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Tetracyclines are generally used in the treatment of infections of the urinary tract, respiratory tract, and the intestines and are also used in the treatment of chlamydia, especially in patients allergic to β-lactams and macrolides; however, their use for these indications is less popular than it once was due to widespread development of resistance in the causative organisms.
Tetracycline hydrochloride is available as yellow crystalline powder. Since tetracycline is absorbed into bone, it is used as a marker of bone growth for biopsies in humans. Tetracycline labeling is used to determine the amount of bone growth within a certain period of time, usually a period around 21 days.
The structure of tetracenomycin C was established by chemical and spectroscopic methods. [3] The three hydroxy groups, at C-4, C-4a, and C-12a, are cis to each other. The two at C-4a and C-12a are involved in intramolecular hydrogen bonding to the carbonyl oxygen atoms at C-5 and C-1, respectively.
An ideal crystal has every atom in a perfect, exactly repeating pattern. [19] However, in reality, most crystalline materials have a variety of crystallographic defects: places where the crystal's pattern is interrupted. The types and structures of these defects may have a profound effect on the properties of the materials.
In crystalline materials the addition of particles works to impede dislocation motion and strengthen the material. However, for many semi-crystalline polymers particle fillers weaken the material. It has been suggested that for particles to have a toughening effect in polymers the interparticle matrix ligament thickness must be smaller than a ...
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In crystallography, crystal structure is a description of ordered arrangement of atoms, ions, or molecules in a crystalline material. [1] Ordered structures occur from intrinsic nature of constituent particles to form symmetric patterns that repeat along the principal directions of three-dimensional space in matter.
Crystallography is used by materials scientists to characterize different materials. In single crystals, the effects of the crystalline arrangement of atoms is often easy to see macroscopically because the natural shapes of crystals reflect the atomic structure. In addition, physical properties are often controlled by crystalline defects.