Three-Dimensional Morphology of a Coronal Prominence Cavity

We present a three-dimensional density model of coronal prominence cavities, and a morphological fit that has been tightly constrained by a uniquely well-observed cavity. Observations were obtained as part of an International Heliophysical Year campaign by instruments from a variety of space- and ground-based observatories, spanning wavelengths from radio to soft-X-ray to integrated white light. From these data it is clear that the prominence cavity is the limb manifestation of a longitudinally-extended polar-crown filament channel, and that the cavity is a region of low density relative to the surrounding corona. As a first step towards quantifying density and temperature from campaign spectroscopic data, we establish the three-dimensional morphology of the cavity. This is critical for taking line-of-sight projection effects into account, since cavities are not localized in the plane of the sky and the corona is optically thin. We have augmented a global coronal streamer model to include a tunnel-like cavity with elliptical cross-section and a Gaussian variation of height along the tunnel length. We have developed a semi-automated routine that fits ellipses to cross-sections of the cavity as it rotates past the solar limb, and have applied it to Extreme Ultraviolet Imager (EUVI) observations from the two Solar Terrestrial Relations Observatory (STEREO) spacecraft. This defines the morphological parameters of our model, from which we reproduce forward-modeled cavity observables. We find that cavity morphology and orientation, in combination with the viewpoints of the observing spacecraft, explains the observed variation in cavity visibility for the east vs. west limb

Reactivity of Metal-Free and Metal-Associated Amyloid-?? with Glycosylated Polyphenols and Their Esterified Derivatives

Both amyloid-?? (A??) and transition metal ions are shown to be involved in the pathogenesis of Alzheimer???s disease (AD), though the importance of their interactions remains unclear. Multifunctional molecules, which can target metal-free and metal-bound A?? and modulate their reactivity (e.g., A?? aggregation), have been developed as chemical tools to investigate their function in AD pathology; however, these compounds generally lack specificity or have undesirable chemical and biological properties, reducing their functionality. We have evaluated whether multiple polyphenolic glycosides and their esterified derivatives can serve as specific, multifunctional probes to better understand AD. The ability of these compounds to interact with metal ions and metal-free/-associated A??, and further control both metal-free and metal-induced A?? aggregation was investigated through gel electrophoresis with Western blotting, transmission electron microscopy, UV-Vis spectroscopy, fluorescence spectroscopy, and NMR spectroscopy. We also examined the cytotoxicity of the compounds and their ability to mitigate the toxicity induced by both metal-free and metal-bound A??. Of the polyphenols investigated, the natural product (Verbascoside) and its esterified derivative (VPP) regulate the aggregation and cytotoxicity of metal-free and/or metal-associated A?? to different extents. Our studies indicate Verbascoside represents a promising structure for further multifunctional tool development against both metal-free A?? and metal-A??.open0

Self-assembly and anti-amyloid cytotoxicity activity of amyloid beta peptide derivatives

The self-assembly of two derivatives of KLVFF, a fragment Abeta(16-20) of the amyloid beta (Abeta) peptide, is investigated and recovery of viability of neuroblastoma cells exposed to Abeta is observed at sub-stoichiometric peptide concentrations. Fluorescence assays show that NH2-KLVFF-CONH2 undergoes hydrophobic collapse and amyloid formation at the same critical aggregation concentration (cac). In contrast, NH2-K(Boc)LVFF-CONH2 undergoes hydrophobic collapse at a low concentration, followed by amyloid formation at a higher cac. These findings are supported by the beta-sheet features observed by FTIR. Electrospray ionization mass spectrometry indicates that NH2-K(Boc)LVFF-CONH2 forms a significant population of oligomeric species above the cac. Cryo-TEM, used together with SAXS to determine fibril dimensions, shows that the length and degree of twisting of peptide fibrils seem to be influenced by the net peptide charge. Grazing incidence X-ray scattering from thin peptide films shows features of beta-sheet ordering for both peptides, along with evidence for lamellar ordering of NH2-KLVFF-CONH2. This work provides a comprehensive picture of the aggregation properties of these two KLVFF derivatives and show their utility, in unaggregated form, in restoring the viability of neuroblastoma cells against Abeta-induced toxicity

Association of Mild Anemia with Cognitive, Functional, Mood and Quality of Life Outcomes in the Elderly: The “Health and Anemia” Study

BACKGROUND: In the elderly persons, hemoglobin concentrations slightly below the lower limit of normal are common, but scant evidence is available on their relationship with significant health indicators. The objective of the present study was to cross-sectionally investigate the association of mild grade anemia with cognitive, functional, mood, and quality of life (QoL) variables in community-dwelling elderly persons. METHODS: Among the 4,068 eligible individuals aged 65-84 years, all persons with mild anemia (n = 170) and a randomly selected sample of non-anemic controls (n = 547) were included in the study. Anemia was defined according to World Health Organization (WHO) criteria and mild grade anemia was defined as a hemoglobin concentration between 10.0 and 11.9 g/dL in women and between 10.0 and 12.9 g/dL in men. Cognition and functional status were assessed using measures of selective attention, episodic memory, cognitive flexibility and instrumental and basic activities of daily living. Mood and QoL were evaluated by means of the Geriatric Depression Scale-10, the Short-Form health survey (SF-12), and the Functional Assessment of Cancer Therapy-Anemia. RESULTS: In univariate analyses, mild anemic elderly persons had significantly worse results on almost all cognitive, functional, mood, and QoL measures. In multivariable logistic regressions, after adjustment for a large number of demographic and clinical confounders, mild anemia remained significantly associated with measures of selective attention and disease-specific QoL (all fully adjusted p<.046). When the lower limit of normal hemoglobin concentration according to WHO criteria was raised to define anemia (+0.2 g/dL), differences between mild anemic and non anemic elderly persons tended to increase on almost every variable. CONCLUSIONS: Cross-sectionally, mild grade anemia was independently associated with worse selective attention performance and disease-specific QoL ratings

Arcjet power conditioning unit ::design characteristics and preliminary tests

In this paper a low power (1.8 kW), high frequency (33 kHz), no-flight breadboard of Power Conditioning Unit (PCU) for arcjet application is described. The structure and the main electrical data of the PCU are presented, with particular car to the two fundamental hardware blocks: the start-up unit and the DC/DC converter for the arc supply. The PCU control is described too. Also the control description can be divided in two main blocks: the analog and the digital section. Finally, the start-up control technique is described. After the review of the technical characteristics of the PCU, preliminary test results on arcjet simulator are presented

The ongoing search for small molecules to study metal-Associated amyloid-?? species in alzheimers disease

ConspectusThe development of a cure for Alzheimers disease (AD) has been impeded by an inability to pinpoint the root cause of this disorder. Although numerous potential pathological factors have been indicated, acting either individually or mutually, the molecular mechanisms leading to disease onset and progression have not been clear. Amyloid-?? (A??), generated from proteolytic processing of the amyloid precursor protein (APP), and its aggregated forms, particularly oligomers, are suggested as key pathological features in AD-Affected brains. Historically, highly concentrated metals are found colocalized within A?? plaques. Metal binding to A?? (metal-A??) generates/stabilizes potentially toxic A?? oligomers, and produces reactive oxygen species (ROS) in vitro (redox active metal ions; plausible contribution to oxidative stress). Consequently, clarification of the relationship between A??, metal ions, and toxicity, including oxidative stress via metal-A??, can lead to a deeper understanding of AD development.To probe the involvement of metal-A?? in AD pathogenesis, rationally designed and naturally occurring molecules have been examined as chemical tools to target metal-A?? species, modulate the interaction between the metal and A??, and subsequently redirect their aggregation into nontoxic, off-pathway unstructured aggregates. These ligands are also capable of attenuating the generation of redox active metal-A??-induced ROS to mitigate oxidative stress. One rational design concept, the incorporation approach, installs a metal binding site into a framework known to interact with A??. This approach affords compounds with the simultaneous ability to chelate metal ions and interact with A??. Natural products capable of A?? interaction have been investigated for their influence on metal-induced A?? aggregation and have inspired the construction of synthetic analogues. Systematic studies of these synthetic or natural molecules could uncover relationships between chemical structures, metal/A??/metal-A?? interactions, and inhibition of A??/metal-A?? reactivity (i.e., aggregation modes of A??/metal-A??; associated ROS production), suggesting mechanisms to refine the design strategy.Interdisciplinary investigations have demonstrated that the designed molecules and natural products control the aggregation pathways of metal-A?? species transforming their size/conformation distribution. The aptitude of these molecules to impact metal-A?? aggregation pathways, either via inhibition of A?? aggregate formation, most importantly of oligomers, or disaggregation of preformed fibrils, could originate from their formation of complexes with metal-A??. Potentially, these molecules could direct metal-A?? size/conformational states into alternative nontoxic unstructured oligomers, and control the geometry at the A??-ligated metal center for limited ROS formation to lessen the overall toxicity induced by metal-A??. Complexation between small molecules and A??/metal-A?? has been observed by nuclear magnetic resonance spectroscopy (NMR) and ion mobility-mass spectrometry (IM-MS) pointing to molecular level interactions, validating the design strategy. In addition, these molecules exhibit other attractive properties, such as antioxidant capacity, prevention of ROS production, potential blood-brain barrier (BBB) permeability, and reduction of A??-/metal-A??-induced cytotoxicity, making them desirable tools for unraveling AD complexity. In this Account, we summarize the recent development of small molecules, via both rational design and the selection and modification of natural products, as tools for investigating metal-A?? complexes, to advance our understanding of their relation to AD pathology.close5

Shipboard Control System Supported by Energy Storage Sizing to Meet the MIL-STD-1399 Limits for Pulsed Power Loads

This article addresses the new pulsed power load requirements for shipboard power systems introduced in the 2018 revision of the Military Standard 1399 Section 300, Part 1. With the number of pulsed loads increasing onboard modern ships, the ac distribution bus is susceptible to voltage and frequency abnormalities due to the limited inertia of the synchronous generators powering the ship. In this article, the strict limits imposed by the Military Standard 1399 are met with a system-level solution and a novel sizing method for the energy storage system (ESS). A targeted control system ensures that the power delivered by the ac bus has smooth transients, within the limits set by the military standard, thus reducing the stress on the shipboard power distribution system and the generators. A novel ESS sizing algorithm is proposed to identify the minimum number of supercapacitors for a given set of control parameters. The proposed control system is simulated and experimentally validated on a laboratory testbed built with silicon carbide (SiC) power converters managed by field programmable gate array (FPGA) control board

Photophysical properties of the new phosphorescent platinum(II) and palladium(II) complexes of benzoporphyrins and chlorins

Several phosphorescent platinum(II) and palladium(II) complexes of tetrapyrrole dyes are prepared in an attempt to improve the compatibility with red laser diodes. The nature of meso-substituents in benzoporphyrin macrocycle is found to affect mainly the position of the Soret band and has little influence on the Q-bands. In rigid polymeric matrices these dyes possess more favourable photochemical properties than corresponding meso-tetraphenyltetrabenzoporphyrins. Platinum(II) chlorins show good compatibility with 635 nm laser diode and 632.8 line of He-Ne laser, and have moderate brightness with emission yields ∼2%. Photophysical properties and photostability of these dyes is assessed and compared with the known NIR-emitting oxygen indicators. © 2009 Elsevier B.V. All rights reserved