Controlled-pore glass particles

For the automated solid-phase synthesis of oligonucleotides, however, silica was found to be the support of choice [192-197]. Silica with large pore size (25-300 nm), so-called controlled pore glass (CPG), is generally used for this purpose. The main advantages of CPG, as compared with silica gel, are its more regular particle size and shape, and greater mechanical stability. 

Fig. 7. kf versus linear flow rate calculated for BSA adsorption to fluidized controlled pore glass after Rowe (A, Eq. 19, Ref. 74) and after Fan et al. ( , Eq. 20, Ref. 75). Physical data of adsorbent average particle diameter 200 pm, average particle density 1240 kg/m3, BSA diffusion coefficient in solution 7.3-10 11 m2/s, bed expansion calculated according to Richardson and Zaki, U, and n estimated according to Eqs. (3-5)... 

A dry packed column with porous material was used for the characterization according to size of the PVAc latex samples. The packing employed was CPG (Controlled Pore Glass), 2000 A, 200-400 mesh size. Deionized water with 0.8 gr/lit Aerosol O.T. (dioctyl sodium sulphosuccinate), 0.8 gr/lit sodium nitrate and 0.4 gr/lit sodium azide served as the carrier fluid under a constant flowrate. The sample loop volume was 10 pC A Beckman UV detector operating at 254 nm was connected at the column outlet to monitor particle size. A particle size-mean retention volume calibration curve was constructed from commercially available polystyrene standards. For reasons of comparison, the samples previously characterized by turbidity spectra were also characterized by SEC. A number of injections were repeated to check for the reproducibility of the method. 

The initial measurement with APS-treated capillaries produced distorted particle-mobility parabolas consistent with desorption onto particles near the wall. Subsequent measurements did not produce such an effect and thus indicated that a stable APS layer remained. It should also be noted that a hydrothermally stable sublayer of density 0.48 nm-2 was observed on controlled-pore glass by Fang (251-... 

The so-called medium performance AC supports can withstand higher pressures, and have particle sizes of 40 pm. Examples include hydrophylic polyacrylamides (pH 1-14, 100 psi), as well as the bonded-phase silica/controlled-pore glass supports (pH 2-8, >1000 psi). 

The first investigation of the influence of particle mass transfer on the reaction kinetics in a flow microcalorimeter, dealing with properties of urease immobilized on controlled pore glass, was published in 1985 [25]. More recently, the evaluation of microcalorimetric data in the case of particle-diffusion limitation was improved and simplified by introducing the principle of the differential bed [28,29]. 

Preparation of supported copper catalysts. Two different supports were used to prepare supported catalysts. Silica gel with specific surface area of 200 m /g, pore volume of 1.5 cm /g, and particle size of 0.02-0.20 mm was used without any further treatment. The controlled pore glass (CPG) support (particle size 0.045-0.10 mm) was prepared as described elsewhere [4,5]. CPG support with surface area of 33 m /g, pore size 75 nm, pore volume 0.59 cm /g was used. The catalysts were prepared by incipient wetness impregnation of the support with Cu(ll) nitrate in the presence of citric acid followed by drying in air at 230 °C. The dried samples were calcined at 500 °C for 5 hours followed by reduction in a hydrogen atmosphere at 300-400 °C. 

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