramagnetic Resonance spectroscopy of one specimen demonstrates the presence of organic signals but proved too insensitive to resolve melanin. Pyrolysis gas chromatography mass spectrometry shows a similar distribution of aliphatic material within both feathers that are different from those of their respective matrices. In combination, these techniques strongly suggest that not only do the feathers contain endogenous organic material, but that both geochemical and morphological evidence supports the preservation of original eumelanic pigment residue
Wall fluxes of reactive oxygen species of an rf atmospheric-pressure plasma and their dependence on sheath dynamics
This article was published in the serial, Journal of Physics D: Applied Physics [© IOP Publishing Ltd]. The definitive version is available at: http://dx.doi.org/10.1088/0022-3727/45/30/305205A radio-frequency (rf) atmospheric-pressure discharge in He–O2 mixture is studied using a
fluid model for its wall fluxes and their dependence on electron and chemical kinetics in the
sheath region. It is shown that ground-state O, O+2 and O− are the dominant wall fluxes of
neutral species, cations and anions, respectively. Detailed analysis of particle transport shows
that wall fluxes are supplied from a boundary layer of 3–300μm immediately next to an
electrode, a fraction of the thickness of the sheath region. The width of the boundary layer
mirrors the effective excursion distance during lifetime of plasma species, and is a result of
much reduced length scale of particle transport at elevated gas pressures. As a result, plasma
species supplying their wall fluxes are produced locally within the boundary layer and the
chemical composition of the overall wall flux depends critically on spatio-temporal
characteristics of electron temperature and density within the sheath. Wall fluxes of cations
and ions are found to consist of a train of nanosecond pulses, whereas wall fluxes of neutral
species are largely time-invariant
Inhibitory effect of Actinidia arguta on mutagenesis, inflammation and two-stage mouse skin tumorigenesis
Influence of the form of felling and the manners of soil preparation on the content of heavy metals in the leaves of trees
Influence of full plowing upon the content of some heavy metals in soils of an industrial region
Temperature influence on properties of hydroxyapatite nanoparticles synthesized in lecithin-based wet chemical precipitation
Badania dotyczyły otrzymywania nanocząstek hydroksyapatytu metodą chemicznej precypitacji w obecności lecytyny w różnych temperaturach procesu w reaktorze półokresowym. Otrzymano kuliste cząstki o rozmiarze 100 nm i powierzchniowym potencjale zeta około 0 mV. Te właściwości nie zależą od temperatury. Analiza chemiczna produktu wykazała natomiast wpływ temperatury na obecność lecytyny w produkcie precypitacji. Zjawisko to będzie przedmiotem dalszych badań, w celu określenia dokładnego stężenia lecytyny w nanocząstkach hydroksyapatytu modyfikowanego lecytyną.Hydroxyapatite nanopaiticles preparation using lecithin-based wet chemical precipitation process in different temperatures in a semi-batch reactor was investigated. Particles characterized by spherical shape of about 100 nm size and surface zeta potential of about 0 mV were obtained. Precipitation temperature did not affect these properties of nanopaiticles. Chemical analysis showed the influence of precipitation temperature on lecithin presence in precipitation products. The phenomenon of lecithin presence and concentration in hydroxyapatite nanopaiticles will be investigated in further research
Synthesis of hydroxyapatite in a continuous reactor : a review
Because of excellent properties, similar to natural bone minerals, and variety of possible biomedical applications, hydroxyapatite (HAp) is a valuable compound among the calcium phosphate salts. A number of synthesis routes for producing HAp powders have been reported. Despite this fact, it is important to develop new methods providing precise control over the reaction and having potential to scale-up. The main motivation for the current paper is a view of continuous synthesis methods toward medical application of produced hydroxyapatite, especially in the form of nanoparticles
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