The apolipoprotein E epsilon 4 allele does not influence the clinical expression of the amyloid precursor protein gene codon 693 or 692 mutations

In 31 symptomatic and 5 asymptomatic carriers of the amyloid precursor protein (APP) gene codon 693 mutation, 10 family members without mutation, and 5 carriers of the APP gene codon 692 mutation (3 with early-onset Alzheimer dementia, 2 with cerebral hemorrhage), a high frequency of the apolipoprotein E epsilon 4 allele was found. Age at onset, age at death, occurrence of dementia, and number of strokes did not differ between APP gene mutation carriers with or without epsilon 4 allele, showing that the clinical expression of these APP mutations is not influenced by the apolipoprotein E gene.     

Computer signal processing of long duration biotelemetric brain data

The EEG represents brain processing under diverse physiological conditions. A complete system involving acquisition and quantitation of this important information about brain function is described. The time-domain EEG and other biological signals are obtained using a multichannel PAM/FM biotelemeter mounted on the head of the experimental animal. This data is transmitted, demodulated and recorded by electronic recording techniques. A computer-based EEG analysis system is described for acquiring the primary data and transforming it into the frequency domain using Fourier methods. The computing system is developed to semi-automatically signal process about 4 h of eight channel EEG records. Data compression by plotting in a quasi-three-dimensional spectral profile allows visual correlations of pattern features to drug manipulations, etc. The software programs are briefly described for each step in signal processing. The feasibility of the complete system approach is demonstrated using biotelemetry to acquire low voltage EEG signals without behavioral distortions or introduction of artifacts by cables.     

Glass Transition, Water, and Glycerol Effects on Sucrose Inversion in Pullulan-Sucrose Systems

ABSTRACT: Glass transition, water, and glycerol effects on sucrose inversion were investigated in pullulan-sucrose systems. Pullulan-sucrose (2:1), PS was dissolved into distilled water. Pullulan-sucrose-invertase, PSI, and pullulan-sucrose-invertase-glycerol, PSIG, were prepared by adding tiny amounts of invertase and glycerol, respectively, to similar PS blends. Samples were freeze-dried, further dehydrated over P₂O₅, and their physical properties were determined using water sorption isotherms and DSC. The amount of glucose formed by sucrose hydrolysis in samples stored at various RH was monitored. Water and glycerol plasticized the systems. DSC thermograms indicated complex phase behavior in PSI and PSIG depending on water content. Glycerol increased sucrose hydrolysis at 0.538 a_w, and favours it even at very moderate a_w.     

Reflector materials for two‐dimensional low‐concentrating photovoltaic systems: the effect of specular versus diffuse reflectance on the module efficiency

Photovoltaic modules in two‐dimensional low‐concentrating systems with specular parabolic reflectors often experience high local irradiance that causes high local currents and cell temperatures. This generally results in power losses. The use of low‐angle scattering reflectors gives a smoother irradiance distribution, which results in a higher fill factor. In order to study how the choice of reflector material influences system performance, two different reflector materials (anodised aluminium and lacquered rolled aluminium laminated on a plastic substrate) were compared. The total and diffuse reflectance spectra of the reflector materials were measured, the integrated hemispherical and specular solar reflectance values calculated, and the angular distributions of scattered light investigated. Two geometrically identical 3× concentrating photovoltaic systems with semi‐parabolic over edge reflectors of the different materials were tested outdoors. While the anodised aluminium reflector, which had higher hemispherical and specular solar reflectance, resulted in a higher short‐circuit current, the low‐angle scattering lacquered foil gave a higher fill factor, due to a smoother image of the sun on the module surface, and an equally high calculated annual electricity production. Given its low price, the latter reflector should thus be more cost‐effective in low‐concentrating photovoltaic systems. Copyright © 2005 John Wiley & Sons, Ltd.     

Spectrally selective and adaptive surfaces for protection against radiative heating: ITO and VO2

Two surface materials for reducing absorptivity of heat radiation from fires have been investigated. The first is VO₂, which is a thermochromic material. When the temperature of a VO₂ surface increases over a certain temperature, it switches, ideally, from infrared (IR)‐absorbing to IR‐reflecting. VO₂ window coatings are still on a research level, yet to be commercialized. In this study, VO₂ powder available on the market was investigated. The thermochromic effect could be identified but was not large enough to significantly improve the fire properties of treated surfaces. Some thoughts concerning how to improve the performance of VO₂ are discussed. The second investigated material is indium tin oxide (ITO), which is a so called low‐e coating, which means that it has low emissivity and absorptivity in the IR part of the spectrum. ITO is spectrally selective in the sense that it transmits visible light while reflecting a large fraction of the IR radiation, which is a rare property for surfaces in general but a typical property of thin electrically conducting non‐metallic films. It is shown that the application of ITO to poly(methyl methacrylate) (PMMA) significantly improves its fire properties. ITO coating is a mature technology already in widespread use today in the electronics industry. Copyright © 2012 John Wiley & Sons, Ltd.     

Scanning mass spectrometer for quantitative reaction studies on catalytically active microstructures

We describe an apparatus for spatially resolving scanning mass spectrometry which is able to measure the gas composition above catalytically active microstructures or arrays of these microstructures with a lateral resolution of better than 100 mum under reaction conditions and which allows us to quantitatively determine reaction rates on individual microstructures. Measurements of the three-dimensional gas composition at different vertical distances and separations between active structures allow the evaluation of gas phase mass transport effects. The system is based on a piezoelectrically driven positioning substage for controlled lateral and vertical positioning of the sample under a rigidly mounted capillary probe connecting to a mass spectrometer. Measurements can be performed at pressures in the range of <10(-2)-10 mbars and temperatures between room temperature and 450 degrees C. The performance of the setup is demonstrated using the CO oxidation reaction on Pt microstructures on Si with sizes between 100 and 300 mum and distances in the same order of magnitude, evaluating CO(2) formation and CO consumption above the microstructures. The rapidly decaying lateral resolution with increasing distance between sample and probe underlines the effects of (lateral) gas transport in the room between sample and probe. The reaction rates and apparent activation energy obtained from such measurements agree with previous data on extended surfaces, demonstrating the feasibility of determining absolute reaction rates on individual microstructures.     

The Effect of Supersaturation on the Internal Oxidation of Binary Alloys

According to the theory of Bohm and Kahlweit ofthe internal oxidation of binary A-B alloys, theparabolic rate constant for the formation of reasonablystable internal BO oxides as well as theconcentrations of O and B at the oxidation front arecontrolled only by the degree of supersaturationnecessary for the nucleation of new oxide particles. Theeffects of this factor on the previous parameters arecalculated for various values of the solubility product ofthe oxide and of the diffusion coefficients of O and B.Moreover, an alternative procedure for the calculationof the critical degree of supersaturation behind the precipitation front required for oxideprecipitation, which is a function of the concentrationof the reactants at the internal oxidation front, isproposed. A simple modification of Wagner's theory of internal oxidation is also presented, andits results are compared with those of the treatment byBohm and Kahlweit. Finally, the limitations of the twomethods are examined.     

Tribological behaviour and internal stress of diamond coating deposited with a stationary d.c. plasma jet

A diamond coating was produced by a stationary d.c. plasma jet in a confined circular area. Using scanning electron microscopy, optical microscopy, laser profilometry and Raman spectroscopy, it was found that the diamond coated area is inhomogeneous with respect to morphology, purity, thickness, and internal stress. Surrounding the diamond coated central area, an amorphous carbon rich area was identified. The morphologically distinct regions were evaluated separately in a fretting wear test against a corundum counterbody. The frictional behaviour was observed to be dependent on the morphology and structure of the coating and the diamond crystal size and orientation in the diamond coated area. No evidence of any fretting wear damage was found in the diamond coated area, whereas a lot of fretting induced scratches were observed in the amorphous carbon rich area. The presence of wear debris was clearly observed in the fretting contacts both inside and outside the diamond coated area.