(559g) Illustrative and Easy Topics for Undergraduate Thesis, and Their Influence on Students to Pursue Graduate Studies

The insertion of undergraduate students in scientific research and academic work is significantly enhanced through the following activities: 1) engaging in summer research stays, 2) undertaking an undergraduate thesis, 3) having the opportunity to be included as co - authors in publications, memories, proceedings, as well as 4) forging relations with students and professors of other universities. All of the aforementioned tend to encourage students to pursue graduate studies, which is absolutely necessary for the formation of high level human resources. During more than fifteen years I have promoted these activities in my university and I can state that due those facts, more than 18 undergraduate students have graduated under my supervision since 2006. Currently, some of them are working in the industry, while five of them are doctors, six are masters, and others are currently graduate students at universities in Canada, USA, Germany and Mexico.

A crucial aspect that favors students be attracted by scientific research, is to offer them executable thesis with relatively easy topics and guaranteed success, such that they can realize the importance of focusing on the details, while applying the theory in the experimental work, but most importantly, so that their scientific curiosity is awakened. If professors include students in complicated thesis topics, such that they are very likely to fail, instead of generating enthusiasm, the failure, frustration, and other complications, will disappoint them and move them away from science, in some cases, even resulting in quitting the thesis project. More important aspects that contribute to the success in the elaboration of the undergraduate thesis are the good communication between the student and advisor, to have available all the facilities to do the thesis, to take to the students to local and domestic conferences and to give them enough attention.

It is very important to take advantage of graduate thesis details, gaps and even unexplained inconsistencies, specifically those that can be solved by undergraduate students. The following are some examples of undergraduate thesis completed under my supervision that have lead my students to pursue graduate studies.

1.- “Study of irradiance field, energy balance, phenol degradation and kinetic modeling of the photocatalytic reactor Photo CREC Water II”.

In this case, the topic was water purification, specifically phenol degradation using photocatalysis in an annular reactor operating in batch mode in recirculation, the Photo CREC Water II, with catalyst in aqueous suspension is illuminated by a UV lamp to activate the catalyst. Samples of the aqueous suspension are taken and analyzed in the HPLC, TOC and UV-Vis to monitor the model compound and intermediates. As a result a complicated reaction mechanism and network is developed in this process.

One of the most important contribution of this thesis was the measurement of temperature profiles during the time of the experiments, 1) when the water was just in recirculation with the lamp turned off, 2) then turned on, and finally 3) with the phenol degradation. This information was used to perform the energy balance for the photocatalytic process taking place during the experiments. The earlier temperature measurements, allowed calculating the heat added to the water due to pumping, by using the equation Q =mcpDT. Then, by use of the temperature profiles with the lamp turned on, the heat added to the water due to the effect of both pumping and lamp irradiance was accounted, and the energy absorbed due to the lamp emission was calculated, subtracting the heat determined when lamp was turned off. Part of this energy is known to activate the catalyst, to achieve chemical reaction, while some is going to be delivered as heat to the water due to both the reactions  exothermic nature and inefficiencies arising from charge recombination during the photoelectric effect. Then, the heat calculated using the later temperature profiles, i.e. when the phenol degradation was carried out, allowed to calculate energy consumption for photocatalyst activation while properly subtracting all other relevant effects.

In this way, by use of simple temperature measurements, several problems are posed to the students: 1) the calculation of the energy to activate the catalyst, 2) the calculation of the enthalpies of the reaction and formation of the free radical OH, 3) approximation of the irradiance field in the reaction annular section, 4) the number of active sites estimation, as well as 5) proposal of the reaction network and mechanism, with its respective kinetic and adsorption parameter estimation. Skills and notions are developed through the project, such as usage of Math Lab, to face the challenge of reproducibility of experimental results or to know the apparatus detection limits.

These challenges wake up their scientific curiosity. The involved students were very enthusiastic during the elaboration of their thesis and I am sure, due to this, they now are graduate students. Once they gathered intermediate and model compound concentration profiles, they immediately realize there is a need to propose a logical structure that relates them, i.e. a reaction network. Additionally, the reaction network indicates them that parameter estimation 

comes next, to determine whether model hypotheses are rejected or validated, and refine through an iterative process a model that arises from both experiments and adventuring to propose new ideas based on solid application of organic chemistry, mathematics, physics and scientific research principles in chemical engineering.

Inasmuch as they know that different catalysts lead to different results, they feel the need to understand the nature of the materials, to characterize them, and they get eventually the ability to handle and operate the pieces of equipment, the interpretation of results, among many other things. In summary we are taking advantage of the details of graduate thesis to structure undergraduate thesis.

2.- Impact of different boundary conditions in the angular momentum of the molecules inside a spinning cylinder.

The angular momentum of water inside a rotating cylinder is analyzed for several cases where different boundary conditions are applied. In the first case the cylinder is spinning with water inside, as a result a parabolic surface profile is generated. In the second case the cylinder is fixed, with a central bar rotating. As expected the surface profile has changed, due the different boundary conditions.

 In both cases, it is necessary to analyze the three components of the Navier Stokes equations (momentum equations), and to solve the resulting equations, once the appropriate terms are discarded. From the solutions of these equations, the surface profile equation is deducted. The theoretical results are evaluated y compared with the experimental ones, obtained through photographs of the devices in rotation. In this way the student understand the utility of the mathematical modeling, the importance of the correct deduction of the mathematical models, and how they can allow the prediction of the behavior of the physical system, avoiding experimentation, if the model is already validated.

3.- Non stationary axial temperature profiles from heat conduction in a cylindrical bar.

A cylindrical bar is warmed up in one end and the heat is transmitted axially through the bar by conduction, the experiments are performed for both an insulated and a non-insulated bar, while the other end is exposed to the environment.

The bar has holes in the axial, angular and radial directions, such that it is possible to place thermocouples and measure temperature profiles for all directions. The corresponding mathematical models are solved and the theoretical results are then compared with the experimental profiles. Again, as in former cases, the importance of mathematical modeling, and the acquired notion that, if the model is correctly deducted, heat transfer predictions will avoid unnecessary experimentation. This work can be extended in several ways , such as 1) using a heat source to account for fed heat, 2) putting two bars of different material in series, to verify the continuity boundary condition in the interphase between materials, among others possibilities.

There are of course more examples. So far, all the involved students are doctors, masters, and the elaboration of these theses gave them the scientific curiosity, but more importantly, because they liked the scientific research and academic activities. It is evident that the presented examples are simple enough for undergraduate level studies and the achieved success was one of the reasons why these students are now graduate students and and/or active and highly motivated scientists.