Effects of small-scale turbulence on the growth of two diatoms of different size in a phosphorus-limited medium

15 pages, 7 figures, 5 tables, 1 appendix.-- Issue title: "Workshop on Future Directions in Modelling Physical-Biological Interactions (WKFDPBI)"The effect of turbulence on the nutrient flux towards osmotrophic cells is predicted to be size dependent. This should translate into growth. We experimentally followed and modelled the growth of two marine diatoms of different size (Thalassiosira pseudonana, 6 μm in diameter and Coscinodiscus sp., ca. 109 μm in diameter) under still water and turbulent conditions, using a shaker table. Experiments were done with phosphorus-limited cultures and lasted for ca. 5 days. Turbulence enhanced the growth of Coscinodiscus sp. in agreement with theory but not the growth of T. pseudonana, which was actually slightly lower under turbulence. At the end of the experiments there were about 1.7 times as many Coscinodiscus sp. cells in the turbulent treatment than in the still treatment, while for T. pseudonana almost the same cell concentration was found in both conditions. In addition, the Coscinodiscus sp. cells growing under still conditions presented a higher specific alkaline phosphatase activity than those growing in turbulence which indicates a higher need for phosphorus in the still cultures. A simple dynamic model, based on Michaelis Menten nutrient uptake kinetics, needed nearly no optimisation other than using observed initial conditions of phosphate and cell concentrations. The model showed how an increased nutrient flux towards the cells translates non-linearly into cell growth, most likely by affecting the half-saturation constant (KM). However, since Coscinodiscus sp. experienced significant mortality and cells partially settled to the bottom of the containers, unequivocal support for the size-dependent effect of turbulence on nutrient uptake will require further experiments and more sophisticated modelling. The mechanisms to connect an increased nutrient flux towards cells with population growth and whether this process is size dependent are important in parameterizing the effects of turbulence on marine plankton in coupled physical biological modelsThis work was supported by Spanish Projects TURFI (REN2002-01591/MAR) and VARITEC (CTM2004-04442-C02) and by European Union projects MEDEA (MAS3-CT95-0016) and NTAP (EVK3-CT-2000-00022). This is European Land Ocean Interaction Studies contribution 523/40Peer reviewe

Замена электродвигателя ПЭН турбоприводом на Кемеровской ТЭЦ

В данной работе рассматривается возможность замены электродвигателя ПЭН турбоприводом на Кемеровской ТЭЦ, с установкой турбопривода на существующий фундамент. Целью работы является оценка возможности увеличения отпуска электроэнергии от станции в результате уменьшения затрат на собственные нужды и повышение маневренности ТЭЦ.In this paper we consider the possibility of replacing the turbine drive motor PEN to Kemerovo CHP , with the installation of turbine drive on the existing foundation. The aim is to assess the possibility of increasing the supply of electric power from the plant by reducing the costs of their own needs and improving maneuverability CHP