Undergraduate Research Experience Publications

 

The Undergraduate Research Experience provides community college students with an opportunity to join a lab and help support a faculty mentor with a research project. In some cases, URE participants make a valuable contribution to the project, and are added as co-authors when the work is published. 

 

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The following published articles include contributions from URE participants. Authors' names have been boldened to indicate their participation in the Undergraduate Research Experience. 

 

STRUCTURE–PHOTOCHEMICAL FUNCTION RELATIONSHIPS IN THE PHOTOBASICITY OF AROMATIC HETEROCYCLES CONTAINING MULTIPLE RING NITROGEN ATOMS

Sophya F. Alamudun, Kyle Tanovitz,  Lanette Espinosa, April Fajardo, John Galvan, and Andrew S. Petit*
The Journal of Physical Chemistry A, December 29, 2020

 

Abstract

Photobases are compounds that become more basic when promoted to an excited electronic state. Previous experimental and computational studies have demonstrated that several quinoline and quinoline-derived compounds are strong photobases (pK a * > 14). Moreover, the strength of photobasicity was shown to depend strongly on the identity and position of the substituent group(s), with the strongest photobases having multiple electron-donating substituents on a fused benzene ring as opposed to the ring containing the photobasic nitrogen atom. These electron-donating substituents build up electron density on one side of the molecule that shifts onto the nitrogen-containing ring in the electronic transition. This shift in electron density produces an increase in negative charge on the ring nitrogen atom responsible for the photobasicity. In this paper, we expand on our previous investigation to study the effect of an additional ring nitrogen atom on photobasicity in aromatic heterocycles. In particular, we consider how the thermodynamic driving force for excited-state protonation can be tuned by changing the relative placement of the ring nitrogen atoms and varying the position and number of electron-donating substituents. In the set of 112 molecules screened, we identified 42 strong photobases with generally comparable pK a * but lower vertical excitation energies than the quinoline derivatives with only a single ring nitrogen atom. We additionally explored photobasicity in substituted azaindole and carboline derivatives, identifying 76 strongly photobasic compounds with pK a * as large as 22.6 out of the 155 compounds that we considered. Overall, this work provides new insights into the design principles necessary to develop next-generation photocatalysts that employ photobasicity.

Full Article: Structure-Photochemical ...
  
 

Quantifying the non-equilibrium activity of an active colloid

Sarah Eldeen, Ryan Muoio,  Paris Blaisdell-Pijuan, Ngoc La, Mauricio Gomez, Alex Vidal, and Wylie Ahmed*
Soft Matter, April 22, 2020

 

Abstract

Active matter systems exhibit rich emergent behavior due to constant injection and dissipation of energy at the level of individual agents. Since these systems are far from equilibrium, their dynamics and energetics cannot be understood using the framework of equilibrium statistical mechanics. Recent developments in stochastic thermodynamics extend classical concepts of work, heat, and energy dissipation to fluctuating non-equilibrium systems. We use recent advances in experiment and theory to study the non-thermal dissipation of individual light-activated self-propelled colloidal particles. We focus on characterizing the transition from thermal to non-thermal fluctuations and show that energy dissipation rates on the order of ∼k B T s −1 are measurable from finite time series data.

Full Article: Quantifying the non-equilibrium ...
  

 

DESIGN, MICROWAVE‐ASSISTED SYNTHESIS, BIOLOGICAL EVALUATION AND MOLECULAR MODELING STUDIES OF 4‐PHENYLTHIAZOLES AS POTENT FATTY ACID AMIDE HYDROLASE INHIBITORS

Stephanie R. Wilt, Mark Rodriguez, Thanh N. H. Le, Emily V. Baltodano, Adrian Salas, Stevan Pecic*
Chemical Biology & Drug Design, February 15, 2020

Abstract

Endocannabinoids, anandamide (AEA) and 2‐arachidonoylglycerol (2‐AG), are endogenous lipids that activate cannabinoid receptors. Activation of these receptors produces anti‐inflammatory and analgesic effects. Fatty acid amide hydrolase (FAAH) is a membrane enzyme that hydrolases endocannabinoids; thus, inhibition of FAAH represents an attractive approach to develop new therapeutics for treating inflammation and pain. Previously, potent rat FAAH inhibitors containing 2‐naphthyl‐ and 4‐phenylthiazole scaffolds were identified, but up to the present time, very little structure–activity relationship studies have been performed on these moieties. We designed and synthesized several analogs containing these structural motifs and evaluated their inhibition potencies against human FAAH enzyme. In addition, we built and validated a homology model of human FAAH enzyme and performed docking experiments. We identified several inhibitors in the low nanomolar range and calculated their ADME predicted values. These FAAH inhibitors represent promising drug candidates for future preclinical in vivo studies. 

Full Article: Design, Microwave-Assisted ...
 

Nonstatistical Dissociation Dynamics of Nitroaromatic Chromophores

K. Jacob Blackshaw,   Belinda I. Ortega,   Naa-Kwarley Quartey,   Wade E. Fritzeen,   Robert T. Korb,   Annalise K. Ajmani,   Lehman Montgomery,   Marcus Marracci,   Geronimo Gudino Vanegas ,  John Galvan,   Zach Sarvas,  Andrew S. Petit, *   and Nathanael M. Kidwell *

The Journal of Physical Chemistry A, April 30, 2019

Abstract

Organic carbon in the atmosphere is emitted from biogenic and anthropogenic sources and plays a key role in atmospheric chemistry, air quality, and climate. Recent studies have identified several of the major nitroaromatic chromophores embedded in organic “brown carbon” (BrC) aerosols. Indeed, nitroaromatic chromophores are responsible for the enhanced solar absorption of BrC aerosols, extending into the near UV (300−400 nm) and visible regions. Furthermore, BrC chromophores serve as temporary reservoirs of important oxidizing intermediates including hydroxyl (OH) and nitric oxide (NO) radicals that are released upon electronic excitation. The present work represents the first study of the 355 nm photolysis of known BrC chromophores ortho-nitrophenol and 2-nitroresorcinol, as well as the prototypical nitroaromatic, nitrobenzene. Experiments are carried out in a pulsed supersonic jet expansion with velocity map imaging of NO X2Π (ν′′ = 0, J′′) fragments to report on the photodissociation dynamics. The total kinetic energy release (TKER) distributions and the NO X2Π (ν′′ = 0, J′′) product state distributions deviate significantly from Prior simulations, indicating that energy is partitioned nonstatistically following dissociation. Experiments are conducted in tandem with complementary calculations using multireference Møller−Plesset second-order perturbation theory (MRMPT2) for stationary points obtained by using multiconfiguration self-consistent field (MCSCF) with an aug-cc-pVDZ basis on the ground and lowest energy triplet electronic states. Furthermore, insights into the partitioning of energy upon photodissociation are achieved by using relaxed scans at the MCSCF/aug-cc-pVDZ level of theory. As a whole, the results suggest that upon excitation to S1, all three nitroaromatics share a common overall mechanism for NO production involving isomerization of the nitro group, nonradiative relaxation to S0, and dissociation to form rotationally hot NO.

Full Article: Nonstatistical Dissociation ...
  

DOS attack mitigation strategies on sdn controller

Yun Tian*, Vincent Tran, Mutalifu Kuerban
IEEE Annual Computing and Communications Workshop and Conference (CCWC), March 14, 2019

 

Abstract

Software-Defined Networking (SDN) introduces centralized control logic, and separates the data plane from the control plane. Hence, SDN makes it easier for network engineers to monitor traffic, diagnose threats, and insert or change security policies. However, it also creates security challenges that did not exist before, such as controller security. In this paper, we analyze the effect of DOS attacks on the SDN controller and propose two approaches, FlowSec and Blackbox, to mitigate DOS attacks. FlowSec is a strategy to mitigate an attack on the controller bandwidth by setting a limit on the number of packets that can be sent to the controller per second. Blackbox defines and keeps track of threat levels, detects, and responds to different aggressive attacks in real-time basis. The experiments show that both approaches work well on preventing DOS attacks.

Full Article: DOS Attack ...
 

Published URE participants

Photo of Adrian

Adrian Salas

URE19 Participant

Cypress College

PI: Dr. Stevan Pecic

Chemistry & Biochemistry 

April's Photo

April Fajardo

URE 19 Participant

Santa Ana College 

PI: Dr. Andrew Petit

Chemistry & Biochemistry  

 

Photo of Adrian

emily Baltodano

URE19 Participant

Santiago Canyon College 

PI: Dr. Stevan Pecic

Chemistry & Biochemistry

 

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Geronimo Gudino Vanegas

URE 18 Participant

Fullerton College 

PI: Dr. Andrew Petit

Chemistry & Biochemistry 

 

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Ngoc La

URE 17 Participant

Golden West College 

PI: Dr. Wylie Ahmed

Physics 

 

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Vincent Tran

URE17 Participant

Orange Coast College

PI: Dr. Yun Tian

Computer Science 

 

 

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Zachary Sarvas

URE17 Participant

Santiago Canyon College

PI: Dr. Andrew Petit

Chemistry & Biochemistry