Combined biological and chemical assessment of estrogenic activities in wastewater treatment plant effluents

Five wastewater treatment plant effluents were analyzed for known endocrine disrupters and estrogenicity. Estrogenicity was determined by using the yeast estrogen screen (YES) and by measuring the blood plasma vitellogenin (VTG) concentrations in exposed male rainbow trout (Oncorhynchus mykiss). While all wastewater treatment plant effluents contained measurable concentrations of estrogens and gave a positive response with the YES, only at two sites did the male fish have significantly increased VTG blood plasma concentrations after the exposure, compared to pre-exposure concentrations. Estrone (E1) concentrations ranged up to 51 ng L^–1, estradiol (E2) up to 6 ng L^–1, and ethinylestradiol (EE2) up to 2 ng L^–1 in the 90 samples analyzed. Alkylphenols, alkylphenolmonoethoxylates and alkylphenoldiethoxylates, even though found at µg L^–1 concentrations in effluents from wastewater treatment plants with a significant industrial content, did not contribute much to the overall estrogenicity of the samples taken due to their low relative potency. Expected estrogenicities were calculated from the chemical data for each sample by using the principle of concentration additivity and relative potencies of the various chemicals as determined with the yeast estrogen screen. Measured and calculated estradiol equivalents gave the same order of magnitude and correlated rather well (R ²=0.6).An erratum to this article can be found at     

Solvent structures around Na+ and Cl− ions in water

The structural orientation of water in the hydration shells of Na⁺ and Cl^– has been obtained from a Monte Carlo simulation of a 0.55 molal NaCl solution, using the MCY model for water. The probability of first shell coordination numbers has been calculated and is compared with data of previous studies using various model systems.

---

Zur Lösungsmittel-Struktur rund um Na⁺ und Cl^– Ionen in Wasser

Zusammenfassung Es wurde mittels einer Monte Carlo-Simulation einer 0.55 molalen NaCl-Lösung unter Verwendung des MCY-Modells für Wasser die Lösungsmittel-orientierung von Wasser in der Hydrat-Hülle von Na⁺ und Cl^–-Ionen erhalten. Die wahrscheinlichsten Koordinationszahlen der ersten Hydrat-Schale werden diskutiert und mit den Daten aus früheren Untersuchungen verschiedener Modellsysteme verglichen.

     

Crystallographic and Spectroscopic Evidence for an Intramolecular (OH … π)-Interaction

Crystallographic and spectroscopic evidence for an intramolecular (OH … π)-interaction in anti^9,10-10endo-hydroxy, 10exo-butyltricyclo [4.2.1.1^2.5]deca-3, 7-dien-9-one ( 1 ) is presented.     

Crystal Structure of 1,1,4,4-Tetrafluorocyclohexane at 95 K

The crystal structure of 1,1,4,4-tetrafluorocyclohexane has been determined from X-ray diffraction measurements at 95 K. Internal motion of the CF₂-group can be discerned from analysis of the atomic vibration tensors. The pattern of bond lengths suggests that an anomeric-effect type of interaction between antiperiplanar C,C- and C,F-bonds (as well as between C,H- and C,F-bonds) may be operative in this molecule.     

Global geometry optimization of small silicon clusters at the level of density functional theory

By an application to small silicon clusters Si _N (with N = 4,5,7,10) it is shown that truly global geometry optimization on an ab initio or density functional theory level can be achieved, at a computational cost of approximately 1–5 traditional local optimization runs (depending on cluster size). This extends global optimization from the limited area of empirical potentials into the realm of ab initio quantum chemistry. Received: 24 February 1998 / Accepted: 6 March 1998 / Published online: 17 June 1998     

Hierachically porous nanocrystalline cobalt oxide monoliths through nanocasting

Nanocrystalline cobalt oxide, Co(3)O(4), monoliths exhibiting hierarchical bimoidal porosity have been prepared by nanocasting of porous silica monoliths.     

Application of the isoselective relationship to diels-alder reactions

Diels-Alder reactions with “normal” and “reverse” electron demand” obey common isoselective relationships (Figure I).     

A quantum chemical investigation of CO, NF, SO, CF2 and their combination products

The combination products of the compounds CO, NF, SO and CF₂ have been investigated by semiempirical and ab initio SCF methods. The semiempirical standard procedures lead to satisfactory molecular geometries except for sulfur compounds. The stabilisation energies, however, are unreasonable. Ab initio calculations with minimal basis sets lead to more satisfactory results, as far as stabilisation energies are concerned.