Some species in genus Dunaliella are unique in their remarkable abilities to accumulate large numbers of beta-carotene and thrive in media containing a wide range of NaCl concentrations ranging from about 0.05 M to saturation (around 5.5 M). The algae contain no rigid polysaccharide cell wall and thus have been found to be able to rapidly change their volume and shape in response to changes in the extracellular hypo- or hyper-osmotic pressure. In osmotic adjustment, the osmoregulatory response of Dunaliella functions to maintain osmotic balance at high salinities by synthesis and varying the intracellular concentration of glycerol. In this review, we describe the osmotic response process of Dunaliella under salinity stress, including the changes of cell volume, intracellular ions concentration, intracellular glycerol concentration, and the expression of some salt-induced genes. Some specific proteins and enzymes can be induced by different salinities in osmotic response process. In addition, we introduce the exogenous expression of salt-related genes of Dunaliella salina in plants and microorganisms for the purpose of confirming the functions of related genes, proteins, and enzymes. The aim of this review is to emphasize the importance of the studies on the mechanisms of osmotic adjustments of Dunaliella in order to develop its unique osmotic characteristics. It is prospected that future research should pay attention to the specific signal transduction pathway and the mechanism of osmoregulation, and to improve the salt tolerance of higher plants by using salt-tolerant genes of Dunaliella.
As olive oil is the main source of calories in the Mediterranean diet, a large number of studies have been carried out to characterize its role in various diseases and exploitation for the prevention and treatment of hypertension, carcinogenesis, diabetes, atherosclerosis, and other diseases. As one of the major polyphenols present in virgin olive oil, hydroxytyrosol shows a variety of pharmacological activities such as antioxidant properties, anticancer, anti-inflammatory, and neuroprotective activities, and beneficial effects on the cardiovascular system, which show its potentiality for the development of dietary supplements. In the future, more attention should be paid to its action mechanism in vivo and synergistic effect. Further research will be performed to provide the theoretical basis for hydroxytyrosol and its derivatives use as health supplements.
Closing the anthropogenic carbon cycle is one important strategy to combat climate change, and requires the chemistry to effectively combine CO2 capture with its conversion. Here, we propose a novel in situ CO2 utilization concept, calcium-looping reforming of methane, to realize the capture and conversion of CO2 in one integrated chemical process. This process couples the calcium-looping CO2 capture and the CH4 dry reforming reactions in the CaO-Ni bifunctional sorbent-catalyst, where the CO2 captured by CaO is reduced in situ by CH4 to CO, a reaction catalyzed by catalyzed by the adjacent metallic Ni. The process coupling scheme exhibits excellent decarbonation kinetics by exploiting Le Chatelier’s principle to shift reaction equilibrium through continuous conversion of CO2, and results in an energy consumption 22% lower than that of conventional CH4 dry reforming for CO2 utilization. The proposed CO2 utilization concept offers a promising option to recycle carbon directly at large CO2 stationary sources in an energy-efficient manner.
Original PaperOptimum extraction Process of polyphenols from the bark of Phyllanthus emblica L. based on the response surface methodology Phyllanthus emblica L. is an economic plant used in Chinese medicine for the treatment of various diseases. The bark of P. emblica is rich in polyphenols and its extractions have shown strong antioxidative and radical scavenging activity. Response surface methodology (RSM) was used to assess the optimal extraction of polyphenols from P. emblica bark. Various extraction parameters including ethanol concentration, extraction time, temperature, solid -liquid ratio, and extraction times were chosen to identify their effects on polyphenols extraction. Among these parameters, extraction times and solvent concentration were found to have significant effect on polyphenols extraction. RSM was applied to obtain the optimal combination of solvent concentration, extraction time, temperature, and extraction time for maximum rate of extraction. The most suitable condition for the extraction of polyphenols was at ethanol concentration 75%, extraction time 25 min, extraction temperature 458C, and extraction times 3. At these optimal extraction parameters, the maximum extraction of polyphenols obtained experimentally was found to be very close to its predicted value. The extraction rate of polyphenols was 19.78% at the optimum conditions. The mathematical model developed was found to fit with the experimental data of polyphenols extraction.
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