Researchers from the Universidad de Santiago de Chile and the University of Notre Dame, working with machine learning, have devised a method to identify organic compounds based on the refractive index at a single optical ...
How did life come about? The answer to this question goes to the very heart of our existence on planet Earth.
Astrobiology
Mar 25, 2023
0
48
A new NASA mission to Saturn's giant moon, Titan, is due to launch in 2027. When it arrives in the mid-2030s, it will begin a journey of discovery that could bring about a new understanding of the development of life in the ...
Astrobiology
Mar 17, 2023
0
442
Researchers have analyzed samples of the asteroid Ryugu collected by the Japanese Space Agency's Hayabusa2 spacecraft and found uracil, one of the informational units that make up RNA, the molecules that contain the instructions ...
Astrobiology
Mar 21, 2023
2
410
Stanford University researchers have developed a computational method for identifying where cells are situated in a sample when capturing spatial transcriptomics. The method combines data from spatial transcriptions and a ...
UC Riverside scientists have significantly advanced the race to control plant responses to temperature on a rapidly warming planet. Key to this breakthrough is miRNA, a molecule nearly 200,000 times smaller than the width ...
Plants & Animals
Mar 23, 2023
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62
A team of chemists at MIT has found that using peptides instead of DNA fragments to tag small molecules can speed up the drug discovery process. Their research is published in the journal Science.
Fluorescence is a fascinating natural phenomenon. It is based on the fact that certain materials can absorb light of a certain wavelength and then emit light of a different wavelength. Fluorescent materials play an important ...
Biochemistry
Mar 10, 2023
1
179
The peculiar topological properties of some forms of matter have been researched for decades. Now, researchers at the Institute of Science and Technology Austria (ISTA) have discovered topological properties of simple diatomic ...
Condensed Matter
Mar 10, 2023
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229
The amount of carbon dioxide in the atmosphere increases daily with no sign of stopping or slowing. Too much of civilization depends on the burning of fossil fuels, and even if we can develop a replacement energy source, ...
Analytical Chemistry
Mar 14, 2023
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90
A molecule is defined as a sufficiently stable, electrically neutral group of at least two atoms in a definite arrangement held together by very strong (covalent) chemical bonds. Molecules are distinguished from polyatomic ions in this strict sense. In organic chemistry and biochemistry, the term molecule is used less strictly and also is applied to charged organic molecules and biomolecules.
In the kinetic theory of gases the term molecule is often used for any gaseous particle regardless of its composition. According to this definition noble gas atoms are considered molecules despite the fact that they are composed of a single non-bonded atom.
A molecule may consist of atoms of a single chemical element, as with oxygen (O2), or of different elements, as with water (H2O). Atoms and complexes connected by non-covalent bonds such as hydrogen bonds or ionic bonds are generally not considered single molecules.
No typical molecule can be defined for ionic crystals (salts) and covalent crystals (network solids), although these are often composed of repeating unit cells that extend either in a plane (such as in graphene) or three-dimensionally (such as in diamond or sodium chloride). The theme of repeated unit-cellular-structure also holds for most condensed phases with metallic bonding. In glasses (solids that exist in a vitreous disordered state), atoms may also be held together by chemical bonds without any definable molecule, but also without any of the regularity of repeating units that characterises crystals.
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