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Pla Microsphere Lab Report

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2.3 Fabrication of PLA microsphere
The term “microsphere” refers to small spherical particles having diameters of micrometer ranging from 1–1000 µm. Microspheres is also known as microparticles (Bao et al., 2006). Good microspheres should fulfill these requirements: (1) able to maintain the stability and biological activity of the drug during the encapsulation process, (2) the size is smaller than 250 µm, (3) the amount of drug released should not beyond the specified limit, and (4) must be in the form of pure powder without containing any impurities and form aggregates or coagulant (Jain, 2000).
There are many ways to prepare PLA microspheres including emulsification technique with single or double solvent evaporation system (Bao et al., …show more content…

Surfactants of emulsions are amphiphilic which means it contain both hydrophilic and hydrophobic groups. So when emulsion, the surfactant covers the surface of drops with its hydrophobic part in the drop and its hydrophilic part in the water. Typically, there are four types of surfactants: anionic, cationic, amphoteric and non-ionic. The anionic surfactants such as sodium dodecyl sulphate (SDS) release a negative charge in the aqueous solution. They have a relatively high level of hydrophilicity. Conversely, cationic surfactants such as cetyltrimethyl ammonium bromide (CTAB) release a positive charge in an aqueous solution. On the other hand, in alkali pH, amphoteric surfactants act as anionic while in acid pH, it act as cationic. Non-ionic surfactants such as partially hydrolyzed PVA (polyvinyl alcohol) have no charge (Li et al, 2008). Among four types of surfactants, partially hydrolyzed PVA is most frequent used because it gives the smallest microsheres (Jeffrey et al, 1991). The amount of PVA used may affect microparticles properties. Freitas and coworkers have added 1.3% and 8% of PVA into an aqueous solution and found that both lower and higher concentrations of surfactant results in coagulation of the particles. Hence, these authors suggested to use 3% of PVA as it the most optimum concentration. (Freitas and Marchetti,

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Suppose you need to find the fractional European call and the fractional European put options. Let the Hurst parameter be $H=0.85$, the $\sigma=0,25$, $r=0.10$, $S_{fbm} = 100$, $K = 95$, we have \begin{eqnarray*} d_1^{fBm} & = & \frac{\ln{\frac{S}{K}} + \frac{1}{2}(r( T - t) + \frac{(1)\sigma^2{( T^{2H} - t^{2H})}}{2})}{\sigma{\sqrt{T^{2H} - t^{2H}}}}\\ & = & \frac{\ln(\frac{105}{100}) + (0.10(0.25 -0) + \frac{(1){0.25^2}{0.25^{2(0.85)} - (1)0.25^{2(0.85)}}}{2}}{(0.25){\sqrt{0.25^{2(0.85)} - 0}})} \end{eqnarray*} we obtain $d^{fBm}_1= 1.0558$. We find in the normal distribution that $N(1.0558)= 0.8544$ and $N(-1.0558) = 0.1456.$

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Our hypothesis was partially correct, the property changing substances did have the weakest coherency with the lowest drop counts of 23(carbonated), and 14(soap), and pure water did have the strongest bond. What we also found was the the salt also dampened the liquid’s ability to hold onto a penny in large volumes, as all the different salts had a drop average of 24(28x2 & 16), five less than Tap water’s drop count (30). This led us to conclude that pure water has the strongest bond and that all foreign materials weaken the coherency of water. This evidence has led me to believe that similar substances are attracted and are more coherent towards themselves, in this case the water pieces get separated and generally less connected on a really small level due to the obstruction of foreign objects, this is why the different salts perform better than the huge air bubbles or the slippery properties of soap since the latter is more obstructive and the former dissolves with the water and blocks less. When studying a few other groups’ conclusions and data we did indeed find differences: some groups had differing data where a solution had better coherence than water itself which led to differing conclusions.

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