Guideline for Measurement of Ozone Concentration in the Process Gas From an Ozone Generator

A joint meeting of members of the Quality Assurance Committees of the International Ozone Association Pan American Group (PAG), European-African Group (EAG), and Nippon Islands Group (NIG) was held in Oxford, Ohio on November 8 and 9, 1995. The purpose of the meeting was to establish a single, shared guideline for ozone concentration measurement in the gas phase and, in particular, from commercial ozone generators.     

Sustained nitrite accumulation in a membrane‐assisted bioreactor (MBR) for the treatment of ammonium‐rich wastewater

A membrane‐assisted bioreactor (MBR) for sustained nitrite accumulation is presented, treating a synthetic wastewater with total ammonium nitrogen (TAN) concentrations of 1 kg N m^?3 at a hydraulic retention time down to 1 day. Complete biomass retention was obtained by microfiltration with submerged hollow fibre membranes. A membrane flux up to 189.5 dm³ day^?1 m^?2 could be maintained at a suction pressure below 100 kPa. Nitrification was effectively blocked at the nitrite stage (nitritation), and nitrate concentration was less than 29 g N m^?3. The rate of aeration was reduced to obtain a mixture of ammonium and nitrite, and after adjusting this rate the TAN/NO₂‐N ratio in the reactor effluent was kept around unity, making it suitable for further treatment by anaerobic oxidation of ammonium with nitrite. After increasing again the rate of aeration, complete nitrification to nitrate recovered after 11 days. It is suggested that nitrite accumulation resulted from a combination of factors. First, the dissolved oxygen (DO) concentration in the reactor was always limited with concentrations below 0.1 g DO m^?3, thereby limiting nitrification and preventing significant nitrate formation. The latter is attributed to the fact that ammonium‐oxidising bacteria cope better with low DO concentrations than nitrite oxidisers. Second, the MBR was operated at a high ammonia concentration of 7–54 g N m^?3, resulting in ammonia inhibition of the nitrite‐oxidising microorganisms. Third, a temperature of 35 °C was reported to yield a higher maximum growth rate for ammonium‐oxidising bacteria than for nitrite‐oxidising bacteria. Nitrite oxidisers were always present in the MBR but were out‐competed under the indicated process conditions, which is reflected in low concentrations of nitrate. Oxygen limitation was shown to be the most important factor to sustain nitrite accumulation. Nevertheless, nitritation was possible at ambient temperature (22–24 °C), lower ammonia concentration (<7 g N m^?3) and when using raw nitrogenous wastewater containing some biodegradable carbon. Overall, application of the MBR for nitritation was shown to be a reliable technology. © 2003 Society of Chemical Industry     

International studies of human factors in teleinformatics

This paper presents the history and context of the COST II bis work on human factors in teleinformatics. It describes the technical developments to be expected in networked systems which will change the capabilities that will be available to users and discusses the range of human-factors issues which will arise if users are to be able to master complex systems. The paper concludes by reporting the early debates of the working group and the classification of issues which identified the problems requiring human-factors attention     

Zur Frage der Bestimmung des gebundenen und des sich bewegenden Stickstoffs in Stählen

Widersprüche bei der Bestimmung des an Legierungselemente gebundenen Stickstoffs. Verhalten des Stickstoffs beim Erhitzen von Stählen und Nitriden im Wasserstoffstrom. Bestimmung des beweglichen Stichstoffs durch coulometrische Titration des gebildeten Ammoniaks. Arbeitsweise und Analysenergebnisse.     

Traffic offences: Another approach to description and prediction

The study reported examines the question of the use of drivers' official records as predictors of future behavior, with a view to setting up criteria for selecting drivers for driver-improvement courses. All the potentially dangerous traffic offences committed by drivers in the canton of Geneva, Switzerland, were noted during a three months observation period, and the driver' histories (offences committed during the preceding five years) were analysed. The statistical method used is Benzécri's factor analysis of correspondences, leading to more subtle analyses of the various factors playing a role. Results concerning the link between type of offence and characteristics of drivers, as well as modification of drivers' habits over time, are reported.     

Determination of residual isopropanol and propylene glycol in soft drinks by glass capillary gas chromatography

European Food Research and Technology - A method is described for the quantitative determination of the residual solvents isopropanol and propylene glycol in soft drinks. The proposed methods are...     

Development and validation of a liquid chromatography-tandem mass spectrometry assay for the quantification of docetaxel and paclitaxel in human plasma and oral fluid

A quantitative method for the simultaneous determination of docetaxel (Taxotere), paclitaxel (Taxol), 6alpha-hydroxypaclitaxel, and p-3'-hydroxypaclitaxel in human plasma and oral fluid is developed and validated. Oral fluid (this term is now preferred to saliva) was sampled with a Salivette collection device. The procedure used a simple liquid/liquid extraction with methyl tert-butyl ether followed by LC-ESI-MS/MS. Gradient elution was applied and provided increased robustness to ion suppression by the drug formulation vehicle (polysorbate 80 and Cremophor EL). Adduct ion formation with sodium and potassium was noticed and controlled by mobile-phase optimization. The protonated analytes generated in the positive ion mode were monitored through multiple reaction monitoring. Calibration was performed by internal standardization with cephalomannine, and regression curves were constructed ranging between 2 and 1000 ng/mL in plasma and 0.125 and 62.5 ng/mL in oral fluid, using a weighing factor of 1/x2. The regression curves were quadratic for paclitaxel and docetaxel and linear for the paclitaxel metabolites. Accuracy varied from 91.3 to 103.6%, and imprecision did not exceed 12.7% for all analytes in plasma and oral fluid. In conclusion, a sensitive and robust method was obtained, which fulfilled all validation criteria.     

Bifurcation software in Matlab with applications in neuronal modeling

Many biological phenomena, notably in neuroscience, can be modeled by dynamical systems. We describe a recent improvement of a Matlab software package for dynamical systems with applications to modeling single neurons and all-to-all connected networks of neurons. The new software features consist of an object-oriented approach to bifurcation computations and the partial inclusion of C-code to speed up the computation. As an application, we study the origin of the spiking behaviour of neurons when the equilibrium state is destabilized by an incoming current. We show that Class II behaviour, i.e. firing with a finite frequency, is possible even if the destabilization occurs through a saddle-node bifurcation. Furthermore, we show that synchronization of an all-to-all connected network of such neurons with only excitatory connections is also possible in this case.