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We consider a double-layer structure consisting of a bilayer graphene sheet and a two-dimensional electron gas, isolated in a very thin GaAs quantum well. The collective excitations are determined from the zeroes of the dynamical dielectric function within the random-phase approximation, taking into account the temperature effects. Numerical calculations present that two plasmon modes exist in the system, similar to those in other double-layer structures. While the optical mode continues in the interband single-particle excitation area, the acoustic mode only crosses the intraband single-particle excitation boundary and disappears. Also, our investigations show that plasmon properties in the system are affected significantly by most of the chosen factors. Plasmon frequency increases as the separation increases while the increase in carrier density decreases noticeably these frequencies. Temperature affects plasmon characters similarly to but more weakly than that does in monolayer grapheme—two-dimensional electron gas double-layer structures. Finally, the temperature can increase the effects of some other parameters on plasmon properties of the system, so this factor should be taken into account in calculations to improve the model for better results.

The purpose of the research is to assess the sound absorption performance (SAP) of acoustic metamaterials made of double-layer Nomex honeycomb structures in which a micro-orifice corresponds to a honeycomb unit. For this purpose, the influences of structural parameters on the SAP of acoustic metamaterials were investigated by using experimental testing and a validated theoretical model. In addition, the sandwich structure was optimized by the genetic algorithm. The research shows that the panel thickness and micro-orifice diameter mainly affect the second resonant frequency and second peak sound absorption coefficient (SAC) of the structure. The unit cell size is found to influence the first and second resonant frequencies and two peaks of the SAC. An extremely low side-length of the honeycomb core decreases the SAP of the structure for low-frequency noise signals. Additionally, the sandwich structure presents a better SAP when the diameter of micro-orifices on the front micro-perforated panel (MPP) exceeds that of the back MPP. The sandwich structure shows better noise reduction performance after the optimization aiming at the noise frequency outside trains.

A genetic algorithm was employed as a novel method to determine the best combination of materials for a double-layer electromagnetic shielding composite with good electromagnetic wave absorption efficiency at high frequencies from numerous magnetic materials. A carbonyl iron soft magnetic composite and a flaky FeNi soft magnetic composite were used to form the double-layer composite. The reflection and transmission parameters of the double-layer composite were measured using a vector network analyzer. The electromagnetic shielding effectiveness (SE) of the double-layer composite was calculated and analyzed. The double-layer composite was composed of two shielding materials with different electromagnetic parameters and demonstrated an excellent electromagnetic SE greater than 20 dB above 4 GHz; the ratio of the absorption efficiency (SEA) to SE (SEA/SE) was greater than 0.95, which indicates that more than 95% of the electromagnetic waves at high frequencies were attenuated by the shielding material, rather than being scattered into the surrounding environment. The double-layer composite exhibits excellent performance toward high electromagnetic waves absorption during the EMI shielding process.

The clay platelets are negatively charged, and hence, the behavior of clays is physicochemical in nature. The clay–pore liquid interaction depends upon pore medium chemistry, which is a function of many factors. Dielectric constant of the pore medium is one such important factor. The clay swelling is considered to be explained by the Gouy–Chapman theory of diffuse double layer. This paper intends to study the effect of dielectric constant of the pore fluid on the equilibrium sediment volume in light of diffuse double-layer equation of the Gouy–Chapman theory. It has been illustrated that the Gouy–Chapman theory cannot explain the equilibrium sediment volume behavior of montmorillonite and kaolinite clay minerals satisfactorily. It is also brought out that the equilibrium sediment volume behavior of these two clay minerals is quite opposite to each other.

Diffusiophoresis of a charge regulated spherical polyelectrolyte nanogel (PE) due to an externally imposed ionic concentration gradient is considered. The immobile charge density of the nanogel develops through the association/dissociation reactions of their inorganic functional groups. The nanogel is ion and fluid permeable with dielectric permittivity different from that of the surrounding electrolyte medium. This difference in dielectric permittivity creates an ion partitioning due to the difference in self energy of ions. The Nernst–Planck equation for ion transport and the Poisson equation (PNP) for the electric field are modified to take into account the ion partitioning effects. The diffusiophoresis mechanism is governed by the electrophoresis generated by the induced electric field and chemiphoresis develops due to the mitigation of counterions across the double layer of the nanogel. In addition, the convection dominated double layer polarization and the counterion condensation as well as the electroosmotic flow created by the gel immobile charge play a role in the diffusiophoresis. All these effects are incorporated through the modified PNP equations coupled with the Navier–Stokes equations. The governing equations in their full form are solved numerically through a control volume approach. Present computed solutions for the limiting cases are in good agreement with the existing solutions based on the first-order perturbation analysis. In order to illustrate the diffusiophoresis mechanism we have measured the induced electric field and effective charge density of the PE and analyzed its dependence on several electrokinetic parameters. The contribution due to chemiphoresis is low for PE compared to a rigid colloid. For a highly permeable PE the diffusiophoretic velocity increases and approaches a saturation for higher range of the PE fixed charge density. The ion partitioning effect depletes counterions in PE to manifests its diffusiophoretic velocity. The diffusiophoretic velocity of PE for pH > IEP is higher than the case for which pH

The performance of prism-based surface plasmon resonance sensor utilizing new sensing configuration composed of thin metallic (Al–Au) film coated with a thin layer of BaTiO3is investigated theoretically based on angular interrogation method. It is observed that optimizing the thickness of bimetallic (Al–Au) and BaTiO3 layers, the sensitivity of the sensor improved greatly and still can maintain its minimum reflectivity and linewidth of the SPR reflectivity curve. We also observed addition of dual layer of graphene on BaTiO3 further enhanced the sensitivity. The sensitivity of the proposed sensor is found to be 227 deg/RIU, and the FWHM of resonance curve is observed to be 4.47 deg for the thickness of 28 nm of Al, 8 nm of Au and 10 nm of BaTiO3added with double layer of graphene.

The focus of this research is spectral shifting of light using phycocyanin solution extracted from the blue-green microalga Spirulina platensis in order to increase biomass productivity of the green microalga Chlorella sp. Also, lipid and chlorophyll content of the green alga was investigated. With regard to the shift of the spectrum with the phycocyanin solution, a double layer flat panel photobioreactor and two different spectral shifting strategies were used. In each strategy, the effect of two different concentrations of the solution was investigated. In the first strategy, the light passes through the chamber containing the solution and then enters the microalga culture chamber. In the second strategy, the light first enters the culture chamber and then enters the chamber containing phycocyanin pigment. The results showed that the use of phycocyanin pigment by both strategies increased the biomass productivity (P) and the specific growth rate (μmax) with a significant difference compared to the control system; the increase in P for first strategy was up to about 69%. Moreover, the use of phycocyanin solution with a lower concentration had a greater effect on the increase of total chlorophyll content; however, the solution with a higher concentration was more successful in the production of cell lipid content. Using the phycocyanin solution as spectral converter in a double layer flat panel photobioreactor increased the biomass productivity and chlorophyll content.

A composite double-layer honeycomb sandwich structure is proposed to improve the impact resistance of fillers in helicopter rotors, 44 groups of those structures are numerically simulated by LS-DYNA finite element analysis software. An approximate expression for fracture energy of the composite structure is derived. The cell diameter, its wall thickness, and material strength are related to the impact resistance of the structure. With a decrease in the cell diameter and an increase in its wall thickness and material strength, the energy absorption rate of the composite structure is gradually enhanced. Among the 44 composite groups, the structure with the cell diameter of D = 3 mm, the wall thickness of 0.08 mm, and 4340 steel possessed the best energy absorption effect, the energy absorption rate is 54.7% more than for the cell diameter of D = 6 mm and 2024 aluminum. The honeycomb structure composed of various cell diameters has little difference, but it exerts a certain effect on the cell diameter.

CO2 capture technologies based on chemisorption present the potential to lower net emissions of CO2 into the atmosphere. The electrochemical upgrade of captured CO2 to value-added products would be particularly convenient. Here we find that this goal is curtailed when the adduct of the capture molecule with CO2 fails to place the CO2 sufficiently close to the site of the heterogeneous reaction. We investigate tailoring the electrochemical double layer to achieve the valorization of chemisorbed CO2 in an aqueous monoethanolamine electrolyte. We reveal, using electrochemical studies and in situ surface-enhanced Raman spectroscopy, that a smaller double layer distance correlates with improved activity for CO2 to CO from amine solutions. With the aid of an alkali cation and accelerated mass transport by system design—temperature and concentration—we demonstrate amine–CO2 conversion to CO with 72% Faradaic efficiency at 50 mA cm–2. Electrochemical conversion of CO2 into high-value products is attractive for lowering net carbon emissions. Lee et al. present the valorization of chemisorbed CO2 to CO in an aqueous monoethanolamine electrolyte via tailoring of the electrochemical double layer, with 72% Faradaic efficiency at 50 mA cm–2.

Electrophoresis of a soft particle with a charged polarizable core is analyzed theoretically. The soft particle is embedded in an uncharged hydrogel medium. The hydrodynamics in both the gel medium and the soft layer encapsulating the hard core are governed by the Darcy-Brinkman model. We have considered the numerical model based on the conservation principle of mass, momentum, and ion flux, leading to a coupled set of partial differential equations. A simplified approach under the weak field and low charge density consideration is also proposed. The subtle nonlinear effects arising due to the polarization and relaxation of the double layer and the convective transport of counterions induced by the immobile charge of soft layer are elucidated. These nonlinear effects have negligible impact when the bulk ionic concentration becomes high. The simplified model under the weak field consideration is independent of the core dielectric permittivity. However, the numerical model shows a strong dependence on core permittivity when the applied electric field is moderate. We have also addressed the ion partitioning effect when the dielectric permittivity of the soft layer is different from the gel medium. This creates a counterion saturation in the soft layer, and hence an augmentation in the electrophoresis.

To improve the ablation resistance of carbon/carbon (C/C) composites, a SiC/ZrC-ZrB2 double layer coating was fabricated by pack cementation and slurry-sintering method. The ablation resistance of the SiC/ZrC-ZrB2 coating was tested under plasma flame above 2300 °C. The results indicate that the SiC/ZrC-ZrB2 double layer coating exhibits superior ablation resistance than the ZrC-ZrB2 single layer coating. After being ablated under the plasma flame for 20 s, the mass and linear ablation rates of the ZrC-ZrB2 coating are 0.89 mg/s and 15.3 µm/s, while those for SiC/ZrC-ZrB2 coating are 0.09 mg/s and 24.15 µm/s, respectively. During ablation, the SiC inner layer can generate SiO2 glass and result in the formation of ZrO2-SiO2 molten film. Compared with the ZrO2 molten film formed on the ZrC-ZrB2 coating surface, the ZrO2-SiO2 molten film with lower oxygen diffusion rate and viscosity enables the SiC/ZrC-ZrB2 coating to have better self-healing ability. Therefore, the enhanced ablation resistance of the SiC/ZrC-ZrB2 coating can be attributed to the formation of dense ZrO2-SiO2 molten film under the plasma flame.

Relevant fundamentals of the electrochemical double layer and supercapacitors utilizing the interfacial capacitance as well as superficial redox processes at the electrode/solution interface are briefly reviewed. Experimental methods for the determination of the capacity of electrochemical double layers, of charge storage electrode materials for supercapacitors, and of supercapacitors are discussed and compared. Intrinsic limitations and pitfalls are indicated; popular errors, misconceptions, and mistakes are evaluated. The suitability of available methods is discussed, and practical recommendations are provided.

The operation of dye-sensitized solar cells and quantum dot-sensitized solar cells (QDSSCs) depends strongly on the photoanode material employed. This is addressed in the present work by developing photoanodes based on a double-layer TiO2 inverse opal material with different interconnected pore sizes in the bottom and upper layers for use in QDSSCs. The proposed photoanode material leads to better infiltration of the sensitizers and the hole transporting material through the entire depth of the TiO2 layer. Double-layer TiO2 inverse opal-based QDSSCs are demonstrated to facilitate the greater absorbance of quantum dots and obtain higher photocurrent and power conversion efficiency than QDSSCs adopting single-layer TiO2 inverse opal photoanodes. Various QDSSCs employing double-layer TiO2 inverse opal photoanodes with different pore sizes in the layers are tested. The CdS/CdSe co-sensitized solar cell adopting the optimum photoanode configuration and thickness provided the highest QDSSC conversion efficiency of 5.79%.

The local structure of cellulose, dissolved in the frequently used ionic liquid EMIm-OAc, is modelled by a coaxial double layer cylinder. The cylinder’s core consists of a cellulose chain while the sheath is formed by a solvent layer with lower electron density than the bulk solvent. We studied 2% cellulose solutions in EMIm-OAc and their behavior upon addition of increasing amounts of water. At this cellulose concentration, 15 wt% of water induced the precipitation of cellulose. Water molecules did not form an independent phase, but were bound to EMIm-OAc in the cellulose/water/EMIm-OAc solution. The conformational of a cellulose chain changes by adding water into the solution, and the square of the apparent cross-sectional radius of gyration of the cellulose chain becomes zero to negative. This phenomenon is explained by the formation of a solvation shell with lower electron density than the bulk solvent around the cellulose chain.

By combining the advantages of sheet hydroforming and multi-layer sheet deep drawing in wrinkling suppression, double-layer sheets hydroforming process was proposed. Different from the multi-layer sheet deep drawing, the two sheets are not bonded together, the upper sheet is introduced to eliminate the wrinkling defects occurred in the formed lower sheet. Therefore, how to determine the appropriate upper sheet is the key point in this process. Based on this, some investigations in selecting the appropriate upper sheet have been down, but the selection principle for the appropriate upper sheet is still ambiguous. To make clear this, in this paper, a semi-ellipsoid curved sheet part made of 2198 Al-Li alloy with an axial length ratio of 0.9 was chosen as the target part, by changing the thickness of the upper sheet (5A06-O aluminum alloy); the primary and secondary order of the anti-wrinkle ability and interfacial friction stress in suppressing the wrinkle defects were investigated and the selection principle for appropriate upper sheet is obtained.

Analysis of electrostatic floating potential fluctuations associated with multiple anodic double layer revealed a complexity dynamic coexisting with chaotic behavior. These externally controllable nonequilibrium quasi-stationary multiple anodic double layers were created in a cold cathode dc discharge setup in front of an extra anode which was used to supplement additional ionization. Despite the fact that chaos and complexity dynamics are often defined with entirely different properties, this study provides scenarios under which both can exist simultaneously. A stable multiple double-layer structure consisting of four successive double layers, each with positive and negative charged particles arranged in opposite sheets, was created when the anode potential exceeds a certain threshold value for a minimum gas breakdown bias between cathode and ground. After the stable multiple double layers was created, it was further controlled externally by varying the cathode bias between minimum gas breakdown bias of − 335 V and − 610 V at a pressure of 0.3 mbar for studying its advanced stages. With increase in cathode bias, multiple anodic double-layer structure advances towards the anode surface with the collapse of innermost layer due to the arrival of more energetic electrons in the anode zone. This process results from the self-organization and re-organization of charged particles in each double layer mediated by energetic electrons. The process continued until all the double layers disappeared and only an intense anode glow remained at anode for higher values of cathode bias. The chaotic dynamics of the system was studied at every stage by analyzing the corresponding floating potential fluctuations using FFT, phase space trajectories and nonlinear technique such as Lyapunov exponent, time-delay reconstruction etc. The analysis revealed the onset of chaos beyond − 410 V was triggered by the collapse of double layers. Estimation of correlation dimension, autocorrelation function and Hurst exponent unfolded the complexity features such as self-similarity and longtime dependence in the fluctuations. The value of correlation dimension reaches the maximum with an increase in cathode bias. Estimation of Hurst exponent using rescaled range analysis technique with values of H between 0.5 and 1 and algebraic decay of autocorrelation function provide signatures of long-range temporal correlations in the chaotic fluctuations and underlines the coexistence of complexity behavior.

Ion acoustic double layers in a multicomponent plasma consisting of positive ions, negative ions, and nonthermal electrons filled in a cylindrical waveguide have been theoretically investigated using pseudopotential technique. The expression of Sagdeev potential for the ion acoustic wave in such a plasma has been derived, and the conditions for the existence of double layers are obtained. The effects of the boundary of cylindrical waveguide and nonthermal electrons on the Sagdeev potential have been graphically discussed. From the nonlinear equation, the solution for double layers of small amplitude ion acoustic waves is obtained, and the structure of double layers is analyzed as function of the plasma parameters. It is seen that finite geometry of bounded plasma, nonthermality of electrons, density of negative ions, and stream velocity of positive and negative ions have significant contribution on the structure of double layers. The double layers may be compressive or rarefactive in plasma depending upon the values of the plasma parameters.

The vision-based smart driving technologies to increase road safety are the popular research topics for modern automobile industries. The development of precise moving object detection with continuously tracking capability is the most important technology for such purpose nowadays. In this paper, we propose an improved object detection system, which combines a selected object detector with its enhancements and long short term memory (LSTM) modules, to improve the detection performance for smart driving systems. First, from a selected object detector, we combine all vehicle classes and bypassing low-level features to improve its detection performance. After the spatial association of the detected objects, the outputs of the improved objector are then fed into the proposed double-layer LSTM (dLSTM) modules to successfully improve the detection of the vehicles in various conditions, including the newly-appeared, the detected and the gradually-disappearing vehicles. With stage-by-stage evaluations, the experimental results show that the proposed vehicle detection system with the improved procedures and dLSTM modules can precisely detect the vehicles without increasing computations.

We propose a novel method to fabricate small apertures in a metal film using polymethyl methacrylate (PMMA). A PMMA/SiO2 double layer is employed to perform a negative tone lift-off with SiO2 as a sacrificial layer. Through this method, we succeeded in making sub-50 nm holes in a metal film using well-established individual fabrication steps. The proposed method will be more reliable and economical compared to the hydrogen silsesquioxane/PMMA bilayer method.

A photoresponsive double-layer hydrogel has been developed, in which light-sensitive cinnamic moieties are grafted onto a polyacrylamide network to produce a photoresponsive layer and pure polyacrylamide formed the supporting layer. Ag nanoparticles were dispersed using in situ reduction on the photoresponsive layer to act as the catalyst. The as-fabricated hydrogel exhibits a shape memory effect and controllable catalytic behavior under an external light stimulus. When exposed to ultraviolet (UV) light at λ > 260 nm, the resulting cycloaddition of cinnamic moieties not only fix the hydrogel’s temporary shape, but also greatly slow down the catalytic reaction rate. After irradiated with UV light at λ < 260 nm, however, the newly formed crosslinking points are reversibly cleaved. This results in the shape recovery of the hydrogel to its permanent shape. At the same time, the catalytic reaction was greatly accelerated because of the facile diffusion of the reactants into the hydrogel.

The adsorption of three different polycations at the negatively charged surface of tubular J-aggregates of the amphiphilic cyanine dye 3,3′-bis(2-sulfopropyl)-5,5′,6,6′-tetrachloro-1,1′-dioctylbenzimidacarbocyanine (C8S3) is investigated by means of cryogenic electron microscopy and optical absorption spectroscopy. All three polycations could be adsorbed at the tubular aggregates without flocculation or precipitation when added in molar amounts of monomers sufficiently smaller than that of the dye molecules. It is found that preferably, a minority of aggregates is coated by the polycations while a majority of aggregates is left uncoated. For the coated aggregates, the adsorption leads to charge reversal of the aggregate surface as supported by zeta potential measurements. The morphology of the coating differs significantly for the three polycations: The branched polycation polyethylenimine (PEI) attaches to the tubular aggregate by hit-and-stick adsorption of the coiled state in solution forming irregular clot-like coatings; the flexible and weakly cationic poly (allylamine hydrochloride) (PAH) forms a more homogeneous coating but destroys the integrity of the dye aggregate; the more hydrophobic and strong polycation poly (diallyldimethylammonium chloride) (PDADMAC) forms a thin and homogeneous layer, supposedly by wrapping around the tubular aggregate. For the latter growth of a second double layer of dyes is observed for the aggregates. The different morphologies of the coating layers are explained by the details of the chemical structure of the polycations. The possible adsorption of polyelectrolytes at these amphiphilic tubular structures, stabilized by means of hydrophobic forces, is far from obvious and demonstrates an applicable route to the build-up of more complex nanostructures in solution by means of a self-assembly process.

Although cellulose is the oldest macromolecule we have known, its intrinsic properties are still not well understood because of the lack of suitable solvents. The recent development of ionic liquids enables preparation of cellulose solutions in which cellulose molecules are supposed to be dispersed molecularly. Conventionally a semi-flexible-chain model or a worm-like chain model has been applied to describe the dilute solution properties of cellulose. A semi-flexible chain model is specified in terms of a persistent length to determine the chain stiffness of a solute molecule, completely neglecting details of the solvent–solute interaction, and the discussion is mainly focusing on the conformation of a solute molecule. In this paper we adapt a cylinder model which at least specifies the local shape of a solute molecule. Since the ionic liquids are now available as a new solvent of cellulose, we have prepared cellulose/ionic liquid solutions for small-angle X-ray scattering (SAXS) measurements which provide information on the local structure of cellulose molecules in the restricted range. The SAXS measurements were performed on the cellulose/ionic liquid solutions at two independent synchrotron facilities and confirmed the consistency of the observed scattering profile. Standard methods were applied to analyze the scattered data first, and afforded a model for representing a cellulose molecule in ionic liquid solutions. Two types of ionic liquids were used, and it was ascertained that cellulose was not degraded under the conditions used. The solution characteristic was found to change by heating during the preparation of each solution. The heating effect on the conformational change of cellulose was discussed in terms of the solute–solvent interaction from the simulation with a coaxial double layer cylinder model. The state of solvent packing was considered as well from the thickness and relative electron density of the sheath in the simulated coaxial double layer cylinder model.

In the present research paper, propagation attributes of nonlinear electron-acoustic (EA) waves have been investigated in an unmagnetised plasma system consisting of cool fluid electrons and hot electrons observing the hybrid Cairns–Tsallis distribution. Sagdeev pseudopotential method has been used to explore the occurrence of large-amplitude solitons and double layers, focussing on how their characteristics depend upon different parameters. The analysis is further extended to examine the dynamics of large- and small-amplitude double layers. It is revealed that the present plasma system supports the existence of negative potential solitons and double layers in certain region of parameter space. The numerical results show that the Cairns–Tsallis-distributed hot electrons may affect the spatial profiles of EA waves and double layers. The present investigation may be relevant to the observation from Viking satellite in the dayside auroral zone.

Laser-driven ion sources are interesting for many potential applications, from nuclear medicine to material science. A promising strategy to enhance both ion energy and number is given by Double-Layer Targets (DLTs), i.e. micrometric foils coated by a near-critical density layer. Optimization of DLT parameters for a given laser setup requires a deep and thorough understanding of the physics at play. In this work, we investigate the acceleration process with DLTs by combining analytical modeling of pulse propagation and hot electron generation together with Particle-In-Cell (PIC) simulations in two and three dimensions. Model results and predictions are confirmed by PIC simulations—which also provide numerical values to the free model parameters—and compared to experimental findings from the literature. Finally, we analytically find the optimal values for near-critical layer thickness and density as a function of laser parameters; this result should provide useful insights for the design of experiments involving DLTs. Laser-driven ion acceleration is an important topic for next-generation compact accelerators and material characterisation. The authors present a theoretical study on ion acceleration with near-critical double-layer targets that supports the experimental realisation of these targets and the interpretation of experiments of laser-ion acceleration.

By using Monte Carlo simulations, we investigated a triangle double-layer graphene nanoisland with mixed-spin (3/2, 2) configuration. We focused on the effects of crystal-fields, exchange couplings, longitudinal magnetic fields, and temperature on the magnetic properties of the system. Various curves of magnetization, susceptibility, and internal energy as a function of temperature were obtained. We plotted the phase diagrams of blocking temperature in the different parameter planes. We found that increasing |Jab/JZ|,Jbb/JZ, and h/JZ or weakening |Db/JZ| is beneficial to improving the TB/JZ, but the TB/JZ is very insensitive to changes in the Da/JZ and Jaa/JZ. In addition, it is worth noting that the system can exhibit abundant multiple-loops hysteresis behaviors for certain physical parameters, such as triple, quadruple, quintuple, septuple hysteresis loops.

Expressions are derived for the force and energy of the double-layer interaction between two parallel similar plates with arbitrary surface charge densities or surface potentials at arbitrary separations in an electrolyte solution, by taking into account the finite ion size effect on the basis of the full expression of the activity coefficients of electrolyte ions derived by Carnahan and Starling. The results for two models of the double-layer interaction, that is, the constant surface potential and constant surface charge density models, are given. It is shown that in the constant surface potential model, at large plate separations, the magnitudes of the double-layer interaction force and energy increase as the total ion volume fraction increases but this tendency reverses at small plate separations, while in the constant surface charge density model, they always increase as the total ion volume fraction increases.

Herein, we evaluated the quality of a double-layer coating method to stably immobilize photocatalysts by photodecomposition of dimethyl sulfoxide (DMSO) on a stainless-steel wire mesh using a flow analytical system, which included the reactor and conductimetric detector (FAS-CD). The prepared photocatalyst consisted of an amorphous titanium peroxide sol layer and a layer of a sol mixture containing TiO2 and amorphous titanium peroxide. Stable photocatalytic activity was demonstrated through successive photodecomposition tests of DMSO using FAS-CD/equipment.

The existence of a dust ion acoustic double layer in a collisionless, un-magnetized, multi-component plasma is reported here. The plasma model consists of ions, negatively charged dust particles and two components of superthermal electrons. By following Sagdeev potential and reductive perturbation method, the electrostatic double layer of negative polarity is shown to exist in small-amplitude regime. From the analytical study, it is observed that the amplitude of the double layer depends upon various parameters of the superthermal electrons as well as on the dust concentration. The model considered here has a good match with the data obtained from Cassini spacecraft for outer magnetosphere of Saturn (~ 14 Rs, Rs being the radius of Saturn). So, the results obtained from this study are useful for understanding the nature of the plasma waves in Saturn magnetosphere .

In the hydroforming of curved sheet parts with a small thickness-diameter ratio, qualified parts are difficult to be manufactured when using the traditional hydroforming process. To solve this problem, double-layer sheet hydroforming was proposed and the wrinkle-free sheet parts were obtained in the authors’ previous study, but the inhibition mechanism of forming defects is far from perfection. Therefore, in this paper, the inhibition mechanism of forming defects is investigated by the combination of FE simulations and technological experiments. Different from the previous research, 2198 Al-Li alloy sheet was selected as the lower sheet. Other conditions such as heat treatment status and thickness are the same as before. The principle of wrinkle elimination can be concluded into the following two aspects. On the one hand, the upper sheet cannot be wrinkled during hydroforming, On the other hand, the surface blank holder pressure is applied in the suspending area. In addition, the beneficial friction between this two sheets changes the radial stress state of the lower sheet and makes the radial strain at some specific area (punch contact area and die corner area) decreased. In conclusion, qualified sheet parts can be manufactured by double-layer sheet hydroforming.

An extreme sea storm process can lead to a jack-up rig under the combined loading condition of vertical load (V), horizontal load (H), and moment (M) to have stability problems. This paper presents the analysis of combined bearing capacities of a circular spudcan on layered clays with a strong layer overlying a comparatively weaker layer. Numerical models combined with displacement- based load tests, swipe tests, and constant ratio displacement probe tests are adopted to calculate the uniaxial bearing capacities, failure envelopes in combined V-H, V-M planes, and failure envelopes in a combined V-H-M load space, respectively. A parametric study on the effects of vertical load level V, the layer strength ratio su,t/su,b, and the hard layer thickness t1 on the bearing capacities is then performed. Results show that the vertical load level is a key factor that influences the values of H and M and the size of the H-M failure envelope. The existence of the underlying weak clay decreases the bearing capacities in all directions, and the vertical capacity Vult is affected more than the horizontal (Hult) and moment (Mult) capacities based on a single uniform deposit. The influence of the underlying weak clay on H-M failure envelope is mainly shown where H and M are coupled in the same direction. In contrast, little difference is observed when H and M are coupled in opposite directions.

In this paper, we reported the design and preparation of a double-layer antireflective (AR) coating, which possessed relatively high transmittance at 351, 527, and 1053 nm. The refractive indices and film thicknesses of the under layer and upper layer of the simulated AR coating were determined as 1.27, 95 nm and 1.18, 106 nm, respectively. The under layer of the double-layer coating dip-coated from a mixture of base-catalyzed and acid-catalyzed silica sols had a refractive index of 1.27. The upper layer fabricated by the deposition of methylated silica nanoparticles by simply adding methyltriethoxysilane into the base-catalyzed silica sols possessed a refractive index of 1.18. The hydrophobicity of coatings could be dramatically improved with the water contact angle increasing from 23.4° to 150.0°, and the refractive indices of the pure base-catalyzed silica coatings were easily decreased from 1.20 to 1.12 through the surface treatment of silica nanoparticles. Thus, we have successfully prepared a double-layer AR coating, which had a high transmittance of 99.8%, 96.1%, and 99.7% at 351, 527, and 1053 nm, respectively.

Possessing the unique and highly valuable properties, graphene sheets (GSs) have attracted increasing attention including that from the building engineer due to the fact that Graphene can be utilized to reinforce concrete and other building materials. In this work, the nonlocal elastic theory and classical plate theory (CLPT) are used to derive the governing equations. The element-free framework for analyzing the buckling behaviors of double layer circular graphene sheets (DLCGSs) relying on an elastic medium is proposed. Pasternak-type model is adopted to describe the elastic medium. Accordingly, the influences of boundary conditions, size of GSs and nonlocal parameters on the buckling behavior of DLCGSs are investigated. The results show that the OP buckling modes are only sensible to the van der Waals forces.

Here, the interfacial synergism of discontinuous spot shaped SnO2 and TiO2 mesoporous nanocomposite as electron transfer layer (ETL) underlayer is presented in highly efficient mesoscopic perovskite solar cells (M-PSCs). Based on this new strategy, strong charge recombination observed in previous SnO2-based ETLs is suppressed to a great extent as the pathways of charge recombination and energy loss are blocked effectively. Meanwhile, the internal series resistance of entire M-PSC is decreased remarkably. The new ETL is more kinetically favorable to electron transfer and thus results in significant photovoltaic improvement and alleviated hysteresis effect of M-PSCs.

Ni/Al laminates are of great interest in many aerospace and military applications due to their excellent mechanical properties. However, their application has been limited in part due to challenges related to fabricating complex geometries. However, explosive welding is regarded as a promising technique to fabricate laminates. However, it is difficult to fabricate Ni/Al/Ni laminates with high interfacial shear strength and ductility if the stand-off distance has not been optimized during the explosion process. The goal of this study was to investigate the effect of stand-off distance on the microstructure and mechanical properties of Ni/Al/Ni laminates, and SEM and EDS were used to characterize the morphology and element distribution of the double layer interface. Tensile and tensile-shear tests were conducted to evaluate the mechanical properties of the laminates. The results indicated that with the increase in stand-off distance, three different kinds of interface were obtained (straight, wavy and continuously melted). Thickness of atomic diffusion layer increased with the increase in stand-off distance. Moreover, the Ni/Al/Ni laminates with wavy interface possessed highest value of ductility and interfacial bonding strength.

The effects of supporting electrolyte on the kinetics of the elementary step of electron transfer are considered as unavoidable interplay of interfacial phenomena and ionic equilibria in solution. For the former, the problems to separate contributions of electrostatic electrode-reactant interactions and specific adsorption are addressed, and various aspects of the traditional Frumkin correction (“psi-prime effect”) are discussed. The construction of corrected Tafel plots is shown to be a procedure containing the internal contradiction resulting in an uncertainty. This uncertainty can be eliminated by combining the principles of traditional analysis of the “double layer” effects with physical theory instead of phenomenological approaches. Specific manifestations of parallel electron transfer to an ensemble of reacting species are presented in the context of “mean reactant charge in solution bulk.” The approach to account for non-spherical shape and inhomogeneous charge distribution in reacting species is considered in terms of “molecular psi-prime effect.” Finally, some comments are given on analogy of “double layer” effects at metal/solution interface and interfacial phenomena specific for more complex and highly relevant electrochemical systems.

The double-layer vanadium dioxide (VO2) thin film patterned by SiO2 spheres has been fabricated to enhance luminous transmittance (Tlum) without severely expense of solar modulation ability (ΔTsol) for the thermochromic smart windows. The first layer of vanadium thin film was deposited on the substrate with self-assembly SiO2 spheres and then the SiO2 spheres was removed by ultrasonic oscillation. The orderly perforated vanadium thin film with regular pores formed. Afterwards, the second layer of vanadium thin film was deposited on the perforated vanadium thin film. The semi-perforated double layer of vanadium thin film formed and was rapid thermal annealed forming the semi-perforated double VO2 thin films. Compared with continuous VO2 thin film(Tlum, 8.8%, ΔTsol, 5.9%), the semi-perforated double VO2 layer possesses orderly-patterned crater, which facilitate Tlum (42.6%) and only slightly attenuate the ΔTsol (5.5%). The phase transition temperatures for continuous VO2 thin film and the optimized semi-perforated VO2 double layer thin film were 58 °C and 52 °C, respectively, far below 68 °C of bulky VO2. This structure should be very meaningful for the real application of VO2-based smart window in the future.

We demonstrated a simple method of fabricating large-area, few-layer graphene that involves performing femtosecond pulsed laser deposition at a relatively low temperature of 500 °C and a high pressure of 10 $$^{-5}$$ Torr using a double-layer Ni catalyst. The average thickness of the resulting graphene films was less than 3 nm, their average area was more than 1 cm $$^{2}$$ , and their electrical resistivity was only 0.44 $${\rm m}\Omega .{\rm cm}$$ . The laser deposition process was also conducted at different laser energies, and it was observed that the quality of the few-layer graphene could be improved using a double-layer catalyst at a higher laser energy. The ejection of C clusters by breaking the C–C bonds of the HOPG through multi-photon ionization can explain the observed graphene formation characteristics. The insights may facilitate the controllable synthesis of large-area, mono-layer graphene and promote the commercialize application of the graphene.

A novel and green electrochemical immunosensor for detection of Staphylococcal enterotoxin Q (SEQ), a toxic superantigen that can induce severe food poisoning and even fatal conditions, was developed by fixing double-layer gold nanoparticles (AuNPs), horseradish peroxidase, and thionin-chitosan composite membrane on the glassy carbon electrode surface. Under optimal conditions, the developed immunosensor showed a wide linear range from 0.1 to 100 pg mL−1 (R 2 = 0.992) for SEQ with a low detection limit of 0.046 pg mL−1 (S/N = 3). The immunosensor had good specificity (no significant cross reaction with lipopolysaccharides, bovine IgG, Escherichia coli, or other common biological components), and remained fairly stable (over 87 % of the original signal response after stored for 20 days at 4 °C). In addition, the immunosensor was successfully applied to milk sample detection and demonstrated with high recoveries (from 91 to 113 %). In conclusion, the developed electrochemical immunosensor can supply a green and feasible tool for detection of SEQ in food.

Guanine plays an important role in many biological processes since it constitutes the buildings blocks of DNA and RNA. Solutions of guanine were prepared to cover the range from 5 × 10−5 to 8 × 10−4 M. Adsorption of guanine on a mercury electrode in acetic buffers at pH 4 and pH 6 is described by means of the adsorption isotherms constants calculated from the surface pressure as a function of electrode potential and adsorbate bulk concentration. The adsorption parameters from the double layer were calculated based on the data from the differential capacity–potential curves. The entirely different change in the differential capacity in two applied acetate buffers in the absence of guanine results from different buffer composition, as in a solution with a pH 4 adsorption primarily involves acetic acid molecules, whereas in a buffer with a pH 6-acetate ions. The possibility to accurately determine E max and σ max parameters points to a physical character of guanine adsorption, which must be associated with the fact that adsorbed guanine molecules are vertically or diagonal oriented. Obtained R A (charge transfer resistance at formal potential) changes are minor and comply with changes in ΔE. Therefore, it may be concluded that in the tested range of guanine concentrations, it has no effect on kinetics of zinc cation depolarisation at a mercury electrode both in the buffer with pH 4 and pH 6.

Conjugated polymer P, which was synthesized by introducing 9,9-diphenylfluorene and thiophene units into the backbone of poly(fluorenylene ethynylene), showed high sensitivity in detecting nitroaromatics. A double-layer sensor, named P-PS/GEL, was prepared by electrospinning technique using polymer P, polystyrene (PS), and gelatin (GEL). A nanofibrous membrane from the mixture of PS and P as the top layer (P-PS) served as the sensing layer for detecting nitroaromatics (NACs). A gelatin nanofibrous membrane as the bottom layer (GEL) served as porous scaffold for the top layer. Therefore, apart from transferring into the top layer directly from above, the NACs molecules could also approach the top sensing layer through the bottom porous layer. This double-layer conformation greatly improved the permeability of the P-PS layer. As a result, the double-layer sensor exhibited a greater quenching efficiency (Q f) of 75 % than that of the single-layer P-PS (55 %). Importantly, the sensor showed good reversibility of quenching process after being exposed to saturated DNT vapor for 6 cycles.

In this article, the wrinkling behavior and thickness distribution of 5A06 aluminum alloy sheets in an annealed state with thickness of 1.0 mm and 2.5 mm was numerically and experimentally investigated under different hydraulic pressures in the hydroforming of single-layer and double-layer sheets. Note that, in double-layer sheets hydroforming, an upper-aided sheet is needed. The upper, thicker sheet synchronously deforms with the lower, thinner sheet during hydroforming. When the double-layer sheets are separated, a thinner curved sheet part will be manufactured. As can be seen from the simulation and experimental results, the upper, thicker sheet could effectively suppress the wrinkles of the lower, thinner sheet and improve the thickness distribution due to the increasing anti-wrinkle ability of the formed sheet and the interfacial friction between the double-layer sheets. In addition, the maximum hydraulic pressure can be decreased via hydroforming of double-layer sheets; this approach reduces the drawing force for large sheet parts and meets the requirement of energy conservation.

Based on the interplay between propagating surface plasmon polaritons (PSPs) in graphene ribbon and double layer sheets structure, we theoretically demonstrate a tunable strong coupling mechanism significantly different from reported conventional noble metal nanostructures. The strong electromagnetic coupling between the low order antisymmetric and high order symmetric PSPs modes occurs due to the intersections of dispersion curves, which leads to a modification of plasmonic dispersion and multiple significant anti-crossing regions. Of particular, this strong coupling is controllable through external gate voltage of graphene sheets or ribbon. The results offer an effective regime to dynamically tune the interaction of graphene PSPs, which may find applications in the field of nanophotonic devices in the mid-infrared range.

We have prepared three kinds of graphene heat dissipation film as non-continuous single layer single-crystal graphene (NCSG), continuous single layer graphene (CSG) and continuous double layer graphene (CDG). Then graphene was transferred on 2-inches SiO2/Si substrate as heat dissipation film. Temperature field distribution was tested by infrared camera, and thermal conductivity of composite interface of heat dissipation film on SiO2/Si was studied using Fourier’s law. When supply voltage was 10 V, NCSG film made the center temperature dropped by 1 °C, and CSG made the central temperature dropped by 6 °C and the thermal conductivity of CSG on SiO2/Si was increased by 15.7 %. For CSG on SiO2/Si, with the increased of supply voltage, the center temperature drop was increased, but the improvement of thermal conductivity was decreased.

Hydrophilic silica nanoparticles alone are not surface active. They, however, develop a strong electrostatic interaction with ionic surfactants and consequently affect their surface behavior. We report the interfacial behavior of n-heptane/anionic-surfactant-solutions in the presence of hydrophilic silica nanoparticles. The surfactants are sodium dodecyl sulfate (SDS) and dodecyl benzene sulfonic acid (DBSA), and the diameters of the used particles are 9 and 30 nm. Using experimental tensiometry, we show that nanoparticles retain their non-surface-active nature in the presence of surfactants and the surface activity of surfactant directly increases with the concentration of nanoparticles. This fact was attributed to the electrostatic repulsive interaction between the negatively charged nanoparticles and the anionic surfactant molecules. The role of electrostatic repulsion on increasing surface activity of the surfactant has been discussed. Further investigations have been performed for screening the double layer charge of the nanoparticles in the presence of salt. Moreover, the hydrolysis of SDS molecules in the presence of silica nanoparticles and the interaction of nanoparticles with SDS inherent impurities have been studied. According to our experimental observations, silica nanoparticles alleviate the effects of dodecanol, formed by SDS hydrolysis, on the interfacial properties of SDS solution.

The swelling behavior of a Na+-bentonite used in geosynthetic clay liners with lower dry unit weights (less than about 11 kN/m3) was investigated experimentally, and analyzed by diffuse double layer (DDL) theory. Four types of liquid were used. It has been found that the measured swelling pressures are about 20% of that predicted by DDL theory. There are linear relationships between the calculated double layer thickness and the measured corresponding free swelling index and liquid limit.

In this work, a thermopile-based MEMS IR sensor is reported. In the device, a double-layer thermocouple strip structure and thermal-conductive-electrical-isolated structures are adopted thus to reduce the size and to improve performance of the whole device. After being packed into a TO-5 package, the sensor achieves a responsivity of 1151.14 V/W, a detectivity of 4.15 × 108 cm Hz1/2/W, and a response time of 14.46 ms. Besides, in measurements of varied temperatures and vacuum pressures, the thermopile proposed in this work could reach relatively high sensitivities. This indicates that such a device can also function as a temperature sensor and a vacuum sensor. In this way, the applications of thermopiles are broadened.

The present paper deals with the propagation of Love-type wave in an initially stressed irregular vertically heterogeneous layer lying over an initially stressed isotropic layer and an initially stressed isotropic half-space. Two different types of irregularities, viz., rectangular and parabolic, are considered at the interface of uppermost initially stressed heterogeneous layer and intermediate initially stressed isotropic layer. Dispersion equations are obtained in closed form for both cases of irregularities, distinctly. The effect of size and shape of irregularity, horizontal compressive initial stress, horizontal tensile initial stress, heterogeneity of the uppermost layer and width ratio of the layers on phase velocity of Love-type wave are the major highlights of the study. Comparative study has been made to identify the effects of different shapes of irregularity, presence of heterogeneity and initial stresses. Numerical computations have been carried out and depicted by means of graphs for the present study.

Hierarchical TiO2 flower-spheres assembled from porous nanosheets-stacked of nanoparticles were synthesized by a simple hydrothermal method with one-step. The as-prepared TiO2 flower-spheres showed a diameter range from 200 nm to 550 nm and a large surface area of 188 m2/g. A double layer photoanode made of P25 nanoparticles and as-prepared TiO2 flower-spheres was fabricated for the dye sensitized solar cells(DSSCs). The efficient light scattering and dye absorption of the photoanode can be attributed to the top-layer of hierarchical TiO2 flower-spheres. DSSCs based on the double layers photoanode exhibit a higher energy conversion efficiency of 8.11% with a short-circuit photocurrent density of 17.87 mA/cm2, indicating that there is an increase of 38% in the conversion efficiency compared to those based on electrode P25(5.91%, 14.09 mA/cm2).