sfairfield's blog

          The first case study Pearce offers in Honduras was the one I found most disturbing. Berta Caceres an indigenous environmental activist who opposed dams, mines, and other development projects, was assassinated in her home in 2016 by armed intruders after years of threats to her life. It is believed that her murder was retaliation for her organizing against the Agua Zarca dam project on the Gualcarque River in village of Rio Blanco funded Desarrollos Energéticos SA. Associates of the energy company and special forces from the Honduran government are thought to be responsible. The idea of a government being so corrupt and beholden to private interests that they participate in the assassination of one of their own citizens is frightening and infuriating. Other activists had also faced violence, according to Pearce, including being shot at by government soldiers during protests and even attacked with a machete by pro-dam families who claim activists are hindering economic development. This situation and the situation in Israel in which soldiers callously interfere with Palestinians obtaining clean water were a saddening reminder of how commonplace state violence is around the world.

I found Pearce’s description of the conflicting hydrological requirements of dams interesting and the risks brought on by these contradictions to be interesting. That dams like those on the Yellow River need to both remain full enough to feed irrigation systems, provide urban water, and generate hydroelectricity, as well as maintain low enough to catch floodwaters while catching floods require them to maintain low water levels, despite the obvious incompatibility of those two goals, leads to potentially dangerous situations. Pearce described the Banqiao Dam disaster in the Henan Province in central China as an example of one such circumstance. The dam had been experiencing a typhoon that raised the water levels and became overwhelmed by the addition of water from an upstream dam burst, until it gave way to 400,000 acre feet of water forming a wave 7 miles wide and 20 feet high. The death total, excluding the aftermath, was nearly 26,000 people. Pearce states that over ten times more were killed by the ensuing chaos and famine. The descriptions of such a devastating incident, and the danger of such incidents happening again, was both compelling and deeply concerning.

I found Pearce’s description of the conflicting hydrological requirements of dams interesting and the risks brought on by these contradictions to be interesting. That dams like those on the Yellow River need to both remain full enough to feed irrigation systems, provide urban water, and generate hydroelectricity, as well as maintain low enough to catch floodwaters while catching floods require them to maintain low water levels, despite the obvious incompatibility of those two goals, leads to potentially dangerous situations. Pearce described the Banqiao Dam disaster in the Henan Province in central China as an example of one such circumstance. The dam had been experiencing a typhoon that raised the water levels and became overwhelmed by the addition of water from an upstream dam burst, until it gave way to 400,000 acre feet of water forming a wave 7 miles wide and 20 feet high. The death total, excluding the aftermath, was nearly 26,000 people. Pearce states that over ten times more were killed by the ensuing chaos and famine. The descriptions of such a devastating incident, and the danger of such incidents happening again, was both compelling and deeply concerning.

          In this experiment, 3-methylbutyl acetate was synthesized via esterification using acetic acid and 3-methyl-1-butanol as reagents and sulfuric acid as the catalyst. The odor of acetic acid resembled that of vinegar, while the odor of 3-methyl-1-butanol resembled an artificial sour apple smell. The odor of the product, 3-methylbutyl acetate, resembled an artificial banana smell. This indicates that the product was successfully synthesized, because 3-methylbutyl acetate is known informally as banana oil. The percent yield of the product was 84.42%. The low yield could have been a result of transfer loss from some product remaining in the reflux column. The product was also identified via IR spectroscopy. The IR displayed an alkyl C-H stretch at 2959.90 cm-1 and a C=O stretch at 1741.80 cm-1, as well as no large absorptions above 3000 cm-1, indicating that there are no O-H containing impurities. These experimental data are consistent with the known  IR spectrum of a typical alkyl ester, which is characterized by an alkyl C-H stretch that is just to the right of 3000 cm-1 and a C=O stretch that is at about 1750 cm-1. This supports the conclusion that 3-methylbutyl acetate was successfully synthesized.

           For the work-up, the cooled contents of the rb flask were transferred into a centrifuge tube containing water (1.0 mL, 56.0 mmol). The layers were mixed thoroughly, allowed to resettle, and then the lower aqueous layer was removed into a beaker marked for waste. Saturated aqueous sodium bicarbonate (1.0 mL, 5.4 mmol) was added, the layers were mixed thoroughly the lower aqueous layer was removed into waste.This process was repeated. Saturated aqueous sodium chloride (1.0 mL, 7.9 mmol) was added, the layers were mixed thoroughly, and the lower aqueous layer was removed to waste. The organic layer was transferred into a vial, and five spheres of anhydrous CaCl2 were added to the mixture and swirled until no clumping occurred, then left to stand for about five minutes. The liquid was transferred to a dry, tared vial. The odor was noted, the final mass was measured and recorded,  and IR spectroscopy was performed. 

          Acetic acid (0.774 mL, 13 mmol) and 3-methyl-1-butanol (1.2 mL, 11 mmol) were placed into a 5 mL round-bottomed (rb) flask.  The odor of each compound was noted. Four drops of concentrated sulfuric acid were added to the rb flask and the contents were mixed thoroughly. Boiling chips were added and the flask was placed within a reflux apparatus above the hot plate. The contents of the rb flask were heated to a gentle boil such that vapors condensed about one third of the way up the reflux condenser. This resulted in two phases of liquid collecting in the side arm, which were an upper organic phase and a lower water phase. After the reaction refluxed for fifteen minutes, the apparatus was removed from the heat and tipped back so that most of the upper phase in the side arm went back into the reaction flask, and then lowered back into the hot plate. This process was repeated twice more, so that the mixture refluxed for forty-five minutes total. At the end of the third and final reflux period, the apparatus was cooled completely for fifteen minutes. Once cooled, the entire contents of the side-arm were emptied into the rb flask.

         The bio-archeological dataset from Radovic et al. comprises cranial pathology measurements and cranial age assessment for 113 individuals from four Mesolithic-Neolithic sites in the Danube Gorges, Serbia. One of the characteristics the data quantify is the surface wear of left mandibular molars. The occlusal surface of each molar is divided into four quadrants. Each quadrant received a surface wear score, in which low values indicate no or little wear and high values indicate substantial tooth wear. We are interested in whether there is a difference in the mean tooth wear of the first quadrant of molar one and the first quadrant of molar three. The null hypothesis is that there is no difference in the mean tooth wear between the first quadrant of molar one and the first quadrant of molar three, and the alternative hypothesis is there is a difference in the mean tooth wear between the first quadrant of molar one and the first quadrant of molar three because first molars erupt much earlier than third molars and thus experience many more years of wear. The method of analysis chosen was a two-sample t-test. The t-value was 8.7324, meaning the difference between the group mean values is large relative to the amount of variation in the groups. The p-value is 1.042e-15, meaning there is a less than 5% chance of getting the observed result, or a more extreme result, if the null hypothesis is true, which means the data does not support the null hypothesis. In conclusion, there is a significant difference in the mean surface wear of the first quadrants of molars one and three.

          The bio-archeological dataset from Radovic et al. comprises cranial pathology data and cranial age assessment for 113 individuals from four Mesolithic-Neolithic sites in the Danube Gorges, Serbia. The data quantify the surface wear of left mandibular molars. The occlusal surface of each molar is divided into four quadrants. Each quadrant received a surface wear score. Low values indicate no or little wear and high values indicate substantial tooth wear. We are interested in whether there is a difference in the mean tooth wear of the first quadrant of molar one and three. The null hypothesis is that there is no difference in the mean tooth wear between the first quadrant of molar one and the first quadrant of molar three, and the alternative hypothesis is there is a difference in the mean tooth wear between the first quadrant of molar one and the first quadrant of molar three because first molars develop much earlier than third molars and thus experience many more years of wear. The t-value is 8.7324, meaning the difference between the group mean values is large relative to the amount of variation in the groups. The degrees of freedom are 198, meaning the sample size is 200. The p-value is 1.042e-15, meaning there is a less than 5% chance of getting the observed result, or a more extreme result, if the null hypothesis is true, which means the data does not support the null hypothesis. In conclusion, there is a significant difference in the mean surface wear of the first quadrants of molars one and three.

          In this experiment, trimyristin was isolated via extraction from nutmeg using tert-butyl methyl ether. The product was recrystallized using acetone, and hydrolysis was performed to obtain myristic acid. The percent yield of crude trimyristin from nutmeg was 49.20 %. The melting point of the crude was 51 - 55 °C. The percent recovery for the first recrystallization of trimyristin was 39.68 %, and the melting point for this sample was 53 - 56 °C. The percent recovery for the second recrystallization of trimyristin was 65.64 %, and the melting point for this sample was 54 - 56 °C. The relatively low percent recoveries from the recrystallizations could have been due to the use of excess acetone. The known melting point for trimyristin is 56 - 57 °C, which is similar to, but slightly higher than, the experimental melting points, possibly due to the presence of impurities. The range of melting points became narrower from the crude sample, to the first recrystallized sample, to the second recrystallized sample, most likely due to the decreasing amount of impurities following each recrystallization process. The percent yield of myristic acid from trimyristin was 65.14 %, and the melting point was 51 - 52 °C. The known melting point of myristic acid is 54.4 °C, which is similar to, but slightly higher than, the experimental melting point, possibly due to remaining impurities in the sample.

          The first recrystallization of the crude trimyristin was performed using enough acetone to dissolve the crude product inside the Erlenmeyer flask. The mixture was cooled to room temperature for five minutes and left in the ice bath for 15 minutes, rinsed with additional acetone while collected via vacuum filtration. A weight and melting point was obtained. Hydrolysis was performed. A sample of the recrystallized trimyristin (0.06 g, 0.083 mmol) was transferred to a clean RB flask, along with 6 M NaOH (2.0 mL, 106.508 mmol), 95% ethanol (2.0 mL, 34.252 mmol), and two boiling chips. The solution was refluxed gently on the hot plate for 45 minutes. During hydrolysis, the remaining recrystallized trimyristin sample was recrystallized a second time in the same manner as before, except the warm solution was allowed to cool to room temperature for 10 minutes before cooling in ice for another 10 minutes. The weight and melting point were obtained. After the hydrolysis had proceeded for 45 minutes, the flask was allowed to cool to room temperature, after which the contents were poured into a 50 mL beaker containing water (8.0 mL, 444.0 mmol). HCl (2.0 mL, 65.826 mmol) was added dropwise while stirring until myristic acid precipitated. The beaker was cooled in ice water for 10 minutes, with stirring, and the resulting solid was collected via vacuum filtration, rinsing with water. A weight and melting point were obtained.