Ashley+Guo

Ashley's Article Summaries

1. A group of Portuguese scientists developed a method to enhance the process of grape seed oil extraction using certain enzymes. They used various concentrations, pH, temperatures, time allowed for reaction, and particle size. The mixture of enzymes consisted of cellulase, protease, xylanase, and pectinase. The seeds were separated from the pulp of the grape’s fruit and washed, sieved and milled. The small grape seed particles were then separated in a sifter to determine various particle sizes. In each separate trial, ten grams of the grape seed particles were used, and the ratio of the enzyme mixture to the amount of seeds was kept constant at 4mL of enzyme mixture per gram of grape seeds. The reaction was carried out at a 200 rpm stirring at a constant temperature and was stopped by freezing the solution with liquid nitrogen. Water was then removed by freeze-drying the suspension. After each trial, the amount of oil extracted was determined after the solvent was allowed to evaporate. Additional measures were taken to ensure that no water remained in the solution. By using the enzymatic method, the scientists found that the extraction of grape seed oil yielded 106% more grape seed oil than samples without enzyme treatment. The scientists provided the method of best yield, which was carried out at a pH of 4, temperature of 40 degrees Celsius, particle diameter of 1.0 to 1.4 mm, with a predetermined concentration for a period of 120 hours. Through this experiment, we see that enzymatic treatment has the potential to greatly increase the yields of extracting grape seed oil. However, more research can be done to assess the practicality of the method, taking into account previous trials that did not have high yields and the expenses of using enzymes as an alternative to industrial methods.

Passos, Claudia. "Enhancement of grape seed oil extraction using a cell wall degrading enzyme cocktail." __Food Chemistry__ 115(2009): 48-53.

2. Scientists in Thailand carried out experiments involving co-combustion of rice husks and coal. Rice husks would be attained from the rice-milling process, and would be particularly abundant in Asian countries. The scientists used a combustor that combined concepts from both a cyclonic combustor and a fluidized-bed combustor. Coal and rice husk entered the combustor through separate feeders which could be controlled to regulate the rate of feeding. The combustor was fired with rice husks inside it, and then additional rice husks were fed into the combustor, followed by bituminous coal. The three sources of air blowing into the combustor were kept at constant velocities. Throughout the process of combustion, the scientists observed temperatures and gas emissions. Each trial had duration of six hours, and it took 1.5 hours to reach a steady state of combustion, after which gas emissions were monitored every 2 minutes for a period of 2 hours. The combustion efficiency was determined by analyzing ash collected every 15 minutes from an outlet of the cyclonic component, and a tube was inserted into the center of the combustor to measure gas concentrations. In conclusion, the trials confirmed that co-firing in the cyclonic fluidized-bed combustor was possible. Combustion efficiency above 97% was easily attainable, but unburned carbon (found in the ash) factored into decreasing efficiency. The emissions of nitrogen oxides ranged from 260 to 416 ppm, but could be fixed by decreasing the size of the coal particles or lowering the combustor bed’s temperature. Sulfur dioxide ranged from 10 to 180 ppm, and was much lower than Thailand’s regulations of 236 ppm. This experiment gives us insight into mixing byproducts such as rice husks with coal and co-firing them, but there are still improvements to be made in abiding by safety regulations.

Madhiyanon, Thanid. "Co-combustion of rice husk with coal in a cyclonic fluidized-bed combustor (ψ-FBC)." Fuel88(2008): 132-138.

3. Familial high cholesterol is, for the most part, caused by mutations in the receptor gene for LDL. A group of scientists tested High Resolution Melting for potential as a sensitive and efficient method to screen for LDLR mutations. During the “melting” of DNA, the temperature gradually increases, and the two strands of DNA detach. The results are monitored by fluorescent dyes that allow real-time observations. The scientists used DNA samples previously identified as containing LDLR mutations by denaturing high pressure liquid chromatography and sequencing methods. Out of the 60 samples, four had problematic mutations. Out of the remaining 56, 54 of the mutations were detected, and the other 2 had unclear results. Unlike the high pressure liquid chromatography, the melting analysis was not sensitive enough every single time, as can be seen by having the two unclear results. However, the cost and speed of analysis using melting analysis are much more efficient in comparison to using liquid chromatography. The melting analysis doesn’t require solvents, pumps, injectors, and methodical challenges that come with using the liquid chromatography method, and the complete cost of the melting analysis and sequencing is half of using the high pressure liquid chromatography screen. Also, High Resolution Melting is significantly faster than the liquid chromatography, working at a rate 100 times faster than the chromatography. Even though melting analysis has certain disadvantages, we can take advantage of its advantages, including speed, cost, and the smaller number of complications.

Laurie, Andrew. "Evaluation of high-resolution melting analysis for screening the LDL receptor gene." Clinical Biochemistry 42(2008): 528-535.

4. Nanoparticles have become increasingly used for medicinal purposes. Scientists exposed mice to silver-25 nanoparticles and studied its effects on the mouse brain to observe if the nanoparticles posed any toxic harm to aspects such as gene expression. Adult male mice were administered one of three doses of silver-25 and were observed then discarded after 24 hours. After being treated with the silver nanoparticles, certain genes that promoted diseases were upregulated, including the genes that put the mice at risk for Parkinson's disease, Alzheimer's disase, and Huntington's disase. The silver nanoparticles were found to create high levels of reactive oxygen species (ROS) that would induce oxidative stress that would damage gene expression. The dosage was found not to have a correlation with any damage, as sometimes lower dosages caused more upregulation than higher dosages. Gold nanoparticles have been receiving attention for being potential cancer-drug delivery agents. While gold and silver obviously have different properties, this experiment shows that while nanoparticles may possess beneficial properties as a medium of medicine delivery, they may also pose a risk to subjects by increasing the risk of developing complications due to the changes to gene expression.