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171.
172.
Björn Alriksson Anders Sjöde Nils-Olof Nilvebrant Leif J. Jönsson 《Applied biochemistry and biotechnology》2006,130(1-3):599-611
Alkaline detoxification strongly improves the fermentability of dilute-acid hydrolysates in the production of bioethanol from
lignocellulose with Saccharomyces cerevisiae. New experiments were performed with NH4OH and NaOH to define optimal conditions for detoxification and make a comparison with Ca(OH)2 treatment feasible. As too harsh conditions lead to sugar degradation, the detoxification treatments were evaluated through
the balanced ethanol yield, which takes both the ethanol production and the loss of fermentable sugars into account. The optimization
treatments were performed as factorial experiments with 3-h duration and varying pH and temperature. Optimal conditions were
found roughly in an area around pH 9.0/60°C for NH4OH treatment and in a narrow area stretching from pH 9.0/80°C to pH 12.0/30°C for NaOH treatment. By optimizing treatment
with NH4OH, NaOH, and Ca(OH)2, it was possible to find conditions that resulted in a fermentability that was equal or better than that of a reference fermentation
of a synthetic sugar solution without inhibitors, regardless of the type of alkali used. The considerable difference in the
amount of precipitate generated after treatment with different types of alkali appears critical for industrial implementation. 相似文献
173.
The polarization asymmetries for thee + e ? scattering with polarized incoming and outgoing beams, which are proportional to the amplitudes? 5 describing one helicity flip and? 5 describing two helicity flips, have been calculated including their pure QED radiative corrections. These asymmetries are partly large and can be observed well at low energies. 相似文献
174.
Tadeus Nawka Lutz Christian Anders Mario Cebulla David Zurakowski 《Journal of voice》1997,11(4):422-428
Spectral analysis of vowels during connected speech can be performed using the spectral intensity distribution within critical bands corresponding to a natural scale on the basilar membrane. Normalization of the spectra provides the opportunity to make objective comparisons independent from the recording level. An increasing envelope peak between 3,150 and 3,700 Hz has been confirmed statistically for a combination of seven vowels in three groups of male speakers with hoarse, normal, and professional voices. Each vowel is also analyzed individually. The local energy maximum is called “the speaker's formant” and can be found in the region of the fourth formant. The steepness of the spectral slope (i.e. the rate of decline) becomes less pronounced when the sonority or the intensity of the voice increases. The speaker's formant is connected with the sonorous quality of the voice. It increases gradually and is approximately 10 dB higher in professional male voices than in normal male voices at neutral loudness (60 dB at 0.3 min). The peak intensity becomes stronger (30 dB above normal voices) when the overall speaking loudness is increased to 80 dB. Shouting increases the spectral energy of the adjacent critical bands but not the speaker's formant itself. 相似文献
175.
Stellan Jacobsson Anders Lundgren Joakim Johansson 《International Journal of Infrared and Millimeter Waves》1990,11(11):1251-1261
Computer generated Fourier transform phase holograms, known as kinoforms, have been synthesized, manufactured and their performance evaluated at a wavelength of 3 mm (100 GHz). The kinoforms were synthesized to give a prescribed far-field intensity distribution and manufactured by milling the computed kinoform surface relief into a Teflon plate, using a numerically controlled milling machine. The measured diffraction efficiencies exceed 50 percent. Millimeter-wave kinoforms can be used in various quasi-optical applications,e.g. distributing a local oscillator signal to an array of detector elements in heterodyne receivers. 相似文献
176.
177.
Anders Björn 《Potential Analysis》2007,27(4):381-387
We characterize regular boundary points for p-harmonic functions using weak barriers. We use this to obtain some consequences on boundary regularity. The results also
hold for -harmonic functions under the usual assumptions on , and for Cheeger p-harmonic functions in metric spaces.
相似文献
178.
In this paper we study tight lower bounds on the size of a maximum matching in a regular graph. For k ≥3, let G be a connected k-regular graph of order n and let α′(G) be the size of a maximum matching in G. We show that if k is even, then
, while if k is odd, then
. We show that both bounds are tight.
Research supported in part by the South African National Research Foundation and the University of KwaZulu-Natal. 相似文献
179.
Sandvik AW 《Physical review letters》2007,98(22):227202
Using ground-state projector quantum Monte Carlo simulations in the valence-bond basis, it is demonstrated that nonfrustrating four-spin interactions can destroy the Néel order of the two-dimensional S=1/2 Heisenberg antiferromagnet and drive it into a valence-bond solid (VBS) phase. Results for spin and dimer correlations are consistent with a single continuous transition, and all data exhibit finite-size scaling with a single set of exponents, z=1, nu=0.78+/-0.03, and eta=0.26+/-0.03. The unusually large eta and an emergent U(1) symmetry, detected using VBS order parameter histograms, provide strong evidence for a deconfined quantum critical point. 相似文献
180.
We study the three-dimensional XY model with a Zq anisotropic term. At temperatures T相似文献