The freshwater microalgae species Chlorella kessleri and Chlorella vulgaris, and the marine microalgae species Nannochloropsis oculata were cultivated in urban wastewater. The freshwater species demonstrated the possibility of growing in urban wastewater reaching high biomass production and nutrient removal when cultured in batch mode using a flat-panel airlift photobioreactor. Both microalgae species reached high biomass dry weights, 2.70 ± 0.08 g/L and 2.91 ± 0.02 g/L respectively, accompanied by nitrogen concentration reduction around 96% and 95%, and a phosphorous concentration reduction around 99% and 98% respectively. N. oculata was able to uptake nutrients from wastewater to grow but with less efficiency, indicating the need of microalgae acclimation or process optimisation to achieve high nutrient removals. During C. kessleri and C. vulgaris cultivation, the nitrogen consumption led to a progressive N-starvation process which increased the microalgae potential for biofuels production; both species produced 346 ± 3 mL CH 4 /g VS and 415 ± 2 mL CH 4 /g VS during anaerobic digestion, and 7.4 ± 0.2 g Biodiesel /100 g VS and 11.3 ± 0.1 g Biodiesel /100 g VS respectively.

Nannochloropsis has emerged as a promising alga for biodiesel production. However, the genus consists of 6 species and hundreds of strains making strain selection a challenge. Furthermore, oil productivity is instrumental to economic viability of any algal strain for industrial production, which is dependent on growth rate and oil content. In most cases, these two parameters have been studied independently. Thus, the goal of this study is to provide a combined method for evaluating strain performance in specially designed photobioreactors together with an in-depth lipidomic analyses. The nine strains of Nannochloropsis tested showed considerable variations in productivity and lipidomics highlighting the importance of strain selection. Finally, Nannochloropsis gaditana CCMP527 and Nannochloropsis salina CCMP537 emerged as the two most promising strains, with an oil content of 37 and 27 dry wt% after 11-day nitrogen starvation, respectively, resulting in TAG productivity of 13×10(-3) and 18×10(-3) kg m(-3) d(-1), respectively.

Strain selection is one of the primary hurdles facing cost-effective microalgal biodiesel production. Indeed, the strain used affects both upstream and downstream biodiesel production processes. This study presents a screening procedure that considers the most significant criteria in microalgal biodiesel production including TAG production and wet extraction and recovery of TAGs. Fourteen freshwater and seawater strains were investigated. Large variation was observed between the strains in all the screening criteria. The overall screening procedure ultimately led to the identification of Parachlorella kessleri UTEX2229 and Nannochloropsis gaditana CCMP527 as the best freshwater and seawater strains, respectively. They featured the largest areal TAG productivity equal to 2.7×10(-3) and 2.3×10(-3)kgm(-2)d(-1), respectively. These two strains also displayed encouraging cell fragility in a high pressure bead milling process with 69% and 98% cell disruption at 1750bar making them remarkable strains for TAG extraction in wet environment.

This study aims to investigate the triacylglycerol (TAG) productivity of Parachlorella kessleri grown under continuous illumination and to investigate its metabolism in simulated day/night cycles in order to estimate the feasibility of a large-scale production in outdoor solar photobioreactors. The strain was chosen for its ability to accumulate large amounts of triacylglycerol during nitrogen starvation. Several protocols of nitrogen starvation were tested in continuous illumination as well as in simulated day/night cycles. Sudden and progressive nitrogen starvation conditions have enhanced the TAG concentration and productivity of P. kessleri reaching up to 48 dry wt% and 4.4 × 10 −3 kg m −2 day −1 , respectively. Microalgal cell metabolism was significantly affected by the day/night illumination cycles. The energy-rich compounds (TAGs and carbohydrates) were accumulated by P. kessleri during the photoperiods and partly consumed during the dark to sustain the microalgae vitality. This TAG oxidation ultimately led to a 26% decrease in TAG productivity in cultures exposed to day/night cycles compared to ones exposed to continuous illumination of equal 24-h average photon flux density. The results can dictate the optimal time for harvesting cells for recovering the largest amount of TAGs.

This study aims to elucidate the role of light absorption rate and nitrate concentration on triacylglycerol (TAG) productivity and cellular TAG accumulation in nitrogen limited Parachlorella kessleri cultures grown in chemostat mode. In batch operated nitrogen starved cultures the cells accumulate large amounts of TAGs at the expense of biomass growth leading to severe decrease in cell division rate prompting eventual cell death. In PBRs operated in continuous mode cell multiplication can persist in nitrogen limited conditions with simultaneous TAG accumulation. P. kessleri cultures were grown in a flat-plate PBR with constant dilution rate of 0.01 1/h and feed-medium nitrate concentration ranging from 1 to 16 mM. The steady-state biomass, pigment, carbohydrate, protein, total lipid, and TAG concentrations as well as the spectral absorption and scattering cross-sections of the microalgae were measured for each culture. These were used to estimate the specific mean rate of photon absorption (MRPA) in the PBR. Maximum areal TAG productivity of 2.6 g/m 2 ⋅day was obtained for the culture grown with nitrate concentration equal to 3.65 mM and a mean rate of photon absorption equal to 17,700 μmol hν /kg X A s. TAG productivity and cellular TAG accumulation varied with the nitrate concentration in the feed medium and MRPA. Finally, our results show that TAG productivity can be further increased by optimizing the mean rate of photon absorption through adjusting culture dilution rate and feed-medium nitrate concentration.

this study explores the effect of using brainstorming strategies in teaching science on improve creative thinking for sixth grade students in Isa town primary school. More specifically, this paper focuses on students' creative thinking skill, There are a lots of ways directed to development of creative thinking is the most important way of brainstorming being tested in the field of education on the many educational materials and proven effective in the development of the creative capabilities of students, such as Collado study (Collado 1992), Sanfilippo (Sanfilippo 1993) , this study comes to know the effect of using the method of brainstorming in the teaching of science on the development of creative thinking for students in the sixth grade primary in kingdom of Bahrain. The population of research is 60 students (two classes). Data were collecting after doing a two test (pre test and post test), quantity data were collected. From this research, some differences have been found in students' the brainstorming strategies have effective of students' creative thinking skills and we found this results from significant differences for experimental group.

In this paper, we analyze the security of a self-recovery fragile watermarking scheme proposed by C. Wang et al. The scheme is designed to control images integrity by locating the tampered areas and then recover the tampered zones. An attack against C. Wang et al.'s scheme is demonstrated, and we were able to manipulate the watermarked images without being detected by the extraction scheme. The theoretical and experimental results show that the proposed scheme is not secure against attacks.