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Protein production with the recombinant yeast Saccharomyces cerevisiae in fed-batch culture is investigated in this work using beta-galactosidase as a model protein. Segregational instability was negligible during the observed culture periods. The final volumetric productivity, as determined by both cell concentration and gene expression, was strongly affected by the time course of the glucose levels in the bioreactor. It was found that an average glucose feed rate of 1.31 g glucose h-1 resulted in both the maximum beta-galactosidase production rate of 831-950 units ml-1 h-1 and the maximum cell production rate of 0.520-0.524 mg ml-1 h-1. 相似文献
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Rafiza Abdul Razak Mohd Mustafa Al Bakri Abdullah Kamarudin Hussin Khairul Nizar Ismail Djwantoro Hardjito Zarina Yahya 《International journal of molecular sciences》2015,16(5):11629-11647
This paper presents the mechanical function and characterization of an artificial lightweight geopolymer aggregate (ALGA) using LUSI (Sidoarjo mud) and alkaline activator as source materials. LUSI stands for LU-Lumpur and SI-Sidoarjo, meaning mud from Sidoarjo which erupted near the Banjarpanji-1 exploration well in Sidoarjo, East Java, Indonesia on 27 May 2006. The effect of NaOH molarity, LUSI mud/Alkaline activator (LM/AA) ratio, and Na2SiO3/NaOH ratio to the ALGA are investigated at a sintering temperature of 950 °C. The results show that the optimum NaOH molarity found in this study is 12 M due to the highest strength (lowest AIV value) of 15.79% with lower water absorption and specific gravity. The optimum LUSI mud/Alkaline activator (LM/AA) ratio of 1.7 and the Na2SiO3/NaOH ratio of 0.4 gives the highest strength with AIV value of 15.42% with specific gravity of 1.10 g/cm3 and water absorption of 4.7%. The major synthesized crystalline phases were identified as sodalite, quartz and albite. Scanning Electron Microscope (SEM) image showed more complete geopolymer matrix which contributes to highest strength of ALGA produced. 相似文献
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D. M. J. Sumajouw D. Hardjito S. E. Wallah B. V. Rangan 《Journal of Materials Science》2007,42(9):3124-3130
The objectives of this paper are to present the results of experimental study and analysis on the behaviour and the strength
of reinforced geopolymer concrete slender columns. The experimental work involved testing of twelve columns under axial load
and uniaxial bending in single curvature mode. The compressive strength of concrete for the first group of six columns was
about 40 MPa, whereas concrete with a compressive strength of about 60 MPa was used in the other six columns. The other variables
of the test program were longitudinal reinforcement ratio and load eccentricity. The test results gathered included the load
carrying capacity, the load-deflection characteristics, and the failure modes of the columns. The analytical work involved
the calculation of ultimate strength of test columns using the methods currently available in the literature. A simplified
stability analysis is used to calculate the strength of columns. In addition, the design provisions contained in the Australian
Standard AS3600 and the American Concrete Institute Building Code ACI318-02 are used to calculate the strength of geopolymer
concrete columns. This paper demonstrates that the design provisions contained in the current standards and codes can be used
to design reinforced fly ash-based geopolymer concrete columns. 相似文献
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