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Used Chemical (used + chemical)
Selected AbstractsWater Framework Directive: ecological classification of Danish lakesJOURNAL OF APPLIED ECOLOGY, Issue 4 2005MARTIN SØNDERGAARD Summary 1The European Water Framework Directive (WFD) requires that all European waterbodies are assigned to one of five ecological classes, based primarily on biological indicators, and that minimum good ecological quality is obtained by 2015. However, the directive provides only general guidance regarding indicator definitions and determination of boundaries between classes. 2We used chemical and biological data from 709 Danish lakes to investigate whether and how lake types respond differently to eutrophication. In the absence of well-defined reference conditions, lakes were grouped according to alkalinity and water depth, and the responses to eutrophication were ordered along a total phosphorus (TP) gradient to test the applicability of pre-defined boundaries. 3As a preliminary classification we suggest a TP-based classification into high, good, moderate, bad and poor ecological quality using 0,25, 25,50, 50,100, 100,200 and > 200 µg P L,1 boundaries for shallow lakes, and 0,12·5, 12·5,25, 25,50, 50,100 and > 100 µg P L,1 boundaries for deep lakes. Within each TP category, median values are used to define preliminary boundaries for the biological indicators. 4Most indicators responded strongly to increasing TP, but there were only minor differences between low and high alkalinity lakes and modest variations between deep and shallow lakes. The variability of indicators within a given TP range was, however, high, and for most indicators there was a considerable overlap between adjacent TP categories. Cyanophyte biomass, submerged macrophyte coverage, fish numbers and chlorophyll a were among the ,best' indicators, but their ability to separate different TP classes varied with TP. 5When using multiple indicators the risk that one or more indicators will indicate different ecological classes is high because of a high variability of all indicators within a specific TP class, and the ,one out , all out' principle in relation to indicators does not seem feasible. Alternatively a certain compliance level or a ,mean value' of the indicators can be used to define ecological classes. A precise ecological quality ratio (EQR) using values between 0 and 1 can be calculated based on the extent to which the total number of indicators meets the boundary conditions, as demonstrated from three Danish lakes. 6Synthesis and applications. The analysis of Danish lakes has identified a number of useful indicators for lake quality and has suggested a method for calculating an ecological quality ratio. However, it also demonstrates that the implementation of the Water Framework Directive faces several challenges: gradual rather than stepwise changes for all indicators, large variability of indicators within lake classes, and problems using the one out , all out principle for lake classification. [source] Onion Cells After High Pressure and Thermal Processing: Comparison of Membrane Integrity Changes Using Different Analytical Methods and Impact on Tissue TextureJOURNAL OF FOOD SCIENCE, Issue 7 2010Maria E. Gonzalez Abstract:, Two different analytical methods were evaluated for their capacity to provide quantitative information on onion cell membrane permeability and integrity after high pressure and thermal processing and to study the impact of these processing treatments on cell compartmentalization and texture quality. To determine changes in cell membrane permeability and/or integrity the methodologies utilized were: (1) measurement of a biochemical product, pyruvate, formed as a result of membrane permeabilization followed by enzymatic activity and (2) leakage of electrolytes into solution. These results were compared to previously determined methods that quantified cell viability and 1H-NMR T2 of onions. These methods allowed for the monitoring of changes in the plasma and tonoplast membranes after high pressure or thermal processing. High pressure treatments consisted of 5 min holding times at 50, 100, 200, 300, or 600 MPa. Thermal treatments consisted of 30 min water bath exposure to 40, 50, 60, 70, or 90 °C. There was strong agreement between the methods in the determination of the ranges of high pressure and temperature that induce changes in the integrity of the plasma and tonoplast membranes. Membrane rupture could clearly be identified at 300 MPa and above in high pressure treatments and at 60 °C and above in the thermal treatments. Membrane destabilization effects could already be visualized following the 200 MPa and 50 °C treatments. The texture of onions was influenced by the state of the membranes and was abruptly modified once membrane integrity was lost. Practical Application:, In this study, we used chemical, biochemical, and histological techniques to obtain information on cell membrane permeability and onion tissue integrity after high pressure and thermal processing. Because there was strong agreement between the various methods used, it is possible to implement something relatively simple, such as ion leakage, into routine quality assurance measurements to determine the severity of preservation methods and the shelf life of processed vegetables. [source] FS06.7 The new fragrance mix II , test results of a multicentre European StudyCONTACT DERMATITIS, Issue 3 2004Peter Frosch A new fragrance mix (FM II) with 6 frequently used chemicals was evaluated in consecutive patients patch tested in 6 dermatological centres in Europe. 28% FM II contained 5% Lyral, 1% citral, 5% farnesol, 5% coumarin, 1% citronellol and 10% alpha-hexyl cinnamic aldehyde (AHCA); in 14% FM II the single constituents' concentrations was lowered to 50% and in 2.8% FM II to 10%. Each patient was classified regarding a history of adverse reactions to fragrances: certain, probable, questionable and none. The frequency of positive reactions to the currently used 8% fragrance mix (FM I) and the new mix in 1703 patients was as follows: FM I, 6.6%; 2.8% FM II, 1.3%; 14% FM II, 2.9%; 28% FM II, 4.1%. The number of doubtful/irritant reactions was 7.2% for FM I and ranged from 1.8% to 10.6% for FM II. 8.7% of tested patients had a certain fragrance history. Of these 25.2% were positive to FM I, reactivity to FM II was dose-dependent and ranged from 8.1% to 17.6% in this subgroup. Comparing 2 groups of history , certain and none , values for sensitivity (sens) and specificity (spec) were calculated. Sens: FM I, 27.2%; 2.8% FM II, 8.7%; 14% FM II, 15.9%; 28% FM II, 21.5%. Spec: FM I, 96.3%; 2.8% FM II, 99.5%; 14% FM II, 98.7%; 28% FM II, 97.9%. 31/70 (44.3%) patients positive to 28% FM II were negative to FM I. In the group of patients with a certain history a total of 6 patients was found reacting only to FM II. Simultaneous break-down testing with the single constituents produced positive reactions in 54.3% for 28% FM II and 48% for 14% FM II. Lyral was the dominating single constituent with positive reactions (37.1% for 28% FM II, 36% for 14% FM II), followed by citral, farnesol, citronellol, AHCA and coumarin. Chemical analysis for the 6 constituents of FM II was performed on 25 products used by 12 patients being patch test positive to FM II. Lyral was detected in 76% of these products, citral in 16% and AHCA in 8%. In conclusion, the new FM II detects additional patients with contact allergy to fragrances missed by the currently used FM I. The medium concentration, 14% FM II, is probably the most useful one for diagnostic screening. [source] Terminal and transient drop rise velocity of single toluene droplets in waterAICHE JOURNAL, Issue 1 2010Mirco Wegener Abstract The knowledge of the drop rise velocity in dispersed systems is of fundamental importance. Especially, the residence time is needed for calculation of mass transfer rates in extraction columns. This work deals with fluid dynamic measurements of toluene droplets rising in water ranging from 1.0 to 7.0 mm, with the premise of high purity of the used chemicals. The toluene/water-system is widely used as a test system with high interfacial tension. A semiempirical correlation for pure systems to predict the terminal velocity of single rising/falling droplets based on experimental data is presented. Results show that a distinction between maximum and characteristic mean values of the drop rise velocity is necessary, especially in the diameter range 2.4,3.0 mm where unexpected velocity fluctuations occur. Two distinct terminal rise velocities were observed for 3 mm droplets. Furthermore, comparisons of the Weber-Reynolds-correlation and the drag coefficient with correlations from literature show good agreement. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] | ||||||||||