**CHEMISTRY:**

Lab Report: Analysis of Gold Nanoparticles

Nanoparticles change shape during chemical reactions, and subsequently change color by scattering and absorbing different wavelengths of light. By analyzing the wavelength of light absorbed by gold nanoparticles in a colloid, we determined that nanoparticles’ efficiency per each wavelength can be mapped, that ions can change the shape of nanoparticles that can cause them to reflect and scatter different wavelengths of light. This means that they absorb and scatter different energies, and therefore appear different colors. Changes on the nano scale can make a particle capable of being used in many applications, such as DNA testing for specific diseases.

Lab Report: Analysis of Mercury in Canned vs Fresh Tuna

In this experiment, we analyzed mercury content found in canned tuna provided to us by the laboratory. We then compared our findings to those of our peers who analyzed canned and fresh tuna. The purpose of this experiment was to determine if the mercury content was higher or lower in canned or fresh tuna, and determine if the mercury content in either of these samples poses a threat to the public, by FDA standards. We found that the mercury content in both the canned and fresh tuna was lower than the 1 ppm human limit, but that both exceeded average levels.

**DESIGN ENGINEERING:**

Bionic Wrench: A review of the Bionic Wrench design from Loggerhead Tools

**GENERAL ENGINEERING:**

EA2-final-2005 ; EA2-final-2006

These General Engineering finals were given to us as practice exams so that we could study for our exam. One is from 2005, the other 2006. They cover statics and dynamics. They may be useful for physics students or first year engineering students.

Practice Quizzes for General Engineering / First Year Engineering Students. Topics include Statics, Dynamics, and other basic concepts:

Constitutive laws, force balance, modeling, Euler’s Method, State Equations, springs and dampers, differential equations, friction, momentum, free body diagrams, Kirchoff’s rules, values of dynamic variables, circuit logic problems, analogous mechanical and electrical systems.

Lab Report: EA4 lab 1 – A Quickest Descent Problem

Using Matlab, we will attempt to find values of a that minimize the time it takes for the bead to slide down the wire, and result in a value close to x(t) = ¼ gt^2.

Lab Report: EA4 lab 2 – Adaptive Time Stepping

In this lab we explore the ignition of a combustible mixture including heat loss by numerical simulation. We use the differential equation (1), dy/dt = exp(y) – αy, y(0) = 0, to model this heat loss.

Lab Report: EA4 lab 3 – Natural Frequencies of a Complex Structure

In this lab, we analyze the two systems of a damped and undamped car tire from our textbook, section 3.6. We use the equation: Mx’’ + cx’ + kx = kacos((2πvt)/L) (where m = mass, c = damping constant, k = spring constant, a = starting amplitude, v = velocity, x = height of car above equilib) to calculate the natural frequencies of these structures, and determine the speed at which the car must be going to reach its practical resonant frequency. We use Matlab to prove that the analytical and numerical solutions are nearly identical, if the right timestep is chosen, and that the relative maximums and minimums of the analytical and numerical solutions are identical, and occur at the same times.

Lab Report: EA4 lab 4 – Eigenvalues and Heat Transfer

In this lab, we first answer a set of conceptual questions about eigenvalues regarding a tank (see page 305, Edwards and Penny). After we answer these questions, we proceed to analyze a warm rod with its ends contacting outside material, but insulated along its length. We analyze the temperature of this rod with eigenvectors as the rod cools down to the ambient temperature, T= 0.

Lab Report: EA4 lab 5 – Phase Portraits of Nonlinear Systems

In this lab, we completed four problems: A Predator-prey model, a competition model, a nonlinear pendulum without damping, and a Van der Pol’s oscillator. These problems were mapped by differential equations, which we examined by viewing their phase portraits with the Matlab function pplane

**NOTES: (Including entertaining doodles)**