Volume volume 2 no.1 1992

ABSTRACT: Saccharomyces cerevisiae var. ellipsoideus and Kluyveromyces fragilis produced 59.8 and 69.0 g/l ethanol respectively when grown in cocoa waste at 30°C by continuous fermentation. Maximum ethanol production by the species was achieved at cell biomass concentrations of 2.7 g/l and 2.9 g/l respectively. S.cerevisiae (wild strain) grown under similar conditions in pineapple juice produced 70.0 g/l of ethanol at a cell biomass concentration of 3.9 g/l AUTHOR: Othman Abdul Samah, Abdul Rashid Abdul Rahman and Mohd Ismail Abdul Karim KEYWORDS : Micro-organisms, utilization, agrowastes, biofuel production.

ABSTRACT: A quater car model is used to study the effect of 'ON/OFF' control strategies on ride dynamics. The strategies are applied to the damper in order to drive a semi-active suspension system. Comparisons are made between the passive and semi-active system. Maximum relative displacement and maximum jerk experienced by the sprung mass are recorded during the simulations. AUTHOR: Mohd. Jailani Mohd. Nor KEYWORDS : Semi-active, suspension, jerk, damping, displacement, velocity, acceleration, automobile, comfort.

ABSTRACT: Aspergillus terreus IMI 282743 was found to produce high activities of extracellular cellulases when grown in 20 litre and 100 litre fermentors. The activities are comparable to that reported by the commercially available Trichoderma reesei, wild type strain. The organism showed tendency for pellet-type growth which is favourable for air-lift fermentor operation. Maximum activities of exoglucanase, 0.69 U/ml; endoglucanase, 5.70 U/ml; and ß-glucosidase, 0.80 U ml:1; were obtained after 5 days of growth in 0.5% cellulose at 33°C with pH controlled at 4.5. The corresponding productivities for the enzymes were 6.31, 66. 70 and 8.40 U/l/h. A high growth yield of the organism was observed at 0.176 g protein per g cellulose. At a cellulose concentration of 1.0%, ß-glucosidase activity increased by 400% while the exo- and endoglucanase activities remained relatively unchanged. The enzyme composition profile can be modified by changing the substrate concentration, pH and temperature of fermentation. AUTHOR: Zainal Abidin Mohd Yusof KEYWORDS : Aspergil/us terreus, extracellular cellulase, high ß-glucosidase, enzyme composition profile.

ABSTRACT: The silica source for the synthesis of zeolite NaY was extracted from rice husk ash in the form of waterglass. The different degrees and techniques of neutralization of the waterglass, followed by various post treatments of the precipitated hydrogel, affected the zeolite formation. Failure of the zeolitization process was attributed to the state of the silica particles and the high water content in the hydrogels. Zeolite NaY was successfully produced from the precipitated silica which was dried and used in its powdered form, and also from "well-drained" hydrogels. The time taken for the synthesis was also investigated. Characterization and quantitative analyses were determined solely by the X-ray diffraction technique. Rice husk ash was found to be a suitable silica source. AUTHOR: S.S. Chen and A.K. Yeoh KEYWORDS: Zeolite NaY, faujasite, silica, rice husk ash (AHA), waterglass, sodium silicate, hydrothermal synthesis, gel formation, XRD.