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91.
A method is described for converting chitosan into a high surface area and porous active carbon using a Na2CO3 solution impregnated into a partly depolymerized, protonated and water soaked chitosan. The wet chitosan paste is heat treated and transformed into a nonporous solid i.e. a carbon-rich matrix with uniformly suspended Na2CO3 nanocrystallites. Subsequent HCl etching opens cavities in the matrix due to the removal of the Na2CO3. The active carbon is high surface area (above 400 m2/g), microporous (below 1 nm) and nitrogen-rich (above 6% atomic). 相似文献
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Jerzy Falandysz Aneta Mazur Anna K Kojta Grażyna Jarzyńska Małgorzata Drewnowska Anna Dryżałowska Innocent C Nnorom 《Journal of the science of food and agriculture》2013,93(4):853-858
BACKGROUND: This paper reports data on bioconcentration potential and baseline mercury concentrations of fruiting bodies of dark honey fungus (Armillaria solidipes) Peck and soil substrate layer (0–10 cm) from 12 spatially distant sites across Poland. Mercury content of caps, stipes and soil samples were determined using validated analytical procedure including cold‐vapor atomic absorption spectroscopy after thermal decomposition of the sample matrix and further amalgamation and desorption of mercury from gold wool. RESULTS: Mean mercury concentrations ranged from 20 ± 8 to 300 ± 70 ng g?1 dry weight (dw) in caps, from 20 ± 6 to 160 ± 40 ng g?1 dw in stipes, and in underlying soil were from 20 ± 2 to 100 ± 130 ng g?1 dw. The results showed that stipes mercury concentrations were 1.1‐ to 1.7‐fold lower than those of caps. All caps and the majority of stipes were characterized by bioconcentration factor values > 1, indicating that dark honey fungus can be characterized as a moderate mercury accumulator. CONCLUSION: Occasional or relatively frequent eating of meals including caps of dark honey fungus is considered safe in view of the low total mercury content, and the mercury intake rates are below the current reference dose and provisionally tolerable weekly intake limits for this hazardous metal. © 2012 Society of Chemical Industry 相似文献
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Danuta Krupa Jacek Baszkiewicz Jerzy Smolik Janusz W. Sobczak 《Surface & coatings technology》2010,205(6):1743-8968
This paper is concerned with the surface modification of titanium by the PEO method (plasma electrolytic oxidation) in the solutions which contain Ca, P, Si and Na. The chemical composition of the thus formed surface layers was examined by XPS and EDS. The morphology of the surface was observed by SEM. The phase composition was determined by X-ray diffraction (XRD). The adhesive strength of the oxide layers was evaluated by the scratch-test. The corrosion resistance was determined in a simulated body fluid (SBF) at a temperature of 37 °C by electrochemical methods for various exposure times.The oxide layers obtained were porous and enriched with Ca, P, Si and Na and their properties depended on the electrolyte solution and the parameters of the oxidation process. The results of the electrochemical examinations show that the surface modification by PEO does not worsen the corrosion resistance of titanium after a 13 h exposure in SBF. The electrochemical impedance spectroscopy (EIS) results indicate that the surface layers have a complex structure and that their electric properties undergo changes during long-term exposures in SBF. 相似文献
96.
Eugeniusz Rusiński Jerzy Czmochowski Artur Iluk Marcin Kowalczyk 《Engineering Failure Analysis》2010,17(1):179-191
A bucket wheel excavator (BWE) collapsed in a brown coal mine. As a result of a tie rod fracture the counterweight boom, the discharge boom and several other components of the other assemblies underwent plastic deformation. This paper presents the results of computer simulations of the collapse. A finite element method analysis of the counterweight boom tie rod showed stress concentrations exceeding the allowable level. Also material tests of the fracture surface were carried out to identify the causes of the collapse. Macroscopic and microscopic images of areas within the fracture were obtained. Measurements of hardness and microhardness in the vicinity of the weld were performed. The FEM analyses and material tests showed that the causes of the collapse were design and welding faults. 相似文献
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Jerzy Hapanowicz 《Flow Measurement and Instrumentation》2010,21(3):284-291
This paper covers the phase inversion phenomenon which occurs when an unstable, two-phase liquid–liquid system flows through a horizontal pipe. A short review has been provided for the methods applicable when establishing inversion conditions for stable emulsion systems. As regards phase inversion which takes place in unstable, liquid dispersion systems, the course and findings from our experiments have been described. The experiments involved the mixtures formed by water and four types of oil, and various methods were used for determination of the type of the liquid–liquid system, as well as conditions at which inversion occurred. The experimental findings made it possible to develop a method for determination of the type of an unstable liquid–liquid system which is just flowing, and hence for unequivocal indication of the types of continuous and disperse phases. The suggested method can be easily employed in practice since only the physical properties of both liquids and their mass flux densities need to be taken into consideration. 相似文献
99.
International Maritime Organization regulations forces ship owners to measure NOx emission from ship engines, but standard equipped engine rooms has not installed any usable apparatus to analyze of exhaust gases. In this paper, we propose a method of NOx emission estimation based on the measurements of working parameters of two-stroke ship engine. This estimation consists of both the model enabling to determine a temperature and model of composition of a gas mixture in the combustion chamber of the engine. Application of such model does not require carrying out direct measurements of engine exhaust gases by exhaust gas analyzers. For the developed method, results of engine working parameters should be sufficient to estimate the NOx emission according to IMO regulations. 相似文献
100.