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Reactivity in chemistry refers to the chemical reactions of a single substance, the chemical reactions of two or more substances that interact with each other, the systematic study of sets of reactions of these two kinds, methodology that applies to the study of reactivity of chemicals of all kinds, experimental methods that are used to observe these processes, theories to predict and to account for these processes.The chemical reactivity of a single substance covers its behaviour in which it: Decomposes Forms new substances by addition of atoms from another reactant or reactants Interacts with two or more other reactants to form two or more productsThe chemical reactivity of a substance can refer to the variety of circumstances in which it reacts, in combination with the: Variety of substances with which it reacts, Equilibrium point of the reaction Rate of the reactionThe term reactivity is related to the concepts of chemical stability and chemical compatibility. Wikipedia.


Martinet N.,University of Nice Sophia Antipolis | Michel B.Y.,University of Nice Sophia Antipolis | Bertrand P.,Reactivity | Benhida R.,University of Nice Sophia Antipolis
MedChemComm | Year: 2012

Methylation catalyzed by the DNA methyltransferases affects the C5 position of cytosine residues in DNA. This physiological process is active from the embryo conception, throughout all its developmental steps, and also later for the maintenance of the adult organism. Excess methylated cytosine in tumor suppressor genes is a consistent hallmark of human cancers. However, DNA methylation variation is now acknowledged to significantly contribute to genetic and common diseases. DNA methyltransferases became attractive therapeutic targets as DNA demethylation, in vitro, brought cancer cell differentiation and apoptosis. Inhibitors are already in use, alone or in combination, to treat myeloid malignancies, while clinical assays are ongoing for other diseases. DNA methylation and histone modifications are intimately correlated with epigenetic heritable modifications of gene expression that are independent of changes in the genetic sequence. Common initiatives for epigenetic research have built public databases with useful resources. The recent discovery of 5-hydroxymethyl cytosine has added new questions and challenges for the epigenome community. We review here knowledge about DNA methylation to provide researchers with the information needed to make more active inhibitors for the benefit of patients. Because of space limitations, many important works cannot be cited. We refer the reader to reviews containing these references. © 2012 The Royal Society of Chemistry. Source


Roy A.,University of Florida | Segal C.,University of Florida | Joly C.,French National Center for Scientific Research | Joly C.,Reactivity
AIAA Journal | Year: 2013

Density and density-gradient values were quantified for subcritical to supercritical jets, and a novel method was applied for calculating the core lengths using the structures detected across the entire jet center plane. Jet spreading angles were also calculated, and a model was proposed for the spreading angle dependence on the chamber-toinjectant density ratio. A detailed comparison was provided with existing theoretical models and experimental data for both core lengths and spreading angles. Single and binary species mixtures were used to study the injection and mixing characteristics of both subcritical and supercritical jets. Copyright © 2013 by the American Institute of Aeronautics and Astronautics, Inc. Source


News Article | August 9, 2012
Site: techcrunch.com

Greylock Partners announced tonight that it has added a new member to its team, with Mike Hanson joining the firm this week as an Entrepreneur-in-Residence. Hanson joins Greylock from Mozilla, where he has been a principal engineer at Mozilla Labs for the last three years, playing a central role in conceiving the company’s distributed identity verification system, also known as BrowserID, and developing APIs and apps for Firefox’s apps platform — among other things. Prior to Mozilla, Hanson was a principal engineer at Cisco, working on app delivery, particularly device virtualization, clustering, as well as data center strategy. Hanson also co-founded and was the chief architect at Reactivity and spent several years at the Apple Research Lab working on Sherlock, perhaps better known as the precursor to Spotlight. He also counts 16 patents to his name. Greylock’s former Entrepreneurs-in-Residence include Josh Silverman, the President of Consumer Services at American Express and former CEO of Skype, LinkedIn CEO Jeff Weiner and Google VP of Engineering Venkat Panchapakesan, among others. Michael Callahan, the former CTO of PolyServe, is also currently an EIR at Greylock. John Lilly, a partner at Greylock and the former CEO of Mozilla who worked with Hanson at Mozilla among other places, penned the firm’s announcement today — which you can read here. Copied below: It’s with great pleasure that I get to write this post letting you know that Mike Hanson has joined Greylock this week as an Entrepreneur-in-Residence. He’s what I call an “Anytime, Anything, Anywhere” person: someone who I would drop whatever I’m doing to get a chance to work with him on anything, anytime, anywhere. I’ve been very fortunate to work with Mike many times, dating all the way back to his time at Stanford, where he studied computer science and interaction design. When he was there, Mike did seminal work on early web search, and worked in some technology for the company that would eventually become Excite. After that Mike worked at the Apple Research Lab on Sherlock (precursor to Spotlight) before co-founding Reactivity with me and a couple of others. He’s worked on startups at the very beginning, but also massive organizations like Apple & Cisco. Most recently he’s been at Mozilla, working on web-scale identity and application systems. I’m particularly excited he’s come to Greylock now because we’re in such an incredibly fertile innovation period. The widespread adoption of both mobile and cloud technology, and their sudden pervasiveness have created a massive opportunity to reinvent huge industries, and to rethink many of the ways we live our lives and spend time with each other. Mike is an especially perfect person to think through these opportunities because he’s a “full stack” thinker, from deep server-side technologies all the way through to engaging and durable and useful user experiences. It seems to me that there’s never been a better time to work on “thick innovations” that marry the best of deep technology and amazing user experiences. There are few people in the world who can think like that better than Mike, so we feel very fortunate to have him here at Greylock, thinking about and building the next big thing.


Symoneaux R.,University of Angers | Baron A.,Reactivity | Marnet N.,Reactivity | Bauduin R.,IFPC | Chollet S.,Lille Catholic University
LWT - Food Science and Technology | Year: 2014

The impact of the degree of polymerization and of the concentration of procyanidins in a model solution of French cider was investigated. Four purified fractions of procyanidins at three concentrations were added in a solution containing water, ethanol, fructose and malic acid. The four studied sensory characteristics (bitterness, astringency, sweetness and sourness) were modified according to the concentration of procyanidins. The degree of polymerization (DP) of procyanidins influenced only bitterness and astringency but this impact was not the same for all concentrations. Despite the fact that pH, fructose and malic acid concentrations were the same in all samples, the perception of sweetness and sourness were modified according to the concentration of procyanidins. © 2013 Elsevier Ltd. Source


Schlegel M.L.,Reactivity | Schlegel M.L.,CNRS Laboratory for Analysis and Modelling for Biology and Environment | Bataillon C.,CEA Saclay Nuclear Research Center | Blanc C.,Reactivity | And 2 more authors.
Environmental Science and Technology | Year: 2010

To understand the process governing iron corrosion in clay over centuries, the chemical and mineralogical properties of solids formed by free or anodically activated corrosion of iron in water-saturated clay at 90 °C over 4 months were probed using microscopic and spectroscopic techniques. Free corrosion led to the formation of an internal discontinuous thin (<3 μm thick) magnetite layer, an external layer of Ferich phyllosilicate, and a clay transformation layer containing Cadoped siderite (Ca0.2Fe0.8CO 3). The thickness of corroded iron equaled -5-7 μm, consistent with previous studies. Anodic polarization resulted in unequally distributed corrosion, with some areas corrosion-free and others heavily corroded. Activated corrosion led to the formation of an inner magnetite layer, an intermediate Fe2CO3(OH)2 (chukanovite) layer, an outer layer of Fe-rich 7 Å-phyllosilicate, and a transformed matrix layer containing siderite (FeCO3). The corroded thickness was estimated to 85 μm, less than 30% of the value expected from the supplied anodic charge. The difference was accounted for by reoxidation at the anodically polarized surface of cathodically produced H2(g). Thus, free or anodically activated corroding conditions led to structurally similar interfaces, indicating that anodic polarization can be used to probe the long-term corrosion of iron in clay. Finally, corrosion products retained only half of Fe oxidized by anodic activation. Missing Fe probably migrated in the clay, where it could interact with radionuclides released by alteration of nuclear glass. © 2010 American Chemical Society. Source

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