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11.
Aydin Berenjian Raja Mahanama Andrea Talbot Hubert Regtop John Kavanagh Fariba Dehghani 《Applied biochemistry and biotechnology》2014,172(3):1347-1357
A nutritional food rich in menaquinone-7 has a potential in preventing osteoporosis and cardiovascular diseases. The static fermentation of Bacillus subtilis natto is widely regarded as an optimum process for menaquinone-7 production. The major issues for the bulk production of menaquinone-7 are the low fermentation yield, biofilm formation and the use of organic solvents for the vitamin extraction. In this study, we demonstrate that the dynamic fermentation involving high stirring and aeration rates enhances the yield of fermentation process significantly compared to static system. The menaquinone-7 concentration of 226 mg/L was produced at 1,000 rpm, 5 vvm, 40 °C after 5 days of fermentation. This concentration is 70-fold higher than commercially available food products such as natto. Additionally, it was found that more than 80 % of menaquinone-7 was recovered in situ in the vegetable oil that was gradually added to the system as an anti-foaming agent. The intensification process developed in this study has a capacity to produce an oil rich in menaquinone-7 in one step and eliminate the use of organic solvents for recovery of this compound. This oil can, therefore, be used for the preparation of broad range of supplementary and dietary food products rich in menaquinone-7 to reduce the risk of osteoporotic fractures and cardiovascular diseases. 相似文献
12.
A set A {1,2,...,n} is said to be k-separated if, when consideredon the circle, any two elements of A are separated by a gapof size at least k. A conjecture due to Holroyd and Johnson that an analogue ofthe ErdsKoRado theorem holds for k-separated setsis proved. In particular, the result holds for the vertex-criticalsubgraph of the Kneser graph identified by Schrijver, the collectionof separated sets. A version of the ErdsKoRadotheorem for weighted k-separated sets is also given. 相似文献
13.
We apply kinetic theory and numerical simulation to the study of the fluctuation theorem for the work performed by an asymmetric piston immersed in a bath of gas particles. The symmetry function in the Brownian limit is predicted using a Langevin approach and is shown to be consistent with the numerical simulations. 相似文献
14.
Linear elastic surface waves are nondispersive. All wavelengths travel at the Rayleigh wave speed c
R. This absence of frequency dispersion means that nonlinear waves of permanent form cannot be determined as a small perturbation from a sinusoidal wavetrain. By representing the general Rayleigh wave of the linear theory in terms of a pair of conjugate harmonic functions, waves which propagate without distortion are characterized as those having surface elevation profiles which satisfy a certain nonlinear functional equation. In the small-strain limit, this reduces to a quadratic functional equation. Methods for the analysis of this equation are presented for both periodic and nonperiodic waveforms. For periodic waveforms, the infinite system of quadratic equations for the Fourier coefficients of the profile is solved numerically in the case of a certain harmonic elastic material. Two distinct families of profiles having phase speed differing from the linearized Rayleigh wave speed are found. Additionally, two families of exceptional waveforms are found, describing profiles which travel at the Rayleigh wave speed. 相似文献
15.
Th. W. Richards Ch. F. Mc. Caffrey H. Bisbee und H. P. Talbot 《Fresenius' Journal of Analytical Chemistry》1902,41(1):50-52
Ohne Zusammenfassung 相似文献
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The influence of spatial resolution, digitization noise, the number of records used for averaging, and the method of analysis on the determination of the fractal parameters of a high Damköhler number, methane/air, premixed, turbulent stagnation-point flame are investigated in this paper. The flow exit velocity was 5 m/s and the turbulent Reynolds number was 70 based on a integral scale of 3 mm and a turbulent intensity of 7%. The light source was a copper vapor laser which delivered 20 nsecs, 5 mJ pulses at 4 kHz and the tomographic cross-sections of the flame were recorded by a high speed movie camera. The spatial resolution of the images is 155 × 121 m/pixel with a field of view of 50 × 65 mm. The stepping caliper technique for obtaining the fractal parameters is found to give the clearest indication of the cutoffs and the effects of noise. It is necessary to ensemble average the results from more than 25 statistically independent images to reduce sufficiently the scatter in the fractal parameters. The effects of reduced spatial resolution on fractal plots are estimated by artificial degradation of the resolution of the digitized flame boundaries. The effect of pixel resolution, an apparent increase in flame length below the inner scale rolloff, appears in the fractal plots when the measurent scale is less than approximately twice the pixel resolution. Although a clearer determination of fractal parameters is obtained by local averaging of the flame boundaries which removes digitization noise, at low spatial resolution this technique can reduce the fractal dimension. The degree of fractal isotropy of the flame surface can have a significant effect on the estimation of the flame surface area and hence burning rate from two-dimensional images. To estimate this isotropy a determination of the outer cutoff is required and three-dimensional measurements are probably also necessary. 相似文献
18.
Brown PS Berson A Talbot EL Wood TJ Schofield WC Bain CD Badyal JP 《Langmuir : the ACS journal of surfaces and colloids》2011,27(22):13897-13903
The impact of picoliter-sized water droplets on superhydrophobic CF(4) plasma fluorinated polybutadiene surfaces is investigated with high-speed imaging. Variation of the surface topography by plasmachemical modification enables the dynamics of wetting to be precisely controlled. Final spreading ratios as low as 0.63 can be achieved. A comparison of the maximum spreading ratio and droplet oscillation frequencies to models described in the literature shows that both are found to be much lower than theoretically predicted. 相似文献
19.
John G. Kingston Richard F. Talbot 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1969,20(6):956-965
Résumé On donne ici la série complète des solutions pour les écoulements magnéto-hydrodynamiques permanents bidimensionnels d'un fluide incompressible, non-visqueux et nonconducteur de la chaleur ayant une conductivité électrique infinie lorsque le champ magnétique et le champ de vitesse sont partout orthogonaux. 相似文献
20.