Reflective Layer Research Articles

Nurturing a Sense of Belonging in LGBTQIA2S+ Community College Students

Background/context: Challenges faced by community college students have both intensified and transformed since COVID-19 hit in spring 2020. As colleges transitioned operations online and are still gradually returning to in-person teaching and learning, they have had to experiment with how to help students maintain some sense of connection to their peers, their learning, and their schools. This task is complicated in a community college setting because of the size and diversity of student populations; supporting particular populations such LGBTQIA2S+ students calls for additional layers of ongoing reflection. Purpose: Amid increased backlash and a surge in legislation against LGBTQIA2S+ individuals, community colleges face the challenge of helping this marginalized part of our student population feel confident that they belong on campus. In reflecting on efforts by my college to support LGBTQIA2S+students before, during, and after the pandemic, I show how a focus on increasing feelings of belonging are instrumental in retaining LGBTQIA2S+ students.

High-efficiency electromagnetic shielding of three-dimensional laminated Wood/Cu/Ni composites

Construction of ideal dissipation path for layered electromagnetic shielding materials (EMSM) is promising but challenging. Herein, high-efficiency EMSM of three-dimensional hydrophobic wood/Cu/Ni laminated composites have been constructed to achieve laminated composites with high electromagnetic shielding efficiency and low reflection. The electromagnetic gradient structures are obtained via different Cu and Ni deposition times, where the slightly magnetic top Ni coatings serves as electromagnetic (EM) absorption layer and the highly conductive Cu coatings as reflection layer. The hierarchical porous wood structure could extend the EM dissipation path and dissipate EM by multiple reflections. Therefore, the laminated structure exhibits an excellent EM shielding efficiency (average 91.6 dB) at only 0.45 mm thickness between 8.2 GHz and 12.4 GHz in frequency. In addition, the contact angle of laminated composites was 117.8° and the Joule heating was nearly to 0, which broaden their application scenarios in practice. Furthermore, the multilayer Cu/Ni wood-based composites with sandwich-structured can be used as EM shielding gaskets and effectively block wireless power transmission and high frequency EM signal, which shows a prosperous application prospect in defense industry and aerospace.

A mid-infrared ultra-wideband polarization-independent tunable perfect absorber based on Dirac metal materials

A mid-infrared ultra-wideband tunable terahertz absorber based on bulk Dirac semimetal (BDS) is presented. It has a simple three-layer structure: a top BDS metal layer, a middle dielectric layer, and a bottom reflective metal layer. The BDS layer was designed by creating a square cavity and a long rectangular cavity in the center of the BDS rectangle. The long rectangle was then rotated by 90° to form a centrosymmetric cavity. Using CST Studio Suite software, we numerically simulate the absorption characteristics. The simulation results indicate that the absorber achieves a high absorption (>90 %) of about 47.59 THz in the range of 37.5–90 THz when the Fermi energy level is 70 meV. The average absorption exceeds 95 %. In addition, adjusting the Fermi energy level of the BDS alters the absorption bandwidth. The centrosymmetric design of the structure ensures the absorber exhibits insensitivity to different polarization modes and angles of incidence, as well as excellent absorption stability. The designed shock absorber also exhibits excellent tolerance in manufacturing, reducing fabrication challenges and enabling practical applications. In addition, our design possesses the unique ability to modulate light in the mid-infrared band. These remarkable properties position our findings with significant potential in fields such as spectral analysis, optical biosensing technology, infrared sensing, and related applications.

Pharo: A reflective language—Analyzing the reflective API and its internal dependencies

Reflective operations are powerful APIs (Application Programming Interface) that let developers build advanced tools and architectures. Reflective operations are used for implementing tools and development environments (e.g., compilers, debuggers, inspectors) or language features (e.g., distributed systems, exceptions, proxies, aspect-oriented programming). In addition, languages are evolving, introducing better concepts, and revising practices and APIs. Since 2008 Pharo has evolved from Squeak and its reflective API has evolved accordingly, diverging consequently from the original Smalltalk reflective API. With more than 500 reflective methods identified, Pharo has one of the largest reflective feature sets ranging from structural reflection to on-demand stack reification. Those operations are often built on top of the other, creating different layers of reflective operations, from low-level to high-level ones.There is a need to understand the current reflective APIs to understand their underlying use, potential dependencies, and whether some reflective features can be scoped and optional. Such an analysis is challenged by new metaobjects organically introduced in the system, such as first-class instance variables, and their mixture with the base-level API of objects and classes.In this article, we analyze the reflective operations used in Pharo 12 and their interdependencies. We propose a classification based on their semantics and we identify a set of issues of the current implementation. Such an analysis of reflective operations in Pharo is important to support the revision of the reflective layer and its potential redesign.

Multistage microcellular waterborne polyurethane composite with optionally low-reflection behavior for ultra-efficient electromagnetic interference shielding

Electromagnetic interference (EMI) shielding materials with superior shielding efficiency and low-reflection properties hold promising potential for utilization across electronic components, precision instruments, and fifth-generation communication equipment. In this study, multistage microcellular waterborne polyurethane (WPU) composites were constructed via gradient induction, layer-by-layer casting, and supercritical carbon dioxide foaming. The gradient-structured WPU/iron-cobalt loaded reduced graphene oxide (FeCo@rGO) foam serves as an impedance-matched absorption layer, while the highly conductive WPU/silver loaded glass microspheres (Ag@GM) layer is employed as a reflection layer. Thanks to the incorporation of an asymmetric structure, as well as the introduction of gradient and porous configurations, the composite foam demonstrates excellent conductivity, outstanding EMI SE (74.9 dB), and minimal reflection characteristics (35.28 %) in 8.2–12.4 GHz, implying that more than 99.99999 % of electromagnetic (EM) waves were blocked and only 35.28 % were reflected to the external environment. Interestingly, the reflectivity of the composite foam is reduced to 0.41 % at 10.88 GHz due to the resonance for incident and reflected EM waves. Beyond that, the composite foam is characterized by low density (0.47 g/cm3) and great stability of EMI shielding properties. This work offers a viable approach for crafting lightweight, highly shielding, and minimally reflective EMI shielding composites.

Simultaneous measurement of thickness and group refractive index in birefringent crystals

In order to measure the group refractive index and thickness of birefringent crystals simultaneously, a method based on spectral-domain interferometry is proposed. The optical path of each reflection layer of birefringent crystal is converted into spectral interference fringe of corresponding frequency by the principle of spectral-domain interferometry, and the accurate optical path calculation is realized by fast Fourier transform and Hanning-windowed energy centrobaric method. A two-step measurement method was designed to measure the crystal thickness and group refractive index of ordinary ( o ) and extraordinary ( e ) light synchronously by comparing the changes of the optical path before and after the insertion of the sample. The comparison between experimental and theoretical results of LiNbO3 crystals shows that the accuracy of the thickness measured by this system is better than 1 μm and the relative error of the group refractive index is better than 0.15%. The measurement method is simple to implement and has high precision, which is of practical significance for realizing the rapid and high-precision measurement of optical parameters of birefringent crystals.

Electro‐Induced Self‐Reduction TiO2 in Viologen‐Based Ionogels for Multi‐Color Electrochromic Displays

AbstractReflective electrochromic (EC) technology is expected to e‐paper display field, and integrating optical reflective electrolyte as the optical reflective layer is a common strategy for constructing reflective EC devices. Compositing inorganic particles and electrolytes is one of the simplest and most efficient composite methods, but these composite electrolytes usually cannot perform well together in terms of both optical and electrochemical properties. Herein, the TiO2 nanoparticles are added to the ethyl viologen‐based ionogel (T‐EVG, one typical kind of EC/electrolyte) to have the highest visible light reflectivity and the best electrochemical performance compared with SiO2, Al2O3, and ZnO nanoparticles, which is attributed to the electro‐induced self‐reduction TiO2 produced in T‐EVG during EC cycling. Meanwhile, the corresponding EC devices can display red, green, and blue, and have high optical contrast (CIE Lab: ΔE>38), fast switching spend (<4 s, the fastest is 5 Hz), ultra‐low power density (<4.0 mW cm−2), and excellent cycling stability (>85% retained after 10 000 cycles). Finally, a simple 3×3 pixelated EC display array is prepared, and single‐ and multi‐point (including diagonal points) multi‐color display effects are realized through active‐matrix driving and high‐frequency refresh, demonstrating its application value in the high‐performance e‐paper display.

Broadband terahertz absorber based on patterned slotted vanadium dioxide

This study aims to explore broadband terahertz absorbers based on metamaterials by introducing a design featuring patterned slotted vanadium dioxide. This absorber structure includes a vanadium dioxide resonator layer, an intermediate Topas dielectric layer, and an underlying metal reflector layer. To enhance the absorption bandwidth, the vanadium dioxide resonant layer is strategically patterned to optimize impedance matching. Simulation outcomes reveal that, under positive incidence, the absorption rate exceeds 90 % within the frequency range of 1.5–4.2 THz. The absorber demonstrates a substantial absorption bandwidth of 2.7 THz, centered at 2.85 THz, corresponding to a relative bandwidth of 94.7 %. Additionally, through modulation of the conductivity of vanadium dioxide, the absorption peak can be finely tuned, spanning from approximately 2.5 %–99 %. In addition, it's angularly symmetrical and exhibits absorption properties for wide-angle incidence. The tunable terahertz absorber designed in this paper simultaneously achieves high absorption over a wide frequency range, is dynamically tunable, and has a simple structure. From the application point of view, it can provide a way to realize detection, and imaging in the terahertz range.

Impact of the Reflective Layer Thickness on Absorptive Capacity and Emission Coefficient in Thermal Control Coatings

Impact of the Reflective Layer Thickness on Absorptive Capacity and Emission Coefficient in Thermal Control Coatings

Development of Microparticle Implanted PVDF-HF Polymer Coating on Building Material for Daytime Radiative Cooling.

A passive cooling method with great potential to lower space-cooling costs, counteract the urban heat island effect, and slow down worldwide warming is radiant cooling. The solutions available frequently require complex layered structures, costly products, or a reflective layer of metal to accomplish daytime radiative cooling, which restricts their applications in many avenues. Furthermore, single-layer paints have been used in attempts to accomplish passive daytime radiative cooling, but these usually require a compact coating or only exhibit limited cooling in daytime. In our study, we investigated and evaluated in daytime the surrounding cooling outcome with aid of one layer coating composed of BaSO4/TiO2 microparticles in various concentrations implanted in the PVDF-HF polymers on a concrete substrate. The 30% BaSO4/TiO2 microparticle in the PVDF-HF coating shows less solar absorbance and excessive emissivity. The value of solar reflectance is improved by employing micro-pores in the structure of PVDF polymers without noticeable effect on thermal emissivity. The 30% BaSO4/TiO2/PVDF coating is accountable for the hydrophobicity and proportionate solar reflection in the UV band, resulting in efficient solar reflectivity of about 95.0%, with emissivity of 95.1% and hydrophobicity exhibiting a 117.1° water contact angle. Also, the developed coating could cool to about 5.1 °C and 3.9 °C below the surrounding temperature beneath the average solar irradiance of 900 W/m-2. Finally, the results demonstrate that the 30% BaSO4/TiO2/PVDF-HF microparticle coating illustrates a typical figure of merit of 0.60 and is also capable of delivering outstanding dependability and harmony with the manufacturing process.

Achieving high photovoltaic performance in graphene/AlGaAs/GaAs Schottky junction solar cells by incorporating an InAlGaP hole reflector layer

The purpose of this study is to enhance the efficiency of Graphene/AlGaAs/GaAs Schottky junction solar cells by introducing various Ga-based thin-film materials as a hole reflector (HR) layer. These HR layers are designed to minimize the recombination rate at the back contact and increase the photogeneration rate. In order to investigate the effect of various HR layers on the efficiency of GaAs solar cells, a reference cell was simulated with an efficiency of 14%. The simulation was conducted using the Silvaco ATLAS simulator, under AM1.5G light with a power density of 100 mW/cm2. Subsequently, InAlGaP (InAl0.65Ga0.35P), AlGaAs (Al0.2Ga0.8As), and InGaP (In0.5Ga0.5P) thin films were individually introduced as HR layers to the Graphene/AlGaAs/GaAs single junction solar cell (SJSC). The addition of HR layers to the conventional Graphene/AlGaAs/GaAs Schottky junction solar cell was found to improve the short-circuit current density (Jsc) by enhancing carrier collection and reducing back interface recombination. This approach has also led to a significant increase in external quantum efficiency (EQE) at long wavelengths of around 500–900 nm. The results of this study demonstrate that incorporating an InAlGaP HR layer in the proposed structure due to its wide bandgap, higher photogeneration rate, and higher absorption rate significantly improves the EQE by absorbing longer wavelength photons and increases the efficiency of the solar cell by more than 1.6%.

Dual-polarization small-angle strong nonreciprocal thermal radiator with Weyl semimetal

The development of dual-polarization irreversible radiators that can operate without external magnetic field is an arduous task. To avoid the need of strong magnetic field, a dual-polarization nonreciprocal thermal radiator with the introduction of Weyl semimetal is demonstrated. It consists of cross-shaped silicon nanopores, Weyl semimetal, and Ag reflective layer. The simulation results show that the proposed radiator offers both TE- and TM-polarized strong irreversible radiation with an incident angle of 1.6°. The TE-polarized absorptivity and TM-polarized emissivity are 98.8% and 97.6%, respectively. The dual-polarization nonreciprocity exceeds 80%. The physical principle is explained by the electric field energy distribution and impedance matching theory. The demonstrated scheme and radiator have potential application in dual-polarization multi-band irreversible radiation and thermal management.

CoNi/MXene@CoNi/MXene microsphere/silicone rubber multilayered composites for ultra-broadband microwave absorption

2D transition metal carbide/nitride (MXene) nanomaterials have prospective applications in high-performance microwave absorption (MA). However, the excessively high permittivity, absence of magnetic loss, and susceptible oxidizability of MXene severely hinder the enhancement of its MA properties. Here, we used a facile organic solution–phase thermal decomposition method to prepare dielectric–magnetic MXene@CoNi nanocomposites with heterojunctions, which can effectively prevent the oxidation of MXene. Subsequently, the MXene@CoNi nanocomposites were integrated with magnetic CoNi alloys, MXene microspheres (MXene MPs), and a silicon rubber (SR) matrix to construct multilayered CoNi/MXene@CoNi/MXene MPs/SR composites by casting and curing. Benefiting from the multilayered structure and complementary effects of the dielectric and magnetic components, the multilayered CoNi/MXene@CoNi/MXene MPs/SR composites composed of matching, absorbing, and reflective layers showed a remarkable minimum reflection loss of −53.3 dB and an ultra-broad effective absorption bandwidth up to 11.12 GHz at a thickness of 2.96 mm. These results demonstrated the developed multilayered composites are promising candidates for high-performance MA. Our study provides new insights into the development of ultra-broadband MXene-based absorbent materials.

The Morphological and Thermal Characteristics of Hollow-Glass-Microsphere-Coated Phase Change Material–Cow Pie Embedded Recycled Plastic Tiles for Cool Roofs

This study addresses the global plastic waste crisis and the urban heat island effect by developing an innovative solution: recycled plastic roof tiles embedded with phase change material (PCM) and coated with hollow-glass-microsphere-based white paint. The samples were fabricated with cow pie fibers, OM37 and OM42 PCM materials with different wt./vol. values, i.e., 15/50, 20/50, 25/50, 30/50 ratios. The fabricated tiles were coated with hollow glass microspheres to provide a reflective layer. The tiles’ effectiveness was evaluated through morphological examination and thermal analysis. The SEM analysis revealed an excellent bonding ability for the PCM blend, i.e., OM37 and OM42 at a 20/50 ratio (wt./vol.) with cow pie fibers. Adding cow pie fibers to the PCM shifted the melting points of OM37 and OM42, indicating an increased heat storage capacity in both blends. The thermal conductivity results revealed decreased thermal conductivity with an increased cow pie fiber percentage. The recycled plastic roof tile of the PCM composite at a 20/50 (wt./vol.) ratio showed good thermal properties. Upon testing in real-time conditions in a physical setup, the roof tiles showed a temperature reduction of 8 °C from outdoors to indoors during the peak of summer. In winter, cozy temperatures were maintained indoors due to the heat regulation from the roof.

Structural Color Formation of ZnO Nanorods Using Gold as a Seed and Reflective Layer

Structural Color Formation of ZnO Nanorods Using Gold as a Seed and Reflective Layer

Comparison between Two Adaptive Optics Methods for Imaging of Individual Retinal Pigmented Epithelial Cells.

The Retinal Pigment Epithelium (RPE) plays a prominent role in diseases such as age-related macular degeneration, but imaging individual RPE cells is challenging due to their high absorption and low autofluorescence emission. The RPE lies beneath the highly reflective photoreceptor layer (PR) and contains absorptive pigments, preventing direct backscattered light detection when the PR layer is intact. Here, we used near-infrared autofluorescence adaptive optics scanning laser ophthalmoscopy (NIRAF AOSLO) and transscleral flood imaging (TFI) in the same healthy eyes to cross-validate these approaches. Both methods revealed a consistent RPE mosaic pattern and appeared to reflect a distribution of fluorophores consistent with findings from histological studies. Interestingly, even in apparently healthy RPE, we observed dynamic changes over months, suggesting ongoing cellular activity or alterations in fluorophore distribution. These findings emphasize the value of NIRAF AOSLO and TFI in understanding RPE morphology and dynamics.

A theoretical study on optical field distribution and absorption of stacked thin films supported by a reflective back layer

The stacked thin films have recently been of great interest for enhancing the optical and thermal absorption of the system via their specific optical properties depending on the optical wavelength and layer thickness. Here, by using Maxwell’s equation for the electromagnetic fields penetrating thin films, we simulated in detail the absorption of the nanometer-thick thin film of several materials, such as Au, Ag, Cu, and Al, and figured out the optimal thickness range for the outer layers exposed to incoming field to optimize the energy harvesting. In particular, the absorption of the film supported by a totally reflective layer at the back of the structure could be significantly enhanced, and the maximal absorption happens at a layer much thinner than that in the case of the film solely irradiated by the field. These results could help suitably choosing of detailed thickness for the structure to optimize the field effect on a specific layer.

Enhancing Photoconversion Efficiency by Optimization of Electron/Hole Transport Interlayers in Antimony Sulfide Solar Cell using SCAPS-1D Simulation.

Enhancing photoconversion efficiency in a solar cell with the composition "glass/Mo/CUSbS3/ Sb2S3/CdS/i:ZnO/AL:ZnO" by varying the thickness of the absorption layer (Sb2S3) and adding a secondary absorption layer was performed. The thickness of the original absorption layer (Sb2S3) was gradually increased from (1 µm) to (3.5 µm). The best efficiency (23.14%) and filling factor (87.52%) were achieved with an absorption layer thickness of 3.5 µm. This indicates that a thicker absorption layer can enhance efficiency.
 A secondary absorption layer was introduced between the original absorption layer and the reflection layer. Several materials were considered for this secondary absorption layer, including MAPbI3, Sb2Se3, CZTS, and CZTSe. The best-performing secondary absorption layer was found to be Sb2Se3. The solar cell structure, after combining it with the best reflection layer (CUSbS3) and the optimized thickness for the original absorption layer (3.5 µm), was established as "glass/Mo/CUSbS3/Sb2Se3/Sb2S3/CdS/i:ZnO/Al:ZnO".
 The optimized solar cell configuration yielded the best conversion efficiency (27.01%) and a high filling factor (85.12%).
 These results highlight the significance of layer thickness and the addition of secondary absorption layers in enhancing the solar cell efficiency. The final configuration demonstrates substantial improvements in efficiency and suggests that thoughtful design and material choices can lead to more efficient photovoltaic devices.

Highly reflective TiO2 layer on AlN substrate: Enabling high quality laser lighting

Phosphors in glass films (PiFs) is considered ideal conversion materials for laser lighting, but heat dissipation issue is the main challenge limiting its development. Therefore, it is urgent to find more excellent heat dissipation materials. Herein, we proposed to use AlN with high thermal conductivity as the substrate, and innovatively introduced TiO2 coating to improve the interface reflection ability and solve the possible problems of shedding and cracking. After a series of optimizations, the LSN PiG-TiO2-AlN (PTA) color converter obtained a high thermal conductivity of 29W m−1k−1 and a low surface temperature. At an input power of 5.2W, the luminous efficiency can reach 175 lm/W and the relative initial intensity can still be maintained by 95.3% at 200 °C. Benefiting from the extremely strong heat dissipation capacity of the AlN substrate, the LSN PTA color converter maintains its relative luminous intensity at 95 % of the initial intensity after 24 h of continuous illumination, which is the best value recorded so far. In addition, LSN PTA is combined with CaAlSiN3:Eu2+ phosphor to achieve high-quality white light with a CRI of 82.5. The above results indicate that LSN PiG-TiO2-AlN color converters have a promising research prospect in the field of laser lighting.

Recasting Regional Lighting for Shadow Removal

Removing shadows requires an understanding of both lighting conditions and object textures in a scene. Existing methods typically learn pixel-level color mappings between shadow and non-shadow images, in which the joint modeling of lighting and object textures is implicit and inadequate. We observe that in a shadow region, the degradation degree of object textures depends on the local illumination, while simply enhancing the local illumination cannot fully recover the attenuated textures. Based on this observation, we propose to condition the restoration of attenuated textures on the corrected local lighting in the shadow region. Specifically, We first design a shadow-aware decomposition network to estimate the illumination and reflectance layers of shadow regions explicitly. We then propose a novel bilateral correction network to recast the lighting of shadow regions in the illumination layer via a novel local lighting correction module, and to restore the textures conditioned on the corrected illumination layer via a novel illumination-guided texture restoration module. We further annotate pixel-wise shadow masks for the public SRD dataset, which originally contains only image pairs. Experiments on three benchmarks show that our method outperforms existing state-of-the-art shadow removal methods. Project page in: yuhaoliu7456.github.io/RRL-Net.