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New cementitious materials based on calcium hydrosilicate hydrates were recently developed as potential substitutes for ordinary portland cement, but with a reduced CO 2 footprint. The materials are produced by hydrothermal processing of SiO 2 and Ca(OH) 2 , giving rise to calcium silicate hydrates, followed by mechanical activation of the latter via cogrinding with various siliceous materials. Thus, the chemical composition in terms of C/S ratio could be adjusted over a broad range (1-3). In this study the synthesis of a previously unknown cementitious material produced via the combination of mechanical activation in a laboratory mill and thermal treatment of a mixture of quartz and hydrothermally synthesized calcium silicate hydrates: a-Ca 2 [HSiO 4 ](OH) (a-C 2 SH) and Ca 6 [Si 2 O 7 ] (OH) 6 (jaffeite) are reported. It forms independently of the type of mill used (eccentric vibrating mill, vibration grinding mill) after thermal treatment of the ground materials at 360°C-420°C. The new material is X-ray amorphous and possesses a CaO/SiO 2 ratio of 2. A characteristic feature in regards to the silicate anionic structure is the increased silicate polymerization (up to 27% Si 2 O 7 dimers) as revealed by the trimethylsilylation method. Infrared (IR) spectra show a very broad absorption band centered at about 935 cm -1 . Another characteristic feature is the presence of~2.5 wt% H 2 O as shown by thermogravimetry (TG) coupled with IR spectroscopy. As this water is bound mostly as hydroxyl to Ca, we refer to this new cementitious material as calcium-oxidehydroxide-silicate (C-CH-S). Calorimetric measurements point to a very high hydraulic reactivity which is beyond that for typical C 2 S materials. The influence of the type of grinding on the thermal behavior of a-C 2 SH upon its transformation into water-free Ca 2 SiO 4 modifications is discussed.

A biosensor is described for the detection of triazine and phenylurea herbicides in drinking water by kinetic measurements of endogenous chlorophyll fluorescence in isolated chloroplasts from higher plants. The pocket-size device uses a diode laser for simultaneous excitation of sample and reference channels, and photodiodes for detection of the emitted light. The biological material can be supplied as a freeze-dried powder, stable for 21 days at room temperature, for 6 weeks at 4 ( degrees )C or for at least 9 months at -20 ( degrees )C. The detection of 0.1 microg/l of a single herbicide, as required by European Community legislation on drinking water quality, can be achieved without prior extraction of the sample.

Comparison of wood pyrolysis kinetic data derived from thermogravimetric experiments by model-fitting and model-free methods,