Absorption Loss Research Articles

Electrically tunable InAs/GaAs QD in a nanocavity with a transfer-printed ITO electrode

We demonstrate the electrical tuning of InAs/GaAs quantum dots (QDs) embedded in a photonic-crystal (PhC) cavity with transparent indium tin oxide (ITO) electrodes hybrid-integrated by transfer printing. The design includes spacer layers between the cavity and the electrodes to reduce absorption loss while still maintaining a significant bias field. The bottom electrode, PhC cavity, and top electrode were fabricated independently and integrated by transfer printing, and an electrical connection was made by inkjet printing, both implemented locally without affecting the entire chip. We observed the electrical tuning of QD emissions into the cavity mode and Purcell enhancement. This work paves the way for utilizing multiple hybrid-integrated QDs on the same chip.

High-Specific Power Flexible Photovoltaics from Large-Area MoS2 for Space Applications.

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) such as MoS2 and WSe2 are excellent candidates for photovoltaic (PV) applications. Here, we present the modeling, fabrication, and characterization of large-area CVD-grown MoS2-based flexible PV on an off-the-shelf, 3 μm-thick flexible colorless polyimide with polyimide encapsulation designed for space structures. The devices are characterized under 1 sun AM0 illumination and show a V OC of 0.180 V and a specific power of 0.001 kW/kg for a subnanometer-thick, single MoS2 monolayer absorber. Model projections indicate that the polyimide encapsulant introduces negligible absorption loss, and up to 12.97 kW/kg specific power is attainable for a 100 nm-thick MoS2 absorber layer. The devices maintain their performance after repetitive bending down to 5 mm bend radius. An increase in performance is measured after radiation exposure to 1 MeV e- fluence, which is partially attributed to defect healing. Techno-economic analysis shows that even with a lower efficiency, the specific power of a 2D PV array designed for a 6U CubeSat is 2 orders of magnitude higher, and the cost to deploy in space is 2 orders of magnitude less than that of a Si panel used in space. This indicates that the 2D TMDC-based PV has great potential for space applications.

Rheological investigations on frequency selective surface carbon composite microwave absorber.

A high-performance stealth platform is one of the crucial requirements in defence technology that could practically be realized by building effective microwave frequency selective surface (FSS) absorbers. Herein, we report the design and manufacturing of an absorber by tuning the rheology of cell architecture. Initially, a fan-shaped cell (10.4 mm2) was designed for its surface and bulk rheology. The FSS overlayer composition was investigated using SEM, EDX, and XRD and tuned for 0.25% carbon: 1.5% silver to achieve the ink resistivity ∼255 Ω □-1. The bulk rheology was optimized for air (Roha) spacer (thickness ∼2.8 mm), interlayer dielectrics (0.2 mm each), carbon composition (5%), and cell dimension (10.2 mm). Analyses are presented for absorption loss (RC, dB), bandwidth (GHz), resonance dispersion, and constitutive (ε, μ) parameters, compounded with an equivalent circuit model with the settings R = 273.55 Ω, L = 2.25 nH, C = 0.057 pF and the Fabry-Perot reactance mode@10 GHz. The bi-modal response was investigated for induced polarization, electromagnetic fields, volume power distribution, and angular (Θ = 0°-50°) and rotational stability (Φ = 0°-90°) against TE/TM incidences. The FSS pattern was implemented using a screen printing technique to fabricate a prototype absorber and subjected to the free space measurements in an anechoic chamber. The prototype behaviour was found to be commensurate with the simulated performance, thereby achieving a figure of merit of RC ∼-25 dB@10 GHz, accessible bandwidth 4 GHz (in X band) by using the thickness of 0.057 λ0. Details are presented in this study.

Interaction of light with gas-liquid interfaces: influence on photon absorption in continuous-flow photoreactors.

Light interacts with gas bubbles in various ways, potentially leading to photon losses in gas-liquid photochemical applications. Given that light is a valuable 'reagent', understanding these losses is crucial for optimizing reactor efficiency. In this study, we address the challenge of quantifying these interactions by implementing a method that separately determines the photon flux and utilizes actinometric experiments to determine the effective optical path length, a key descriptor of photon absorption. The results reveal the unexpected impact of gas phase introduction in continuous-flow photoreactors. Notably, photon absorption, and consequently the throughput of a photoreactor, can be increased by the introduction of a gas phase. This enhancement arises from the reflection and refraction effects of gas bubbles, which can intensify light intensity in the liquid volume and thereby offset any loss in residence time. The photon absorption losses that were observed were associated with large bubbles and were less significant than anticipated. In contrast, the introduction of small bubbles was found to increase photon absorption, suggesting it is a potential strategy to optimize photoreactor performance.

Electromagnetic shielding enhancement in cement composites: a comparative study of mechanically and thermally recycled carbon fibers

Abstract The recycling of carbon fibers that have reached the end of their service life and their reintegration into new applications hold significant importance from an environmental and sustainable perspective. In this study, the aim is to enhance the electromagnetic wave shielding properties of cement-based composites by incorporating mechanically and thermally recycled and ball-milled carbon fibers at volumetric ratios of 1%, 2%, and 3%. Electromagnetic tests are conducted in the X-band frequency range (8-12.5 GHz), commonly preferred for microwave applications. The obtained results demonstrate an improvement in the SEA (absorption loss )and SET (total power loss) values of the composite with the use of recycled fibers. This improvement is particularly more pronounced in composites containing thermally recycled fibers. The enhanced performance is attributed to the electrical conductivity imparted by carbon fibers. At a frequency of 11.9 GHz, the SET value increased from 8.5 dB for the control sample to 9.2 dB for composites with 3% mechanically recycled fibers and up to 19 dB for composites with 3% thermally recycled fibers. These findings indicate that using recycled carbon fibers enhances the electromagnetic wave shielding properties, with thermal recycling contributing more significantly to this enhancement.

Constructing Grape Bunch Structure Composite Film via Hollow AgNPs Coated Cellulose Nanofibers (CNF@PDA@H-AgNPs)/CNF for Efficient Electromagnetic Shielding, Thermal Conductivity, and Strain Sensing.

Achieving high shielding effectiveness in electromagnetic shielding materials relies heavily on high conductivity, yet simultaneously enhancing the absorption loss remains a persistent challenge. Consequently, the study successfully creates efficient electromagnetic shielding composite films with a unique grape-like bunch structure of hollow nanosilver (HCAF) through layer-by-layer assembly. The utilization of poly(dopamine) (PDA) to anchor nanosilver granules (AgNPs) onto cellulose nanofibers (CNF) results in the formation of CNF@PDA@AgNPs. Subsequently, a surface protection etching method is employed to etch the AgNPs, resulting in hollow nanosilver (H-AgNPs) and the generation of CNF@PDA@H-AgNPs. A composite film featuring a grape bunch structure is fabricated by interweaving high aspect ratio CNF with CNF@PDA@H-AgNPs. A substantial quantity of H-AgNPs creates an abundant interface, while the grape bunch structure establishes an efficient conductive network. That enables the composite film to exhibit excellent impedance matching, excellent conductivity loss, abundant polarization loss, and multiple reflection loss. Therefore, the conductivity of the composite film with a thickness of 148.8 μm reaches 212660 S/m, with SET, SEA, and SER 89.56, 79.03, and 10.53 dB in the X band, significantly better than the 76.9, 55.55, and 21.41 dB of the solid AgNPs composite film. The composite film also exhibits remarkable thermal conductivity (The coefficients of in-plane and out-plane thermal conductivity are 4.61 and 0.17 W/(m·K), respectively), mechanical properties, and strain sensing capabilities, making it significant potential for applications in flexible electronics and other related fields.

Vitamin B12 deficiency in dialysis patients: risk factors, diagnosis, complications, and treatment: A comprehensive review.

Vitamin B12 deficiency is a significant concern among patients with end-stage renal disease undergoing dialysis. However, there hasn't been extensive research conducted on this particular patient group. The reported incidence rates vary widely, ranging from 20% to 90%, reflecting the complexity of its diagnosis. Dialysis patients often face multiple nutritional deficiencies, including a lack of essential vitamins, due to factors such as dietary restrictions, impaired absorption, and nutrient loss during dialysis. Diagnosing vitamin B12 deficiency in these patients is challenging, and addressing it is crucial to prevent complications and improve their overall quality of life. This review paper delves into the available body of evidence on vitamin B12 deficiency in dialysis patients, examining the contributing risk factors, diagnostic challenges, potential complications, and available treatment options. It provides a well-rounded perspective on the topic, making it a valuable resource for researchers, healthcare practitioners, and policymakers interested in addressing the nutritional needs of dialysis patients.

Less, but More: New Insights From Appendicularians on Chordate Fgf Evolution and the Divergence of Tunicate Lifestyles.

The impact of gene loss on the diversification of taxa and the emergence of evolutionary innovations remains poorly understood. Here, our investigation on the evolution of the Fibroblast Growth Factors (FGFs) in appendicularian tunicates as a case study reveals a scenario of "less, but more" characterized by massive losses of all Fgf gene subfamilies, except for the Fgf9/16/20 and Fgf11/12/13/14, which in turn underwent two bursts of duplications. Through phylogenetic analysis, synteny conservation, and gene and protein structure, we reconstruct the history of appendicularian Fgf genes, highlighting their paracrine and intracellular functions. An exhaustive analysis of developmental Fgf expression in Oikopleura dioica allows us to identify four associated evolutionary patterns characterizing the "less, but more" conceptual framework: conservation of ancestral functions; function shuffling between paralogs linked to gene losses; innovation of new functions after the duplication bursts; and function extinctions linked to gene losses. Our findings allow us to formulate novel hypotheses about the impact of Fgf losses and duplications on the transition from an ancestral ascidian-like biphasic lifestyle to the fully free-living appendicularians. These hypotheses include massive co-options of Fgfs for the development of the oikoblast and the tail fin; recruitment of Fgf11/12/13/14s into the evolution of a new mouth, and their role modulating neuronal excitability; the evolutionary innovation of an anterior tail FGF signaling source upon the loss of retinoic acid signaling; and the potential link between the loss of Fgf7/10/22 and Fgf8/17/18 and the loss of drastic metamorphosis and tail absorption in appendicularians, in contrast to ascidians.

Performance Evaluation of Green and Red Lasers in Long-Distance Optical Sensing Using Light Dependent Resistors

This study compares the performance of green (532 nm) and red (650 nm) lasers in optical sensing applications using Light Dependent Resistors (LDRs), focusing on their effectiveness for long-range light intensity detection in environments like bathymetry and surrogate sediment monitoring. The experiment measures resistance changes in LDRs exposed to both wavelengths at incremental distances (1m, 2m, 3m, 4m, and 5m) under controlled laboratory conditions. The key objective is to assess the spectral sensitivity and photoconductivity efficiency of the LDRs with each laser wavelength, providing insights into the optimal laser choice for long-distance sensing systems. The results indicate that green lasers exhibit superior sensitivity compared to red lasers, as evidenced by consistently lower resistance values at all tested distances. This performance advantage is attributed to green light’s higher photon energy and reduced scattering and absorption losses in air and other media, which enhance electron excitation in the semiconductor material of the LDR. These findings align with previous studies suggesting that green light performs better in turbid media, such as sediment-laden water, where precise light transmission and detection are critical for accurate measurements. This comparison is crucial for the design of optical systems used in environmental monitoring and water resource management, where accurate, long-distance light intensity detection is essential. The research highlights the importance of selecting the appropriate laser wavelength to improve the efficiency and reliability of optical sensing technologies, particularly in challenging aquatic environments. The study’s findings provide a foundation for the optimization and calibration of laser-based systems in applications like surrogate sediment monitoring and bathymetric mapping, where maintaining signal strength over long distances is vital. Future work could explore the impact of environmental factors on photodetector efficiency to further advance optical sensing technologies.

Exposing the Role of Silica Nanoparticles and Fiber Stacking in Mechanical, Water Absorption, and Bio-Degradation Behaviors of Banana-Papaya Hybrid Composites

Abstract Natural fiber composites are becoming more valuable in industries due to their eco-friendliness, high strength-to-weight ratio, and cost-effectiveness. This study aimed to develop and evaluate hybrid composites made from banana and papaya fibers, enhanced with silica nanoparticles, bonded with epoxy resin, to assess the effects of fiber layering sequence and silica content on their mechanical, water absorption, and biodegradation properties. Tri-layer composites with configurations such as BPB (Banana-Papaya-Banana) and PBP (Papaya-Banana-Papaya) were fabricated using the hand layup technique. Mechanical testing revealed that PBP composites exhibited superior tensile strength, which further improved when reinforced with silica nanoparticles (SiO2) in various concentrations. The PBP composite with 2 wt% SiO2 displayed optimal performance, showing tensile strength (83 MPa), flexural strength (104 MPa), impact strength (8.4 kJ/m²), and hardness (86 Shore-D) due to effective silica dispersion, enhancing load transfer and interfacial bonding. Thermal stability was also improved by the silica, making this composite suitable for high-temperature applications. Additionally, PBP/3 wt% SiO2 exhibited low water absorption (8% at 15 days) and minimal mass loss (14% at 60 days), highlighting its resistance to environmental degradation, which is essential for humid or marine environments. The PBP/2 wt% SiO2 composite is recommended for use in industries like automotive, manufacturing, and structural engineering, where its high mechanical properties, durability, and eco-friendliness make it a promising alternative to synthetic composites, thus supporting sustainable practices.

Bench to Any Side—The Pharmacology and Applications of Natural and Synthetic Alkylated Hydroxy Cinnamates and Cinnamides

Natural alkylated hydroxy cinnamates (AHCs) isolated from medicinal plants and the thereby designed and synthesized cinnamides are derivatives of hydroxy cinnamic acids such as p-coumaric, sinapic, ferulic, and caffeic acids, which are naturally derived from human dietary sources. The pharmacological properties displayed by AHCs based on their inherent structure range include antioxidant, antimicrobial, antiplasmodial, anti-tyrosinase, Alzheimer’s and Parkinson’s disease therapy, anticancer therapy, metabolic disease therapy, and biopesticides, which have not been reviewed together. Based on their inherent antioxidant, antimicrobial, and UV absorption and their structure–activity relationships, these cinnamyl esters and amides can be used for food preservation in emulsions and oils, as sun-protective components of skin care formulations, and in many other multifunctional applications. In conclusion, the fine-tuning of the structural features such as the type of hydroxy cinnamic acid used, the length of alkyl chains for variable lipophilicity, conversion from cinnamic to propanoic for antioxidants, the increase in methoxy or the change to amino groups to increase the molar absorption coefficient and loss of absorption values, the substitution by halides or amino groups for potent biopesticides, and conversion from esters to amide bonds leads to different AHCs for biomedical, cosmetic, and agriculture applications as an emerging field of investigation that can overall provide natural, safe, biodegradable, and sustainable molecules.

Efficient Quasi-Homogenous Photocatalysis Enabled by Molecular Nanophotocatalysts with Donor-Acceptor Motif.

Polymer semiconductors have attracted much attention for photocatalytic hydrogen evolution, but they typically exhibit micrometer-sized particles in water-suspension, causing severe loss in light absorption and exciton recombination. Here a molecular nanophotocatalyst featuring a donor-acceptor motif is presented that solution is processed via a facile stirring nanoprecipitation method assisted by hydrophilic surfactants, enabling an efficient quasi-homogenous hydrogen evolution. In contrast to the original bulk powder (heterogeneous system), these quasi-homogenous nanophotocatalysts exhibit significantly improved light-harvesting, water-wettability, and exciton dissociation, resulting in distinctly enhanced (by four-order-of-magnitude) photocatalytic hydrogen evolution rate. The optimized nanophotocatalysts (4CzPN/DDBAB/SDBS) generate an outstanding hydrogen evolution rateof 116.42mmolg-1h-1 and apparent quantum yield of 30.2% at 365nm, which are among the highest reported for single-junction organic photocatalysts. The scalability of the quasi-homogenous photocatalysts is further demonstrated using a flow-based flash nanoprecipitation (FNP) processing.

Behavior of TE and TM propagation modes in nanomaterial graphene using asymmetric slab waveguide

Abstract In this article, the conduction of transverse electric/transverse magnetic (TE/TM) propagation modes in nanomaterial graphene utilization of asymmetric dielectric slab waveguide was studied in terms of their applicability in optical fiber communication. Nano-graphene film was deposited on silica substrate and air cladding. Three layers were exposed to electromagnetic waves with a 1.55 µm wavelength and 1 µm thick nanographene film, silica, and air covering to study the performance and optical properties of graphene nanomaterials. The models were influenced by factors such as attenuation wavenumbers, cut-off frequency, mode number, propagation wavenumbers, skin depth, and angles of total internal reflection. The impact of these parameters was assessed through numerical analysis, revealing significant correlations. The modes generated ten numbers of TE and nine numbers of TM mode dependent upon the structure of nanographene, with low loss propagation wavenumber. As the TE/TM modes increase, the decay wavenumbers of the cladding and substrate parameters diminish. This indicates that the magnetic and electric fields undergo extremely rapid decay beyond the film region, which leads to the skin depth for higher TE/TM modes traveling longer distances in the cladding and substrate than do lower-order modes. Therefore, nanographene exhibits good optical properties due to its low absorption loss. The angles of internal reflection are greater in magnitude than the substrate and cladding key angles. Still, in the tenth TE mode, the internal reflection angles are extremely close to the critical angle as a result of the small substrate decay parameter and the near operating frequency. The tenth TE mode is weakly characterized. The characteristics of TE/TM modes in an asymmetric three-layer slab waveguide structure are realized for various mode orders and various parameters of nanographene material. The field profiles of the TE/TM modes are submitted to comprehend these characteristics.

Modeling and optimization of photonic integrated Silicon-LiNbO3 hybrid interferometer for E-S-C-L wavelength band

Abstract The Silicon on Insulator (SOI) is a potential technology for thin-film optical waveguide, enabling the design of optical interconnects, including modulators and interferometers. The manuscript presents the broadband modulator for phase and intensity modulation. The nanoscale optimized interferometric modulator utilizes Silicon (Si) and Electro-optic material Lithium Niobate (LiNbO3) as the guiding material to work in terahertz regime, without any bends in the structure. Optimization of the structure is validated by the evaluation of the confinement factor at the operational wavelength of 1550 nm using Finite Element Method (FEM) based simulation. To excite the SOI interferometric modulator, an external RF signal with a maximum amplitude of 5 V is used. The hybrid structure of Si and LiNbO3-based modulators shows the electro-optic phenomenon caused by nonlinearities, namely the Pockels effect and Kerr effect, which in turn changes the effective mode index, providing π phase shift along with −0.92 dB/cm absorption loss, 117 μm electrode length at V π Volts and 265 nm 3dB optical bandwidth covering the E-S-C-L optical bands. The device footprint calculated is 667 μm2, whereas the active region footprint is ∼46.8 μm2.

Improvement of overall quality of black rice by stabilization combined with solid-state fermentation

The application of black rice in food industry is challenging due to its short shelf life, poor cooking and eating quality. Superheated steam (SS) and far infrared radiation (FIR) are effective ways of stabilization and might be beneficial to solid-state fermentation (SSF). Therefore, stabilization treatments (SS and FIR) combined with SSF by Aspergillus oryzae were applied to furtherly improve the overall quality of black rice in present study. Results indicated that combined treatments were more favorable to shorten cooking time, increase water absorption and solid loss, resulting improvement of cooking quality of black rice. Besides, the significant decrease in hardness and chewiness after combined treatments was also good for the texture improvement. Moreover, black rice after combined treatments showed significantly higher contents of free phenolics, flavonoids, antioxidant activities, and phenolic acids, while their contents in bound form were significantly decreased, leading to significant increase of nutritional properties. Furthermore, black rice after combined treatments had significantly lower acid value and peroxide value during accelerated storage. Particularly, far infrared radiation combined with SSF was the most valued to improve the overall quality of black rice. These improvements were mainly ascribed to the enhancement of hydrolase activities based on the synergistic effect between stabilization treatments and SSF, which led to more significant pasting viscosities decrease, crystal structure destruction, cell wall rupture and starch degradation. The above results will provide a favorable strategy to improve the overall quality of black rice and then promote its consumption and application in food industry. Industrial relevanceThe short shelf life, poor cooking and eating quality severely limit the utilities of black rice in food industry. Heat processing is one of the most efficient strategies used in food industry to improve quality and prolong shelf life. Superheated steam and far infrared radiation are typical innovative heating technologies, and they are more energy efficient and more effective than conventional heating methods. In our previous work, they were effective ways of stabilization to extend the shelf life of black rice, and the starch after above treatments was partially gelatinized, which might be beneficial to the solid-state fermentation and thereby furtherly improve the overall quality of black rice. The present study aims to provide a favorable strategy to improve the overall quality of black rice and then promote its consumption and application in food industry.

Design of a Noise Mitigation System Using Lightweight Graded Micro-Porous Material

Noise is a concern in industries like aviation. Existing acoustic materials have limitations in terms of effective broadband sound attenuation and operating conditions. This work addresses these limitations by designing and developing a noise mitigation system using lightweight graded micro-porous material made from Cenospheres and high-char binder. However, Cenospheres are nearly spherical with rough surfaces, so determining the flow properties of sound propagation is challenging, and direct measurements are expensive. We developed a multivariable-fit inverse method to estimate these properties using an experimental absorption coefficient, validated first with smooth-surface glass beads and then applied to micro-porous material. The determined flow properties were used in a predictive acoustic analysis and validated experimentally. It was demonstrated that a microstructurally graded material is needed to optimize both sound absorption and transmission loss. A graded material system designed for turbofan engine acoustic liners (50 mm thick) met the target broadband sound absorption coefficient of ≥0.50 and transmission loss of ≥20 dB above 500 Hz. The study also highlights that larger particles in thicker layers enhance sound absorption, while a graded micro-structure improves overall acoustic performance. This research offers a novel approach for designing a lightweight acoustic material for aviation, marking a breakthrough in passive noise mitigation technology.

A multifunctional carbon fiber composite film inspired by pumpkin growth toward tunable electromagnetic interference shielding

Carbon fiber composite film is an excellent electromagnetic interference (EMI) shielding material. However, its further application is limited by its single-loss characteristics of electromagnetic waves and unadjustable EMI shielding performance. Inspired by pumpkin growth, a carbon fiber/Co and Ni nanoparticles composite (PCF/CN) with porous, multi-interface, and cross-linked structure was designed through in-situ growth strategy in this work. In this process, Co2+ and Ni2+ were used as ovules while the composite nanofibers were used as the ovaries to provide active sites for seed growth. Polyether (P123) inside the composite nanofibers decompose under a high-temperature treatment and form a porous structure. The polyacrylonitrile (PAN) will form the "peel" during the high-temperature treatment. The PCF/CN provides abundant pores, plentiful non-homogeneous interfaces, and rich conduction paths for the attenuation of electromagnetic waves. After encapsulation with waterborne polyurethane (WPU), the obtained flexible PCF/CN/W composite film displays tunable EMI shielding efficiency using the "Origami" strategy. And the EMI shielding efficiency for PCF/CN-2/W reaches 24.73 dB after two folds due to the absorption loss, reflection loss, conduction loss, and interfacial polarization of the porous multi-interface cross-linked structure. Interestingly, the fabricated composite film also exhibits excellent photothermal conversion performance with fast thermal response time and stability. In addition, the resultant composite film processed sensitive sensing function to detect human joint motion.

Material characterization and thermal performance of polyethylene fiber-reinforced lightweight engineered geopolymer composites subjected to sulfate attacks

The purpose of this research is to use different amounts of fly ash (FA) and ground granulated blast furnace slag (GGBS) to replace ordinary Portland cement (OPC) in polyethylene (PE) fiber-reinforced lightweight engineered geopolymers (LEGP). The mechanical characteristics and durability of these composites are examined, and the results were compared with lightweight engineered cementitious composites (LECC). Expanded glass aggregates were used to produce lightweight LEGP and LECC composites. The composites were exposed to a 5 % Na2SO4 solution for up to 180 days. The performance of LEGP and LECC specimens under normal and sulfate environments was assessed using a variety of tests and analyses, including evaluations of relative slump, density, compressive stress-strain behavior, flexural strength, load-deflection response, split tensile strength, ultrasonic pulse velocity, initial surface absorption, mass change, and mercury intrusion porosimetry (MIP). Microstructural and mineralogical analysis of the composite matrix was conducted using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). Thermogravimetric analysis (TGA) and differential thermogravimetry (DTG) were employed to evaluate the thermal stability of the composites. The results showed that in both normal and sulfate conditions, LEGP specimens with 100 % GGBS showed higher residual compressive, flexural, and split tensile strengths while having minimum initial surface absorption and mass loss as compared with LECC specimens. MIP analysis showed that LEGP mixes with 100 % FA exhibited a more notable increase in pore volume under sulfate exposure leading to reduced performance. LECC specimens subjected to 5 % Na2SO4 solution showed peaks of quartz, mullite, portlandite, and ettringite at higher intensities with calcite and nepheline minerals at lower intensities, while LEGP samples subjected to 5 % Na2SO4 solution were characterized by the formation of quartz, mullite, portlandite, calcite, zeolite, gypsum, and ettringite peaks. FTIR and DTG results showed that C−S−H and Ca(OH)2 were transformed into gypsum and mullite after a sulfate attack for 180 days.

Thermal imaging through hot emissive windows

It is not currently possible for an infrared camera to see through a hot window. The window’s own blinding thermal emission prevents objects on the other side from being imaged. Here, we demonstrate a path to overcoming this challenge by coating a hot window with an asymmetrically emitting infrared metasurface whose specially engineered imaginary index of refraction produces an asymmetric spatial distribution of absorption losses in its constituent nanoscale resonators. Operating at 873 K, this metasurface-coated window suppresses thermal emission towards the camera while being sufficiently transparent for thermal imaging, doubling the thermal imaging contrast when compared to a control window at the same temperature

Comparison between InAs-based and GaSb-based interband cascade lasers with hybrid superlattice plasmon-enhanced claddings

We compare InAs-based and GaSb-based interband cascade lasers (ICLs) with the same 12-stage active region designed to emit at a wavelength of 4.6 µm. They employ a hybrid cladding architecture with the same geometry and inner claddings consisting of InAs/AlSb superlattices but different outer claddings: The InAs-based ICL employs plasmon enhanced n-type doped InAs layers while the GaSb-based ICL employs plasmon-enhanced n-type doped InAs0.915Sb0.085 claddings lattice matched to GaSb. Due to the lower refractive index of n + -InAsSb (n = 2.88) compared to n+ -InAs (n = 3.10) and higher refractive index of separate confinement layers, the GaSb-based ICL shows a 3.8% higher optical mode confinement in the active region compared to the InAs-based ICL. However, the InAs-based ICL has 15.3% lower free carrier absorption losses than the GaSb-based ICL, resulting in approximately equal threshold gains. Experimentally operated in pulsed mode and at room temperature, the GaSb-based ICL shows a 15.3% lower threshold current density, but also 12.8% higher threshold voltage resulting in comparable threshold power densities. Also presented is the influence of geometry and doping variation on confinement factors and calculated free carrier absorption losses in the GaSb-based ICL.