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41.
42.
A novel thermophilic xylanase-producing fungus, Chaetomium sp. CQ31 produced 131 U ml−1 of xylanase when grown on a medium containing corncob (3.5%, w/v) at 37 °C for 6 days. A low molecular xylanase was purified 6.5-fold to homogeneity with a recovery yield of 17.5%. Its molecular mass was estimated to be 25.1 kDa by SDS–PAGE. The xylanase had an optimum pH of 7.5, and its optimal temperature was 65 °C. Apparent Km values of the xylanase for birchwood, beechwood and oat-spelt xylan were 1.3, 0.86 and 4.4 mg/ml, respectively. The influence of this xylanase on the quality of Chinese steamed bread (CSB) was further studied. Addition of xylanase in the range 2.5–5.0 ppm caused a 20–24.5% increase in specific volume over the control and remarkable decrease (8.9–24.2%) in firmness was also noticed. This is the first report on the purification, characterisation and application of a xylanase from Chaetomium sp. CQ31. 相似文献
43.
S. C. Sharma M. Krishna H. N. Narasimha Murthy 《Journal of Materials Engineering and Performance》2006,15(3):306-310
The objective of this paper is to study the influence of drilling velocity, feed rate, and flank length on the delamination
of polyurethane foam sandwich structures. A Taguchi-based design of experiments was used to assess the importance of the drilling
parameters, and scanning electron microscopy (SEM) was used to assess the damage from drilling. The drilling of sandwich structures
results in significant damage caused by delamination and surface roughness around the drilled holes. The drilling process
was evaluated based on a factor called the delamination factor, which is defined as the ratio of the maximum diameter of the
damage zone, measured using SEM, to the standard hole diameter (drill diameter). Analysis of variance of the experimental
results showed that cutting speed was the most significant parameter among the controllable parameters during drilling of
sandwich specimens followed by flank length and feed rate. Finally, confirmation tests were performed to make a comparison
between the experimental results and the correlation results. The damage mechanisms are explained using SEM. 相似文献
44.
Golla Narasimha Ayla Sridevi Golla Ramanjaneyulu 《International Journal of Food Properties》2016,19(3):652-661
Aspergillus niger, an isolate of soil contaminated with effluents from cotton ginning mill was grown in Czapek-Dox medium containing sawdust, Triton-X 100 and urea for production of an extracellular β-glucosidase. β-Glucosidase enzyme was purified (86-fold) from culture filtrate of A. niger by employing ammonium sulphate precipitation and gel filtration on sephadex G-75. The molecular mass of the purified enzyme was estimated to be 95 kDa by sodium dodecyl sulphate polyacrylamide gel electrophoresis. The enzyme had an optimal activity on p-nitrophenyl β-D-glucopyranoside at 50°C and pH 5.0. The Km and Vmax of the enzyme on p-nitrophenyl β-D-glucopyranoside at 50°C and pH 5 were 8.0 mM and 166 µmol/min/mg of protein, respectively. The enzyme could hydrolyze cellobiose and lactose but not sucrose. Heavy metals like Hg2+, Al3+, and Ag+ inhibited the activity, whereas Zn2+ and detergents such as Triton-X 100 and Tween-80 increased the activity at 0.01%. The enzyme activity increased in the presence of methanol and ethanol. 相似文献
45.
Madhusudhan C. K. Mahendra K. Raghavendra Narasimha Revanasiddappa M. Faisal Muhammad 《Journal of Materials Science: Materials in Electronics》2022,33(3):1366-1382
Journal of Materials Science: Materials in Electronics - The article focuses on the suitability of electrically characterized polypyrrole-banana carbon (PPy-BC) nanocomposites for broadband... 相似文献
46.
In ultrasonic machining (USM), brittle materials are machined by repeated impacts on the workpiece through a medium of abrasive slurry. Material removal rates are influenced by the various process parameters including the properties of the workpiece material. In this investigation, the influence of fracture toughness and hardness of workpiece materials are studied and reported. Fracture toughness is found to be an important parameter. Experiments are conducted with both conventional and rotary USM modes. Machining performance in the rotary mode is found to be much superior to the conventional mode. The results of static, sliding and rolling indentation tests reported by other investigators are used for explaining the importance of the fracture toughness. 相似文献
47.
Pandian M. Thurai Prasad Sarappadi Narasimha Sharma Manish 《Wireless Personal Communications》2021,120(4):2653-2691
Wireless Personal Communications - Radio frequency identification (RFID) is a promising and widespread wireless communication technology for entity identification or authentication. By the emerging... 相似文献
48.
The effect of doping iron at the yttrium site in hexagonal KCaY(PO4)2 is studied for various concentrations ofx (0≤x≤1), of iron using Mössbauer and X-ray diffraction methods. For low iron concentrations, very little changes in structure are seen but atx≈0·1, onset of new peaks in the XRD pattern is observed. The Mössbauer study of the doped samples reveals that iron has a solubility of up to 2·5% in the parent phase with any excess iron precipitating out to form a new and unknown phase. From a detailed analysis of the X-ray diffraction pattern (corresponding tox=1) of the latter phase, it is found that this phase is rhombohedral with the possible space groupR3. 相似文献
49.
Laboratory abrasion and erosion tests have been reported on permanent moulded austempered ductile iron with manganese as alloying element at three levels, i.e., 1%, 2% and 3%. The influences of Mn addition on the wear and tensile properties have been studied and discussed. The results indicate that with increase in Mn content from 1% to 2%, the abrasion and erosion volume losses are exhibiting decreasing trend. Further increase in Mn addition to 3% has resulted in an increase in wear losses. Same is the case with the tensile strength and percentage elongation properties. These data have been interpreted based on the structural features including graphite morphology. 相似文献
50.
G. R. Rajkumar M. Krishna H. N. Narasimha Murthy S. C. Sharma K. R. Vishnu Mahesh 《Journal of Materials Engineering and Performance》2012,21(7):1485-1490
The aim of this study was to experimentally investigate the effect of repeated low-velocity impacts on tensile strength of fiber metal laminates (FMLs) using instrumented drop weight impact tester. FMLs were fabricated layer by layer intercalating three layers of aluminum 6061 and two layers of glass fiber-reinforced epoxy. The FMLs were subjected to repeated low-velocity impacts (<10?m/s) at the same location on the FML. The degradation of mechanical property due to impact(s) was studied using Zwick UTM at distances of 0, 20, 40, and 60?mm from the impact point. Results indicate that ultimate tensile strength, failure strain, and ductility of all specimens initially decrease, and then remain constant with increase in number of impacts. A closer examination of impacted FML by scanning electron microscope indicates that thinning and shear fracture in aluminum layers, as well as delamination, and fiber failure in composites plies were present. 相似文献