jhussaini's blog

Isopentyl acetate was synthesized in a 35.31% yield from isopentyl alcohol, acetic acid and concentrated sulfuric acid. The mixture of reactants was observed to have a putrid smell whilst the final product had a smell similar to that of bananas. There was also change in color from scarlet reactants to a brown product. These qualitative observations signal the occurrence of a chemical change. The identity and purity of final product was analyzed using IR spectroscopy. The IR spectrum of the final product showed peaks that were characteristic of an ester. A broad peak at 2960 cm^-1 shows the presence of an sp³ hybridized C-H bond. This type of bond is usually seen between 3300 and 2700 cm^-1. There is another large peak on the IR spectrum at 1743 cm^-1 which indicates a C=O bond or a carbonyl. This type of bond is usually seen between 1780 and 1650 cm^-1. These two peaks on their own could indicate the presence of a carboxylic acid or an ester, both of which have sp³ hybridized bonds and a carbonyl group. However, the lack of a broad peak between 3650 and 3200 cm^-1 shows that the final product is not a carboxylic acid because it does not contain a hydroxyl group. In addition, the IR spectrum of the final product shows a large peak at 1244 cm^-1, which is in the fingerprint region between 1250 and 1050 cm^-1. This large peak indicates a C-O bond, which is characteristic of an ester.

Into a 5 mL round-bottomed flask, isopentyl alcohol (1.2 mL), acetic acid (0.744 mL), 4 drops of concentrated sulfuric acid and 3 boiling chips were added. The solution was refluxed for 15 minute intervals for a total of 3 intervals or 45 minutes. After each interval, the organic phase was removed from the side arm of the flask and added to the solution. After refluxing, the contents of the round-bottomed flask were transferred to a centrifuge tube. The centrifuge tube was extracted with water (1 mL). This extraction process was repeated with sodium bicarbonate (1 mL) and sodium chloride (1 mL). 5 spheres of calcium chloride were added into a vial containing the organic phase. The mixture was transferred to a new vial and analyzed by infrared spectroscopy.

Trimyristin was isolated from nutmeg through the processes of micro-scale filtration and recrystallization, and was then reacted to produce myristic acid. The trimyristin was recrystallized twice to collect it in the highest purity. The percent yield of the second recrystallization (83.29%) is higher than percent yield of the first recrystallization (71.88%). The higher percent yield shows that a greater proportion of impurities were removed after the second recrystallization. The melting points of the trimyristin after the first and second recrystallizations also indicate the difference in purity between them. The melting point of trimyristin after the first recrystallization is 52-55 ºC, which is lower than its theoretical melting point of 56-57 ºC. A lower melting point indicates that there are more impurities in the compound. In contrast, the melting point of the trimyristin after the second recrystallization is 56-57 ºC. This value matches the theoretical melting point of trimyristin and it is higher than the previous melting point, both of which indicate its high purity. The melting point of the trimyristin that was twice recrystallized also has a narrower melting point range of 1 ºC, which demonstrates the homogeneity and purity of the substance. The melting point of myristic acid was observed at 53-54 ºC. The purity of the myristic acid is shown by the narrow melting point range. The theoretical melting point of myristic acid is 54.4 ºC. The myristic acid formed in this experiment is pure because it is close to this value.

Trimyristin was isolated from nutmeg, and produced myristic acid. The trimyristin was recrystallized two times to collect it in the highest purity. The percent yield of the second recrystallization (83.29%) is higher than percent yield of the first recrystallization (71.88%). The melting points of the trimyristin after the first and second recrystallizations indicate the difference in purity between them. The melting point of trimyristin after the first recrystallization is 52-55 ºC, which is lower than the theoretical melting point of 56-57 ºC. A lower melting point indicates that there's are more impurities in the compound. The melting point of the trimyristin that was twice recrystallized also has a more narrow melting point range of 1 ºC, which demonstrates the homogeneity and purity of the substance. The melting point of myristic acid was observed at 53-54 ºC. The purity of the myristic acid is shown by the narrow melting point range. The theoretical melting point of myristic acid is 54.4 ºC. The myristic acid formed in this experiment is pure because it is close to this value. 

The internal anatomy of the insect Drosophila Melanogaster bears a few similarities and many differences with mammal anatomy. While the mammalian circulatory system is closed, the circulatory system of Drosophila is open. This means that the blood is not confined to blood vessels, but rather it bathes the internal organs and tissues. Another interesting fact is that the blood of Drosophila does not contain red blood cells. This stands in contrast to mammals, which have hemogloben in their red blood cells to carry oxygen to tissues throughout the body. Instead of relying on the circulatory system for oxygen transport, Drosophila use a tracheal system. Air diffuses through small openings called spiracles, and enters a branch-like structure called the trachea which delivers oxygen to all of the cells. 

Gastrotrichs live in a diverse range of habitats. They can be found in freshwater, marine, and a few semi-terrestrial environments, though they are more abundant in freshwater and marine environments.  In semi-terrestrial environments, they live in a film of water surrounded by grains of soil. Because they are so small, they usually live in interstitial spaces between particles of sediment. They are also a part of the benthic community, and are usually attached to underwater plants or submerged objects, which makes them sessile organisms. They have adhesive tubes all over their body allowing them to attach to surfaces. They also have a short life cycle that can span from 3-21 days depending on the species.

The weaknesses of this study involve the mortality rate of their test subjects. I was shocked to hear in class that somewhere around 25% of the mice died during testing from seizures. This makes sense considering they are just activating a whole bunch of neurons with a simple injection. It makes me wonder whether this could be effecting the behavior of the mice that did survive the experiment. For example, could their fear response with and without CNO be a natural anxiety developed from brain damage from the experiment? Secondly, the results from Fig 1D are somewhat concerning as it takes about an hour for the mice to respond to CNO which could mess with results. Additionally, the results rarely ever revealed over a 50% freezing which are nor very strong results.  Despite that, because of their control experiments, and logical experimental outline, the results are still valid, just not as strong as we could hope for.

When marine mammals dive into deep, high pressurized waters, they experience an increase in dissolved nitrogen gas in their bloodstreams. The dissolved gas poses a threat because if the divers ascend too fast, they experience a phenomenon known as the “bends,” whereby gas bubbles form inside the body and increase the risk of contracting decompression sickness. Fortunately, marine mammals have a special lung architecture that creates two different pulmonary regions to combat high-pressure depths. They have a compressible chest that limits the amount of nitrogen gas that can be absorbed. The authors of the review article suggest that the physiology of diving mammals is poorly understood, and that there are other cardiorespiratory mechanisms that provide a better explanation for their ability to dive deeply. The results of the paper showed that many marine mammals can withstand high levels of nitrogen gas that would normally cause decompression sickness 50% of the time. The authors also hypothesized that parasympathetic stimulation helps limit lung perfusion, which is a necessary for diving to great depths. They propose that high amounts of stress can interfere with this process and might explain the failure of a normal dive response. Overall, these findings are significant because they offer a new perspective on the physiological and respiratory adaptations that enable cetaceans to dive at great depths. 

When marine mammals dive into deep, high pressured waters, they experience an increase in dissolved nitrogen gas in their bloodstreams. The dissolved gas poses a threat because if divers ascend too fast, it can lead to a phenomenon known as the “bends,” whereby gas bubbles form inside the body and can potentially cause decompression sickness. Fortunately, marine mammals have special lung architecture that creates two different pulmonary regions to combat high-pressure depths. They have a compressible chest that limits the amount of nitrogen gas that can be absorbed. The authors of the review article suggest that the physiology of diving mammals is poorly understand, and that there are more cardiorespiratory mechanisms that provide a better explanation for their ability to dive deeply. The results of the paper showed that many marine mammals can withstand levels of nitrogen gas that would normally cause decompression sickness 50% of the time. The authors also hypothesized that parasympathetic stimulation helps limit lung perfusion, which is a necessary for diving to great depths. They propose that stress can interfere with this process which might explain failure of a normal dive response. Overall, these findings are significant because they offer a new perspective on the physiological and respiratory adaptations that enable cetaceans to dive at great depths. 

The authors first cloned melanopsin cDNA in rat cells to show that the protein sequence is nearly identical to that of mice. Then they generated specific antibodies targeting melanopsin to show the subset of cells that contained the protein. Tau-lacZ targeting shows the projections of melanopsin positive cells to the SCN and other regions of the brain. Lastly, they used a combination of immunofluorescence and Lucifer Yellow to show that intrinsically photosensitive RGC’s were melanopsin positive. Figure 3 shows that the authors targeted the tau-lacZ gene locus RGC’s and used immunofluorescence in mice. The structure of melanopsin positive cells was similar to that in rats. X-gal labeling not only showed retinal labeling of axons, cell bodies and dendrites, but it also showed B-galactosidase activity in parts of the brain such as the SCN, the olivary pretectal nucleus, the dorsal lateral geniculate, and other parts of the brain. This finding suggested that melanopsin positive cells are involved with processing information that is relayed to the brain.