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Small molecules (up to ca. 1000 atoms) usually form better-ordered crystals than large molecules, and thus it is possible to attain lower R-factors. In the Cambridge Structural Database of small-molecule structures, more than 95% of the 500,000+ crystals have an R-factor lower than 0.15, and 9.5% have an R-factor lower than 0.03.
An overview of the different components included in the field of chemical biology. Chemical biology is a scientific discipline between the fields of chemistry and biology.The discipline involves the application of chemical techniques, analysis, and often small molecules produced through synthetic chemistry, to the study and manipulation of biological systems. [1]
RNA can also act as a hereditary molecule, which encouraged Walter Gilbert to propose that in the distant past, the cell used RNA as both the genetic material and the structural and catalytic molecule rather than dividing these functions between DNA and protein as they are today; this hypothesis is known as the "RNA world hypothesis" of the ...
The study of abiogenesis aims to determine how pre-life chemical reactions gave rise to life under conditions strikingly different from those on Earth today. It primarily uses tools from biology and chemistry , with more recent approaches attempting a synthesis of many sciences.
1998 – Mello and Fire publish their work on RNAi in c.elegans, for which they shared the 2006 Nobel Prize in Physiology or Medicine. 1999 – Researchers at the Institute for Human Gene Therapy at the University of Pennsylvania accidentally kill Jesse Gelsinger during a clinical trial of a gene therapy technique, leading the FDA to halt ...
Also acid ionization constant or acidity constant. A quantitative measure of the strength of an acid in solution expressed as an equilibrium constant for a chemical dissociation reaction in the context of acid-base reactions. It is often given as its base-10 cologarithm, p K a. acid–base extraction A chemical reaction in which chemical species are separated from other acids and bases. acid ...
The prototypical Schrock catalyst is (R"O) 2 (R'N)Mo(CHR) where R = tert-butyl, R' = 2,6-diisopropylphenyl, and R" = C(Me)(CF 3) 2. Such catalysts are now commercially available from such major suppliers as Sigma-Aldrich and XiMo, inc., which is now owned by Verbio, AG, and are used frequently in synthetic applications of olefin metathesis in ...
Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes can occur. The substance (or substances) initially involved in a chemical reaction are called reactants or reagents.