Physical Sciences and Mathematics Commons^™

Zyrtec, Regan Ford

Natural Sciences Student Research Presentations

No abstract provided.

Provera, Sarah Asklund

Natural Sciences Student Research Presentations

No abstract provided.

Caffeine And You, Maxwell Young

Natural Sciences Student Research Presentations

No abstract provided.

Ethanol From The Field To The Pump, Cameron Heiser

Natural Sciences Student Research Presentations

This poster describes the use of dry mill and wet mill processes to produce ethanol.

Ketogenic Diets, Erin Wolfe

Natural Sciences Student Research Presentations

No abstract provided.

Fluoride And Your Teeth: How Fluoride In Dental Products Protects Your Teeth From Cavities, Jacob Dickey

Natural Sciences Student Research Presentations

This poster examines the use and effectiveness of fluorine to prevent cavities.

Diabetic Ketoacidosis, Thanaporn Chittiphalungsri

Natural Sciences Student Research Presentations

This poster describes the causes, diagnosis, and treatment of diabetic ketoacidosis.

The Many Pharmaceutical Discoveries Of Gertrude B. Elion, Alayna Bonse

Natural Sciences Student Research Presentations

This poster discusses the contributions of Gertrude B. Elion to pharmaceutical science.

Polymers Used In Medicine: Common Types And Benefits Of Drug Delivery Systems, Camille Andrews

Natural Sciences Student Research Presentations

This poster describes the common types and benefits of drug delivery systems.

The First Example Of Amine-Induced Reversal Of Diastereoselectivity In Acylation Of Some Trans-2-Substituted Cyclohexanols, Andrey V. Samoshin, Jasper Visser, Matthew Curtis, Vyacheslav V. Samoshin, Andreas H. Franz

College of the Pacific Faculty Articles

The reaction between racemic acyl chlorides and racemic trans-2-substituted-cyclohexanols proceeds diastereoselectively. We found for the first time that addition of a tertiary amine not only accelerates the acylation, but for some substituents leads to complete inversion of diastereoselectivity. These observations have been rationalized in terms of a possible stereoselective intramolecular assistance by the substituent group during the acylation of the neighboring hydroxyl group.

Gap Detection For Genome-Scale Constraint-Based Models, J. Paul Brooks, William P. Burns, Stephen S. Fong, Chris M. Gowen, Seth B. Roberts

Statistical Sciences and Operations Research Publications

Constraint-based metabolic models are currently the most comprehensive system-wide models of cellular metabolism. Several challenges arise when building an in silico constraint-based model of an organism that need to be addressed before flux balance analysis (FBA) can be applied for simulations. An algorithm called FBA-Gap is presented here that aids the construction of a working model based on plausible modifications to a given list of reactions that are known to occur in the organism. When applied to a working model, the algorithm gives a hypothesis concerning a minimal medium for sustaining the cell in culture. The utility of the algorithm …

Size And Phase Control Of Cobalt-Carbide Nanoparticles Using Oh- And Cl- Anions In A Polyol Process, Zachary J. Huba, Everett E. Carpenter

Chemistry Publications

Exchange coupled cobalt–carbide nanocomposites and single-phase Co₂C nanoparticles were synthesized using the polyol process. Hydroxide and chloride anions were used to controlcarbide phase and particle shape. Synthesized Co _x C nanocomposites exhibited average diameters around 300 nm. Co _x C nanocomposites synthesized at 0.25 M [OH⁻] and [Cl⁻] formed clusters of capped nanorods, whereas synthesis at 0.37 M [OH⁻] and [Cl⁻] produced clusters of long blade-like particles. For single-phase Co₂C, an [OH⁻] and [Cl⁻] of 0.71 M was used and produced clusters of ellipsoidal …

Adsorption Of Oxygen-Containing Functional Groups On Free And Supported Graphene Using Point Contact, Qian Wang, D. X. Ye, Y. Kawazoe, Puru Jena

Physics Publications

First-principles electronic structure calculations based on spin-polarized density functional theory were carried out to study the adsorption of oxygen-containing functional groups -OH, -CHO, and -COOH on a two-dimensional (2D) infinite graphene sheet without edge states and defects. We find that the energy gain of adsorption can be significantly improved when the graphene sheet is supported via a point contact, a prototype for graphene sheet supported by catalysts, nanoparticles or nanopillars, or a surface with steps, edges, adatoms, or defects. This was modeled by placing a single atom of Fe, Co, and Ni under the graphene surface. Thus supported graphene not …

Two-Step Thermal Quenching Of Photoluminescence In Zn-Doped Gan, Michael A. Reshchikov

Physics Publications

We observed tunable two-step thermal quenching of photoluminescence in high-resistivity Zn-doped GaN. The characteristic temperatures of the first and second steps increase with increasing excitation intensity. The effect is explained within a phenomenological model involving shallow donors, nonradiative deep donors, and two types of acceptors.

Tuning Magnetic Properties Of Graphene Nanoribbons With Topological Line Defects: From Antiferromagnetic To Ferromagnetic, Min Kan, Jian Zhou, Qiang Sun, Qiang Wang, Yoshiyuki Kawazoe, Puru Jena

Physics Publications

Zigzag-edged graphene nanoribbons are antiferromagnetic in cross-edge coupling and unsuitable for spintronics applications. Two new strategies of tuning antiferromagnetism (AFM) to ferromagnetism (FM) in graphene nanoribbons are introduced through topological line defects composed of pentagonal and octagonal rings, and their ability to induce magnetic transition is probed by using density functional theory. The resulting exchange energy is found to be large enough for ferromagnetism to be observed at room temperature. Both strategies are experimentally feasible, and the results suggest that defect engineering may provide a novel path to manipulate the magnetic properties of graphene nanoribbons.

Determination Of The Absolute Internal Quantum Efficiency Of Photoluminescence In Gan Co-Doped With Si And Zn, M. A. Reshchikov, M. Foussekis, J. D. Mcnamara, A. Behrends, A. Bakin, A. Waag

Physics Publications

The optical properties of high-quality GaN co-doped with silicon and zinc are investigated by using temperature-dependent continuous-wave and time-resolved photoluminescence measurements. The blue luminescence band is related to the Zn_Ga acceptor in GaN:Si,Zn, which exhibits an exceptionally high absolute internal quantum efficiency (IQE). An IQE above 90% was calculated for several samples having different concentrations of Zn. Accurate and reliable values of the IQE were obtained by using several approaches based on rate equations. The concentrations of the Zn_Ga acceptors and free electrons were also estimated from the photoluminescence measurements.

Electrical Transition Of (3,3) Carbon Nanotube On Patterned Hydrogen Terminated Si(001)-2 X 1 Driven By Electric Field, Bikash C. Gupta, Shyamal Konar, Puru Jena

Physics Publications

Structure, energetics, and electrical properties of (3,3) carbon nanotube(CNT) supported on patterned hydrogen terminated Si(001): 2 × 1 surface are studied using density functional theory. Our investigation reveals that an otherwise metallic (3,3) CNT when supported becomes semiconducting with a band gap of ≈0.5 eV due to its strong interaction with the surface. During adsorption, Si-C bonds form at the interface and charges transfer from Si surface to CNT. The Si-C bonds at the interface are partially covalent and partially ionic in nature. Under the application of an external electric field, the bandgap of the supported CNT reduces to zero, …

Magnetism Of Electrons In Atoms And Superatoms, Victor Medel, J. Ulises Reveles, Shiv N. Khanna

Physics Publications

The quantum states of electrons in small symmetric metallic clusters are grouped into shells similar to the electronic shells in free atoms, leading to the conceptual basis for defining superatoms. The filling of the electronic shells in clusters, however, do not follow Hund's rule and usually result in non-magnetic species. It is shown that by embedding a transition metal in group II atoms, one can stabilize superatoms with unpaired electronic supershells. We demonstrate this intriguing effect through electronic structure studies of MnSr_n (n = 6-12) clusters within first principles generalized gradient calculations. The studies identify an unusually stable magnetic …

Ferromagnetism In Li Doped Zno Nanoparticles: The Role Of Interstitial Li, Saif Ullah Awan, S. K. Hasanain, Massimo F. Bertino, G. Hassnain Jaffari

Physics Publications

ZnO nanoparticles doped with Li (Zn_1−yLi_yO, y ≤ 0.1) have been investigated with emphasis on the correlation between their magnetic, electronic, and structural properties. In particular, defects such as interstitial Li and Zn atoms, substitutional Li atoms, and oxygen vacancies have been identified by X-ray photoelectron spectroscopy(XPS) and their respective roles in stabilization of the magnetic moment are discussed. X-ray diffraction(XRD) and XPS give clear evidence of Li presence at both substitutional and interstitial sites. XPS studies further show that the amount of substitutional Li defects (Li_zn) and interstitial Li defects (Li_i) …

Structural Changes Of Pd-13 Upon Charging And Oxidation/Reduction, J. Ulises Reveles, A. M. Köster, P. Calaminici, S. N. Khanna

Physics Publications

First-principle generalized gradient corrected density functional calculations have been performed to study the stability of cationic and anionic Pd₁₃ ^+/−, and neutral Pd₁₃O₂ clusters. It is found that while cationic Pd₁₃ ⁺ favors a C _s geometry similar to the neutral Pd₁₃, both anionic Pd₁₃ ⁻ and neutral Pd₁₃O₂ favor a compact ∼I _h structure. A detailed analysis of the electronic structure shows that the stabilization of the delocalized 1P and 2P cluster orbitals, and the hybridization of the 1D orbitals with the oxygen atomic p orbitals …

Evolution Of Superhalogen Properties In Ptcln Clusters, Jorly Joseph, Kalpataru Pradhan, Purusottam Jena, Haopeng Wang, Xinxing Zhang, Yeon Jae Ko, Kit H. Bowen Jr.

Physics Publications

We have systematically calculated the ground state geometries, relative stability, electronic structure, and spectroscopic properties of PtCl _n (n = 1–7) clusters. The bonding in these clusters is dominated by covalent interaction. In neutral clusters, chlorine atoms are chemically bound to Pt up to n = 5. However, in neutral PtCl₆ and PtCl₇ clusters, two of the chlorine atoms bind molecularly while the remaining bind as individual atoms. In the negative ions, this happens only in the case of PtCl₇ cluster. The geometries of both neutral and anionic clusters can be considered as fragments of an …

Aspirin But Not Ibuprofen Use Is Associated With Reduced Risk Of Prostate Cancer: A Plco Study, F. M. Shebl, L. C. Sakoda, A. Black, J. Koziol, G. L. Andriole, R. Grubb, T. R. Church, D. Chia, Cindy Zhou, +8 Additional Authors

GW Biostatistics Center

Background:

Although most epidemiological studies suggest that non-steroidal anti-inflammatory drug use is inversely associated with prostate cancer risk, the magnitude and specificity of this association remain unclear.

Methods:

We examined self-reported aspirin and ibuprofen use in relation to prostate cancer risk among 29 450 men ages 55–74 who were initially screened for prostate cancer from 1993 to 2001 in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Men were followed from their first screening exam until 31 December 2009, during which 3575 cases of prostate cancer were identified.

Results:

After adjusting for potential confounders, the hazard ratios (HRs) of …

Oxidative Stress And Down Syndrome: A Route Toward Alzheimer-Like Dementia, Marzia Perluigi, D. Allan Butterfield

Chemistry Faculty Publications

Down syndrome (DS) is one of the most frequent genetic abnormalities characterized by multiple pathological phenotypes. Indeed, currently life expectancy and quality of life for DS patients have improved, although with increasing age pathological dysfunctions are exacerbated and intellectual disability may lead to the development of Alzheimer's type dementia (AD). The neuropathology of DS is complex and includes the development of AD by middle age, altered free radical metabolism, and impaired mitochondrial function, both of which contribute to neuronal degeneration. Understanding the molecular basis that drives the development of AD is an intense field of research. Our laboratories are interested …

Multicomponent Cubic Oxide Exsolution In Synthetic Basalts: Temperature Dependence And Implications For Magnetic Properties, Julie A. Bowles, Lisa Tatsumi-Petrochilos, Julie E. Hammer, Stefanie A. Brachfeld

Geosciences Faculty Articles

Although the compositional unmixing of cubic-structured iron oxides has profound effects on the magnetic properties of rocks that contain them, a basic understanding of the kinetics and thermodynamics of this process has not been achieved in experimental studies due to sluggish reaction rates in binary oxide phases. Exploiting the fact that many natural Fe-oxides contain multiple additional cations, including Ti, Mg and Al, we perform novel “forward” laboratory experiments in which cubic-cubic phase exsolution proceeds from initially homogeneous multicomponent oxides. A variety of Fe-Ti-Mg-Al cubic iron oxides were nucleated and grown in synthetic, multicomponent basalt under different ƒO2 environments, and …

Determination Of Copper In Aqueous Solutions By Chelation With Diethyldithiocarbamate, Caitlin Allison

Summer Community of Scholars Posters (RCEU and HCR Combined Programs)

No abstract provided.

"The Objective Of This Experiment Is To Try To Reach A Coupling Efficiency Of 1% Through A Small Pinhole, Using An Led As A Source...", Gregory E. Drubka

Summer Community of Scholars Posters (RCEU and HCR Combined Programs)

No abstract provided.

Natural Antiparasitic Coumarins: An In Silico Study, William R. Erwin

Summer Community of Scholars Posters (RCEU and HCR Combined Programs)

No abstract provided.

A Chemical Ecological Investigation Of The Allelophatic Potential Of Lamium Amplexcaule And Lamiun Purpureum, Chelsea D. Jones, Katherine E. Woods

Summer Community of Scholars Posters (RCEU and HCR Combined Programs)

No abstract provided.

Measuring Antioxidant Properties Through Frap, Xanthine Oxidase, And Orac Assays, Christina Lee

Summer Community of Scholars Posters (RCEU and HCR Combined Programs)

No abstract provided.

Analysis Of Critical Point Phenomena In Binary Liquid Systems, Carl Pattison

Summer Community of Scholars Posters (RCEU and HCR Combined Programs)

No abstract provided.