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排序方式: 共有206条查询结果,搜索用时 31 毫秒
11.
Rim Khlifi Sami Sayadi Lassaad Belbahri Steve Woodward Tahar Mechichi 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2009,84(12):1828-1833
BACKGROUND: This study concerns the assessment of laccase stability during textile industry effluent treatment by laccase in the presence of a mediator RESULTS: The effects of 1‐hydroxybenzotriazole (HBT) and textile wastewater on the stability of a crude laccase prepared from cultures of Trametes trogii during the process of textile industry effluent decolourization were determined. HBT was essential for decolourization of effluent by laccase. Decolourization efficiency decreased when effluent was repeatedly added to the reaction mixture, suggesting inhibition of laccase during the process. Stability of the laccase was not affected by different concentrations of effluent, but inactivation was proportional to HBT concentration. CONCLUSION: Experimental results showed that a redox mediator such as HBT was required for high decolourization rate of textile industry effluent; however free radicals generated from this compound inactivated the laccase used in the process. Copyright © 2009 Society of Chemical Industry 相似文献
12.
Photodegradation of phenol red in the presence of oxyhydroxide of Fe(III) (Goethite) under artificial and a natural light 下载免费PDF全文
Sara Belattar Nadra Debbache Imen Ghoul Tahar Sehili Ala Abdessemed 《Water and Environment Journal》2018,32(3):358-365
The (α‐FeOOH) Goethite composite is a stable and an efficient catalyst in aqueous suspension under irradiation at 365 nm and by solar light. The photocatalytic activities of this composite were evaluated using Phenol Red (PR) dye (phenolsulfonphthalein class). In the dark, controlling factors, such as the pH and the adsorption of PR on Goethite surface were evaluated (before starting the photochemical experiments). It was found that the system PR‐Goethite present a small decrease in the main band of the dye (435 nm) which was explained by the low rate of adsorption of this dye on the Goethite. Also, we note that 40% of PR decolourisation was obtained after 200 min by the system PR‐Goethite‐hydrogen peroxide (H2O2) in dark due to the formation of ?OH by thermal decomposition of H2O2 on the surface of Goethite. The effects of various experimental parameters, such as initial dye concentration, pH, photocatalyst amount, tert‐Butyl alcohol effect and H2O2 addition were investigated in the study of photodegradation of the dye. The results showed that the photodegradation of PR under UV‐A (365 nm) irradiation could be enhanced greatly in the presence of H2O2. Natural radiation tests (under sunlight) showed that degradation was faster comparing with that obtained using the artificial one at 365 nm. Studies of the mineralization using total organic carbon method under naturel light certify that this method, compatible with the environment, may be considered in the treatment of wastewater and generally in the process of removal of this kind of pollutant. 相似文献
13.
Today’s analog/RF design and verification face significant challenges due to circuit complexity, process variations and short
market windows. In particular, the influence of technology parameters on circuits, and the issues related to noise modeling
and verification still remain a priority for many applications. Noise could be due to unwanted interaction between the circuit
elements or it could be inherited from the circuit elements. In addition, manufacturing disparity influence the characteristic
behavior of the manufactured circuits. In this paper, we propose a methodology for modeling and verification of analog/RF
designs in the presence of noise and process variations. Our approach is based on modeling the designs using stochastic differential
equations (SDE) that will allow us to incorporate the statistical nature of noise. We also integrate the device variation
due to 0.18μ
m fabrication process in an SDE based simulation framework for monitoring properties of interest in order to quickly detect
errors. Our approach is illustrated on nonlinear Tunnel-Diode and a Colpitts oscillator circuits. 相似文献
14.
To compare the relative impact of dietary lauric acid (12∶0) and palmitic acid (16∶0) on plasma lipids, two fat-sensitive
species, Mongolian gerbils and cebus monkeys, were fed cholesterol-free, purified diets enriched with either 12∶0-rich or
16∶0-rich fats, while all other fatty acids were held constant by selective blending of up to five natural fats or oils. The
two gerbil diets (40 en% from fat) allowed for an 8 en% exchange between 12∶0 and 16∶0, and the monkey diets (31 en% from
fat) allowed for 6 en% exchange beteen these two fatty acids. Eight gerbils received the diets for eight weeks, and 12 cebus
monkeys were fed each diet in a cross-over design for up to 22 wk. Both diets resulted in similar plasma cholesterol, triglyceride,
and high density lipoprotein cholesterol concentrations within each species. Additionally, separation of cebus lipoproteins
by discontinuous density-gradient ultracentrifugation failed to show any dietary differences in concentration or composition
of the three major lipoprotein classes (d<1.019, 1.019–1.055, and 1.055–1.168 g/mL). Thus, in two species sensitive to manipulations
in dietary fat while consuming cholesterol-free diets, 16∶0 was not hypercholesterolemic relative to 12∶0.
Based on a paper presented at the PORIM International Palm Oil Congress (PIPOC) held in Kuala Lumpur, Malaysia, September
1993. 相似文献
15.
The anodic oxidation of 3,3′-dimethoxybenzidine and its derivatives were studied by cyclic voltammetry, voltammetry at a rotating platinum electrode, chronopotentiometry and constant potential coulometry. The exhaustive oxidation of 3,3′-dimethoxybenzidine led at the potential of the first oxidation peak and second oxidation peak, respectively, to a stable cation radical salt (characterized by ESR spectroscopy) and to a quinone-diimine. Whereas, 3,3′-dimethoxy-N,N,N′,N′-tetramethylbenzidine afforded directly a dication salt owing to potential inversion 3,3′-dimethoxy-N,N,N′,N′-tetraethylbenzidine gave the corresponding soluble cation radical salt. 相似文献
16.
Electropolymerization of phenol on a vitreous carbon electrode in acidic aqueous solution at different temperatures 总被引:1,自引:0,他引:1
Noureddine?Belhadj Tahar André?SavallEmail author 《Journal of Applied Electrochemistry》2011,41(8):983-989
Electrochemical oxidation of phenol in acidic aqueous solution was studied on a vitreous carbon electrode at different temperatures
in the range of 25–85 °C by cyclic voltammetry and chronoamperometry. The kinetic aspect of the phenol oxidation was investigated
as a function of its concentration and temperature. The electrode deactivation by formation of an adherent, compact, and insulating
polymeric film was examined by monitoring the decrease in the peak current of phenol oxidation during the course of successive
potential scans. Repeated potential scans in the region of water stability did not reactivate the electrode whatever the temperature
used. Chronoamperometric curves recorded at different potentials in the region of water decomposition shown that the electrochemical
activity of the electrode was partially restored even when performed at low temperature (25 °C). 相似文献
17.
L. Ben Tahar M. Artus F. Herbst S. Ammar F. Fiévet 《Materials Research Bulletin》2007,42(11):1888-1896
Pure nanoparticles of the CoFe2−xRExO4 (RE = Gd, Sm; x = 0.0, 0.1) system have been prepared by forced hydrolysis in polyol. The insertion of Sm3+ and Gd3+ cations into the cobalt ferrite structure has been investigated. X-ray micro-analysis (EDX) shows that the RE contents are close to the nominal ones. X-ray diffraction (XRD) evidences a cell size increase with slight distortions in the spinel-like lattice indicating the entrance of RE3+ ions. Micro-Raman spectroscopy confirms the cubic inverse-spinel structure and rules out the existence of impurities like hematite. Magnetic measurements (SQUID) show important differences in the magnetic properties of the unsubstituted and substituted particles. All the particles are superparamagnetic at room temperature and ferrimagnetic at low temperature. However, their main magnetic characteristics appear to be directly dependent on the RE content. 相似文献
18.
Probabilistic techniques are widely used in the analysis of algorithms to estimate the computational complexity of algorithms
or a computational problem. Traditionally, such analyses are performed using paper-and-pencil proofs and the results are sometimes
validated using simulation techniques. These techniques are informal and thus may result in an inaccurate analysis. In this
paper, we propose a formal technique for analyzing the expected time complexity of algorithms using higher-order-logic theorem
proving. The approach calls for mathematically modeling the algorithm along with its inputs, using indicator random variables,
in higher-order logic. This model is then used to formally reason about the expected time complexity of the underlying algorithm
in a theorem prover. The paper includes the higher-order-logic formalization of indicator random variables, which are fundamental
to the proposed infrastructure. In order to illustrate the practical effectiveness and utilization of the proposed infrastructure,
the paper also includes the analysis of algorithms for three well-known problems, i.e., the hat-check problem, the birthday
paradox and the hiring problem. 相似文献
19.
Correlations in the properties of Albanian coals 总被引:1,自引:0,他引:1
Seventeen Albanian brown coals were analyzed in detail and their properties were compared on both a national and regional basis. The measurements made were moisture, proximate and ultimate analyses, sulfur forms, bituminous matter, humic acids and specific energy, plus Gray-King and free-swelling tests. Linear correlations were derived amongst these coal properties on both dry and dry-ash-free basis. The resulting equations would allow the prediction of many coal properties from a limited number of experimental measurements. 相似文献
20.
The evaluation of meat spoilage is based on sensory and microbiological analyses. The disadvantages of sensory analyses are its reliance on highly trained panelists, a procedure which makes it costly and unattractive for routine analyses. Moreover, the classical microbiological analyses are lengthy, costly and destructive. In this study a portable fluorescence spectrometer was tested to quantify minced beef spoilage. This study was investigated on samples stored aerobically and under vacuum at 5 and 15 °C. Total viable counts (TVC), Pseudomonas, lactic acid bacteria, and yeast/molds counts were investigated with classical culture methods. Fluorescence spectra were recorded on the same samples using different excitation LEDs (280, 320, and 380 nm). PLS-R with leave-one-out cross validation was used to perform calibration and validation models. The PLS-R models presented good R2(CV) (0.50-0.99) and ratio of standard deviation (RPD(CV): 1.40-8.95) values after cross-validation. It could be concluded that portable spectrofluorimeters are promising devices to evaluate spoilage in minced beef. 相似文献