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1.
Conidia of Aspergillus niger were immobilized in calcium alginate gel for the production of citric acid. First, the type of the preactivation medium,
together with the preactivation period, was investigated. It was found that A. niger requires a 2-d preactivation period at a 0.05 g/L NH4NO3 concentration. Second, preactivated cells were used to determine the effects of nitrogen concentration and the flow rate
of oxygen and air on the production of citric acid. Maximum citric acid production was attained with medium containing 0.01
g/L of NH4NO3. The rate of citric acid production in the nitrogenous medium was 33% higher when oxygen was used instead of air during the
production phase. This corresponds to an increase of 85% when compared to production when neither oxygen nor air was fed into
the system. In the nonnitrogenous medium citric acid concentration remained similar regardless of the use of air or oxygen.
However, in the nonnitrogenous production medium, citric acid production was not influenced considerably when oxygen was used
instead of air. The advantage of using immobilized cells is that production is achieved easily in the continuous system. Therefore,
citric acid production was also tested using a packed-bed bioreactor, and an increase in productivity by a factor of 22 was
achieved compared to the batch system. 相似文献
2.
We formulate a sufficient condition for the existence of a consistent price system (CPS), which is weaker than the conditional full support condition (CFS). We use the new condition to show the existence of CPSs for certain processes that fail to have the CFS property. In particular this condition gives sufficient conditions, under which a continuous function of a process with CFS admits a CPS, while the CFS property might be lost. 相似文献
3.
Erhan Bayraktar Arash Fahim 《Numerical Methods for Partial Differential Equations》2014,30(3):902-929
We present a stochastic numerical method for solving fully nonlinear free boundary problems of parabolic type and provide a rate of convergence under reasonable conditions on the nonlinearity. © 2013 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 30: 902–929, 2014 相似文献
4.
Sule Bayraktar 《School science and mathematics》2011,111(3):83-92
The main purpose of this study was to investigate the effectiveness of a primary teacher education program in improving science teaching efficacy beliefs (personal science teaching efficacy beliefs and outcome expectancy beliefs) of preservice primary school teachers. The study also investigated whether the program has an effect on student teachers' attitudes toward science. Data were collected by administering the “Science Teaching Efficacy Beliefs Instrument” and “Attitudes toward Science Scale” to 282 preservice primary teachers (147 freshmen, 135 seniors). Statistical techniques such as means and t‐test were used to analyze the data. Results of the study showed that the primary teacher education program has a medium positive effect on science teaching efficacy beliefs of the primary preservice teachers (t = 4.791, p = .000) and that there were no gender differences in terms of efficacy beliefs. Results also indicated that preservice primary teachers' attitudes toward science were moderately positive and differ by class level. Fourth‐year preservice teachers' attitudes toward science were found to be significantly more positive than the first years (t = 5.494, p = .000). There were no gender differences in attitudes toward science. 相似文献
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6.
Turgay Bayraktar 《Potential Analysis》2018,48(4):459-471
In this note, we obtain asymptotic expected number of real zeros for random polynomials of the form where \({a^{n}_{j}}\) are independent and identically distributed real random variables with bounded (2 + δ)th absolute moment and the deterministic numbers \({c^{n}_{j}}\) are normalizing constants for the monomials z j within a weighted L 2-space induced by a radial weight function satisfying suitable smoothness and growth conditions.
相似文献
$$f_{n}(z)=\sum\limits_{j=0}^{n}{a^{n}_{j}}{c^{n}_{j}}z^{j}$$
7.
Alemdar Bayraktar Abdurrahman ahin D. Mehmet
zcan Faruk Yildirim 《Applied Mathematical Modelling》2010,34(1):92-121
In the present paper, the numerical damage assessment of the masonry bell tower called “Haghia Sophia” in Trabzon, Turkey is performed by nonlinear 3D finite element modeling. The behavior of bell tower is determined under several different conditions: nonlinear static analysis containing dead and wind loads and nonlinear seismic analysis. In addition to, an assessment of the tower’s stability with respect to the tilt of the tower is carried out by means of a nonlinear analysis. In the nonlinear dynamic analysis, the east–west component of 1992 Erzincan earthquake is used. Cracking and crushing of the masonry have been taken into account, as well as the influence of material nonlinearity. The numerical analysis has given a valuable picture of possible damage evolution, providing useful hints for the prosecution of structural monitoring. The displacement and stress fields, as well as the distribution of cracking have been calculated and compared to the actual distribution of fractures in the tower. It is seen from the numerical results that there is a good agreement with present damages of the bell tower. 相似文献
8.
We investigate the continuity of expected exponential utility maximization with respect to perturbation of the Sharpe ratio of markets. By focusing only on continuity, we impose weaker regularity conditions than those found in the literature. Specifically, we require, in addition to the V-compactness hypothesis of Larsen and ?itkovi? (2007) [13], a local bmo hypothesis, a condition which is essentially implicit in the setting of [13]. For markets of the form S=M+∫λd〈M〉, these conditions are simultaneously implied by the existence of a uniform bound on the norm of λ⋅M in a suitable bmo space. 相似文献
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10.
Sandanaraj BS Bayraktar H Krishnamoorthy K Knapp MJ Thayumanavan S 《Langmuir : the ACS journal of surfaces and colloids》2007,23(7):3891-3897
An amphiphilic homopolymer scaffold has been used to bind to the protein, cytochrome c. This interaction is analyzed using cyclic voltammetry, native gel electrophoresis, UV-visible absorption, and circular dichroism spectroscopy. The polymer binds to cytochrome c with micromolar affinity and the association of polymer with cytochrome c leads to a structural change of the protein. This conformational change exposes the heme unit of the protein, which affords an opportunity to reversibly modulate its electron-transfer properties. We have also shown that the electrostatic binding of polymer to cytochrome c can be used to disrupt its interaction with its natural partner, cytochrome c peroxidase. 相似文献