The extraction of oil from canola (rapeseed) using hexane as a solvent can be described by a two stage washing/diffusion model. Oil which is at the surface of the seed as a result of pressing or cooking is removed rapidly at the beginning of the extraction process by simple washing by the solvent. This is followed by a slow extraction of the oil from the seed by a diffusional process. This latter process appears to be controlled by two mechanisms: slow, unhindered diffusion of oil held in the ruptured cells in the seed; and very slow, hindered diffusion of oil held within unruptured cells in the seed. To evaluate this model, rapeseed was extracted with commercial hexane in a simple bench scale batch extractor and the effects of variables such as particle thickness, temperature, cooking, degree of agitation, and solvent-to-seed ratio were studied.On peut dCcrire, au moyen d'un modele impliquant deux Ctapes de lavage/diffusion, I'extraction de I'huile de la graine de colza, pour I'hexane employe comme solvant. L'huile qui se trouve a la surface de la graine a la suite d'un pressurage ou d'une cuisson, est enlevCe rapidement au dCbut du procCdC d'extraction par simple effet de lavage par le solvant. 11 se produit ensuite une extraction lente de I'huile de la graine par un processus de diffusion. Ce dernier sernble contr6lC par deux mCcanismes, 5 savoir (a) une diffusion libre lente de I'huile retenue dans les cellules bristes de la graine et (b) une diffusion contrainte tres lente de I'huile retenue dans les cellules non brisCes de la graine. Pour Cvaluer le modele, on a extrait la graine de colza avec de I'hexane commercial dans un simple extracteur discontinu de laboratoire et I'on a CtudiC les effets de variables telles que I'epaisseur des particules, la tempLrature, la cuisson, le degrC d'agitation et la proportion solvant/grain. anola, containing 40% of more oil by weight, is grown

Summary Post operative surgical wound infection rates were determined for 452 cases of equine orthopaedic surgery performed at the Western College of Veterinary Medicine, Saskatoon, Saskatchewan, between January 1, 1981 and December 31, 1990. Only surgical procedures classified as clean or clean‐contaminated by the National Research Council were included in this study. The overall post operative infection rate was 10.0% (45 of 452). Clean surgeries (n=433) had an 8.1% infection rate while clean‐contaminated surgeries (n=19) had a 52.6% infection rate. Information collected from the medical records was used in univariate and multivariate logistic regression models to evaluate significant determinates of post operative infection. Significant determinates of post operative infection were: surgical classification, orthopaedic involvement, duration of surgery, administration of preoperative antibiotics and gender. Clean‐contaminated surgeries had an increased risk of infection compared to clean surgeries (odds ratio (OR)=24.3), procedures involving long bones had an increased risk of infection compared to procedures involving articular surfaces (OR =5.1), surgeries lasting 90 minutes or longer had an increased risk of infection compared to those less than 90 minutes (OR =3.6), administration of preoperative antibiotics was associated with an increased risk of infection (OR =4.6) and female patients were 2.6 times more likely to develop post operative infection than male patients.

The kinetics of crystalline cellulose and hemicellulose hydrolysis in corn stover were studied with a nonisothermal technique. Reactions were arrested at temperatures between 160 and 240 degrees C and product sugars were analyzed using a Bio-Rad HPX-85 liquid chromatographic column. A simple first-order series reaction model was used for both cellulose and hemicellulose hydrolysis reactions. Kinetic parameters were obtained for three different sulphuric acid concentrations (0.49, 0.92, and 1.47 wt %). Activation energies remained constant over this acid concentration range but the preexponential factors showed an increase with acid concentration. Relationships were obtained between the preexponential factors and acid concentrations. Cellulose hydrolysis and glucose degradation reactions were observed to be of higher order with respect to acid concentration in comparison with the previous studies with other raw materials.

Alkali treatment of corn stover improves the avaliability of cellulose and hemicellulose for enzymatic attack. Treatments were carried out for 1 to 60 min at temperatures and NaOH concentrations ranging from 100 to 150 degrees C and 0 to 2%, respectively. Solubilization of the stover and sugar production by enzymatic hydrolysis (Trichoderma viride cellulase) of the solid residue and the dissolved solids were used to measure the effect of caustic treatment. At 150 degrees C and 2% NaOH concentration, 65% of the original stover was dissolved after 5 min and 52% saccharificatin (g sugar/g stover) of the residue and dissolved solids by enzymatic hydrolysis was achieved compared to 20% for untreated corn stover.

Three a-amylase enzymes were used to hydrolyze wheat starch granules suspended in water below the gelatinization temperature. The rates of hydrolysis were determined at various temperatures, pH, enzyme and starch concentrations. Barley amylase was found to be the "best" enzyme when used at pH 4.5,45"C and starch and enzyme concentrations of 30 and 8 mg/mL respectively. It was found that under these conditions, 98% of the starch granules were hydrolyzed in 3 hours, the same amount of time used in the industrial cooking process of soluble starch. Starch particles were observed to be attacked at specific points on the surface and then hydrolyzed from the inside-out. Some granules were hydrolyzed at a very fast rate with a first order rate constant estimated to be 40 h-'; but most granules were hydrolyzed slowly according to the Michaelis-Menten model and the best fit parameters were found to depend on enzyme type, pH and temperature.On a utilise trois enzymes a-amylase pour hydrolyser des granules d'amidon de ble suspendus dans I'eau sous la temperature de gelatinisation.

The kinetics of cellulose and hemicellulose hydrolysis of wheat straw was studied using both isothermal and non‐isothermal techniques in a batch reactor. Reactions were carried out between 100 and 210°C and product sugars were analyzed using a Bio‐Rad HPX‐87P liquid chromatographic column. A simple first order series reaction model was used for both cellulose and hemicellulose hydrolysis reactions and kinetic parameters were obtained for the Arrhenius rate equations for three different sulphuric acid concentrations (0.5, 1.O and 1.5%). Activation energies remained constant with acid concentration but the pre‐exponential factors showed an increase with acid concentration. To minimize the amount of experimental data required and to achieve a unique solution to the kinetic parameters, the technique of combining isothermal and non‐isothermal reaction data was studied.

No abstract

No abstract