Automatic detection of hippocampal atrophy on magnetic resonance images.

An automatic method for identifying hippocampal atrophy on magnetic resonance (MR) images obtained from patients with clinical evidence of temporal lobe epilepsy (TLE) is described. The method is based on the analysis of image intensity differences between patients and controls within a volume of interest (VOI) centred on the hippocampus. The core of the method is a fully automatic signal intensity-based inter-subject image registration technique. In particular, a global affine registration to a reference image is performed, followed by a local affine registration within the VOI. A mask produced by manual segmentation of the mean hippocampus for 30 control subjects enabled investigations to be restricted to a specified region of the VOI approximately corresponding to the hippocampus. Normal variations of hippocampal signal intensity were computed from images obtained for the 30 control subjects. The manual method of hippocampal volumetry, currently an important component of the pre-surgical evaluation of patients with clinical evidence of medically intractable TLE, is used to determine the lower 1st percentile limits of normal hippocampal volume. Hippocampi with volumes below this limit are defined as atrophic. We investigated whether the automatic method can correctly distinguish between 15 patients with significant hippocampal atrophy according to absolute volumes and a further 14 controls. ROC curves enabled evaluation of sensitivity and specificity in respect of an intensity threshold. 100% specificity is required when determining suitability of patients for neurosurgery, resulting in levels of 50% and 70% sensitivity in detecting atrophy in the right and left hippocampus, respectively. We propose that the method can be developed as an automatic screening procedure.     

Unexpected effect of the fluorine atom on the optimal ligand-to-palladium ratio in the enantioselective Pd-catalyzed allylation reaction of fluorinated enol carbonates

The enantioselective Pd-catalyzed allylation reaction of fluorinated allyl enol carbonates is presented; a key feature of this transformation is the important effect of the ligand-to-palladium ratio on the enantioselectivity of the alpha-fluoroketones, since using a ligand excess (L/Pd ratio = 1.25 : 1) led to moderate results (30-76% ee), while using a L/Pd ratio <1 : 1.67 (to as low as 1 : 4) allowed the desired products to be obtained with high enantiopurity (up to 94% ee).     

Effects of pulsed low-frequency electromagnetic fields on water characterized by light scattering techniques: role of bubbles

Well-characterized purified water was exposed for 6 h to pulsed low-frequency weak electromagnetic fields. After various time periods, nondegassed and degassed water samples were analyzed by static light scattering. Just after electromagnetic exposure (day 0), a reduction of over 20% in the maximum light scattering intensity at 488 nm wavelength in both nondegassed and degassed samples was observed. By contrast, on day 12 the difference was observed only in nondegassed water samples. The latter effect was attributed to the different geometries of the containers combined with the basic origin of the whole phenomenon due to gas bubbles present in water. By the use of dynamic light scattering, the bubble mean diameter was estimated to be around 300 nm. Our results suggest that the electromagnetic exposure acts on gas nanobubbles present in water and emphasizes the role of the gas/liquid interface. The possibility that exposure to electromagnetic fields disturbs the ionic double layer that contributes to bubble stabilization in water is discussed.     

Effects of pulsed low frequency electromagnetic fields on water using photoluminescence spectroscopy: role of bubble/water interface

The effects of a pulsed low frequency electromagnetic field were investigated on photoluminescence of well characterized water and prepared under controlled conditions (container, atmospheric, electromagnetic, and acoustic environments). When reference water samples were excited at 260 nm, two wide emission bands centered at 345 nm (3.6 eV) and 425 nm (2.9 eV) were observed. By contrast under 310 nm excitation, only one band appeared at 425 nm. Interestingly, electromagnetic treatment (EMT) induced, at both excitation wavelengths, a decrease (around 70%) in the 425 nm band relative photoluminescence intensity. However, no difference between reference and treated sample was observed in the 345 nm band. Other experiments, performed on outgassed samples (reference and treated), show that the emission bands (position, shape, intensity) under excitation at 260 nm and 310 nm were similar and close to the corresponding bands of the treated nonoutgassed samples. Similar effects were observed on photoluminescence excitation of water samples. Two excitation bands monitored at 425 nm were observed at 272 nm and 330 nm. After EMT and/or outgassing, a decrease (>60%) was observed in the intensity of these two bands. Altogether, these results indicate that electromagnetic treatment and/or outgassing decrease in a similar fashion the photoluminescence intensity in water samples. They also suggest that this effect is most likely indirectly attributed to the presence of gas bubbles in water. The possible role of hydrated ionic shell around the bubbles in the observed extraluminescence is discussed.     

Comparison between batch and column experiments to determine the surface charge properties of rutile TiO2 powder

This paper reports a comparative study of three methods for determining the surface charge and acid-base behavior of a TiO(2) rutile material. Electrophoretic mobility measurements were performed using two different batch protocols: (i) a "static" mode that consisted of immersing the rutile powder in aqueous solutions of given pH's and ionic strengths for 10 h, and (ii) a "dynamic" mode that consisted of using an automatic titrator to continuously adjust the solution pH with a contact time of 15 min. The same apparatus (a Nanosizer from Malvern) was used to measure the zeta potential of the particles in both methods. These batch experiments were next compared to the determination of the surface charge of rutile using nonlinear chromatography in column experiments. In that case, the rutile powder was compacted to enable the formation of a proper column bed. Therefore, Raman scattering and X-ray photoelectron spectra were used, as well as other physical information such as specific surface area and morphology of the particles, to verify that the rutile powder and compacted form were identical. The three approaches were then compared and discussed in relation to the acid-base behavior of the rutile material.     

High sensitivity separation and detection of heparan sulfate disaccharides

Eight Delta-disaccharide standards from heparan sulfate/heparin were derivatized with the fluorophore 4,4-difluoro-5,7- dimethyl-4-bora-3a,4a-diaza-s-indacene-3-propionic acid, hydrazide (BODIPY) via formation of a Schiff's base and separated using HPAEC on a Propac PA1 column with a linear salt gradient and isocratic 150 mM NaOH. Detection was with an in-line fluorescence detector. The standard deviation (sigma(n-1)) in retention times were 0.7-2% over nine runs. The limit of detection, was 100 fmol (100 x 10(-15)mol) of BODIPY labeled Delta-disaccharides, representing considerably improved detection compared to other fluorophore labeled derivatives and, unlike these, required no further purification steps. Separation and improved detection of BODIPY-Delta-disaccharide conjugates will assist the structural analysis of HS and the development of improved sequencing methodologies.     

Network characteristics of hydrogenated nitrile butadiene rubber networks obtained by radiation crosslinking by electron beam

The effects of high-energy radiation on hydrogenated nitrile butadiene rubber (HNBR) copolymer structure and properties were studied. Characterization by FTIR spectroscopy, swelling and mechanical measurements of irradiated and un-irradiated sample permit us to correlate the change in structure with properties. The modifications obtained are dependent on the radiation dose of the incident electron beam. FTIR spectroscopy in absorption mode shows that irradiation of HNBR first induces trans-vinylene bond formation and secondly small amounts of carbonyl (CO) groups. Moreover, more significant changes were observed with swelling method and mechanical behaviour showing the effect of crosslinking on the elastomer.