209 research outputs found

    The Other SiO2: Investigating Oxidation of Alcohols Using (NH4)2Cr2O7 in Sand

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    Oxidation of alcohols to aldehydes and ketones is one of the classical reactions in organic chemistry which is utilized frequently in medicine, industry, and pharmaceuticals. Classical effective reagents in oxidation include pyridinium chlorochromate, potassium permanganate, Jones reagent, bleach, and Swern conditions. There has been an increasing interest throughout the years to use supported-based reagents in tandem with these reagents, particularly with silica gel especially towards Cr-based oxidizing agents. Despite the abundance of reported reactions in the literature pertaining to silica gel, little is known about sand, despite both are silicon dioxide and exhibit similar porosity and crystallinity. It is not clear as why silica gel is frequently used in chemical reactions compared to sand. Herein, we report some of our results regarding the utilization of washed sand in oxidation of primary and secondary alcohols. Using an appropriate solvent under reflux, primary and secondary alcohols are oxidized cleanly into aldehydes and ketones based on TLC monitoring and 1H and 13C-NMR of the crude material. More importantly, reactions can be carried out in lower reagent loading compared to silica-gel based oxidations

    Relevance of Spectral Cues for Auditory Spatial Processing in the Occipital Cortex of the Blind

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    We have previously shown that some blind individuals can localize sounds more accurately than their sighted counterparts when one ear is obstructed, and that this ability is strongly associated with occipital cortex activity. Given that spectral cues are important for monaurally localizing sounds when one ear is obstructed, and that blind individuals are more sensitive to small spectral differences, we hypothesized that enhanced use of spectral cues via occipital cortex mechanisms could explain the better performance of blind individuals in monaural localization. Using positron-emission tomography (PET), we scanned blind and sighted persons as they discriminated between sounds originating from a single spatial position, but with different spectral profiles that simulated different spatial positions based on head-related transfer functions. We show here that a sub-group of early blind individuals showing superior monaural sound localization abilities performed significantly better than any other group on this spectral discrimination task. For all groups, performance was best for stimuli simulating peripheral positions, consistent with the notion that spectral cues are more helpful for discriminating peripheral sources. PET results showed that all blind groups showed cerebral blood flow increases in the occipital cortex; but this was also the case in the sighted group. A voxel-wise covariation analysis showed that more occipital recruitment was associated with better performance across all blind subjects but not the sighted. An inter-regional covariation analysis showed that the occipital activity in the blind covaried with that of several frontal and parietal regions known for their role in auditory spatial processing. Overall, these results support the notion that the superior ability of a sub-group of early-blind individuals to localize sounds is mediated by their superior ability to use spectral cues, and that this ability is subserved by cortical processing in the occipital cortex

    K-1 Small Satellite Missions

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    Kistler Aerospace Corporation is building the K-1, the world’s first fully reusable aerospace vehicle. By reusing each K-1 multiple times, Kistler plans to reduce the cost of access to space while providing a reliable launch on-demand capability to lowearth orbit and beyond. The K-1 is designed to carry a wide range of payloads to a variety of orbits. Kistler and Astrium Ltd. (formerly Matra Marconi Space UK) have initiated an effort to design reusable dispensers for multiple small payloads for use on the K-1. One of these dispensers may be used to deploy small satellites during the K-1’s flight test program. Kistler is investigating the feasibility of flying dedicated, multiple small payload missions. Such a mission may launch multiple small payloads from a single customer or small payloads from different customers. To facilitate ride-sharing opportunities, Kistler may issue an Announcement of Opportunity for multiple small payloads to fly to a predetermined orbit at a predetermined date. The orbit would be selected to be compatible with the requirements of as many small payload customers as possible. To avoid expensive recurring costs, small payloads would make use of standard interfaces and verification plans determined by Kistler. Kistler may employ the services of a broker to coordinate integration of multiple customers. If there is sufficient demand, Kistler can schedule regular fixed “departures” for small payloads. This would eliminate the need to match small payloads with a compatible primary payload customer, increasing the number of access to space opportunities open to small satellites

    Combined TRPC3 and TRPC6 blockade by selective small-molecule or genetic deletion inhibits pathological cardiac hypertrophy

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    Chronic neurohormonal and mechanical stresses are central fea-tures of heart disease. Increasing evidence supports a role forthe transient receptor potential canonical channels TRPC3 andTRPC6 in this pathophysiology. Channel expression for both is nor-mally very low but is increased by cardiac disease, and geneticgain- or loss-of-function studies support contributions to hypertro-phy and dysfunction. Selective small-molecule inhibitors remainscarce, and none target both channels, which may be useful giventhe high homology among them and evidence of redundant sig-naling. Here we tested selective TRPC3/6 antagonists (GSK2332255Band GSK2833503A; IC50,3–21 nM against TRPC3 and TRPC6) andfound dose-dependent blockade of cell hypertrophy signaling trig-gered by angiotensin II or endothelin-1 in HEK293T cells as well as inneonatal and adult cardiac myocytes. In vivo efficacy in mice andrats was greatly limited by rapid metabolism and high protein bind-ing, although antifibrotic effects with pressure overload were ob-served. Intriguingly, although gene deletion of TRPC3 or TRPC6alone did not protect against hypertrophy or dysfunction frompressure overload, combined deletion was protective, support-ing the value of dual inhibition. Further development of thispharmaceutical class may yield a useful therapeutic agent forheart disease management.Fil: Seo, Kinya. Johns Hopkins Medical Institutions. Department of Medicine; Estados UnidosFil: Rainer, Peter P.. Johns Hopkins Medical Institutions. Department of Medicine; Estados Unidos. Medical University of Graz. Department of Medicine; AustriaFil: Shalkey Hahn, Virginia. Johns Hopkins Medical Institutions. Department of Medicine; Estados UnidosFil: Lee, Dong-ik. Johns Hopkins Medical Institutions. Department of Medicine; Estados UnidosFil: Jo, Su-Hyun. Kangwon National University School of Medicine; Corea del Sur. Johns Hopkins Medical Institutions. Department of Medicine; Estados UnidosFil: Andersen, Asger. Aarhus University Hospital. Department of Cardiology; DinamarcaFil: Liu, Ting. Johns Hopkins Medical Institutions. Department of Medicine; Estados UnidosFil: Xu, Xiaoping. GlaxoSmithKline Heart Failure Discovery Performance Unit; Estados UnidosFil: Willette, Robert N.. GlaxoSmithKline Heart Failure Discovery Performance Unit; Estados UnidosFil: Lepore, John J.. GlaxoSmithKline Heart Failure Discovery Performance Unit; Estados UnidosFil: Marino, Joseph P.. GlaxoSmithKline Heart Failure Discovery Performance Unit; Estados UnidosFil: Birnbaumer, Lutz. ational Institute of Environmental Health Sciences; Estados Unidos. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Houssay. Instituto de Investigaciones BiomĂ©dicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones BiomĂ©dicas; ArgentinaFil: Schnackenberg, Christine G.. GlaxoSmithKline Heart Failure Discovery Performance Unit; Estados UnidosFil: Kass, David A.. Johns Hopkins Medical Institutions. Department of Medicine; Estados Unido

    Early Brain-Body Impact of Emotional Arousal

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    Current research in affective neuroscience suggests that the emotional content of visual stimuli activates brain–body responses that could be critical to general health and physical disease. The aim of this study was to develop an integrated neurophysiological approach linking central and peripheral markers of nervous activity during the presentation of natural scenes in order to determine the temporal stages of brain processing related to the bodily impact of emotions. More specifically, whole head magnetoencephalogram (MEG) data and skin conductance response (SCR), a reliable autonomic marker of central activation, were recorded in healthy volunteers during the presentation of emotional (unpleasant and pleasant) and neutral pictures selected from the International Affective Picture System (IAPS). Analyses of event-related magnetic fields (ERFs) revealed greater activity at 180 ms in an occipitotemporal component for emotional pictures than for neutral counterparts. More importantly, these early effects of emotional arousal on cerebral activity were significantly correlated with later increases in SCR magnitude. For the first time, a neuromagnetic cortical component linked to a well-documented marker of bodily arousal expression of emotion, namely, the SCR, was identified and located. This finding sheds light on the time course of the brain–body interaction with emotional arousal and provides new insights into the neural bases of complex and reciprocal mind–body links

    231Pa and 230Th in the Arctic Ocean 1991-2015: Changes in the Eurasian and Makarov Basins

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    230Th and 231Pa are produced in sea water by radioactive decay of Uranium isotopes (234U, 235U). Both are particle reactive and are scavenged onto settling particles. As 230Th is more particle reactive than 231Pa, their distribution in the water column and activity ratio give information about particle fluxes and circulation patterns and –intensities. Both particle fluxes and deep water circulation may respond to climatic changes in the Arctic Ocean. This study discusses temporal changes in radionuclide concentration in the context of climate change. We compare results from 1991 [1] 2007 and 2015. We present results of dissolved 231Pa and 230Th activities of samples collected in the Nansen-, Amundsenand Makarov Basins during GEOTRACES sections GIPY11 (2007, 4 stations), GN04 (2015, 10 stations) aboard RV Polarstern. Our discussion of factors controlling the 230Th and 231Pa distribution is supported by, dissolved CFC, dissolved iron and particulate 230Th and 231Pa (3 stations) collected during GEOTRACES section GN04. We find that distributions and concentrations of dissolved 231Pa and 230Th in the central Arctic Ocean have changed significantly since 1991. Dissolved 231Pa concentrations in the Makarov basin decreased by half within less than 20 years. These changes are discussed in the context of environmental changes, such as declining sea ice cover and related increase of particle fluxes or changing deep water circulation. [1] Scholten, J. C., et al. (1995). Deep-Sea Research II 42: 1519- 153
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