High-frequency supercapacitors are being studied with the aim to replace the bulky electrolytic capacitors for current ripple filtering and other functions used in power systems. Here, 3 D edge-oriented graphene(EOG)w...High-frequency supercapacitors are being studied with the aim to replace the bulky electrolytic capacitors for current ripple filtering and other functions used in power systems. Here, 3 D edge-oriented graphene(EOG)was grown encircling carbon nanofiber(CNF) framework to form a highly conductive electrode with a large surface area. Such EOG/CNF electrodes were tested in aqueous and organic electrolytes for high-frequency supercapacitor development. For the aqueous and the organic cell, the characteristic frequency at-45° phase angle was found to be as high as 22 and 8.5 k Hz, respectively. At 120 Hz, the electrode capacitance density was 0.37 and 0.16 m F cm^(-2) for the two cells. In particular, the 3 V high-frequency organic cell was successfully tested as filtering capacitor used in AC/DC converter, suggesting the promisingpotential of this technology for compact power supply design and other applications.展开更多
We discuss how recent advances in phase-recovery imaging techniques in combination with plasmonic UTSs （ultrathin condensers） with a semiconductor substrate have paved the way for the development of novel optical na...We discuss how recent advances in phase-recovery imaging techniques in combination with plasmonic UTSs （ultrathin condensers） with a semiconductor substrate have paved the way for the development of novel optical nanoscopes. These optical nanoscopes are capable of imaging the intensity and the phase of the electric field distribution at the sample＇s plane.展开更多
An intriguing quasi-relativistic wave equation, which is useful between the range of applications of the Schr<span style="white-space:nowrap;">ö</span>dinger and the Klein-Gordon equatio...An intriguing quasi-relativistic wave equation, which is useful between the range of applications of the Schr<span style="white-space:nowrap;">ö</span>dinger and the Klein-Gordon equations, is discussed. This equation allows for a quantum description of a constant number of spin-0 particles moving at quasi-relativistic energies. It is shown how to obtain a Pauli-like version of this equation from the Dirac equation. This Pauli-like quasi-relativistic wave equation allows for a quantum description of a constant number of spin-1/2 particles moving at quasi-relativistic energies and interacting with an external electromagnetic field. In addition, it was found an excellent agreement between the energies of the electron in heavy Hydrogen-like atoms obtained using the Dirac equation, and the energies calculated using a perturbation approach based on the quasi-relativistic wave equation. Finally, it is argued that the notable quasi-relativistic wave equation discussed in this work provides interesting pedagogical opportunities for a fresh approach to the introduction to relativistic effects in introductory quantum mechanics courses.展开更多
Some consequences, due to the existence of a pair of decoupled Schrödinger-like but relativistic quantum mechanics wave equations, are explored. It is shown that one equation directly describes the quantum st...Some consequences, due to the existence of a pair of decoupled Schrödinger-like but relativistic quantum mechanics wave equations, are explored. It is shown that one equation directly describes the quantum states of a single spin-0 particle, and the other one indirectly describes the quantum states of the corresponding antiparticle. In correspondence with the matter-antimatter symmetry, for a Coulomb potential, a charge conjugation operation transforms the second equation in the first one. However, if a particle could interact with itself (gravitationally or electrically) due to the spread of its wavefunction, the C-symmetry could be broken;therefore, matter and antimatter could be distinguished. Under these assumptions, it is deducted the impossibility of the existence of particles and antiparticles with a mass larger than the Plank mass (m<sub>P</sub>), or with the absolute value of the charge larger than the Plank charge (q<sub>P</sub>). It is proposed the existence of primordial antimatter electrical sinks. It is also suggested that all macroscopic matter objects with a mass m > m<sub>P</sub>, and all macroscopic antimatter bodies with a charge |q| > q<sub>P</sub> should not be quantum but classical objects. It is argued that these findings could explain the absence of antimatter with a complicated structure and partially explain the excess of charged matter in the known Universe.展开更多
Two pure hexagonal phases of titanium dioxide, anatase and rutile, were grown on c-cut Al2O3 substrates via pulsed-laser deposition by changing only the growth and annealing conditions, but without changing the substr...Two pure hexagonal phases of titanium dioxide, anatase and rutile, were grown on c-cut Al2O3 substrates via pulsed-laser deposition by changing only the growth and annealing conditions, but without changing the substrate, target, or working gas. Purity of each phase was confirmed by x-ray diffraction, the quality of each film was studied using atomic force microscopy and scanning electron microscopy, and the interface between each substrate and film was studied using x-ray photoelectron spectroscopy. A binding layer of Ti2O3 was found to explain anatase growth under the very large lattice mismatch conditions.展开更多
The basic equations of the non-relativistic quantum mechanics with trajectories and quantum hydrodynamics are extended to the relativistic domain. This is achieved by using a Schr<span style="white-space:nowra...The basic equations of the non-relativistic quantum mechanics with trajectories and quantum hydrodynamics are extended to the relativistic domain. This is achieved by using a Schr<span style="white-space:nowrap;">?</span>dinger-like equation, which describes a particle with mass and spin-0 and with the correct relativistic relation between its linear momentum and kinetic energy. Some simple but instructive free particle examples are discussed.展开更多
A Schrödinger-like equation for a single free quantum particle is presented. It is argued that this equation can be considered a natural relativistic extension of the Schrödinger equation for energie...A Schrödinger-like equation for a single free quantum particle is presented. It is argued that this equation can be considered a natural relativistic extension of the Schrödinger equation for energies smaller than the energy associated to the particle’s mass. Some basic properties of this equation: Galilean invariance, probability density, and relation to the Klein-Gordon equation are discussed. The scholastic value of the proposed Grave de Peralta equation is illustrated by finding precise quasi-relativistic solutions for the infinite rectangular well and the quantum rotor problems. Consequences of the non-linearity of the proposed equation for the quantum superposition principle are discussed.展开更多
Using the Hamilton-Jacobi and the Lagrange formalisms, a pair of relativistic quantum mechanics equations are obtained by abduction. These equations, in contrast with the Klein-Gordon and other relativistic quantum me...Using the Hamilton-Jacobi and the Lagrange formalisms, a pair of relativistic quantum mechanics equations are obtained by abduction. These equations, in contrast with the Klein-Gordon and other relativistic quantum mechanics equations, have no solutions with both positive and negative kinetic energies. The equation with solutions with only positive kinetic energy values describes a spin-0 particle of mass m, which is moving at relativistic speeds in a scalar potential. The wavefunctions and the energies corresponding to the associated antiparticle can be obtained by solving the other equation, which only has solutions with negative kinetic energy values.展开更多
Polysulfide shuttle effect,causing extremely low Coulombic efficiency and cycling stability,is one of the toughest challenges hindering the development of practical lithium sulfur batteries(LSBs).Introducing catalytic...Polysulfide shuttle effect,causing extremely low Coulombic efficiency and cycling stability,is one of the toughest challenges hindering the development of practical lithium sulfur batteries(LSBs).Introducing catalytic nanostructures to stabilize the otherwise soluble polysulfides and promote their conversion to solids has been proved to be an effective strategy in attacking this problem,but the heavy mass of catalysts often results in a low specific energy of the whole electrode.Herein,by designing and synthesizing a free-standing edge-oriented NiCo_(2)S_(4)/vertical graphene functionalized carbon nanofiber(NCS/EOG/CNF)thin film as a catalytic overlayer incorporated in the sulfur cathode,the polysulfide shuttle effect is largely alleviated,revealed by the enhanced electrochemical performance measurements and the catalytic function demonstration.Different from other reports,the NiCo_(2)S_(4)nanosheets synthesized here have a 3-D edge-oriented structure with fully exposed edges and easily accessible in-plane surfaces,thus providing a high density of active sites even with a small mass.The EOG/CNF scaffold further renders the high conductivity in the catalytic structure.Combined,this novel structure,with high sulfur loading and high sulfur fraction,leads to high-performance sulfur cathodes toward a practical LSB technology.展开更多
基金supported by the National Science Foundation(1611060)
文摘High-frequency supercapacitors are being studied with the aim to replace the bulky electrolytic capacitors for current ripple filtering and other functions used in power systems. Here, 3 D edge-oriented graphene(EOG)was grown encircling carbon nanofiber(CNF) framework to form a highly conductive electrode with a large surface area. Such EOG/CNF electrodes were tested in aqueous and organic electrolytes for high-frequency supercapacitor development. For the aqueous and the organic cell, the characteristic frequency at-45° phase angle was found to be as high as 22 and 8.5 k Hz, respectively. At 120 Hz, the electrode capacitance density was 0.37 and 0.16 m F cm^(-2) for the two cells. In particular, the 3 V high-frequency organic cell was successfully tested as filtering capacitor used in AC/DC converter, suggesting the promisingpotential of this technology for compact power supply design and other applications.
文摘We discuss how recent advances in phase-recovery imaging techniques in combination with plasmonic UTSs （ultrathin condensers） with a semiconductor substrate have paved the way for the development of novel optical nanoscopes. These optical nanoscopes are capable of imaging the intensity and the phase of the electric field distribution at the sample＇s plane.
文摘An intriguing quasi-relativistic wave equation, which is useful between the range of applications of the Schr<span style="white-space:nowrap;">ö</span>dinger and the Klein-Gordon equations, is discussed. This equation allows for a quantum description of a constant number of spin-0 particles moving at quasi-relativistic energies. It is shown how to obtain a Pauli-like version of this equation from the Dirac equation. This Pauli-like quasi-relativistic wave equation allows for a quantum description of a constant number of spin-1/2 particles moving at quasi-relativistic energies and interacting with an external electromagnetic field. In addition, it was found an excellent agreement between the energies of the electron in heavy Hydrogen-like atoms obtained using the Dirac equation, and the energies calculated using a perturbation approach based on the quasi-relativistic wave equation. Finally, it is argued that the notable quasi-relativistic wave equation discussed in this work provides interesting pedagogical opportunities for a fresh approach to the introduction to relativistic effects in introductory quantum mechanics courses.
文摘Some consequences, due to the existence of a pair of decoupled Schrödinger-like but relativistic quantum mechanics wave equations, are explored. It is shown that one equation directly describes the quantum states of a single spin-0 particle, and the other one indirectly describes the quantum states of the corresponding antiparticle. In correspondence with the matter-antimatter symmetry, for a Coulomb potential, a charge conjugation operation transforms the second equation in the first one. However, if a particle could interact with itself (gravitationally or electrically) due to the spread of its wavefunction, the C-symmetry could be broken;therefore, matter and antimatter could be distinguished. Under these assumptions, it is deducted the impossibility of the existence of particles and antiparticles with a mass larger than the Plank mass (m<sub>P</sub>), or with the absolute value of the charge larger than the Plank charge (q<sub>P</sub>). It is proposed the existence of primordial antimatter electrical sinks. It is also suggested that all macroscopic matter objects with a mass m > m<sub>P</sub>, and all macroscopic antimatter bodies with a charge |q| > q<sub>P</sub> should not be quantum but classical objects. It is argued that these findings could explain the absence of antimatter with a complicated structure and partially explain the excess of charged matter in the known Universe.
文摘Two pure hexagonal phases of titanium dioxide, anatase and rutile, were grown on c-cut Al2O3 substrates via pulsed-laser deposition by changing only the growth and annealing conditions, but without changing the substrate, target, or working gas. Purity of each phase was confirmed by x-ray diffraction, the quality of each film was studied using atomic force microscopy and scanning electron microscopy, and the interface between each substrate and film was studied using x-ray photoelectron spectroscopy. A binding layer of Ti2O3 was found to explain anatase growth under the very large lattice mismatch conditions.
文摘The basic equations of the non-relativistic quantum mechanics with trajectories and quantum hydrodynamics are extended to the relativistic domain. This is achieved by using a Schr<span style="white-space:nowrap;">?</span>dinger-like equation, which describes a particle with mass and spin-0 and with the correct relativistic relation between its linear momentum and kinetic energy. Some simple but instructive free particle examples are discussed.
文摘A Schrödinger-like equation for a single free quantum particle is presented. It is argued that this equation can be considered a natural relativistic extension of the Schrödinger equation for energies smaller than the energy associated to the particle’s mass. Some basic properties of this equation: Galilean invariance, probability density, and relation to the Klein-Gordon equation are discussed. The scholastic value of the proposed Grave de Peralta equation is illustrated by finding precise quasi-relativistic solutions for the infinite rectangular well and the quantum rotor problems. Consequences of the non-linearity of the proposed equation for the quantum superposition principle are discussed.
文摘Using the Hamilton-Jacobi and the Lagrange formalisms, a pair of relativistic quantum mechanics equations are obtained by abduction. These equations, in contrast with the Klein-Gordon and other relativistic quantum mechanics equations, have no solutions with both positive and negative kinetic energies. The equation with solutions with only positive kinetic energy values describes a spin-0 particle of mass m, which is moving at relativistic speeds in a scalar potential. The wavefunctions and the energies corresponding to the associated antiparticle can be obtained by solving the other equation, which only has solutions with negative kinetic energy values.
基金the National Science Foundation of USA(1931737).
文摘Polysulfide shuttle effect,causing extremely low Coulombic efficiency and cycling stability,is one of the toughest challenges hindering the development of practical lithium sulfur batteries(LSBs).Introducing catalytic nanostructures to stabilize the otherwise soluble polysulfides and promote their conversion to solids has been proved to be an effective strategy in attacking this problem,but the heavy mass of catalysts often results in a low specific energy of the whole electrode.Herein,by designing and synthesizing a free-standing edge-oriented NiCo_(2)S_(4)/vertical graphene functionalized carbon nanofiber(NCS/EOG/CNF)thin film as a catalytic overlayer incorporated in the sulfur cathode,the polysulfide shuttle effect is largely alleviated,revealed by the enhanced electrochemical performance measurements and the catalytic function demonstration.Different from other reports,the NiCo_(2)S_(4)nanosheets synthesized here have a 3-D edge-oriented structure with fully exposed edges and easily accessible in-plane surfaces,thus providing a high density of active sites even with a small mass.The EOG/CNF scaffold further renders the high conductivity in the catalytic structure.Combined,this novel structure,with high sulfur loading and high sulfur fraction,leads to high-performance sulfur cathodes toward a practical LSB technology.
