Structural Basis of Nav1.7 Inhibition by a Gating-Modifier Spider Toxin
Abstract not provided
Xu, Hui↗
Engineering topics
Chen, Jun
Publications and source records attributed to Chen, Jun.
Multiple contributions to electrostrain in high performance PbTiO 3 –Bi(Ni 1/2 Hf 1/2 )O 3 piezoceramics triggered by phase transformation
Piezoelectric materials, which mechanically respond to electrical stimulation and vice versa, typically exhibit high piezoelectricity at a morphotropic phase boundary (MPB). A thorough structural description is essential for understanding the origin of excellent piezoelectric properties. In this work, a comparative study of electric-field-driven structure and phase evolution has been conducted on MPB and non-MPB tetragonal composition in high performance system of PbTiO 3 -Bi(Ni 1/2 Hf 1/2 )O 3 piezoceramics using in situ high-energy synchrotron X-ray diffraction. The results show that the MPB composition exhibits electric-field-driven reversible tetragonal-to-monoclinic transformation, whereas non-MPB composition does not. Direct evidence shows that the extensive phase transformation triggers multiple contributions to enhancing piezoelectric performance. Namely, it not only enables the unit cell parameters of coexisting phases easily change with an external electric field, but also enhances the domain switching and lattice strain. These results offer a unique perspective on MPB associated piezoelectricity enhancement, and will be helpful for developing high performance piezoelectric materials.
36 MATERIALS SCIENCE↗
Few-Layer Graphene Functionalized by Carbon Nanotubes and MnO{sub 2} Nanoparticles for High-Performance Supercapacitors
Few-layer graphene (FLG) exfoliated from graphite is an attractive electrode material due to its high conductivity and high chemical stability. But usually limited by their specific surface area (SSA), its capacitance needs to be improved when used in supercapacitors. In this study, FLG has been prepared by combining electrochemical exfoliation and thermal expansion. It has a SSA of 148 m{sup 2}/g and delivers a capacitance of 55 F/g at a discharge current density of 1 A/g. To increase its capacitance, carbon nanotubes (CNTs) and MnO{sub 2} nanoparticles are functionalized onto FLG surface separately. Both modification could achieve a composite electrode with enhanced capacitance. The CNT/FLG and MnO{sub 2}/FLG electrodes show a specific capacitance of 106 and 336 F/g at the current density of 1 A/g, respectively, while the former exhibits a much better rate performance and cycling stability than the latter. This work demonstrates an optional way to improve the performance of FLG-based supercapacitors.
36 MATERIALS SCIENCE↗
Robust triboelectric nanogenerator based on rolling electrification
A generator for converting mechanical energy or hydropower or wind energy into electrical energy is disclosed. The generator includes a first member and a second member in contact with the first member to generate triboelectric charges. The second member rolls against the first member to generate a flow of electrons between two electrodes. Another embodiment of the generator includes two electrodes, and a member in contact with the two electrodes to generate triboelectric charges. The member rolls against the electrodes to generate a flow of electrons between the two electrodes.
Wang, Zhong Lin↗
Nuclear Data Sheets for A=50
The experimental nuclear structure and decay data are evaluated for all the known nuclides of mass 50 (Cl, Ar, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni). Here, detailed evaluated nuclear structure information are presented in individual decay and reaction datasets and the best values are recommended in the Adopted dataset for level properties, γ and β radiations, and other spectroscopic information. No excited states are known in 50Cl and 50Ni, and limited information is available for 50 Ar, 50 K, 50 Fe and 50 Co. This work supersedes earlier evaluations of A=50 by 2011El01, 1995Bu09, 1990Bu18, 1984Al29, and 1976Au07.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Enhanced tetragonality and large negative thermal expansion in a new Pb/Bi-based perovskite ferroelectric of (1 – x )PbTiO 3 – x Bi(Zn 1/2 V 1/2 )O 3
The investigation of a large negative thermal expansion (NTE) over a wide temperature range has been a vital subject in materials science, since the overall coefficient of thermal expansion (CTE) of ordinary materials can be effectively tailored by the introduction of NTE materials. Here, we successfully achieved a large NTE within a broad temperature range in a new Pb/Bi-based ferroelectric of (1 – x)PbTiO 3 –xBi(Zn 1/2 V 1/2 )O 3 by means of improving the ferroelectricity of PbTiO 3 . The current system exhibits an unusual enhanced tetragonality, large spontaneous polarization (P S ), and high Curie temperature (T C ). Specifically, the x = 0.1 compound exhibits an enhanced CTE of –2.10 × 10 –5 °C –1 from room temperature (RT) up to its T C of 600 °C, which is in contrast to that of pristine PbTiO 3 (–1.99 × 10 –5 °C –1 , RT–490 °C). More intriguingly, a large volume shrinkage (ΔV ≈ –1%) has also been observed during the ferroelectric-to-paraelectric phase transition. According to experimental and theoretical studies, the large NTE is attributed to the enhanced P S derived from the strong hybridization of Pb/Bi–O and Ti/Zn/V–O through the substitution of the polar Bi(Zn 1/2 V 1/2 )O 3 perovskite. The present study demonstrates that a large NTE within a wide temperature range can be achieved in PbTiO 3 -based ferroelectrics by improving its ferroelectricity through introducing isostructural polar perovskites.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Ultrathin, flexible, solid polymer composite electrolyte enabled with aligned nanoporous host for lithium batteries
The urgent need for safer batteries is leading research to all-solid-state lithium-based cells. To achieve energy density comparable to liquid electrolyte-based cells, ultrathin and lightweight solid electrolytes with high ionic conductivity are desired. However, solid electrolytes with comparable thicknesses to commercial polymer electrolyte separators (~10 μm) used in liquid electrolytes remain challenging to make because of the increased risk of short-circuiting the battery. In this work, we report on a polymer–polymer solid-state electrolyte design, demonstrated with an 8.6-μm-thick nanoporous polyimide (PI) film filled with polyethylene oxide/lithium bis(trifluoromethanesulfonyl)imide (PEO/LiTFSI) that can be used as a safe solid polymer electrolyte. The PI film is nonflammable and mechanically strong, preventing batteries from short-circuiting even after more than 1,000 h of cycling, and the vertical channels enhance the ionic conductivity (2.3 × 10 -4 S cm -1 at 30 °C) of the infused polymer electrolyte. Lastly, all-solid-state lithium-ion batteries fabricated with PI/PEO/LiTFSI solid electrolyte show good cycling performance (200 cycles at C/2 rate) at 60 °C and withstand abuse tests such as bending, cutting and nail penetration.
25 ENERGY STORAGE↗
Nuclear Data Sheets for A=73☆
Experimental nuclear structure data for the known A=73 isobaric nuclides (Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Br, Kr, Rb and Sr) have been evaluated, and presented together with Adopted properties of level energies, and associated γ rays. The decay data for these nuclides have also been evaluated, providing Adopted values of γ and β radiations, and log ft values. For {sup 73}Mn, only the isotopic identification has been established, with no knowledge of its g.s. half-life. For {sup 73}Fe, {sup 73}Co and {sup 73}Sr, only the ground states and their half-lives are known with no information about the excited states. For {sup 73}Ni, {sup 73}Cu, {sup 73}Zn and {sup 73}Rb, little data are available for excited states. The half-life and decay modes of possibly proton-unbound {sup 73}Rb need firmly established. {sup 73}Ga structure presents a special challenge in that the 1/2{sup −} ground state and the first 3/2{sup −} state have recently been proposed, in a Coulomb excitation experiment by 2010Di14, to form an almost degenerate doublet with an estimated spacing of 229 Th with its first excited state at 7.8 eV, and {sup 235}U with its first excited state at 76 eV. Ultra-high resolution gamma-ray spectroscopic studies are warranted to search for the low-lying (73 Ga, and to determine its half-life. Level structures of {sup 73}Ga, {sup 73}Ge, {sup 73}As, {sup 73}Se, {sup 73}Br and {sup 73}Kr are quite well known, although decay schemes of radioactive ground states of {sup 73}Co, {sup 73}Cu and {sup 73}Br are considered incomplete. The reactions and decays for which no new experimental information has become available since the 2003 update have undergone revisions to incorporate conversion coefficients from BrIcc code, and evaluated Q values from 2017Wa10, but essential content of such datasets may have remained the same as in previous evaluations. In this respect the present work greatly benefited from all the previous NDS evaluations (2004Si08,1993Ki25,1987Ki13, 1980Ek01,1974Al33), but at the same time data presented herein supersede all the previous published evaluations.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Quasi-separatrix layers induced by ballooning instability in the near-Earth magnetotail
Magnetic reconnection processes in the near-Earth magnetotail can be highly three-dimensional (3-D) in geometry and dynamics, even though the magnetotail configuration itself is nearly two-dimensional due to the symmetry in the dusk–dawn direction. Such reconnection processes can be induced by the 3-D dynamics of nonlinear ballooning instability. In this work, we explore the global 3-D geometry of the reconnection process induced by ballooning instability in the near-Earth magnetotail by examining the distribution of quasi-separatrix layers associated with plasmoid formation in the entire 3-D domain of magnetotail configuration, using an algorithm previously developed in the context of solar physics. The 3-D distribution of quasi-separatrix layers (QSLs) as well as their evolution directly follow the plasmoid formation during the nonlinear development of ballooning instability in both time and space. Such a close correlation demonstrates a strong coupling between the ballooning and the corresponding reconnection processes. It further confirms the intrinsic 3-D nature of the ballooning-induced plasmoid formation and reconnection processes, in both geometry and dynamics. In addition, the reconstruction of the 3-D QSL geometry may provide an alternative means of identifying the location and timing of 3-D reconnection sites in the magnetotail from both numerical simulations and satellite observations.
79 ASTRONOMY AND ASTROPHYSICS↗
Negative Thermal Expansion in (Hf,Ti)Fe 2 Induced by the Ferromagnetic and Antiferromagnetic Phase Coexistence
Negative thermal expansion (NTE) is an intriguing physical phenomenon that can be used in the applications of thermal expansion adjustment of materials. In this study, we report a NTE compound of (Hf,Ti)Fe 2 , while both end members of HfFe 2 and TiFe 2 show positive thermal expansion. The results reveal that phase coexistence is detected in the whole NTE zone, in which one phase is ferromagnetic (FM), while the other is antiferromagnetic (AFM). With increasing temperature, the FM phase is gradually transformed to the AFM one. The NTE phenomenon occurs in the present (Hf,Ti)Fe 2 because of the fact that the unit cell volume of the AFM phase is smaller than that of the FM phase, and the mass fraction of the AFM phase increases with increasing temperature. The construction of phase coexistence can be a method to achieve NTE materials in future studies.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Tuning infrared plasmon resonances in doped metal-oxide nanocrystals through cation-exchange reactions
Metal-oxide nanocrystals doped with aliovalent atoms can exhibit tunable infrared localized surface plasmon resonances (LSPRs). Yet, the range of dopant types and concentrations remains limited for many metal-oxide hosts, largely because of the difficulty in establishing reaction kinetics that favors dopant incorporation by using the co-thermolysis method. Here we develop cation-exchange reactions to introduce p-type dopants (Cu + , Ag + , etc.) into n-type metal-oxide nanocrystals, producing programmable LSPR redshifts due to dopant compensation. We further demonstrate that enhanced n-type doping can be realized via sequential cation-exchange reactions mediated by the Cu + ions. Cation-exchange transformations add a new dimension to the design of plasmonic nanocrystals, allowing preformed nanocrystals to be used as templates to create compositionally diverse nanocrystals with well-defined LSPR characteristics. The ability to tailor the doping profile postsynthetically opens the door to a multitude of opportunities to deepen our understanding of the relationship between local structure and LSPR properties.
29 ENERGY PLANNING, POLICY, AND ECONOMY↗
Inorganic–organic hybridization induced uniaxial zero thermal expansion in MC 4 O 4 (M = Ba, Pb)
We report two inorganic–organic hybrid materials with pillar-layered architectures, BaC 4 O 4 and PbC 4 O 4 , which show uniaxial zero thermal expansion (ZTE) along the hybrid direction over a wide temperature range.
36 MATERIALS SCIENCE↗
Negative thermal expansion in cubic FeFe(CN) 6 Prussian blue analogues
Negative thermal expansion (NTE) behavior is an interesting physical phenomenon, but the number of NTE materials is limited. In this study, a new NTE compound has been found, FeFe(CN) 6 Prussian blue analogue, where the average linear coefficient of thermal expansion (α l ) is –4.260 × 10 –6 K –1 between 100 and 450 K. The NTE properties and local vibration dynamics have been investigated by joint experiments of synchrotron X-ray diffraction, X-ray pair distribution function, and extended X-ray absorption fine structure spectroscopy. It has been observed that the Fe–C/Fe–N bonds expand with increasing temperature, while the unit cell shrinks in FeFe(CN) 6 . The vibration directions of both Fe–C and Fe–N prefer to be perpendicular to the linkage of Fe–C[≡]N–Fe rather than being parallel. More pieces of evidence indicate that the transverse vibrations of N atoms dominate the NTE behavior of FeFe(CN) 6 . In conclusion, the present results prove directly that the transverse thermal vibrations of C and N atoms are crucial for the occurrence of the NTE of Prussian blue analogues.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Aerosol hygroscopic growth, contributing factors, and impact on haze events in a severely polluted region in northern China
This study investigates the impact of the aerosol hygroscopic growth effect on haze events in Xingtai, a heavily polluted city in the central part of the North China Plain (NCP), using a large array of instruments measuring aerosol optical, physical, and chemical properties. Key instruments used and measurements made include the Raman lidar for atmospheric water vapor content and aerosol optical profiles, the PC-3016A GrayWolf six-channel handheld particle and mass meter for atmospheric total particulate matter (PM) that has diameters less than 1 and 2.5 µ m (PM 1 and PM 2.5 , respectively), the aerosol chemical speciation monitor (ACSM) for chemical components in PM 1 , and the hygroscopic tandem differential mobility analyzer (H-TDMA) for aerosol hygroscopicity. The changes in PM 1 and PM 2.5 agreed well with that of the water vapor content due to the aerosol hygroscopic growth effect. Two cases were selected to further analyze the effects of aerosol hygroscopic growth on haze events. The lidar-estimated hygroscopic enhancement factor for the aerosol backscattering coefficient during a relatively clean period (Case I) was lower than that during a pollution event (Case II) with similar relative humidity (RH) levels of 80 %–91 %. The Kasten model was used to fit the aerosol optical hygroscopic growth factor (GF) whose parameter b differed considerably between the two cases, i.e., 0.1000 (Case I) versus 0.9346 (Case II). The aerosol acidity value calculated from ACSM data for Case I (1.35) was less than that for Case II (1.50) due to different amounts of inorganics such as NH 4 NO 3 , NH 4 HSO 4 , and (NH 4 ) 2 SO 4 . Model results based on H-TDMA data showed that aerosol hygroscopic growth factors in each size category (40, 80, 110, 150, and 200 nm) at different RH levels (80 %–91 %) for Case I were lower than those for Case II. For similar ambient RH levels, the high content of nitrate facilitates the hygroscopic growth of aerosols, which may be a major factor contributing to heavy haze episodes in Xingtai.
Chen, Jun↗
Large Negative Thermal Expansion Induced by Synergistic Effects of Ferroelectrostriction and Spin Crossover in PbTiO 3 -Based Perovskites
The discovery of unusual negative thermal expansion (NTE) provides the opportunity to control the common but much desired property of thermal expansion, which is valuable not only in scientific interests but also in practical applications. However, most of the available NTE materials are limited to a narrow temperature range, and the NTE effect is generally weakened by various modifications. Here, we report an enhanced NTE effect that occurs over a wide temperature range ($\overline{αV}$ = -5.24 × 10 -5 °C -1 , 25-575 °C), and this NTE effect is accompanied by an abnormal enhanced tetragonality, a large spontaneous polarization, and a G-type antiferromagnetic ordering in the present perovskite-type ferroelectric of (1-x)PbTiO 3 -xBiCoO 3 . Specifically, for the composition of 0.5PbTiO 3 -0.5BiCoO 3 , an extensive volumetric contraction of ~4.8 % has been observed near the Curie temperature of 700 °C, which represents the highest level in PbTiO 3 -based ferroelectrics. According to our experimental and theoretical results, the large NTE originates from a synergistic effect of the ferroelectrostriction and spin crossover of cobalt on the crystal lattice. The actual NTE mechanism is contrasted with previous functional NTE materials, in which the NTE is simply coupled with one ordering such as electronic, magnetic, or ferroelectric ordering. In conclusion, the present study sheds light on the understanding of NTE mechanisms, and it attests that NTE could be simultaneously coupled with different orderings, which will pave a new way toward the design of large NTE materials.
36 MATERIALS SCIENCE↗
On the stability of Einstein static universe in general scalar–tensor theory with non-minimal derivative coupling
The emergent scenario claims that our universe stems from an Einstein static universe, and provides a possible way to avoid the big bang singularity. A successful Einstein static universe requires to be stable past eternally against both homogeneous and inhomogeneous scalar perturbations. In this paper, we study the stability of Einstein static universes in general scalar–tensor theory with non-minimal derivative coupling by analyzing scalar and tensor perturbations. Our results show that the Einstein static solutions are stable against both scalar and tensor perturbations, and the emergent scenario is viable to avoid the initial singularity in this theory.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Charge transfer drives anomalous phase transition in ceria
Ceria has conventionally been thought to have a cubic fluorite structure with stable geometric and electronic properties over a wide temperature range. Here we report a reversible tetragonal (P4 2 /nmc) to cubic (Fm-3m) phase transition in nanosized ceria, which triggers negative thermal expansion in the temperature range of -25 °C–75 °C. Local structure investigations using neutron pair distribution function and Raman scatterings reveal that the tetragonal phase involves a continuous displacement of O 2- anions along the fourfold axis, while the first-principles calculations clearly show oxygen vacancies play a pivotal role in stabilizing the tetragonal ceria. Further experiments provide evidence of a charge transfer between oxygen vacancies and 4f orbitals in ceria, which is inferred to be the mechanism behind this anomalous phase transition.
36 MATERIALS SCIENCE↗
Synergy between phase transformation and domain switching in two morphotropic phase boundary ferroelectrics
We present that many applications of ferroic materials take advantage of the microstructural redistribution under an external stimulus. Despite extensive studies on the microstructural evolution during both domain switching and phase transformations of high-performance ferroelectrics near morphotropic phase boundaries (MPBs), the synergetic interactions between both leading factors remain unclear. Herein, we have illustrated and discerned the correlative response of phase transformation and domain switching in an archetypical piezoceramic of PbTiO 3 -BiScO 3 using a combination of in situ high-energy synchrotron x-ray diffraction and phase-field simulations. The direct structural evidence and domain development from simulations reveal a significant reversible orientation-dependent emerging phase transformation and enhanced domain switching. Increasingly populated polarization variants aligned with the applied electric field owing to this strong synergistic interaction play an important role in enhancing the piezoelectric performances of MPB ferroelectrics. Lastly, in addition to providing further insight into the microstructures of ferroelectrics, the present results have the potential to guide the design of high-performance materials.
36 MATERIALS SCIENCE↗