Absorption Properties Research Articles

A novel cellulose-derived graphite carbon/ZnO composite by atomic layer deposition as an over-wideband microwave absorbent.

It is a major challenge to obtain broadband microwave absorption (MA) properties using low dielectric or magnetic nanoparticle-decorated carbon composites due to the limited single conductive loss or polarization loss of the carbon materials used as substrates. Novel pure cellulose-derived graphite carbon (CGC) materials can be used as an exceptional substrate option due to their special defective graphitic carbon structure, which provides both conduction and polarization loss. Herein, CGC@ZnO composites were first synthesized by atomic layer deposition (ALD) for use as microwave absorbents. Thanks to the multiple interfaces composed of graphitic carbon, defective carbon, and polar ZnO molecules, the CGC@ZnO composites exhibited superior MA properties. Specifically, the CZ-3 achieved a minimum reflection loss (RLmin) of -50.5 dB (over 99.999% MA) at 6.16 GHz in 2.98 mm. Amazingly, the maximum effective absorption bandwidth (RL < 10 dB, EABmax) could reach up to 6.48 GHz at only 1.59 mm. The ultra-broadband absorption property is mainly attributed to its strong electromagnetic attenuation capability and excellent impedance matching, making it one of the most promising materials for MA applications.

FRET-based mesoporous organosilica nanoplatforms for in vitro and in vivo anticancer two-photon photodynamic therapy.

We report the synthesis of multifunctional periodic mesoporous organosilica nanoparticles (PMO NPs) with substantial two-photon absorption properties and targeting capability for two-photon excitation fluorescence (TPEF) and photodynamic therapy (TPE-PDT). Prepared using an adapted sol-gel synthesis, the nanoplatforms integrated two silylated chromophores in their three-dimensional matrix to maximize non-radiative Förster resonance energy transfer from a high two-photon absorption fluorophore donor to a porphyrin derivative acceptor, leading to an enhanced generation of reactive oxygen species. Combinations of biodegradable and non-biodegradable bis(triethoxysilyl)alkoxysilanes were employed for the synthesis of the NPs, and the corresponding photophysical studies revealed high efficiency levels of FRET. Next, the cellular uptake and toxicities of pristine and functionalized NPs were evaluated on breast cancer cell lines upon TPEF and TPE-PDT. Notably, the use of TPE-PDT treatment led to high levels of phototoxicity on MCF-7 and MDA-MB-231 cancer cells with substantial effects when compared to one-photon excitation (OPE)-PDT treatment. Preliminary in vivo data on selective and biodegradable NPs showed a significant phototoxicity towards MDA-MB-231 on zebrafish xenograft embryos, making these advanced nanoplatforms promising candidates for future TPE-PDT-based cancer treatments.

First-principles study of the effect of Bi content on the photocatalytic performance of bismuth bromide oxide-based catalysts.

A comprehensive analysis of BixOyBrz has been carried out using first-principles density-functional theory (DFT) to explore the electronic structure, energy band structure, and essential properties related to its photocatalytic performance. DFT calculations reveal that BiOBr, Bi4O5Br2, Bi12O16Br5, Bi24O31Br10, Bi3O4Br, and Bi5O7Br have different indirect bandgap values of 2.46 eV, 2.51 eV, 1.67 eV, 2.21 eV, 2.21 eV, and 2.87 eV, respectively, and these differences reflect the influence of material composition and structure on its electronic structure. When analyzing their optical characteristics, we observe that the dielectric function's real and imaginary components show peaks in the low-energy regime, indicating a material that is more responsive to light in these energy ranges. The absorption spectra show that the BixOyBrz material absorbs the highest amount of UV light absorption, and as the ratio of Bi to Br changes, the absorption spectra exhibit a red shift, which enhances the material's visible light absorption and thus improves the utilization of light. These light absorption properties make BixOyBrz materials potentially advantageous for enhancing photoelectric conversion efficiency, which is particularly important for producing microelectronic and optoelectronic devices.

Transparent broadband metamaterial absorber based on a multilayer ITO structure

In this paper, a multilayer optically transparent metamaterial absorber (OTMA) with microwave broadband absorption properties based on indium tin oxide (ITO) and polydimethylsiloxane (PDMS) is designed. The electrical resonance and magnetic resonance generated by the ITO resonance structure of the upper and middle layers make the absorption rate of OTMA exceed 90% at 6.2 GHz-24.6 GHz. The proposed OTMA has polarization insensitivity and wide-angle absorption properties. The experimental results verified that the OTMA has good absorption properties. The absorber has potential application prospects in stealth device windows and electromagnetic shielding structures.

Suckling Rat Pup Model: Do Caprine Milk Lactoferrin and Immunoglobulins Have Different Digestion and Absorption Properties from That of Human and Bovine Species?

This study aimed to investigate the digestion and absorption properties of caprine milk serum proteins in comparison to human and bovine species by using rat pups to mimic preterm infants. The results indicate that caprine lactoferrin (LTF) had a shorter retention time in the intestine and released a greater number of fragments, resembling human milk LTF more closely. In contrast, caprine immunoglobulins (Igs) were similar to bovine Igs and both exhibited a longer retention time in the intestine. For absorption, caprine Igs could be absorbed intact, which was similar to human and bovine Igs, whereas caprine LTF fragments were found in jejunum but not in plasma of rat pups. This is similar to bovine LTF but differed from human LTF as human LTF could be absorbed intact in plasma of rat pups at 20 min. In addition, the absorption rate of peptides and amino acids from caprine milk serum was similar to that of human milk serum, which was higher than that from bovine milk serum. This study aimed to enhance our understanding of the differences in bioavailability of LTF and Igs derived from caprine, human milk, and bovine milk, thereby offering guidance for selecting protein sources for premature infants.

Near-neutral pH sensing by azoheteroarene dyes.

We serendipitously discovered a novel series of azoheteroarene dyes capable of detecting pH variations in near-neutral solutions. These dyes feature thiazole, thiadiazole, triazole, pyrazole, or benzothiazole heteroaryls linked to hydroxyphenyl azo groups. They exhibit distinctive light absorption properties in aqueous solutions and show notable color changes in a narrow pH range, visible to the naked eye. Both experimental data and quantum calculations suggest a plausible mechanism for their function as pH indicators. Additionally, these azoheteroarene dyes effectively monitor pH in complex environments, and we show their use for detecting the pH change of culture medium containing growing cancer cells.

Advancements in 2D Titanium Carbide (MXene) for Electromagnetic Wave Absorption: Mechanisms, Methods, Enhancements, and Applications.

With the advent of the 5G era, there has been a marked increase in research interest concerning electromagnetic wave-absorbing materials. A critical challenge remains in improving the wave-absorbing properties of these materials while satisfying diverse application demands. MXenes, identified as prominent "emerging" 2D materials for wave absorption, offer unique advantages that are expected to drive advancements and innovations in this field. This review emphasizes the synthesis benefits provided by the unique structural characteristics of MXenes and the performance enhancements achieved through their combination with other absorbing materials. Material requirements, synthesis approaches, and conceptual frameworks are integrated to underscore these advantages. The study provides a thorough analysis of MXene-absorbing composites, going beyond basic classification to address preparation and modification processes affecting the absorption properties of MXenes and their composites. Attention is directed to synthesis techniques, structural design principles, and their influence on composite performance. Additionally, the potential applications of MXenes in electromagnetic wave absorbing devices are summarized. The review concludes by addressing the challenges currently confronting MXene materials and outlining expected developmental trends, aiming to offer guidance for subsequent research in this domain.

Hybrid CIGS-Cobalt Quaterpyridine Photocathode with Backside Illumination: A New Paradigm for Solar Fuel Production.

Chalcogenide-based thin-film solar cell optimized for rear illumination and used for CO2 reduction is presented. Central to this innovation is a thinner, Cu(In,Ga)S2 chalcopyrite absorber coated with a robust metallic top layer, which potentially surpasses the performance of conventional front-illuminated designs. Using cobalt quaterpyridine molecular catalyst, photocurrent densities for CO2 reduction exceeding 10 mA/cm2 at 0.0 V vs. RHE under 1 Sun illumination, and ca. 16 mA/cm2 at -0.25 V vs. RHE were achieved in voltammetry experiments. Controlled potential electrolysis showed catalytic activity over 20 h with selectivity for CO ranging from >92 % (first 4 hours) to 86 % at the end of the experiment. This approach opens limitless possibilities for employing various reduction catalysts, extending far beyond CO2 reduction. It imposes minimal constraints on absorption properties, immobilization methods, and catalyst nature, setting the stage for high-performance, adaptable PEC devices.

DFT Study of Structural, Electronic, and Charge-Transfer Properties of 2-Naphthol Azo Derivatives: Geometric, Positional, and Substituent Effects.

This work represents a systematic computational study of structural and optoelectronic properties of 24 phenylazo-2-naphthol derivatives using the DFT-B3LYP/6-31 + G(d,p) method. The positional isomers of azo compounds have been designed by introducing an azophenyl unit (with and without substituents) at three different (1-, 3-, and 4-) positions of 2-naphthols. This result shows that depending on the linking position of the azophenyl unit and substituents (NO2 and maleimide), the cis-azo, trans-azo, and hydrazo forms of our substituted azo derivatives possess distinguished UV-vis absorption and charge-transfer properties compared to unsubstituted Sudan I derivatives. Our MO calculations show that all Sudan-MI azo derivatives exhibit unique intramolecular charge transfer from the 2-naphthol-azo group as a donor to the maleimide (MI) group as an acceptor. Interestingly, whereas the trans-azo and hydrazo forms of Sudan-MI derivatives show ππ*CT and nπ*CT beside the ππ* and nπ* transitions, the cis-azo Sudan-MI derivatives exhibit mixed (nπ* + ππ*)CT along with ππ*CT, ππ*, and mixed (nπ* + ππ*) transitions. The nature and order of the main azo ππ* (S0 → S2) and nπ* (S0 → S1) transitions alter in Sudan-MI derivatives. The respective substitution of NO2 and MI groups in Para Red and Sudan-MI series leads to the bathochromic shift of λmax (due to π → π* transitions) in comparison to unsubstituted Sudan I derivatives, for example, the 4-positional Para Red trans-azo isomer (λmax 516.9 nm) is 93.8 nm and the 4-positional Sudan-MI trans-azo isomer (λmax 447.3 nm) is 24.2 nm red-shifted compared to the 4-positional Sudan I trans-azo isomer (λmax 423.1 nm). The cis-azo forms of all positional isomers having twisted geometries show different UV-vis spectral behaviors. In general, our studies demonstrate how the variation in the structure of azo compounds impacts their optoelectronic properties, which could be useful in electronic devices.

Identification of Potential Candida albicans Inhibitors Through Pharmacophore Modeling and Virtual Screening Techniques

Fungal infections have increased significantly in recent years and represent a major threat to human health. A large number of these infections are caused by the opportunistic pathogen Candida albicans. Lanosterol 14-alpha demethylase (CYP51), a critical enzyme in the cytochrome P450 family, is a well-established target for antifungal drugs. However, the development of resistance to current antifungal treatments has created an urgent need to develop new inhibitors that are more effective and less likely to promote the emergence of resistance in candida albicans. Azoles are a large and relatively new group of synthetic compounds, of which imidazoles and triazoles are two clinically useful families used in the treatment of systemic fungal infections. In this study, we focused on Candida albicans and used the target protein (PDB code: 1EA1) to perform an In silico analysis of a series of benzimidazole derivatives. The aim was to identify novel chemotherapeutic agents with potential antifungal activity. To discover new Candida albicans inhibitors, pharmacophore models based on the molecular structure of benzimidazole derivatives were generated and validated using various methods. A virtual screening of the Enamine database containing 535,326 molecules was performed based on the combinatorial pharmacophore model. Compounds selected after virtual screening were subjected to molecular docking protocols (HTVS, SP, XP and IFD). 26 new compounds were identified and their absorption, distribution, metabolism and excretion (ADME) properties were calculated. These results suggest that the identified compounds could serve as promising chemical starting points for further structural optimisation in the development of Candida albicans inhibitors.

Investigation of corrosion and water absorption of biomass natural coir fiber/hBN reinforced epoxy hybrid composites using different optimisation approaches

Agricultural waste or agro-waste, including natural fibers and particles from various crop parts, is increasingly recognized as a significant contributor to environmental issues. However, from a circular economy perspective, these materials present an opportunity to be repurposed into new, eco-friendly products. The present study, specifically focuses on understanding the effect of different factors, such as the particulate loading and the size (coir and hBN − 1 to 5 wt%; Coir Powder size (100–200 μm) of the particles on composite’s corrosion rates and water absorption properties. These hybrid particulate composites (HPC) are fabricated using the hand layup process. The study uses a Box-Behnken Design (BBD-L15), a statistical experimental design tool that facilitates the effective investigation of many input parameters and their interactions, to comprehensively investigate these impacts. In addition, the study utilizes four metaheuristic algorithms—the Dragonfly Algorithm (DFO), the Salp Swarm Algorithm (SSA), Teaching Learning Optimization (TLO) and Particle Swarm Optimization (PSO)—alongside regression equations to predict the optimal characteristics of the composite material. To determine the best-performing algorithm, a comparison is made using Deng’s method. The findings indicate that the composite with a higher weight% of hBN particulates exhibits reduced water absorption and corrosion rates. A larger Deng’s Value often indicates better performance. Based on its higher Deng’s Value, the SSO algorithm outperforms other algorithms in minimizing both corrosion resistance (CR) and water absorption (WA). The Deng’s Value for SSO reached a maximum of 0.68, while the other algorithms show comparable but lower performance.

Computational Study of Organotin Oxide Systems for Extreme Ultraviolet Photoresist.

With the advancement of extreme ultraviolet (EUV) lithography technology, the demand for high-performance EUV photoresists has surged. Traditional photoresists struggle to meet the stringent requirements for increasingly smaller feature sizes in semiconductor manufacturing. Among emerging candidates, tin-based materials, particularly Sn12-oxo photoresists, have shown promise due to their superior EUV light absorption properties. Modifying these clusters offers a potential pathway to tailoring their properties for specific lithographic applications. In this study, we investigate the relationship between the photosensitivity of experimentally synthesized Sn12-oxo photoresists and their calculable parameters with quantum chemistry calculations. Key parameters such as bonding energies between metal atoms and organic ligands, molecular ionization potential, electrostatic potential, and HOMO-LUMO gap are identified as critical for predicting photosensitivity. While current research predominantly focuses on replacing counter-anions in Sn12-oxo clusters, there is limited exploration of modifications through the replacement of organic ligands. We examined the effects of electron-withdrawing and electron-donating groups as ligands on the Sn12-oxo cluster's ionization potential and Sn-ligand bonding energy. Our findings suggest a strategy for designing high-performance photoresists, thereby illuminating the path to discovering novel photoresist materials.

Geotechnical characterization of soil-rubber mixtures with well-graded gravel

Shredded rubber from waste tyres has progressively been adopted in civil engineering due to its mechanical properties, transforming it from a troublesome waste into a valuable and low-cost resource within an eco-sustainable and circular economy. Granular soils mixed with shredded rubber can be used for lightweight backfills, liquefaction mitigation, and geotechnical dynamic isolation. Most studies have focused on sand-rubber mixtures. In contrast, few studies have been conducted on gravel-rubber mixtures (GRMs), primarily involving poorly-graded gravel. Poorly-graded gravel necessitates selecting grains of specific sizes; therefore, from a practical standpoint, it is of significant interest to examine the behaviour of well-graded gravel and shredded rubber mixtures (wgGRMs). This paper deals with wgGRMs. The results of drained triaxial compression tests on wgGRMs are analysed and compared with those on GRMs. Stress-strain paths toward the critical state and energy absorption properties are evaluated. The tested wgGRMs exhibit good shear strength and remarkable energy absorption properties; thus, they can be effectively utilised in several geotechnical applications.

Effects of various physical pretreatments and dextranase on the structure and physicochemical properties of porous sweet potato starch: a comparative study

Abstract Porous starch is a type of modified starch that contains a high number of tiny micropores. Due to its natural absorbent properties, porous starch has broad application prospects. Currently, enzymatic hydrolysis is predominantly used for production of porous starch, however, the hydrolysis efficiency is relatively low. In this study, sweet potato porous starch was prepared by combining physical pretreatments with dextranase, and then its adsorption properties were investigated. Ultrasonic, moist heat, and microwave pretreatment methods were used, and the structure, physicochemical properties, and adsorption capacity of resulting porous starches were detected. The microwave-combined enzymatic hydrolysis resulted in a porous starch with more compact pore structure in a shorter time. Additionally, no new chemical groups were observed in the porous starch. The treatment not only increased the solubility of starch to 5.22%, but likewise reduced the swelling power to 6.92%. Furthermore, adsorption capacity of the starch improved remarkably due to increased porosity and specific surface area. Specifically, the oil absorption improved from 51.02 to 102.79%, while the water absorption improved from 58.63 to 120.40%. This study provides an efficient method to produce porous starch from sweet potato with enhanced water and oil absorption capacity, which has promising applications in the food and pharmaceutical industries.

Hybrid CIGS‐Cobalt Quaterpyridine Photocathode with Backside Illumination: A New Paradigm for Solar Fuel Production

AbstractChalcogenide‐based thin‐film solar cell optimized for rear illumination and used for CO2 reduction is presented. Central to this innovation is a thinner, Cu(In,Ga)S2 chalcopyrite absorber coated with a robust metallic top layer, which potentially surpasses the performance of conventional front‐illuminated designs. Using cobalt quaterpyridine molecular catalyst, photocurrent densities for CO2 reduction exceeding 10 mA/cm2 at 0.0 V vs. RHE under 1 Sun illumination, and ca. 16 mA/cm2 at −0.25 V vs. RHE were achieved in voltammetry experiments. Controlled potential electrolysis showed catalytic activity over 20 h with selectivity for CO ranging from &gt;92 % (first 4 hours) to 86 % at the end of the experiment. This approach opens limitless possibilities for employing various reduction catalysts, extending far beyond CO2 reduction. It imposes minimal constraints on absorption properties, immobilization methods, and catalyst nature, setting the stage for high‐performance, adaptable PEC devices.

Investigating the Inhibitory Effects of Paliperidone on RAGEs: Docking, DFT, MD Simulations, MMPBSA, MTT, Apoptosis, and Immunoblotting Studies

Chronic diseases such as diabetes and cancer are the leading causes of mortality worldwide. Receptors for Advanced Glycation End products (RAGEs) are ubiquitous factors that catalyse Advanced Glycation End products (AGEs), proteins, and lipids that become glycated from sugar ingestion. RAGEs are cell surface receptor proteins and play a broad role in mediating the effects of AGEs on cells, contributing to modifying biological macromolecules like proteins and lipids, which can cause Reactive Oxygen Species (ROS) generation, inflammation, and cancer. We targeted RAGE inhibition analysis and screening of United States Food and Drug Administration (FDA) libraries through molecular docking studies that identified the four most suitable FDA compounds: Zytiga, Paliperidone, Targretin, and Irinotecan. We compared them with the control substrate, Carboxymethyllysine, which showed good binding interaction through hydrogen bonding, hydrophobic interactions, and π-stacking at active site residues of the target protein. Following a 100 ns simulation run, the docked complex revealed that the Root Mean Square Deviation (RMSD) values of two drugs, Irinotecan (1.3 ± 0.2 nm) and Paliperidone (1.2 ± 0.3 nm), were relatively stable. Subsequently, the Molecular Mechanics Poisson–Boltzmann Surface Area (MMPBSA) determined that the Paliperidone molecule had a high negative energy of −13.49 kcal/mol, and the Absorption, Distribution, Metabolism, and Excretion (ADME) properties were in control for use in the mentioned cases. We extended this with many in vitro studies, including an immunoblotting assay, which revealed that RAGEs with High Mobility Group Box 1 (HMGB1) showed higher expression, while RAGEs with Paliperidone showed lower expressions. Furthermore, cell proliferation assay and Apoptosis assay (Annexin-V/PI staining) results revealed that Paliperidone was an effective anti-glycation and anti-apoptotic drug—however, more extensive in vivo studies are needed before its use.

Impact of Defect‐Rich Carbon Nanofibers Combined with Magnetic Materials on Broadband Electromagnetic Wave Absorption and Radar Cross‐Section Reduction

Carbon nanofibers (CNFs) exhibit inherent dielectric properties that enhance electromagnetic (EM) wave absorption, yet challenges exist in expanding their effective absorption bandwidth (EAB) and improving flexibility. Many studies fail to adequately consider how structural factors influence performance when combining CNFs with magnetic materials. To address these issues, a 1D carbon nanocomposite is developed by embedding magnetic oxide nanoparticles within CNFs using a simple electrospinning technique. This approach improves membrane flexibility by disrupting rigid alignment and introducing dynamic magnetic interactions, while also creating defect‐rich interfaces that increase the amorphous content (61%) of the CNFsF composite, leading to improved EM wave absorption. The unique macro/mesoporous morphology provides internal interfaces and heterogeneous boundaries that effectively trap and dissipate EM waves. As a result, the flexible CNF composites demonstrate significant EM wave absorption performance, achieving a minimum reflection loss (RLmin) of −39.8 dB at 4.64 GHz and an abroad EAB of up to 7 GHz at only 2.5 mm thickness. Computer simulation technology (CST) simulations indicate a maximum radar cross‐section reduction of 21.1 dB m2, highlighting the material's radar stealth capability. This research advances the development of high‐performance materials and offers new strategies for enhancing absorption properties through composite engineering.

Evaluating the Acoustic Absorption of Modular Vegetation Systems: Laboratory and Field Assessments Using an Impedance Gun

Introducing vegetation is an effective strategy for improving air quality and mitigating the heat island effect. Green modules, which consist of modules that support substrates and various plant species, integrate these elements. This study analyzes the acoustic absorption properties of a specific green wall module using an impedance gun and the Scan and Paint method for laboratory and on-site measurements. The impedance gun method is effective for in situ analysis, offering advantages over standardized techniques for inhomogeneous samples. The sound absorption coefficient of the substrate and the effects of different plant species were measured. Key findings reveal that the substrate primarily influences sound absorption, with its coefficient increasing with frequency, similar to porous materials. Vegetation enhances the acoustic absorption of the substrate, depending on coverage and thickness, with 80–90% of absorption attributed to the substrate and 4–20% to vegetation. However, not all dense plant species improve absorption; some configurations may decrease it. Improvement correlates with substrate coverage and vegetation layer thickness, while the impact of plant morphology remains unclear. These findings confirm vegetation’s potential as an acoustic absorption tool in urban settings. Additionally, green walls can enhance acoustic comfort in indoor environments such as offices and schools by reducing reverberation. They also improve air quality and provide aesthetic appeal, making them a multifunctional solution for modern architecture.

Machine Learning-Aided Examination of Energy Absorption and Mechanical Properties in Steel Lattice Structures

Machine Learning-Aided Examination of Energy Absorption and Mechanical Properties in Steel Lattice Structures

Sustainable sound absorption using shredded plastic particles: Adjusting low-frequency acoustic performance with particle size

This study investigates the sound absorption properties of shredded recycled plastic particles, with a focus on how particle size influences low-frequency acoustic performance. Given the growing environmental challenge posed by plastic waste, this research aims to repurpose such materials into effective, sustainable sound absorbers, contributing to both noise reduction and waste minimization efforts. The sound absorption coefficients and normalized surface impedances of different size fractions, ranging from 45 µm to 3 mm, were measured using the standard two-microphone impedance tube method in accordance with ISO 10534-2. The analysis revealed that smaller particle sizes significantly enhance low-frequency absorption, though at the expense of the maximum absorption coefficient across a broader frequency range. This trade-off underscores the importance of particle size in designing materials tailored to specific acoustic applications. Results indicate that optimal sound absorption shifts towards higher frequencies for larger particle sizes, while finer particles are more effective at lower frequencies. The ability to customize the acoustic properties of shredded plastic particles by selecting appropriate particle sizes is a key outcome of this study. Microscopic examination of the particles revealed a correlation between particle morphology and acoustic performance, with irregular shapes contributing to enhanced sound energy dissipation. The findings suggest that shredded recycled plastic particles are a viable and sustainable option for creating customizable sound-absorbing materials, particularly in applications where low-frequency noise reduction is critical. This research not only advances the understanding of acoustic performance in recycled materials but also supports broader sustainability goals by offering an innovative use for plastic waste in industrial and architectural noise control solutions. In conclusion, this study provides a foundation for the development of eco-friendly, effective sound-absorbing materials from recycled plastics, emphasizing the importance of particle size in achieving desired acoustic properties.