Fetal calf serum-free suspension culture of Chinese hamster ovary cells employing fish serum

The effects of heat treatment and concentration of fish serum (FS) on cell growth in a suspension culture of recombinant Chinese hamster ovary (CHO) 1-15₅₀₀ (ATCC CRL-9606) cells were investigated. An increase in FS concentration from 1% to 4% markedly increased cell density. On the other hand, heat treatment of FS showed nearly no effect on cell density.     

Classification of fermentation performance by multivariate analysis based on mean hypothesis testing

Multivariate analysis, such as principal component analysis and artificial autoassociative neural networks, is currently extensively applied to feature capturing, physiological state recognition, fault detection and bioprocess control. However, it is not clear which process variable should be selected as an important input for multivariate analysis to analyze physiological conditions and/or bioprocess performance a priori. An efficacious method to select more informative process variables from the repository of historical data is highly desired. In this study, we focused on a premodeling step. Mean hypothesis testing (MHT) was used to select appropriate variables for multivariate analysis. Fermentation data sets were classified into two classes "good" and "bad" according to the MHT results. The results showed that selecting discriminating process variables from the historical database by MHT enhanced the overall effectiveness of multivariate analysis prior to principal component analysis and artificial autoassociative neural network model creation.     

Finite element creep analysis of PCRVs and comparison with experimental results

In order to investigate the validity and application of a finite element creep analysis program developed for the design of PCRV, a creep test was carried out on a scale model of a PCRV and the results were compared with those from numerical analysis. Based on the rate of flow method, the creep strain of concrete is divided into two components: flow strain (irreversible creep) which is assumed to be a linear function in the logarithmic scale of t, and delayed elastic strain (reversible creep) which is expressed as an exponential function of flow strain. The analysis program is based on the finite element method in which triangular constant strain elements for solids of revolution are used and the time-step analysis function, in the form of the initial strain method, is provided. In the analysis of the PCRV model constant creep Poisson's ratios of 0.17, 0.3 and 0.5 are assumed for the purpose of comparison. The constitutive model based on the rate of flow method satisfactorily modelled the uniaxial creep behaviour of test cylinders and the computed strains simulated the characteristics of the strain histories of the PCRV model fairly well in the qualitative sense.     

Characterization of microvoids in mulberry and tussah silk fibers using stannic acid treatment

To investigate the volume, size, and number of microvoids in mulberry and tussah silk fibers, stannic acid gel was used as a contrasting medium to the small-angle X-ray scattering (SAXS). The influence of the stannic acid treatment on the structure of silk fibers was first investigated by using the wide-angle X-ray diffraction prior to characterization of the microvoids. The changes in crystallite size and degree of orientation with increasing stannic acid gel fraction in fibers are investigated, and it was found that the stannic acid treatment does not cause serious changes in crystallite size and degree of orientation. The changes in crystallinity indices were observed when the volume fractions of stannic acid gel in the fibers exceeded about 10%. Thus, it was confirmed that the structure of silk fibers was retained in the region of the stannic acid gel fraction less than 10%. SAXS measurements revealed that the number and the fraction of the microvoids are larger, while the sizes of the microvoids are smaller, for the mulberry silk fibers compared with the tussah silk fibers. The fraction macrovoids, however, is considered to be larger for the tussah silk fibers. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 363–367, 1999     

Characteristics of electric power transmission on high-frequencyinverter having distributed constant line at load side

An induction heating system aimed at improving the characteristics of high-frequency power supplied from the high-frequency, inverter to the parallel resonant load circuit is proposed, and its transmission efficiency is studied. In this system, high-frequency power can be supplied by lowering the effect of the inductance component accompanied by wiring between the inverter circuit and the resonant load circuit. Impedance matching between the inverter and the resonant circuit and high-efficiency power transmission from the inverter to the load circuit are possible. If a flexible coaxial cable is used as the distributed constant line, it is easy to cope with the case in which comparative distance exists between the inverter part and the heating part or the case in which the heating part is moved     

X-ray measurements and the structure of polyacrylonitrile- and pitch-based carbon fibres

X-ray measurements were carried out on polyacrylonitrile- and pitch-based carbon fibres. The crystallites, disordered regions and microvoids in these carbon fibres were evaluated quantitatively by applying the methods previously proposed by the present authors. The structural parameters evaluated are the 1 1 plane spacing of the carbon layer, the average, standard deviation and asymmetry of the distribution of interlayer spacing, the stacking regularity parallel to the layer plane, the layer extents parallel and perpendicular to the fibre axis, the stacking height, the crystallite orientation, the volume fractions of crystallites, disordered regions and microvoids, the variation of the electron density in a microvoid, and the size parameters of the void cross-section perpendicular to the fibre axis, such as the area, radius of gyration, chord length and thickness. The mutual relationships of these structural parameters are presented, and parameters sensitive to the nature of the starting materials are pointed out.     

Bubble column fermenter modeling: A comparison,for pressure effects

Two models which describe the oxygen transfer, oxygen uptake, and axial mixing in a bubble column fermenter are described. Model I includes no pressure effects and can be solved analytically. Model II incorporates the influence of hydrostatic pressure on oxygen solubility and gas expansion and must be solved numerically. The liquid phase oxygen concentration profiles as obtained from both models are compared to ascertain for what parametric conditions and for what maximum column height Model I is valid. The results show that for many situations Model I can approximate the oxygen profiles in a 10 m column within 20%. As the transfer and uptake rates increase the deviation of Model I can reach 80% for a 10 m column.