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排序方式: 共有392条查询结果,搜索用时 15 毫秒
1.
κ‐Carrageenan hydrogel crosslinked with protonated polyethyleneimine (PEI+) and glutaraldehyde (GA) was prepared and evaluated as a novel biocatalytic support for covalent immobilization of penicillin G acylase (PGA). The method of modification of the carrageenan biopolymer is clearly illustrated using a schematic diagram and was verified by FTIR, elemental analysis, DSC, and INSTRON using the compression mode. Results showed that the gels' mechanical strength was greatly enhanced from 3.9 kg/cm2 to 16.8 kg/cm2 with an outstanding improvement in the gels thermal stability. It was proven that, the control gels were completely dissolved at 35°C, whereas the modified gels remained intact at 90°C. The DSC thermogram revealed a shift in the endothermic band of water from 62 to 93°C showing more gel‐crosslinking. FTIR revealed the presence of the new functionality, aldehydic carbonyl group, at 1710 cm?1 for covalent PGA immobilization. PGA was successfully immobilized as a model industrial enzyme retaining 71% of its activity. The enzyme loading increased from 2.2 U/g (control gel) to 10 U/g using the covalent technique. The operational stability showed no loss of activity after 20 cycles. The present support could be a good candidate for the immobilization of industrial enzymes rich in amino groups, especially the thermophilic ones. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
2.
Measurement of Inlet Drop Size Distribution of Secondary Dispersions by Laser Particle Size Analyzer
Knowledge of the Oil drop size distribution, in addition to the mean drop size, is necessary in order to characterize secondary dispersions. Furthermore, the capture efficiency for any drop flowing through a packed bed depends upon its Oil inlet drop diameter. The Oil/Water secondary dispersions produced by the centrifugal pump were analyzed at regular intervals during an experiment to ascertain the drop size distribution and to check that the feed to the coalescence bed was consistent. New techniques that were developed for measurement of drop size distribution of secondary dispersions using Laser Particle Size Analyzer, which consisted of (He/Ne) laser emitter and laser receiver and lenses. The Laser Particle Size Analyzer was fixed directly to the experimental equipment by using the special designed circular cell. The measurement of drop size distribution was done by computer system with application software package. The new mean drop diameter (i.e., d21) equation has been derived theoretically and the results that predicted from this equation exhibited a maximum error of ±15% from the experimental data. 相似文献
3.
ABSTRACTIn this study, an Egyptian siliceous/calcareous sedimentary phosphorite was subjected to beneficiation by unsophisticated economic means. The mineralogical and chemical examination showed that the ore sample is a typical example for the East Mediterranean phosphorites with 21.80% P2O5, 10.93% acid insoluble and 16.61% loss on ignition. The primary crushed sample was classified into three size fractions without any milling and they were separately subjected to an integrated attrition scrubbing study. Screening and classification on the 2.30 mm and 0.071 mm sieves were sequentially introduced with the attrition process. The effect of solid%, attrition speed and time were studied and optimized for each size fraction. Results showed that three products were produced and could be categorized according to their P2O5 content into the coarse tailing (+2.30 mm), the attrition concentrate (?2.30 + 0.071 mm) and the phosphate fines (?0.071 mm). The P2O5 contents of these products reached 12.24%, 28.72% and 18.77%, with P2O5 distribution reached 6.74%, 51.75% and 41.51%, respectively. A global P2O5 of 28.72% was obtained with a recovery of about 52%. A tentative flow-sheet for the whole process was postulated. 相似文献
4.
Some chemical changes in the composition and physical properties of palm oil products are discussed. The effects of bleaching
and deodorization on oxidative properties and possible isomerization and interesterification of the fatty acids were indicated
from laboratory refining experiments. Investigation of commercial samples of refined palm oil products showed that the conjugated
dienes and trienes formed are minimal, indicating the use of good quality raw materials and mild processing conditions. Very
little isomerization occurred in commercial refined products as indicated from the level oftrans acids, and changes in the POP to PPO triglycerides due to possible interesterification were insignificant. Changes in physical
properties were inevitable due to the removal of free fatty acids and diglycerides and to minor impurities. 相似文献
5.
Ye Liang Yan Susu Zhen Jialing Han Tian Ferdinando Hany Seppänen Tapio Alasaarela Esko 《Mobile Networks and Applications》2022,27(4):1688-1699
Mobile Networks and Applications - In recent years, physical violence detection has become a research hotspot in the area of human activity recognition. With the improvement and full coverage of... 相似文献
6.
Maureen Hany Mahmoud A. Mahmoud 《Quality and Reliability Engineering International》2016,32(5):1825-1835
We evaluate the performance of the Crosier's cumulative sum (C‐CUSUM) control chart when the probability distribution parameters of the underlying quality characteristic are estimated from Phase I data. Because the average run length (ARL) under estimated parameters is a random variable, we study the estimation effect on the chart performance in terms of the expected value of the average run length (AARL) and the standard deviation of the average run length (SDARL). Previous evaluations of this control chart were conducted while assuming known process parameters. Using the Markov chain and simulation approaches, we evaluate the in‐control performance of the chart and provide some quantiles for its in‐control ARL distribution under estimated parameters. We also compare the performance of the C‐CUSUM chart to that of the ordinary CUSUM (O‐CUSUM) chart when the process parameters are unknown. Our results show that large number of Phase I samples are required to achieve a quite reasonable performance. Additionally, the performance of the C‐CUSUM chart is found to be superior to that of the O‐CUSUM chart. Finally, we recommend the use of a recently proposed bootstrap procedure in designing the C‐CUSUM chart to guarantee, at a certain probability, that the in‐control ARL will be of at least the desired value using the available amount of Phase I data. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
7.
Helge Klippstein Hany Hassanin Alejandro Diaz De Cerio Sanchez Yahya Zweiri Lakmal Seneviratne 《Advanced Engineering Materials》2018,20(9)
8.
In this report we present for the first time strong evidence for autosomal-dominant inheritance of grant liver hemangiomas. Furthermore, we review the current literature about incidence, pathogenesis, clinics, as well as diagnostic and therapeutic aspects of LH. A large family of Italian origin is described where three female patients in three successive generations suffered from large symptomatic LH. In addition, two other female relatives exhibited asymptomatic LH on sonographic scans. The restriction of the disease to the female gender could be explained by a sex-dependent difference in penetrance or expressivity of a presumable "liver-hemangioma" gene, or by known proliferative factors such as female sex hormones. We also observed an increased incidence of adenomas of the thyroidea among members with or without LH of the presented family. This uncommon familial association has also not yet been described and its genetic aspects are discussed. 相似文献
9.
Hany F. EL Yamany Miriam A.M. Capretz David S. Allison 《Information and Software Technology》2010,52(2):220-236
One of the most significant difficulties with developing Service-Oriented Architecture (SOA) involves meeting its security challenges, since the responsibilities of SOA security are based on both the service providers and the consumers. In recent years, many solutions to these challenges have been implemented, such as the Web Services Security Standards, including WS-Security and WS-Policy. However, those standards are insufficient for the new generation of Web technologies, including Web 2.0 applications. In this research, we propose an intelligent SOA security framework by introducing its two most promising services: the Authentication and Security Service (NSS), and the Authorization Service (AS). The suggested autonomic and reusable services are constructed as an extension of WS-1 security standards, with the addition of intelligent mining techniques, in order to improve performance and effectiveness. In this research, we apply three different mining techniques: the Association Rules, which helps to predict attacks, the Online Analytical Processing (OLAP) Cube, for authorization, and clustering mining algorithms, which facilitate access control rights representation and automation. Furthermore, a case study is explored to depict the behavior of the proposed services inside an SOA business environment. We believe that this work is a significant step towards achieving dynamic SOA security that automatically controls the access to new versions of Web applications, including analyzing and dropping suspicious SOAP messages and automatically managing authorization roles. 相似文献
10.