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Full-Text Articles in Physical Sciences and Mathematics

Periodic Tabletalks: The Elements Never Go Out Of Style, Javier Vela, Emily A. Weiss Apr 2021

Periodic Tabletalks: The Elements Never Go Out Of Style, Javier Vela, Emily A. Weiss

Chemistry Publications

With the cancelation of the Spring ACS National meeting in 2020—and subsequent in-person meetings—because of the COVID-19 pandemic, the Division of Inorganic Chemistry (DIC) sought new ways to connect with its membership and continue to showcase the fantastic research carried out by inorganic chemists. The DIC executive committee thus initiated monthly Zoom webinars with two speakers each, typically one junior investigator and one more-established researcher, selected with input from each of the DIC subdivisions: Bioinorganic, Coordination, Solid-State, Organometallic, Nanoscience, and Sustainable Energy & Environment.


Detection Of Gold Cysteine Thiolate Complexes On Gold Nanoparticles With Time-Of-Flight Secondary Ion Mass Spectrometry, Yolanda Hedberg, Jonas Hedberg, Valentin Romanovski, Elena Romanovskaia, Heng-Yong Nie Apr 2021

Detection Of Gold Cysteine Thiolate Complexes On Gold Nanoparticles With Time-Of-Flight Secondary Ion Mass Spectrometry, Yolanda Hedberg, Jonas Hedberg, Valentin Romanovski, Elena Romanovskaia, Heng-Yong Nie

Chemistry Publications

Gold (Au) nanoparticles (NPs) are widely used in nanomedical applications as a carrier for molecules designed for different functionalities. Previous findings suggested that biological molecules, including amino acids, could contribute to the dissolution of Au NPs in physiological environments and that this phenomenon was size-dependent. We, therefore, investigated the interactions of L-cysteine with 5-nm Au NPs by means of time-of-flight secondary ion mass spectrometry (ToF-SIMS). This was achieved by loading Au NPs on a clean aluminum (Al) foil and immersing it in an aqueous solution containing L-cysteine. Upon rinsing off the excessive cysteine molecules, ToF-SIMS confirmed the formation of gold ...


Localization Of Nonblinking Point Sources Using Higher-Order-Mode Detection And Optical Heterodyning: Developing A Strategy For Extending The Scope Of Molecular, Super-Resolution Imaging, Kaylan Santra, Viet Nguyen, Emily A. Smith, Jacob W. Petrich, Xueyu Song Mar 2021

Localization Of Nonblinking Point Sources Using Higher-Order-Mode Detection And Optical Heterodyning: Developing A Strategy For Extending The Scope Of Molecular, Super-Resolution Imaging, Kaylan Santra, Viet Nguyen, Emily A. Smith, Jacob W. Petrich, Xueyu Song

Chemistry Publications

While the stochastic, “blinking” nature of fluorescent systems has enabled the super-resolution of their localization by the fitting of their point-spread functions (PSFs), this strategy cannot be exploited for similar resolution of “nonblinking” systems, such as those that might be encountered in a coherent Raman experiment. An alternative method for subdiffraction-limited imaging lies in the exploitation of optical heterodyning. For example, if a Gaussian PSF (a TEM00 mode) of a point emitter is displaced with respect to the origin of the optical system, photons in the higher-order TEM modes carry information about that displacement. Information concerning the displacement can be ...


A Systematic Way To Extend The Debye–Hückel Theory Beyond Dilute Electrolyte Solutions, Tiejun Xiao, Xueyu Song Mar 2021

A Systematic Way To Extend The Debye–Hückel Theory Beyond Dilute Electrolyte Solutions, Tiejun Xiao, Xueyu Song

Chemistry Publications

An extended Debye–Hückel theory with fourth order gradient term is developed for electrolyte solutions; namely, the electric potential φ(r) of the bulk electrolyte solution can be described by ∇2φ(r) = κ2φ(r) + LQ2∇4φ(r), where the parameters κ and LQ are chosen to reproduce the first two roots of the dielectric response function of the bulk solution. Three boundary conditions for solving the electric potential problem are proposed based upon the continuity conditions of involving functions at the dielectric boundary, with which a boundary element method for the electric potential of a solute with ...


Sequence‐Selective Protection Of Peptides From Proteolysis, Xiaowei Li, Kaiqian Chen, Yan Zhao Mar 2021

Sequence‐Selective Protection Of Peptides From Proteolysis, Xiaowei Li, Kaiqian Chen, Yan Zhao

Chemistry Publications

Proteolysis of proteins and peptides is involved in the infection of cells by enveloped viruses and also in the invasion and spread of cancer cells. Shutting down broad‐specificity proteases, however, is problematic because normal functions by these proteases will be affected. Herein, nanoparticle receptors were prepared from molecular imprinting for complex biological peptides. Their strong and selective binding enabled them to protect their targeted sequences from proteolysis in aqueous solution at stoichiometric amounts. Generality of the method was demonstrated by the protection of hydrophobic and hydrophilic peptides from different proteases, selective protection of a segment of a long peptide ...


Energy Spotlight: Advances In Lib Electrolyte, Stabilizing Cspbbr3 In Mesoporous Silica, And Halide Segregation In Mixed Halide Perovskites, Nam-Soon Choi, Javier Vela, Jeffrey Dubose, Prashant V. Kamat Mar 2021

Energy Spotlight: Advances In Lib Electrolyte, Stabilizing Cspbbr3 In Mesoporous Silica, And Halide Segregation In Mixed Halide Perovskites, Nam-Soon Choi, Javier Vela, Jeffrey Dubose, Prashant V. Kamat

Chemistry Publications

One of the biggest developments of the past decade in the field of colloidal semiconductors is the introduction of lead halide perovskite nanocrystals. Because of their low cost, ease of synthesis, and near ideal optical properties, these materials are versatile building blocks for light-emitting displays, solar cells, environmental sensors, and radiation detectors.


Noncentrosymmetric Tetrel Pnictides Rusi4p4 And Irsi3p3: Nonlinear Optical Materials With Outstanding Laser Damage Threshold, Shannon Lee, Scott L. Carnahan, Georgiy Akopov, Philip Yox, Lin-Lin Wang, Aaron J. Rossini, Kui Wu, Kirill Kovnir Feb 2021

Noncentrosymmetric Tetrel Pnictides Rusi4p4 And Irsi3p3: Nonlinear Optical Materials With Outstanding Laser Damage Threshold, Shannon Lee, Scott L. Carnahan, Georgiy Akopov, Philip Yox, Lin-Lin Wang, Aaron J. Rossini, Kui Wu, Kirill Kovnir

Chemistry Publications

Noncentrosymmetric (NCS) tetrel pnictides have recently generated interest as nonlinear optical (NLO) materials due to their second harmonic generation (SHG) activity and large laser damage threshold (LDT). Herein nonmetal‐rich silicon phosphides RuSi4P4 and IrSi3P3 are synthesized and characterized. Their crystal structures are reinvestigated using single crystal X‐ray diffraction and 29Si and 31P magic angle spinning NMR. In agreement with previous report RuSi4P4 crystallizes in NCS space group P1, while IrSi3P3 is found to crystallize in NCS space group Cm, in contrast with the previously reported space group C2. A combination of DFT calculations and diffuse reflectance ...


Welding Fume Nanoparticles From Solid And Flux-Cored Wires: Solubility, Toxicity, And Role Of Fluorides, Yolanda S. Hedberg, Z. Wei, S. Mccarrick, V. Romanovski, J. Theodore, E. M. Westin, R. Wagner, K.-A. Persson, H. L. Karlsson, I. Odnevall Wallinder Feb 2021

Welding Fume Nanoparticles From Solid And Flux-Cored Wires: Solubility, Toxicity, And Role Of Fluorides, Yolanda S. Hedberg, Z. Wei, S. Mccarrick, V. Romanovski, J. Theodore, E. M. Westin, R. Wagner, K.-A. Persson, H. L. Karlsson, I. Odnevall Wallinder

Chemistry Publications

Welding fume particles are hazardous. Their toxicity likely depends on their composition and reactivity. This study aimed at exploring the role of sodium or other fluorides (NaF), which are intentionally added to flux-cored wire electrodes for stainless steel welding, on the solubility (in phosphate buffered saline) and toxicity of the generated welding fume particles. A multi-analytical particle characterization approach along with in-vitro cell assays was undertaken. The release of Cr(VI) and Mn from the particles was tested as a function of fluoride solution concentration. The welding fume particles containing NaF released significantly higher amounts of Cr(VI) compared with ...


The Surface Chemistry And Structure Of Colloidal Lead Halide Perovskite Nanocrystals, Sara R. Smock, Yunhua Chen, Aaron J. Rossini, Richard L. Brutchey Feb 2021

The Surface Chemistry And Structure Of Colloidal Lead Halide Perovskite Nanocrystals, Sara R. Smock, Yunhua Chen, Aaron J. Rossini, Richard L. Brutchey

Chemistry Publications

Since the initial discovery of colloidal lead halide perovskite nanocrystals, there has been significant interest placed on these semiconductors because of their remarkable optoelectronic properties, including very high photoluminescence quantum yields, narrow size- and composition-tunable emission over a wide color gamut, defect tolerance, and suppressed blinking. These material attributes have made them attractive components for next-generation solar cells, light emitting diodes, low-threshold lasers, single photon emitters, and X-ray scintillators. While a great deal of research has gone into the various applications of colloidal lead halide perovskite nanocrystals, comparatively little work has focused on the fundamental surface chemistry of these materials ...


Advances In Mutation Detection Using Loop-Mediated Isothermal Amplification, Marcelino Varona, Jared L. Anderson Jan 2021

Advances In Mutation Detection Using Loop-Mediated Isothermal Amplification, Marcelino Varona, Jared L. Anderson

Chemistry Publications

Detection of mutations and single-nucleotide polymorphisms is highly important for diagnostic applications. Loop-mediated isothermal amplification (LAMP) is a powerful technique for the rapid and sensitive detection of nucleic acids. However, LAMP traditionally does not possess the ability to resolve single-nucleotide differences within the target sequence. Because of its speed and isothermal nature, LAMP is ideally suited for point-of-care applications in resource-limited settings. Recently, different approaches have been developed and applied to enable single-nucleotide differentiation within target sequences. This Mini-Review highlights advancements in mutation detection using LAMP. Methods involving primer design and modification to enable sequence differentiation are discussed. In addition ...


Elucidating The Location Of Cd2+ In Post-Synthetically Treated Inp Quantum Dots Using Dynamic Nuclear Polarization 31p And 113cd Solid-State Nmr Spectroscopy, Michael P. Hanrahan, Jennifer L. Stein, Nayon Park, Brandi M. Cossairt, Aaron J. Rossini Jan 2021

Elucidating The Location Of Cd2+ In Post-Synthetically Treated Inp Quantum Dots Using Dynamic Nuclear Polarization 31p And 113cd Solid-State Nmr Spectroscopy, Michael P. Hanrahan, Jennifer L. Stein, Nayon Park, Brandi M. Cossairt, Aaron J. Rossini

Chemistry Publications

Indium phosphide quantum dots (InP QD) are a promising alternative to traditional QD materials that contain toxic heavy elements such as lead and cadmium. However, InP QD obtained from colloidal synthesis are often plagued by poor photoluminescence quantum yields (PL-QYs). In order to improve the PL-QY of InP QD, a number of post-synthetic treatments have been devised. Recently, it has been shown that InP post-synthetically treated with Lewis acid metal divalent cations (M-InP) exhibit enhanced PL-QY; however, the molecular structure and mechanism behind the improved PL-QY are not fully understood. To determine the surface structure of M-InP QD, dynamic nuclear ...


Metal Bioaccessibility In Synthetic Bodyfluids–A Way To Considerpositive And Negative Alloying Effects In Hazard Assessments, Yolanda S. Hedberg, Xuying Wang, James J. Noël, Inger Odnevall Wallinder Jan 2021

Metal Bioaccessibility In Synthetic Bodyfluids–A Way To Considerpositive And Negative Alloying Effects In Hazard Assessments, Yolanda S. Hedberg, Xuying Wang, James J. Noël, Inger Odnevall Wallinder

Chemistry Publications

Hazard classification of metal alloys is today generally based on their bulk content, an approach that seldom reflects the extent of metal release for a given environment. Such information can instead be achieved via bioelution testing under simulated physiological conditions. The use of bioelution data instead of bulk contents would hence refine the current hazard classification of alloys and enable grouping. Bioelution data have been generated for nickel (Ni) and cobalt (Co) released from several stainless steel grades, one low-alloyed steel, and Ni and Co metals in synthetic sweat, saliva and gastric fluid, for exposure periods from 2 to 168 ...


Synthetic Glycosidases For The Precise Hydrolysis Of Oligosaccharides And Polysaccharides, Xiaowei Li, Yan Zhao Jan 2021

Synthetic Glycosidases For The Precise Hydrolysis Of Oligosaccharides And Polysaccharides, Xiaowei Li, Yan Zhao

Chemistry Publications

Glycosidases are an important class of enzymes for performing the selective hydrolysis of glycans. Although glycans can be hydrolyzed in principle by acidic water, hydrolysis with high selectivity using nonenzymatic catalysts is an unachieved goal. Molecular imprinting in cross-linked micelles afforded water-soluble polymeric nanoparticles with a sugar-binding boroxole in the imprinted site. Post-modification installed an acidic group near the oxygen of the targeted glycosidic bond, with the acidity and distance of the acid varied systematically. The resulting synthetic glycosidase hydrolyzed oligosaccharides and polysaccharides in a highly controlled fashion simply in hot water. These catalysts not only broke down amylose with ...


Lithium Nickel Borides: Evolution Of [Nib] Layers Driven By Li Pressure, Volodymyr Gvozdetskyi, Yang Sun, Xin Zhao, Gourab Bhaskar, Scott L. Carnahan, Colin P. Harmer, Feng Zhang, Raquel A. Ribeiro, Paul C. Canfield, Aaron J. Rossini, Cai-Zhuang Wang, Kai-Ming Ho, Julia V. Zaikina Jan 2021

Lithium Nickel Borides: Evolution Of [Nib] Layers Driven By Li Pressure, Volodymyr Gvozdetskyi, Yang Sun, Xin Zhao, Gourab Bhaskar, Scott L. Carnahan, Colin P. Harmer, Feng Zhang, Raquel A. Ribeiro, Paul C. Canfield, Aaron J. Rossini, Cai-Zhuang Wang, Kai-Ming Ho, Julia V. Zaikina

Chemistry Publications

Here we show the effect of Li chemical pressure on the structure of layered polymorphs with LiNiB composition: RT-LiNiB (room temperature polymorph) and HT-LiNiB (high temperature polymorph), resulting in stabilization of the novel RT-Li1+xNiB (x ∼ 0.17) and HT-Li1+yNiB (y ∼ 0.06) phases. Depending on the synthesis temperature and initial Li content, precisely controlled via hydride route synthesis, [NiB] layers undergo structural deformations, allowing for extra Li atoms to be accommodated between the layers. In situ variable temperature synchrotron and time-dependent laboratory powder X-ray diffraction studies suggest Li step-wise deintercalation processes: RT-Li1+xNiB → RT-LiNiB (high temp.) → LiNi3B1.8 ...


Revealing The Surface Structure Of Cdse Nanocrystals By Dynamic Nuclear Polarization-Enhanced 77se And 113cd Solid-State Nmr Spectroscopy, Yunhua Chen, Rick W. Dorn, Michael P. Hanrahan, Lin Wei, Rafael Blome-Fernández, Alan M. Medina-Gonzalez, Marquix A. S. Adamson, Anne H. Flintgruber, Javier Vela, Aaron J. Rossini Jan 2021

Revealing The Surface Structure Of Cdse Nanocrystals By Dynamic Nuclear Polarization-Enhanced 77se And 113cd Solid-State Nmr Spectroscopy, Yunhua Chen, Rick W. Dorn, Michael P. Hanrahan, Lin Wei, Rafael Blome-Fernández, Alan M. Medina-Gonzalez, Marquix A. S. Adamson, Anne H. Flintgruber, Javier Vela, Aaron J. Rossini

Chemistry Publications

Dynamic nuclear polarization (DNP) solid-state NMR (SSNMR) spectroscopy was used to obtain detailed surface structures of zinc blende CdSe nanocrystals (NCs) with plate or spheroidal morphologies and which are capped by carboxylic acid ligands. 1D 113Cd and 77Se cross-polarization magic angle spinning (CPMAS) NMR spectra revealed distinct signals from Cd and Se atoms on the surface of the NCs, and those residing in bulk-like environments below the surface. 113Cd cross-polarization magic-angle-turning (CP-MAT) experiments identified CdSe3O, CdSe2O2, and CdSeO3 Cd coordination environments on the surface of the NCs, where the oxygen atoms are presumably from coordinated carboxylate ligands. The sensitivity gain ...


Elucidating The Role Of Hydrogen Bond Donor And Acceptor On Solvation In Deep Eutectic Solvents Formed By Ammonium/Phosphonium Salts And Carboxylic Acids, Muhammad Qamar Farooq, Gabriel A. Odugbesi, Nabeel Mujtaba Abbasi, Jared L. Anderson Dec 2020

Elucidating The Role Of Hydrogen Bond Donor And Acceptor On Solvation In Deep Eutectic Solvents Formed By Ammonium/Phosphonium Salts And Carboxylic Acids, Muhammad Qamar Farooq, Gabriel A. Odugbesi, Nabeel Mujtaba Abbasi, Jared L. Anderson

Chemistry Publications

Deep eutectic solvents (DESs) constitute a rapidly emerging class of sustainable liquids that have been widely studied and employed in chemical separations, catalysis, and electrochemistry. The unique physicochemical and solvation properties of DESs can be highly tailored by choosing the appropriate hydrogen bond acceptor (HBA) and hydrogen bond donor (HBD). Understanding the role of the HBA and HBD on the multiple solvation interactions in DESs is important to enable their judicious selection for particular applications. This work constitutes the first study to exploit chromatography to measure solute–solvent interactions of DESs using a wide array of known probe molecules. The ...


Characterizing Olefin Selectivity And Stability Of Silver Salts In Ionic Liquids Using Inverse Gas Chromatography, Philip Eor, Donghyun Ryoo, He Nan, Jared L. Anderson Dec 2020

Characterizing Olefin Selectivity And Stability Of Silver Salts In Ionic Liquids Using Inverse Gas Chromatography, Philip Eor, Donghyun Ryoo, He Nan, Jared L. Anderson

Chemistry Publications

Separation systems utilizing silver(I) ion-olefin complexation have limitations since silver(I) ions can be poisoned or reduced to metallic silver. Ionic liquids (ILs) are used as solvents for silver(I) ions to facilitate separations since their physico-chemical properties can be easily tuned. To develop separation systems with sustainable olefin selectivity, factors that affect silver(I) ion stability need to be understood. In this study, a total of 13 silver salt/IL mixtures were examined by inverse gas chromatography to identify the effects of silver salt anion and IL cation/anion combination on silver(I) ion stability. The effects of ...


Growth And Stability Of Pb Intercalated Phases Under Graphene On Sic, Shaojiang Chen, Patricia A. Thiel, E. Conrad, Michael C. Tringides Dec 2020

Growth And Stability Of Pb Intercalated Phases Under Graphene On Sic, Shaojiang Chen, Patricia A. Thiel, E. Conrad, Michael C. Tringides

Chemistry Publications

Graphene intercalation is a novel way to control graphene's band structure and generate two-dimensional quantum materials with unusual spintronic and electronic properties. Despite its importance, information about the intercalation mechanism is lacking, especially the role of low density domain boundaries between regions of graphene of different thickness. With high resolution surface diffraction we have systematically studied Pb intercalation on epi-graphene grown on SiC, with domain boundaries between buffer and single layer graphene. By examining the evolution of different diffraction spots as a function of temperature, the location of Pb and stability of the intercalated phases underneath were determined.


Unspecified Verticality Of Franck-Condon Transitions, Absorption And Emission Spectra Of Cyanine Dyes, And A Classically Inspired Approximation, Joseph D. Alia, Joseph A. Flack Nov 2020

Unspecified Verticality Of Franck-Condon Transitions, Absorption And Emission Spectra Of Cyanine Dyes, And A Classically Inspired Approximation, Joseph D. Alia, Joseph A. Flack

Chemistry Publications

The computed vertical energy, Ev,a/f, from the equilibrium geometry of the initial electronic state is frequently considered as representative of the experimental excitation/emission energy, Eabs/fl = hc/λmax. Application of the quantum mechanical version of the Franck–Condon principle does not involve precise specification of nuclear positions before, after, or during an electronic transition. Moreover, the duration of an electronic transition is not experimentally accessible in spectra with resolved vibrational structure. It is shown that computed vibronic spectra based on TDDFT methods and application of quantum mechanical FC analysis predict Eabs = hc/λ ...


Substrate–Support Interactions Mediate Hydrogenation Of Phenolic Compounds By Pd/Ceo2 Nanorods, Yeongseo An, Pranjali Naik, Igor I. Slowing, Vincenzo Venditti Nov 2020

Substrate–Support Interactions Mediate Hydrogenation Of Phenolic Compounds By Pd/Ceo2 Nanorods, Yeongseo An, Pranjali Naik, Igor I. Slowing, Vincenzo Venditti

Chemistry Publications

Ceria-supported palladium (Pd/CeO2) has spawned significant attention in recent years due to its ability to catalyze selective hydrogenation of phenolic compounds to cyclohexanones and cyclohexanols at a mild temperature and pressure. However, the mechanistic basis by which ceria enhances catalytic conversion is still unclear. Here, we use the increase in the 13C transverse relaxation rate upon the addition of nanoparticles (NPs) (13C ΔR2) to investigate the adsorption of phenolic compounds on the surface of the Pd/CeO2 catalyst by solution NMR. We show that hydroxyphenols adsorb on the support more efficiently than underivatized phenol and methoxyphenols and ...


Recent Advancements In Bipolar Electrochemical Methods Of Analysis, Kira L. Rahn, Robbyn K. Anand Nov 2020

Recent Advancements In Bipolar Electrochemical Methods Of Analysis, Kira L. Rahn, Robbyn K. Anand

Chemistry Publications

The goal of this review is to provide an overview of the advancements made in the field of bipolar electrochemistry over the past 2 years, with an emphasis on analysis. Bipolar electrodes (BPEs) are versatile, and in electroanalysis, they have been used extensively to screen electrocatalysts(1−4) and to sense biomarkers.(5−10) Their ability to modulate local electric fields lends them to the manipulation of cells and to the enrichment and separation of analytes.(11−17) Finally, by virtue of the polar and often graded profile of the interfacial potential across BPEs, they provide a platform for synthesis ...


High Layer Uniformity Of Two-Dimensional Materials Demonstrated Surprisingly From Broad Features In Surface Electron Diffraction, Shen Chen, Michael Horn Von Hoegen, Patricia A. Thiel, Adam Kaminski, Benjamin Schrunk, Thanassis Speliotis, Edward Henry Conrad, Michael C. Tringides Nov 2020

High Layer Uniformity Of Two-Dimensional Materials Demonstrated Surprisingly From Broad Features In Surface Electron Diffraction, Shen Chen, Michael Horn Von Hoegen, Patricia A. Thiel, Adam Kaminski, Benjamin Schrunk, Thanassis Speliotis, Edward Henry Conrad, Michael C. Tringides

Chemistry Publications

Paradoxically a very broad diffraction background, named the Bell-Shaped-Component (BSC), has been established as a feature of graphene growth. Although the BSC has been present in the earlier literature it has been ignored. Recent diffraction studies as a function of electron energy have shown that the BSC is not related to scattering interference. The BSC is a very strong effect, but its origin is still unclear. Here, additional experiments are carried out as a function of temperature while monitoring changes in the intensity of different spots over the range that single-layer-graphene (SLG) grows. Quantitative fitting of the profiles shows that ...


Catalytic Upcycling Of High-Density Polyethylene Via A Processive Mechanism, Akalanka Tennakoon, Xun Wu, Alexander L. Paterson, Smita Patnaik, Yuchen Pei, Anne M. Lapointe, Salai C. Ammal, Ryan A. Hackler, Andreas Heyden, Igor I. Slowing, Geoffrey W. Coates, Massimiliano Delferro, Baron Peters, Wenyu Huang, Aaron D. Sadow, Frédéric A. Perras Oct 2020

Catalytic Upcycling Of High-Density Polyethylene Via A Processive Mechanism, Akalanka Tennakoon, Xun Wu, Alexander L. Paterson, Smita Patnaik, Yuchen Pei, Anne M. Lapointe, Salai C. Ammal, Ryan A. Hackler, Andreas Heyden, Igor I. Slowing, Geoffrey W. Coates, Massimiliano Delferro, Baron Peters, Wenyu Huang, Aaron D. Sadow, Frédéric A. Perras

Chemistry Publications

The overconsumption of single-use plastics is creating a global waste catastrophe, with widespread environmental, economic and health-related consequences. Here we show that the benefits of processive enzyme-catalysed conversions of biomacromolecules can be leveraged to affect the selective hydrogenolysis of high-density polyethylene into a narrow distribution of diesel and lubricant-range alkanes using an ordered, mesoporous shell/active site/core catalyst architecture that incorporates catalytic platinum sites at the base of the mesopores. Solid-state nuclear magnetic resonance revealed that long hydrocarbon macromolecules readily move within the pores of this catalyst, with a subsequent escape being inhibited by polymer–surface interactions, a behaviour ...


T1-Noise Eliminated Dipolar Heteronuclear Multiple-Quantum Coherence Solid-State Nmr Spectroscopy, Amrit Venkatesh, Xuechen Luan, Frédéric A. Perras, Ivan Hung, Wenyu Huang, Aaron Rossini Sep 2020

T1-Noise Eliminated Dipolar Heteronuclear Multiple-Quantum Coherence Solid-State Nmr Spectroscopy, Amrit Venkatesh, Xuechen Luan, Frédéric A. Perras, Ivan Hung, Wenyu Huang, Aaron Rossini

Chemistry Publications

Heteronuclear correlation (HETCOR) spectroscopy is one of the key tools in the arsenal of the solid-state NMR spectroscopist to probe spatial proximity between two different nuclei and enhance spectral resolution. Dipolar heteronuclear multiple-quantum coherence (D-HMQC) is a powerful technique that can be potentially utilized to obtain 1H detected 2D HETCOR solid-state NMR spectra of any NMR active nucleus. A long-standing problem in 1H detected D-HMQC solid-state NMR experiments is the presence of t1-noise which reduces sensitivity and impedes spectral interpretation. In this contribution, we describe novel pulse sequences, termed t1-noise eliminated (TONE) D-HMQC, that ...


Three-Dimensional Profiling Of Oled By Laser Desorption Ionization-Mass Spectrometry Imaging, Andrew E. Paulson, Trevor T. Forsman, Young Jin Lee Sep 2020

Three-Dimensional Profiling Of Oled By Laser Desorption Ionization-Mass Spectrometry Imaging, Andrew E. Paulson, Trevor T. Forsman, Young Jin Lee

Chemistry Publications

Organic light emitting devices (OLEDs), especially in a screen display format, present unique and interesting substrates for Laser Desorption/Ionization - Mass Spectrometry Imaging (LDI-MSI) analysis. These devices contain many compounds that inherently absorb light energy and do not require an additional matrix to induce desorption and ionization. OLED screens have lateral features with dimensions that are tens of microns in magnitude and depth features that are tens to hundreds of nanometers thick. Monitoring the chemical composition of these features is essential, as contamination and degradation can impact device lifetime. This work demonstrates the capability of LDI-MSI to obtain lateral and ...


Weak Binding To The A2re Rna Rigidifies Hnrnpa2 Rrms And Reduces Liquid–Liquid Phase Separation And Aggregation, Veronica H. Ryan, Scott Watters, Joshua Amaya, Balabhadra Khatiwada, Vincenzo Venditti, Mandar T. Naik, Nicolas L. Fawzi Sep 2020

Weak Binding To The A2re Rna Rigidifies Hnrnpa2 Rrms And Reduces Liquid–Liquid Phase Separation And Aggregation, Veronica H. Ryan, Scott Watters, Joshua Amaya, Balabhadra Khatiwada, Vincenzo Venditti, Mandar T. Naik, Nicolas L. Fawzi

Chemistry Publications

hnRNPA2 is a major component of mRNA transport granules in oligodendrocytes and neurons. However, the structural details of how hnRNPA2 binds the A2 recognition element (A2RE) and if this sequence stimulates granule formation by enhancing phase separation of hnRNPA2 has not yet been studied. Using solution NMR and biophysical studies, we find that each of the two individual RRMs retain the domain structure observed in complex with RNA but are not rigidly confined (i.e. they move independently) in solution in the absence of RNA. hnRNPA2 RRMs bind the minimal rA2RE11 weakly but at least, and most likely, two hnRNPA2 ...


Synthesis Of Interface-Driven Tunable Bandgap Metal Oxides, Boyce S. Chang, Andrew Martin, Brijith Thomas, Ang Li, Rick W. Dorn, Jinlong Gong, Aaron J. Rossini, Martin M. Thuo Aug 2020

Synthesis Of Interface-Driven Tunable Bandgap Metal Oxides, Boyce S. Chang, Andrew Martin, Brijith Thomas, Ang Li, Rick W. Dorn, Jinlong Gong, Aaron J. Rossini, Martin M. Thuo

Chemistry Publications

Mixed bandgap and bandgap tunability in semiconductors is critical in expanding their use. Composition alterations through single-crystal epitaxial growth and the formation of multilayer tandem structures are often employed to achieve mixed bandgaps, albeit with limited tunability. Herein, self-assembled one-dimensional coordination polymers provide facile synthons and templates for graphitic C-doped mesoporous oxides, gC-β-Ga2O3 or gC-In2O3 via controlled oxidative ligand ablation. These materials have mixed bandgaps and colors, depending on amount of gC present. The carbon/oxide interface leads to induced gap states, hence, a stoichiometrically tunable band structure. Structurally, a multiscale porous network percolating throughout the material is realized. The ...


Efficient Far-Red/Near-Ir Absorbing Bodipy Photocages By Blocking Unproductive Conical Intersections, Pradeep Shrestha, Komadhie C. Dissanayake, Elizabeth J. Gehrmann, Chamari S. Wijesooriya, Atreyee Mukhopadhyay, Emily A. Smith, Arthur Winter Aug 2020

Efficient Far-Red/Near-Ir Absorbing Bodipy Photocages By Blocking Unproductive Conical Intersections, Pradeep Shrestha, Komadhie C. Dissanayake, Elizabeth J. Gehrmann, Chamari S. Wijesooriya, Atreyee Mukhopadhyay, Emily A. Smith, Arthur Winter

Chemistry Publications

Photocages are light-sensitive chemical protecting groups that give investigators control over activation of biomolecules using targeted light irradiation. A compelling application of far-red/near-IR absorbing photocages is their potential for deep tissue activation of biomolecules and phototherapeutics. Towards this goal, we recently reported BODIPY photocages that absorb near-IR light. However, these photocages have reduced photorelease efficiencies compared to shorter-wavelength absorbing photocages, which has hindered their application. Because photochemistry is a zero-sum competition of rates, improving the quantum yield of a photoreaction can be achieved either by making the desired photoreaction more efficient or by hobbling competitive decay channels. This latter ...


Reshaping Of Truncated Pd Nanocubes: Energetic And Kinetic Analysis Integrating Transmission Electron Microscopy With Atomistic-Level And Coarse-Grained Modeling, King C. Lai, Minda Chen, Benjamin Williams, Yong Han, Chia-Kuang Tsung, Wenyu Huang, James W. Evans Jul 2020

Reshaping Of Truncated Pd Nanocubes: Energetic And Kinetic Analysis Integrating Transmission Electron Microscopy With Atomistic-Level And Coarse-Grained Modeling, King C. Lai, Minda Chen, Benjamin Williams, Yong Han, Chia-Kuang Tsung, Wenyu Huang, James W. Evans

Chemistry Publications

Stability against reshaping of metallic fcc nanocrystals synthesized with tailored far-from-equilibrium shapes is key to maintaining optimal properties for applications such as catalysis. Yet Arrhenius analysis of experimental reshaping kinetics, and appropriate theory and simulation, is lacking. Thus, we use TEM to monitor the reshaping of Pd nanocubes of ∼25 nm side length between 410 °C (over ∼4.5 h) and 440 °C (over ∼0.25 h), extracting a high effective energy barrier of Eeff ≈ 4.6 eV. We also provide an analytic determination of the energy variation along the optimal pathway for reshaping that involves transfer of atoms across ...


Solvent-Responsive Radical Dimers, Joshua P. Peterson, Arthur H. Winter Jul 2020

Solvent-Responsive Radical Dimers, Joshua P. Peterson, Arthur H. Winter

Chemistry Publications

An air- and thermally stable aryl dicyanomethyl radical is reported that switches between two dimeric forms—a σ dimer and a π dimer—by changing the solvent. The two dimer forms exhibit unique optical properties leading to solvatochromic behavior. The solvent-responsive behavior of these radicals can be explained by the higher polarizability of the pimer than the σ dimer that leads to pimer stabilization in polar solvents.