Publications

Copper is a required nutrient for life and particularly important to the brain and central nervous system. Indeed, copper redox activity is essential to maintaining normal physiological responses spanning neural signaling to metabolism, but at the same time copper misregulation is associat-ed with inflammation and neurodegeneration. As such, chemical probes that can track dynamic changes in copper with spatial resolution, espe-cially in loosely-bound, labile forms, are valuable tools to identify and characterize its contributions to healthy and disease states. In this report, we present an activity-based sensing (ABS) strategy for copper detection in live cells that preserves spatial information by a copper-dependent bioconjugation reaction. Specifically, we designed copper-directed acyl imidazole (CD) dyes that operate through copper-mediated activation of acyl imidazole electrophiles for subsequent labeling of proximal proteins at sites of elevated labile copper to provide a permanent stain that resists washing and fixation. To showcase the utility of this new ABS platform, we sought to characterize labile copper pools in the three main cell types in the brain: neurons, astrocytes, and microglia. Exposure of each of these cell types to physiologically relevant stimuli shows distinct changes in labile copper pools. Neurons display translocation of labile copper from somatic cell bodies to peripheral processes upon activation, whereas astrocytes and microglia exhibit global decreases and increases in intracellular labile copper pools, respectively, after exposure to inflam-matory stimuli. This work provides foundational information on cell type-dependent homeostasis of copper, an essential metal in the brain, as well as a starting point for the design of new activity-based probes for metals and other dynamic signaling and stress analytes in biology.

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTScreening of Homogeneous Catalysts by Fluorescence Resonance Energy Transfer. Identification of Catalysts for Room-Temperature Heck ReactionsJames P. Stambuli, Shaun R. Stauffer, Kevin H. Shaughnessy, and John F. HartwigView Author Information Department of Chemistry, Yale University P.O. Box 208107, New Haven, Connecticut 06520-8107 Cite this: J. Am. Chem. Soc. 2001, 123, 11, 2677–2678Publication Date (Web):February 22, 2001Publication History Received1 December 2000Published online22 February 2001Published inissue 1 March 2001https://pubs.acs.org/doi/10.1021/ja0058435https://doi.org/10.1021/ja0058435rapid-communicationACS PublicationsCopyright © 2001 American Chemical SocietyRequest reuse permissionsArticle Views6384Altmetric-Citations204LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (2)»Supporting Information Supporting Information SUBJECTS:Catalysts,Chemical reactions,Fluorescence resonance energy transfer,Heck reaction,Ligands Get e-Alerts

Abstract Using data from the Complete Nearby (redshift z host &lt; 0.02) sample of Type Ia Supernovae (CNIa0.02), we find a linear relation between two parameters derived from the B − V color curves of Type Ia supernovae: the color stretch s BV and the rising color slope <?CDATA ${s}_{0}^{* }(B-V)$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi>s</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>*</mml:mo> </mml:mrow> </mml:msubsup> <mml:mo stretchy="false">(</mml:mo> <mml:mi>B</mml:mi> <mml:mo>−</mml:mo> <mml:mi>V</mml:mi> <mml:mo stretchy="false">)</mml:mo> </mml:math> after the peak, and this relation applies to the full range of s BV . The s BV parameter is known to be tightly correlated with the peak luminosity, especially for fast decliners (dim Type Ia supernovae), and the luminosity correlation with s BV is markedly better than with the classic light-curve width parameters such as Δ m 15 ( B ). Thus, our new linear relation can be used to infer peak luminosity from <?CDATA ${s}_{0}^{* }$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi>s</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>*</mml:mo> </mml:mrow> </mml:msubsup> </mml:math> . Unlike s BV (or Δ m 15 ( B )), the measurement of <?CDATA ${s}_{0}^{* }(B-V)$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi>s</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>*</mml:mo> </mml:mrow> </mml:msubsup> <mml:mo stretchy="false">(</mml:mo> <mml:mi>B</mml:mi> <mml:mo>−</mml:mo> <mml:mi>V</mml:mi> <mml:mo stretchy="false">)</mml:mo> </mml:math> does not rely on a well-determined time of light-curve peak or color maximum, making it less demanding on the light-curve coverage than past approaches.

Deccan volcanism in India covered more than 1 million square km and reached a maximum thickness of about 3 km, as presently preserved in the Western Ghats volcanic lava piles. Volcanic activity started at about 66.4 Ma (Jawhar formation) and ended at about 65.5 Ma (Mahabaleshwar unit; Renne et al., 2015). Deccan volcanism straddled the Cretaceous-Paleogene boundary (ca. 66.0 Ma) and possibly contributed to the end-Cretaceous mass extinction event through emission of gases such as SO2, CO2, Cl, F that may have triggered global climate changes. Severe pollution by volcanic gases is supported by the high S and Cl contents (up to 1400 and up to 900 ppm, respectively; Self et al., 2008) measured in a few olivine- and plagioclase-hosted melt inclusions from the Jawhar, Neral, and Thakurvadi Formations (early lava flows, ca. 66.3-66.4 ± 0.1 Ma; Renne et al., 2015) and by magmatic S contents (up to 1800 ppm; Callegaro et al., 2014) calculated from S measurements in clinopyroxenes from the Mahabaleshwar unit (ca. 65.5 ± 0.1; Schoene et al., 2015). Here, we present new analyses of S, Cl, and F, obtained by ion-probe and synchrotron light micro-fluorescence analyses on clinopyroxenes and plagioclase phenocrysts from ?al? lava flow units of the Western Ghats. The volatile contents of the host magmas have been calculated from recently published clinopyroxene/basalt partition coefficients. These new data will describe the time-related variation of volatile elements hosted and eventually emitted by Deccan lavas and shed light on their environmental impact. References: Callegaro S. et al. (2014). Geology 42, 895-898. Renne P.R. et al. (2015). Science 350, 76-78. Schoene B. et al. (2015). Science 347, 192-184. Self S. et al. (2008). Science 319, 1654-1657.

Memory caches continue to be a critical component to many systems. In recent years, there has been larger amounts of data into main memory, especially in shared environments such as the cloud. The nature of such environments requires resource allocations to provide both performance isolation for multiple users/applications and high utilization for the systems. We study the problem of fair allocation of memory cache for multiple users with shared files. We find that, surprisingly, no memory allocation policy can provide all three desirable properties (isolation-guarantee, strategy-proofness and Pareto-efficiency) that are typically achievable by other types of resources, e.g., CPU or network. We also show that there exist policies that achieve any two of the three properties. We find that the only way to achieve both isolation-guarantee and strategy-proofness is through blocking, which we efficiently adapt in a new policy called FairRide. We implement FairRide in a popular memory-centric storage system using an efficient form of blocking, named as expected delaying, and demonstrate that FairRide can lead to better cache efficiency (2.6× over isolated caches) and fairness in many scenarios.

The ubiquity of vanadium oxo complexes in the V+ and IV+ oxidation states has contributed to a comprehensive understanding of their electronic structure and reactivity. However, despite being predicted to be stable by ligand-field theory, the isolation and characterization of a well-defined terminal mononuclear vanadium(III) oxo complex has remained elusive. We present the synthesis and characterization of a unique terminal mononuclear vanadium(III) oxo species supported by the pentadentate polypyridyl ligand 2,6-bis[1,1-bis(2-pyridyl)ethyl]pyridine (PY5Me2). Exposure of [VII(NCCH3)(PY5Me2)]2+ (1) to either dioxygen or selected O-atom-transfer reagents yields [VIV(O)(PY5Me2)]2+ (2). The metal-centered one-electron reduction of this vanadium(IV) oxo complex furnishes a stable, diamagnetic [VIII(O)(PY5Me2)]+ (3) species. The vanadium(III) oxo species is unreactive toward H- and O-atom transfer but readily reacts with protons to form a putative vanadium hydroxo complex. Computational results predict that further one-electron reduction of the vanadium(III) oxo species will result in ligand-based reduction, even though pyridine is generally considered to be a poor π-accepting ligand. These results have implications for future efforts toward low-valent vanadyl chemistry, particularly with regard to the isolation and study of formal vanadium(II) oxo species.