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Laboratory toxicity tests are a key component of the aquatic risk assessments of chemicals. Toxicity tests with Myriophyllum spicatum are conducted based on working procedures that provide detailed instructions on how to set up the experiment, e.g., which experimental design is necessary to get reproducible and thus comparable results. Approved working procedures are established by analyzing numerous toxicity tests to find a compromise between practical reasons (e.g., acceptable ranges of ambient conditions as they cannot be kept completely constant) and the ability for detecting growth alterations. However, the benefit of each step of a working procedure, e.g., the random repositioning of test beakers, cannot be exactly quantified, although this information might be useful to evaluate working procedures. In this paper, a growth model of M. spicatum was developed and used to assess the impact of temperature and light fluctuations within the standardized setup. It was analyzed how important it is to randomly reassign the location of each plant during laboratory tests to keep differences between the relative growth rates of individual plants low. Moreover, two examples are presented on how modeling can give insight into toxicity testing. Results showed that randomly repositioning of individual plants during an experiment can compensate for fluctuations of light and temperature. A method is presented on how models can be used to improve experimental designs and to quantify their benefits by predicting growth responses.

Effects of chemicals are, in most cases, caused by internal concentrations within organisms which rely on uptake and elimination kinetics. These processes might be key components for assessing the effects of time-variable exposure of chemicals which regularly occur in aquatic systems. However, the knowledge of toxicokinetic patterns caused by time-variable exposure is limited, and gaining such information is complex. In this work, a previously developed mechanistic growth model of Myriophyllum spicatum is coupled with a newly developed toxicokinetic part, providing a model that is able to predict uptake and elimination of chemicals, as well as distribution processes between plant compartments (leaves, stems, roots) of M. spicatum. It is shown, that toxicokinetic patterns, at least for most of the investigated chemicals, can be calculated in agreement with experimental observations, by only calibrating two chemical- specific parameters, the cuticular permeability and a plant/water partition coefficient. Through the model-based determination of the cuticular permeabilities of Isoproturon, Iofensulfuron, Fluridone, Imazamox and Penoxsulam, their toxicokinetic pattern can be described with the model approach. For the use of the model for predicting toxicokinetics of other chemicals, where experimental data is not available, equations are presented that are based on the log (P oct/wat) of a chemical and estimate parameters that are necessary to run the model. In general, a method is presented to analyze time-variable exposure of chemicals more in detail without conducting time and labour intensive experiments.

The leaching of the herbicide isoproturon and the water tracer bromide in the profile of a silty loam soil at the Weiherbach Catchment area in Germany was simulated by eight different persons using the models MACRO, SIMULAT, LEACHP, WAVE, GLEAMS and PELMO (only bromide). Experimental results from different laboratory studies and from a field study were available to parameterise the models. Model results concerning water contents, tracer and pesticide profiles were provided for two different test periods in the field (winter and spring). The results for the behaviour of the herbicide and the tracer in the field study in spring were not known beforehand to the model users. Therefore this is considered to be a blind test. After the model users had estimated the parameters and presented the modelling results a consensus parameter set was provided by the data set co-ordinator to reduce the subjective influence of individual users and to identify the effect of different model concepts. The most striking points of the modelling exercise were the diversity of parameters estimated by different modellers from the same basic data set and the problems of simulating the field behaviour using laboratory derived pesticide parameters. An overwhelming influence of the individual users on the model results was remarkable for the Weiherbach data set. It was not possible to estimate, from the laboratory data, alone a parameter combination suitable for describing the field behaviour of isoproturon satisfactorily. The use of literature data or calibration to the field results of the winter period did improve the simulation results significantly.

The crystal structures of two borines were solved by direct methods and refined by full-matrix least-squares procedure. 6-methyl-4-phenyl-1,3,2-(2H)-2,2-difluorodioxaborine, C10H9BF2O2 (compound 1): orthorhombic, space group Pnma, a = 12.534(2) Å, b = 7.109(2) Å, c = 10.933(2) Å, V = 974.2(3) Å3, Z = 4 and d = 1.43Mg m−3, R = 0.039 (Rw = 0.036) for 88 parameters and 752 observations with I > 3σ(I). 4-(p-anisyl)-6-methyl-1,3,2-(2H)-2,2-difluorodioxaborine, C11H11BF2O3 (compound 2): monoclinic, space group P21/m, a = 6.8889(8) Å, b = 7.071(1) Å, c = 11.695(2) Å, β = 98.55(1)°, V = 563.3(9) Å3, Z = 2 and d = 1.42Mg m−3, R = 0.039 (Rw = 0.036) for 100 parameters and 1003 observations with I > 3σ(I). The crystal structure analysis of compound 1 and 2 reveals that the difference in their absorption and fluorescence spectra, by going from solution to the solid state, reflects their packing in the crystal lattice which enables a charge transfer process to be developed between two planar molecules at ca. 3.5 Å from each other in two different but parallel planes.

Selbsterfahrung in der Ausbildung zum Verhaltenstherapeuten ist in die Diskussion geraten. Der folgende Beitrag greift bisher bekannte Curricula dazu auf, stellt ein eigenes erprobtes Konzept fur Selbsterfahrung vor und will zu einer breiteren Meinungsbildung sowie zur Uberprufung mit empirischen Mitteln anregen. Das beschriebene Modell basiert auf drei miteinander vernetzten Teilen: Der Erfahrung mit dem Gruppenprozeβ (prozeβorientierte Inhalte), der Erarbeitung von personlichen Inhalten aus der Lebensgeschichte, der Selbstmodifikation und dem aktuellen Verhalten (personenbezogene Inhalte) sowie der Erforschung von Auswirkungen personlichen Verhaltens auf therapeutische Situationen (berufsbezogene Inhalte). Notwendige Zielorientiertheit wird zugunsten eigener Produktivitat relativiert, die Arbeit am Prozeβ wird starker gewichtet. Die Auswertung einer Ratingskala, die den Teilnehmern als baseline und retest gegeben wurde, ergab, daβ das durchgefuhrte Konzept die Erwartung der Teilnehmer, sich auf Selbsterfahrung einlassen zu konnen, «blinde Flecken» kennenzulernen und mit Klienten bewuβter umgehen zu konnen, weitgehend erfullt. Es werden Vorschlage fur eine weitere Ausgestaltung und Verbesserung in diesem Ausbildungsteil gemacht.

Results from a long-term study on leaching and transformation of the herbicide glufosinate-ammonium (ammonium-DL-homoanalin-4-yl (methyl)phosphinate) in a layered soil column were compared with model calculations. Soil columns with layers of loamy sand and sand were treated with 3 kg/ha glufosinate-ammonium, applied to the soil surface. The soils were irrigated and the leachate was monitored for glufosinate-ammonium and the main metabolite 3-methylphosphinico-propionic acid during a period of 256 d. Calculations for glufosinate-ammonium and the metabolite were performed with the soil column model EXSOL. Linear equilibrium sorption coefficients (Kd) and first-order half-lives were used for fitting effluent curves for both the herbicide and the metabolite. Sorption coefficients were compared with those values estimated from a relation to the clay content derived from batch studies. Fitted half-lives were compared with the results from die-away and 14CO2 evolution studies of both the parent and the daughter compound. The observed leaching of glufosinate-ammonium could be well simulated using Kd (0.5 cm3/g) and half-life (11.2 d). The half-life fitted for the metabolite (10–30 d) was a factor 2 to 3 smaller than that measured with batch degradation experiments. This may be the result of using degradation data estimated by 14CO2 evolution, which only indirectly indicates the disappearance of the compound.

The paper presents a summary of different synthetic approaches to the Silaneophane Hoe 084498, which is a new Silicon based insecticide with promising efficiency in the protection of important crops, especially rice. In addition, some biological, ecological and toxicological data are given.