Other Chemistry Commons^™

Toward The Probing Of Dhqs Activity By Protein Engineering Through The Introduction Of Unnatural Amino Acids And The Selection Of Trna/Trna Synthetase Pairs, Shaina E. Ives

Department of Chemistry: Dissertations, Theses, and Student Research

Protein engineering is a valuable tool that allows scientist to explore how an enzyme works by mutation of key residues. This method has been used to improve function or stability of enzymes, thus allowing their use in both the lab and in industry to be expanded. Genetic incorporation of unnatural amino acids (unAA) can be used with protein engineering to exceed the current limitations, due to the limited number of functional groups of the 20 common amino acids.

The majority of this thesis will discuss the progress on incorporating the various unAA into the active site of the enzyme, Dehydroquinate …

Photothermally Induced Optical Property Changes Of Poly (N-Isopropylacrylamide) Microgel-Based Etalons, Molla R. Islam, Jessica Irvine, Michael J. Serpe

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Poly(N-isopropylacrylamide) microgel-based optical devices were designed such that they can be stimulated to change their optical properties in response to light produced by a light-emitting diode (LED). The devices were fabricated by sandwiching the synthesized microgels between two Cr/Au layers all supported on a glass coverslip with gold nanoparticles (AuNPs) deposited. Here, we found that these devices can be stimulated to change their optical properties when exposed to green LED light, which excites the AuNPs and increases the local temperature, causing the thermoresponsive microgels to decrease in diameter, resulting in a change in the devices’ optical properties. We also found …

Bis(Spirolactam) 1,3-Double-Armed Calix[4]Arene Compounds And Their Application As Extractants For The Determination Of Heavy Metal Ions, Fintan Kelleher, Mary Deasy, James Ward, Li Li, Fiona Regan

Articles

A number of double-armed calix[4]arene compounds, with proline-derived spirolactam ligating groups on the lower rim, have been synthesised and investigated as extractants of toxic heavy metal ions from aqueous solution. Pedersen’s extraction technique was employed to determine the capability of these new 1,3-distal derived calix[4]arene spiroalactams to extract selected heavy metal ions (e.g. Pb²⁺, Cd²⁺, Zn²⁺, Cu²⁺, Ni²⁺, Co²⁺) from an aqueous phase into an organic phase. The percentage extraction was calculated using UV-vis spectroscopy. All of the compounds synthesised demonstrated good selectivity for the heavy metals selected …

Electrochemical Characterization Of Protein Adsorption Onto Yngrt-Au And Vlgxe-Au Surfaces, Hanna Trzeciakiewicz, Jose Esteves-Villanueva, Rania Soudy, Kamaljit Kaur, Sanela Martic-Milne

Pharmacy Faculty Articles and Research

The adsorption of the proteins CD13, mucin and bovine serum albumin on VLGXE-Au and YNGRT-Au interfaces was monitored by electrochemical impedance spectroscopy in the presence of [Fe(CN)6]3−/4−. The hydrophobicity of the Au surface was tailored using specific peptides, blocking agents and diluents. The combination of blocking agents (ethanolamine or n-butylamine) and diluents (hexanethiol or 2-mercaptoethanol) was used to prepare various peptide-modified Au surfaces. Protein adsorption onto the peptide-Au surfaces modified with the combination of n-butylamine and hexanethiol produced a dramatic decrease in the charge transfer resistance, Rct, for all three proteins. In contrast, polar peptide-surfaces induced a minimal change in …

Effect Of Surface Omniphobicity On Drying By Forced Convection, Madani A. Khan, Jeffrey Alston, Andrew Guenthner

STAR Program Research Presentations

Low energy surfaces can strongly repel both oil and water. Recently these surfaces have been fabricated on various substrates including fabric, aluminum, stainless steel and many other materials. In this experiment we explore the use of low energy surface deposition on aluminum alloy, stainless steel and silicon substrates, to enhance the drying rate of liquids removed from the surface by forced convection. We control surface roughness by substrate abrasion and by the growth of Al₂O₃ nanograss to enhance liquid repellence by use of a hierarchical texture. Liquid repellence of the substrates is measured by contact angles of …

Synthesis And Flammability Testing Of Epoxy Functionalized Phosphorous-Based Flame Retardants, Vladimir Benin, Xuemei Cui, Alexander Morgan, Karl Seiwert

Chemistry Faculty Publications

Several potential new phosphorus-containing flame retardant molecules were evaluated for heat release reduction potential by incorporation of the molecules into a polyurethane, generated from methylene diphenyl diisocyanate and 1,3-propane diol. The heat release reduction potential of these substances was evaluated using the pyrolysis combustion flow calorimeter (PCFC). The polyurethanes were prepared in the presence of the potential flame retardants via solvent mixing and copolymerization methods to qualitatively evaluate their potential reactivity into the polyurethane prior to heat release testing. The functionality of the flame retardants was epoxide based that would potentially react with the diol during polyurethane synthesis. Flammability testing …

Thz-Pulse-Induced Selective Catalytic Co Oxidation On Ru, Jerry L. Larue, Tetsuo Katayama, Aaron Lindenberg, Alan S. Fisher, Henrik Öström, Anders Nilsson, Hirohito Ogasawara

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

We demonstrate the use of intense, quasi-half-cycle THz pulses, with an associated electric field component comparable to intramolecular electric fields, to direct the reaction coordinate of a chemical reaction by stimulating the nuclear motions of the reactants. Using a strong electric field from a THz pulse generated via coherent transition radiation from an ultrashort electron bunch, we present evidence that CO oxidation on Ru(0001) is selectively induced, while not promoting the thermally induced CO desorption process. The reaction is initiated by the motion of the O atoms on the surface driven by the electric field component of the THz pulse, …

Mangiferin As A Biomarker For Mango Anthracnose Resistance, Herma Pierre

FIU Electronic Theses and Dissertations

Mangos (Mangifera indica L.) are tropical/subtropical fruits belonging to the plant family Anacardiaceae. Anthracnose is the most deleterious disease of mango both in the field and during postharvest handling. It is most commonly caused by the Colletotrichum gloeosporioides complex. Mangiferin, a xanthanoid compound found in at least twelve plant families worldwide (Luo et al., 2012), is present in large amounts of the leaves and edible mangos. Even though this compound plays a pivotal role in the plant’s defense against biotic and abiotic stressors, no correlations been made between the compound and mango anthracnose resistance.

Mangos were collected, grouped …

The Best Of Both Worlds: Building On The Copus And Rtop Observation Protocols To Easily And Reliably Measure Various Levels Of Reformed Instructional Practice, Travis J. Lund, Matthew Pilarz, Jonathan B. Velasco, Devasmita Chakraverty, Kaitlyn Rosploch, Molly Undersander, Marilyne Stains

Chemistry Department: Faculty Publications

Researchers, university administrators, and faculty members are increasingly interested in measuring and describing instructional practices provided in science, technology, engineering, and mathematics (STEM) courses at the college level. Specifically, there is keen interest in comparing instructional practices between courses, monitoring changes over time, and mapping observed practices to research-based teaching. While increasingly common observation protocols (Reformed Teaching Observation Protocol [RTOP] and Classroom Observation Protocol in Undergraduate STEM [COPUS]) at the postsecondary level help achieve some of these goals, they also suffer from weaknesses that limit their applicability. In this study, we leverage the strengths of these protocols to provide an …

Analysis Of Synthetic Cannabinoids By Direct Analysis In Real Time Quadrupole Time-Of-Flight Mass Spectrometry And Gas Chromatography Quadrupole Time-Of-Flight Mass Spectrometry, Tyler S. Torbet

FIU Electronic Theses and Dissertations

The aim of this study was to investigate the utility of direct analysis in real time quadrupole time-of-flight mass spectrometry and gas chromatography quadrupole time-of-flight mass spectrometry in the analysis of 162 different synthetic cannabinoids. Direct analysis in real time quadrupole time-of-flight mass spectrometry is shown to be a rapid and accurate analytical method for synthetic cannabinoids. Spectra can be generated with less than 1.5 ng of the drug in under a minute and be successfully searched against previously generated ESI-QTOF libraries in most cases (118/130 drugs tested) as well as can also be applied to the identification of synthetic …

A Multilaboratory Comparison Of Calibration Accuracy And The Performance Of External References In Analytical Ultracentrifugation, Huaying Zhao, Rodolfo Ghirlando, Carlos Alfonso, Fumio Arisaka, Ilan Attali, David L. Bain, Et Al. ..., Donald F. Becker, Peter Schuck

Department of Biochemistry: Faculty Publications

Analytical ultracentrifugation (AUC) is a first principles based method to determine absolute sedimentation coefficients and buoyant molar masses of macromolecules and their complexes, reporting on their size and shape in free solution. The purpose of this multi-laboratory study was to establish the precision and accuracy of basic data dimensions in AUC and validate previously proposed calibration techniques. Three kits of AUC cell assemblies containing radial and temperature calibration tools and a bovine serum albumin (BSA) reference sample were shared among 67 laboratories, generating 129 comprehensive data sets. These allowed for an assessment of many parameters of instrument performance, including accuracy …

Green Chemistry As A Tool For Understanding The Toxic Substances Control Act: A Lecture Module For Undergraduate Students, Molly R. Blessing

Honors Scholar Theses

The Toxic Substances Control Act (TSCA) is the central form of chemical regulation existent in the United States today, yet scientists are often unaware or uncertain of its provisions. Violations of TSCA by unknowing chemists set industry and government unnecessarily at odds. A lecture on TSCA was developed for undergraduate students that uses the concept of green chemistry to promote interest and incentivize learning. Green chemistry methods are cleaner and less wasteful than traditional chemical ones, and many companies using them are at the forefront of technological innovation. The lecture explains both green chemistry and TSCA, includes company case studies, …

Investigations Into The Molecular Mechanisms Of Bacterial Pathogen-Host Interactions: Construction Of A Dual Plasmid System For Incorporation Of Unnatural Amino Acids Into Pseudomonas Syringae Pv. Tomato Dc3000, Scotty D. Raber

Department of Chemistry: Dissertations, Theses, and Student Research

A dual plasmid system for the incorporation of unnatural amino acids into plant pathogen, Pseudomonas syringae pv. tomato DC3000, has been designed. This invention is expected to allow (a) mutations of proteins synthesized by the bacterium, P. syringae pv. tomato DC3000, that can capture molecular targets, especially for such modified proteins secreted by the phytopathogen into the host plant cells of A. thaliana and S. lycopersicum, (b) expression of biological probes in the bacterial species to monitor changes in redox, nutritional, and other small molecule states over pre-, post- and in situ disease stages, and (c) secretion of such …

A Maltose-Binding Protein Fusion Construct Yields A Robust Crystallography Platform For Mcl1, Matthew C. Clifton, David M. Dranow, Alison Leed, Ben Fulroth, James W. Fairman, Jan Abendroth, Kateri A. Atkins, Ellen Wallace, Dazhong Fan, Guoping Xu, Z. J. Ni, Douglas S. Daniels, John Van Drie, Guo Wei, Alex B. Burgin, Todd R. Golub, Brian K. Hubbard, Michael H. Serrano-Wu

Chemistry Faculty Publications

Crystallization of a maltose-binding protein MCL1 fusion has yielded a robust crystallography platform that generated the first apo MCL1 crystal structure, as well as five ligand-bound structures. The ability to obtain fragment-bound structures advances structure-based drug design efforts that, despite considerable effort, had previously been intractable by crystallography. In the ligand-independent crystal form we identify inhibitor binding modes not observed in earlier crystallographic systems. This MBP-MCL1 construct dramatically improves the structural understanding of well-validated MCL1 ligands, and will likely catalyze the structure-based optimization of high affinity MCL1 inhibitors.

Strong Influence Of Coadsorbate Interaction On Co Desorption Dynamics On Ru(0001) Probed By Ultrafast X-Ray Spectroscopy And Ab Initio Simulations, H. Xin, Jerry L. Larue, H. Öberg, M. Beye, M. Dell'angela, J. J. Turner, J. Gladh, M. L. Ng, J. A. Sellberg, S. Kaya, G. Mercurio, F. Hieke, D. Nordlund, W. F. Schlotter, G. L. Dakovski, M. P. Minitti, A. Föhlisch, M. Wolf, W. Wurth, H. Ogasawara, J. K. Nørskov, H. Öström, L. G. M. Pettersson, A. Nilsson, F. Abild-Pedersen

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

We show that coadsorbed oxygen atoms have a dramatic influence on the CO desorption dynamics from Ru(0001). In contrast to the precursor-mediated desorption mechanism on Ru(0001), the presence of surface oxygen modifies the electronic structure of Ru atoms such that CO desorption occurs predominantly via the direct pathway. This phenomenon is directly observed in an ultrafast pump-probe experiment using a soft x-ray free-electron laser to monitor the dynamic evolution of the valence electronic structure of the surface species. This is supported with the potential of mean force along the CO desorption path obtained from density-functional theory calculations. Charge density distribution …

Optical Laser-Induced Co Desorption From Ru(0001) Monitored With A Free-Electron X-Ray Laser: Dft Prediction And X-Ray Confirmation Of A Precursor State, H. Öberg, J. Gladh, M. Dell'angela, T. Anniyev, M. Beye, R. Coffee, A. Föhlisch, T. Katayama, S. Kaya, Jerry L. Larue, A. Møgelhøj, D. Nordlund, H. Ogasawara, W. F. Schlotter, J. A. Sellberg, F. Sorgenfrei, J. J. Turner, M. Wolf, W. Wurth, H. Öström, A. Nilsson, J. K. Nørskov, L. G. M. Pettersson

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

We present density functional theory modeling of time-resolved optical pump/X-ray spectroscopic probe data of CO desorption from Ru(0001). The BEEF van der Waals functional predicts a weakly bound state as a precursor to desorption. The optical pump leads to a near-instantaneous (< 100 fs) increase of the electronic temperature to nearly 7000 K. The temperature evolution and energy transfer between electrons, substrate phonons and adsorbate is described by the two-temperature model and found to equilibrate on a timescale of a few picoseconds to an elevated local temperature of ~ 2000 K. Estimating the free energy based on the computed potential of mean force along the desorption path, we find an entropic barrier to desorption (and by time-reversal also to adsorption). This entropic barrier separates the chemisorbed and precursor states, and becomes significant at the elevated temperature of the experiment (~ 1.4 eV at 2000 K). Experimental pump-probe X-ray absorption/X-ray emission spectroscopy indicates population of a precursor state to desorption upon laser-excitation of the system (Dell'Angela et al., 2013). Computing spectra along the desorption path confirms the picture of a weakly bound transient state arising from ultrafast heating of the metal substrate.

Delay Line As A Chemical Reaction Network, Josh Moles, Peter Banda, Christof Teuscher

Computer Science Faculty Publications and Presentations

Chemistry as an unconventional computing medium presently lacks a systematic approach to gather, store, and sort data over time. To build more complicated systems in chemistries, the ability to look at data in the past would be a valuable tool to perform complex calculations. In this paper we present the first implementation of a chemical delay line providing information storage in a chemistry that can reliably capture information over an extended period of time. The delay line is capable of parallel operations in a single instruction, multiple data (SIMD) fashion.

Using Michaelis-Menten kinetics, we describe the chemical delay line implementation …

Probing The Transition State Region In Catalytic Co Oxidation On Ru, H. Öström, H. Öberg, H. Xin, Jerry L. Larue, M. Beye, M. Dell'angela, J. Gladh, M. L. Ng, J. A. Sellberg, S. Kaya, G. Mercurio, D. Nordlund, M. Hantschmann, F. Hieke, D. Kühn, W. F. Schlotter, G. L. Dakovski, J. J. Turner, M. P. Minitti, A. Mitra, S. P. Moeller, A. Föhlisch, M. Wolf, W. Wurth, M. Persson, J. K. Nørskov, F. Abild-Pedersen, H. Ogasawara, L. G. M. Pettersson, A. Nilsson

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Femtosecond x-ray laser pulses are used to probe the CO oxidation reaction on Ru initiated by an optical laser pulse. On a timescale of a few hundred femtoseconds, the optical laser pulse excites motions of CO and O on the surface allowing the reactants to collide and, with a transient close to a picosecond (ps), new electronic states appear in the O K-edge x-ray absorption spectrum. Density functional theory calculations indicate that these result from changes in the adsorption site and bond-formation between CO and O with a distribution of OC—O bond lengths close to the transition state (TS). After …

Research-Based Implementation Of Peer Instruction: A Literature Review, Trisha Vickrey, Kaitlyn Rosploch, Reihaneh Rahmanian, Matthew Pilarz, Marilyne Stains

Chemistry Department: Faculty Publications

Current instructional reforms in undergraduate science, technology, engineering, and mathematics (STEM) courses have focused on enhancing adoption of evidence-based instructional practices among STEM faculty members. These practices have been empirically demonstrated to enhance student learning and attitudes. However, research indicates that instructors often adapt rather than adopt practices, unknowingly compromising their effectiveness. Thus, there is a need to raise awareness of the research-based implementation of these practices, develop fidelity of implementation protocols to understand adaptations being made, and ultimately characterize the true impact of reform efforts based on these practices. Peer instruction (PI) is an example of an evidence-based instructional …

New Insight Into The Helium-Induced Damage In Max Phase Ti3Alc2 By First-Principles Studies, Yiguo Xu, Xiaojing Bai, Xianhu Zha, Qing Huang, Jian He, Kan Luo, Yuhong Zhou, Timothy C. Germann, Joseph S. Francisco, Shiyu Du

Chemistry Department: Faculty Publications

In the present work, the behavior of He in the MAX phase Ti3AlC2 material is investigated using first-principle methods. It is found that, according to the predicted formation energies, a single He atom favors residing near the Al plane in Ti3AlC2. The results also show that Al vacancies are better able to trap He atoms than either Ti or C vacancies. The formation energies for the secondary vacancy defects near an Al vacancy or a C vacancy are strongly influenced by He impurity content. According to the present results, the existence of trapped He atoms in primary Al vacancy can …

Communication: Spectroscopic Consequences Of Proton Delocalization In Ochco+, Ryan C. Fortenberry, Qi Yu, John S. Mancini, Joel M. Bowman, Timothy J. Lee, T. Daniel Crawford, William F. Klemperer, Joseph S. Francisco

Chemistry Department: Faculty Publications

Even though quartic force fields (QFFs) and highly accurate coupled cluster computations describe the OCHCO⁺ cation at equilibrium as a complex between carbon monoxide and the formyl cation, two notable and typical interstellar and atmospheric molecules, the prediction from the present study is that the equilibrium C_∞v structure is less relevant to observables than the saddle-point D_∞h structure. This is the conclusion from diffusion Monte Carlo and vibrational self-consistent field/virtual state configuration interaction calculations utilizing a semi-global potential energy surface. These calculations demonstrate that the proton “rattle” motion (ν₆) has centrosymmetric delocalization of the …

Structural And Optical Properties Of Cobalt Slanted Nanopillars Conformally Coated With Few-Layer Graphene, Peter M. Wilson, Alexey Lipatov, Daniel Schmidt, Eva Schubert, Mathias Schubert, Alexander Sinitskii, Tino Hofmann

Chemistry Department: Faculty Publications

Optical characterization of anisotropic multicomponent nanostructures is generally not a trivial task, since the relation between a material’s structural properties and its permittivity tensor is nonlinear. In this regard, an array of slanted cobalt nanopillars that are conformally coated with few-layer graphene is a particularly challenging object for optical characterization, as it has a complex anisotropic geometry and comprises several materials with different topologies and filling fractions. Normally, a detailed characterization of such complex nanostructures would require a combination of several microscopic and spectroscopic techniques. In this letter, we demonstrate that the important structural parameters of these graphene-coated sculptured thin …

A Comparison Of Energy-Resolved Vibrational Activation/Dissociation Characteristics Of Protonated And Sodiated High Mannose N-Glycopeptides, Forouzan Aboufazeli, Venkata Kolli, Eric D. Dodds

Chemistry Department: Faculty Publications

Fragmentation of glycopeptides in tandem mass spectrometry (MS/MS) plays a pivotal role in site-specific protein glycosylation profiling by allowing specific oligosaccharide compositions and connectivities to be associated with specific loci on the corresponding protein. Although MS/MS analysis of glycopeptides has been successfully performed using a number of distinction dissociation methods, relatively little is known regarding the fragmentation characteristics of glycopeptide ions with various charge carriers. In this study, energy-resolved vibrational activation/ dissociation was examined via collision-induced dissociation for a group of related high mannose tryptic glycopeptides as their doubly protonated, doubly sodiated, and hybrid protonated sodium adduct ions. The doubly …

The Importance Of Context: An Exploration Of Factors Influencing The Adoption Of Student-Centered Teaching Among Chemistry, Biology, And Physics Faculty, Travis J. Lund, Marilyne Stains

Chemistry Department: Faculty Publications

Background: Research at the secondary and postsecondary levels has clearly demonstrated the critical role that individual and contextual characteristics play in instructors’ decision to adopt educational innovations. Although recent research has shed light on factors influencing the teaching practices of science, technology, engineering, and mathematics (STEM) faculty, it is still not well understood how unique departmental environments impact faculty adoption of evidence-based instructional practices (EBIPs) within the context of a single institution. In this study, we sought to characterize the communication channels utilized by STEM faculty, as well as the contextual and individual factors that influence the teaching practices …

Hfq Regulates Antibacterial Antibiotic Biosynthesis And Extracellular Lytic-Enzyme Production In Lysobacter Enzymogenes Oh11, Gaoge Xu, Yuxin Zhao, Liangcheng Du, Guoliang Qian, Fengquan Liu

Chemistry Department: Faculty Publications

Lysobacter enzymogenes is an important biocontrol agent with the ability to produce a variety of lytic enzymes and novel antibiotics. Little is known about their regulatory mechanisms. Understanding these will be helpful for improving biocontrol of crop diseases and potential medical application. In the present study, we generated an hfq (encoding a putative ribonucleic acid chaperone) deletion mutant, and then utilized a new genomic marker-free method to construct an hfq-complemented strain. We showed for the first time that Hfq played a pleiotropic role in regulating the antibacterial antibiotic bio- synthesis and extracellular lytic enzyme activity in L. enzymogenes. Mutation of …

Energetics, Structure, And Rovibrational Spectroscopic Properties Of The Sulfurous Anions Sno− And Osn−, Ryan C. Fortenberry, Joseph S. Francisco

Chemistry Department: Faculty Publications

The SNO⁻ and OSN⁻ anions are shown in this work to be very stable negatively charged species in line with other recent work [T. Trabelsi et al., J. Chem. Phys. 143, 164301 (2015)]. Utilizing established quartic force field techniques, the structural and rovibrational data for these anions are produced. The SNO⁻ anion is less linear and has weaker bonds than the corresponding neutral radical giving much smaller rotational constants.OSN⁻ is largely unchanged in these regards with inclusion of the additional electron.The S–N bond is actually stronger,and the rotational constants of OSN⁻ versus OSN are …

Biotechnological Production Of 1,2,4-Butanetriol: An Efficient Process To Synthesize Energetic Material Precursor From Renewable Biomass, Yujin Cao, Wei Niu, Jiantao Guo, Mo Xian, Huizhou Liu

Chemistry Department: Faculty Publications

1,2,4-Butanetriol (BT) is a valuable chemical with extensive applications in many different fields. The traditional chemical routes to synthesize BT suffer from many drawbacks, e.g., harsh reaction conditions, multiple steps and poor selectivity, limiting its industrial production. In this study, an engineered Escherichia coli strain was constructed to produce BT from xylose, which is a major component of the lignocellulosic biomass. Through the coexpression of a xylose dehydrogenase (CCxylB) and a xylonolactonase (xylC) from Caulobacter crescentus, native E. coli xylonate dehydratase (yjhG), a 2-keto acid decarboxylase from Pseudomonas putida (mdlC) and …

Recyclable Magnetite Nanoparticle Catalyst For One-Pot Conversion Of Cellobiose To 5-Hydroxymethylfurfural In Water, Anuja Bhalkikar, Zane C. Gernhart, Chin Li Cheung

Chemistry Department: Faculty Publications

Environmentally benign and easily recoverable magnetite nanoparticles (Fe₃O₄ NPs) were demonstrated to catalyze the one-pot conversion of cellobiose, a glucose disaccharide, to 5-hydroxymethylfurfural (5-HMF).Theconversion was achieved in water under hydrothermal conditions.The catalytic activity of Fe₃O₄ NPs surpassed those of iron (II) and iron (III) chlorides in this reaction. Optimized cellobiose conversion reactions catalyzed with Fe₃O₄ NPs gave the highest 5-HMF yields of 23.4 ± 0.6% at 160^∘C for 24 hours. After three reuses, the Fe₃O₄ NP catalyst retained its catalytic activity with similar 5-HMF yields, demonstrating …

Stretchable Conductive Composites For Use In Soft Devices, Joshua Aaron Lessing, Stephen A. Morin, George M. Whitesides

Chemistry Department: Faculty Publications

An elastically-deformable, conductive composite using elastomers and conductive fibers and simple fabrication procedures is provided. Conductive elastomeric composites offer low resistance to electrical current and are elastic over large (>25%) extensional strains. They can be easily interfaced/built into structures fabricated from elastomeric polymers.

Simulation Evidence Of Hexagonal-To-Tetragonal Znse Structure Transition: A Monolayer Material With A Wide-Range Tunable Direct Bandgap, Lei Li, Pengfei Li, Ning Lu, Jun Dai, Xiao Cheng Zeng

Chemistry Department: Faculty Publications

2D material with tunable direct bandgap in the intermediate region (i.e., ≈2–3 eV) is key to the achievement of high efficiency in visible-light optical devices. Herein, a simulation evidence of structure transition of monolayer ZnSe from the experimental pseudohexagonal structure to the tetragonal structure (t-ZnSe) under lateral pressure is shown, suggesting a possible fabrication route to achieve the t-ZnSe monolayer. The as-produced t-ZnSe monolayer exhibits highly tunable bandgap under the biaxial strains, allowing strain engineering of t-ZnSe’s bandgap over a wide range of 2–3 eV. Importantly, even under the biaxial strain up to 7%, the t-ZnSe monolayer still keeps its …