A Comparative Study of Infrared Asteroid Surveys: IRAS, AKARI, and WISE

We present a comparative study of three infrared asteroid surveys based on the size and albedo data from the Infrared Astronomical Satellite (IRAS), the Japanese infrared satellite AKARI, and the Wide-field Infrared Survey Explorer (WISE). Our study showed that: (i) the total number of asteroids detected with diameter and albedo information with these three surveyors is 138,285, which is largely contributed by WISE; (ii) the diameters and albedos measured by the three surveyors for 1,993 commonly detected asteroids are in good agreement, and within +/-10% in diameter and +/-22% in albedo at 1sigma deviation level. It is true that WISE offers size and albedo of a large fraction (>20%) of known asteroids down to a few km bodies, but we would suggest that the IRAS and AKARI catalogs compensate for larger asteroids up to several hundred km, especially in the main belt region. We discuss the complementarity of these three catalogs in order to facilitate the use of these data sets for characterizing the physical properties of minor planets.Comment: 21 pages, 19 figures, and 2 tables, accepted for publication in PAS

Characterization of Adsorbed Molecular Water on the Surface of a Stretched Polytetrafluoroethylene Tape Analyzed by1H NMR

A single molecule often exhibits a largely different material character from a bulk matter. Although a perfluoroalkyl (Rf) compound is a representative one, many interests have mostly been devoted to the bulk character only thus far, leaving the single molecular character unclear. Recently, a new theoretical framework, stratified dipole-arrays (SDA) theory, has appeared for comprehensive understanding of Rf compounds in terms of both single and bulk systems. On this theory, a mechanically stretched polytetrafluoroethylene (PTFE) is expected to exhibit a single-molecular character having dipole-driven properties, which should attract molecular water. In the present study, a stretched PTFE tape is revealed to attract molecular water (not water droplet) in fact, and the adsorbed water molecules are highly restricted in motion by the dipole–dipole interaction studied by using 1H NMR, which agrees with the prediction by the SDA theory

Stereoisomer-dependent conversion of dinaphthothienothiophene precursor films

Soluble precursor materials of organic semiconductors are employed for fabricating solution-processable thin film devices. While the so-called precursor approach has already been tried for various organic electronic devices such as transistors and solar cells, understanding of the conversion process in the film lags far behind. Here, we report that molecular aggregation of the precursor compound significantly influences the thermal conversion reaction in the film. For this study, two stereoisomers of a dinaphthothienothiophene (DNTT) precursor that are the endo- and exo-DNTT-phenylmaleimide monoadducts are focused on. The structural change during the thermal conversion process has been investigated by a combination of infrared spectroscopy and X-ray diffraction techniques. The results show that the endo-isomer is readily converted to DNTT in the film by heating, whereas the exo-isomer exhibits no reaction at all. This reaction suppression is found to be due to the self-aggregation property of the exo-isomer accompanying the intermolecular C–H⋯O interactions. This finding shows a new direction of controlling the on-surface reaction, as well as the importance of analyzing the film structure at the initial stage of the reaction

Aβ accumulation causes MVB enlargement and is modelled by dominant negative VPS4A.

BACKGROUND: Alzheimer's disease (AD)-linked β-amyloid (Aβ) accumulates in multivesicular bodies (MVBs) with the onset of AD pathogenesis. Alterations in endosomes are among the earliest changes associated with AD but the mechanism(s) that cause endosome enlargement and the effects of MVB dysfunction on Aβ accumulation and tau pathology are incompletely understood. METHODS: MVB size and Aβ fibrils in primary neurons were visualized by electron microscopy and confocal fluorescent microscopy. MVB-dysfunction, modelled by expression of dominant negative VPS4A (dnVPS4A), was analysed by biochemical methods and exosome isolation. RESULTS: Here we show that AD transgenic neurons have enlarged MVBs compared to wild type neurons. Uptake of exogenous Aβ also leads to enlarged MVBs in wild type neurons and generates fibril-like structures in endocytic vesicles. With time fibrillar oligomers/fibrils can extend out of the endocytic vesicles and are eventually detectable extracellularly. Further, endosomal sorting complexes required for transport (ESCRT) components were found associated with amyloid plaques in AD transgenic mice. The phenotypes previously reported in AD transgenic neurons, with net increased intracellular levels and reduced secretion of Aβ, were mimicked by blocking recycling of ESCRT-III by dnVPS4A. DnVPS4A further resembled AD pathology by increasing tau phosphorylation at serine 396 and increasing markers of autophagy. CONCLUSIONS: We demonstrate that Aβ leads to MVB enlargement and that amyloid fibres can form within the endocytic pathway of neurons. These results are consistent with the scenario of the endosome-lysosome system representing the site of initiation of Aβ aggregation. In turn, a dominant negative form of the CHMP2B-interacting protein VPS4A, which alters MVBs, leads to accumulation and aggregation of Aβ as well as tau phosphorylation, mimicking the cellular changes in AD

Accurate Molecular Orientation Analysis Using Infrared pMAIRS Considering the Refractive Index of the Thin Film Sample

Infrared (IR) p-polarized multiple-angle incidence resolution spectrometry (pMAIRS) is a powerful tool for analyzing the molecular orientation in an organic thin film. In particular, pMAIRS works powerfully for a thin film with a highly rough surface irrespective of degree of the crystallinity. Recently, the optimal experimental condition has comprehensively been revealed, with which the accuracy of the analytical results has largely been improved. Regardless, some unresolved matters still remain. A structurally isotropic sample, for example, yields different peak intensities in the in-plane and out-of-plane spectra. In the present study, this effect is shown to be due to the refractive index of the sample film and a correction factor has been developed using rigorous theoretical methods. As a result, with the use of the correction factor, organic materials having atypical refractive indices such as perfluoroalkyl compounds (n = 1.35) and fullerene (n = 1.83) can be analyzed with high accuracy comparable to a compound having a normal refractive index of approximately 1.55. With this improved technique, we are also ready for discriminating an isotropic structure from an oriented sample having the magic angle of 54.7°

Mechanisms of Neuronal Death in Synucleinopathy

α-synuclein is a key molecule in the pathogenesis of synucleinopathy including Parkinson's disease and multiple system atrophy. In this mini-review, we mainly focus on recent data obtained from cellular models of synucleinopathy and discuss the possible mechanisms of neurodegeneration. Recent progress suggests that the aggregate formation of α-synuclein is cytoprotective and that its precursor oligomer (protofibril) may be cytotoxic. The catechol-derived quinones are the candidate molecules that facilitate the oligomer formation of α-synuclein. Furthermore, the cellular membranes are shown to be the primary targets injured by mutant α-synucleins, and the mitochondrial dysfunction seems to be an initial step in the neuronal death

Tyrosinase-Expressing Neuronal Cell Line as in Vitro Model of Parkinson’s Disease

Oxidized metabolites of dopamine known as dopamine quinone derivatives are thought to play a pivotal role in the degeneration of nigrostriatal dopaminergic neurons in Parkinson’s disease. Although such quinone derivatives are usually produced via the autoxidation of catecholamines, tyrosinase, which is a key enzyme in melanin biosynthesis via the production of DOPA and subsequent molecules, can potentially accelerate the induction of catecholamine quinone derivatives by its oxidase activity. We have developed neuronal cell lines in which the expression of human tyrosinase was inducible. Overexpression of tyrosinase resulted in increased intracellular dopamine content in association with the formation of melanin pigments in neuronal somata, which eventually causes apoptotic cell death. This cellular model will provide a useful tool for detailed analyses of the neurotoxicity of oxidized catechol metabolites

Non-uniform distribution of the contraction/extension (C–E) in the left ventricular myocardium related to the myocardial function

AbstractObjectiveWe attempted to disclose the microscopic characteristics of the non-uniform distribution of the contraction and extension (C–E) of the left ventricular (LV) myocardium using a new methodology (echo-dynamography).MethodsThe distributions of the “axial strain rate” (aSR) and the intra-mural velocity in the local areas of the free wall including the posterior wall (PW) and interventricular septum (IVS) were microscopically obtained using echo-dynamography with a high accuracy of 821μm in the spatial resolution. The results were shown by the color M-mode echocardiogram or curvilinear graph. Subjects were 10 presumably normal volunteers.Results(1)Both the C–E in the pulsating LV wall showed non-uniformity spatially and time-sequentially.(2)The C–E property was better evaluated by the aSR distribution method rather than the intra-mural velocity distribution method.(3)Two types of non-uniformity of the aSR distribution were observed: i.e. (i) the difference of its (+)SR (contraction: C) or (−)SR (extension: E) was solely the “magnitude”; (ii) the coexistence of both the (+) SR and (−)SR at the same time.(4)The aSR distribution during systole was either “spotted,” or “multi-layered,” or “toned” distribution, whereas “stratified,” “toned,” or “alternating” distributions were observed during diastole.(5)The aSR distribution in the longitudinal section plane was varied in the individual areas of the wall even during the same timing.(6)To the mechanical function of the LV, there was a different behavior between the IVS and PW.ConclusionsThe aSR and its distribution were the major determinants of the C–E property of the LV myocardium. Spatial as well as time-sequential uniformity of either contraction or extension did not exist. The myocardial function changed depending on the assemblage of the aSR distribution, and by the synergistic effect of (+)SR and (−)SR, the non-uniformity itself potentially served to hold the smooth LV mechanical function