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Articles 1 - 20 of 20
Full-Text Articles in Physical Sciences and Mathematics
Synthesis Of 5,6-Diaminoacenaphthylene By Reduction Of Sterically Crowded Nitro Groups With Sodium Dithionite, Amber J. Dood, Patrick A. Fisher, Christine L. Bodden, Luke J. Peterson, Kathryn A. Lindberg, Trevor A. Coeling, Douglas C. Yarbrough, Jason G. Gillmore
Synthesis Of 5,6-Diaminoacenaphthylene By Reduction Of Sterically Crowded Nitro Groups With Sodium Dithionite, Amber J. Dood, Patrick A. Fisher, Christine L. Bodden, Luke J. Peterson, Kathryn A. Lindberg, Trevor A. Coeling, Douglas C. Yarbrough, Jason G. Gillmore
Faculty Publications
5,6-Diaminoacenaphthylene was synthesized in four steps from acenaphthene. This seemingly simple molecule provides unique synthetic challenges because it is relatively difficult to reduce the nitro groups and the molecule contains a particularly reactive double bond. It was determined that the only feasible sequence for the synthesis was to nitrate acenaphthene, then brominate, eliminate, and finally selectively reduce. Several reduction methods were attempted before finding one that would completely reduce both nitro groups while leaving the double bond intact.
Information-Driven Inverse Approach To Disordered Solids: Applications To Amorphous Silicon, Dil K. Limbu, Raymond Atta-Fynn, David A. Drabold, Stephen R. Elliott, Parthapratim Biswas
Information-Driven Inverse Approach To Disordered Solids: Applications To Amorphous Silicon, Dil K. Limbu, Raymond Atta-Fynn, David A. Drabold, Stephen R. Elliott, Parthapratim Biswas
Faculty Publications
© Physical Review Materials
Pva/Chitosan/Silver Nanoparticles Electrospun Nanocomposites: Molecular Relaxations Investigated By Modern Broadband Dielectric Spectroscopy, Mohammad K. Hassan, Ahmed Abukmail, Alaa J. Hassiba, Kenneth A. Mauritz, Ahmed A. Elzatahry
Pva/Chitosan/Silver Nanoparticles Electrospun Nanocomposites: Molecular Relaxations Investigated By Modern Broadband Dielectric Spectroscopy, Mohammad K. Hassan, Ahmed Abukmail, Alaa J. Hassiba, Kenneth A. Mauritz, Ahmed A. Elzatahry
Faculty Publications
In this study, we used broadband dielectric spectroscopy to analyze polymer nanofibers of poly(vinyl alcohol)/chitosan/silver nanoparticles. We also studied the effect of incorporating silver nanoparticles in the polymeric mat, on the chain motion dynamics and their interactions with chitosan nanofibers, and we calculated the activation energies of the sub-Tg relaxation processes. Results revealed the existence of two sub-Tg relaxations, the first gets activated at very low temperature (−90 °C) and accounts for motions of the side groups within the repeating unit such as –NH2, –OH, and –CH2OH in chitosan and poly(vinyl alcohol). The second …
Metallo-Polyelectrolytes As A Class Of Ionic Macromolecules For Functional Materials, Tianyu Zhu, Ye Sha, Jing Yan, Parasmani Pageni, Md Anisur Rahman, Yi Yan, Chuanbing Tang
Metallo-Polyelectrolytes As A Class Of Ionic Macromolecules For Functional Materials, Tianyu Zhu, Ye Sha, Jing Yan, Parasmani Pageni, Md Anisur Rahman, Yi Yan, Chuanbing Tang
Faculty Publications
The fields of soft polymers and macromolecular sciences have enjoyed a unique combination of metals and organic frameworks in the name of metallopolymers or organometallic polymers. When metallopolymers carry charged groups, they form a class of metal-containing polyelectrolytes or metallo-polyelectrolytes. This review identifies the unique properties and functions of metallo-polyelectrolytes compared with conventional organo-polyelectrolytes, in the hope of shedding light on the formation of functional materials with intriguing applications and potential benefits. It concludes with a critical perspective on the challenges and hurdles for metallo-polyelectrolytes, especially experimental quantitative analysis and theoretical modeling of ionic binding.
Unexpected Effects Of Inorganic Phosphate Glass On Crystallization And Thermo-Rheological Behavior Of Polyethylene Terephthalate, Kyoungtae Kim, Shahab Kashani Rahimi, Todd M. Alam, Eric G. Sorte, Joshua U. Otaigbe
Unexpected Effects Of Inorganic Phosphate Glass On Crystallization And Thermo-Rheological Behavior Of Polyethylene Terephthalate, Kyoungtae Kim, Shahab Kashani Rahimi, Todd M. Alam, Eric G. Sorte, Joshua U. Otaigbe
Faculty Publications
The effects of ultra-low glass transition temperature (Tg) phosphate glass (Pglass) on the thermal, morphological, rheological, mechanical, and crystallization properties of hybrid Pglass/poly(eththylene terephthalate)(PET) were investigated. Nano- and micro-scale distribution of the Pglass in the PET polymer matrix was observed. The polydispersed Pglass in the PET matrix functioned as a nucleation agent, resulting in increasing crystallization temperature. The Pglass in the PET matrix decreased the Tg, indicating a plasticizing effect of the Pglass in the hybrids that was confirmed by the significantly decreased complex viscosity of the PET matrix. In addition, with increasing temperature, a non-terminal …
Data On Ion Composition And X-Ray Diffraction Patterns Of Biosolids From Wastewater Treatment Plants In Lufkin And Nacogdoches, Texas, Usa, Kefa Karimu Onchoke, Christopher M. Franclemont, Paul W. Weatherford
Data On Ion Composition And X-Ray Diffraction Patterns Of Biosolids From Wastewater Treatment Plants In Lufkin And Nacogdoches, Texas, Usa, Kefa Karimu Onchoke, Christopher M. Franclemont, Paul W. Weatherford
Faculty Publications
The data presented in this article is related to the research article entitled, “Structural Characterization and Evaluation of Municipal Wastewater Sludge (Biosolids) from two Rural Wastewater Treatment Plants in East Texas, USA”, Onchoke, KK, Franclemont, C.M., Spectrochim. Acta A, In press[1]. The XRD profiles and composition of biosolids from wastewater treatment plant is presented. This study describes the composition of XRD crystalline phase patterns of the wastewater sludge. After the removal of the Ka2 peaks the d-spacing and hkl values were determined. In addition, the ion chromatographic profile of the seven anions (NO3-, NO2 …
Quinolines From The Cyclocondensation Of Isatoic Anhydride With Ethyl Acetoacetate: Preparation Of Ethyl 4-Hydroxy-2-Methylquinoline-3-Carboxylate And Derivatives, Nicholas Jentsch, Jared D. Hume, Emily B. Crull, Samer M. Beauti, Amy H. Pham, Julie A. Pigza, Jacques Kessl, Matthew G. Donahue
Quinolines From The Cyclocondensation Of Isatoic Anhydride With Ethyl Acetoacetate: Preparation Of Ethyl 4-Hydroxy-2-Methylquinoline-3-Carboxylate And Derivatives, Nicholas Jentsch, Jared D. Hume, Emily B. Crull, Samer M. Beauti, Amy H. Pham, Julie A. Pigza, Jacques Kessl, Matthew G. Donahue
Faculty Publications
A convenient two-step synthesis of ethyl 4-hydroxy-2-methylquinoline-3-carboxylate derivatives has been developed starting from commercially available 2-aminobenzoic acids. In step 1, the anthranilic acids are smoothly converted to isatoic anhydrides using solid triphosgene in THF. In step 2, the anhydride electrophiles are reacted with the sodium enolate of ethyl acetoacetate, generated from sodium hydroxide, in warm N,N-dimethylacetamide resulting in the formation of substituted quinolines. A degradation–build-up strategy of the ethyl ester at the 3-position allowed for the construction of the α-hydroxyacetic acid residue required for the synthesis of key arylquinolines involved in an HIV integrase project.
Enhancement Of Triplet-Sensitized Upconversion In Rigid Polymers Via Singlet Exciton Sink Approach, Steponas Raišys, Saulius Juršėnas, Yoan C. Simon, Christoph Weder, Karolis Kazlauskas
Enhancement Of Triplet-Sensitized Upconversion In Rigid Polymers Via Singlet Exciton Sink Approach, Steponas Raišys, Saulius Juršėnas, Yoan C. Simon, Christoph Weder, Karolis Kazlauskas
Faculty Publications
To increase the practical usefulness of solid-state sensitized upconversion (UC) materials as components of solar energy harvesting systems, it is important to identify and suppress loss mechanisms, and increase the UC quantum yield (ΦUC). Here we focus on a benchmark UC system consisting of the emitter 9,10-diphenylanthracene (DPA) and the sensitizer platinum octaethylporphyrin (PtOEP) in a rigid poly(methyl methacrylate) (PMMA) matrix, and show that one of the major losses originates from Förster resonant energy transfer (FRET) from DPA back to PtOEP. Even though DPA emission lies within the PtOEP transparency window, the quantitative assessment of singlet exciton diffusion …
Rational Design Of Superhydrophilic/Superoleophobic Surfaces For Oil-Water Separation Via Thiol-Acrylate Photopolymerization, Li Xiong, Wei Guo, Benjamin M. Alameda, Reese Sloan, William D. Walker, Derek L. Patton
Rational Design Of Superhydrophilic/Superoleophobic Surfaces For Oil-Water Separation Via Thiol-Acrylate Photopolymerization, Li Xiong, Wei Guo, Benjamin M. Alameda, Reese Sloan, William D. Walker, Derek L. Patton
Faculty Publications
We report a simple, rapid, and scalable strategy to fabricate surfaces exhibiting in-air superoleophobic/superhydrophilic wetting via sequential spray deposition and photopolymerization of nanoparticle-laden thiol–acrylate resins comprising both hydrophilic and oleophobic chemical constituents. The combination of spray deposition with nanoparticles provides hierarchical surface morphologies with both micro- and nanoscale roughness. Mapping the wetting behavior as a function of resin composition using high- and low-surface-tension liquid probes enabled facile identification of coatings that exhibit a range of wetting behavior, including superhydrophilic/superoleophilic, superhydrophobic/superoleophobic, and in-air superhydrophilic/superoleophobic wetting. In-air superhydrophilic/superoleophobic wetting was realized by a dynamic rearrangement of the interface to expose a greater …
Role Of Stone-Wales Defects On The Interfacial Interactions Among Graphene, Carbon Nanotubes, And Nylon 6: A First-Principles Study, Sanjiv K. Jha, Michael Roth, Guido Todde, J. Paige Buchanan, Robert D. Moser, Manoj K. Shukla, Gopinath Subramanian
Role Of Stone-Wales Defects On The Interfacial Interactions Among Graphene, Carbon Nanotubes, And Nylon 6: A First-Principles Study, Sanjiv K. Jha, Michael Roth, Guido Todde, J. Paige Buchanan, Robert D. Moser, Manoj K. Shukla, Gopinath Subramanian
Faculty Publications
We investigate computationally the role of Stone-Wales (SW) defects on the interfacial interactions among graphene, carbon nanotubes (CNTs), and Nylon 6 using density functional theory (DFT) and the empirical force-field. Our first-principles DFT calculations were performed using the Quantum ESPRESSO electronic structure code with the highly accurate van der Waals functional (vdW-DF2). Both pristine and SW-defected carbon nanomaterials were investigated. The computed results show that the presence of SW defects on CNTs weakens the CNT-graphene interactions. Our result that CNT-graphene interaction is much stronger than CNT-CNT interaction indicates that graphene would be able to promote the dispersion of CNTs in …
Nickel Exposure Reduces Enterobactin Production In Escherichia Coli, Clorissa L. Washington-Hughes, Geoffrey T. Ford, Alsten D. Jones, Kimberly Mcrae, Franklin Wayne Outten
Nickel Exposure Reduces Enterobactin Production In Escherichia Coli, Clorissa L. Washington-Hughes, Geoffrey T. Ford, Alsten D. Jones, Kimberly Mcrae, Franklin Wayne Outten
Faculty Publications
Escherichia coli is a well- studied bacterium that can be found in many niches, such as industrial wastewater, where the concentration of nickel can rise to low- millimolar levels. Recent studies show that nickel exposure can repress pyochelin or induce pyo-verdine siderophore production in Pseudomonas aueroginosa. Understanding the mo-lecular cross- talk between siderophore production, metal homeostasis, and metal toxicity in microorganisms is critical for designing bioremediation strategies for metal- contaminated sites. Here, we show that high- nickel exposure prolongs lag phase duration as a result of low- intracellular iron levels in E. coli. Although E. coli cells respond to low- …
Nickel Exposure Reduces Enterobactin Production In Escherichia Coli, Clorissa L. Washington – Hughes, Geoffrey T. Ford, Alsten D. Jones, Kimberly Mcrae, Franklin W. Outten
Nickel Exposure Reduces Enterobactin Production In Escherichia Coli, Clorissa L. Washington – Hughes, Geoffrey T. Ford, Alsten D. Jones, Kimberly Mcrae, Franklin W. Outten
Faculty Publications
Escherichia coli is a well- studied bacterium that can be found in many niches, such as industrial wastewater, where the concentration of nickel can rise to low- millimolar levels. Recent studies show that nickel exposure can repress pyochelin or induce pyo-verdine siderophore production in Pseudomonas aueroginosa. Understanding the mo-lecular cross- talk between siderophore production, metal homeostasis, and metal toxicity in microorganisms is critical for designing bioremediation strategies for metal- contaminated sites. Here, we show that high- nickel exposure prolongs lag phase duration as a result of low- intracellular iron levels in E. coli. Although E. coli cells respond to low- …
Hiv-1 Integrase-Targeted Short Peptides Derived From A Viral Protein R Sequence, Xue Zhi Zhao, Mathieu Métifiot, Evgeny Kiselev, Jacques Kessl, Kasthuraiah Maddali, Christophe Marchand, Mamuka Kvaratskhelia, Yves Pommier, Terrence R. Burke Jr.
Hiv-1 Integrase-Targeted Short Peptides Derived From A Viral Protein R Sequence, Xue Zhi Zhao, Mathieu Métifiot, Evgeny Kiselev, Jacques Kessl, Kasthuraiah Maddali, Christophe Marchand, Mamuka Kvaratskhelia, Yves Pommier, Terrence R. Burke Jr.
Faculty Publications
HIV-1 integrase (IN) inhibitors represent a new class of highly effective anti-AIDS therapeutics. Current FDA-approved IN strand transfer inhibitors (INSTIs) share a common mechanism of action that involves chelation of catalytic divalent metal ions. However, the emergence of IN mutants having reduced sensitivity to these inhibitors underlies efforts to derive agents that antagonize IN function by alternate mechanisms. Integrase along with the 96-residue multifunctional accessory protein, viral protein R (Vpr), are both components of the HIV-1 pre-integration complex (PIC). Coordinated interactions within the PIC are important for viral replication. Herein, we report a 7-mer peptide based on the shortened Vpr …
Unraveling Substituent Effects On The Glass Transition Temperatures Of Biorenewable Polyesters, Xiaopeng Yu, Junteng Jia, Shu Xu, Ka Un Lao, Maria J. Sanford, Ramesh K. Ramakrishnan, Sergei I. Nazarenko, Thomas R. Hoye, Geoffrey W. Coates, Robert A. Distasio Jr.
Unraveling Substituent Effects On The Glass Transition Temperatures Of Biorenewable Polyesters, Xiaopeng Yu, Junteng Jia, Shu Xu, Ka Un Lao, Maria J. Sanford, Ramesh K. Ramakrishnan, Sergei I. Nazarenko, Thomas R. Hoye, Geoffrey W. Coates, Robert A. Distasio Jr.
Faculty Publications
Converting biomass-based feedstocks into polymers not only reduces our reliance on fossil fuels, but also furnishes multiple opportunities to design biorenewable polymers with targeted properties and functionalities. Here we report a series of high glass transition temperature (Tg up to 184 °C) polyesters derived from sugar-based furan derivatives as well as a joint experimental and theoretical study of substituent effects on their thermal properties. Surprisingly, we find that polymers with moderate steric hindrance exhibit the highest Tg values. Through a detailed Ramachandran-type analysis of the rotational flexibility of the polymer backbone, we find that additional steric hindrance does …
Facially Amphiphilic Polyionene Biocidal Polymers Derived From Lithocholic Acid, Mitra S. Ganewatta, Md Anisur Rahman, Louis Mercado, Tinom Shokfai, Alan W. Decho, Theresa M. Reineke, Chuanbing Tang
Facially Amphiphilic Polyionene Biocidal Polymers Derived From Lithocholic Acid, Mitra S. Ganewatta, Md Anisur Rahman, Louis Mercado, Tinom Shokfai, Alan W. Decho, Theresa M. Reineke, Chuanbing Tang
Faculty Publications
Bacterial infections have become a global issue that requires urgent attention, particularly regarding to emergence of multidrug resistant bacteria. We developed quaternary amine-containing antimicrobial poly(bile acid)s that contain a hydrophobic core of lithocholic acid in the main-chain. Interestingly, by choosing appropriate monomers, these cationic polymers can form core-shell micelles. These polymers exhibited biocidal activity against both Gram-positive and Gram-negative bacterial species. It is demonstrated that the micelles can deliver hydrophobic antibiotics that functionally have dual antimicrobial activities. Cytotoxicity assays against HeLa cells showed dosage-dependent toxicity for polymers with longer linkers.
Nearly Defect-Free Dynamical Models Of Disordered Solids: The Case Of Amorphous Silicon, Raymond Atta-Fynn, Parthapratim Biswas
Nearly Defect-Free Dynamical Models Of Disordered Solids: The Case Of Amorphous Silicon, Raymond Atta-Fynn, Parthapratim Biswas
Faculty Publications
It is widely accepted in the materials modeling community that defect-free realistic networks of amorphous silicon cannot be prepared by quenching from a molten state of silicon using classical or ab initio molecular-dynamics (MD) simulations. In this work, we address this long-standing problem by producing nearly defect-free ultra-large models of amorphous silicon, consisting of up to half a million atoms, using classical MD simulations. The structural, topological, electronic, and vibrational properties of the models are presented and compared with experimental data. A comparison of the models with those obtained from using the modified Wooten-Winer-Weaire bond-switching algorithm shows that the models …
Small-Angle X-Ray Scattering In Amorphous Silicon: A Computational Study, Durga Paudel, Raymond Atta-Fynn, David A. Drabold, Stephen R. Elliott, Parthapratim Biswas
Small-Angle X-Ray Scattering In Amorphous Silicon: A Computational Study, Durga Paudel, Raymond Atta-Fynn, David A. Drabold, Stephen R. Elliott, Parthapratim Biswas
Faculty Publications
We present a computational study of small-angle x-ray scattering (SAXS) in amorphous silicon (α-Si) with particular emphasis on the morphology and microstructure of voids. The relationship between the scattering intensity in SAXS and the three-dimensional structure of nanoscale inhomogeneities or voids is addressed by generating large high-quality (α-Si networks with 0.1%–0.3% volume concentration of voids, as observed in experiments using SAXS and positron annihilation spectroscopy. A systematic study of the variation of the scattering intensity in the small-angle scattering region with the size, shape, number density, and the spatial distribution of the voids in the networks is presented. Our results …
The Meniscus-Guided Deposition Of Semiconducting Polymers, Xiaodan Gu, Leo Shaw, Kevin Gu, Michael F. Toney, Zhenan Bao
The Meniscus-Guided Deposition Of Semiconducting Polymers, Xiaodan Gu, Leo Shaw, Kevin Gu, Michael F. Toney, Zhenan Bao
Faculty Publications
The electronic devices that play a vital role in our daily life are primarily based on silicon and are thus rigid, opaque, and relatively heavy. However, new electronics relying on polymer semiconductors are opening up new application spaces like stretchable and self-healing sensors and devices, and these can facilitate the integration of such devices into our homes, our clothing, and even our bodies. While there has been tremendous interest in such technologies, the widespread adoption of these organic electronics requires low-cost manufacturing techniques. Fortunately, the realization of organic electronics can take inspiration from a technology developed since the beginning of …
Expansion Of The (Bb)>Ru Metallacycle With Coinage Metal Cations: Formation Of B-M-Ru-B (M= Cu, Ag, Au) Dimetalacyclodiboryls†, Bennett J. Eleazer, Mark D. Smith, Alexey A. Popov, Dmitry V. Peryshkov
Expansion Of The (Bb)>Ru Metallacycle With Coinage Metal Cations: Formation Of B-M-Ru-B (M= Cu, Ag, Au) Dimetalacyclodiboryls†, Bennett J. Eleazer, Mark D. Smith, Alexey A. Popov, Dmitry V. Peryshkov
Faculty Publications
In this work, we introduce a novel approach for the selective assembly of heterometallic complexes by unprecedented coordination of coinage metal cations to strained single ruthenium–boron bonds on a surface of icosahedral boron clusters. M(I) cations (M ¼ Cu, Ag, and Au) insert into B–Ru bonds of the (BB)–carboryne complex of ruthenium with the formation of four-membered B–M–Ru–B metalacycles. Results of theoretical calculations suggest that bonding within these metalacycles can be best described as unusual three-center-two-electron B–M/Ru interactions that are isolobal to B–H/Ru borane coordination for M ¼ Cu and Ag, or the pairs of two-center-two electron B–Au and Au–Ru …
Adsorption Of Tnt, Dnan, Nto, Fox7, And Nq Onto Cellulose, Chitin, And Cellulose Triacetate. Insights From Density Functional Theory Calculations, Guido Todde, Sanjiv K. Jha, Gopinath Subramanian, Manoj K. Shula
Adsorption Of Tnt, Dnan, Nto, Fox7, And Nq Onto Cellulose, Chitin, And Cellulose Triacetate. Insights From Density Functional Theory Calculations, Guido Todde, Sanjiv K. Jha, Gopinath Subramanian, Manoj K. Shula
Faculty Publications
Insensitive munitions (IM) compounds such as DNAN (2,4-dinitroanisole), NTO (3-nitro-1,2,4-triazol-5-one), NQ (nitroguanidine), and FOX7 (1,1-diamino-2,2-dinitroethene) reduce the risk of accidental explosions due to shock and high temperature exposure. These compounds are being used as replacements for sensitive munition compounds such as TNT (2,4,6-trinitromethylbenzene) and RDX (1,3,5-hexahydro-1,3,5-trinitro-1,3,5-triazine). NTO and NQ in IM compounds are more soluble than TNT or RDX, hence they can easily spread in the environment and get dissolved if exposed to precipitation. DNAN solubility is comparable to TNT solubility. Cellulosic biomass, due to its abundance in the environment and its chemical structure, has a high probability of adsorbing …