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31.
Determination of peroxide value by conventional difference and difference-derivative spectrophotometry 总被引:1,自引:0,他引:1
Alberto Lezerovich 《Journal of the American Oil Chemists' Society》1985,62(10):1495-1500
The spectrophotometric behavior of the system iodide-iodine-iodate-oxygen was studied, and a simple iodometric method to determine
peroxide value by conventional, difference or difference-derivative spectrophotometry was developed. The procedures are carried
out inside standard photometric cells containing iodide solution to which the sample is added. Absorbance or its first derivative
with respect to wavelength is measured to determine iodine concentration by means of calibration curves. No special care to
avoid iodide oxidation by atmospheric oxygen is necessary.
The method is applicable even to lipids that give emulsions with water, such as phosphatides, and precise results are obtained
even at low peroxide values.
The use of a digital spectrophotometer with data processing and programming facilities allowed development of an interactive
program for automatic operation, which is outlined. 相似文献
32.
Hydroprocessing of heavy petroleum feeds: Tutorial 总被引:1,自引:0,他引:1
33.
ED Schneiderman SM Willis CJ Kowalski TR Ten have 《Canadian Metallurgical Quarterly》1993,32(1):35-43
Sixty-five patients initially seropositive for IgM anti-phenolic glycolipid-I (PGL-I) antibodies were tested for antibody levels to PGL-I, lipoarabinomannan (LAM), and the 35-kDa protein of Mycobacterium leprae at regular intervals for up to 30 months following the commencement of multidrug therapy (MDT). There was a steady decline in IgM anti-PGL-I and anti-35-kDa antibody levels to a mean of 17% and 14%, respectively, of the starting level at 24 months. The development of type 1 and type 2 reactions or the presence of drug-resistant organisms in a small number of patients had no significant influence on the changes in antibody level. The rate of decline was similar in different disease categories, but a higher proportion of lepromatous patients remained seropositive at the end of 2 years of treatment than borderline tuberculoid patients. By contrast, the mean IgG anti-LAM antibody levels remained stable or increased. Again the occurrence of type 1 or type 2 reactions had no significant effect on antibody level over 2 years. Falls in the IgM anti-PGL-I antibody levels mirrored the falls in the bacterial index in individual patients and provide an additional parameter for monitoring the response to chemotherapy. 相似文献
34.
Trends in Hydrological Parameters of a Southern Brazilian Watershed and its Relation to Human Induced Changes 总被引:5,自引:1,他引:4
Moraes Jorge M. Pellegrino Giampaolo Q. Ballester Maria V. Martinelli Luiz A. Victoria Reynaldo L. Krusche Alex V. 《Water Resources Management》1998,12(4):295-311
The Piracicaba river basin is a subtropical watershed located in the southeastern region of Brazil. With an area of 12 400 km2, the basin is a typical example of new landscape resulting from development in tropical and sub-tropical regions: establishment of intensive industrial and agricultural processes were followed by significant population growth and water management. This scenario has led to significant increase in water demand and decrease in water quality. The main objective of this study is the detection of changes in the patterns of flow and precipitation in the basin, and its possible relation to man-induced changes. Statistical analyses were performed on records of precipitation, evapotranspiration and streamflow, from 1947 to 1991. Precipitation and evapotranspiration totals showed significant increasing trends for the entire basin. From eight streamflow gauge stations, half showed significant decreasing trend. The most probable cause of such trends is the export of water from the basin to the metropolitan region of São Paulo city. 相似文献
35.
H. W. M. Ten Hoopen W. L. J. Hinrichs G. H. M. Engbers J. Feijen 《Journal of materials science. Materials in medicine》1996,7(11):699-704
The effects of sterilization of dry heparinized Cuprophan hemodialysis membranes by means of ethylene oxide (EtO) exposure, gamma irradiation, or steam on the anticoagulant activity and chemical characteristics of immobilized heparin and the permeability of the membrane were investigated. Sterilization did not result in a release of heparin or heparin fragments from heparinized Cuprophan. Sterilization of heparinized Cuprophan by means of EtO exposure and gamma irradiation induced a slight, insignificant decrease of the anticoagulant activity. In contrast, steam-sterilized heparinized Cuprophan showed a higher anticoagulant activity than unsterilized heparinized Cuprophan, which was most likely caused by cleavage of some of the covalent bonds between heparin and Cupropha. The effects of sterilization on the permeability of unmodified Cuprophan and heparinized Cuprophan were compared. The permeability of unmodified Cuprophan for vitamin B12 (Vit B12) and sulfobromophthalein (SBP) was reduced by 20–35% after EtO exposure and gamma irradiation and was reduced by 90–95% after steam sterilization. The water permeability of unmodified Cuprophan remained the same after EtO exposure and gamma irradiation but also dramatically reduced after steam sterilization. These reductions were ascribed to the collapse of pores of the membrane. The permeability of heparinized Cuprophan was not affected by EtO exposure and gamma irradiation but dramatically reduced after steam sterilization, although to a lesser extent than in the case of unmodified Cuprophan. Apparently, the presence of immobilized heparin (partially) prevented the collapse of pores during sterilization. Gamma irradiation was recommended as the preferred method of sterilization for heparinized Cuprophan. 相似文献
36.
Hydrocarbon exploration risk evaluation through uncertainty and sensitivity analyses techniques 总被引:1,自引:0,他引:1
Paolo Ruffo Livia Bazzana Alberto Consonni Anna Corradi Andrea Saltelli Stefano Tarantola 《Reliability Engineering & System Safety》2006,91(10-11):1155-1162
The evaluation of the exploration risk in the oil industry is a fundamental component of the decision process related to the exploratory phase. In this paper the two basic components of the exploratory risk: trap geometry and trapped hydrocarbon quantities (fluid), are compounded in a single coherent uncertainty and sensitivity approach. The results clarify that the model geometry influences each Petroleum System Modeling step and that the geometric uncertainty is correlated with the fluid uncertainty. The geometric uncertainty evaluation makes use of geostatistical techniques that produce a number of possible realizations of the trap geometry, all compatible with available data. The evaluation of the fluid uncertainty, through a Monte Carlo methodology, allows us to compute the possible quantities of oil and gas, generated in a basin and migrated from the hydrocarbon source location to each single trap. The final result is the probability distribution of oil and gas for each trap in the basin, together with other useful indicators like: the hydrocarbon filling probability map, the closure probability map, the drainage area probability map, the spilling paths probabilities, the trap-filling scenarios. 相似文献
37.
Jos M. Moreno Maria A. Aramendía Alberto Marinas Jos M. Marinas Francisco J. Urbano 《Applied catalysis. B, Environmental》2005,59(3-4):275-283
The liquid-phase hydrodechlorination of 3-chloropyridine and chlorobenzene has been studied over alkali-modified zirconia-supported palladium catalysts. The modification of the ZrO2 with alkali metal carbonates improves the catalytic activity of the final palladium catalyst. Therefore, the larger the ionic radii (Li+ < Na+ < K+), the greater the catalytic activity (TOF) of the palladium catalyst. For 3-chloropyridine, hydrodechlorination proceeds without catalyst deactivation. This is explained as the result of the interaction of reaction products (pyridine and HCl) forming pyridinium chloride, thus avoiding the detrimental effect of HCl on the palladium particles. Catalytic hydrodechlorination of chlorobenzene over Pd catalysts exhibits an initial catalytic activity (TOF) much lower than that of 3-chloropyridine and the Pd catalysts deactivate as the reaction proceeds. Finally, chlorobenzene hydrodehalogenation has also been carried out in the presence of an equimolecular amount of pyridine resulting in a decrease in the initial reaction rate on the one hand, but also in an increase in final conversion on the other. 相似文献
38.
Alberto Carpinteri Bernardino Chiaia Simone Puzzi 《Engineering Fracture Mechanics》2007,74(17):2892-2896
Aim of this letter to the Editor is at replying to the criticisms raised by Ba?ant and Yavari [Ba?ant ZP, Yavari A. Is the cause of size effect on structural strength fractal or energetic - statistical? Engng Fract Mech 2005;72:1-31] against the fractal approach to the size-scale effects on the mechanical properties of materials and the concept of the Multi-Fractal Scaling Law presented by Carpinteri [Carpinteri A. Scaling laws and renormalization groups for strength and toughness of disordered materials. Int J Solids Struct 1994;31:291-302]. These criticisms will be analysed thoroughly, showing how they also contain some mistakes and misunderstandings. The presented elucidations should redirect the discussion to a more correct scientific debate. 相似文献
39.
Talita Moreira de Oliveira Nilda de Fátima Ferreira Soares Rodrigo Magela Pereira Kátia de Freitas Fraga 《Packaging Technology and Science》2007,20(2):147-153
Conservation of food products depends on product quality and packaging suitability. The objective of this work was to develop and evaluate the antimicrobial efficiency of natamycin‐incorporated film in the production process of Gorgonzola cheese. It aims to optimize the production process and increase shelf‐life and food safety for the consumer. Films with different concentrations of natamycin were produced and tested in Gorgonzola cheeses to evaluate its efficiency against Penicillium roqueforti on the cheese surface. Films with 2 and 4% natamycin presented satisfactory results for fungus inhibition and the amount of natamycin released to the cheese was below that allowed by the legislation. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
40.
Innovative activities are fundamental to the competitiveness strategies of the firms in a globalized market. Their assessment,
using indicators such as those utilized in the Community Innovation Survey (CIS), shows significant sectoral dispersion. Traditional
industries are in a weak position because the innovation they are involved in is mainly aesthetic, which is not really addressed
in innovation surveys. In this work, we review the various criticisms levelled at existing indicators and propose some new
indicators that would capture the types of innovations that are conducted by the traditional industries. This work is based
on a study of the features of traditional industries and the concept of aesthetic novelty. The proposed indicators are tested
in the Spanish footwear industry. 相似文献