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A SEARCH FOR VERY LOW-LUMINOSITY OBJECTS IN GOULD BELT CLOUDS
Kim, Mi-Ryang,Lee, Chang Won,Dunham, Michael M.,Evans II, Neal J.,Kim, Gwanjeong,Allen, Lori E. American Astronomical Society 2016 The Astrophysical journal Supplement series Vol.225 No.2
<P>We present the results of a search for Very Low-Luminosity Objects (VeLLOs) in the Gould Belt (GB) clouds using infrared and sub-millimeter (sub-mm) data from 1.25 to 850 mu m and our N2H+ (J = 1-0) observations. We modified the criteria by Dunham et al.. to select the VeLLOs in the GB clouds, finding 95 VeLLO candidates, 79 of which are newly identified in this study. Out of 95 sources, 44 were detected in both sub-mm continuum and N2H+ emission and were classified as Group A (the VeLLOs), and 51 sources detected in either sub-mm emission or N2H+ emission were classified with Group B as candidate VeLLOs. We find that these VeLLOs and the candidates are forming in environments different from those of the likely VeLLOs. Seventy-eight sources are embedded within their molecular clouds, and thus are likely VeLLOs forming in a dense environment. The remaining 17 sources are located in low-level extinction regions (A(V) < 1) connected to the clouds, and can be either background sources or candidate substellar objects forming in an isolated mode. The VeLLOs and the candidates are likely more luminous and their envelopes tend to be more massive in denser environments. The VeLLOs and the candidates are more populous in the clouds where more YSOs form, indicating that they form in a manner similar to that of normal YSOs. The bolometric luminosities and temperatures of the VeLLOs are compared to predictions of episodic accretion models, showing that the low luminosities for most VeLLOs can be well explained by their status in the quiescent phases of a cycle of episodic mass accretion.</P>
Analytical capabilities of mass spectrometry imaging and its potential applications in food science
Li, B.,Dunham, S.J.B.,Dong, Y.,Yoon, S.,Zeng, M.,Sweedler, J.V. Elsevier Trends Journals 2016 Trends in food science & technology Vol.47 No.-
<P>Background: Mass spectrometry imaging (MSI) is an untargeted and label-free chemical imaging technique that allows for the analysis of hundreds to thousands of molecules in a single experiment. Over the last two decades, MSI has become common in the medicinal, pharmaceutical, and botanical research communities, but has been applied less frequently in food science research. As an emerging 'molecular microscope', MSI offers unparalleled advantages for exploration of the spatio-chemical information from various food materials. It allows researchers to localize biomarkers of food origin and authenticity, characterize nutrients or chemical contaminants affecting human health, and ultimately, extend our understanding of food factors at the molecular level. Scope and approach: This review focuses on the predominant MSI ionization technologies and summarizes their application to studies involving food science, including the imaging of food metabolites, elements, naturally occurring toxic constituents, and exogenous contaminates. Technical considerations associated with sample preparation, MALDI matrix choice and application, data processing, analyte identification, and spatial resolution are discussed, as are the future outlooks for MSI in food science. Key findings and conclusions: MSI offers unparalleled chemical specificity for multiplexed analysis of the spatial distribution of nutrients, elements, and contaminants in food; information that is difficult or impossible to acquire with traditional staining or label-based methodologies. The unique spatio-chemical insights acquired with MSI have proven essential for understanding metabolic origin and change, and for visualization of exogenous substances having relevance to food quality and safety. (C) 2015 Elsevier Ltd. All rights reserved.</P>