Specialty silicas

Many other types of solid phase adsorbents, including those based on conventional and specialty materials like restricted access media (RAM), can increase analysis speed and improve assay performance. These types of materials, also known as internal reversed-phase packings, are especially useful for assaying target compounds in biological samples such as serum and plasma. They are chemically modified porous silicas that have hydrophilic external surfaces and restricted-access hydrophobic internal surfaces. The ratio of interior to external surface areas is large. Macromolecules such as proteins cannot enter the pores of the RAM (they are excluded from the hydrophobic internal surface) and they elute quickly through the column. However, the smaller analyte molecules that can enter the pores are retained via interactions with the hydrophobic bonded phase within... 

While silica plates are a typical place to start, separation of closely related structures can be achieved by switching to a specialty plate,... 

Silica, or silicon dioxide, occurs in various forms including chalcedony, which is a decorative material chert, which is used in abrasives flint, which is used in abrasives and ceramics jasper, which is used for decorative purposes quartz, which is a constituent of sand tripoli, which is found in scouring powders, polishers, and fillers cristobalite, which is used in high temperature casting and specialty ceramics diatomaceous earth, which is used in filtration processes and as a filler and finally, silica gel, which is used in dehydrating and drying. Note, however, that the material of concern is silica, and not silicates, which are relatively harmless derivatives of silica, nor silicones, synthetic materials used especially as lubricants. Neither silicates nor silicones cause proliferative conditions. 

Specialty Chemicals Coatings Additives Plastics Acetate Cable Rare Earths Silicas Fine Chemicals Sulfuric Acid Services... 

Release formulas for cakes, cookies, and other difficult specialty products often include 5-15% lecithin, 1-10% particulates (flour, silica, etc.), and various types of oils (mineral, vegetable, etc.). 

High Alumina and Insulating Brick, Silica Brick, and Specialty Brick and Block These special composition brick and block are employed for specific applications as outlined below ... 

Thermal Expansion and Thermal Shock Resistance In many situations it is difficult to directly substitute silica brick for red shale or fireclay. Changes in design might be needed to avoid subjecting the silica brick to destructive tensile or shear stresses during operation because of expansion differences. The thermal expansion of the specialty type silica product (Type 2) is much less than that of acid brick. The vitreous silica material which contains some crystalline Si02 (Type 1) has a thermal expansion that closely matches that of acid brick at temperatures less than 800°F. Above that temperature, the expansion is much less. 

As a whole, the thermal shock resistance of high silica materials is far superior to that of acid brick, especially the specialty product (Type 2). Some-... 

Silicone oils can be converted into pastes by incorporating large quantities of highly dispersed silicas or calcium or lithium soaps. These products are utilized as sealants and specialty greases. 

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