An acoustic shadowgraph trial to detect convection in the Arctic

The EU Framework 5 project CONVECTION aims to understand convection processes in the Greenland Sea. By studying water motion close to the surface we hope to determine how convection is linked to atmospheric conditions and local surface features.

The usual methods of studying such processes in the ocean are by taking multiple soundings of conductivity, temperature and pressure or towing a large chain measuring temperature and salinity through a cross-section of ocean. These have the disadvantage of yielding information only while the research vessel is in the area. We have employed an alternative acoustic method that can provide data for long periods using semi-permanent moorings.

The acoustic shadowgraph method relies on the fact that when an acoustic signal propagates through a region containing convective irregularities the temperature variations along the path cause the signal amplitude to fluctuate. Unlike tomography, the shadowgraph does not require travel times to be measured and so the equipment can be much cheaper.

This paper describes the experimental apparatus, its testing and deployment on Vesteris Bank in the Greenland Sea in October 2001 and its recovery in April 2002. It also gives an overview of some of the acoustic intensity results and shows how they can be interpreted to yield estimates of sub-surface convection velocities.     

FeII Spin‐Crossover Phenomenon in the Pentadecanuclear {Fe9[Re(CN)8]6} Spherical Cluster

The self‐assembly of iron(II) ions with rare octacyanidorhenate(V) metalloligands in a methanolic solution results in the formation of a nanometric pentadecanuclear {Fe^II₉[Re^V(CN)₈]₆(MeOH)₂₄}?10 MeOH ( 1 ) molecule with a six‐capped body‐centered cubic topology. The cluster demonstrates a thermally‐induced spin‐crossover phase transition at T_1/2=195 K which occurs selectively for a single Fe^II ion embedded in the center of a cluster core.     

How to use thermal imaging in venous insufficiency?

This paper is intended to provide studies performed on usefulness of thermal imaging for the insufficiency of superficial veins in the lower limbs. The results are a continuation of the previous research and show a new way of analysis and better correlation between standard methods of parameters like duplex ultrasonography and parameters derived from thermal imaging. In particular promised seems to be using the mean whole limb temperature of healthy volunteers at a proper age as a threshold to count the isotherm area, and in isotherm analysis should be taken for the whole lower limb—the sum of thermal images from anterior and posterior views (Method II). The study was performed by the use of a Thermovision E60 camera by Flir Systems. All studies (duplex ultrasonography as well as thermal imaging) were performed in a research room with a stabilized temperature on two groups of patients, a group of healthy people and patients suffering from chronic venous disease. During the study, the correlation parameters were obtained with ultrasound and thermal parameters. The results showed that temperature changes observed in the lower extremities of the thermal skin map are associated with a healthy state of blood supply which might be connected with blood stasis, inflammatory states and swelling that occurs in the soft tissues. We found the mean and higher correlations between thermal and ultrasound parameters, for example, a good positive correlation (r = 0.63) between the thermal range to the total limb length radio and the range of reflux was obtained. The correlation between thermal imaging parameters and duplex ultrasound parameters may show that thermovision is an extremely promising method, and it can be useful in the screening of diagnosis of superficial vein insufficiency.     

Thermovision diagnostics in chosen spine diseases treated by whole body cryotherapy

The non-invasive infrared technique was used in case of the thermal imaging of patients suffering from spine diseases. Measurements were performed for the group of 50 patients during whole body cryotherapy at the second, fifth and tenth day of the rehabilitation cycle. An enhancement of the profile of skin temperature due to body cooling caused an increase in the diagnostic sensitivity of thermovision. The temperature parameters such as temperature contrast (ΔT = T _max ? T _min) and relative change of contrast ratio defined as (ΔT)/(T _mean) in the region of interest (ROI’s) were used to point out differences between the healthy patients and patients suffering from ankylosing spondylitis, sciatica and spondyloarthrosis. The value of the thermovision diagnostic in the case of spine diseases was confirmed by statistical analysis.     

Thermal annealing effects in LiF crystals implanted with57Fe ions

Thermal annealing effects in lithium fluoride single crystals implanted with⁵⁷Fe ions were studied by conversion electron Mössbauer spectroscopy. It was found that annealing in vacuum leads mostly to the precipitation of metallic aggregates in contrast to the annealing in He and H₂ when the formation of ferric compounds, having high magnetic transition temperatures, takes place.     

Dielectric Relaxation and Quasielastic Neutron Scattering Study of Molecular Reorientation in the Nematic and Solid Phases of 4,4'-Di-N-Butyloxyazoxybenzene

Dielectric relaxation measurements carried out in the nematic phae of 4,4'-di-n-butyloxyazoxybenzene (BOAOB) reveal fast reorientational motions of the whole molecule around the long axis (τ₁ ∼ 60 ps) as well as slow reorientational motions of the whole molecule around the short axis (τ₁ ∼ 10^-8 s). Incoherent quasielastic neutron scattering spectra obtained for nematic BOAOB, with normal and deuteriated alkoxy terminals, are interpreted as dominated by reorientation (around the C-N bonds) of moieties consisting of benzene rings coupled with alkoxy terminal chains (τ₁ ∼ 4ps). In addition fast conformational changes occur in these chains. Dielectric relaxation measurements reveal librations of the whole molecule in the crystal phases CI and CII accompanied by reorientation of the terminal chains in these phases. The reorientations occur on the time scale amounting to 10^-8 s. Incoherent quasielastic neutron scattering spectra obtained for the CI and CII phases of BOAOB are interpreted as being dominated by overdamped librational motions of the moieties accompanied by fast conformational changes in the alkyl chains. The CIII phase corresponds to a normal molecular crystal.     

High performance ion exclusion chromatographic characterization of the vaginal organic acids in women with bacterial vaginosis.

Vaginal organic acids have previously been detected by gas-liquid chromatography, but we have applied an ion exclusion high performance liquid chromatographic procedure to the analysis of vaginal discharge samples. This procedure has the advantage of not requiring derivitization of non-volatile acids and provides the convenience of a technique which does not require the use of flammable gasses, while allowing the identification of at least 18 different acids from the same chromatographic analysis. Vaginal discharge from women with symptoms of bacterial vaginosis was collected on weighed swabs and analysed for the presence of organic acids. The results were compared to the organic acid content of samples obtained from the same cohort of women after treatment with metronidazole. In addition, samples were obtained from asymptomatic women and these samples were analysed in the same manner. The number of organic acids present in samples from women with bacterial vaginosis was greater than the number found after treatment or among asymptomatic women. Succinic acid appeared to be inversely related to lactate concentration and succinate:lactate ratios were greater among women with bacterial vaginosis before treatment than after treatment. Liquid chromatography has proven useful as a means of evaluating the metabolic end-products of vaginal microorganisms in situ.     

Temperature-dependent hyperfine parameters in CaFeSi2O6

Two samples of natural hedenbergite CaFeSi₂O₆ were studied in the temperature range from 4.2 K to 295 K, and at 78 K and 295 K in magnetic fields from 4.5 T to 7.5 T. The sign of V_ZZ is positive at 4.2 and 78 K and negative at 295 K. The asymmetry parameter depends strongly on the temperature. These results are explained by a simple model assuming a nondegenerated orbital doublet as ground state of Fe²⁺.