Discovering new biological targets is a critical part of our ongoing battle against diseases. Over the years, scientists have made impressive progress towards the understanding of biological systems, constantly identifying ...
Biochemistry
Apr 18, 2019
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54
Nearly every fundamental biological process necessary for life is carried out by proteins. They create and maintain the shapes of cells and tissues; constitute the enzymes that catalyze life-sustaining chemical reactions; ...
Biochemistry
Apr 17, 2019
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503
In 2015, a fluorosurfactant known by the trade name "GenX" made headlines when researchers discovered it and related compounds in the Cape Fear River of North Carolina, a source of drinking water for many residents of the ...
Environment
Apr 17, 2019
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Plant regeneration can occur via formation of a mass of pluripotent cells. The process of acquisition of pluripotency involves silencing of genes to remove original tissue memory and priming for activation by external input. ...
Plants & Animals
Apr 17, 2019
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7
A large team of researchers affiliated with several institutions in China has learned more about a type of snailfish that lives in the deepest parts of the ocean. In their paper published in the journal Nature Ecology and ...
A team of researchers affiliated with several institutions in Japan has found that soldier aphids willingly sacrifice their own lives when they attempt to protect their colony from predators. In their paper published in Proceedings ...
Where the village smithy once stood now stands an algorithm, its mighty mathematical hammer pounding proteins into shape.
Biochemistry
Apr 15, 2019
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45
Researchers say mercury buried in ancient rock provides the strongest evidence yet that volcanoes caused the biggest mass extinction in the history of the Earth.
Earth Sciences
Apr 15, 2019
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395
Like humans and animals, plants defend themselves against pathogens with the help of their immune system. But how do they activate their cellular defenses? Researchers at the Technical University of Munich (TUM) have now ...
Plants & Animals
Apr 12, 2019
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113
Researchers from the Universities of Konstanz (Germany), Leeds (U.K.) and Stanford (U.S.) have discovered that the nascent polypeptide-associated complex (NAC) prevents the aggregation of proteins associated with several ...
Cell & Microbiology
Apr 11, 2019
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50
An acid (from the Latin acidus/acēre meaning sour) is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red. Chemicals or substances having the property of an acid are said to be acidic.
Common examples of acids include acetic acid (in vinegar), sulfuric acid (used in car batteries), and tartaric acid (used in baking). As these three examples show, acids can be solutions, liquids, or solids. Gases such as hydrogen chloride can be acids as well. Strong acids and some concentrated weak acids are corrosive, but there are exceptions such as carboranes and boric acid.
There are three common definitions for acids: the Arrhenius definition, the Brønsted-Lowry definition, and the Lewis definition. The Arrhenius definition states that acids are substances which increase the concentration of hydronium ions (H3O+) in solution. The Brønsted-Lowry definition is an expansion: an acid is a substance which can act as a proton donor. Most acids encountered in everyday life are aqueous solutions, or can be dissolved in water, and these two definitions are most relevant. The reason why pHs of acids are less than 7 is that the concentration of hydronium ions is greater than 10−7 moles per liter. Since pH is defined as the negative logarithm of the concentration of hydronium ions, acids thus have pHs of less than 7. By the Brønsted-Lowry definition, any compound which can easily be deprotonated can be considered an acid. Examples include alcohols and amines which contain O-H or N-H fragments.
In chemistry, the Lewis definition of acidity is frequently encountered. Lewis acids are electron-pair acceptors. Examples of Lewis acids include all metal cations, and electron-deficient molecules such as boron trifluoride and aluminium trichloride. Hydronium ions are acids according to all three definitions. Interestingly, although alcohols and amines can be Brønsted-Lowry acids as mentioned above, they can also function as Lewis bases due to the lone pairs of electrons on their oxygen and nitrogen atoms.
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