Friday May 4th – Presentations

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Interfacial Dynamics in Additively Manufactured Polymer Matrix Composites

Kyle J. Johnson, Andrew Abbott, Lutz Wiegart, Jeff Baur, Hilmar Koerner

UES Inc., University of Dayton Research Institute, Brookhaven National Laboratory (NSLS II), Air Force Research Laboratory

10:55 AM
Additive Manufacturing

Additive manufacturing (AM) is pervasive across many disciplines at the Air Force Research Laboratory (AFRL). AFRL is investing in these novel manufacturing processes because of their appeal in rapid prototyping, part reduction and the ability to manufacture complex parts using design and topology optimization. Before AM is robust enough for metals, polymers, ceramics and composite manufacturing, morphology/processing/performance relationships have to be established. The presentation will give a brief overview of the different AM areas that AFRL is working on with focus on AM for polymer matrix composites. The road to road interface in additively manufactured composite parts is crucial for part performance. As an example, weakness and anisotropy at this interface have been key areas of study in the pursuit of more robust additively manufactured parts. Here, the dynamics and morphology at road-to-road interfaces were explored in an epoxy/nanoclay  composite ink using X-Ray photon correlation spectroscopy (XPCS). We observe a time scale associated with equilibrium dynamics, and observe substantially faster dynamics perpendicular to the road-to-road interface than parallel. This anisotropy in dynamics is shown to pass through a maximum both into the recently printed and previously printed road. The behavior is discussed relative to the alignment of the composite particles during shear of the ink through the extrusion head. The ultimate goal of this research is to use the in-situ data to calibrate more conventional techniques that can be implemented within an AM machine and use this to advance close-loop feedback control in AM processes in the future.

Electrospinning of natural and synthetic polymers

Nelly Mateeva, Jamie Hamilton, Brittney Jackson, Christopher Weider

Florida A&M University

09:25 AM
Physical Chemistry

Nanostructured materials with high surface area are of tremendous importance for many industrial applications, such as production of catalysts, sensors, and thermoelectric materials. Electrospinning, a method which applies high voltage to a solution, or melt of a polymeric material, allows for the synthesis of fibers from nano- to micro- size with versatile properties. High surface-to-volume ratio and the availability of functional groups enable post-modification and further processing of the material. Most synthetic polymers are easy to electrospin, however proteins are notoriously difficult to convert to individual, bead-less fibers. The reasons for this are not well understood and we explored the effect of many parameters, such as viscosity, delivery rate, solvent, etc., on the production of nanofibers from egg while lysozyme (HEWL). Our group also created several metal-polymer composite materials that involving transition metals, with possible application in catalysis.

Assessment of potential markers of waste in wetland-treated wastewater

Emily C. Heider and Joseph Welch

University of Central Florida

04:55 PM
Environmental

Wastewater treatment facilities are remarkably effective in the removal of anthropogenic chemical components (e.g. caffeine) in waste. Even so, some compounds are persistent despite treatment with bacterial degradation, UV light, ozonation, and chlorination at the treatment facilities. Effluent from wastewater treatment facilities contains high concentrations of nitrogen (N) and phosphorus (P), yet these can be remediated with secondary water treatment wetlands that use natural processes to remove N and P nutrients and promote the health of natural waterways downstream. The Orlando Easterly Wetland (OEW) is an example such water polishing; this facility receives approximately 15 million gallons of treated wastewater per day, and through plant uptake, sedimentation, precipitation and bacterial denitrification, nutrients in the water are drastically decreased before the outflow to the St. Johns River. This research seeks to quantify sucralose (an artificial sweetener) and uric acid (the product of purine catabolism in animals and humans) at the Orlando Easterly Wetlands (OEW), to determine if these markers of human waste persist through wetland water polishing processes. Additionally, the uric acid in the water was studied to determine if its concentration increased through the excretions of avian, reptilian, and aquatic species.

Drug Discovery Efforts at UNF

Kenneth K. Laali

Department of Chemistry, University of North Florida

02:50 PM
Showcase

Parent curcumin CUR (a natural product constituent in turmeric) has a wide spectrum of biological activity as anti-inflammatory, anti-tumor, antioxidant, and antibacterial agent, but efforts to develop CUR as a therapeutic agent have not met with success due to major drawbacks associated with its low solubility, low bioavailability, and rapid metabolism.

In a quest to find "hit-compounds" inspired by CUR, but with improved physicochemical characteristics for clinical development, we are working on a multi-faceted project that combines synthesis, NMR studies and X-ray analysis with DFT optimizations, computational/docking studies and in-vitro bioassay.  To date several libraries of curcuminoids (over 80 compounds) have been synthesized and characterized, and a significant number have been tested for anti-tumor activity against a host of cancer cell lines. A progress review will be presented.

 

 

 

UPLC-MS/MS analysis of Kratom products and components

Bonnie A. Avery,1 Abhisheak Sharma,1 Alicia G. Lydecker,2 Kavita M. Babu,2 Edward W. Boyer,2 Christopher R. McCurdy3

1Department of Pharmaceutics, University of Florida, Gainesville, FL 32610, Division of Medical Toxicology, 2Department of Emergency Medicine, University of Massachusetts Medical School Worcester, MA 01655 3Department of Medicinal Chemistry, University of Florida, Gainesville, FL 32610

09:25 AM
Analytical Chemistry

Aims: Kratom (Mitragyna speciosa), a plant native to Southeast Asia, has been used for centuries for its stimulant and opium-like effects. Mitragynine and 7- hydroxymitragynine, are the alkaloids thought to be responsible for Kratom's biologic and psychoactive profile, and likely contribute to its problematic use. In this study, we compared the pure isolate to that of an aqueous tea extract of Kratom in pharmacokinetic studies utilizing rats. We also purchased several commercially available Kratom products for analysis looking for evidence of probable adulteration.

Methods: A UPLC-MS/MS method was developed for simultaneous quantification of mitragynine and 7-hydroxymitragynine in methanol extract of commercial Kratom supplements. Rat pharmacokinetic studies were conducted using mitragynine and an equivalent amount of mitragynine in the Kratom tea extract at a dose of 10 mg/kg I.V. and 20 mg/kg P.O.

Results: The bioavailability of mitragynine, when given as tea extract, was 36% compare to the mitragynine having absolute bioavailability of 21%. The Cmax and AUC of the tea extract were found to be significantly higher when compared to the mitragynine alone (830 ng/mL and 245181 ng×hr/mL). The renal clearance of the mitragynine (tea extract) I.V. and oral were 0.013 ± 0.002 and 0.025 ± 0.008 mL/min/kg and the renal clearance when mitragynine was administered I.V and orally were 0.021 ± 0.0052 and 0.07 ± 0.009 mL/min/kg. Also, the analysis of the commercial product reveled that multiple Kratom products had concentrations of 7-hydroxymitragynine that are substantially higher than those found in raw M. speciose leaves.

Conclusions: Mitragynine (tea extract) was found to have better oral bioavailability and kinetic profile compared to mitragynine. From the commercial Kratom products tested, some were found to contain artificially elevated concentrations of 7-hydroxymitragynine, the alkaloid responsible for M. speciosa's concerning mechanistic and side effect profile. This describes a unique form of product adulteration.

Supported by: Center of Research Excellence in Natural Products Neuroscience (CORE-NPN), Grant Number P20GM104932, which is funded by the National Institute of General Medical Sciences (NIGMS) at the National Institutes of Health (NIH) as one of its Centers of Biomedical Research Excellence (COBRE).

Structural characterization of the Rous Sarcoma Virus capsid protein in its tubular assembly and simulations of the self-assemblies of the HIV capsid protein

Jaekyun Jeon, Ivan Hung, Alok K. Mitra, Ambroise Desfosses, Xin Qiao, Daniel Huang, Peter L. Gor’kov, Rebecca C. Craven, Richard L. Kingston, Zhehong Gan, Fangqiang Zhu, and Bo Chen

Department of Physics, University of Central Florida

11:10 AM
Biophysical

The capsid proteins (CAs) of ortho-retroviruses share a common tertiary fold but form distinct capsids. They are promising antiviral drug targets and templates for versatile nano-assemblies. However, they are tough to characterize due to the strong polymorphism. In this work, solid state NMR was applied to characterize the CA tubular assembly of Rous sarcoma (RSV), a prototype of retrovirus. A novel resonance assignment strategy was developed that exploits the well-resolved NCACX spectra to facilitate the assignment of congested NCOCX spectra, which led to a nearly complete assignment (234 residue out of the 237-residue protein). Based on this, site-specific dynamics and secondary structural information were determined. Combining with constraints from cryo-EM, we established an atomic resolution model of the tubular assembly by molecular dynamics flexible fitting. Our model shows that significant structural rearrangements take place at flexible loops and the 310 helix regions, while the rest of the protein retains its structure upon assembly. The analyses of our model suggests the assembly polymorphism is attributed to the disorder of the trimer interface between C-terminal domains. In addition, the different contact angles between helices at assembly interfaces of tubular and planar assemblies for HIV and RSV CA. Based on simulations of our novel coarse grain model, it suggests the two systems undergo different assembly pathways.

Development of the reductive enyne Cope rearrangement

Sarah K. Scott, Katherine E. White and Alexander J. Grenning

Department of Chemistry, University of Florida, Gainesville FL 32611-7200, USA

09:10 AM
Organic Chemistry

Although the enyne Cope rearrangement has been known for several decades, it has not seen applications in synthetic chemistry due to low yields and product instability. However, through the implementation of a reductive variant, this reaction is now being exploited to access functionalized allenyl malonates, which can be further manipulated to generate a range of carbocyclic frameworks commonly found in natural products. This work not only demonstrates the first potential application of the enyne Cope rearrangement in the synthesis of natural products and their analogs, but also provides significant insight into overcoming the challenges previously associated with the transformation.

Synthesis and Characterization of Nature-derived Polymers with Potential to Replace Commodity Plastics

Olivier Nsengiyumva, Stephen A. Miller

George & Josephine Butler Polymer Research Laboratory, Center for Macromolecular Science & Engineering, Department of Chemistry, University of Florida, Gainesville, FL 32611, USA.

09:25 AM
PMSE/POLY

Over the last century, the commercial plastic industry burgeoned with a variety of finite resources allocated to polymer production. However, with their increased production and usage came a plethora of negative consequences to the environment, notably the inability of these polymers to degrade when disposed and only a small percentage being recycled. In addition, fossil fuel resources are dwindling, the key resource of most commercial polymers. This presentation will focus on new methods to access monomers from nature, and thus using them to synthesize renewable polymers. “Silicon acetal metathesis polymerization (SAMP)” is a methodology where silicon-based monomers and diols derived from plants are used to synthesize polysilicon acetals with glass transitions temperatures higher than that of polydimethylsiloxane (PDMS) and with relatively high melting points. SAMP also avoids the formation of deleterious byproducts such as corrosive acid (HCl). Other nature-derived monomers have also been used with the aim of replacing other non-renewable commodity plastics.

AlFe2B2 as Water Oxidation Catalyst

Dallas K. Mann,a Yury V. Kolen’ko,b and Michael Shatruka

a Department of Chemistry and Biochemistry, Florida State University, 95 Chieftan Way, Tallahassee, FL 32306, United States
b International Iberian Nanotechnology Laboratory, Avenida Mestre José Veiga s/n, 4715-330 Braga, Portugal

09:25 AM
Inorganic Chemistry

Currently, many highly important catalytic processes depend critically on compounds that contain noble metals such as platinum or rhenium. Such catalysts, however, are non-sustainable in the long run, due to the low abundance and high cost of such metals. To counter this issue, we have developed a guided approach to the discovery of new sustainable catalysts.  This approach utilizes machine-learning analsyis (deep neural networks, or DNN) to identify potentially promising catalysts, in particular, among complex metallic alloys (CMAs). The DNN analyzes atomic fingerprints, i.e. radial distribution functions, around crystallographically unique sites to effectively screen through a vast database of intermetallic structures and identify materials with transition metal sites similar in their coordination topology to the active sites in known state-of-the-art catalyst. The approach also builds on the active site isolation concept, which has proven to be useful for the design of efficient heterogeneous catalysts. Guided by the DNN analysis, we began synthesizing several promising CMAs, which are characterized by extremely large unit cell volumes. CMAs are known to contain unique structural defects which might contribute to unconventional catalytic behavior. Our initial investigation has begun with AlFe2B2, a ternary boride known for its remarkably high magnetocaloric effect near room temperature with a composition consisting of light earth-abundant elements.1 In this contribution, we will demonstrate that AlFe2B2 acts as excellent catalyst for the oxygen evolution reaction (OER). In addition to the good catalytic activity, this material has remained remarkably stable under catalytic conditions, providing nearly constant OER rate for over 300 hours. The nature of our neural network approach and the catalytic performance of AlFe2B2 will be discussed in this presentation.

References

Tan, X.; Chai, P.; Thompson, C. M.; Shatruk, M. J. Am. Chem. Soc.2013, 117, 17399-17411.

Atomistic insight towards fragmentary interactions of PEG in bioconjugates – an atomistic molecular dynamics study

Aravinda Munasinghe1, Akash Mathavan1,2, Akshay Mathavan1,2, Ping Lin1 and Coray M. Colina1,2

1 Department of Chemistry, University of Florida, Gainesville, FL 32611
2 Department of Materials Science and Engineering, University of Florida, Gainesville, FL 32611

04:50 PM
Computational Chemistry

Currently many polymers and their different architectures are being investigated to synthesize bioconjugates. Due to its biocompatibility, polyethylene glycol (PEG) has emerged as an interesting polymer for bio-conjugate synthesis. Though PEG has been extensively studied, how its interact with biomolecules is yet to be fully clarified. The purpose of this work was to explore how PEG interacts with the Bovine Serum Albumin (BSA) protein using atomistic molecular dynamics simulations. To understand conditions which promote PEG – BSA interactions, conjugated systems with different molecular weights (i.e., 2, 5, 10, and 20 kDa) and unbound PEG were studied. PEGylated polymers were conjugated to N-terminal as well as Lys116 to explore the effect of the conjugate site. In each system, contacts between the polymer and the protein were monitored to explore PEG – BSA interactions and the affinity of PEG towards the BSA was evaluated based on the total number of formed contacts. It was found that the affinity of PEG towards the protein surface increases as a function of molecular weight. Further analysis of these interactions has revealed that PEG could adopt extended or coil-like conformations near the protein surface where mainly hydrophobic or hydrophilic residues are predominant.

Structure predictions of mixed-metal solid state compounds

Michael Lufaso

University of North Florida

04:55 PM
Materials Chemisry

Advances in solid-state chemistry benefit from synthesis of new materials and the characterization of their structures and properties. Both exploratory and targeted synthetic methods have unique advantages in the synthesis of new materials. These methods have been used to prepare mixed-metal solid state compounds, which exhibit structural variety and diverse physical properties. Structure prediction software based on the bond valence approach has been developed to predict the structure of a range of phase compositions. Developments include structure stability predictions and temperature dependent calculations, enabling the examination of structural phase transitions and the associated changes in unit cells, atomic positions, bond distances, bond angles, etc. Representative mixed metal solid state systems are examined in the context of the predicted and experimental structures.

Increased post-translation modification of eIF5A contributes to TDP43 proteinopathy

Shayna Smeltzer, Zain Quadri, Frank Zamudio, Jordan Hunter, Daniel C Lee, Maj-Linda B Selenica

College of Pharmacy, University of South Florida

10:15 AM
Biochemistry / Chem Bio.

The hallmark of TDP-43 proteinopathy is loss of nuclear function and accumulation as cytoplasmic inclusions. Recent evidence suggests for unique accumulation of TDP-43 in stress granules (SG) as disease progresses. In patients, TDP-43 pathology results in impairment of motor neuron function (ALS) and cognitive dysfunction (FTD). Hypusination of eIF5A (eIF5AhypK50) denotes its activation and cytoplasmic localization where it also binds to various RNA binding proteins. Its overall cellular function is translational elongation but translation inhibition in stress granules also occurs, as shown in stress-induced cellular models. While this is a common feature of SG biology, the activity of eIF5AhypK50 in SG can be problematic for TDP-43 proteinopathies. It can lead to further seeding of TDP-43 and translation of aberrant truncated TDP-43 forms adding to cytoplasmic aggregation once SGs dissolve. We show increased levels of enzymes responsible for hypusination in brain tissue from AD patient as well as in TDP-43 animal models. The animal model also displayed significant increase in hypusination levels, suggesting that its augmentation underlies the progression of the disease. Further, we know that protein–protein binding occurs between eIF5AhypK50 and TDP-43, and just by inhibiting hypusination, phosphorylated and total TDP-43 levels are reduced in the cytoplasm. It is however unknown the mechanism by which this occur. We predict that inhibition of hypusination will reduce TDP-43 burden and provide a strategy for therapies in TDP-43 proteinopathy. We hypothesize that eIF5AhypK50 regulates TDP-43 trafficking via several potential mechanisms, including protein-protein interactions, promoting cytoplasmic accumulation, translational regulation and the government of SG biology. We predict that it is through these mechanisms that eIF5AhypK50 orchestrates TDP-43 trafficking to cytoplasm and determines the biological signature of SGs. Our team has developed several unique tools to evaluate the efficacy of such approaches and dissect the mechanism of action through which eIF5AhypK50 affects TDP-43 pathology. We already know that pharmacological inhibition effectively reduces TDP-43 accumulation in SG in cells. However, we do not know if modulations of eIF5AhypK50 have neuronal efficacy or if it yields beneficial outcomes in the brain. Therefore, we have employed several innovative techniques, siRNA screening, antisense oligonucleotides and viral constructs to examine the neuronal role of eIF5AhypK50 in primary neurons and in TDP43 transgenic model.

Free Energy Sampling of Long-Timescale Biomolecular Dynamics: The Orthogonal Space Sampling Paradigm

Lianqing Zheng, Dongsheng Wu, Karen Corbett, Erick Aitchison, Steven Austin, Xubin Li, Chao Lv, William Harris, and Wei Yang

Department of Chemistry and Biochemistry & Institute of Molecular Biophysics
Florida State University

05:45 PM
Computational Chemistry

In the past decades, various enhanced sampling schemes and methods have been proposed towards the dream of practical sampling of free energy surfaces underlying biologically relevant biological processes. Despite victories declared by various mathematical methods, their ineffectiveness has been increasingly clear; physical basis of their limitation, particularly from the viewpoint of energy flow acceleration, is also more obvious to the community. At the same time, a physics-centered scheme, the orthogonal space sampling (OSS) theory, has been emerging. The recent development and large-scale tests shows that robust free energy sampling of long-timescale biomolecular processes has been achieved. This talk will serve as a part of official announcement of this breakthrough.

Additive Manufacturing for the Future Warfighter

Jaret C. Riddick

Army Research Labs

04:00 PM
Additive Manufacturing

Army Research Lab is conducting research to enable the use of additive manufacturing to reduce the logistical burden of the future Warfighter.  ARL researchers are investigating additive manufacturing to establish research prototypes such as mission-matched UAS concepts built on-demand at the point-of-need and multifunctional components for maintenance-free air vehicle platforms.

Encapsulation of High Surface Particulates into Sol-gel Matrix and Their Use in Environmental Pollution Mitigation

Abuzar Kabir, Cassie-Jo McBride, Kenneth G. Furton.

Florida International University

05:45 PM
Environmental

Due to the explosive growth of human activities in recent years, thousands of toxic and hazardous synthetic organic compounds produced for industrial, domestic and agricultural purpose have continued to pollute fresh water systems. Many of these pollutants are classified as persistent organic pollutants (POPs). When POPs are released into the environment, they remain unchanged for a long period. Due to their prolonged presence in the environment, many of these pollutants finally find their way in the food chain, with severe implications in the health and well-being of human.  As such, it is imperative that these compounds be efficiently removed from environmental water through more efficient sewerage treatment processes and other reliable, yet inexpensive remediation techniques.

Among many classical processes used in removing pollutants from water, adsorption is one of the most effective removal techniques. A large number of carbonaceous adsorbents including activated carbon, carbon nanotube, biochar, graphene, calixarenes, poly(styrene-divinyl benzene), carboxen, fullerene, cation exchange resins, anion exchange resins and many others are used as adsorbents in sewerage treatment plants. These adsorbents offer a large variety of intermolecular interactions towards the analytes including µ-µ stacking interactions, cation-µ bonding interactions, electron donor-acceptor interactions, hydrophobic interactions, hydrogen bonding interaction, cation exchange, anion exchange, dipole-dipole interactions etc. Many of these adsorbents possess extremely high surface area and demonstrate strong tendency to form agglomeration. As such, when they are used in their pristine form, a large portion of their available surface area cannot be readily accessed by the analytes due to their agglomeration. As a result, the adsorption capacities of these adsorbents remain largely unexploited during their applications. The agglomeration of these unique particulate matters can be inhibited by encapsulated them into sol-gel silica network. Sol-gel chemistry provides a convenient and mild reaction pathway to create pure silica or organically modified silica 3-D network. Addition of adsorbent particles into the sol solution during sol-gel synthesis results in a sol-gel composite sorbent system with homogeneously trapped particulate matters. Due to the inherently porous and open architecture of sol-gel silica network, the encapsulated particulate matters maintain their high surface area as well as freely accessible interaction sites. As such, the synergistic combination of silica chemistry as well as the chemistry of particulate matters result in robust composite material systems capable of exerting intermolecular/ionic interactions towards a wide variety of analytes including polar, medium polar, nonpolar, ionic, and metal species and successfully trap them in the sol-gel composite sorbent matrices.

Analytical data obtained from a number of real-life applications of the sol-gel composite sorbents including endocrine disrupting chemicals (EDCs), Pharmaceuticals and personal care products (PPCPs), polycyclic aromatic hydrocarbon (PAHs) in environmental water will be presented showcasing their advantages, extraction characteristics, performance superiority, and analytical figures of merit.

Synthesis and Characterization of Lead Halide Perovskites for Solid State Lighting

Edward T. Nguyen

Florida State University

05:45 PM
Materials Chemisry

Down-shifting phosphors are routinely used in solid state lighting to convert higher energy UV or blue light to visible light. However, color quality of commercial LEDs are modest and new RGB phosphors are needed to tune the color of light. Commercial LEDs are composed of bulk semiconductors that typically contain materials on the DOE high risk index. For improving performance of down-shifting phosphors, size of the phosphor must be reduced to sub 10nm to reduce scattering of the pump led, the host lattice must minimize the amount of rare earth metals used, and must absorb pump LED irradiation and convert to pure red, green, and blue emission for optimal color quality. Here we present the synthesis of lanthanide-doped lead-halide perovskites (CsPbX3; X = Cl, Br, I). Lanthanide emission is accomplished by energy transfer from surface ligands to lanthanide metal centers by using the molecular antenna effect. Optical measurements of the nano-perovskites will be discussed including absorption, emission, lifetime, and quantum yields. Ligand exchanges were completed in efforts to improve quantum efficiencies and the nanoperovskites were characterized by pXRD, TEM, EPR, and FT-IR.

Detection of Adulterants in Drug Screening Analysis

Bianca Olivieri 

Mark Maric Ph.D.

Candice Bridge Ph.D.

Bianca Olivieri- University of Central Florida Chemistry Department
Mark Maric Ph.D. - National Center for Forensic Science
Candice Bridge Ph.D. - University of Central Florida Chemistry Department /National Center for Forensic Science

10:15 AM
Analytical Chemistry

Drug abuse has been problematic for centuries; however, the technology to detect drugs and their metabolites in bodily fluids has only been available for less than 50 years.1 To detect the use of illicit drugs in urinalysis, testing typically begins with a screening technique in the form of an immunoassay, such as Enzyme-Linked Immunosorbent Assay (ELISA). Although the response accuracy of immunoassays has increased, it remains only 95% accurate for urine screenings, which may be effectively lowered with the addition of adulterants into the urine matrix.2 To counteract a potential false-negative result, analysts will often use adulterant test strips to detect the presence of additional products. An understanding of this screening technique and the influence of adulterants on accurate results is crucial for workplace drug testing, criminal proceedings and the compliance of court probations.

In this study approximately thirty urine samples were obtained via volunteers under UCF IRB No: SBE-16-12568. Included with the samples were completed surveys detailing drug use, the frequency of stated drug use, and other contributing factors. Based on the provided information, samples were identified containing known types of illicit drugs and their metabolites (i.e. THC, cocaine, amphetamines, and benzodiazepines). No known samples contained traces of α-PVP, therefore a clean urine sample was taken and spiked with an α-PVP standard. Urine samples were then adulterated at set concentrations of 5, 10, 25, and 50 % v/v or w/v. Adulterants in this study included: bleach, vinegar, eye drops, Drano®, nitrite, table salt, and hand sanitizer. The adulterated and unadulterated samples were then analyzed via ELISA protocol. Results with ELISA revealed that certain adulterants (e.g. bleach, eye drops, Drano®) consistently decreased the detected concentration of drug metabolites to below cut-off thresholds. In conjunction, adulterant test strips AdultaCheck® 6 (AC6) and Intect™ 7 (I7), were utilized to determine if and at what concentration the adulterants could be detected. Data has revealed that the majority of the adulterants were unable to be detected at a low 5 % v/v adulteration level. This is a cause of concern, due to the ability of these adulterants to drastically decrease the drug/metabolite concentration using ELISA. The combination of these results suggest that a new urinalysis technique needs to be identified in order to effectively detect the presence of drug metabolites in the case of adulterant addition.

Keywords: ELISA, Adulterant Test Strips, Urinalysis

1.Bennett, J. B., Introduction. In Preventing Workplace Substance Abuse: Beyond Drug Testing to Wellness, Bennett, J. B.; Lehman, W. E. K., Eds. American Psychological Association: Washington, DC, 2003

2.Schütz, H.; Paine, A.; Erdmann, F.; Weiler, G.; Verhoff, M. A., Immunoassays for drug screening in urine. Forensic Science, Medicine, and Pathology 2006, 2 (2), 75-83.

 

 

Terbium(III) doped nano-spinels as green emitters for solid state lighting.

David A. Hardy, Geoffrey F. Strouse

Florida State University

10:15 AM
Inorganic Chemistry

Down-shifting phosphors are routinely used in solid state lighting to convert higher energy UV or blue light to visible light. However, color quality of commercial LEDs are modest and new RGB phosphors are needed to tune the color of light. Commercial LEDs are composed of bulk semiconductors that typically contain materials on the DOE high risk index. For improving performance of down-shifting phosphors, size of the phosphor must be reduced to sub 10nm to reduce scattering of the pump led, the host lattice must be composed of earth abundant materials, and must absorb pump LED irradiation and convert to pure red, green, and blue emission for optimal color quality. Here we present the microwave synthesis of nanophosphors doped with Terbium(III) to accomplish green emission. Lanthanide emission is accomplished by energy transfer from surface ligands to lanthanide metal centers by using the molecular antenna effect. Optical measurements of the nano-spinel will be discussed including absorption, emission, lifetime, and quantum yields. Ligand exchanges were completed in efforts to improve quantum efficiencies and the nanospinels were characterized by pXRD, TEM, EPR, and FT-IR.

NSF 101: The Process of Preparing, Submitting, and Reviewing Proposals for The National Science Foundation

Tarek Sammakia

National Science Foundation and the University of Colorado

09:30 AM
Organic Chemistry

The process of preparing, submitting, and reviewing proposals for Chemistry Division of The National Science Foundation (NSF) will be described. This talk is geared at those in early stages of their careers and will provide some basic advice about the process of obtaining funding from the NSF.

Kinetic Measurements of CO+ and CO2+ Reactions with N and O Atoms for Models of the Martian Atmosphere

Jake Tenewitz1, Tri Le1, Shaun G. Ard2, Nicholas S. Shuman2, Albert A. Viggiano2, and Joshua J. Melko1

1. University of North Florida, Department of Chemistry, Jacksonville, FL
2. Air Force Research Laboratory, Kirtland Air Force Base, Albuquerque, NM

10:15 AM
Physical Chemistry

We have measured rate constants for CO+ and CO2+ reacting with N and O atoms using a flow tube apparatus equipped with a microwave discharge atom source. We report new room-temperature rate constants for these reactions that are much less efficient than previously thought, and the reaction of CO2+ + O is observed to yield O2+ exclusively, in contrast to an existing measurement in the literature. Experimental work was supplemented by molecular structure calculations. Calculated pathways show the sensitivity of kinetic barriers  to theoretical method, and indicate high level ab initio methods are required for accurate energetics. Our findings suggest that models of planetary atmospheres and the interstellar medium need to be updated accordingly. We will highlight a recently published model of the Martian atmosphere utilizing our new values.

A gold nanoparticle/aptamer-based multi-channel paper microfluidic device designed for the scheduled drugs.

Ling Wang, Bruce McCord

Florida International University

10:35 AM
Analytical Chemistry

Designed aptamer has been developed to successfully identify some drugs of abuse in the last years.  Gold nanoparticles are usually used as a colorimetric detection or an electrical detection of drugs in the solutions.  These tests are based on the operations of chemical reactions, so they require the special knowledge of the chemical reactions.  We have been working on an alternative platform for the gold nanoparticles/ aptamers detection based on paper microfluidic devices.  Paper microfluidic devices are prepared with a wax-ink printer, thermal laminator, chromatography paper, gold nanoparticles and aptamers.  We have created a chip with a multiple-channel design which utilized the gold nanoparticles and special aptamers as a ready-to-use format.  In the field, samples are dissolved in a carrier solvent in vials and then applied to the paper just before the analysis.  The drug sample in the moving solution moved through the channel via capillary actions, reacted with the designed aptamers, and changed the color of gold nanoparticles with salted-induced aggregations.  Aptamers in each channel react with the target drug and the gold nanoparticles area turn from red to black indicating the presence of the target drug.  The entire process takes 5-10 minutes.  The devices can be used in different conditions where the suspected powders need the identification.   These devices are easy to prepare and inexpensive to operate without the special knowledge or training.

Machine learning approaches to evaluate correlation patterns in allosteric signaling: a case study of the PDZ2 domain

Mohsen Botlani, Ahnaf Siddiqui, Sameer Varma

University of South Florida

06:10 PM
Computational Chemistry

Many proteins are regulated by dynamic allostery wherein regulator-induced changes in structure are comparable with thermal fluctuations. Consequently, understanding their mechanisms requires assessment of relationships between and within conformational ensembles of different states. Here we show how machine learning based approaches can be used to simplify this high-dimensional data mining task and also obtain mechanistic insight. In particular, we use these approaches to investigate two fundamental questions in dynamic allostery. Firstly, how do regulators modify inter-site correlations in conformational fluctuations ($C_{ij}$)? Secondly, how are regulator-induced shifts in conformational ensembles at two different sites in a protein related to each other? We address these questions in the context of the human PTP1E's PDZ2 domain, which is a model protein for studying dynamic allostery. We use molecular dynamics to generate conformational ensembles of the PDZ2 domain in both the regulator-bound and regulator-free states. The employed protocol reproduces methyl deuterium order parameters from NMR. Results from unsupervised clustering of $C_{ij}$ combined with flow analyses of weighted graphs of $C_{ij}$ show that regulator binding significantly alters the global signaling network in the protein; however, not by altering the spatial arrangement of strongly interacting amino acid clusters, but by modifying the connectivity between clusters. Additionally, we find that regulator-induced shifts in conformational ensembles, which we evaluate by repartitioning ensembles using supervised learning, are, in fact, correlated. This correlation $\Delta_{ij}$ is less extensive compared to $C_{ij}$, but in contrast to $C_{ij}$, $\Delta_{ij}$ depends inversely on the distance from the regulator binding site. Assuming that $\Delta_{ij}$ is an indicator of the transduction of the regulatory signal leads to the conclusion that the regulatory signal weakens with distance from the regulatory site. Overall, this work provides new approaches to analyze high-dimensional molecular simulation data, and also presents applications that yield new insight into dynamic allostery.

Experimentally Correlating the Spatial Distribution of Fluorine to the Growth of Anatase TiO2 Crystal Facets

Justin R. Mulcahy, Shuai He, Decarle S. Jin, Wenxiao Guo, Sarah Arteta, Esdras Lopez, Zihua Zhu, and Wei David Wei

Department of Chemistry and Center for Catalysis, University of Florida, Gainesville, Florida 32611, United States
Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99354, United States

06:05 PM
Materials Chemisry

Although the capability of fluorine to selectively stabilize anatase titanium dioxide (TiO2) crystal facets has been recognized, resolving its physical distribution remains empirically elusive. Here, we provide direct experimental evidence to reveal the spatial location of fluorine on the surface of anatase TiO2 truncated bipyramid (TB) single crystals using nanoscale secondary ion mass spectrometry (NanoSIMS). Fluorine was found to preferentially adsorb on the (001) facet over the (101) facet of TBs. Moreover, NanoSIMS depth profiling exhibited a significantly different fluorine distribution between these two facets in the near-surface region, which correlates the essential role of lattice fluorine doping with the anisotropic crystal growth of TBs.

Giant Molecules: Exploring Synthetic Parameters on the Path to New Mn-O Torus-like Clusters

Ashlyn Hale, Khalil A. Abboud, George Christou*

Department of Chemistry, University of Florida, PO Box 117200 Gainesville, FL 32611-7200, USA

10:35 AM
Inorganic Chemistry

The discovery of fascinating giant molecular clusters of paramagnetic metal ions (metal nuclearity of 30 or greater, and diameters up to 4.3 nm) has garnered immense interest due to their relevance to chemistry, physics, and materials science. The allure of diverse giant clusters is rooted in their fantastic features, such as their aesthetically-pleasing architectures, nanoscale size regime, and phenomenal physical properties. These features uniquely position giant clusters at the interface between the classical and quantum realms. Mn-O clusters are at the forefront of 3d transition metal giant clusters, owing to the relevance of Mn to molecular magnetism, especially single-molecule magnets (SMMs). The largest homometallic Mn-O cluster and SMM to date was synthesized by our group over a decade ago: the Mn84­ torus is a SMM and with a diameter of ~4.3 nm, it truly straddles the classical-quantum interface. Over a decade later, our group reported a second member in the family, the Mn­70 torus, the second largest SMM and Mn-O cluster to date. Herein, we present the revitalized and systematic investigation into this family of giant torus-like clusters, in order to further deduce which synthetic and structural parameters dictate the curvature and thus the nuclearity of the product, paving the way for targeted syntheses and the discovery of new giant Mn-O clusters.

Green Methods for the Synthesis of Anti-Cancer Resveratrol Analogues

Daniel H. Paull

Florida Gulf Coast University

10:15 AM
Organic Chemistry

Resveratrol analogues have been widely tested in all kinds of aging-related disorders in the last decade, and their use has only increased because of successes in several diverse areas, including anti-inflammatory, cardioprotective, and anti-cancer. Likewise, we need an ever-expanding library of synthetic methods for their production, especially ones that are easy, quick, efficient, and clean. These green principles guide our method development, and we have three distinct methods to present.

The products we synthesize are tested against various breast cancer cell lines, and we have found several that are active against, and induce metastasis-inhibiting morphological changes in, triple-negative breast cancer cell lines. We are currently designing and synthesizing a second, more focused set of compounds for testing. This application will be presented along with the advantages of each green method for these syntheses.