We have purified and characterized the cerebral amyloid protein that forms the plaque core in Alzheimer disease and in aged individuals with Down syndrome. The protein consists of multimeric aggregates of a polypeptide of about 40 residues (4 kDa). The amino acid composition, molecular mass, and NH2-terminal sequence of this amyloid protein are almost identical to those described for the amyloid deposited in the congophilic angiopathy of Alzheimer disease and Down syndrome, but the plaque core proteins have ragged NH2 termini. The shared 4-kDa subunit indicates a common origin for the amyloids of the plaque core and of the congophilic angiopathy. There are superficial resemblances between the solubility characteristics of the plaque core and some of the properties of scrapie infectivity, but there are no similarities in amino acid sequences between the plaque core and scrapie polypeptides.There are several closely associated morphologic changes in the brains of individuals with Alzheimer disease (AD): neurofibrillary tangles (NFTs) within neurons; plaques consisting of various proportions of amyloid cores (APCs) § surrounded by neuritic degeneration; a variable degree of congophilic angiopathy (ACA); and widespread neuronal loss and gliosis in areas affected by NFTs and plaque formation. The composition of the NFT is still in doubt due in part to the difficulty in achieving complete solubilization (2).Little is known about the pathogenesis of the APC, particularly whether the amyloid core precedes or proceeds from the surrounding neuritic degeneration. Since the amyloid plaque also occurs in some of the unconventional virus infections (3), and because recent data have drawn attention to the similarities between amyloid fibrils and the infectious agent of scrapie (4), speculation has naturally increased over the possible infectious nature of amyloid in AD. As a direct approach to unraveling the pathogenesis of the AD plaque, we have isolated and purified the amyloid from the cores of the plaques. For comparison, we have also studied the APC from the brains of an aged individual with Down syndrome (DS), in which the typical changes of AD also occur. MATERIALS AND METHODSSelection of Samples. For AD and DS cases, at the time of autopsy, one half of the brain was frozen at -70°C and the remaining half was fixed in Formalin for subsequent histological confirmation. Control brain samples were taken from individuals in whom there was no histological evidence of APC or NFT.Isolation and Purification of APCs. The frozen hemisphere is partially thawed and sliced at 1-cm intervals. The cortical grey matter is collected for homogenization (Sorvall Omnimixer) in buffer 1 (10 mM Tris HCl/150 mM NaCl/5 mM EDTA/1% Triton-X 100/0.4 mM phenylmethylsulfonyl fluoride, pH 7.2) at a sample-to-buffer ratio of 1:9 (wt/vol). This homogenate is stirred on ice for 10 min, then centrifuged at 10,000 x g for 20 min (Sorvall RC2-B, GSA rotor, 40C). The supernatant is discarded and the pellet is extracted with stirring for 20 min on i...

Successful identification of complex odors by sensor arrays remains a challenging problem. Herein, we report robust, category-specific multiclass-time series classification using an array of 20 carbon nanotube-based chemical sensors. We differentiate between samples of cheese, liquor, and edible oil based on their odor. In a two-stage machinelearning approach, we first obtain an optimal subset of sensors specific to each category and then validate this subset using an independent and expanded data set. We determined the optimal selectors via independent selector classification accuracy, as well as a combinatorial scan of all 4845 possible four selector combinations. We performed sample classification using two modelsa k-nearest neighbors model and a random forest model trained on extracted features. This protocol led to high classification accuracy in the independent test sets for five cheese and five liquor samples (accuracies of 91% and 78%, respectively) and only a slightly lower (73%) accuracy on a five edible oil data set.

The fabrication of a planar guard ring diode which exhibits uniform microplasma-free breakdown is described. Discrepancies are discussed between the behavior of these junctions and those reported by Batdorf et al. and Chynoweth, including results showing extremely hard V-I characteristics associated with uniform avalanche breakdown. Experimental evidence is presented which confirms Shockley's theory in which the breakdown behavior is predicted from the Poisson distribution of impurities within the space-charge layer. The photomultiplication technique as described in Paper I is applied to uniform p—n junctions. The linearity of 1/M vs V, as predicted by theory, was verified for values of M between 1.6 and 500. For higher values, the multiplication curves deviate from a straight line. In this higher range they are in good agreement with the pulse-multiplication model developed in Paper I. Light emission patterns from these junctions are shown and a correlation between these patterns and crystal properties is discussed. The effects of resistivity striations in the silicon single crystals is shown to have a strong effect on breakdown areas and no effects of dislocations and oxygen on uniformity are found. From capacity and multiplication measurements a value for the breakdown field of EB=445±25 kV/cm was obtained for a 32-V junction.

Stimuli-responsive materials offer new opportunities to resolve long-standing materials challenges and are rapidly gaining pivotal roles in diverse applications. For example, smart protective garments This article is protected by copyright. All rights reserved. 2 that rapidly transport water vapor and autonomously block chemical threats are expected to enable an effective new paradigm of adaptive personal protection. However, the incorporation of these seemingly incompatible properties into a single responsive system remains elusive. Herein, we demonstrate a bistable membrane that can rapidly, selectively, and reversibly transition from a highly breathable state in a safe environment to a chemically protective state when exposed to organophosphate threats such as sarin. Dynamic response to chemical stimuli is achieved through the physical collapse of an ultrathin copolymer layer on the membrane surface, which efficiently gates transport through membrane pores composed of single-walled carbon nanotubes (SWNT). The adoption of nanometer-wide SWNTs for ultrafast moisture conduction enables a simultaneous boost in size-sieving selectivity and water-vapor permeability by decreasing nanotube diameter, thereby overcoming the breathability/protection trade-off that limits conventional membrane materials.Adaptive multifunctional membranes based on this platform greatly extend the active use of a protective garment and present exciting opportunities in many other areas including separation processes, sensing, and smart delivery.