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Blood urea nitrogen (BUN) is a medical test that measures the amount of urea nitrogen found in blood. The liver produces urea in the urea cycle as a waste product of the digestion of protein . Normal human adult blood should contain 7 to 18 mg/dL (0.388 to 1 mmol/L) of urea nitrogen. [ 1 ]
In medicine, the urea-to-creatinine ratio (UCR [1]), known in the United States as BUN-to-creatinine ratio, is the ratio of the blood levels of urea (mmol/L) and creatinine (Cr) (μmol/L). BUN only reflects the nitrogen content of urea (MW 28) and urea measurement reflects the whole of the molecule (MW 60), urea is just over twice BUN (60/28 ...
In general, any particular instrument will operate over a small portion of this total range because of the different techniques used to measure different portions of the spectrum. Below optical frequencies (that is, at microwave and radio frequencies), the spectrum analyzer is a closely related electronic device. Spectrometers are used in many ...
A blood test is a laboratory analysis performed on a blood sample that is usually extracted from a vein in the arm using a hypodermic needle, or via fingerprick. Multiple tests for specific blood components, such as a glucose test or a cholesterol test , are often grouped together into one test panel called a blood panel or blood work .
F-center in an NaCl crystal. An F-center or color center or Farbe center (from the original German Farbzentrum, where Farbe means color and zentrum means center) is a type of crystallographic defect in which an anionic vacancy in a crystal lattice is occupied by one or more unpaired electrons.
Other tests are esoteric in nature—they are performed less frequently than other tests, and are generally more expensive and time-consuming to perform. Even so, the current [ when? ] shortage of qualified clinical laboratory professionals [ 8 ] has spurred manufacturers to develop automated systems for even these rarely performed tests.
Analyses are performed by using a conventional scanning spectrophotometer and the usual laboratory cuvette (special vial) that fits into the sample cavity of the instrument. [7] Fingerprints and droplets of water disrupt light rays during measurement, so low-lint gauze or cloth may be used to wipe clean the outer surface of a cuvette before use ...
The optical properties of a material define how it interacts with light. The optical properties of matter are studied in optical physics (a subfield of optics ) and applied in materials science . The optical properties of matter include: