One-dimensional Layered Structures Research Articles

Synthesis of Co/Ni-MOFs with mixed ligands and their Oxygen Evolution Reaction (OER) performance

Two new transition metal–organic framework (MOF) complexes, Co-MOF (C28H17CoN6O9S2) and Ni-MOF (C28H6NNi8O2S0.06), were synthesized using a hydrothermal method. Upon characterization and analysis, Co-MOF and Ni-MOF showed similar structures, in which Co2+ or Ni2+ coordinated with two pyridine-2,6-dicarboxylic acid ligands to form octahedral geometric configurations, which in turn formed one-dimensional layered structure, while Py2TTz ligands existed between these layers to enlarge the pore size of MOFs. Co-MOF showed superior performance than Ni-MOF in the OER process, with a low overpotential (227 mV) and Tafel slope (51.4 mV dec‑1) at 10 mA cm-2 current density. This work provided new insight into designing transition MOFs for electrocatalytic water splitting.

Integration of tunable solar spectral directional absorption and switchable near-infrared transmission filters based on phase-change materials

In this work, we propose a one-dimensional layered structure to realize the integration of various applications of solar energy spectrum based on phase-change materials (PCMs). Through the effective combination of PCMs and the designed structure, a tunable solar spectral directional absorption and switchable near-infrared band sensor can be simultaneously obtained on one sample. The research provides creative possibility for the applications of angle and polarization information of solar spectrum and narrowband filtering sensing.

Approaching multi-band and broadband high absorption based on one-dimensional layered structures containing monolayer MoS2

MoS2 has attracted considerable attention owing to its unusual and intriguing potential applications in optoelectronic devices. In this study, the absorption properties of a simple one-dimensional (1D) layered structure composed of monolayer MoS2 are analyzed by transfer matrix method. The dielectric permittivity of monolayer MoS2 is employed using the Lorentz model. The influences contributed to the period of the structure and the incident angle are numerically investigated. Our results indicate that a tunable multi-band (broadband) absorber can be achieved by using such a 1D layered structure. A multi-band (broadband) absorption phenomenon can be obtained by increasing the period of the structure. Furthermore, the absorption peaks and broadband absorptance spectra have blue-shifted as the incident angle increases.

One-Dimensional Layered Structures as Precursors for the Fabrication of Nanostructured Lithium Titanate Spinel-Based Composites

One-Dimensional Layered Structures as Precursors for the Fabrication of Nanostructured Lithium Titanate Spinel-Based Composites

Theoretical Investigation of a Sensor Based on One-Dimensional Photonic Crystals to Measure Four Physical Quantities

In this study, a sensor based on the located defect mode resonance is proposed, which can be used to simultaneously measure changes in magnetic induction intensity, plasma density, refractive index, and incident light angle. Plasma is introduced as the defect into a one-dimensional periodic structure, exciting the located defect mode resonance. The sensitivity, linear range, and figure of merit of the sensor are investigated using the transfer matrix method. The increase in the number of cycles can be used to improve the quality factor and FOM. We also consider the influence of the loss tangent on the sensor to a certain extent. The one-dimensional layered structure is utilized, which has the merits of small volume and simple manufacture. In addition, compared with the traditional sensors design, which focuses on the improvement of performance parameters, our proposed sensor concentrates on the study of multiple physical quantities. Therefore, we hope that our work can have some application potential in the field of measurement.

A model of human skin under large amplitude oscillatory shear

Skin mechanics is of importance in various fields of research when accurate predictions of the mechanical response of skin is essential. This study aims to develop a new constitutive model for human skin that is capable of describing the heterogeneous, nonlinear viscoelastic mechanical response of human skin under shear deformation. This complex mechanical response was determined by performing large amplitude oscillatory shear (LAOS) experiments on ex vivo human skin samples. It was combined with digital image correlation (DIC) on the cross-sectional area to assess heterogeneity. The skin is modeled as a one-dimensional layered structure, with every sublayer behaving as a nonlinear viscoelastic material. Heterogeneity is implemented by varying the stiffness with skin depth. Using an iterative parameter estimation method all model parameters were optimized simultaneously. The model accurately captures strain stiffening, shear thinning, softening effect and nonlinear viscous dissipation, as experimentally observed in the mechanical response to LAOS. The heterogeneous properties described by the model were in good agreement with the experimental DIC results. The presented mathematical description forms the basis for a future constitutive model definition that, by implementation in a finite element method, has the capability of describing the full 3D mechanical behavior of human skin.

Acoustic properties of a layered porous elastic structure saturated with a Maxwell fluid

We consider a one-dimensional layered structure that consists of an elastic material and a Maxwell fluid. It is assumed that the width of the layers is small compared with the size of the domain, where the problem is being solved. By employing the Nguetseng two-scale convergence technique, we have homogenized the equations that describe the mechanical system. For the homogenized equation, the limit cases of the Maxwell fluid with the small viscosity and with the small relaxation time are considered. The question of existence of the travelling wave solution for the homogenized equation is investigated.

Analytical Sensor Response Function of Viscosity Sensors Based on Layered Piezoelectric Thickness Shear Resonators

Resonant piezoelectric sensors based on bulk acoustic wave (BAW) thickness shear resonators are promising for the inline measurement of fluid viscosity, e.g., in industrial processes. The sensor response function can be derived from the general rigorous transfer matrix description of one-dimensional layered structures consisting of piezoelectric and non-piezoelectric layers of arbitrary number. This model according to Nowotny et al. provides a complete analytical description of the electrical and mechanical behaviour of such structures with two electrodes and arbitrary acoustic termination impedances (Rig-1d-Model). We apply this model to derive the sensor response functions and the mechanical displacement curves of the following configurations appropriate for viscosity sensors:(a)An AT cut quartz crystal plate in contact with vacuum at the backside plane and with the liquid under investigation at the front side plane (QL).(b)An AT cut quartz crystal in contact with the liquid under investigation at both sides (LQL).It is shown that in the QL case the originally only heuristically introduced and well established sensor response function according to Kanasawa can be derived from the Rig-1d-Model by introducing minor approximations. Experimental results are presented for the LQL configuration using an N1000 viscosity reference oil as test fluid.

Controllable molecular aggregation and fluorescence properties of 1,3,4-oxadiazole derivatives

In H-aggregation, BOXD-6 adopts a linear conformation and forms a one-dimensional layered structure; in J-aggregation, it adopts a Z-shaped conformation and forms a more ordered two-dimensional layered structure.

Synthesis and structural characterization of new dinuclear silver(I) complexes: Different coordination modes of substituted 1,2,4-triazine ligands

Abstract Two new binuclear silver(I) complexes of 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine (PDT) and 3,5,6-tris(2-pyridyl)-1,2,4-triazine (TPT) ligands, [Ag2(PDT)2(NO3)2], 1, and [Ag2(TPT)2(NO3)2], 2, have been synthesized and characterized by elemental analysis, IR and 1H NMR spectroscopy, and also studied by thermal and electrochemical analysis as well as by X-ray crystallography. The individual dinuclear complexes in 1 are extended into a one-dimensional layered structure by weak Ag···CPDT (η3) interactions. The interesting features of the Ag(I) complexes are the different coordination modes of the ligands. The supramolecular features in these complexes are controlled by weak directional intra and intermolecular interactions.

Compression and amplification of an ultrasonic pulse reflected from a one-dimensional layered structure

Compression of ultrasonic pulses reflected from layered structures is studied. A short pulse is emitted into water towards a structure consisting of solid plates backed with an air layer. Due to multiple reflections in the structure, the signal is elongated. The reflected signal is received by the same transducer and digitized. After that, the wave is reversed in time and emitted towards the layered structure for the second time; then, the reflected signal is received. Due to the invariance of the processes under the time reversal, the pulse is compressed by the structure: the reflected signal becomes shorter and acquires the waveform of the initial pulse. The possibility of an efficient compression of signals is demonstrated experimentally. Numerical simulations show that the use of more complex structures can considerably increase the compression ratio and produce short signals of a much higher amplitude than that emitted by the transducer. An efficient compression algorithm is proposed.

Vectorial modal analysis of dielectric waveguides based on a coupled transverse-mode integral equation I Mathematical formulation

We propose a rigorous full-vector integral-equation formulation for analyzing modal characteristics of the complex, two-dimensional, rectangular-like dielectric waveguide that is divisible into vertical slices of one-dimensional layered structures. The entire electromagnetic mode field is completely determined by the y-component electric and magnetic field functions on the interfaces between slices. These interfacial functions are governed by a system of vector-coupled transverse-mode integral equations (VCTMIE) whose kernels are made of orthonormal sets of both TE-to-y and TM-to-y modes from each slice. To solve for the unknown functions, we construct sets of suitable expansion functions and turn VCTMIE into a nonlinear matrix equation via orthogonal projection. The eigenvectors of the matrix provide the mode field solutions of the complex dielectric waveguide.

An all-optical switch based on a one-dimensional layered structure with defocusing nonlinearity

The feasibility of an optical switch of femtosecond range controlled by a femtosecond light pulse acting on a nonlinear one-dimensional photonic crystal (a layered one-dimensional periodic structure) is demonstrated by computer simulation. The crystal comprises linear and weakly defocusing layers. It is shown that switching occurs when the peak intensity of the initial pulse exceeds a certain threshold value due to the dependence of the transmission-reflection bands of the photonic crystal on the nonlinearity of the medium.

Relationship between the superprism effect in one-dimensional photonic crystals and spatial dispersion in nonperiodic thin-film stacks

We derive that, in all-pass (unity amplitude transmittance or reflectance) one-dimensional layered structures, the tangent of the group-propagation angle, the group delay, and the stored energy are approximately proportional. Thus photonic crystal superprisms and spatial dispersion in nonperiodic photonic nanostructures are generally related to wavelength-dependent stored energy in the stack.

Omnidirectional elastic band gap in finite lamellar structures.

This paper presents a comprehensive theoretical analysis of the occurrence of omnidirectional reflection in one-dimensional phononic crystal structures. We discuss the conditions for a one-dimensional layered structure, made of elastic materials, to exhibit total reflection of acoustic incident waves in a given frequency range, for all incident angles and all polarizations. The property of omnidirectional reflection can be fulfilled with a simple finite superlattice if the substrate from which the incident waves are launched is made of a material with high acoustic velocities (this is very similar to the case of omnidirectional optical mirror where the incident light is generated in vacuum). However, if the substrate is made of a material with low acoustic velocities, we propose two solutions to obtain an omnidirectional band gap, namely, the cladding of a superlattice with a layer of high acoustic velocities, which acts like a barrier for the propagation of phonons, or the association in tandem of two different superlattices in such a way that the superposition of their band structures exhibits an absolute acoustic band gap. We discuss the appropriate choices of the material and geometrical properties to realize such structures. The behavior of the transmission coefficients are discussed in relation with the dispersion curves of the finite structure embedded between two substrates. Both transmission coefficients and densities of states (from which we derive the dispersion curves) are calculated in the framework of a Green's function method.

Transient development of instabilities in bounded shear flow of granular materials

A study has been conducted on the analysis and fate of instabilities arising from rapid shear flow of a granular material. Specifically, this study is made through a detailed analysis of continuum rheological models, to examine whether the initiation and growth of the instabilities predicted by this analysis are consistent with the linear stability theory. It is found that rapidly sheared particles tend to form alternating bands or clusters of high and low solid concentrations. Two types of standing-wave instabilities, namely layering and stationary modes, are investigated. The fate of these density waves is tracked through transient integration of the macroscopic balance equations, and examined by a fast Fourier transform (FFT) analysis. In such a formulation, a few characteristic modes with different wave numbers have been identified. The temporal evolution of the intensity of fluctuating energy is investigated by analyzing the most dominant mode in the system. It is found that the structure and dynamics of the resulting waves can be quantitatively correlated with the power spectrum density of concentration fluctuations. The development of the layering mode is governed primarily by linear instability. On the other hand, clusters of particles of the stationary mode may stretch and interact with neighboring clusters. This new finding indicates that the transient development of a two-dimensional stationary disturbance may ultimately lead to a one-dimensional layered structure. The stationary and layering perturbations eventually evolve to a similar structure and the stationary perturbation leads the system to the layered state more rapidly than the layering mode.

Layered piezoelectric resonators with an arbitrary number of electrodes (general one-dimensional treatment)

A general transfer matrix description for one-dimensional layered structures consisting of piezoelectric and nonpiezoelectric anisotropic layers of arbitrary number is used to calculate the electrical admittance matrix for such resonators with N electrodes. The calculation is done in detail for linearly stacked resonators with two free surfaces as well as for ring resonators with a closed acoustical path. Experimental and theoretical results are given and compared for a ring resonator with two piezoelectric layers excited by four electrodes. Such a configuration can be used to generate unidirectional resonant waves.

Simulation of soil nitrogen dynamics using the SOILN model

A model dealing with transport and transformations of nitrogen in soil is briefly described. The model has a one-dimensional layered structure and considers processes such as plant uptake, mineralization/ immobilization, leaching and denitrification. A soil water and heat model provides daily values for abiotic conditions, which are used as driving variables in the nitrogen simulation. In this study, the model was run with data from a polder-soil area in the Netherlands, with winter wheat as the crop. The simulation results showed that if a measured time course of crop nitrogen uptake throughout the growing season is available, mineral-N dynamics in soil can be satisfactorily described with this model. The main problems identified in the simulations were related to the partitioning between above- and below-ground plant-N, and supplying the crop with sufficient N, as given by the measurements.

Simulated nitrogen dynamics and losses in a layered agricultural soil

A soil nitrogen model emphasizing mineral nitrogen dynamics and losses is presented. The model has a one-dimensional layered structure and considers plant uptake, mineralization, immobilization, leaching and denitrification processes. Fertilization and manure additions are included as management inputs. A physically based soil-water and heat model provides daily values of temperature, unfrozen water content, water flow and drainage, at different depths in the profile. Input data requirements include standard meteorological variables, basic soil physical and biological properties and crop management characteristics. Soil nitrogen dynamics were simulated for a 3-year period in N-fertilized and unfertilized barley. Model predictions were compared with measurements of nitrate leaching and mineral N content of the soil. Simulation of mineral N levels and leaching generally agreed with field data. Prediction of mineral N dynamics in both N-fertilized and unfertilized barley was better for surface layers than for deeper layers in the profile. Discrepancies between simulated and measured mineral N content in the topsoil were mainly related to mineralization and plant uptake. In deeper soil layers, differences between measured and predicted values were primarily related to the water flow and the drainage pathway. Simulated amounts of nitrate leached were close to measured values. Discrepancies in the temporal distribution of nitrate leached were mainly attributable to the simulated water flow. The model predicted that nitrate leaching to drainage tiles occurred mainly from the upper layers. Prediction of leaching depended as much on the simulation of drainage flow pathways and the vertical distribution of nitrate in the profile as on the simulation of water flow rates.