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Mycobacterium tuberculosis (stained red) in tissue (blue).. Acid-fastness is a physical property of certain bacterial and eukaryotic cells, as well as some sub-cellular structures, specifically their resistance to decolorization by acids during laboratory staining procedures.
In molecular biology, the HdeA family of proteins (HNS (histone-like nucleoid structuring)-dependent expression A) is a stress response protein family found in highly acid resistant bacteria such as Shigella flexneri and Escherichia coli, but which is lacking in mildly acid tolerant bacteria such as Salmonella. [1]
For example, acetic acid is a weak acid which has a = 1.75 x 10 −5. Its conjugate base is the acetate ion with K b = 10 −14 /K a = 5.7 x 10 −10 (from the relationship K a × K b = 10 −14), which certainly does not correspond to a strong base. The conjugate of a weak acid is often a weak base and vice versa.
The chemical resistance of a material or surface can be determined in compliance with ISO 2812 Paints and varnishes – Determination of resistance to liquids – Part 1: Immersion in liquids other than water (ISO 2812-1:2007 [1]); German Version EN ISO 2812-1:2007 or Part 4: Spotting methods (ISO 2812-4:2007 [2]); German Version EN ISO 2812-4:2007.
The use of acid-resistant gloves and face shield is recommended for safe handling; fume hoods are another effective control of such substances. [ 4 ] Water-reactive substances are classified as R2 under the UN classification system and as Hazard 4.3 by the United States Department of Transportation .
Tartrate-resistant acid phosphatase (TRAP or TRAPase), also called acid phosphatase 5, tartrate resistant (ACP5), is a glycosylated monomeric metalloprotein enzyme expressed in mammals. [5] It has a molecular weight of approximately 35kDa, a basic isoelectric point (7.6–9.5), and optimal activity in acidic conditions.
As part of their adaptation from marine life, terrestrial plants began producing non-marine antioxidants such as ascorbic acid (), polyphenols, and tocopherols.The evolution of angiosperm plants between 50 and 200 million years ago resulted in the development of many antioxidant pigments – particularly during the Jurassic period – as chemical defences against reactive oxygen species that ...
Water-insoluble and relatively resistant to hydrolytic degradation. This differentiates PHB from most other currently available biodegradable plastics, which are either water-soluble or moisture-sensitive. Good oxygen permeability. Good ultra-violet resistance but poor resistance to acids and bases.