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141.
142.
Isci A Himmelsbach JN Pometto AL Raman DR Anex RP 《Applied biochemistry and biotechnology》2008,144(1):69-77
Simultaneous saccharification and fermentation (SSF) of switchgrass was performed following aqueous ammonia pretreatment.
Switchgrass was soaked in aqueous ammonium hydroxide (30%) with different liquid–solid ratios (5 and 10 ml/g) for either 5
or 10 days. The pretreatment was carried out at atmospheric conditions without agitation. A 40–50% delignification (Klason
lignin basis) was achieved, whereas cellulose content remained unchanged and hemicellulose content decreased by approximately
50%. The Sacccharomyces cerevisiae (D5A)-mediated SSF of ammonia-treated switchgrass was investigated at two glucan loadings (3 and 6%) and three enzyme loadings
(26, 38.5, and 77 FPU/g cellulose), using Spezyme CP. The percentage of maximum theoretical ethanol yield achieved was 72.
Liquid–solid ratio and steeping time affected lignin removal slightly, but did not cause a significant change in overall ethanol
conversion yields at sufficiently high enzyme loadings. These results suggest that ammonia steeping may be an effective method
of pretreatment for lignocellulosic feedstocks. 相似文献
143.
Senem Demir Cigdem
zen Meltem Ceylan‐Ünlüsoy Mehmet
ztürk Oya Bozda‐Dündar 《Journal of heterocyclic chemistry》2019,56(4):1341-1351
Medicinal plant extracts have been used for medical purposes throughout human history. In this study, khellin, having furochromone structure, which is obtained from a well‐known traditional medicinal plant, was selected. A series of furochromonyl compounds ( K1 – K14 ) were synthesized for their anticancer activities. Furochromonyl compounds ( K1 – K14 ) were synthesized by Knoevenagel reaction of substituted 2,4‐thiazolidinediones ( Ia – j )/rhodanines ( Ik – n ) with khellin‐2‐carboxaldehyde ( V ), and their cytotoxicity was investigated in 22 cancer cell lines, which were originated from tissues such as the liver, breast, colon, and cervix. As the first step, two hepatocellular carcinoma cell lines Huh7 and PLC/PRF/5 (Alexander cells) were treated with 10 μM of each compound for 72 h, and then sulforhodamine B assay was performed to analyze their anti‐growth activities. Ethyl 2‐(5‐((4,9‐dimethoxy‐5‐oxo‐5H‐furo[3,2‐g]chromen‐7‐yl)methylene)‐4‐oxo‐2‐thioxothiazolidin‐3‐yl)acetate ( K11 ) was found as the most cytotoxic compound of primary screening. Afterwards, 12 hepatocellular carcinoma, seven breast cancer, two colon cancer, and a cervical cancer cell lines were selected to test K11 for 72 h at multiple concentrations to determine 50% effective doses. Results showed that the 14 cell lines were affected by K11 quantities lower than 10 μM. The structure of K11 , which is particularly effective on breast cancers, can be used to slow down the progression of tumors. Furthermore, the discovery of more effective compounds can be carried out on the basis of this structure. 相似文献
144.
When a Lur’e-type system which cannot exhibit chaotic behavior and whose linear part is of a second order, is tried to be controlled by an integer order controller, chaotic behaviors can occur depending on the controller parameters. In this article, in the case when a fractional order PI α is chosen, provided that the controller parameters remain unchanged, the effect of the integral order α for the interval 0<α<1 has been investigated. It has been shown through two examples that depending on the integral order α, the fractional order PI α controller prevents the chaotic behavior by releasing the extra dynamics that was loaded onto the system by the integer order PI controller. To determine at which α parameter the system exhibits chaotic behavior, the frequency domain approach based chaos prediction method—Genesio–Tesi conjecture—has been used. 相似文献
145.
The vibration of orthotropic rectangular plates having viscoelastic point supports symmetrically located on its diagonals
is analyzed. The plate is under the effect of a sinusoidally varying force at its center. The Lagrange equations are used
in the solution process. To apply the Lagrange equations, the trial function denoting the deflection of the plate is expressed
in polynomial form. By using the Lagrange equations, the problem is reduced to the solution of a system of algebraic equations.
The influence of the mechanical properties, the damping of the supports and the locations of point supports on the steady-state
response of the viscoelastically point-supported rectangular plates is investigated numerically for the concentrated load
at center for various values of the mechanical properties characterizing the anisotropy of the plate material and for various
values of damping and location of the supports for a certain stiffness value of the supports. The results are given for the
considered frequency range of the external force. Convergence studies are made. The validity of the obtained results is demonstrated
by comparing them with other solutions based on the Kirchhoff–Love plate theory. 相似文献
146.
147.
Chicken, duck, and quail egg shells were γ-irradiated and investigated by electron paramagnetic resonance (EPR) at ambient
temperature and at 113 K. The EPR-active species after γ-irradiation were attributed to the ĊO3−, ĊO33−, and ĊO2− radicals at ambient temperature and at 113 K. Furthermore, when the samples were stored in an oven at 423 K for about 1 h
new EPR signals appeared at ambient temperature in addition to the above ones and these signals were attributed to the (CH3)2Ċ-R radical. These signals appear also at 113 K, but they are broadened likely due to the freezing of some of their motions.
Any significant difference between the egg shells of poultry and those of village-grown chickens could not be observed in
EPR spectra. The duck and quail egg shells exhibit the same signals and therefore indicate the inducement of the same radicals.
The spectroscopic splitting and the hyperfine interaction values were found to be consistent with the literature data. 相似文献
148.
Alinur Büyükaksoy Ahmet Demir 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2005,46(1):694-717
A rigorous solution is presented for the problem of diffraction of plane harmonic sound waves by a cavity formed by a terminated rigid cylindrical waveguide of finite length whose interior surface is lined by an acoustically absorbent material. The solution is obtained by a modification of the Wiener-Hopf technique and involve an infinite series of unknowns, which are determined from an infinite system of linear algebraic equations. Numerical solution of this system is obtained for various values of the parameters of the problem and their effects on the diffraction phenomenon are shown graphically. 相似文献
149.
A variety of Hantzsch ester 1,4‐dihydropyridines are efficiently oxidized to their corresponding pyridine compounds with iodine under normal conditions and ultrasound irradiation. The reactions were carried out in refluxing CH3CN. 相似文献
150.
A highly effective, easy to handle and environmentally benign process for palladium‐mediated Suzuki cross‐coupling is developed. The in situ prepared three‐component system Pd(OAc)2–1,3‐bis(alkyl)imidazolinium chlorides (2a–f) and Cs2CO3 catalyses quantitatively the Suzuki cross‐coupling of deactivated aryl chlorides. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献