Vitreous attachment

Table 1.1 Comparison of metallurgical, polymeric, and vitreous attachment methods...

Comparison of polymer adhesives with metallurgical and vitreous attachment materials... 

Table 1.1. Comparison of Metallurgical, Polymeric, and Vitreous Attachment Methods...

COMPARISON OF POLYMER ADHESIVES WITH METALLURGICAL AND VITREOUS ATTACHMENT MATERIALS... 

Dental silicate cement was also variously known in the past as a translucent, porcelain or vitreous cement. The present name is to some extent a misnomer, probably attached to the cement in the mistaken belief that it was a silicate cement, whereas we now know that it is a phosphate-bonded cement. It is formed by mixing an aluminosilicate glass with an aqueous solution of orthophosphoric acid. After preparation the cement paste sets within a few minutes in the mouth. It is, perhaps, the strongest of the purely inorganic cements when prepared by conventional methods, with a compressive strength that can reach 300 MPa after 24 hours (Wilson et al, 1972). 

To decompose it, place equal parts of metal [potassium] and very pure, vitreous boracic acid in a copper tube to which a tube of bent glass is attached. Place the copper tube in a small furnace, with the end of the glass tube in a flask of mercury When the apparatus is ready, heat the copper tube gradually until it becomes faintly red keep it in this condition for several minutes then, the operation being ended, allow it to cool and take out the material. 

IXa e Cartilage, vitreous humor Minor, contains attached glycosamino- ... 

Coming Code 77 40 attachment to vitreous silica [SILICA - VITREOUS SILICA] (Vol 21)... 

Hyaluronan is the most common negatively charged glycosaminoglycan in the human vitreous humor, and is known to interact with polymeric and liposomal DNA complexes, where hyaluronan solutions have been shown to decrease the cellular uptake of complexes.This is useful for enhancing the availability and retention time of drugs administered to the eye. It is immunoneutral, which makes it useful for the attachment of biomaterials for use in tissue engineering and drug delivery... 

The CVD reactor consists of a vitreous silica tube of about 20 cm in diameter (8") and a height of 30.5 cm (1 ft). The filament was made from tantalum wire with 0.5 mm diameter and attached to water-cooled copper electrodes. Heat treatment in a methane atmosphere produces a thin layer of tantalum carbide that protects the sample from contamination with metallic tantalum. A gas-leaking unit allows the introduction of various gases and their mixtures into the reaction chamber under controlled pressure. Before introducing or changing the gas the unit s internal pressure was reduced by a mechanical pump to about 0.1 Pa. 

Vitreous materials comprise a third type of attachment material. Glasses may be used to seal lids to packages for hermetic enclosures. Silver-glass pastes have been developed for die attachment. They have high thermal and electrical conductivities and are used extensively for single die attachment in single packages. 

Recently, a cellular, structural biomaterial comprised of 15 to 25% tantalum (75 to 85% porous) has been developed. The average pore size is about 550 p,m, and the pores are fully interconnected. The porous tantalum is a bulk material (i.e., not a coating) and is fabricated via a proprietary chemical vapor infiltration process in which pure tantalum is uniformly precipitated onto a reticulated vitreous carbon skeleton. The porous tantalum possesses sufficient compressive strength for most physiological loads, and tantalum exhibits excellent biocompatibility [Black, 1994]. This porous tantalum can be mechanically attached or diffusion bonded to substrate materials such as Ti alloy. Current commercial applications included polyethylene-porous tantalum acetabular components for total hip joint replacement and repair of defects in the acetabulum. 

Examples AI2O3, low-temperature isotropic (LTI) carbon ultra LTI carbon vitreous carbon Z1O2 Tissue attachment Mechanical Bioactive ceramics... 

Sample preparation 600 p,L Vitreous humor -I- 3 mL 0.1 M NaCl -1- 50 p.L 4 p.g/mL desmethyldomipramine in water, mix for a few s, add to a C18 SepPak SPE cartridge attached to a 5 mL syringe, allow to flow throu (10-15 min). Wash with 1 mL 0.1 M NaCl, wash with 1 mL water, wash with 3 mL reagent by gravity. Elute with 3 mL MeOH and push air throu to remove as much as possible. Evaporate under vacuum at 37°, vortex with 50 xL mobile phase for 1 min, ii ject a 25 p,L aliquot. (Reagent was isopropanol n-heptane l M sulfuric acid 40 320 1.)... 

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