Absorption Enhancement Research Articles

Validation of cantilever-enhanced photoacoustic particle-size-resolved light absorption measurement using nigrosin reference particles and Mie modelling

Abstract. Particle light absorption enhancement, also known as the lensing effect, is a complex phenomenon where particles undergo optical transformation as they age. This process is influenced by several factors, including particle size. To investigate the lensing effect, this study introduces and validates a novel method for size-resolved light absorption measurements using nigrosin particles as a model system. The method combines a three-wavelength cantilever-enhanced photoacoustic spectrometer (CEPAS) with a differential mobility analyser (DMA) to achieve particle-size-resolved measurements. Nigrosin, a well-characterised, spherically shaped, and water-soluble material, was selected to demonstrate the feasibility and precision of the approach. The system showed strong agreement (R2>0.94) with Mie-modelled absorption, confirming its reliability. While the broader motivation for this work lies in advancing techniques for studying ageing, coating, and absorption enhancement in black carbon and other atmospheric aerosols, the present study serves as a foundational step by validating the methodology in a controlled and simplified context. Future studies will expand the application of this method to complex systems, including coated and aggregated black carbon particles, to explore phenomena such as absorption enhancement.

Innovative fabrication and absorption enhancement in MgO-stabilized ZrO2/graphene composites

Developing radiative cooling coatings is an efficient and energy-conserving approach for thermal management in electronic devices. Spectral selectivity is crucial to daytime radiative cooling, typically achieved through complex structure or material designs. This work designs a radiative cooling coating with non-selective spectral characteristics for indoor electronic devices. The MgO-stabilized ZrO2/graphene (MSZ/G) powders are prepared in one step through combustion synthesis. Zirconium dioxide powders are utilized as a diluent in the combustion reaction of magnesium powders and carbon dioxide gas. The combustion process can reach a maximum temperature of 1869 °C. This study examines the impact of the diluent content on phase composition, microstructure, and absorptivity. The spectral absorptivity remains nearly constant, reaching up to 0.96, within the spectrum of 2.5–25 μm. The mechanism of absorption enhancement is illustrated in detail. The ZM8A-coated heat sink exhibits a decrease in equilibrium temperature of 9.1 °C when the heat power is 8 W. This outcome validates the effectiveness of non-selective broadband high-emissivity coatings for indoor thermal management. Therefore, this work provides simple and universal guidelines for designing radiative coating of electronic equipment that is not directly irradiated by solar.

An investigative review of the expanded capabilities of thermal/optical techniques for measuring carbonaceous aerosols and beyond.

Carbonaceous aerosols primarily comprise organic carbon (OC) and black carbon (BC). Thermal-optical analysis (TOA) is the most commonly used method for separating carbonaceous aerosols into OC and EC (BC is referred to as elemental carbon EC, in this method). Advances in hardware design and algorithms have expanded the capabilities of TOA beyond just distinguishing OC and EC. However, a comprehensive understanding of the enhanced functionality of TOA is still lacking. This study provides the first comprehensive review of the TOA technique, highlighting expanded capabilities to measure brown carbon (BrC), mass-absorption efficiency, absorption enhancement, source contributions, and refined OC/EC split points. This review discusses the principles, advantages, and limitations of these advancements. Furthermore, the TOA system anticipates further advancements through integration with other instruments, establishing correlations between EC values obtained from different TOA instruments/protocols, correlating between BrC measurements from TOA and non-TOA methods, and developing an algorithm to quantify BrC from progressive absorption Ångström exponent (AAE) values. This review enhances the understanding of the TOA system and its implication for air quality and atmospheric radiation research.

Subcutaneous Injection of Efgartigimod, a New Therapeutic Agent for Generalized Myasthenia Gravis

Patients with generalized myasthenia gravis (gMG) suffer from significant physical and social burdens. Although immunotherapies have been widely used for the treatment of gMG, some patients do not achieve or maintain remission. Recently, several molecular-targeting therapies of gMG, including the intravenous infusion of efgartigimod alfa (efgartigimod IV), a neonatal Fc receptor inhibitor, have been developed and are clinically used in Japan. In 2024, combination subcutaneous injection of efgartigimod alfa and vorhyaluronidase alfa (efgartigimod SC) was approved for the treatment of patients with gMG (only when treatment with steroids or non-steroidal immunotherapies does not lead to sufficient response). Efgartigimod SC contains vorhyaluronidase alfa, which temporarily and locally facilitates diffusion of efgartigimod alfa, resulting in its absorption enhancement. An international phase III, ADAPT-SC study in patients with gMG, including Japanese demonstrates the non-inferiority of efgartigimod SC to efgartigimod IV in reduction of total IgG by 4 weeks treatment. An extension ADAPT-SC+ study demonstrates the long-term safety and tolerability as well as repeatable clinical benefit across multiple efgartigimod SC treatment cycles. As a self-injectable drug, efgartigimod SC may not only contribute to satisfy unmet medical needs in gMG therapy, but also improve convenience for patients and healthcare providers. (Received July 11, 2024; Accepted September 13, 2024; Published January 1, 2025).

Push-pull effect - how to effectively control photoinduced intramolecular charge transfer processes in rhenium(I) chromophores with ligands of D-A or D-π-A structure.

Over the last five decades, diimine rhenium(I) tricarbonyl complexes have been extensively investigated due to their remarkable and widely tuned photophysical properties. These systems are regarded as attractive targets for design functional luminescent materials and performing fundamental studies of photoinduced processes in transition metal complexes. This review summarizes the latest developments concerning Re(I) tricarbonyl complexes bearing donor-acceptor (D-A) and donor-π-acceptor (D-π-A) ligands. Such compounds can be treated as bichromophoric systems with two close-lying excited states, metal-to-ligand charge transfer (MLCT) and intraligand-charge-transfer (ILCT). A role of ILCT transitions in controlling photobehaviour was discussed for Re(I) tricarbonyls with six different diimine cores decorated by various electron-rich amine, sulphur-based and π-conjugated aryl groups. It was evidenced that this approach is an effective tool for enhancement of the visible absorptivity, bathochromic emission shift and significant prolongation of the excited-state, opening up new possibilities in the development of more efficient materials and expand the range of their applications.

Photoelectric characteristic of hybrid thin-film solar cells and metasurface absorbers

Abstract As the demand for high-efficiency, low-cost solar cells continue to increase, existing thin-film solar cells still face many challenges in terms of light absorption efficiency and charge transport performance. To address these issues, we design and study a PEDOT:PSS/CdTe hybrid thin-film solar cell structure combined with a metasurface absorber layer. We use a metasurface structure with a tetragonal embedded ring resonator pattern in the CdTe absorber layer. This structure can produce a strong electric and magnetic field localization effect on the surface of the absorption layer, improving the light absorption rate of the battery. At the same time, the introduction of organic polymer materials (PEDOT: PSS) optimizes the electrode interface quality and reduces the interface defects and composite losses between materials, and further improves the photoelectric conversion efficiency (PCE) of the battery. we introduce traditional absorption enhancement methods (titanium nanoparticle arrays and pyramid TiO2 arrays) to this structure. The solar cell proposed has a spectral response rate of 96.71% and its PCE reaches 35.66%. The research indicates that the new structure holds significant potential for the application of high-efficiency solar cells, offering new ideas for the design and manufacture of solar cells in the future.

Chitosan ‘s role in enhancing nasal drug absorption

The nasal drug delivery system (NDDS) offers a promising route for the administration of therapeutically active compounds, particularly for those requiring rapid onset of action or bypassing the first-pass metabolism. The system provides a direct pathway to the bloodstream, enhancing bioavailability and enabling effective treatment of both local and systemic conditions. Among various enhancement strategies, chitosan, a biopolymer derived from the exoskeletons of crustaceans, has garnered attention as a potent nasal absorption enhancer. Its mucoadhesive properties and ability to temporarily open tight junctions in the nasal epithelium allow for improved drug permeation, particularly for hydrophilic drugs, peptides, and macromolecules. This research focuses on the extraction, characterization, and application of chitosan derived from crab and prawn shells to formulate an effective nasal drug delivery system, particularly for the treatment of migraines. The study aims to develop a nasal spray formulation containing sumatriptan Succinate commonly used migraine medication, to enhance its absorption through the nasal mucosa. The role of chitosan in improving the bioavailability and targeting of drugs to the brain is examined, alongside its biocompatibility and safety profile. Through various in-vitro and ex-vivo studies, the pharmacokinetics, pharmacodynamics, and toxicity of the chitosan-based nasal formulation are evaluated. The findings suggest that chitosan enhances the therapeutic potential of nasal drug delivery systems, providing faster relief with improved drug absorption. This study underscores the potential of natural polysaccharides in revolutionizing drug delivery technologies and improving patient outcomes.

Enhancing Terahertz Absorption Spectrum Based on a Tunable Defect Cavity of One-Dimensional Photonic Crystal in the Combined Coaxial Waveguide

Terahertz (THz) molecular fingerprint spectroscopy provides a powerful label-free tool for detecting trace-amount analytes. Introducing extra microstructures such as metasurfaces to confine the field energy is essential to improve the sensitivity. However, the area of analyte film on conventional enhancing metasurfaces must be larger than the beam spot in a free-space measuring setup. Here, we propose a tunable defect cavity of one-dimensional photonic crystal in the combined coaxial waveguide (CCW) and enhance the broadband THz fingerprint of trace analytes on a much smaller area. The peaks of high Q resonances can form a wide absorption spectrum by changing the length of the rubber part of the coaxial waveguide. For the 0.2 µm α-lactose film sample in the frequency range of 0.48–0.58 THz, the absorption enhancement factor of 89.2 times based on the thickness can be achieved and the sample area is about 1/1700 of that in the free-space measurement with the 5 mm beam waist. We first introduce the coaxial waveguide in the terahertz absorption spectra enhancement. With our proposed structure the analyte volume is effectively reduced which is significant in the real application scenario.

Highly Sensitive InSe Nanosheet Ultraviolet Photodetector Realized Via an Asymmetric Fabry–Pérot Structure

AbstractDue to the wavelength‐dependent absorption, narrow bandgap semiconductors show potential application in ultraviolet (UV) photodetection by thinning. However, the limited absorption in the thinner layer retards their application in high‐performance photodetection. In this paper, the fabrication of an asymmetric Fabry–Pérot (F–P) structure is reported by planar stacking of InSe layer, Al2O3 spacer, and Al back reflector. For the selective absorption enhancement in UV region, the Al2O3 thickness is optimized to be 39 nm by finite element method (FEM). The device presents a peak response at 265 nm illumination, showing the photo‐to‐dark current ratio (Ilight/Idark) of 719. Responsivity (R) and photoconductive gain (G) reach 11.7 A W−1 and 54.7 at the weak light intensity of 0.03 mW cm−2, respectively, which are two orders of magnitude higher than those of the device without the asymmetric F–P structure, revealing the remarkably enhanced absorption. This work shows well compatibility with the manufacturing processes for 2D semiconductor‐based photodetectors and provides a simple and versatile strategy for the application of 2D narrow bandgap semiconductors in high‐performance UV photodetectors.

Simulation of snow albedo and solar irradiance profile with the Two-streAm Radiative TransfEr in Snow (TARTES) v2.0 model

Abstract. The Two-streAm Radiative TransfEr in Snow (TARTES) model computes the spectral albedo and the profiles of spectral absorption, irradiance, and actinic fluxes for a multi-layer plane-parallel snowpack. Each snow layer is characterized by its specific surface area, density, and impurity content, in addition to shape parameters. In the landscape of snow optical numerical models, TARTES distinguishes itself by taking into account different shapes of the particles through two shape parameters, namely the absorption enhancement parameter B and the asymmetry factor g. This is of primary importance as recent studies working at the microstructure level have demonstrated that snow does not behave as a collection of equivalent ice spheres, a representation widely used in other models. Instead, B and g take specific values that do not correspond to any simple geometrical shape, which leads to the concept of the “optical shape of snow”. Apart from this specificity, TARTES combines well-established radiative transfer principles to compute the scattering and absorption coefficients of pure or polluted snow, as well as the δ-Eddington two-stream approximation to solve the multi-layer radiative transfer equation. The model is implemented in Python, but conducting TARTES simulations is also possible without any programming through the SnowTARTES web application, making it very accessible to non-experts and for teaching purposes. Here, after describing the theoretical and technical details of the model, we illustrate its main capabilities and present some comparisons with other common snow radiative transfer models (AART, DISORT-Mie, SNICAR-ADv3) as a validation procedure. Overall the agreement on the spectral albedo, when in compatible conditions (i.e., with spheres), is usually within 0.02 and is better in the visible and near-infrared range compared to longer wavelengths.

Unveiling van Hove Singularity-Boosted Photothermoelectric Response for Wearable Human-Radiation Detection.

Van Hove singularity (vHs), the singularity point of density of states (DOS) in crystalline solids, is a research hotspot in emerging phenomena such as light-matter interaction, superconducting, and quantum anomalous Hall effect. Although the significance of vHs in photothermoelectric (PTE) effect has been recognized, its integral role in electron excitation and thermoelectric effect is still unclear, particularly in the mid-infrared band that suffers from Pauli blockade in semimetals. Here, we unveil the Fermi-level-modulated PTE behavior in the vicinity of vHs in carbon nanotubes, employing ionic-liquid gating. The concurrent enhancement of optical absorption and thermoelectric effect effectively improves the overall photoresponse by tens of folds at the vHs point. Generally applicable to strongly correlated systems such as metallic 1D nanomaterials and 2D Moiré systems, a quantitative correlation between PTE photodetectivity and electronic DOS is derived in the vicinity of the vHs point. Finally, chemically doped PTE mid-infrared detectors with graded doping levels are demonstrated to exhibit human-radiation sensitivity, high flexibility, and high transparency, paving the way for wearable sensor networks in healthcare systems and the Internet of Things.

A-Site Ion Doping in Cs2AgBiBr6 Double Perovskite Films for Improved Optical and Photodetector Performance

Perovskite materials, as emerging semiconductors, have attracted significant attention for their exceptional optoelectronic properties, tunable bandgaps, ease of fabrication, and cost-effectiveness, making them promising candidates for next-generation optoelectronic devices. The all-inorganic perovskite Cs2AgBiBr6 distinguishes itself from other perovskite materials due to its remarkable optical absorption and emission properties, excellent stability, prolonged carrier recombination lifetime, and nontoxic characteristics. However, a deeper understanding of its unique luminescent properties and a further optimization of its structure and performance are still necessary. This study systematically investigates the optimization of Cs2AgBiBr6 double perovskite films through A-site Na+ doping. At an optimal Na+ doping concentration of 3.5% (Na0.07Cs1.93AgBiBr6), the film shows 1.4 times and 2.7 times enhancement in light absorption and photoluminescence intensity, compared to the undoped film. Low-temperature spectroscopy measurements indicate that Na0.07Cs1.93AgBiBr6 exhibits higher exciton binding energy and phonon energy. Based on Na0.07Cs1.93AgBiBr6, the photodetectors demonstrate significant performance improvements, with a high photocurrent response of 10−2 A, a photo-to-dark current ratio (PDCR) of 7.57 × 104, a responsivity (R) of 16.23 A/W, a detectivity (D*) of 2.92 × 1012 Jones, a linear dynamic range (LDR) of 98.75 dB, and a fast response time of 943 ms. This work provides a promising strategy for optimizing all-inorganic perovskite materials through doping and offers guidance for enhancing high-performance photodetectors.

Numerically quantifying the spectral dependence of the absorption enhancement of partially-coated black carbon with complex microphysical properties

The absorption of black carbon (BC) will be enhanced after it is coated with other components, and the research on the enhancement of BC absorption has become a hot topic in climate research in recent years. Some studies have measured the enhancement of BC absorption in certain specific wavelengths, and these measurement results are often used for the analysis of absorption in other wavelengths as well. This work employs numerical methods to quantitatively study the impact of microphysical characteristics of BC with non-absorbing coating on its spectral characteristics of absorption enhancement. This study defines the absorption enhancement Ångström exponent (EABSAE) to quantitatively describe the spectral characteristics of BC absorption enhancement. There are certain differences in the trends of absorption enhancement in different wavelengths with respect to microphysical characteristics, and EABSAE may deviate significantly from 0. The EABSAE of spherical BC usually varies between -2.5 and 2 in the wavelength range of 440–1064 nm. When considering the influence of complex morphology, the statistically average EABSAE of BC assembles with typical particle size distribution is roughly between -2 and 3. In the atmosphere, brown carbon (BrC) can mix with BC, which makes the EABSAE more complex. The EABSAE of BC coated with BrC can have a higher value. Therefore, an EABSAE value of at least 3 is required to prove the existence of BrC. In addition, the uncertainty in the calculation of absorption at other wavelengths was also evaluated in this work based on the absorption enhancement at a given wavelength.

Characterisation of dust aerosols and their absorbing efficiency over South Asia using infrared observations from INSAT-3D Imager

ABSTRACT Radiative impacts of dust aerosols exhibit large regional and temporal heterogeneity, despite the global net cooling effect. Hence, accurate assessment of dust aerosol impacts on weather and climate calls for their regional Characterisation and its proper incorporation in climate models. In this study, dust aerosol distribution and its effects on the absorbing efficiency of aerosol system over South Asia are examined using the Infrared Difference Dust Index (IDDI) derived from the Imager onboard ISRO’s INSAT-3D satellite. IDDI estimated from INSAT-3D agrees well (r ranges from 0.4 to 0.7) with the dust aerosol optical depth (DAOD) from Moderate Resolution Imaging Spectroradiometer (MODIS) and Second Modern-Era Retrospective analysis for Research and Applications (MERRA-2). This shows the potential of this parameter for the Characterisation of dust aerosol and its diurnal and seasonal evolutions. Using IDDI from INSAT-3D, this study further examines the changes in aerosol distribution and characteristics over the Indian landmass and surrounding oceanic regions during severe dust storm episodes. Spatial distribution of dust aerosols and prevailing circulation pattern show long range transport of dust particles from their source regions to faraway locations during the dust events. This is further confirmed by the presence of elevated aerosol layers with high particulate depolarization ratio, observed by Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). An increase in absorbing efficiency of the aerosol system is observed, due to these transported dust particles, over the South Asian region. Dust absorbing efficiency (DAE) is about 20–25K during the dust storm events. This enhancement in radiation absorption due to the wide spread distribution of dust aerosols over a vast domain would significantly alter the circulation dynamics and weather systems over South Asia, especially during pre-monsoon and monsoon seasons.

Bio‐Inspired Graded and Uniform Cylindrical Lattices Fabricated by Material Extrusion 3D Printing: An Experimental and Numerical Investigation

ABSTRACTThe main requirements of the biomedical and aerospace industries are new and innovative lightweight materials. Bio‐inspired structures, which are inspired by various biological designs, have demonstrated notable advancements over traditional lightweight structures. In this study, bioinspired uniform and graded cylindrical triply periodic minimal surface (TPMS) and strut‐based lattice structures were studied for their mechanical qualities and energy absorption capacities fabricated by material extrusion 3D printing using PLA material. It was found that the cylindrical TPMS diamond lattice achieved maximum stress of 78.5 MPa and absorbed 19.14 MJ/m3 of energy, outperforming strut‐based designs with a 48% higher energy absorption than cylindrical BCC lattice structure. Graded designs further improve energy absorption through a better stress distribution. The findings validated the Gibson–Ashby model, highlighting the enhanced load distribution and stress transfer in the strut‐based and TPMS diamond structures. The finite element (FE) model results closely matched the experimental data, confirming its predictive reliability with a maximum error of energy absorption of 7.7%, elastic modulus of 6.9%, and plateau stress of 4.7%. These insights underscore the superior energy absorption and mechanical stability of cylindrical TPMS diamond lattices, indicating their potential for satisfying stringent industrial and technical performance requirements. The novelty of these designs lies in their bioinspired structures and significant enhancements in mechanical performance and energy absorption. Future research should build on these results to design efficient materials tailored to specific needs using FE models to optimize development processes before experimental testing.

Cyclodextrin Inclusion Complexes with Hydrocortisone-Type Corticosteroids.

The hydrocortisone-type corticosteroid (HTC) group includes valuable active pharmaceutical ingredients (APIs) such as hydrocortisone, hydrocortisone acetate, cortisone acetate, tixocortol pivalate, prednisolone, methylprednisolone, and prednisone. Unfortunately, those APIs are characterized by low solubility, which hampers their application and reduces their therapeutic efficacy. The low polarity of HTC molecules allows them to form inclusion complexes with various cyclodextrins (CDs); however, as shown in this review, the type of applied CDs has a major impact on the final properties of the formed complex. HTC-CD complexes have been routinely used for over 40 years to achieve various aims. Most frequently, CDs have been utilized as HTC solubilizers and absorption enhancers in pharmaceutical formulations, as well as for separation and analysis by chromatographic and electrophoretic methods. This article reviews the studies describing the synthesis as well as the biological, physiochemical, and structural properties of the inclusion complexes formed between HTC and various cyclodextrins.

Polymeric nanoparticles for protein and peptide delivery

Protein- and peptide-based medications are recognized for their effectiveness and lower toxicity compared to chemical-based drugs, making them promising therapeutic agents. However, their application has been limited by numerous delivery challenges. Polymeric nanostructures have emerged as effective tools for protein delivery due to their versatility and customizability. Polymers’ inherent adaptability makes them ideal for meeting the specific demands of protein-delivery systems. Various strategies have been employed, such as enzyme inhibitors, absorption enhancers, mucoadhesive polymers, and chemical modifications of proteins or peptides. This study explores the hurdles associated with protein and peptide transport, the use of polymeric nanocarriers (both natural and synthetic) to overcome these challenges, and the techniques for fabricating and characterizing nanoparticles.

Enhancement of the sound absorption of closed-cell mineral foams by perforations: Manufacturing process and model-supported adaptation

Enhancement of the sound absorption of closed-cell mineral foams by perforations: Manufacturing process and model-supported adaptation

Interactions in GO/P3HT thin films: Spectroscopic investigation for organic solar cells

The present study was carried out to investigate the thin film properties of poly (3-hexylthiophene) (P3HT) coupled with graphene oxide (GO) using different spectroscopic techniques. The X-ray diffraction spectrum of GO/P3HT revealed a highly crystalline reflection of GO which is slightly shifted to higher diffraction angles as evidence of interaction with P3HT. Fourier transform infrared confirmed the alteration of P3HT structure upon interaction with GO by the increase in average conjugation length. The reflectance spectrum of GO/P3HT has an observable decrease in percentage reflectance, leading to an enhancement of light absorption. The fluorescent decay curves revealed a decline in exciton lifetime depicting quicker charge transfer, which decreased the exciton diffusion length. Our findings suggest that GO can be the hole transport material in organic solar cells.Graphical abstractSynthesis of GO/P3HT

Current Advancements on Oral Protein and Peptide Drug Delivery Approaches to Bioavailability: Extensive Review on Patents.

Protein and peptide-based drugs have greater therapeutic efficacy and potential application and lower toxicity compared to chemical entities in long-term use within optimum concentration as they are easily biodegradable due to biological origin. While oral administration is preferable, most of these substances are currently administered intravenously or subcutaneously. This is primarily due to the breakdown and poor absorption in the GI tract. Hence, ongoing research is focused on investigating absorption enhancers, enzyme inhibitors, carrier systems, and stability enhancers as potential strategies to facilitate the oral administration of proteins and peptides. Investigations have been directed towards advancing novel technologies to address gastrointestinal (GI) barriers associated with protein and peptide medications. The current review intensifies formulation and stability approaches for oral protein & peptide drug delivery systems with all significant parameters intended for patient safety. Notably, certain innovative technologies have been patented and are currently undergoing clinical trials or have already been introduced into the market. All the approaches stated for the administration of protein and peptide drugs are critically discussed, having their current status, future directions, and recent patents published in the last decades.