Is it PAO-GAO competition or metabolic shift in EBPR system? Evidence from an experimental study

Reduced EBPR performance in full and bench-scale EBPR studies was linked to the proliferation of GAOs but often time with the lack of any evidence. In this study, a detailed enzymatic study was coupled with batch tests and electron microscopy results for a realistic explanation. The results eliminated the possibility of population shift from PAO to GAO or other non-PAO due to the short batch test period provided which would not allow a population shift and further justified with the electron microscopy results. The results indicate that glycogen serves not only as source of reducing power for PHA production but also serves as an alternative energy source when the poly-P pool of the PAOs is depleted. Slow generation of ATP via glycolytic pathway at 5 degrees C cannot satisfy energy requirements of EBPR cells to complete several cell functions including acetate uptake and PHA storage. However, the glycolytic pathway is efficiently operable at warm temperatures (> 20 degrees C). The reduced performance of enhanced EBPR facilities operated at warm temperature may not be a result of GAO proliferation; instead it may be related the efficient use of the glycolytic pathway by PAOs which results in more glycogen storage and less P uptake, thereby reducing the EBPR performance.     

Synergetic effects of temperature and magnetic field on the aragonite and calcite growth

The effects of temperature and magnetic field on aragonite and calcite growth were investigated in a stirred-tank crystallizer, using the constant-composition technique. At room temperature without magnetization, the calcite seeds grew but the aragonite did not. When the growth rates of the aragonite and calcite seeds were measured in the presence of a magnetic field at temperatures above room temperature, the synergetic effects were significant but with differing effects on the different seeds. The cluster-transformation mechanism was used to explain the growth rate data. Finally, the aragonite growth rate data were compared with data obtained in a fluidized bed.     

A neuronal ryanodine receptor mediates light-induced phase delays of the circadian clock

Circadian clocks are complex biochemical systems that cycle with a period of approximately 24 hours. They integrate temporal information regarding phasing of the solar cycle, and adjust their phase so as to synchronize an organism's internal state to the local environmental day and night. Nocturnal light is the dominant regulator of this entrainment. In mammals, information about nocturnal light is transmitted by glutamate released from retinal projections to the circadian clock in the suprachiasmatic nucleus of the hypothalamus. Clock resetting requires the activation of ionotropic glutamate receptors, which mediate Ca2+ influx. The response induced by such activation depends on the clock's temporal state: during early night it delays the clock phase, whereas in late night the clock phase is advanced. To investigate this differential response, we sought signalling elements that contribute solely to phase delay. We analysed intracellular calcium-channel ryanodine receptors, which mediate coupled Ca2+ signalling. Depletion of intracellular Ca2+ stores during early night blocked the effects of glutamate. Activators of ryanodine receptors induced phase resetting only in early night; inhibitors selectively blocked delays induced by light and glutamate. These findings implicate the release of intracellular Ca2+ through ryanodine receptors in the light-induced phase delay of the circadian clock restricted to the early night.     

Determination of partition coefficients and aqueous solubilities by reverse phase chromatography—I: Theory and background

Water solubilities and octanol/water partition coefficients are widely used to predict partitioning and bioconcentration phenomena for hydrophobic organic pollutants in aqueous systems. This paper is the first in a two part series describing the application of high performance reverse phase liquid chromatography (HPRPLC) for indirect estimation of these two physicochemical parameters to facilitate environmental fate and transport predictions for organic compounds. In the first part, thermodynamic factors which control partitioning processes, water solubilities, and reverse phase retention behavior are discussed, and models for interlinking these three properties are summarized. The second part presents the results of aqueous solubility and octanol/water partition coefficient predictions for a number of organic contaminants from measurements of their HPRPLC behavior, and compares the modeling capabilities of some of the theoretical partitioning/solubility equations developed in the first paper.