Selective Surface Research Articles

Efficacy of Alexandrite Laser in the Treatment of Pigmented Actinic Keratoses: A Pivotal Study.

Pigmented actinic keratoses (PAKs), a pigmented variant of actinic keratosis, present diagnostic challenges due to their resemblance to both benign and malignant lesions. Conventional therapies have inconsistent outcomes and may cause undesirable side effects. This study investigates the efficacy of the Alexandrite laser, a pulsed laser with selective melanin absorption, for PAK treatment. Through dermoscopic analysis pretreatment, it aims to identify predictive patterns for better treatment outcomes. Patients with PAKs were enrolled in a multicenter study, receiving standardized Alexandrite laser therapy. Detailed dermoscopic evaluations were conducted pretreatment. The Physician's Global Assessment (PGA) and Target Lesion Pigmentation (TLP) scales measured treatment efficacy. The study included 50 patients with 60 PAKs. Following treatment, there was a statistically significant reduction in TLP scores, particularly in lesions with pigmented pseudo-networks and gray-brownish dots, which were linked to improved outcomes. No adverse effects were reported, suggesting the safety and tolerability of the laser treatment. The Alexandrite laser emerges as a promising modality for the management of PAK pigmentation, with specific dermoscopic patterns being indicative of a favorable response. This study reinforces the critical importance of dermoscopic expertise in the selection and optimization of treatment for PAKs. Future research should focus on comparative studies with different lasers or combination therapies to develop a more comprehensive treatment framework for PAKs.

Preparation and Utilization of a Highly Discriminative Absorbent Imprinted with Fetal Hemoglobin.

Development in hemoglobin-based oxygen carriers (HBOCs) that may be used as alternatives to donated blood requires an extensive supply of highly pure hemoglobin (Hb) preparations. Therefore, it is essential to fabricate inexpensive, stable and highly selective absorbents for Hb purification. Molecular imprinting is an attractive technology for preparing such materials for targeted molecular recognition and rapid separations. In this case study, we developed human fetal hemoglobin (HbF)-imprinted polymer beads through the fusion of surface imprinting and Pickering emulsion polymerization. HbF was firstly covalently coupled to silica nanoparticles through its surface-exposed amino groups. The particle-supported HbF molecules were subsequently employed as templates for the synthesis of molecularly imprinted polymers (MIPs) with high selectivity for Hb. After removing the silica support and HbF, the resulting MIPs underwent equilibrium and kinetic binding experiments with both adult Hb (HbA) and HbF. These surface-imprinted MIPs exhibited excellent selectivity for both HbA and HbF, facilitating the one-step isolation of recombinant Hb from crude biological samples. The saturation capacities of HbA and HbF were found to be 15.4 and 17.1 mg/g polymer, respectively. The present study opens new possibilities for designed resins for tailored protein purification, separation and analysis.

Cascaded Frequency Selective Surfaces with Matryoshka Geometry for Ultra-Wideband Bandwidth

The purpose of this paper is to present cascaded frequency selective surfaces (FSSs) with matryoshka geometry to increase the effective bandwidth. We carry out an analysis of the influence of the spacing between the surfaces on the FSSs frequency response. The application involves a two-layer cascaded FSS, one as a band-stop filter with a matryoshka geometry and the other as a band-pass filter with inverted or negative matryoshka geometry. With this framework, it is possible to extend an ultra-wideband (UWB) of a bandwidth up to 2 GHz in the 1.8 GHz to 3.8 GHz range with just two layers and an air gap of 12 mm, in addition to a bandwidth of 2 GHz to 3.2 GHz with a smaller 4 mm gap between layers.

Bioinspired Spectrally Selective Phase‐Change Composites for Enhanced Solar Thermal Energy Storage

AbstractIntegrating solar thermal conversion with phase change materials (PCMs) offers a promising pathway for continuous thermal energy generation with a zero‐carbon footprint. However, substantial infrared radiation losses at elevated temperatures often hinder the efficiency of such integrated systems. Inspired by the thermoregulation mechanisms of polar bears, this work introduces composite PCMs with spectrally selective absorption to enhance solar thermal energy storage efficiency. These composite phase change materials (CPCMs), featuring densely packed SiC ceramic grains with high porosity, exhibit a thermal conductivity of up to 14 W m−1 K−1 and an energy storage density of 195.1 kJ kg−1. The incorporation of nanoparticle‐coated foil induces a plasmonic effect that increases solar absorptivity to 90.57% and reduces infrared emissivity from 71.94% to 7.47%. Consequently, the solar thermal storage efficiency is significantly increased from 54.56% to 81.65% at 500 K, effectively addressing the challenges associated with high‐temperature solar thermal storage. Additionally, the low infrared emissivity of the c (PNC), combined with the inherent heat absorption properties of PCMs, enables infrared stealth functionality. These multifunctional CPCMs demonstrate considerable potential for advancing high‐temperature solar thermal storage technologies and other heat‐related applications.

Dispersion compensation design of high-density stacking RFSS absorbers for wideband applications

Abstract A dispersion compensation design absorber realized by high-density stacking resistive frequency selective surface (RFSS) is proposed for wideband applications. Firstly, the quantitative relationship between the equivalent impedance of RFSS and the permittivity of the effective media is constructed with the help of the transmission matrix method. The dispersion regulation of permittivity is achieved by changing the pattern and the square resistance of RFSS. In terms of absorber design, a uniform absorber with dispersion manipulation is developed as a precursor absorber. The uniform absorber has an absorption performance better than −8.5 dB above 2 GHz at normal incidence. The loss mechanism is analyzed in detail by electric field distribution and surface power loss density distribution, indicating that the uniform design cannot achieve thickness saving when extending to low frequency. Therefore, a dispersion compensation design absorber is proposed to extend −10 dB bandwidth to 1.64–28.8 GHz. Experiment results agree well with the simulation results, validating the analytic methods and design principles.

Conformal Frequency Selective Surfaces in Radome Design: A Mini Review

In aerospace engineering, radomes play an important role in protecting antenna systems from external interference and minimizing air resistance during flight. However, traditional radomes often fall short of providing the electromagnetic filtering and stealth capabilities important for modern aircraft applications. Conformal Frequency Selective Surfaces (FSS) radomes represent an evolutionary step beyond their conventional counterparts. These structures not only continue to protect antenna structures from environmental adversities, but also adapt seamlessly to non-planar surfaces. This adaptation is not only functional but also covers aerodynamic and aesthetic considerations, improving stealth capabilities and multi-band frequency operability, which are key factors for state-of-the-art communications and radar systems. However, design and implementation of conformal FSS radomes have some challenges. Considering that one of the authors has focused on such challenges for new generation air platforms, this study examines the contemporary advancements in conformal FSS radome technology, highlighting the latest research and breakthroughs. It covers latest findings on cutting-edge materials, design methodologies, simulation techniques for performance prediction, and the practical applications and advantages of these radomes. Building on a theoretical foundation of FSS and radome integration, the article discusses material and design innovations, simulation challenges, and practical implementations. It is hoped that this review will act as a bridge for knowledge sharing and a stimulant for continued research within the domain of conformal FSS radome technology

A closely spaced dual band polarization insensitive FSS for 5G applications

This study presents a novel single layer Frequency Selective Surface (FSS) for fifth generation (5G) applications with a polarization independent closely spaced dual band response. The proposed design consists of four split ring apertures etched on a square patch printed on a RT5880 dielectric substrate. The FSS has two stop-bands at 24.78 GHz and 28 GHz center frequencies with attenuations around 55 dB. The S21<−10 dB bandwidths (BW) of these bands are 14.48 % and 9.25 %, respectively and these closely spaced bands succeed 1.13 frequency ratio. It shows a stable frequency response for both TE and TM polarizations. Furthermore, the FSS represents a single layered and quite thin (thickness 0.042λl) structure with its unit cell size (0.70λl × 0.70λl, where λl is the free-space wavelength at lower frequency). The novelty of the presented FSS is not only achieving a small closely spaced band ratio in the mmWave band and exhibiting polarization insensitivity but also providing these features with a simple geometry and, uncomplicated single layer structure. The simulation results were confirmed by well accordant measurement results. All these results make the presented FSS a good candidate for 5G electromagnetic interference (EMI) shielding applications.

Selective-wavelength perfect infrared absorption in Ag@ZnO conical metamaterial structure

We present a new selective Metamaterial Perfect Absorber (MPA) consisting of zinc oxide embedded silver (Ag@ZnO), designed for applications in infrared stealth technology. The numerical simulation included a wide frequency range from 1 to 1000 THz and shows that the design MPA structure presented two absorption peaks at the desired wavelengths of 1.7 µm and 6.5 µm. The absorptivity of both peaks reached approximately 93.1% and 93.5%. The first peak at 1.7 µm decreases the scattering of IR laser beams from the surface of the MPA structure and also lowers the infrared tracks that could direct laser-guided devices to its specific target. On the other hand, the second peak reduces the surface heat wave. The suggested MPA (Ag@ZnO) structure is activated by a plane wave using a full wave vector and a broad frequency domain solution. In the framework of computer simulation technology (CST) Microwave Studio, uses both Finite-Difference-Time-Domain (FDTD) and Finite-Element-Method (FEM) techniques to predict the optical behavior of the proposed MPA structure. Both peaks achieved a high value of absorptivity due to the simultaneous excitation of the electric and magnetic dipole at resonance wavelength.

A High Gain and Compact CPW-fed UWB Antenna Based on a Novel Frequency Selective Surface with Angular Stability

A High Gain and Compact CPW-fed UWB Antenna Based on a Novel Frequency Selective Surface with Angular Stability

A study on the mechanisms and influencing factors of interfacial physicochemical interactions between asphalt and mineral aggregates based on multiscale evaluation methods

The elucidation of interfacial physicochemical mechanisms between asphalt and mineral aggregates is vital for comprehending the interface formation in asphalt mixtures and enhancing their performance. To this end, multiscale evaluation methods were used to investigate the mechanisms and influencing factors of interfacial physicochemical interactions between asphalt and mineral aggregates (IPIAMA). Initially, the dynamic shear rheometer (DSR) was used to measure the complex shear modulus (G*) of various asphalt mastics. Subsequently, the interface film thickness was calculated using G* in conjunction with the Hashin and Mori-Tanaka (MT) micromechanical models. This indicator facilitated quantitative assessments and the analysis of influencing factors. The results indicated that the MT model underestimated the interface film thickness by approximately 0.08–0.29 % compared to the Hashin model, a discrepancy attributable to assumptions regarding aggregate particle interlocking. Moreover, the interface film thickness systematically varied with factors such as aggregate content, type of aggregate, and type of asphalt, ranging from 0.24 to 0.53 μm. To further elucidate the IPIAMA mechanisms behind these variations, the fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), and the ultraviolet test (UV) testing were conducted. FTIR tests demonstrated that the primary components of mineral aggregates—dolomite, calcite, and quartz—contributed to the physical adsorption increments on asphalt functional groups by 0.0185, 0.0509, and 0.004, respectively. SEM images revealed that dolomite and calcite possessed more surface fissures and pores than quartz. XPS tests showed that calcium carbonate and magnesium carbonate chemically reacted with asphalt, resulting in electron shifts of 0.9 eV and 1.1 eV, respectively, while silicon oxide only exhibited electron shifts when combined with a silane coupling agent-modified asphalt. UV tests demonstrated that lighter asphalt fractions were preferentially absorbed into the pores and micro-cracks of mineral aggregates. Consequently, the complex IPIAMA involved physical adsorption, chemical reactions, and selective absorption, strongly correlating with factors such as mineral composition, surface morphology, and asphalt type.

Insights into the dynamics of supported Au nanoparticles in the wet environments from first-principles and ReaxFF MD simulations

The interactions between metal and oxide supports have been widely studied, where the size effect of metal nanoparticles (NPs) and the gas environment play critical roles in catalytic performance. We employed density functional theory and ReaxFF reactive force field to investigate the size dependent properties of gold NPs supported on cerium dioxide, such as structural dynamics, adsorption, and electronic properties under wet environments. Distinct dynamic behaviors were observed in wet environments compared to vacuum conditions. In the wet environments, the hydroxide (OH) species preferentially adsorbs on the low coordination sites, such as edge sites, of NPs. This selective absorption induces a reconstruction effect on small NPs. Moderate-sized NPs exhibit significant surface reconstruction due to abundant OH adsorption at interface sites. However, this effect is negligible in larger NPs. A high interfacial population of OH significantly contributes the high catalytic performance of moderate-sized NPs. Moreover, OH adsorption modulates the charge distribution within the NPs, leading to their stabilization through OH-induced charge transfer. These findings provide insights into understanding and optimizing reactions in wet environments, offering a foundation for the development of more effective catalyst.

Surface Reconstruction of High-Voltage LiNi0.5Mn1.5O4 Cathode via the Sculpture Method toward Enhanced Stability.

High-voltage LiNi0.5Mn1.5O4 (LNMO) cathodes suffer from severe capacity degradation during long-term cycling due the manganese dissolution and their high operating voltage (∼4.95 V), which pose serious challenges at the surface or interface. Moreover, both traditional ion-doping and passivation layer coating are difficult to apply consistently to LNMO cathode because of their complicated procedures, especially in large-scale production. To address these issues, a strategy employing HNO3/H2O2 leaching in synergy with a sintering process at a mid-temperature of 700 °C was used to achieve selective surface reconstruction. An optimal ratio of reactants was applied to balance the capacity and the cyclic stability of the LNMO cathode. The optimized valence composition of Mn on the material surface mitigates the occurrence of Jahn-Teller distortion, accompanied by a reasonable ratio of ordered and disordered phases and the concentration of oxygen vacancies after sintering, which improves the interface behavior between the electrode and electrolyte. This method delivers a high reversible capacity of 116.5 mAh g-1 after 200 cycles at 0.5 C (1 C = 147 mAh g-1) with a capacity retention of 91.30% and 110 mAh g-1 with a remarkably high capacity retention of 86.85% after 500 cycles at 2 C. This balanced approach, utilizing the protective effects of oxidation (O22-) and the erosive action of acid (H+), is proposed to achieve regional surface reconstruction of advanced LNMO cathode. This opens up a strategy for improving oxide-based cathode materials with low cost and mass production capability, especially favoring high consistency.

Polarization-insensitive compact frequency selective surface with higher angular stability for GSM applications

This article proposes a highly compact, angularly stable, and polarization-insensitive frequency selective surface (FSS) based bandstop filter geometry for shielding electromagnetic (EM) radiations across the GSM band. Each of the unit cells (having dimensions of 10 mm × 10 mm) is made of convoluted meander patterns, which are orthogonally printed on both sides of a dielectric substrate to design this highly compact FSS (the unit cell size is 0.029λ0· 0.029λ0, where λ0 corresponds to the resonance frequency). The metallic pattern on the top layer of the substrate selectively reflects the EM wave for one particular polarization around 890 MHz but transmits the orthogonally polarized wave. In contrast, the pattern printed on the bottom layer behaves oppositely (allowing one polarization and reflecting other polarization), thereby the overall structure exhibiting a bandstop filter response with a 3-dB stop bandwidth ranging from 800 MHz to 960 MHz under dual polarizations. In addition, the geometry exhibits a high angularly stable response till 80° angle of incidence under both transverse electric (TE) mode and transverse magnetic (TM) mode. Good agreement is also observed between the simulated and measured responses for various cases.

Cu2O nanoparticles with morphology-dependent peroxidase mimic activity: a novel colorimetric biosensor for deoxynivalenol detection.

Different morphological Cu2O nanoparticles including cube, truncated cube, and octahedron were successfully prepared by a selective surface stabilization strategy. The prepared cube Cu2O exhibited superior peroxidase-like activity over the other two morphological Cu2O nanoparticles, which can readily oxidize 3,3',5,5'-tetramethylbenzidine (TMB) to form visually recognizable color signals. Consequently, a sensitive and simple colorimetric biosensor was proposed for deoxynivalenol (DON) detection. In this biosensor, the uniform cube Cu2O was employed as the vehicle to label the antibody for the recognition of immunoreaction. The sensing strategy showed a detection limit as low as 0.01ng/mL, and a wide linear range from 2 to 100ng/mL. Concurrently, the approximate DON concentration can be immediately and conveniently observed by the vivid color changes. Benefiting from the high sensitivity and selectivity of the designed biosensor, the detection of DON in wheat, corn, and tap water samples was achieved, suggesting the bright prospect of the biosensor for the convenient and intuitive detection of DON in actual samples.

Ultrahigh Thermal Robustness of High‐Entropy Spectrally Selective Absorbers for Next‐Generation Concentrated Solar Power System

AbstractSpectrally selective absorbers (SSAs) are a critical component in concentrated solar power (CSP) systems, as they maximize sunlight absorption while suppressing heat radiative loss. Despite various SSAs being demonstrated, the challenges remain on the limitations of thermal instability at elevated operating temperatures especially above 650 °C due to component oxidation and diffusion in the absorption layer. To address these challenges, herein a high‐entropy strategy is resorted. By utilizing high‐entropy nitride film as an absorption layer, a double‐layer SSA is prepared by a facile magnetron sputtering method. High‐entropy engineering intensifies and complicates the localized electronic bands, concurrently exhibiting relatively flat bands around the Fermi level, which can significantly enhance 3d interband transition. The resultant SSA delivers the desired spectral selectivity (α/ɛ82 °C = 92.7%/8.4%). Benefitting from the high‐entropy effect, the SSA maintains outstanding optical properties (α/ɛ82 °C = 93.3%/9.4%) even after a 750 °C vacuum thermal treatment for 120 h. Under 1 kW m−2 simulated illumination, the surface temperature of the absorber can easily rise to 95.3 °C, suggesting its remarkable solar‐thermal performance. Furthermore, its effectiveness in parabolic trough collectors (PTCs) is validated. All these competitive performances make the high‐entropy SSA a potentially promising candidate for PTCs.

Oxidized textured stainless steel surface with passivation layer as a high temperature selective solar absorber

A nanocrystalline textured stainless steel (SS) surface passivated with an AlCr oxide layer is proposed for use as a high temperature solar selective absorbers (SSAs). The textured SS surface was prepared by oxidizing in air at 800 °C for 30 min. The heating resulted in outward diffusion of the SS substrate Mn atoms, their oxidation on the surface, and formation of octahedral Mn3O4 nanocrystals, which play a role of textured surface. The passivation AlCr oxide single layer was deposited on the textured surface using reactive RF magnetron sputtering to protect the SS from further oxidation. The solar absorptivity αs and thermal emissivity ε298K of the as-deposited SSAs were 0.84 and 0.165, respectively. In order to study high temperature stability, SSAs were heat treated under air conditions at 600–900 °C for 0.1–300 h. SSAs demonstrated thermal stability at 600 °C for at least 300 h and degradation of optical properties with performance criterion PC < 0.05 at 700, 800, and 900 °C for 300 h, 30 h, and 1 h, respectively. The increase in thickness of the surface Cr2O3 layer on SS substrate was identified as the main degradation mechanism of SSA optical performance. SSAs demonstrated a high activation energy of 330 ± 30 kJ/mol. The obtained data can be used to design high temperature SSAs for concentrating solar energy systems operating under vacuum or air conditions at 500 °C.

Multi-stopband filter based on frequency selective surface

This paper presents the design of a terahertz multi-stopband filter based on a metasurface structure which consisting of multiple metallic strips. By adjusting the dimensions and arrangement of these metallic strips placed on a dielectric substrate, the precise control of the filter performance is achieved. This structure exploits the electromagnetic resonances of metallic strips at terahertz frequencies to generate stopbands, thereby enabling selective filtering. Numerical studies demonstrates that these configurations can produce multiple stopbands within the 4.2 to 15.5 THz frequency range, with tunable center frequencies and bandwidths. Through the research of the transverse and longitudinal filter model structure, the band-stop filter with more stopbands can be realized, and the transmission valley value is kept within 5 %, which is crucial for enhancing filter performance. Moreover, the study reveals that tuning the dimensions of the metallic strips can modulate the resonances, resulting in a redshift of the filter's central frequency and an expansion of the passband width. These findings provide a new method for the performance improvement of terahertz filters, advanced filtering technology and electromagnetic wave control technology.

MXenes: Structure, properties, and photothermal applications

The ever-growing interest in MXenes has been driven by their unique electrical, thermal, mechanical, and optical properties. Due to the presence of diverse surface ligands and defect sites, MXenes exhibit desirable and highly tunable optical response in the solar spectrum. In addition, they have also been found to be effective shields for electromagnetic interference thanks to their selective electromagnetic wave absorption capability. These features collectively provide MXenes with promising potentials for photothermal conversion applications. However, the underlying scientific mechanisms, pathways, and potential impact of photothermal conversion by MXenes remain poorly categorized and understood. In this review, the electronic, optical, and plasmonic properties and potential photothermal mechanism of MXene materials are systematically summarized. Current advances in various photothermal applications as well as challenges and opportunities in relevant fields are also presented. This review provides comprehensive understandings on the fundamental properties as well as a guidance for in-depth investigation of the photothermal conversion mechanism.

A superhydrophilic/air superoleophobic sponge based on layer by layer deposition for high-performance continuous adsorption water in oil

At present, there are few studies on the removal of water from oil, but water in fuel can cause machine malfunctions and even safety accidents, which cannot be ignored. In this study, an oil-resistant superhydrophilic/air superoleophobic sponge (SS-MS) was designed to selectively absorb water from oil. Through layer by layer deposition, polyphenols, particles, and fluorinated surfactants were assembled on the sponge, finally achieving the effect of super hydrophilic and super oil phobic in the air. The contact angle of the modified sponge SS-MS on diesel oil can reach 153°, and the absorption efficiency of water in diesel oil can reach more than 99 %. Moreover, a continuous selective absorption device for water in oil was constructed, the SS-MS sponge can still achieve a water absorption efficiency of 98 % after ten cycles. Importantly, the SS-MS has excellent mechanical and chemical stability under 80 % strain, different pH, UV irradiation times and temperatures. In addition, the materials used in this study are all green and low-pollution substances, and melamine sponge has the advantages of low price, light weight, good elasticity and high porosity. In summary, SS-MS offers a new approach to remove water from fuel and has the potential for large-scale applications.

Fabrication of FeCoNi alloy film via friction-assisted selective area electrodeposition

Nowadays, carbon neutrality target has been receiving a growing attention in academia and industry. In many industry applications, the wear and fatigue damages of bearing components are the frequent failures affecting machine operation. The maintenance and replacement of damaged bearings cause enormous cost in the aspects of consumptions of energy and materials. In this study, a novel technique of friction-assisted electrodeposition (FAED) is firstly demonstrated for surface remanufacturing of worn bearing races. By using the FAED technique, FeCoNi alloys with nanocrystalline were successfully deposited on the selective surface zone. The surface morphology, microstructure feature as well as mechanical properties of the deposited FeCoNi film were quantitatively characterized. The results have indicated that friction load and electrodeposition time have a remarkable effect on the microstructure of the film and its surface finish. The cross-section exhibited a uniform distribution of Fe, Co and Ni. Meanwhile, typical amorphous and polycrystalline features were observed within the deposited film. Additionally, the as-deposited layer shows desired mechanical properties, including hardness, complex modulus and friction coefficient, matching with those of the GCr15 substrate. Scratch test results showed that a good bonding strength between the coating and the bearing steel was achieved. Moreover, the role of friction in the electrodeposition process has been analyzed. This work provides a new route to achieve selective area electrodeposition of alloy films on bearing steel, which can be further developed for metal surface repairing.