3,769 research outputs found
INDIRECT ESTIMATION OF CELL MASS AND SUBSTRATE CONCENTRATION USING A COMPUTER-COUPLED MASS-SPECTROMETER
No full textOn-line estimation of cell mass and substrate concentration based on exhaust gas analysis was developed. The O-2, CO2, H2O, and N-2 contents at the inlet and outlet of fermenter, analyzed by a computer-coupled quadrupole mass spectrometer, were used to calculate the oxygen uptake rate and carbon dioxide evolution rate, and these rates were further used to evaluate cell mass and substrate concentration in a recombinant Escherichia coli fermentation. Cell mass, glucose concentration, specific growth rate, and specific consumption rate of glucose were well estimated by this method; the oxygen uptake rate gave more accurate estimates for these state variables than did the carbon dioxide evolution rate
Quantitative Analysis of Metabolic Activities During Cloned Gene Expression using Mass Spectromerer
No full textEFFECT OF STRESS FREQUENCY ON THE CYCLIC CREEP-BEHAVIOR OF ZIRCALOY-4 IN THE DYNAMIC STRAIN AGING TEMPERATURE-RANGE
No full textThe analytic function expansion nodal method refined with transverse gradient basis functions and interface flux moments
No full textA refinement of the analytic function expansion nodal (AFEN) method is described. By increasing the number of flux expansion terms in the way that the original basic functions are combined with the transverse-direction linear functions, the refined AFEN method can describe the flux shape in the nodes more accurately, since the added flux expansion terms still satisfy the diffusion equation. The additional nodal unknowns introduced are the interface flux moments,, and the additional constraints required are provided by the continuity conditions of the interface flux moments and the interface current moments. Also presented is an algebraically exact method for removing the numerical singularity that can occur in any analytic nodal method when the core contains nearly no-net-leakage nodes. The refined AFEN method was tested on the Organization for Economic Cooperation and Development (OECD)-L336 mixed-oxide benchmark problem in rectangular geometry, and the VVER-440 benchmark problem and a nearly no-net-leakage node embedded core problem, both in hexagonal geometry. The results show that the method improves not only the accuracy in predicting the flux distribution but also the computing time, and that it can replace the corner-point fluxes with the interface flux moments without accuracy degradation, unless the problem consists of strongly dissimilar nodes. The possibility of excluding the corner-point fluxes increases the flexibility in implementing this method into the existing codes that do have the corner-point fluxes scheme and may make it fit better for the nonlinear scheme based on two-node problems
FORMATION OF PHOSPHIDES IN P-DOPED 304L STAINLESS-STEEL
No full textThe precipitation of phosphide and the orientation relationship with the austenitic matrix in P-doped 304L stainless steel have been studied in detail using transmission electron microscopy and computer-simulated stereographic projection. The M3P phosphide was identified in aged samples and confirmed by computer simulation of selected area diffraction patterns. The needle-shaped phosphide is randomly distributed in the austenitic matrix, and grows into thin laths on <001>M austenite planes
APPLICATION OF NEURAL NETWORKS TO MULTIPLE ALARM PROCESSING AND DIAGNOSIS IN NUCLEAR-POWER-PLANTS
No full textWe present the feasibility study of multiple alarm processing and diagnosis using neural networks. The back-propagation network (BPN) algorithm is applied to the training of multiple alarm patterns for the identification of faults in a reactor coolant pump (RCP) system. The general mapping capability of the neural network enables to identify a fault easily. A number of case studies are performed with emphasis on the applicability of the neural network to the pattern recognition of multiple alarms. Based on the case studies, the neural network can identify the cause of multiple alarms well, although untrained, incomplete/sensor-failed or time-varying alarm symptoms are given. Also, multiple faults are easily identified with a given alarm pattern
Optimization of feeding strategy for overproduction of human lipocortin-I in Saccharomyces cerevisiae controlled by the GAL10 promoter
No full textFed-batch fermentation was conducted to overproduce human lipocortin-1 (LC1) in recombinant Saccharomyces cerevisiae controlled by the GAL10 promoter. To optimize the feeding strategy, various fed-batch culture modes were performed with concentrated feed media containing carbon mixtures of galactose (Gal) and glucose (Glu) at three different concentration ratios (Gal:Glu ratios): 9:1, 1:1, 1:9. The cell growth, expression level of LC1, and the plasmid stability were investigated under these fed-batch culture modes, While both glucose and galactose were being fed to the fermenter, the glucose concentration in the culture broth was kept below 1 g/l for efficient gene expression. High cell concentrations of greater than 100 g dry cell weight/l mere achieved with these fed-batch culture modes. A significant amount of intact LC1 was found to be secreted into the culture medium, but proteolytically cleaved products (des1-26-LC1) were also observed in the culture medium. The fed-batch fermentation with the feed medium at a Gal: Glu ratio of 1:1 resulted in the highest LC1 total (intact LC1+des1-26-LC1) concentration of 500 mg/l, which corresponded to 1.73- and 1.83-fold increases over that produced with the media at Gal: Glu ratios of 1:9 and 9:1, respectively
- …
