Use of electroencephalography to detect Alzheimer''s disease in Down''s syndrome

Asthma is one of the most common chronic illnesses in childhood. Increases in hospitalization rates have occurred in several countries. The cumulative risk of asthma requiring medical attention was 11.7% for males and 7.0% for females aged 0-4 in Manitoba, Canada, for the cohort of children born in 1984/1985. The cumulative risk of hospitalization for males was nearly twice that of females (2.1% vs. 1.1%). Disease onset was most likely at age 1 year. The risk of rehospitalization or return physician visit for asthma increased significantly with the number of prior hospitalizations and physician visits, respectively, which may reflect both the persistence of asthma and the difficulty of developing an effective disease management strategy.     

The design of a system of adjustable superconducting plates for balancing a gradiometer

The gradiometer of a SQUID-system for measuring very small biomagnetic signals should be made as insensitive as possible to the much larger uniform background fields. The balance of a gradiometer can be improved considerably by modifying the effective area of the gradiometer loops by a system of small adjustable superconducting plates.This paper is intended as an aid for designing such a balancing system. We calculated the effective area of a gradiometer loop perpendicular to a rectangular or parallel to a circular plate. The paper contains graphs showing how large the plates have to be and where they must be placed.The calculations show that for accurate balancing the distance of a plate to the wire of a loop must be large and that the plates must be as small as possible.     

Reactivity of generated oxygen species from nitrous oxide over [Fe,Al]MFI catalysts for the direct oxidation of benzene to phenol

The catalytic performance of various steam-activated [Fe,Al]MFI catalysts in the direct oxidation of benzene to phenol using N₂O as oxidant is described. All [Fe,Al]MFI catalysts contain ca. 90% of iron in the high-spin Fe²⁺ state, independent of the iron concentration (0.075–0.6 wt.% iron). In the presence of N₂O at 623 K, most Fe²⁺ ions (>90%) were oxidized to Fe³⁺ ions as deduced from Mössbauer spectroscopy. In the presence of benzene, subsequent reduction of Fe³⁺ to Fe²⁺ takes place. However, not all of the oxidized Fe²⁺ to Fe³⁺ ions were able to selectively oxidize benzene to phenol. This indicates that only a fraction of iron is catalytically active. For [Fe,Al]MFI catalysts with relatively high iron concentration, most of the extra-framework iron species formed are inactive in the direct oxidation of benzene to phenol. Finally, a more detailed in situ Mössbauer study for one sample, i.e. [Fe,Al]MFI (1:8) catalyst, was performed to illustrate the reduction/oxidation properties of the different iron species formed after steam-treatment.     

Stimulus Responsive Poly(ferrocenylsilanes): Redox Chemistry of Iron in the Main Chain

Redox chemistry of organometallic poly(ferrocenylsilane) polymers (soluble in organic or aqueous environment) is discussed. Poly(ferrocenyldimethylsilane) (PFDMS) was oxidized in CH₂Cl₂ solution with different oxidants. Oxidation was accomplished with stepwise increasing amounts of ferric chloride (FeCl₃), iodine (I₂) and tris(4-bromophenyl)ammoniumyl hexachloroantimonate ( ). The process was followed by UV–visible spectroscopy. Mixed-valence salts with different Fe(III)/Fe(II) ratios were obtained. The oxidation products were characterized by Mössbauer spectroscopy, which proved to be a very valuable tool to analyze mixed valence ferrocenyl compounds. Mössbauer analysis demonstrated that 100% oxidation could be achieved with TBPA^{· +}. Decamethylferrocene (DMFC) was found to be a suitable reducing agent for the oxidized polymer. The reduction process was monitored by UV–visible spectroscopy. The polymer was characterized by gel permeation chromatography (GPC) following the oxidation/reduction cycle and evidence of some fragmentation of the chains was observed. A water-soluble PFS polycation was successfully oxidized with FeCl₃ for pH values between 4 and 5. Ascorbic acid (vitamin C) was found to completely reduce the oxidized water-soluble polymer.     

Synthesis, characterization, and unique catalytic performance of the mesoporous material Fe-TUD-1 in Friedel–Crafts benzylation of benzene

Iron (Fe)-containing mesoporous TUD-1 catalysts (denoted as Fe-TUD-1) with different Si/Fe ratios (100, 50, 20 and 10) were synthesized using triethanolamine as a template. They were characterized by XRD, elemental analysis, N₂ ad/desorption measurements, HR-TEM, UV–vis, ²⁹Si NMR, and ⁵⁷Fe Mössbauer spectroscopies. Catalytic performance was tested in the Friedel–Crafts benzylation of benzene. Fe-TUD-1 showed excellent activity, with 100% conversion and 100% selectivity towards diphenylmethane, superior to other metal-containing TUD-1 (e.g. Ga, Sn, and Ti) or other Fe-containing mesoporous materials (e.g. Fe-MCM-41 and Fe-HMS).     

Ramping down a clinical 3 T scanner: a journey into MRI and MRS at 0.75 T

Object

Lower-field MR is reemerging as a viable, potentially cost-effective alternative to high-field MR, thanks to advances in hardware, sequence design, and reconstruction over the past decades. Evaluation of lower field strengths, however, is limited by the availability of lower-field systems on the market and their considerable procurement costs. In this work, we demonstrate a low-cost, temporary alternative to purchasing a dedicated lower-field MR system.

Materials and Methods

By ramping down an existing clinical 3 T MRI system to 0.75 T, proton signals can be acquired using repurposed ¹³C transmit/receive hardware and the multi-nuclei spectrometer interface. We describe the ramp-down procedure and necessary software and hardware changes to the system.

Results

Apart from presenting system characterization results, we show in vivo examples of cardiac cine imaging, abdominal two- and three-point Dixon-type water/fat separation, water/fat-separated MR Fingerprinting, and point-resolved spectroscopy. In addition, the ramp-down approach allows unique comparisons of, e.g., gradient fidelity of the same MR system operated at different field strengths using the same receive chain, gradient coils, and amplifiers.

Discussion

Ramping down an existing MR system may be seen as a viable alternative for lower-field MR research in groups that already own multi-nuclei hardware and can also serve as a testing platform for custom-made multi-nuclei transmit/receive coils.