Oncology & Cancer

Study shows why many cancer cells need to import fat

Columbia and MIT researchers are revealing the surprising reasons why cancer cells are often forced to rely on fat imports, a finding that could lead to new ways to understand and slow down tumor growth.

Health

The promise of meditation for the heart and mind

Meditation, as a religious practice or mystic experience, may be as old as humanity. Evidence of its use dates back as far as 7,000 years, and some scholars speculate it might have begun among people sitting in caves, gazing ...

Oncology & Cancer

Boosting the immune response against cancer

T cells are usually good at eliminating diseased cells, but they seem to fail when it comes to tumor cells. In JCI Insight, MDC teams led by Armin Rehm and Uta Höpken describe what inhibits this immune function, and how ...

Medical research

Regenerating the heart after an attack

Heart attacks are damaging, and the severity depends on how long blood flow has been interrupted; when temporarily deprived of oxygen, heart cells die. In addition, the heart can't rebuild its own tissue, leading to its failure, ...

Cardiology

New discoveries in lupus research

Two separate findings by a University of Houston nationally recognized expert in systemic lupus erythematosus (SLE or lupus), a chronic autoimmune disease that affects multiple organs including the kidneys, skin, joints and ...

Genetics

Olfactory neurons adapt to the surrounding environment

Olfactory receptors, present on the surface of sensory neurons in the nasal cavity, recognize odorant molecules and relay this information to the brain. How do these neurons manage to detect a large variability of signals ...

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Molecule

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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