排序方式: 共有31条查询结果,搜索用时 62 毫秒
21.
22.
Nonlinear Dynamics - This paper deals with the tracking approach of a self-generated stable limit cycle for an underactuated mechanical system: The inertia wheel inverted pendulum (IWIP). Such... 相似文献
23.
Maalej I Belhaj I Masmoudi NF Belghith H 《Applied biochemistry and biotechnology》2009,158(1):200-212
A thermostable xylanase from a newly isolated thermophilic fungus Talaromyces thermophilus was purified and characterized. The enzyme was purified to homogeneity by ammonium sulfate precipitation, diethylaminoethyl
cellulose anion exchange chromatography, P-100 gel filtration, and Mono Q chromatography with a 23-fold increase in specific
activity and 17.5% recovery. The molecular weight of the xylanase was estimated to be 25kDa by sodium dodecyl sulfate–polyacrylamide
gel electrophoresis and gel filtration. The enzyme was highly active over a wide range of pH from 4.0 to 10.0. The relative
activities at pH5.0, 9.0, and 10.0 were about 80%, 85.0%, and 60% of that at pH7.5, respectively. The optimum temperature
of the purified enzyme was 75°C. The enzyme showed high thermal stability at 50°C (7days) and the half-life of the xylanase
at 100°C was 60min. The enzyme was free from cellulase activity. K
m and V
max values at 50°C of the purified enzyme for birchwood xylan were 22.51mg/ml and 1.235μmol min−1 mg−1, respectively. The enzyme was activated by Ag+, Co2+, and Cu2+; on the other hand, Hg2+, Ba2+, and Mn2+ inhibited the enzyme. The present study is among the first works to examine and describe a secreted, cellulase-free, and
highly thermostable xylanase from the T. thermophilus fungus whose application as a pre-bleaching aid is of apparent importance for pulp and paper industries. 相似文献
24.
25.
26.
When grown on wheat bran as the only carbon source, the filamentous fungus Talaromyces thermophilus produces large amounts of beta-xylosidase activity. The presence of glucose drastically decreases the beta-xylosidase production level. The beta-xylosidase of T. thermophilus was purified by ammonium sulfate precipitation, DEAE-cellulose chromatography, and gel filtration (high-performance liquid chromatography). The molecular mass of the enzyme was estimated to be 97 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis and gel filtration. The enzyme activity was optimum at 50 degrees C and pH 7. The apparent Michaelis constant K(m) of the beta-xylosidase was 2.37 mM for p-nitrophenyl-beta-D-xylopyranoside, with a V(max) of 0.049 micromol min(-1) per milligram protein. Enzyme activity was inhibited by Cu(2+), Hg(2+), and Zn(2+) and activated by Ca(2+), Mn(2+), and Co(+) at a concentration of 5 mM. At high xylose concentration, this enzyme catalyses the condensation reaction leading to xylobiose production. 相似文献
27.
Elsharkawya Safya Hammad Sherin El-hallaga Ibrahim 《Journal of Solid State Electrochemistry》2022,26(6):1501-1517
Journal of Solid State Electrochemistry - Nanostructured Ni films were synthesized from two distinct baths and were assessed as electrocatalysts for hydrogen evolution reaction (HER) and oxygen... 相似文献
28.
Nonlinear Dynamics - The compass-gait biped robot is a two-DoF legged mechanical system that has been known by its passive dynamic walking. This kind of passive biped robot is modeled by an... 相似文献
29.
30.
Hassène Gritli Nahla Khraief Safya Belghith 《Communications in Nonlinear Science & Numerical Simulation》2012,17(11):4356-4372
This paper presents a study of the passive dynamic walking of a compass-gait biped robot as it goes down an inclined plane. This biped robot is a two-degrees-of-freedom mechanical system modeled by an impulsive hybrid nonlinear dynamics with unilateral constraints. It is well-known to possess periodic as well as chaotic gaits and to possess only one stable gait for a given set of parameters. The main contribution of this paper is the finding of a window in the parameters space of the compass-gait model where there is multistability. Using constraints of a grazing bifurcation on the basis of a shooting method and the Davidchack–Lai scheme, we show that, depending on initial conditions, new passive walking patterns can be observed besides those already known. Through bifurcation diagrams and Floquet multipliers, we show that a pair of stable and unstable period-three gait patterns is generated through a cyclic-fold bifurcation. We show also that the stable period-three orbit generates a route to chaos. 相似文献