DILUTE ACID HYDROLYSIS OF CELLULOSE UNDER THE INFLUENCE OF ALCHOHOLS IN BATCH AND FIXED-VOLUME FLOW-THROUGH REACTOR VESSELS: AN INVESTIGATION OF CELLULOSE HYDROLYSIS KINETICS
Acid hydrolysis of cellulose mimics a homogeneous, first-order reaction. Increasing the temperature or modifying the pH increases the rate of reaction and enhances glucose yield to 60-70%. However, glucose yields exceeding 90% have been recently produced by using a shrinking-bed flow-through percolation reactor. These results illustrate the heterogeneous nature of the acid hydrolysis reaction and reveal multiple obstacles impeding the degradation of cellulose to glucose, including viscosity, reversibility of hydrogen bonding of released glucose, and a structured layer of water particles. The cause of such resistance apparently lies within the prolific hydrogen bonding of cellulose at the surface and bulk levels. Ethanol was thought to dissolve the hydrogen bond; its hydrophilic and hydrophobic properties were hypothesized to relax the H-bonds hindering hydrolysis and improve glucose yields. Thus, a solution of 5% ethanol and .02wt% flow-through (FT) reactions to set up an alkane gradient. A saturated solution of NaCl was added to the FT reaction to attempt to disrupt the hypothesized structure water layer of cellulose. The effects of ethanol and methanol were minimal, while the propanol solution significantly reduced the rate of reaction, suggesting that the ethanol and methanol solutions played a minimal role at the cellulose surface, while their small size kept them from hindering the reaction. Since NaCl could have affected the movement and delivery of the Hydronium ion to the cellulose interface, NaCl should be tested in a batch reactor to further understand the reaction kinetics. Further experiments should target the effect of various concentrations, flow rates, pressures, and temperatures and should consider a shrinking bed flow-through reactor.
THE SEARCH FOR cAMP-RESPONSE-ELEMENT-BINDING PROTEIN (CREB)
Transcription factors are proteins that bind to DNA along specific chromosomal sits know as promoters or enhancers. In effect, this binding regulates cellular transcription. cAMP-response-element-binding protein (CREB) is one of many such transcription factors that regulate DNA transcription and in turn, protein synthesis. CREB is best known for its influence on complex behaviors such as memory and addiction. While it's binding specificity and functions are well known, CREB is also characterized by its ambiguity. For example, phenotypic expressions of CREB-mediated gene transcription in specific regions of the brain may have entirely opposing effects. Due to this trait, CREB is widely studied in the realm of molecular biology. The first goal of our study was to optimize the detection method of endogenous CREB using Jurkat cells. The second goal was to compare the levels of CREB in HeLa cells and Nicotiana bethamiana plant cells to that of Jurkat cells. After following a standard immunoblot protocol, the results were inconclusive. Future experiments will include repeating the methods through multiple trials for a more accurate representation of the protein extracts, compare CREB across phyla, and develop a system for the production of recombinant CREB.
SYNTHESIS OF AN INTEGRATED BIFUNCTIONAL ANTI-CANCER AGENT
Cancer has proven itself as a formidable obstacle in the scientific research community. While other scientists investigate potential cancer treatments and cures in their respective fields, some organic chemists have synthesized new compounds that show potential in fighting cancer ability by combining characteristics from bioreductive drugs and vascular disrupting agents (VDAs). An integrated compound containing similar structure of both combretastatin A-4 (a vascular disrupting agent), and tirapazamine (a bioreductive drug), was designed as a novel, prospective anti-cancer agent which could potentially be more effective in halting tumor growth. Due to time limitations, the final target molecule has not been synthesized to date. Nevertheless, an intermediate molecule along a synthesis scheme was prepared. Further investigation will focus on converting this intermediate to the target molecule.
PIPER PLATE WASTE STUDY
As the percentage of people in the United States with heart disease and diabetes continues to rise, and the obesity epidemic in the United States becomes more apparent, it becomes clearer that healthy eating habits should begin at a young age. The purpose of this study was to determine whether the menu at the Piper Child Development Center is nutritionally adequate and to make suggestions as to how to improve it, if necessary. The menu was analyzed for a lunch meal on a specific day (when measurements of the amount of food provided and returned by the children would be obtained) and for two weeks (based on estimates of the amount of food the children would eat). The day that children were observed eating, measurements were made of amount of food served, amount of food returned, and the nutritional value of the calculated amount of food eaten using EatRight analysis for children two years old and four years old. The results from the single day analysis showed that the children were underserved in energy, several vitamins and minerals, and consumed too much protein and fat. For further study, a more exact measure of nutrient intake could be obtained for food eaten over a 5 day period and included all of the food served at the center
SYNTHESIS AND TISSUE MODIFICATION TO AID IN MENISCAL INJURIES
Synthesis of compounds to covalently modify tissue surfaces in a spatially-defined manner has been shown to be possible. The use of polymeric adhesives as tissue bonding agents is also possible, but not ideal because of the bulk chemical residue left on the tissue. The desire for a more viable organic bonding agent prompted this research. Past experiments depended on the reactivity of endogenous amine groups. In this work however, a different strategy involving a non-polymeric, low-molecular weight organic crosslinker was explored. Bond-strength testing with a force gauge revealed adhesion that far surpassed previous photochemical or organic compound-mediated bonding. The results of this experiment suggest that low molecular weight organic compounds are viable as organic bonding agents to heal meniscal tears.
COMPLEX PLASMAS: THE PROCESS OF SPLITTING
The new field of complex plasmas has become increasingly important in scientific studies, as they offer new industrial opportunities for innovative mesoscopic material production and modification. It also offers the possibility to study phase transitions in a Coulomb crystal system. In order for complex plasma to form, dust must be suspended airborne against gravity so it can be studied as a crystal. The process of "floating" dust is achieved through the use of plasma, the material phase that follows gas. This next phase is created by forcing gas molecules to split, creating ions and electrons within a reference cell. When the charges are separated, the electrons create a charge in the dust. Having a negative electrode on the bottom surface in the reference cell and applying a negative charge to the dust with the electrons of the gas creates a repelling force and compels the dust to levitate against gravity. Since "like charges repel," the particles remain about the ground. By analyzing these dust particles and changing such variables as voltage, pressure, and power, the effect of two-dimensional splitting can be investigated. Since dust particles act like atoms, but are larger, phase changes can be examined. By either decreasing or increasing the voltage, pressure or power, a change in the crystalline structure of the Coulomb crystal can be observed. Observing the creation of more chains as certain variables are changed could lead to a better understanding of phase changes. A change from solid to liquid and finally to gas, could help further explain the transitions that occur in between these three states of matter. The dusty plasma used in labs could also further explain the details of the formation of planets.
THE MEDICAL APPLICATIONS OF MECHANICAL ENGINEERING
Each day an active person makes countless movements that are made possible, to a large extent, by the human skeletal system. This skeletal system has a complex mechanical design and is composed of biomaterials, amazingly perfected to their task. In order to gain a more complete understanding of the human body, it is crucial that the various mechanical aspects of the skeletal components are studied. These aspects include the properties of bones, bone fracture mechanisms, bone decomposition, meniscal strength and elasticity, meniscal regeneration, and the effects of long-term skeletal implants (such as total hip replacement). These studies have already yielded results which have changed the medical concept of the skeletal system, and will continue to do so as other projects deepen our understanding. I have assisted in all areas of these (ongoing) studies, from setting up machine equipment for the test to preparing samples to running the actual test.
COMPOSITIONAL AND STRUCTURAL ANALYSIS OF MoS2 AND Li DOPED MoS2
ONTOGENETIC VARIATION OF THE AUDITORY STRUCTURE IN THE HISPID COTTON RAT, Sigmodon hispidus
Craig I. White
The study of hearing loss in humans depends on the use of model species for experimentation. One of the most common animals used as models are rats. Due to the generalized nature of their hearing range, however, little research has been done on the middle ear ossicles of rats, focus instead being on the ossicles of more specialized species. This has resulted in a lack of understanding of the mechanisms of hearing in rats, limiting their use as hearing-loss model species. The goal of this study was to describe the auditory structures of the hispid cotton rat (Sigmodon hispidus), a common generalized rodent, with special emphasis on the diversity of ontogenetic patterns in these structures. We selected 30 specimens; 15 male and 15 female, spanning the full body size range of the species that was available in the Baylor University Collection of Vertebrates. We measured 11 cranial and auditory features and used skull length and bulla measurements as ontogenetic indicators. Correlation analyses were then run using measured features against ontogenetic indicators. Two ontogenetic trends were noted: ones that varied significantly with age and ones that did not. Those that varied significantly with age were primarily cranial features, while those that did not were mainly features directly related to hearing (the dimensions of the malleus and stapes). The notable exceptions were the measurements of the incus, whose increase in size perhaps relates to the growth of the bulla. But overall the results suggest that functional hearing is achieved very early in life in this species.
EPIMERIZATION OF AN L-ALANINE DERIVATIVE
Xingyue (Lily) Zhang
Previous research has focused on the stereochemical selectivity in the coupling of L with DL amino acid derivatives, which is a kinetic selectivity. This project examines the thermodynamic selectivity for L-L versus D-L by epimerizing N-acetyl-L-alanine-L-alanine methyl ester in the presence of an acid or base. The goal was to obtain and compare the equilibrium ratio if the diastereomers formed to that of the kinetic ratio obtained previously. We dissolved solid N-acetyl-L-alanine-L-alanine methyl ester and an octadecane internal standard into dichloromethane and added either an acid or base resin catalyst. Gas chromatography (GC) analysis revealed that, with both the acid and base resin catalysts, the diastereomer ratio changed dramatically over a period of three hours. However, the peak for the new diastereomer (L-D or D-L) receded with time, behavior not consistent with the simple equilibration of diastereomers. We found that epimerization was occurring mainly in the injection port. Apparently there was enough acid or base contaminating the GC injection port to cause epimerization, but in an irreproducible manner. Nuclear Magnetic Resonance (NMR) spectroscopy showed that the acid caused a slow change in the NMR spectrum that might have been the L-L to L-D epimerization. Authentic samples of the L-D derivative are being purified now to check this possibility. Another aspect of the project was the purification of other dipeptid derivatives such as N-acetyl-L-phenylalanine-DL-alanine methyl ester, N-acetyl-L-isoleucine-DL-alanine methyl ester, and N-acetyl-L-valine-DL-alanine methyl ester by column chromatography and thin layer chromatography (TLC). Because of time constraints, the epimerization was only performed on the L-alanine-L-alanine derivative.