3,605 results on '"Range (particle radiation)"'
Search Results
2. Halogen-Ion-Induced Structural Phase Transition Giving a Polymorph of HgBr2 with Balanced Nonlinear Optical Properties
- Author
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Jie Ma, Yanjun Li, Can Yang, Qi Wu, and Xian Liu
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Inorganic Chemistry ,Nonlinear optical ,Structural phase ,Range (particle radiation) ,Chemistry ,Infrared ,Phase (matter) ,Halogen ,Crystal structure ,Physical and Theoretical Chemistry ,Molecular physics ,Ion - Abstract
The key to developing new infrared nonlinear optical (NLO) materials is balancing second-order nonlinear optical effects and the laser-induced damage threshold (LIDT). In this paper, a new polymorph of HgBr2 (P212121) was synthesized by a "halogen-ion-induced effect" in solution, which features a crystal structure different from that of the original phase (Cmc21) and exhibits better NLO properties. Its powders show a strong SHG effect (9 × KDP), a high LIDT (30 × AgGaS2), a wide infrared transparent range, and stability in air, making it a prospective NLO material in the IR region. In addition, the above excellent NLO characteristics are well illustrated in DFT theoretical calculations. More importantly, experimental results show that the new infrared NLO polymorph with excellent comprehensive properties could be controllably obtained by using the halogen-ion-induced strategy.
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- 2021
3. Synergy of Valence Band Modulation and Grain Boundary Engineering Leading to Improved Thermoelectric Performance in SnTe
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Di Wu, Jiaqing He, Yong Yu, Baopeng Ma, Zupei Yang, Jicheng Wang, Xiaolian Chao, and Jitong Wang
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Range (particle radiation) ,Materials science ,Condensed matter physics ,Energy Engineering and Power Technology ,Thermoelectric materials ,Lattice thermal conductivity ,Modulation ,Thermoelectric effect ,Materials Chemistry ,Electrochemistry ,Valence band ,Chemical Engineering (miscellaneous) ,Intermediate temperature ,Grain boundary ,Electrical and Electronic Engineering - Abstract
SnTe is a lead-free and promising p-type thermoelectric material in an intermediate temperature range (500–900 K), but its intrinsic performance is poor due to excess cation vacancies and relativel...
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- 2021
4. Overcharging and Free Energy Barriers for Equally Charged Surfaces Immersed in Salt Solutions
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Jan Forsman and Samuel Stenberg
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Range (particle radiation) ,Materials science ,Charge density ,Charge (physics) ,Surfaces and Interfaces ,Condensed Matter Physics ,Article ,Effective nuclear charge ,Charged particle ,Condensed Matter::Soft Condensed Matter ,Chemical physics ,Electrochemistry ,Coulomb ,DLVO theory ,General Materials Science ,Surface charge ,Spectroscopy - Abstract
The stability of dispersions containing charged particles may obviously be regulated by salt. In some systems, the effective charge, as measured by the potential some small distance away from the particles, can have a sign opposite to the bare surface charge. If charge reversal takes place, there is typically a salt concentration regime within which colloidal stability increases with added salt. These experimental findings on dispersions have been corroborated by atomic force microscopy investigations, where an attraction is found at short separations. This attraction is stronger than expected from standard DLVO theory, and there has been considerable debate concerning its origin. In this work, we use simple coarse-grained models of these systems, where the bare surfaces carry a uniform charge density, and ion-specific adsorption is absent. Our hypothesis is that these experimental observations can be explained by such a simplistic pure Coulomb based model. Our approach entails grand canonical Metropolis Monte Carlo (MC) simulations as well as correlation-corrected Poisson-Boltzmann (cPB) calculations. In the former case, all ions have a common size, while the cPB utilizes a point-like model. We devote significant attention on apparent surface charge densities and interactions between large flat model surfaces immersed in either a 2:1 salt or a 3:1 salt. In contrast to most of the previous theoretical efforts in this area, we mainly focus on the weak long-ranged repulsion and its connection to an effective surface charge. We find a charge reversal and a concomitant development of a free energy barrier for both salts. The experimentally observed nonmonotonic dependence of colloidal stability on the salt concentration is reproduced using MC simulations as well as cPB calculations. A strong attraction is observed at short range for all investigated cases. We argue that in our model, all non-DLVO aspects can be traced to ion–ion correlations.
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- 2021
5. Phonon Bottleneck in Temperature-Dependent Hot Carrier Relaxation in Graphene Oxide
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Arvind Singh and Sunil Kumar
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Range (particle radiation) ,Materials science ,Condensed matter physics ,Phonon ,Graphene ,Time evolution ,Oxide ,Physics::Optics ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,law.invention ,Condensed Matter::Materials Science ,chemistry.chemical_compound ,General Energy ,chemistry ,law ,Physics::Atomic and Molecular Clusters ,Relaxation (physics) ,Physics::Chemical Physics ,Physical and Theoretical Chemistry ,Ultrashort pulse - Abstract
We report temperature-dependent ultrafast hot carrier relaxation in graphene oxide (GO). At all temperatures in the range from ∼6 to 400 K, the time evolution of the photoexcited relaxation reveals...
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- 2021
6. Classical Electrostatics Remains the Driving Force for Interanion Hydrogen and Halogen Bonding
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Shiwei Yin, Changwei Wang, Yirong Mo, Qiuyan Feng, and Li Chen
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Range (particle radiation) ,Halogen bond ,Force field (physics) ,Hydrogen bond ,Chemistry ,Chemical physics ,Binding energy ,Cooperativity ,Physical and Theoretical Chemistry ,Electrostatics ,Dissociation (chemistry) - Abstract
Interanion hydrogen bonding (IAHB) and halogen bonding (IAXB) have emerged as a counterintuitive linker in a range of fascinating applications. Despite the overall repulsive (positive) binding energy, anions are trapped in a local minimum with its corresponding transition state (TS) preventing dissociation. In other words, the adduct of anions is metastable. Seemingly, the electrostatic paradigm and force field description of hydrogen/halogen bonding (HB/XB) are challenged, because of the preconceived Coulombic repulsion. Aiming at an insightful understanding of these interanion phenomena, we employed the energy decomposition approach based on the block-localized wavefunction method (BLW-ED) to investigate a series of exemplary interanion complexes. As expected, the key distinction from the conventional HB/XB lies in the electrostatic interaction, which is not increasingly repulsive as anions gradually approach to each other. Rather, there is a Coulombic barrier at a certain point. After this point, the electrostatic repulsion diminishes with the decreasing distance between anions. Differently, other energy components vary monotonically just like in conventional cases. The nonmonotonic characteristic of the electrostatic interaction in interanion complexes was reproduced using the multipole expansion in AMOEBA polarizable force field in which the state-specified atomic multipoles were adopted. This suggests that the nonmonotonicity can be well interpreted by classical electrostatic theory and there is no conceptual difference between conventional HB/XB and IAHB/IAXB. The stability of IAHB/IAXB depends on the competition between the local attractive HB/XB and the global Coulombic repulsion of net charges, though there is cooperativity between these two contrasting forces. This concise model was supported by the attractive IAHB/IAXB in modified molecular capsules, which exhibit strong quadruple HB/XBs and a considerable distance between charged substituents.
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- 2021
7. Photodissociation Dynamics of Methyl Hydroperoxide at 193 nm: A Trajectory Surface-Hopping Study
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Prabhash Mahata and Biswajit Maiti
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Range (particle radiation) ,Chemistry ,Potential energy surface ,Photodissociation ,Degenerate energy levels ,Surface hopping ,Singlet state ,Physical and Theoretical Chemistry ,Conical intersection ,Molecular physics ,Dissociation (chemistry) - Abstract
The photodissociation of methyl hydroperoxide (CH3OOH) at 193 nm has been studied using a direct dynamics trajectory surface-hopping (TSH) method. The potential energies, energy gradients, and nonadiabatic couplings are calculated on the fly at the MRCIS(6,7)/aug-cc-pVDZ level of theory. The hopping of a trajectory from one electronic state to another is decided on the basis of Tully's fewest switches algorithm. An analysis of the trajectories reveals that the cleavage of the weakest O-O bond leads to major products CH3O(2E) + OH(2Π), contributing about 72.7% of the overall product formation. This OH elimination was completed in the ground degenerate product state where both the ground singlet (S0) and first excited singlet (S1) states become degenerate. The O-H bond dissociation of CH3OOH is a minor channel contributing about 27.3% to product formation, resulting in products CH3OO + H. An inspection of the trajectories indicates that unlike the major channel OH elimination, the H-atom elimination channel makes a significant contribution (∼3% of the overall product formation) through the nonadiabatic pathway via conical intersection S1/S0 leading to ground-state products CH3OO(X 2A″) + H(2S) in addition to adiabatic dissociation in the first excited singlet state, S1, correlating to products CH3OO(1 2A') + H(2S). The computed translational energy of the majority of the OH products is found to be high, distributed in the range of 70 to 100 kcal/mol, indicating that the dissociation takes place on a strong repulsive potential energy surface. This finding is consistent with the nature of the experimentally derived translational energy distribution of OH with an average translational energy of 67 kcal/mol after the excitation of CH3OOH at 193 nm.
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- 2021
8. Gating of Substrate Access and Long-Range Proton Transfer in Escherichia coli Nitrate Reductase A: The Essential Role of a Remote Glutamate Residue
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Axel Magalon, Frédéric Biaso, Julia Rendon, Stéphane Grimaldi, Farida Seduk, Marlon Sidore, Bruno Guigliarelli, Sinan Al-Attar, Jean-Pierre Duneau, Laboratoire de chimie bactérienne (LCB), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Bioénergétique et Ingénierie des Protéines (BIP ), Laboratoire d'ingénierie des systèmes macromoléculaires (LISM), Aix Marseille Université (AMU)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Ingéniérie et Science des Matériaux - EA 4695 (LISM), Université de Reims Champagne-Ardenne (URCA)-SFR Condorcet, Université de Reims Champagne-Ardenne (URCA)-Université de Picardie Jules Verne (UPJV)-Centre National de la Recherche Scientifique (CNRS)-Université de Reims Champagne-Ardenne (URCA)-Université de Picardie Jules Verne (UPJV)-Centre National de la Recherche Scientifique (CNRS), ANR-11-IDEX-0001,Amidex,INITIATIVE D'EXCELLENCE AIX MARSEILLE UNIVERSITE(2011), LEROI, Delphine, INITIATIVE D'EXCELLENCE AIX MARSEILLE UNIVERSITE - - Amidex2011 - ANR-11-IDEX-0001 - IDEX - VALID, Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU), Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Aix Marseille Université (AMU), and Université de Reims Champagne-Ardenne (URCA)-Centre National de la Recherche Scientifique (CNRS)-Université de Reims Champagne-Ardenne (URCA)-Centre National de la Recherche Scientifique (CNRS)
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0303 health sciences ,Range (particle radiation) ,Proton ,Chemistry ,[SDV]Life Sciences [q-bio] ,Glutamate receptor ,Substrate (chemistry) ,General Chemistry ,Gating ,010402 general chemistry ,Nitrate reductase ,medicine.disease_cause ,01 natural sciences ,Catalysis ,0104 chemical sciences ,[SDV] Life Sciences [q-bio] ,03 medical and health sciences ,Residue (chemistry) ,Biophysics ,medicine ,Escherichia coli ,030304 developmental biology - Abstract
International audience; The Mo/W-bisPGD enzyme superfamily comprises a vast number of mononuclear molybdenum and tungsten enzymes that catalyze a great diversity of vital reactions in prokaryotes. In the past decades, much attention has been devoted to the immediate surroundings of the metal atom highlighting the importance of the inner coordination sphere but has failed to identify molecular determinants of the reactivity. Here, we report the mechanistic importance of a set of conserved residues that line the substrate entry tunnel in Escherichia coli nitrate reductase A (Nar), a paradigmatic enzyme of the Mo/W-bisPGD superfamily. Using mutagenesis, enzyme kinetics, electron paramagnetic resonance spectroscopy, and molecular dynamics, we unveil the pivotal role of Glu-581 motion and a number of polar residues in its close proximity in substrate affinity and proton transfer to the Mo active site. Motion of the side chain of Glu-581 exhibiting a strong acid–base cooperativity with Asp-801 and surrounded by several polar interactions controls the hydration inside the protein core, proton transfer, and substrate selectivity toward the active site. Overall, we identify an additional determinant that fine-tunes the reactivity and selectivity in Nar and propose that a gating mechanism is at play in several other members of the superfamily.
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- 2021
9. PbI2–TiO2 Bulk Heterojunctions with Long-Range Ordering for X-ray Detectors
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Chengce Lin, Wenbo Ma, Yujing Liu, Jie Ren, Chong Hu, Quan Wen, Xinyi Jin, Hanying Li, and Yang Michael Yang
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Range (particle radiation) ,Materials science ,business.industry ,Exciton dissociation ,Detector ,X-ray detector ,Photodetector ,Heterojunction ,Electron ,Optoelectronics ,General Materials Science ,Physical and Theoretical Chemistry ,business ,Electronic properties - Abstract
High-performance X-ray detectors are usually based on single crystals, due to the long-range ordering and hence outstanding electronic properties. On the other hand, bulk heterojunctions (BHJs) that can effectively enhance photogenerated exciton dissociation are widely used for photodetectors. The benefits of both spur investigation into how to combine these two strategies to enhance X-ray detection. Here, TiO2 networks are incorporated into PbI2 crystals to form interpenetrating type II heterojunctions, namely BHJs. These BHJs exhibit long-range ordering in molecular packing similar to that of single crystals. Compared with single crystals, the long-range ordered BHJs facilitate the separation of photogenerated electrons and holes to inhibit recombination, extend the mobility lifetime product by 6.4 times, and consequently improve X-ray sensitivity by 5.8 times. Hence, this work provides a new strategy using gel-grown crystals to fabricate high-performance X-ray detectors as well as a new platform for studying the behavior of X-ray-generated carriers in BHJs with long-range ordering.
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- 2021
10. Preparation of MFI Nanosheets with Distinctive Microstructures via Facile Alkaline Etching
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Yi Liu, Taotao Ji, Tianli Zhou, Jinming Lu, and Hong Li
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Range (particle radiation) ,Alkaline etching ,Materials science ,Chemical engineering ,General Chemical Engineering ,General Chemistry ,Microstructure ,Zeolite ,Industrial and Manufacturing Engineering - Abstract
Although zeolite nanosheets (NSs) exhibit great prospects for a wide range of applications due to microstructural superiority, their facile preparation and microstructural tailoring remain a great ...
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- 2021
11. Novel Bending Sensor Based on a Solution-Processed Cu2O Film with High Resolution Covering a Wide Curvature Range
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Ryosuke Nitta, Atsushi Shishido, Tetsuo Kishi, Ryo Taguchi, Yuta Kubota, and Nobuhiro Matsushita
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Range (particle radiation) ,Materials science ,business.industry ,General Chemical Engineering ,High resolution ,General Chemistry ,Bending ,Curvature ,Article ,Solution processed ,Chemistry ,Optics ,business ,QD1-999 - Abstract
A Cu2O film is prepared on a flexible polyethylene terephthalate substrate for a bending sensor using the spin–spray method, a facile and low-environmental-load solution process. The Cu2O bending sensor shows high sensitivity and high resolution not only over a wide range of curvatures (0 < κ < 0.21 mm–1) but also for very small curvature changes (Δκ = ∼ 0.03 mm–1). The bending response of the sensor exhibited a curvature change of high linearity with a good gauge factor (18.2) owing to the grain-boundary resistance and piezoresistive effects of the fabricated Cu2O film. In addition, the sensor possesses good repeatability, stability, and long-term (>30 days) and mechanical fatigue durability (1000 bending–release cycles). The sensor is capable of detailed monitoring of large- and small-scale human motions, such as finger bending, wrist bending, nodding, mouth opening/closing, and swallowing. In addition, excellent stability and repeatability of the monitoring performance is observed over a wide range of motion angles and speeds. All of these results demonstrate the potential of the flexible bending sensor based on the Cu2O film as a candidate for healthcare monitoring and wearable electronics.
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- 2021
12. Long-Range Metal–Ligand Cooperation by Iron Hydride Complexes Bearing a Phenanthroline-Based Tetradentate PNNP Ligand
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Monika Gautam, Shinji Tanaka, Akira Sekiguchi, and Yumiko Nakajima
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Range (particle radiation) ,Iron hydride ,Bearing (mechanical) ,Ligand ,Phenanthroline ,Organic Chemistry ,law.invention ,Inorganic Chemistry ,Metal ,chemistry.chemical_compound ,chemistry ,law ,visual_art ,Polymer chemistry ,visual_art.visual_art_medium ,Physical and Theoretical Chemistry - Published
- 2021
13. Fluoride-Induced Negative Differential Resistance in Nanopores: Experimental and Theoretical Characterization
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Salvador Mafe, Javier Cervera, Mubarak Ali, Jose J. Perez-Grau, Wolfgang Ensinger, Vladimir García-Morales, Saima Nasir, and Patricio Ramirez
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Range (particle radiation) ,Materials science ,Nanotecnologia ,Conductance ,Conical surface ,Thermal conduction ,Threshold voltage ,symbols.namesake ,Nanopore ,Chemical physics ,symbols ,General Materials Science ,Materials ,Order of magnitude ,Debye length - Abstract
We describe experimentally and theoretically the fluoride-induced negative differential resistance (NDR) phenomena observed in conical nanopores operating in aqueous electrolyte solutions. The threshold voltage switching occurs around 1 V and leads to sharp current drops in the nA range with a peak-to-valley ratio close to 10. The experimental characterization of the NDR effect with single pore and multipore samples concern different pore radii, charge concentrations, scan rates, salt concentrations, solvents, and cations. The experimental fact that the effective radius of the pore tip zone is of the same order of magnitude as the Debye length for the low salt concentrations used here is suggestive of a mixed pore surface and bulk conduction regime. Thus, we propose a two-region conductance model where the mobile cations in the vicinity of the negative pore charges are responsible for the surface conductance, while the bulk solution conductance is assumed for the pore center region.
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- 2021
14. Cu(II)-Promoted Cascade Synthesis of Fused Imidazo-Pyridine-Carbonitriles
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Anjali Dahiya, Tipu Alam, Bhisma K. Patel, Hirendra Nath Dhara, and Amitava Rakshit
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Range (particle radiation) ,Photoluminescence ,Molecular Structure ,Pyridines ,Band gap ,Chemistry ,Organic Chemistry ,Imidazoles ,Substrate (chemistry) ,Crystallography ,chemistry.chemical_compound ,Cyclization ,Pyridine ,Absorption (electromagnetic radiation) ,Maxima ,Basis set - Abstract
A Cu(II)-promoted synthesis of an aza-fused N-heterocycle having a benz-imidazopyridine scaffold is developed via an addition-cyclization reaction followed by an Ullmann-type C-N coupling between o-iodoanilines and γ-ketodinitriles. This protocol features a broad substrate scope, giving products in 32-84% yields. The compounds show excellent photoluminescence properties having two absorption maxima in the region between 270-280 and 338-350 nm and emission maxima in the range of 502-533 nm. The HOMO-LUMO energy gap of 3.49-3.57 eV was determined using Gaussian 09 at the B3LYP/6-31G (d, p) basis set level. We also demonstrated a few postsynthetic modifications.
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- 2021
15. Effect of Dipole Mobility in Secondary Crystals on Piezoelectricity of a Poly(vinylidene fluoride-co-trifluoroethylene) 52/48 mol % Random Copolymer with an Extended-Chain Crystal Structure
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Hezhi He, Ruipeng Li, Zhiwen Zhu, Guanchun Rui, and Lei Zhu
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Range (particle radiation) ,Materials science ,Polymers and Plastics ,business.industry ,Organic Chemistry ,Crystal structure ,Piezoelectricity ,Inorganic Chemistry ,chemistry.chemical_compound ,Dipole ,chemistry ,Chain (algebraic topology) ,Materials Chemistry ,Copolymer ,Optoelectronics ,business ,Fluoride ,Piezoelectric polymer - Abstract
High-performance piezoelectric polymers are promising for a broad range of practical applications, such as sensors, actuators, and energy generators in medical devices, wearable electronics, and so...
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- 2021
16. Ni(OH)2 Nanosheets Modified Hexagonal Pyramid CdS Formed Type II Heterojunction Photocatalyst with High-Visible-Light H2 Evolution
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Qi Feng, Jianfeng Huang, Zhang Hao, Yu Fan, Yong Wang, Changqing Liu, Xingang Kong, and Lixiong Yin
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Range (particle radiation) ,Materials science ,Energy Engineering and Power Technology ,Hexagonal pyramid ,Heterojunction ,Photochemistry ,Materials Chemistry ,Electrochemistry ,Photocatalysis ,Chemical Engineering (miscellaneous) ,Electrical and Electronic Engineering ,Electronic band structure ,Visible spectrum ,Hydrogen production - Abstract
CdS has a wide visible-light response range and suitable energy band structure; it has been spotlighted in the field of photocatalysis. Nevertheless, its poor photogenerated carriers separation eff...
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- 2021
17. Shortening Droplet Contact Time over a Wider Impact Velocity Range by Molding Flexible Nanohairs and Substrates
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Hui-Long Huang and Han-Xiong Huang
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Range (particle radiation) ,Impact velocity ,Materials science ,Polymers and Plastics ,Contact time ,Process Chemistry and Technology ,Organic Chemistry ,Molding (process) ,Composite material - Published
- 2021
18. Enhanced Water Nucleation and Growth Based on Microdroplet Mobility on Lubricant-Infused Surfaces
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Xinyu Jiang, Patricia B. Weisensee, and Jianxing Sun
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Range (particle radiation) ,Materials science ,Condensation ,Fluid Dynamics (physics.flu-dyn) ,Nucleation ,FOS: Physical sciences ,Applied Physics (physics.app-ph) ,Physics - Fluid Dynamics ,Physics - Applied Physics ,Surfaces and Interfaces ,Condensed Matter Physics ,Subcooling ,Viscosity ,Chemical physics ,Heat transfer ,Electrochemistry ,General Materials Science ,Redistribution (chemistry) ,Lubricant ,Spectroscopy - Abstract
Lubricant-infused surfaces (LISs) can promote stable dropwise condensation and improve heat transfer rates due to a low nucleation free-energy barrier and high droplet mobility. Topographical differences in the oil surface cause water microdroplets to rigorously self-propel long distances, continuously redistributing the oil film and potentially refreshing the surface for re-nucleation. Using high-speed microscopy, we reveal that during water condensation on LISs, the smallest visible droplets (diameter ~ 1um, qualitatively representing nucleation) predominantly emerge in oil-poor regions due to a smaller thermal activation barrier. Considering the significant heat transfer performance of microdroplets (< 10um) and transient characteristic of microdroplet movement, we compare the apparent nucleation rate density and water collection rate for LISs with oils of different viscosity and a solid hydrophobic surface at a wide range of subcooling temperatures. Generally, the lowest lubricant viscosity leads to the highest nucleation rate density. We characterize the length and frequency of microdroplet movement and attribute the nucleation enhancement primarily to higher droplet mobility and surface refreshing frequency. Interestingly and unexpectedly, hydrophobic surfaces outperform high-viscosity LISs at high subcooling temperatures, but are generally inferior to any of the tested LISs at low temperature differences. To explain the observed non-linearity between LISs and the solid hydrophobic surface, we introduce two dominant regimes that influence the condensation efficiency: mobility-limited and coalescence-limited. Our findings advance the understanding of dynamic water-lubricant interactions and provide new design rationales for choosing surfaces for enhanced dropwise condensation and water collection efficiencies., submitted to Langmuir
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- 2021
19. Unimolecular Double Photoionization-Induced Processes in Iron Pentacarbonyl
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Roberto Linguerri, Emelie Olsson, Raimund Feifel, Gunnar Nyman, John H. D. Eland, and Majdi Hochlaf
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Range (particle radiation) ,Internal energy ,Chemistry ,Photoionization ,Photochemistry ,Article ,Iron pentacarbonyl ,Dication ,Catalysis ,Ion ,Inorganic Chemistry ,chemistry.chemical_compound ,Ionization ,Physical and Theoretical Chemistry - Abstract
The dissociations of nascent Fe(CO)5++ ions created by 40.81 eV photoionization of iron pentacarbonyl have been examined using threefold and fourfold electron–ion coincidence measurements. The energies and forms of the ions have been explored by high-level calculations, revealing several new structures. The most stable form of Fe(CO)5++ has a quite different geometry from that of the neutral molecule. The dissociation pattern can be modeled as a sequence of CO evaporations followed by two-body charge separations. Each Fe(CO)n++ (n = 1–4) dication is stable in a restricted energy range; as its internal energy increases, it first ejects a neutral CO, then loses CO+ by charge separation at higher energy. In the initial stages, charge-retaining CO evaporations dominate over charge separation, but the latter become more competitive as the number of residual CO ligands decreases. At energies where ionization is mainly from the CO ligands, new Fe–C and C–C bonds are created by a mechanism which might be relevant to catalysis by Fe., Dissociations of nascent Fe(CO)5++ ions by sequential CO evaporations, leading (in restricted energy ranges) to stable Fe(CO)n++ (n = 1−4) dicationic species. At energies where ionization is mainly from the CO ligands, new Fe−C and C−C bonds are created by a mechanism which might be relevant to catalysis by Fe.
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- 2021
20. Effects of Gas Adsorption Properties of an Au-Loaded Porous In2O3 Sensor on NO2-Sensing Properties
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Taro Ueda, Nicolae Barsan, Yasuhiro Shimizu, Takeo Hyodo, Udo Weimar, and Inci Boehme
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Fluid Flow and Transfer Processes ,Range (particle radiation) ,Materials science ,Diffuse reflectance infrared fourier transform ,Process Chemistry and Technology ,Analytical chemistry ,chemistry.chemical_element ,Bioengineering ,Oxygen ,Spectral line ,Adsorption ,chemistry ,Lattice oxygen ,Reactivity (chemistry) ,Porosity ,Instrumentation - Abstract
Gas adsorption properties of semiconductor-type gas sensors using porous (pr-) In2O3 powders loaded with and without 0.5 wt % Au (Au/pr-In2O3 and pr-In2O3 sensors, respectively) at 100 °C were examined by using diffuse reflectance infrared Fourier transform spectroscopy, and the effect of the Au loading onto pr-In2O3 on the NO2-sensing properties were discussed in this study. We found the following: the resistance of the Au/pr-In2O3 sensor in dry air is lower than that of the pr-In2O3 sensor; the DRIFT spectra of both the sensors show a broad positive band between 1600 and 1000 cm-1 in dry air (reference: in dry N2 at 100 °C), which mainly originates from oxygen adsorbates and/or lattice oxygen, and that this band is much larger for the Au/pr-In2O3 sensor than for the pr-In2O3 sensor; the Au loading also increases the adsorption amount of H2O and the reactivity of NO2 on the pr-In2O3 surface; and the NO2 response of the Au/pr-In2O3 sensor in dry air is marginally higher than that of the pr-In2O3 sensor in the examined concentration range of NO2 (0.6-5 ppm) in dry air. The obtained results strongly support the enhancement of the NO2 adsorption onto the pr-In2O3 surface by Au loading, which contributed to the improvement of the NO2-sensing properties.
- Published
- 2021
21. Comparing Isoelectronic, Quadruple-Bonded Metalloporphyrin and Metallocorrole Dimers: Scalar-Relativistic DFT Calculations Predict a >1 eV Range for Ionization Potential and Electron Affinity
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Hugo Vazquez-Lima, Jeanet Conradie, Abhik Ghosh, and Abraham B. Alemayehu
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Physics ,Range (particle radiation) ,Electron affinity ,Scalar (mathematics) ,General Medicine ,Ionization energy ,Molecular physics - Abstract
A scalar-relativistic DFT study of isoelectronic, quadruple-bonded Group 6 metalloporphyrins (M = Mo, W) and Group 7 metallocorroles (M = Tc, Re) has uncovered dramatic differences in ionization potential (IP) and electron affinity (EA) among the compounds. Thus, both the IPs and EAs of the corrole derivatives are 1 eV or more higher than those of the porphyrin derivatives. These differences largely reflect the much lower orbital energies of the δ- and δ*-orbitals of the corrole dimers relative to those of the porphyrin dimers, which in turn reflect the higher (+III as opposed to +II) oxidation states of the metals in the former compounds. Significant differences have also been determined between Mo and W porphyrin dimers and between Tc and Re corrole dimers. These differences are thought to largely reflect greater relativistic destabilization of the 5d orbitals of W and Re relative to the 4d orbitals of Mo and Tc. The calculated differences in IP and EA should translate to major differences in electrochemical redox potentials-a prediction that in our opinion is well worth confirming.
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- 2021
22. High-Pressure Synthesis of Bulk Cobalt Cementite, Co3C
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Scott D. Thiel, Paul V. Marshall, Yue Meng, James P. S. Walsh, Zeynep Alptekin, and Dean Smith
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Transition metal carbides ,Range (particle radiation) ,Materials science ,Cementite ,General Chemical Engineering ,Metallurgy ,chemistry.chemical_element ,General Chemistry ,Carbide ,chemistry.chemical_compound ,chemistry ,High pressure ,Heat shield ,Materials Chemistry ,Cobalt - Abstract
Transition metal carbides find use in a wide range of advanced high-resilience applications including high-strength steels, heat shields, and deep-earth drills. However, carbides of the mid-to-late...
- Published
- 2021
23. Tailored Design of Hierarchically Porous UiO-66 with a Controlled Pore Structure and Metal Sites
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Zhen Li, Shaokun Tang, and Xiaoyu Yang
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Metal ,Pore size ,Range (particle radiation) ,Materials science ,Chemical engineering ,visual_art ,visual_art.visual_art_medium ,General Materials Science ,General Chemistry ,Condensed Matter Physics ,Porosity - Abstract
Hierarchically porous metal–organic frameworks (MOFs) not only inherit the merits of MOFs such as high porosity, but they also possess distinct properties such as a broader pore size range and thus...
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- 2021
24. Metallic Hydrogen: A Liquid Superconductor?
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Jeffrey M. McMahon, Craig M. Tenney, and Zachary F. Croft
- Subjects
Superconductivity ,Work (thermodynamics) ,Range (particle radiation) ,Materials science ,Condensed matter physics ,Hydrogen ,Condensed Matter - Superconductivity ,FOS: Physical sciences ,chemistry.chemical_element ,Context (language use) ,Metallic hydrogen ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Superconductivity (cond-mat.supr-con) ,General Energy ,chemistry ,Condensed Matter::Superconductivity ,Phase (matter) ,Physical and Theoretical Chemistry ,Phase diagram - Abstract
Metallic hydrogen is expected to exhibit remarkable physics. Of particular interest in this work is the possibility of high-temperature superconductivity. Comparing calculations of the superconducting critical temperatures of the solid phase to melting temperatures over a range of pressures leads to an interesting question: Will the solid, in a superconducting state, melt to a liquid that remains a superconductor? In this work, the possibility of liquid superconductivity in metallic hydrogen is investigated. This is done by first-principles simulations, and using the results of these to solve the Eliashberg equations. These are carried out over the pressure (and temperature) conditions where molecular dissociation is expected to first occur in the solid phase. Over the pressure range $386.8(4)$--$783.7(4)$ GPa, $T_c$ increases from $308(6)$ to $372(2)$ K with a maximum uncertainty of $10$ K; it then decreases to $356(2)$ K at $883.7(3)$ GPa. Comparisons to the solid phase show that the critical temperature is not significantly changed between the two phases, though the physics behind their superconductivity is different. Careful comparisons of these values to recent results in the context of the hydrogen phase diagram show that they are higher than the melting temperatures and that the solid will melt to liquid atomic hydrogen. The results of this work (in this context) therefore suggest that liquid atomic hydrogen will indeed exist in a superconducting state. They also provide the pressure and temperature conditions over which to look for it.
- Published
- 2021
25. State-to-State Transition Study of the Exchange Reaction for N(4S) and O2(X3Σg−) Collision by Quasi-Classical Trajectory
- Author
-
Yan Wang and Xinlu Cheng
- Subjects
Vibration ,Range (particle radiation) ,Cross section (physics) ,Hypersonic speed ,Chemistry ,State (functional analysis) ,Rotational–vibrational spectroscopy ,Physical and Theoretical Chemistry ,Atomic physics ,Potential energy ,Excitation - Abstract
Based on the new 2A' and 4A' potential energy surfaces of NO2 fitted by Varga et al., we conducted a quasi-classical trajectory study on the N(4S) +O2(X3Σg- ) → NO(2Π) + O(3P) reaction, focusing on the high vibrational state up to ν = 25. For different rovibrational states of O2, within the relative translational energy (Ec) range of 0.1-30 eV, the total exchange cross section (ECS) is calculated, and it is found that the initial relative translational energy and vibration excitation have a significant effect on ECSs, while rotational excitation has little influence; the rate coefficient of the high rovibrational state of O2 molecules at high temperatures is studied, and it is found that when the vibrational level ν of O2 is in the range of 0-15, the value of log10k(T, ν, j) with the vibrational level ν is almost linear, while when ν is greater than 15, it becomes gentle with the increase in ν. Finally, the state-to-state rate coefficients are calculated; our results supply the advantageous state-to-state process data in the NO2 system, and they are useful for further studying the related hypersonic gas flow at very high temperature.
- Published
- 2021
26. Three-Dimensional Heterocycles by 5-exo-dig Cyclizations of S-Methyl-N-ynonylsulfoximines
- Author
-
Deshen Kong, Kari Rissanen, Ding Ma, Khai-Nghi Truong, Carsten Bolm, and Chenyang Wang
- Subjects
Range (particle radiation) ,Chemistry ,Dig ,Organic Chemistry ,Physical and Theoretical Chemistry ,Biochemistry ,Medicinal chemistry - Abstract
Upon treatment with Cs2CO3, S-methyl-N-ynonylsulfoximines undergo 5-exo-dig cyclizations to give three-dimensional heterocycles. The reactions proceed at ambient temperature with a wide range of substrates affording the corresponding products in good to excellent yields.
- Published
- 2021
27. Long-Range Electron Transfer through Ultrathin Polyelectrolyte Complex Films: A Hopping Model
- Author
-
Rachel L. Abbett, Joseph B. Schlenoff, Khalil Akkaoui, and Samir Abou Shaheen
- Subjects
Electron transfer ,Range (particle radiation) ,General Energy ,Materials science ,Chemical physics ,Physical and Theoretical Chemistry ,Polyelectrolyte ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials - Published
- 2021
28. Monitoring Ozone Using Portable Substrate-Integrated Hollow Waveguide-Based Absorbance Sensors in the Ultraviolet Range
- Author
-
Boris Mizaikoff, João Flávio da Silveira Petruci, Weida R. Silva, and Diandra Nunes Barreto
- Subjects
Range (particle radiation) ,QD71-142 ,Environmental Engineering ,Materials science ,Ozone ,business.industry ,Substrate (electronics) ,medicine.disease_cause ,Hollow waveguide ,Industrial and Manufacturing Engineering ,Absorbance ,chemistry.chemical_compound ,chemistry ,medicine ,Optoelectronics ,business ,Analytical chemistry ,Ultraviolet - Published
- 2021
29. Cr-Doped Fe1–xCrxF3·0.33H2O Nanomaterials as Cathode Materials for Sodium-Ion Batteries
- Author
-
Guixiao Jia, Xinping Qiu, Chao Zhang, He Zhao, Mingxia Yan, Wenting Li, Ce Han, Jie Li, and Shengli An
- Subjects
Range (particle radiation) ,Materials science ,Band gap ,law ,Doping ,Analytical chemistry ,Sodium-ion battery ,General Materials Science ,Titration ,Cathode ,Dielectric spectroscopy ,law.invention ,Nanomaterials - Abstract
Due to the high theoretical specific capacity and low cost, FeF3·0.33H2O has become one of the potential choices of cathode materials for sodium-ion batteries. However, the poor intrinsic conductivity limits its practical applications. Herein, the atomic substitution is used to improve its intrinsic conductivity. The first-principles calculation results show that Cr3+ doping can reduce the band gap of FeF3·0.33H2O to improve its intrinsic conductivity. The discharge specific capacity of Fe0.95Cr0.05F3·0.33H2O with a narrowest band gap is 194.02 mA h/g at 0.1 C within the range of 1.4-4.0 V, which is higher than that of FeF3·0.33H2O (136.47 mA h/g). Using the electrochemical impedance spectroscopy and galvanostatic intermittent titration technique tests, it is found that Rct of Fe0.95Cr0.05F3·0.33H2O is reduced and DNa+ is almost unchanged, as compared to FeF3·0.33H2O.
- Published
- 2021
30. Screening and Understanding Li Adsorption on Two-Dimensional Metallic Materials by Learning Physics and Physics-Simplified Learning
- Author
-
Sheng Gong, Taishan Zhu, Jeffrey C. Grossman, Zhenze Yang, Yang Shao-Horn, Shuo Wang, Markus J. Buehler, and Xi Chen
- Subjects
Coupling ,Physics ,Li adsorption ,Work (thermodynamics) ,Range (particle radiation) ,work function ,Substrate (electronics) ,2D materials ,high-throughput screening ,Article ,Chemistry ,Adsorption ,Chemical physics ,Density functional theory ,Work function ,physics-simplified learning ,Ionization energy ,QD1-999 - Abstract
Understanding and broad screening Li interaction energetics with surfaces are key to the development of materials for a wide range of applications including Li-based electrochemical capacitors, Li sensors, Li separation membranes, and Li-ion batteries. In this work, we build a high-throughput screening scheme to screen Li adsorption energetics on 2D metallic materials. First, density functional theory and graph convolution networks are utilized to calculate the minimum Li adsorption energies for some 2D metallic materials. The data is then used to find a dependence of the minimum Li adsorption energies on the sum of ionization potential, work function of the 2D metal, and coupling energy between Li+ and substrate, and the dependence is used to screen all 2D metallic materials. Physics-simplified learning by splitting the property into different contributions and learning or calculating each component is shown to have higher accuracy and transferability for machine learning of complex materials properties.
- Published
- 2021
31. Lowest Triplet and Singlet States in N-Methylacridone and N,N′-Dimethylquinacridone: Theory and Experiment
- Author
-
Bernd Kosper, Rainer Weinkauf, Jan Meissner, and Christel M. Marian
- Subjects
Range (particle radiation) ,Chemistry ,Excited state ,Multireference configuration interaction ,Molecule ,Density functional theory ,Singlet state ,Physics::Chemical Physics ,Physical and Theoretical Chemistry ,Atomic physics ,Spectral line ,Ion - Abstract
In this work, radical anion photodetachment photoelectron (PD-PE) spectra of N-methylacridone (NM-AC) and N,N'-dimethyl-trans-quinacridone (NNM-QAC) are presented, from which we derived electron affinities and transition energies from S0 to the lowest excited triplet and singlet states (T1, T2, and S1). Because in molecules with extended π systems and heteroatoms the state density even in the energy range of the lowest excited electronic states is already high, assignment of most of the spectral structures in the PD-PE spectra was possible only on the basis of theoretical calculations. To this end, adiabatic transition energies including zero-point vibrational energy corrections were determined using a combination of density functional theory, time-dependent density functional theory, and multireference configuration interaction methods. Calculated Franck-Condon spectra proved to be particularly valuable for the assignment of the spectra. Surprisingly, the density of electronically excited states in the low-energy regime is smaller for NNM-QAC than for NM-AC. This is due to the fact that the nπ* energies remain nearly the same in the two molecules whereas the lowest ππ* excited singlet and triplet transitions are strongly red-shifted in going from NM-AC to NNM-QAC.
- Published
- 2021
32. Pressure Effects on the Relaxation of an Excited Ethane Molecule in High-Pressure Bath Gases
- Author
-
Luis A. Rivera-Rivera, Chad R. Lazarock, Albert F. Wagner, Tasha A. Vincent, and Zackary R. Hren
- Subjects
Molecular dynamics ,Range (particle radiation) ,Chemistry ,Excited state ,Vibrational energy relaxation ,Relaxation (physics) ,Noble gas ,Molecule ,Physical and Theoretical Chemistry ,Bond-dissociation energy ,Molecular physics - Abstract
We use molecular dynamics to calculate the rotational and vibrational energy relaxation of C2H6 in Ar, Kr, and Xe bath gases over a pressure range of 10-400 atm and at temperatures of 300 and 800 K. The C2H6 is instantaneously excited by 80 kcal/mol randomly distributed into both vibrational and rotational modes. The computed relaxation rates show little sensitivity to the identity of the noble gas in the bath. Vibrational relaxation rates show a nonlinear pressure dependence at 300 K. At 800 K the reduced range of bath gas densities covered by the range of pressures does not yet show any nonlinearity in the pressure dependence. Rotational relaxation is characterized with two relaxation rates. The slower rate is comparable to the vibrational relaxation rate. The faster rate has a linear pressure dependence at 300 K but an irregular, nonlinear pressure dependence at 800 K. To understand this, a model was developed based on approximating the periodic box used in the molecular dynamics simulations by an equal-volume collection of cubes where each cube is sized to allow only single occupancy by the noble gas or the molecule. Combinatorial statistics then leads to a pressure- and temperature-dependent analytic distribution of the bath gas species the molecule encounters in a collision. This distribution, the dissociation energy of molecule/bath gas complexes and bath gas clusters, and the computed energy release per collision combine to show that only at 300 K is the energy release sufficient to dissociate likely complexes and clusters. This suggests that persistent and pressure-dependent clusters and complexes at 800 K may be responsible for the nonlinear pressure dependence of rotational relaxation.
- Published
- 2021
33. Solvent Processing and Ionic Liquid-Enabled Long-Range Vertical Ordering in Block Copolymer Films with Enhanced Film Stability
- Author
-
Maninderjeet Singh, Ali Ammar, Joseph Strzalka, Jack F. Douglas, Ali Masud, Kshitij Sharma, Wafa Tonny, Tanguy Terlier, Wenjie Wu, and Alamgir Karim
- Subjects
Range (particle radiation) ,Materials science ,Polymers and Plastics ,Organic Chemistry ,Processing methods ,Inorganic Chemistry ,Solvent ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Ionic liquid ,Materials Chemistry ,Copolymer ,Thin film - Abstract
Rapid and reliable processing methods for forming ordered block copolymer (BCP) materials with low defect density in a thin film geometry are required for many nanotechnology applications. Vertical...
- Published
- 2021
34. Electrochemical Oxidative Difunctionalization of Alkenes to Access α-Oxygenated Ketones
- Author
-
Yijie Shen, Ping Liu, Changhui Dai, Peipei Sun, and Yifan Wei
- Subjects
Range (particle radiation) ,Transition metal ,Chemistry ,Organic Chemistry ,chemistry.chemical_element ,Oxidative phosphorylation ,Electrochemistry ,Photochemistry ,Oxygen - Abstract
Dioxygenation of alkenes was developed by the combination of electrochemical synthesis and aerobic oxidation, leading to easy accessibility of α-oxygenated ketones in an eco-friendly fashion. Using air as the oxygen source and the absence of transition metals were the critical features of this protocol. A wide range of alkenes and N-hydroxyimides were found to be compatible and provided α-oxygenated ketones in moderate to high yields.
- Published
- 2021
35. Spray Atomization and Links to Flame Stability over a Range of Weber Numbers and Pressure Ratios
- Author
-
K. Jayanandan, Agisilaos Kourmatzis, G. Singh, and Assaad R. Masri
- Subjects
Range (particle radiation) ,Fuel Technology ,Materials science ,General Chemical Engineering ,Analytical chemistry ,Energy Engineering and Power Technology ,Spray atomization ,Stability (probability) - Published
- 2021
36. Probing the Water Uptake and Phase State of Individual Sucrose Nanoparticles Using Atomic Force Microscopy
- Author
-
Hansol D. Lee, Chamika K. Madawala, Alexei V. Tivanski, and Chathuri P. Kaluarachchi
- Subjects
Atmospheric Science ,Phase transition ,Range (particle radiation) ,Letter ,atomic force microscopy ,Morphology (linguistics) ,Materials science ,aerosol particles ,Nanoparticle ,Substrate (chemistry) ,phase state ,sucrose ,relative humidity ,Atmosphere ,Chemical engineering ,Space and Planetary Science ,Geochemistry and Petrology ,Phase (matter) ,nanoparticles ,Relative humidity - Abstract
The effects of atmospheric aerosols on the climate and atmosphere of Earth can vary significantly depending upon their properties, including size, morphology, and phase state, all of which are influenced by varying relative humidity (RH) in the atmosphere. A significant fraction of atmospheric aerosols is below 100 nm in size. However, as a result of size limitations of conventional experimental techniques, how the particle-to-particle variability of the phase state of aerosols influences atmospheric processes is poorly understood. To address this issue, the atomic force microscopy (AFM) methodology that was previously established for sub-micrometer aerosols is extended to measure the water uptake and identify the phase state of individual sucrose nanoparticles. Quantified growth factors (GFs) of individual sucrose nanoparticles up to 60% RH were lower than expected values observed on the sub-micrometer sucrose particles. The effect could be attributed to the semisolid sucrose nanoparticle restructuring on a substrate. At RH > 60%, sucrose nanoparticles are liquid and GFs overlap well with the sub-micrometer particles and theoretical predictions. This suggests that quantification of GFs of nanoparticles may be inaccurate for the RH range where particles are semisolid but becomes accurate at elevated RH where particles are liquid. Despite this, however, the identified phase states of the nanoparticles were comparable to their sub-micrometer counterparts. The identified phase transitions between solid and semisolid and between semisolid and liquid for sucrose were at ∼18 and 60% RH, which are equivalent to viscosities of 1011.2 and 102.5 Pa s, respectively. This work demonstrates that measurements of the phase state using AFM are applicable to nanosized particles, even when the substrate alters the shape of semisolid nanoparticles and alters the GF.
- Published
- 2021
37. Electronic g-Tensor Calculations for Dangling Bonds in Nanodiamonds
- Author
-
Zilvinas Rinkevicius, Šaru Nas Masys, Valdas Jonauskas, and American Chemical Society
- Subjects
Range (particle radiation) ,Chemistry ,Chemical physics ,molecular-orbital methods ,Dangling bond ,Tensor ,Physical and Theoretical Chemistry ,Total energy ,effective nuclear charges ,surface modification - Abstract
The electronic g-tensor calculations are performed for dangling bonds (DBs) introduced into nanodiamonds (NDs) with four different functional groups on their surfaces. For hydrogenated and fluorinated NDs, it is found that g-shifts of the latter vary in a much wider range, and the same is also true for the total energy differences between the highest and the lowest energy DBs. In addition, it is shown that the shape of NDs significantly impacts the energetics and g-shifts of DBs, whereas the influence of the size is much less pronounced, as is the influence of the presence of one DB in the vicinity of the other, resulting in no substantial change on their magnetic behavior. For hydroxylated and aminated NDs, it is demonstrated that the variation range of g-shifts is larger for the former, whereas the opposite is seen regarding the total energy differences. On the whole, some of the positions of DBs can be energetically very costly in these NDs; besides, the lowest energy DBs are irregular, that is, formed by OH- and NH2-bonded C atoms, contrasting with hydrogenated and fluorinated NDs, for which irregular DBs are the most energetically unfavorable.
- Published
- 2021
38. Organic Ternary Bulk Heterojunction Broadband Photodetectors Based on Nonfullerene Acceptors with a Spectral Response Range from 200 to 1050 nm
- Author
-
Dayong Jiang, Man Zhao, and Siyuan Weng
- Subjects
chemistry.chemical_classification ,Range (particle radiation) ,Materials science ,business.industry ,Photodetector ,Electron donor ,Electron acceptor ,Polymer solar cell ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,General Energy ,chemistry ,Broadband ,Optoelectronics ,Physical and Theoretical Chemistry ,business ,Absorption (electromagnetic radiation) ,Ternary operation - Abstract
Compared with the electron donor of the bulk heterojunction (BHJ) organic/inorganic photodetectors (OPDs), there is less development in the field of electron acceptors that have strong absorption c...
- Published
- 2021
39. Advanced Configuration of N-Enriched Carbonized Tissue Paper as a Free-Standing Interlayer for Lithium–Sulfur Batteries at Wide-Range Temperatures
- Author
-
Qinggang He, Xiang Gao, Azim Uddin, Haichao Tang, Rabia Khatoon, Jianguo Lu, Zhou Peng Li, Yichuan Guo, Yang Tian, Sanam Attique, Nasir Ali, and Zhizhen Ye
- Subjects
Range (particle radiation) ,Materials science ,Carbonization ,Materials Chemistry ,Electrochemistry ,Analytical chemistry ,Energy Engineering and Power Technology ,Chemical Engineering (miscellaneous) ,Lithium sulfur ,Electrical and Electronic Engineering ,Tissue paper - Published
- 2021
40. Kinetic and Dynamic Studies of the F(2P) + ND3 → DF + ND2 Reaction
- Author
-
Hongwei Song, Li Tian, Yong Li, Haipan Xiang, and Rong Xin
- Subjects
Range (particle radiation) ,Chemistry ,Thermal ,Kinetic isotope effect ,Potential energy surface ,Inverse ,Thermodynamics ,Substitution effect ,Physical and Theoretical Chemistry ,Kinetic energy ,Ground state - Abstract
The fast F reaction with NH3 poses a big challenge to experimental studies because of secondary chemical and collisional reactions. The quasi-classical trajectory method is utilized to investigate the mode specificity, product energy disposal, and temperature dependence of the thermal rate coefficient of F + ND3 → DF + ND2 on a recently developed potential energy surface. The effect of isotopic substitution is explored by comparing the F + ND3 reaction with the F + NH3 reaction. The computed results permit a better understanding of the F + ammonia reaction. The DF vibrational state has a Λ-type distribution, in accordance with the experimental measurement by the fast flow reactor technique. The product ND2 is dominantly populated in the ground state, and a considerable amount of ND2 is produced in the fundamental states of the bending mode. The similar vibrational state distributions of HF and NH2 in the F + NH3 reaction indicate a weak isotopic substitution effect on the product energy disposal. Exciting the umbrella mode of ND3 suppresses the reaction at low energies below 5 kcal mol-1, in sharp contrast to the observation in the F + NH3 reaction. These dynamical behaviors can be partially explained by the sudden vector projection model. In addition, the thermal rate coefficient of F + ND3 shows no temperature dependence in the range between 150 and 2000 K. There exists an inverse kinetic isotope effect at temperatures from 150 to 1500 K.
- Published
- 2021
41. Ab Initio Study of CO2 Activation on Pristine and Fe-Decorated WS2 Nanoflakes
- Author
-
Lucas G. Verga, Juarez L. F. Da Silva, and Henrique Alves Bacco Fonseca
- Subjects
Work (thermodynamics) ,Crystallography ,Range (particle radiation) ,Adsorption ,Physisorption ,Chemistry ,Ab initio ,Density functional theory ,Physical and Theoretical Chemistry ,Catalysis - Abstract
There is an intense race by the scientific community to identify materials with potential applications for the conversion of carbon dioxide (CO2) into new products. To extend the range of possibilities and explore new effects, in this work, we employ density functional theory calculations to investigate the presence of edge effects in the adsorption and activation of CO2 on pristine and Fe-decorated (WS2)16 nanoflakes. We found that Fe has an energetic preference for hollow sites on pristine nanoflakes, binding with at least two two-fold edge S atoms and one or two three-fold core S atoms. Fe adsorption on the bridge sites occurs only at the edges, which is accompanied by the breaking of W-S bonds in most cases (higher energy configurations). CO2 activates on (WS2)16 with an OCO angle of about 129° only at higher energy configurations, while CO2 binds via a physisorption mechanism, linear structure, in the lowest energy configuration. For CO2 on Fe/(WS2)16, the activation occurs at lower energies only by the direct interaction of CO2 with Fe sites located near to the nanoflake edges, which clearly indicates the enhancement of the catalytic activity of (WS2)16 nanoflakes by Fe decoration. Thus, our study indicates that decorating WS2 nanoflakes with TM atoms could be an interesting strategy to explore alternative catalysts based on two-dimensional materials.
- Published
- 2021
42. Experimental Study on Droplet Splash and Receding Breakup on a Smooth Surface at Atmospheric Pressure
- Author
-
Lei Yang, Yicheng Chi, Tao Yang, Zhonghong Li, and Peng Zhang
- Subjects
Splash ,Range (particle radiation) ,Materials science ,Atmospheric pressure ,Surfaces and Interfaces ,Mechanics ,Condensed Matter Physics ,Breakup ,Ohnesorge number ,Smooth surface ,Liquid film ,Electrochemistry ,Weber number ,General Materials Science ,Spectroscopy - Abstract
Droplet impact on a smooth solid surface at atmospheric pressure was experimentally studied and physically interpreted. A particular emphasis of the study is on the effects of liquid viscosity on the transition between droplet deposition (or droplet spreading without breakup) and droplet disintegration (including droplet splash and receding breakup). Specifically, the critical Weber number separating droplet deposition from droplet disintegration decreases and then increases with increasing Ohnesorge number (Oh). The splash in the low-Oh region and the receding breakup in the high-Oh region were analyzed qualitatively based on the unbalanced forces acting on the rim of the spreading or receding liquid film. A semiempirical correlation of droplet deposition/disintegration thresholds is proposed and well fits the experimental results from previous and present studies over a wide range of liquid viscosity.
- Published
- 2021
43. Influence of Calendering on the Electrochemical Performance of LiNi0.9Mn0.05Al0.05O2 Cathodes in Lithium-Ion Cells
- Author
-
Wangda Li, Richard Sim, Steven Lee, and Arumugam Manthiram
- Subjects
Range (particle radiation) ,Materials science ,chemistry.chemical_element ,Electrochemistry ,Cathode ,law.invention ,Calendering ,chemistry ,law ,Electrode ,Particle ,General Materials Science ,Lithium ,Composite material ,Fade - Abstract
Electrode calendering is a necessary process used in industry to improve the volumetric capacity of lithium-ion batteries. However, calendering high-nickel cathodes leads to electrode particle pulverization, raising concerns of a reduced cycle life due to parasitic side reactions. We present here an investigation of the impact of calendering on the morphology and electrochemical performance of the cobalt-free layered oxide cathode LiNi0.9Mn0.05Al0.05O2 (NMA-90). We find that secondary particle pulverization and fusion simultaneously occur at sufficiently high pressures. The initial surface area of the cathode is shown to increase with the degree of calendering, despite the higher likelihood of secondary particle fusion. Long-term cycling of full coin cells assembled with the NMA-90 cathode and the graphite anode indicates that cells with higher degrees of cathode calendering exhibit lower capacity fade compared to uncalendered cathodes. Hybrid pulse-power tests demonstrate that the usable capacity range of cells with calendered cathodes far exceeds those with uncalendered cells after long-term cycling. The improved capacity retention and pulse-power performance are attributed to the enhanced mechanical properties of the electrode after calendering that prevents loss of the primary particle contact during long-term cycling. We find that calendering high-nickel NMA-90 to industrially relevant densities does not have a detrimental effect on capacity fade, marking an important step toward commercial adoption.
- Published
- 2021
44. Drop Bouncing Dynamics on Ultrathin Films
- Author
-
Ziwen He, Huy Tran, and Min Pack
- Subjects
Entrainment (hydrodynamics) ,Range (particle radiation) ,Momentum (technical analysis) ,Materials science ,Drop (liquid) ,Surfaces and Interfaces ,Substrate (electronics) ,Condensed Matter Physics ,Lift (force) ,Electrochemistry ,General Materials Science ,Thin film ,Composite material ,Layer (electronics) ,Spectroscopy - Abstract
For drops to contact various surfaces, the removal of the interstitial fluid is the prerequisite to contact. While the conventional understanding is for drops to irreversibly spread on a film made of the same substance, we describe the dynamics of drops initiating contact yet carrying enough momentum to completely lift off of the substrate which we label as contact bouncing. We report new experimental results of the dynamics between drops impacting thin films described by the ratio of the liquid film hL to the drop with diameter D0 for the range of 0.004 < hL/D0 < 0.08. Using high-speed interferometry, we visualize the interfacial gas layer spatiotemporal signatures across the various film thicknesses and Weber numbers. We find that while increasing the deformability of the thin films enhances the gas entrainment phenomenon at early times, it also increases the rate of the gas purging rate, increasing the chance of contact just prior to the gas film retraction and drop lift off sequence. Drops which contact the liquid film during the retraction stage are able to bounce with
- Published
- 2021
45. Multiplexing of Electrospray Ionization Sources Using Orthogonal Injection into an Electrodynamic Ion Funnel
- Author
-
Xi Chen, Hugo Y. Samayoa Oviedo, Habib Gholipour-Ranjbar, Andrew J. Smith, Pei Su, Carlos Larriba-Andaluz, Solita M. Wilson, Michael Forrester Espenship, and Julia Laskin
- Subjects
Ions ,Spectrometry, Mass, Electrospray Ionization ,Range (particle radiation) ,business.product_category ,Field (physics) ,Chemistry ,Electrospray ionization ,Analytical chemistry ,Ion current ,Mass spectrometry ,Multiplexing ,Injections ,Analytical Chemistry ,Ion ,Funnel ,business - Abstract
In this contribution, we report an efficient approach to multiplex electrospray ionization (ESI) sources for applications in analytical and preparative mass spectrometry. This is achieved using up to four orthogonal injection inlets implemented on the opposite sides of an electrodynamic ion funnel interface. We demonstrate that both the total ion current transmitted through the mass spectrometer and the signal-to-noise ratio increase by 3.8-fold using four inlets compared to one inlet. The performance of the new multiplexing approach was examined using different classes of analytes covering a broad range of mass and ionic charge. A deposition rate of >10 μg of mass-selected ions per day may be achieved by using the multiplexed sources coupled to preparative mass spectrometry. The almost proportional increase in the ion current with the number of ESI inlets observed experimentally is confirmed using gas flow and ion trajectory simulations. The simulations demonstrate a pronounced effect of gas dynamics on the ion trajectories in the ion funnel, indicating that the efficiency of multiplexing strongly depends on gas velocity field. The study presented herein opens up exciting opportunities for the development of bright ion sources, which will advance both analytical and preparative mass spectrometry applications.
- Published
- 2021
46. Extended Compositional Range for the Synthesis of SWIR and LWIR Ge1–ySny Alloys and Device Structures via CVD of SnH4 and Ge3H8
- Author
-
Dhruve A. Ringwala, Jose Menendez, John Kouvetakis, Matthew A. Mircovich, Chi Xu, and Christian D. Poweleit
- Subjects
Range (particle radiation) ,Materials science ,business.industry ,Materials Chemistry ,Electrochemistry ,Optoelectronics ,business ,Electronic, Optical and Magnetic Materials - Published
- 2021
47. Efficient, Stable, and Photoluminescence Intermittency-Free CdSe-Based Quantum Dots in the Full-Color Range
- Author
-
Liantuan Xiao, Wenli Guo, Ruilin Xiao, Bin Li, Sirong Zhou, Chengbing Qin, Danhong Wang, Xue Han, Liheng Feng, Suotang Jia, Jianyong Hu, Jialu Li, Yonggang Yang, Xiuqing Bai, Changgang Yang, Guofeng Zhang, and Ruiyun Chen
- Subjects
Range (particle radiation) ,Photoluminescence ,Materials science ,business.industry ,Full color ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,law.invention ,Quantum dot ,law ,Intermittency ,Optoelectronics ,Electrical and Electronic Engineering ,business ,Biotechnology - Published
- 2021
48. Thermal Decomposition of CH3O: A Curious Case of Pressure-Dependent Tunneling Effects
- Author
-
Thanh Lam Nguyen, Peter R. Franke, John F. Stanton, and A. R. Ravishankara
- Subjects
Range (particle radiation) ,chemistry.chemical_compound ,chemistry ,Master equation ,Thermal ,Kinetic isotope effect ,Thermal decomposition ,Thermodynamics ,Physics::Chemical Physics ,Physical and Theoretical Chemistry ,Combustion ,Quantum tunnelling ,Methane - Abstract
The thermal unimolecular decomposition of a methoxy radical (CH3O), a key intermediate in the combustion of methane, methanol, and other hydrocarbons, was studied using high-level coupled-cluster calculations, followed by E,J-resolved master equation analyses. The experimental results available for a wide range of temperature and pressure are in striking agreement with the calculations. In line with a previous theoretical study that used a one-dimensional master equation, the tunneling correction is found to exhibit a marked pressure dependence, being the largest at low pressure. This curious effect on the tunneling enhancement also affects the calculated kinetic isotope effect, which falls initially with pressure but is predicted to rise again at high pressures. These findings serve to reconcile a set of conflicting results regarding the importance of tunneling in this prototype unimolecular reaction and also motivate further experimental investigation. This study also exemplifies how changes in the energy redistribution due to collisions manifest in the tunneling rates.
- Published
- 2021
49. Moiré Skyrmions and Chiral Magnetic Phases in Twisted CrX3 (X = I, Br, and Cl) Bilayers
- Author
-
Dibyendu Dey, Muhammad Akram, Onur Erten, Antia S. Botana, Jesse Kapeghian, and Harrison LaBollita
- Subjects
Condensed Matter - Materials Science ,Range (particle radiation) ,Materials science ,Condensed matter physics ,Field (physics) ,Mechanical Engineering ,Bilayer ,Skyrmion ,Bioengineering ,General Chemistry ,Condensed Matter Physics ,Crystal ,Condensed Matter - Strongly Correlated Electrons ,Ferromagnetism ,Antiferromagnetism ,Condensed Matter::Strongly Correlated Electrons ,General Materials Science ,Twist - Abstract
We present a comprehensive theory of the magnetic phases in twisted bilayer chromium trihalides through a combination of first-principles calculations and atomistic simulations. We show that the stacking-dependent interlayer exchange leads to an effective moire field that is mostly ferromagnetic with antiferromagnetic patches. A wide range of noncollinear magnetic phases can be stabilized as a function of the twist angle and Dzyaloshinskii-Moriya interaction as a result of the competing interlayer antiferromagnetic coupling and the energy cost for forming domain walls. In particular, we demonstrate that for small twist angles various skyrmion crystal phases can be stabilized in both CrI3 and CrBr3. Our results provide an interpretation for the recent observation of noncollinear magnetic phases in twisted bilayer CrI3 and demonstrate the possibility of engineering further nontrivial magnetic ground states in twisted bilayer chromium trihalides.
- Published
- 2021
50. Influence of the Hollowness and Size Distribution on the Magnetic Properties of Fe3O4 Nanospheres
- Author
-
Qingnan Meng, Jun Yang, Yang Shi, and Zhenhua Han
- Subjects
Diffraction ,Range (particle radiation) ,Materials science ,Magnetometer ,Surfaces and Interfaces ,Coercivity ,Condensed Matter Physics ,law.invention ,Chemical engineering ,law ,Transmission electron microscopy ,Electrochemistry ,General Materials Science ,High saturation magnetization ,Spectroscopy ,Thermal methods - Abstract
In this study, Fe3O4 nanospheres with different levels of hollowness were successfully prepared by the solvent thermal method. The synthesized Fe3O4 nanospheres were characterized by transmission electron microscopy, X-ray diffraction, and vibrating sample magnetometry, and Image-Pro software was used to analyze the hollowness of the Fe3O4 nanospheres for the first time. It was found that excess reactants could lead to the disappearance of the hollow structure of the Fe3O4 nanospheres, and the reason for this phenomenon was discussed as due to entropy increase theory. Furthermore, the influence of the hollowness and size distribution on the magnetic properties of the Fe3O4 nanospheres was evaluated. The magnetic properties of a Fe3O4 nanosphere with a hollowness of 10.48% showed a relatively high saturation magnetization of 103 emu/g and a rather low coercivity (54 Oe). The as-prepared Fe3O4 nanospheres are expected to be useful in a wide range of fields such as drug-delivery and energy applications.
- Published
- 2021
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