There is potential for algal-derived biofuel to help alleviate part of the world's dependency on petroleum based fuels. However, research must still be done on strain selection , induction of triacylglycerol (TAG) accumulation, and fundamental algal metabolic studies, along with large-scale culturing techniques, harvesting, and biofuel/biomass processing. Here, we have advanced the knowledge on Scene-desmus sp. strain WC-1 by monitoring growth, pH, and TAG accumulation on a 14:10 light-dark cycle with atmospheric air or 5% CO 2 in air (v/v) aeration. Under ambient aeration, there was a loss of pH-induced TAG accumulation, presumably due to TAG consumption during the lower culture pH observed during dark hours (pH 9.4). Under 5% CO 2 aeration, the growth rate nearly doubled from 0.78 to 1.53 d −1 , but the pH was circumneutral (pH 6.9) and TAG accumulation was minimal. Experiments were also performed with 5% CO 2 during the exponential growth phase, which was then switched to aeration with atmospheric air when nitrate was close to depletion. These tests were run with and without the addition of 50 mM sodium bicarbonate. Cultures without added bicarbonate showed decreased growth rates with the aeration change, but there was no immediate TAG accumulation. The cultures with bicarbonate added immediately ceased cellular replication and rapid TAG accumulation was observed, as monitored by Nile Red fluorescence which has previously been correlated by gas chromatography to cellular TAG levels. Sodium bicarbonate addition (25 mM final concentration) was also tested with the marine diatom Phaeodactylum tricornutum strain Pt-1 and this organism also accumulated TAG.

Algal-derived biodiesel is of particular interest because of several factors including: the potential for a nearcarbon-neutral life cycle, the prospective ability for algae to capture carbon dioxide generated from coal, and algae's high per acre yield potential. Our group and others have shown that in nitrogen limitation, and for a single species of Chlorella, a rise in culture medium pH yields triacylglycerol (TAG) accumulation. To solidify and expand on these triggers, the influence and interaction of pH and nitrogen concentration on lipid production was further investigated on Chlorophyceae Scenedesmus sp. and Coelastrella sp. Growth was monitored optically and TAG accumulation was monitored by Nile red fluorescence and confirmed by gas chromatography. Both organisms grew in all treatments and TAG accumulation was observed by two distinct conditions: high pH and nitrogen limitation. The Scenedesmus sp. was shown to grow and produce lipids to a larger degree in alkaliphilic conditions (pH >9) and was used to further investigate the interplay between TAG accumulation from high pH and/or nitrate depletion. Results given here indicate that TAG accumulation per cell, monitored by Nile red fluorescence, correlates with pH at the time of nitrate depletion.

Microalgae are capable of accumulating high levels of lipids and starch as carbon storage compounds. Investigation into the metabolic activities involved in the synthesis of these compounds has escalated since these compounds can be used as precursors for food and fuel. Here, we detail the results of a comprehensive analysis of Chlamydomonas reinhardtii using high or low inorganic carbon concentrations and speciation between carbon dioxide and bicarbonate, and the effects these have on inducing lipid and starch accumulation during nitrogen depletion. High concentrations of CO(2) (5%; v/v) produced the highest amount of biofuel precursors, transesterified to fatty acid methyl esters, but exhibited rapid accumulation and degradation characteristics. Low CO(2) (0.04%; v/v) caused carbon limitation and minimized triacylglycerol (TAG) and starch accumulation. High bicarbonate caused a cessation of cell cycling and accumulation of both TAG and starch that was more stable than the other experimental conditions. Starch accumulated prior to TAG and then degraded as maximum TAG was reached. This suggests carbon reallocation from starch-based to TAG-based carbon storage.

The purpose of this study was to construct a profile of K-12 music teachers in the United States and develop a model to predict their retention, turnover, and attrition. Responses to the Schools and Staffing Survey from 47,857 K-12 public and private school teachers, including 1,903 music teachers, were analyzed using comparative statistics, factor analysis, logistic regression, and structural equation modeling. Results indicated that music teachers were far more likely than other types of teachers to hold itinerant or part-time positions, and were less likely to receive support for working with special needs students. Music teachers changed teaching positions because of dissatisfaction with workplace conditions and for better teaching assignments. Music teachers left the teaching profession for better salary or benefits, and were generally more satisfied in their new field. Music teachers' perceived level of administrative support had the most prominent influence on both music teacher satisfaction and retention.