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Full-Text Articles in Physical Sciences and Mathematics

Nanoparticle Microarray For High-Throughput Microbiome Metabolomics Using Matrix-Assisted Laser Desorption Ionization Mass Spectrometry, Rebecca L. Hansen, Maria Emilia Duenas, Torey Looft, Young Jin Lee Oct 2018

Nanoparticle Microarray For High-Throughput Microbiome Metabolomics Using Matrix-Assisted Laser Desorption Ionization Mass Spectrometry, Rebecca L. Hansen, Maria Emilia Duenas, Torey Looft, Young Jin Lee

Chemistry Publications

A high-throughput matrix-assisted laser desorption/ionization mass spectrometry (MALDI)-MS-based metabolomics platform was developed using a pre-fabricated microarray of nanoparticles and organic matrices. Selected organic matrices, inorganic nanoparticle (NP) suspensions, and sputter coated metal NPs, as well as various additives, were tested for metabolomics analysis of the turkey gut microbiome. Four NPs and one organic matrix were selected as the optimal matrix set: α-cyano-4-hydroycinnamic acid, Fe3O4 and Au NPs in positive ion mode with 10 mM sodium acetate, and Cu and Ag NPs in negative ion mode with no additive. Using this set of five matrices, over two thousand unique ...


Bdpa-Nitroxide Biradicals Tailored For Efficient Dynamic Nuclear Polarization Enhanced Solid-State Nmr At Magnetic Fields Up To 21.1 T, Dorothea Wisser, Ganesan Karthikeyan, Alicia Lund, Gilles Casano, Hakim Karoui, Maxim Yulikov, Georges Menzildjian, Arthur C. Pinon, Armin Purea, Frank Engelke, Sachin R. Chaudhari, Dominik Kubicki, Aaron Rossini, Ilia B. Moroz, David Gajan, Christophe Copéret, Gunnar Jeschke, Moreno Lelli, Lyndon Emsley, Anne Lesage, Olivier Ouari Sep 2018

Bdpa-Nitroxide Biradicals Tailored For Efficient Dynamic Nuclear Polarization Enhanced Solid-State Nmr At Magnetic Fields Up To 21.1 T, Dorothea Wisser, Ganesan Karthikeyan, Alicia Lund, Gilles Casano, Hakim Karoui, Maxim Yulikov, Georges Menzildjian, Arthur C. Pinon, Armin Purea, Frank Engelke, Sachin R. Chaudhari, Dominik Kubicki, Aaron Rossini, Ilia B. Moroz, David Gajan, Christophe Copéret, Gunnar Jeschke, Moreno Lelli, Lyndon Emsley, Anne Lesage, Olivier Ouari

Chemistry Publications

Dynamic Nuclear Polarization (DNP) solid-state NMR has developed into an invaluable tool for the investigation of a wide range of materials. However, the sensitivity gain achieved with many polarizing agents suffers from an unfavorable field and Magic Angle Spinning (MAS) frequency dependence. We present a series of new hybrid biradicals, soluble in organic solvents, that consist of an isotropic narrow EPR line radical, BDPA, tethered to a broad line nitroxide. By tuning the distance between the two electrons and the substituents at the nitroxide moiety, correlations between the electron-electron interactions and the electronic spin relaxation times on one hand, and ...


Sensitivity-Enhanced 207pb Solid-State Nmr Spectroscopy For The Rapid, Non-Destructive Characterization Of Organolead Halide Perovskites, Michael P. Hanrahan, Long Men, Bryan A. Rosales, Javier Vela, Aaron J. Rossini Sep 2018

Sensitivity-Enhanced 207pb Solid-State Nmr Spectroscopy For The Rapid, Non-Destructive Characterization Of Organolead Halide Perovskites, Michael P. Hanrahan, Long Men, Bryan A. Rosales, Javier Vela, Aaron J. Rossini

Chemistry Publications

Organolead halide and mixed halide perovskites (CH3NH3PbX3, CH3NH3PbX3–nYn, X and Y = Cl–, Br– or I–), are promising materials for photovoltaics and optoelectronic devices. 207Pb solid-state NMR spectroscopy has previously been applied to characterize phase segregation and halide ion speciation in mixed halide perovskites. However, NMR spectroscopy is an insensitive technique that often requires large sample volumes and long signal averaging periods. This is especially true for mixed halide perovskites, which give rise to extremely broad 207Pb solid-state NMR spectra. Here, we quantitatively compare the sensitivity of the various solid-state NMR techniques on pure and mixed halide organolead perovskites and ...


Materials Characterization By Dynamic Nuclear Polarization Enhanced Solid-State Nmr Spectroscopy, Aaron Rossini Aug 2018

Materials Characterization By Dynamic Nuclear Polarization Enhanced Solid-State Nmr Spectroscopy, Aaron Rossini

Chemistry Publications

High-resolution solid-state NMR spectroscopy is a powerful tool for the study of organic and inorganic materials because it can directly probe the symmetry and structure at nuclear sites, the connectivity/bonding of atoms and precisely measure inter-atomic distances. However, NMR spectroscopy is hampered by intrinsically poor sensitivity, consequently, the application of NMR spectroscopy to many solid materials is often infeasible. High-field dynamic nuclear polarization (DNP) has emerged as a technique to routinely enhance the sensitivity of solid-state NMR experiments by one to three orders of magnitude. This perspective gives a general overview of how DNP enables advanced solid-state NMR experiments ...


Expanding The I-Ii-V Phase Space: Soft Synthesis Of Polytypic Ternary And Binary Zinc Antimonides, Miles A. White, Katelyn J. Baumler, Yunhua Chen, Amrit Venkatesh, Alan M. Medina-Gonzalez, Aaron Rossini, Julia Zaikina, Emory Chan, Javier Vela Aug 2018

Expanding The I-Ii-V Phase Space: Soft Synthesis Of Polytypic Ternary And Binary Zinc Antimonides, Miles A. White, Katelyn J. Baumler, Yunhua Chen, Amrit Venkatesh, Alan M. Medina-Gonzalez, Aaron Rossini, Julia Zaikina, Emory Chan, Javier Vela

Chemistry Publications

Soft chemistry methods offer the possibility of synthesizing metastable and kinetic products that are unobtainable through thermodynamically-controlled, high-temperature reactions. A recent solution-phase exploration of Li-Zn-Sb phase space revealed a previously unknown cubic half-Heusler MgAgAs-type LiZnSb polytype. Interestingly, this new cubic phase was calculated to be the most thermodynamically stable, despite prior literature reporting only two other ternary phases (the hexagonal half-Heusler LiGaGe-type LiZnSb, and the full-Heusler Li2ZnSb). This surprising discovery, coupled with the intriguing optoelectronic and transport properties of many antimony containing Zintl phases, required a thorough exploration of syn-thetic parameters. Here, we systematically study the effects that different precursor ...


Open Resonance Assisted Hydrogen Bonds And Competing Quasiaromaticity, Yen H. Nguyen, Bryan J. Lampkin, Amrit Venkatesh, Arkady Ellern, Aaron J. Rossini, Brett Vanveller Jul 2018

Open Resonance Assisted Hydrogen Bonds And Competing Quasiaromaticity, Yen H. Nguyen, Bryan J. Lampkin, Amrit Venkatesh, Arkady Ellern, Aaron J. Rossini, Brett Vanveller

Chemistry Publications

The delocalization of electron density upon tautomerization of a proton across a conjugated bridge can alter the strength of hydrogen bonds. This effect has been dubbed resonance-assisted hydrogen bonding (RAHB) and plays a major role in the energetics of the tautomeric equilibrium. The goal of this work was to investigate the role that π-delocalization plays in the stability of RAHBs by engaging other isomerization processes. Similarly, acid-base chemistry has received little experimental attention in studies of RAHB and we address the role that acid-base effects play in the tautomeric equilibrium. We find that π-delocalization and the disruption of adjacent aromatic ...


Characterizing Virus-Induced Gene Silencing At The Cellular Level With In Situ Multimodal Imaging, Sadie J. Burkhow, Nicole M. Stephens, Yu Mei, Maria Emilia Duenas, Daniel J. Freppon, Geng Ding, Shea C. Smith, Young-Jin Lee, Basil J. Nikolau, Steven A. Whitham, Emily A. Smith May 2018

Characterizing Virus-Induced Gene Silencing At The Cellular Level With In Situ Multimodal Imaging, Sadie J. Burkhow, Nicole M. Stephens, Yu Mei, Maria Emilia Duenas, Daniel J. Freppon, Geng Ding, Shea C. Smith, Young-Jin Lee, Basil J. Nikolau, Steven A. Whitham, Emily A. Smith

Chemistry Publications

Background: Reverse genetic strategies, such as virus-induced gene silencing, are powerful techniques to study gene function. Currently, there are few tools to study the spatial dependence of the consequences of gene silencing at the cellular level.

Results: We report the use of multimodal Raman and mass spectrometry imaging to study the cellular-level biochemical changes that occur from silencing the phytoene desaturase (pds) gene using a Foxtail mosaic virus (FoMV) vector in maize leaves. The multimodal imaging method allows the localized carotenoid distribution to be measured and reveals differences lost in the spatial average when analyzing a carotenoid extraction of the ...


Group 13 Complexes Of Chelating N2o2n‒ Ligands As Hybrid Molecular Materials, Ryan R. Maar, Joe B. Gilroy Apr 2018

Group 13 Complexes Of Chelating N2o2n‒ Ligands As Hybrid Molecular Materials, Ryan R. Maar, Joe B. Gilroy

Chemistry Publications

Recent synthetic advances have afforded opportunities for the creation of a wide range of potentially tetradentate N2O2n‒ ligands. When combined with group 13 elements, robust functional molecular materials can be realized. This concept article describes advances surrounding group 13 complexes of selected families of N2O2n‒ ligands, including examples with unique chirality, sensing/detection capabilities, utility in organic electronics, and redox properties. It also highlights the bridge between fundamental main group chemistry and useful application that is being established within this research field.


Revealing Individual Lifestyles Through Mass Spectrometry Imaging Of Chemical Compounds In Fingerprints, Paige Hinners, Kelly C. O’Neill, Young Jin Lee Mar 2018

Revealing Individual Lifestyles Through Mass Spectrometry Imaging Of Chemical Compounds In Fingerprints, Paige Hinners, Kelly C. O’Neill, Young Jin Lee

Chemistry Publications

Fingerprints, specifically the ridge details within the print, have long been used in forensic investigations for individual identification. Beyond the ridge detail, fingerprints contain useful chemical information. The study of fingerprint chemical information has become of interest, especially with mass spectrometry imaging technologies. Mass spectrometry imaging visualizes the spatial relationship of each compound detected, allowing ridge detail and chemical information in a single analysis. In this work, a range of exogenous fingerprint compounds that may reveal a personal lifestyle were studied using matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI). Studied chemical compounds include various brands of bug sprays and ...


Indole Anion Cycloadditions With Methyl Coumalate, George A. Kraus, Huangchao Yu Feb 2018

Indole Anion Cycloadditions With Methyl Coumalate, George A. Kraus, Huangchao Yu

Chemistry Publications

The reaction of the anion of indoles with methyl coumalate followed by selective opening of the lactone led to the preparation of tricyclic intermediates for indole alkaloid synthesis.


The Oligomerization State Of Bacterial Enzyme I (Ei) Determines Ei's Allosteric Stimulation Or Competitive Inhibition By Α-Ketoglutarate, Trang T. Nguyen, Rodolfo Ghirlando, Vincenzo Venditti Feb 2018

The Oligomerization State Of Bacterial Enzyme I (Ei) Determines Ei's Allosteric Stimulation Or Competitive Inhibition By Α-Ketoglutarate, Trang T. Nguyen, Rodolfo Ghirlando, Vincenzo Venditti

Chemistry Publications

The bacterial phosphotransferase system (PTS) is a signal transduction pathway that couples phosphoryl transfer to active sugar transport across the cell membrane. The PTS is initiated by phosphorylation of enzyme I (EI) by phosphoenolpyruvate (PEP). The EI phosphorylation state determines the phosphorylation states of all other PTS components and is thought to play a central role in the regulation of several metabolic pathways and to control the biology of bacterial cells at multiple levels, for example, affecting virulence and biofilm formation. Given the pivotal role of EI in bacterial metabolism, an improved understanding of the mechanisms controlling its activity could ...


The Acs Exams Institute Undergraduate Chemistry Anchoring Concepts Content Map Iv: Physical Chemistry, Thomas A. Holme, Jessica J. Reed, Jeffrey R. Raker, Kristen L. Murphy Feb 2018

The Acs Exams Institute Undergraduate Chemistry Anchoring Concepts Content Map Iv: Physical Chemistry, Thomas A. Holme, Jessica J. Reed, Jeffrey R. Raker, Kristen L. Murphy

Chemistry Publications

The ACS Examinations Institute has been developing Anchoring Concepts Content Maps to provide an organizational template for the four-year undergraduate chemistry curriculum. In order to accomplish this goal, specific subdisciplinary versions of the map share the two top levels but distinguish themselves at the bottom two levels which contain finer-grained content details. This structure has been refined and vetted over a number of meetings and workshops. This paper presents the four levels of the content map for physical chemistry.


The Acs Exams Institute Undergraduate Chemistry Anchoring Concepts Content Map Iii: Inorganic Chemistry, Keith A. Marek, Jeffery R. Raker, Thomas A. Holme, Kristen L. Murphy Feb 2018

The Acs Exams Institute Undergraduate Chemistry Anchoring Concepts Content Map Iii: Inorganic Chemistry, Keith A. Marek, Jeffery R. Raker, Thomas A. Holme, Kristen L. Murphy

Chemistry Publications

For the past eight years, the ACS Examinations Institute has been developing Anchoring Concepts Content Maps for the different subdisciplines taught throughout the undergraduate curriculum. The structure of the map consists of two top levels that are shared throughout the entire curriculum and two subdiscipline specific levels that contain finer-grained content details. This paper presents the four levels of the content map for inorganic chemistry.


Automated Nmr Resonance Assignments And Structure Determination Using A Minimal Set Of 4d Spectra, Thomas Evangelidis, Santrupti Nerli, Jiří Nováček, Andrew E. Brereton, P. Andrew Karplus, Rochelle R. Dotas, Vincenzo Venditti, Nikolaos G. Sgourakis, Konstantinos Tripsianes Jan 2018

Automated Nmr Resonance Assignments And Structure Determination Using A Minimal Set Of 4d Spectra, Thomas Evangelidis, Santrupti Nerli, Jiří Nováček, Andrew E. Brereton, P. Andrew Karplus, Rochelle R. Dotas, Vincenzo Venditti, Nikolaos G. Sgourakis, Konstantinos Tripsianes

Chemistry Publications

Automated methods for NMR structure determination of proteins are continuously becoming more robust. However, current methods addressing larger, more complex targets rely on analyzing 6–10 complementary spectra, suggesting the need for alternative approaches. Here, we describe 4D-CHAINS/autoNOE-Rosetta, a complete pipeline for NOE-driven structure determination of medium- to larger-sized proteins. The 4D-CHAINS algorithm analyzes two 4D spectra recorded using a single, fully protonated protein sample in an iterative ansatz where common NOEs between different spin systems supplement conventional through-bond connectivities to establish assignments of sidechain and backbone resonances at high levels of completeness and with a minimum error rate ...


Synthesis Of Isophthalates From Methyl Coumalate, George A. Kraus, Shuai Wang Dec 2017

Synthesis Of Isophthalates From Methyl Coumalate, George A. Kraus, Shuai Wang

Chemistry Publications

Methyl coumalate reacts with enol ethers to form stable adducts which can be converted into isophthalates in good to excellent yields. Alkyl vinyl ethers afford higher yields of isophthalates than enol silyl ethers. The adduct of the enol silyl ether of acetophenone with methyl coumalate reacted with PTSA to produce a styryl coumalate.


1,6-Diphenyl-1,3,5-Hexatriene (Dph) As A Novel Matrix For Maldi Ms Imaging Of Fatty Acids, Phospholipids, And Sulfatides In Brain Tissues., Hanadi Ibrahim, Kristina Jurcic, Jasmine S-H Wang, Shawn N Whitehead, Ken K-C Yeung Dec 2017

1,6-Diphenyl-1,3,5-Hexatriene (Dph) As A Novel Matrix For Maldi Ms Imaging Of Fatty Acids, Phospholipids, And Sulfatides In Brain Tissues., Hanadi Ibrahim, Kristina Jurcic, Jasmine S-H Wang, Shawn N Whitehead, Ken K-C Yeung

Chemistry Publications

1,6-Diphenyl-1,3,5-hexatriene (DPH) is a commonly used fluorescence probe for studying cell membrane-lipids due to its affinity toward the acyl chains in the phospholipid bilayers. In this work, we investigated its use in matrix-assisted laser desorption/ionization (MALDI) as a new matrix for mass spectrometry imaging (MSI) of mouse and rat brain tissue. DPH exhibits very minimal matrix-induced background signals for the analysis of small molecules (below m/z of 1000). In the negative ion mode, DPH permits the highly sensitive detection of small fatty acids (m/z 200-350) as well as a variety of large lipids up ...


Identification And Characterization Of Small Molecule Inhibitors Of Porcine Reproductive And Respiratory Syndrome Virus, Alyssa B. Evans, Pengfei Dong, Hyelee Loyd, Jianqiang Zhang, George A. Kraus, Susan Carpenter Oct 2017

Identification And Characterization Of Small Molecule Inhibitors Of Porcine Reproductive And Respiratory Syndrome Virus, Alyssa B. Evans, Pengfei Dong, Hyelee Loyd, Jianqiang Zhang, George A. Kraus, Susan Carpenter

Chemistry Publications

Porcine reproductive and respiratory syndrome virus (PRRSV) is the etiological agent of PRRS, an economically significant disease of swine worldwide. PRRSV is poorly controlled by the currently available vaccines, and alternative control strategies are needed to help prevent the continual circulation of the virus. Previously, we developed a synthetic route for the natural compound atractylodinol and demonstrated anti-PRRSV activity in vitro. However, the synthetic route was inefficient and the yield was poor. To identify PRRSV inhibitors that could be synthesized easily and cost-effectively, we synthesized a series of atractylodinol analogs and characterized their anti-PRRSV activity in vitro. A furan-substituted bis-enyne ...


Aluminum Complexes Of N2o23‒ Formazanate Ligands Supported By Phosphine Oxide Donors, Ryan Maar, Amir Rabiee Kenaree, Ruizhong Zhang, Yichen Tao, Benjamin D. Katzman, Viktor N. Staroverov, Zhifeng Ding, Joe Gilroy Sep 2017

Aluminum Complexes Of N2o23‒ Formazanate Ligands Supported By Phosphine Oxide Donors, Ryan Maar, Amir Rabiee Kenaree, Ruizhong Zhang, Yichen Tao, Benjamin D. Katzman, Viktor N. Staroverov, Zhifeng Ding, Joe Gilroy

Chemistry Publications

The synthesis and characterization of a new family of phosphine-oxide-supported aluminum formazanate complexes (7a, 7b, 8a, 9a) are reported. X-ray diffraction studies revealed that the aluminum atoms in the complexes adopt an octahedral geometry in the solid state. The equatorial positions are occupied by an N2O23‒ formazanate ligand, and the axial positions are occupied by L-type phosphine oxide donors. UV-vis absorption spectroscopy revealed that the complexes were strongly absorbing (ε ~ 30,000 M‒1 cm‒1) between 500 and 700 nm. The absorption maxima in this region were simulated using time-dependent density-functional theory. With the exception ...


Boron Difluoride Adducts Of A Flexidentate Pyridine-Substituted Formazanate Ligand: Property Modulation Via Protonation And Coordination Chemistry, Stephanie M. Barbon, Jasmine V. Buddingh, Ryan R. Maar, Joe Gilroy Sep 2017

Boron Difluoride Adducts Of A Flexidentate Pyridine-Substituted Formazanate Ligand: Property Modulation Via Protonation And Coordination Chemistry, Stephanie M. Barbon, Jasmine V. Buddingh, Ryan R. Maar, Joe Gilroy

Chemistry Publications

The synthesis and characterization of a flexidentate pyridine-substituted formazanate ligand and its boron difluoride adducts, formed via two different coordination modes of the title ligand, are described. The first adduct adopted a structure that was typical of other boron difluoride adducts of triarylformazanate ligands and contained a free pyridine subsituent, while the second was formed via chelation of nitrogen atoms from the formazanate backbone and the pyridine substituent. Stepwise protonation of the pydridine-functionalized adduct, which is essentially non-emissive, resulted in a significant increase in the fluorescence quantum yield up to a maximum of 18%, prompting study of this adduct as ...


(Co)Polymers Containing Boron Difluoride 3-Cyanoformazanate Complexes: Emission Enhancement Via Random Copolymerization, Joe Gilroy, Samantha Novoa Aug 2017

(Co)Polymers Containing Boron Difluoride 3-Cyanoformazanate Complexes: Emission Enhancement Via Random Copolymerization, Joe Gilroy, Samantha Novoa

Chemistry Publications

Ring-opening metathesis polymerization was used to produce polymers bearing an asymmetrically substituted boron difluoride 3-cyanoformazanate complex. The polymers were found to retain many of the unique characteristics of molecular boron difluoride complexes of 3-cyanoformazanates, including intense light absorption at ca. 560 nm and reversible electrochemical reductions implicating the radical anion and dianion forms of the formazanate complexes in the repeating unit of the polymer backbone. The polymers were also found to be emissive, with emission maxima centred at ca. 665 nm. The monomer employed in this study had a fluorescence quantum yield of 30%, while homopolymers were weakly emissive and ...


Beyond “Inert” Ideas To Teaching General Chemistry From Rich Contexts: Visualizing The Chemistry Of Climate Change (Vc3), Peter G. Mahaffy, Thomas A. Holme, Leah Martin-Visscher, Brian E. Martin, Ashley Versprille, Mary Kirchhoff, Lallie Mckenzie, Marcy Towns Aug 2017

Beyond “Inert” Ideas To Teaching General Chemistry From Rich Contexts: Visualizing The Chemistry Of Climate Change (Vc3), Peter G. Mahaffy, Thomas A. Holme, Leah Martin-Visscher, Brian E. Martin, Ashley Versprille, Mary Kirchhoff, Lallie Mckenzie, Marcy Towns

Chemistry Publications

As one approach to moving beyond transmitting “inert” ideas to chemistry students, we use the term “teaching from rich contexts” to describe implementations of case studies or context-based learning based on systems thinking that provide deep and rich opportunities for learning crosscutting concepts through contexts. This approach nurtures the use of higher-order cognitive skills to connect concepts and apply the knowledge gained to new contexts. We describe the approach used to design a set of resources that model how rich contexts can be used to facilitate learning of general chemistry topics. The Visualizing the Chemistry of Climate Change (VC3) initiative ...


Mechanistic Insight Into Nanoparticle Surface Adsorption By Solution Nmr Spectroscopy In An Aqueous Gel, Timothy K. Egner, Pranjali Naik, Nicholas C. Nelson, Igor I. Slowing, Vincenzo Venditti Aug 2017

Mechanistic Insight Into Nanoparticle Surface Adsorption By Solution Nmr Spectroscopy In An Aqueous Gel, Timothy K. Egner, Pranjali Naik, Nicholas C. Nelson, Igor I. Slowing, Vincenzo Venditti

Chemistry Publications

Engineering nanoparticle (NP) functions at the molecular level requires a detailed understanding of the dynamic processes occurring at the NP surface. Herein we show that a combination of dark‐state exchange saturation transfer (DEST) and relaxation dispersion (RD) NMR experiments on gel‐stabilized NP samples enables the accurate determination of the kinetics and thermodynamics of adsorption. We used the former approach to describe the interaction of cholic acid (CA) and phenol (PhOH) with ceria NPs with a diameter of approximately 200 nm. Whereas CA formed weak interactions with the NPs, PhOH was tightly bound to the NP surface. Interestingly, we ...


Polar Intermetallics Pr5co2ge3 And Pr7co2ge4 With Planar Hydrocarbon‐Like Metal Clusters, Qisheng Lin, Kaiser Aguirre, Scott M. Saunders, Timothy A. Hackett, Yong Liu, Valentin Taufour, Durga Paudyal, Sergey L. Bud’Ko, Paul C. Canfield, Gordon J. Miller Aug 2017

Polar Intermetallics Pr5co2ge3 And Pr7co2ge4 With Planar Hydrocarbon‐Like Metal Clusters, Qisheng Lin, Kaiser Aguirre, Scott M. Saunders, Timothy A. Hackett, Yong Liu, Valentin Taufour, Durga Paudyal, Sergey L. Bud’Ko, Paul C. Canfield, Gordon J. Miller

Chemistry Publications

Planar hydrocarbon‐like metal clusters may foster new insights linking organic molecules with conjugated π–π bonding interactions and inorganic structures in terms of their bonding characteristics. However, such clusters are uncommon in polar intermetallics. Herein, we report two polar intermetallic phases, Pr5Co2Ge3 and Pr7Co2Ge4, both of which feature such planar metal clusters, namely, ethylene‐like [Co2Ge4] clusters plus the concatenated forms and polyacene‐like [Co2Ge2]n ribbons in Pr5Co2Ge3, and 1,2,4,5‐tetramethylbenzene‐like [Co4Ge6] cluster in Pr7Co2Ge4. Just as in the related planar organic structures, these metal–metalloid species are dominated by covalent bonding interactions. Both ...


Spatial Mapping And Profiling Of Metabolite Distributions During Germination, Adam D. Feenstra, Liza E. Alexander, Zhihong Song, Andrew R. Korte, Marna D. Yandeau-Nelson, Basil J. Nikolau, Young-Jin Lee Aug 2017

Spatial Mapping And Profiling Of Metabolite Distributions During Germination, Adam D. Feenstra, Liza E. Alexander, Zhihong Song, Andrew R. Korte, Marna D. Yandeau-Nelson, Basil J. Nikolau, Young-Jin Lee

Chemistry Publications

Germination is a highly complex process by which seeds begin to develop and establish themselves as viable organisms. In this paper, we utilize a combination of GC-MS, LC-fluorescence, and mass spectrometry imaging (MSI) approaches to profile and visualize the metabolic distributions of germinating seeds from two different inbreds of maize seeds, B73 and Mo17. GC and LC analyses demonstrate that the two inbreds are highly differentiated in their metabolite profiles throughout the course of germination, especially with regard to amino acids, sugar alcohols, and small organic acids. Crude dissection of the seed followed by GC-MS analysis of polar metabolites also ...


Crystal Structure, Homogeneity Range And Electronic Structure Of Rhombohedral Γ-Mn5al8, Srinivasa Thimmaiah, Zachary Tener, Tej N. Lamichhane, Paul C. Canfield, Gordon J. Miller Jul 2017

Crystal Structure, Homogeneity Range And Electronic Structure Of Rhombohedral Γ-Mn5al8, Srinivasa Thimmaiah, Zachary Tener, Tej N. Lamichhane, Paul C. Canfield, Gordon J. Miller

Chemistry Publications

The γ-region of the Mn–Al phase diagram between 45 and 70 at.% Al was re-investigated by a combination of powder and single crystal X-ray diffraction as well as EDS analysis to establish the distribution of Mn and Al atoms. Single crystals of γ-Mn5–x Al8+x were grown using Sn-flux at 650 °C. The crystal structure, atomic coordinates and site occupancy parameters of γ-Mn5−x Al8+x phases were refined from single crystal X-ray data. The γ-Mn5-x Al8+x phase adopts the rhombohedral Cr5Al8-type structure rather than a cubic γ-brass structure. The refined compositions from two crystals extracted ...


Germanium–Tin/Cadmium Sulfide Core/Shell Nanocrystals With Enhanced Near-Infrared Photoluminescence, Brett W. Boote, Long Men, Himashi P. Andaraarachchi, Ujjal Bhattacharjee, Jacob W. Petrich, Javier Vela, Emily A. Smith Jul 2017

Germanium–Tin/Cadmium Sulfide Core/Shell Nanocrystals With Enhanced Near-Infrared Photoluminescence, Brett W. Boote, Long Men, Himashi P. Andaraarachchi, Ujjal Bhattacharjee, Jacob W. Petrich, Javier Vela, Emily A. Smith

Chemistry Publications

Ge1–xSnx alloy nanocrystals and Ge1–xSnx/CdS core/shell nanocrystals were prepared via solution phase synthesis, and their size, composition, and optical properties were characterized. The diameter of the nanocrystal samples ranged from 6 to 13 nm. The crystal structure of the Ge1–xSnx materials was consistent with a cubic diamond phase, while the CdS shell was consistent with the zinc blende polytype. Inclusion of Sn alone does not result in enhanced photoluminescence intensity; however, adding an epitaxial CdS shell onto the Ge1–xSnxnanocrystals does enhance the photoluminescence up to ...


The Solvent- Solid Interface Of Acid Catalysts Studied By High Resolution Mas Nmr, Robert L. Johnson, Michael P. Hanrahan, Max Mellmer, James A. Dumesic, Aaron J. Rossini, Brent H. Shanks Jul 2017

The Solvent- Solid Interface Of Acid Catalysts Studied By High Resolution Mas Nmr, Robert L. Johnson, Michael P. Hanrahan, Max Mellmer, James A. Dumesic, Aaron J. Rossini, Brent H. Shanks

Chemistry Publications

High-resolution magic angle spinning (HRMAS) NMR spectroscopy was used to study the effect of mixed solvent systems on the acidity at the solid−liquid interface of solid acid catalysts. A method was developed that can exploit benefits of both solution and solid-state NMR (SSNMR) by wetting porous solids with small volumes of liquids (<2 >μL/mg) to create an interfacial liquid that exhibits unique motional dynamics intermediate to an isotropic liquid and a rigid solid. Results from these experiments provide information about the influence of the solvent mixtures on the acidic properties at a solid−liquid interface. Importantly, use of MAS ...


Electropolymerized Pyrrole Based Conductive Polymeric Ionic Liquids And Their Application For Solid-Phase Microextraction, Amila M. Devasurendra, Cheng Zhang, Joshua A. Young, L. M. Viranga Tillekeratne, Jared L. Anderson, Jon R. Kirchoff Jul 2017

Electropolymerized Pyrrole Based Conductive Polymeric Ionic Liquids And Their Application For Solid-Phase Microextraction, Amila M. Devasurendra, Cheng Zhang, Joshua A. Young, L. M. Viranga Tillekeratne, Jared L. Anderson, Jon R. Kirchoff

Chemistry Publications

Pyrrole was covalently bonded to 1-methyl and 1-benzylimidazolium ionic liquids (ILs) via an N-substituted alkyl linkage to prepare electropolymerizable IL monomers with excellent thermal stability. The methylimidazolium IL, [pyrrole-C6MIm]+, was then electropolymerized on macro- and microelectrode materials to form conductive polymeric IL (CPIL)-modified surfaces. Electrochemical characterization of a 1.6 mm diameter Pt disk electrode modified with poly[pyrrole-C6MIm]+ demonstrated a selective uptake for an anionic redox probe while rejecting a cationic redox probe. Furthermore, electropolymerization of [pyrrole-C6MIm]+ doped with single-walled carbon nanotubes (SWNT) on 125 μm platinum wires produced 42 μm thick poly[pyrrole-C6MIm]+/SWNT films compared to ...


Packing Of Russian Doll Clusters To Form A Nanometer-Scale Cscl-Type Compound In A Cr–Zn–Sn Complex Metallic Alloy, Weiwei Xie, Robert J. Cava, Gordon J. Miller Jul 2017

Packing Of Russian Doll Clusters To Form A Nanometer-Scale Cscl-Type Compound In A Cr–Zn–Sn Complex Metallic Alloy, Weiwei Xie, Robert J. Cava, Gordon J. Miller

Chemistry Publications

The new complex intermetallic alloy, Cr22Zn72Sn24, with a giant cubic unit cell (space group Fmc, Z = 8, Pearson symbol cF944 with a = 25.083(3) Å) is reported. The structure can be described as a CsCl-type packing of two “Russian Doll” type intermetallic clusters: a 99-atom cluster, Cr@(Cr8Zn6)(Sn)24(Zn)60, composed of a central Cr atom encapsulated by three shells: a distorted rhombic dodecahedron, a snub-cube, and a rhombi-icosidodecahedron; and a 55-atom cluster, Cr@(Zn)12(Zn)30(Zn)12, also composed of a central Cr atom, but now surrounded by three different shells: an icosahedron, an ...


High-Throughput Selective Capture Of Single Circulating Tumor Cells By Dielectrophoresis At A Wireless Electrode Array, Robbyn Anand, Min Li Jun 2017

High-Throughput Selective Capture Of Single Circulating Tumor Cells By Dielectrophoresis At A Wireless Electrode Array, Robbyn Anand, Min Li

Chemistry Publications

We demonstrate continuous high-throughput selective capture of circulating tumor cells by dielectrophoresis at arrays of wireless electrodes (bipolar electrodes, BPEs). The use of BPEs removes the requirement of ohmic contact to individual array elements, thus enabling otherwise unattainable device formats. Capacitive charging of the electrical double layer at opposing ends of each BPE allows an AC electric field to be transmitted across the entire device. Here, two such designs are described and evaluated. In the first design, BPEs interconnect parallel microchannels. Pockets extruding from either side of the microchannels volumetrically control the number of cells captured at each BPE tip ...