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Cotinine has an in vivo half-life of approximately 20 hours, and is typically detectable for several days (up to one week) after the use of tobacco. The level of cotinine in the blood, saliva, and urine is proportionate to the amount of exposure to tobacco smoke, so it is a valuable indicator of tobacco smoke exposure, including secondary (passive) smoke. [14]
Myoglobin sketch Alpha helix. 1958 – Myoglobin was the very first crystal structure of a protein molecule. [2] Myoglobin cradles an iron-containing heme group that reversibly binds oxygen for use in powering muscle fibers, and those first crystals were of myoglobin from the sperm whale, whose muscles need copious oxygen storage for deep dives.
A positive test result for sepiolite turns purple. [8] This can distinguish calcite from sepiolite in the field: sepiolite reacts to change the methyl orange to a shade of purple where calcite remains orange. [9] [10] When first extracted, sepiolite is soft. However, it hardens on exposure to sun heat or when dried in a warm room. [7]
For over 150 years, scientists from all around the world have known about the crystallization of protein molecules. [6]In 1840, Friedrich Ludwig Hünefeld accidentally discovered the formation of crystalline material in samples of earthworm blood held under two glass slides and occasionally observed small plate-like crystals in desiccated swine or human blood samples.
When sugar crystals are crushed, tiny electrical fields are created, separating positive and negative charges that create sparks while trying to reunite. Wint-O-Green Life Savers work especially well for creating such sparks, because wintergreen oil ( methyl salicylate ) is fluorescent and converts ultraviolet light into blue light .
Crystal structure of OsO 4 [4] Osmium(VIII) oxide forms monoclinic crystals. [4] [8] It has a characteristic acrid chlorine-like odor. The element name osmium is derived from osme, Greek for odor. OsO 4 is volatile: it sublimes at room temperature. It is soluble in a wide range of organic solvents.
A toxic effect causing purpling of the face was seen in these tests. A subject given 1 mg reported "a tight feeling in the chest" and prickling "as if he had been jabbed by needles." This was accompanied by a "fleeting sensation of pain in both thighs and a mild nausea." [46] Another subject given 2 mg reported "tightness in his throat."
A crystal of Bence Jones protein. Bence Jones protein is a monoclonal globulin protein or immunoglobulin light chain found in the urine, with a molecular weight of 22–24 kDa. [1] Detection of Bence Jones protein may be suggestive of multiple myeloma, [2] or Waldenström's macroglobulinemia. [citation needed]