Article
Biochemical Research Methods
Joshua Casto, Xiaowei Bogetti, Hannah R. Hunter, Zikri Hasanbasri, Sunil Saxena
Summary: The narrow excitation bandwidth of monochromic pulses limits the sensitivity of pulsed dipolar spectroscopy on Cu(II)-based measurements. To overcome this limitation, frequency-swept pulses with large excitation bandwidths have been used. In this study, we demonstrate the effectiveness of chirp pulses on commercial instrumentation for Cu(II) distance measurements, and discuss the sensitivity considerations for robust distance measurements using Cu(II) labels in proteins. We show that a sweeping bandwidth chirp pulse can significantly improve the sensitivity of long-range distance measurements, while the sensitivity of short-range distances only slightly increases due to specific considerations for the chirp pulse duration.
JOURNAL OF MAGNETIC RESONANCE
(2023)
Article
Computer Science, Interdisciplinary Applications
Adeel Ikram, Hyun Chung
Summary: A numerical model was developed to investigate the influence of pulse frequency on the metal transfer mode, dynamics, and thermal behavior in the pulsed wire-arc additive manufacturing process. The results show that only the current pulses with a medium frequency regime achieve the one-droplet-per-pulse mode of metal transfer. An increase in pulse frequency leads to a shorter necking length of the pendent droplet and a significantly lower average speed and temperature of the detached droplet.
JOURNAL OF COMPUTATIONAL DESIGN AND ENGINEERING
(2022)
Article
Materials Science, Multidisciplinary
Jicheng Chen, Xiaomei Chen, Xuejun Liu, Yanhong Wei
Summary: A multi-phase and multi-physics coupling model was proposed and experimentally verified for the pulsed laser beam welding of Ti6Al4V titanium alloy. The welding dynamics were found to go through three stages - keyhole formation/rebuilding, keyhole shrinking, and keyhole collapsing. Keyhole collapsing induced porosities in the lower weld pool, which could be non-contact or captured by the liquid-solid interface. Compensation flows and oscillatory growth were observed in the keyhole and weld pool. The pulse frequency had significant effects on the weld pool dimensions and the welding formation.
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
(2022)
Article
Engineering, Electrical & Electronic
K. Takemura, K. Sudo, R. Dorget, J. L. Dadiel, M. Sakafuji, K. Yokoyama, T. Oka, M. Murakami, N. Sakai
Summary: This study investigated the conditions for obtaining high-quality superconducting joint to a Gd-Ba-Cu-O bulk superconductor and explored the effects and effectiveness of pulse field magnetization (PFM). A good superconducting joint was fabricated using the local melting method, and the PFM method was applied to the joined bulk. The results showed that a high magnetic field of 1.2 T was trapped in the joined part, and the evaluation of the J(c)-B characteristics confirmed the efficient magnetization of the joined sample.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2023)
Article
Radiology, Nuclear Medicine & Medical Imaging
Pedram Noormohammadpour, Amir Hooshang Ehsani, Farshad Farnaghi, Hassan Seirafi, Seyed Alamdar Bagherinia, Parvaneh Hatami, Azadeh Goodarzi, Zeinab Aryanian
Summary: This study aimed to investigate the effectiveness of hair removal using an alexandrite laser with different pulse durations. The results showed that both 3 and 10 milliseconds pulse durations had a 56% clearance rate with no significant difference in clinical efficacy or side effects. The 755 nm alexandrite laser is an effective and safe method for delaying hair regrowth, regardless of the pulse duration.
JOURNAL OF LASERS IN MEDICAL SCIENCES
(2021)
Article
Chemistry, Physical
Yani Zhang, Yue Peng, Junhua Li, Kyle Groden, Jean-Sabin Mcewen, Eric D. Walter, Ying Chen, Yong Wang, Feng Gao
Article
Chemistry, Analytical
Sayandev Chatterjee, Vanessa E. Holfeltz, Gabriel B. Hall, Isaac E. Johnson, Eric D. Walter, Sungsik Lee, Benjamin Reinhart, Wayne W. Lukens, Nicholas P. Machara, Tatiana G. Levitskaia
ANALYTICAL CHEMISTRY
(2020)
Article
Chemistry, Multidisciplinary
Jotheeswari Kothandaraman, Johnny Saavedra Lopez, Yuan Jiang, Eric D. Walter, Sarah D. Burton, Robert A. Dagle, David J. Heldebrant
Summary: The integrated carbon capture and conversion process successfully converts captured CO2 into hydrocarbons, mainly methane, using a water-lean solvent and a heterogeneous Ru catalyst. Technoeconomic analysis shows that this process can improve thermal efficiency, reduce total capital investment, and lower the selling price of synthetic natural gas, highlighting its energetic and economic benefits.
Article
Chemistry, Physical
Eric D. Walter, Cigdem Capan, Amanda J. Casella, Jennifer C. Carter, Bruce K. McNamara, Chuck Z. Soderquist, Sergey Sinkov, Richard A. Clark, Forrest D. Heller, Lucas E. Sweet, Jordan F. Corbey, Herman Cho
Summary: Fluorine-19 magnetic shielding tensors have been measured in a series of actinide tetrafluorides by solid state nuclear magnetic resonance spectroscopy, revealing pronounced deviations from predictions based on localized valence electron models. This suggests that these compounds can serve as an attractive choice for a systematic study of the variation in the electronic structure across the 5f row of the Periodic Table.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Multidisciplinary Sciences
Ruozhu Feng, Xin Zhang, Vijayakumar Murugesan, Aaron Holias, Ying Chen, Yuyan Shao, Eric Walter, Nadeesha P. N. Wellala, Litao Yan, Kevin M. Rosso, Wei Wang
Summary: The research shows that molecular engineering of fluorenone enables alcohol electro-oxidation without the use of a catalyst at room temperature, allowing for reversible ketone hydrogenation and dehydrogenation reactions. Flow batteries based on this technology operate efficiently in a non-demanding environment, exhibiting stable cycling performance at ambient and mildly increased temperatures. This expands the application range of organic active materials and suggests potential for identifying other promising organic redox couple candidates.
Article
Chemistry, Physical
Jun-Kun Lai, Nicholas R. Jaegers, Bar Mosevitzky Lis, Mingyu Guo, Michael E. Ford, Eric Walter, Yong Wang, Jian Zhi Hu, Israel E. Wachs
Summary: Supported V2O5-WO3/TiO2 materials are employed as SCR catalysts for NOx emission control. The surface WOx sites stabilize the TiO2 phase, while the surface VOx sites mainly exist as V-5+O-x sites. The concentration of surface NH3* species is lower in hydrothermally treated catalysts, but SCR activity is comparable to calcined catalysts.
Article
Chemistry, Inorganic & Nuclear
Dumitru-Claudiu Sergentu, Frederic Gendron, Eric D. Walter, Sejun Park, Cigdem Capan, R. Gian Surbella, Chuck Z. Soderquist, Gabriel B. Hall, Sergey I. Sinkov, Jochen Autschbach, Herman Cho
Summary: In this study, electric field gradient tensors in the equatorial plane of the UO22+ ion were measured and computed using NMR, NQR, and relativistic Kohn-Sham methods. The results suggest that the field gradient principal axes are sensitive to the ligand's electron donation and the environment model.
INORGANIC CHEMISTRY
(2022)
Article
Biochemistry & Molecular Biology
John H. H. Enemark
Summary: Molybdenum enzymes, with their unique molybdenum cofactor, play important roles in biological systems. This article presents the structures and properties of molybdenum enzymes, as well as the development of a new notation system to describe the redox states of the molybdenum cofactor. The different electron distributions utilized by sulfite oxidase and xanthine oxidase during catalysis are also discussed.
JOURNAL OF INORGANIC BIOCHEMISTRY
(2022)
Article
Chemistry, Physical
Kee Sung Han, Sarah D. Burton, Eric D. Walter, Yongsoon Shin, Wenbin Kuang, Kevin L. Simmons
Summary: This study investigated the microsized pore parameters and xenon diffusion in model EPDM rubbers under pressure. The results suggest that the xenon atoms interact with almost the entire pore surface, while still being able to flow through narrow diffusion/exchange channels between pores. The diffusion and exchange of xenon between the pore and outer surface are prolonged. The composition of the rubber affects the pore and exchange distances, and reducing the size of cracks and gas penetration depth can enhance the rubber's performance as a high-pressure gas barrier.
JOURNAL OF PHYSICAL CHEMISTRY B
(2022)
Article
Chemistry, Multidisciplinary
Yiqing Wu, Yue Ma, Yilin Wang, Kenneth G. Rappe, Nancy M. Washton, Yong Wang, Eric D. Walter, Feng Gao
Summary: This study investigates the key factors controlling the low-temperature NH3-SCR reaction using Cu/SSZ-13 catalysts. The kinetics of Cu loading and the dynamics of Cu ions are found to strongly affect the SCR reaction. Operando EPR spectroscopy reveals a strong correlation between Cu-ion dynamics and SCR kinetics.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Chemistry, Multidisciplinary
Geoffrey M. Bowers, Sydney S. Cunniff, H. Todd Schaef, Sarah D. Burton, Eric D. Walter, David W. Hoyt, John S. Loring
Summary: This paper examines the interaction between wet and dry supercritical CO2 and saturated smectite clays, and finds that the polarizability of the charge-balancing cation plays an important role in determining the interlayer fluid properties and smectite expansion.
Article
Chemistry, Multidisciplinary
Eric D. Walter, Difan Zhang, Ying Chen, Kee Sung Han, J. David Bazak, Sarah Burton, Kathryn O'Harra, David W. Hoyt, Jason E. Bara, Deepika Malhotra, Sarah I. Allec, Vassiliki-Alexandra Glezakou, David J. Heldebrant, Roger Rousseau
Summary: Efficient direct air capture (DAC) of CO2 can be achieved by using a combination of a CO2-selective membrane and a CO2 capture solvent. The interaction between a water-lean carbon-capture solvent, a PEEK-ionene membrane, and CO2 was studied using advanced NMR techniques and simulations. It was found that the solvent provides a thermodynamic and kinetic pathway for CO2 to be drawn through the membrane, enhancing its performance. The reaction between the solvent and CO2 also creates structural changes that facilitate faster CO2 diffusion at the interface.
Article
Multidisciplinary Sciences
Yiqing Wu, Wenru Zhao, Sang Hyun Ahn, Yilin Wang, Eric D. Walter, Ying Chen, Miroslaw A. Derewinski, Nancy M. Washton, Kenneth G. Rappe, Yong Wang, Donghai Mei, Suk Bong Hong, Feng Gao
Summary: Support Bronsted acid strength and density have a significant influence on the low temperature NH3-SCR over Cu-exchanged small pore zeolite catalysts. The presence of Bronsted acid sites promotes the hydrolysis and intercage transfer of Cu-II(NH3)(4) intermediates. Cu-ion active sites solvated by NH3 play a crucial role in the NH3-SCR reaction, with the key reaction steps involving hydrolysis of Cu-II(NH3)(4) ion to Cu-II(OH)(NH3)(3) ion and the intercage transfer of Cu-II(OH)(NH3)(3) ion. The support Bronsted acid strength and density affect the energetics of these reaction steps, leading to variations in Cu atomic efficiency among different zeolite catalysts.
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Physical
Sejun Park, Eric D. Walter, Chuck Z. Soderquist, Sergey I. Sinkov, Herman Cho
Summary: We conducted a study on the temperature dependence of Cl-35 nuclear quadrupole resonance (NQR) transition energies and spin-lattice relaxation times (T-1) for U-235-depleted dicesium uranyl tetrachloride (Cs2UO2Cl4). The research aimed to investigate the electronic interactions between the uranium center and atoms in the equatorial plane of the UO22+ ion. The results showed that the transition frequency decreases slowly below 75 K, while its linear dependence becomes more rapid above this temperature. The spin-lattice relaxation time becomes shorter with temperature, with a nearly quadratic decrease as temperatures increase. The study suggests that these trends can be explained by phonon-induced fluctuations of the electric field gradient tensor and partial electron delocalization from Cl to U. The theoretical model's fit to the experimental data estimated a Debye temperature of 96 K. Additionally, the study examines the application of this approach in investigating covalency in actinide-ligand bonding.
JOURNAL OF PHYSICAL CHEMISTRY A
(2023)
Article
Chemistry, Multidisciplinary
Arun Ramanathan, Eric D. Walter, Martin Mourigal, Henry S. La Pierre
Summary: The crystal field control of rare-earth ions is used to reduce decoherence in qubits and enhance the effective barrier of single-molecule magnets. By controlling the oxidation state of the rare-earth ions, the magnitude of the crystal field can be increased. This study focuses on the effects of symmetry on dynamic magnetic properties and demonstrates the chemically tunable single-ion spin-orbit coupled states in Pr4+-doped perovskite oxide lattices.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
