Absorption Properties Research Articles

Investigation of dynamic impact behavior of bighorn sheep horn

The horn of the bighorn sheep is composed of keratin-based biological material that has a tubule-lamella structure, which gives it anisotropic hardening properties under impact loading. This paper aims to investigate the energy dissipation mechanisms inherent in bighorn sheep horns by developing a numerical material model that accounts for the horn’s anisotropic features and strain-rate effects. To this end, a transversely isotropic constitutive model, which includes both anisotropic hardening and strain-rate effects, was formulated to accurately predict the mechanical behavior of bighorn sheep horns. Material characterization was conducted through uniaxial compression tests that were conducted under quasi-static and dynamic conditions. The developed constitutive model was implemented into LS-Dyna via a user-defined material subroutine and was validated against empirical data. The validated numerical model was used to investigate the horn’s mechanical responses under dynamic loading conditions. The paper focused on impact energy dissipation mechanisms, including energy absorption and transition, stress distribution, and displacement wave propagation. The insights gained from this paper are expected to significantly contribute to the development of novel artificial materials with enhanced energy absorption and impact mitigation properties.

Synthesis of Superabsorbent Polymers Based on Sulfated Starch and Study of Their Water Absorption Properties

Synthesis of Superabsorbent Polymers Based on Sulfated Starch and Study of Their Water Absorption Properties

Design and performance study of narrowband polarized colloidal quantum dots photodetector

Abstract Colloidal quantum dot-based (CQD) photodetectors have shown exceptional potential for low-cost, room-temperature broadband imaging. However, the isotropic optical properties of the CQD absorber hinder the capability for multi-dimensional photodetection, such as polarization. Here, we design and theoretically study a CQD photodetector with an encapsulation layer and metal grating layer, which can achieve narrowband polarization sensitivity with a full width at half maximum (FWHM) of 230 nm at a wavelength of 2 μm. We first investigate the effect of the geometric parameters of the architecture. Moreover, we examine the broadband polarized optical properties and analyze the corresponding mechanisms. A large linear polarization ratio of 66 is obtained at an illuminated light wavelength of 2 μm. These results contribute to offering a promising design for constructing narrowband polarized CQD photodetectors, particularly for quantum information processing in the realms of quantum communication and quantum cryptography.

Recent Advances in Additive Manufacturing of Fibre-Reinforced Materials: A Comprehensive Review

Additive manufacturing (AM) plays a significant role in the 4th Industrial Revolution due to its flexibility, allowing AM equipment to be connected, monitored, and controlled in real time. In advance, the minimum waste of material, the agility of manufacturing complex geometries, and the ability to use recycled materials can provide an advantage to this manufacturing method. On the other hand, the poor strength and durability of the thermoplastics used in the manufacturing process are the major drawback that keeps AM behind common production methods such as casting and machining. Fibre-reinforced polymers can enhance mechanical properties, advance AM from the commonly used polymers, and make AM competitive against conventional production methods. The main focus of the current review is to examine the work conducted in the field of reinforced additively manufactured technologies in the literature of recent years. More specifically, this review discusses the conducted research in the composite fibre coextrusion (CFC) additive manufacturing techniques developed over the past years and the materials that can be used. In addition, this study includes an up-to-date comprehensive review of the evaluation of fibre-reinforced 3D printing along with its benefits in terms of mechanical response, namely tensile, flexural, compression and energy absorption, anisotropy, and dynamic properties. Finally, this review highlights possible research gaps regarding fibre-reinforced AM and proposes future directions, such as deeper investigations into energy absorption and anisotropy, to position fibre-reinforced AM as a preferred fabrication method for ready-to-use parts in cutting-edge industries, including automotive, aerospace, and biomedical sectors.

Enhanced Electromagnetic Wave Absorption in Hexaferrite/LSMO Bilayers: Optimization of Structural Design Using a High Frequency Software Simulation

In this study, the electromagnetic (EM) wave absorption properties of a two-layered structure composed of La<sub>0.7</sub>Sr<sub>0.3</sub>MnO<sub>3</sub>-epoxy (10 wt.%) (LSMO) and SrFe<sub>9.5</sub>Co<sub>1.25</sub>Ti<sub>1.25</sub>O<sub>19</sub>-epoxy (10 wt.%) (SFCTO), both exhibiting distinct high-frequency magnetic and dielectric properties, were investigated using a High Frequency Simulation Software (HFSS) simulation tool. LSMO had a high dielectric constant (ε' >30) within the measurement range (0.1-18 GHz), indicating that dielectric loss mechanisms primarily contribute to EM wave absorption. In contrast, SFCTO is a material capable of significantly absorbing EM waves near 10 GHz due to ferromagnetic resonance (FMR). The simulations were validated by comparing the measured and simulated reflection losses (RL) of an unpatterned LSMO/SFCTO bilayer. The RL spectra were examined by varying the layer thickness and pattern size in three configurations: a continuous LSMO/SFCTO structure, a cross-patterned LSMO on SFCTO, and a square-patterned LSMO on SFCTO. In the continuous LSMO/SFCTO structure, tunable absorption frequency bands were achieved by adjusting the layer thickness. However, it was difficult to achieve broadband absorption due to the reflective characteristics of the high dielectric LSMO layer. The cross-patterned LSMO structure on SFCTO demonstrated broader bandwidth absorption, with layer thickness being more influential than pattern width. The square-patterned LSMO on SFCTO exhibited the best broadband EM wave absorption (max Δ<i>f</i> = 7.39 GHz). These results suggest that broader absorption is achievable by partially covering the high-dielectric layer with patterns on a hexaferrite sheet.

Multifunctional composite paper fabricated by graphene oxide/tannin decorated carbon fiber with excellent electromagnetic interference shielding, antibacterial and sound absorption properties

Considering the distinctive oxidative coupling characteristic of tannin acid, it was used as an interfacial interlayer to build a nano-coating structure on the surface of carbon fiber (CF)using amino-modified graphene oxide (GON) via Schiff base reaction. Furthermore, a kind of multifunctional composite paper (PTCF/GON) with excellent electromagnetic interference shielding, antibacterial and sound absorption properties was fabricated using surface modified CF (TCF/GON) and plant fibers. The increased active groups on the surface of TCF/GON improved its hydrophilicity and enhanced its dispersibility in water, which facilitated to form an effective interconnected conductive network of composite paper via traditional wet forming process. Composite paper fabricated by 30 wt% surface decorated CF (PTCF1.5/GON1.2) achieved an electromagnetic interference shielding effectiveness as high as 43.4 dB in X-band, shielding 99.9 % of incident electromagnetic energy. Meanwhile, PTCF1.5/GON1.2 exhibits good sound absorption performance in specific frequency bands, with a sound absorption coefficient of 0.98 around 1180 Hz. Besides, PTCF1.5/GON1.2 also exhibited excellent antibacterial properties. This strategy provides an economical and practical method for manufacturing multifunctional electromagnetic shielding materials with superior performance.

Temperature and Pressure Effects on Phase Transitions and Structural Stability in CsPb2Br5 and CsPb2Br4I Perovskite-Derived Halides.

All-inorganic perovskites exhibit outstanding light absorption properties in the visible range suitable for solar energy applications. We focus on the synthesis of CsPb2(Br,I)5 using mechanochemical procedures. Synchrotron X-ray diffraction (SXRD) data are essential for determining the crystallographic evolution in the 295-753 K temperature range. From room temperature to 573 K, the crystal structure is refined in a two-dimensional (2D) tetragonal framework (space group: I4/mcm) consisting of layers of face sharing [Pb(Br,I)8] polyhedra. Above a transition temperature of Tt = 630 and 621 K, identified from differential scanning calorimetry (DSC) curves for CsPb2Br5 and CsPb2Br4I, respectively, a cubic three-dimensional (3D) corner-sharing perovskite structure is identified, showing substantial Cs and (Br,I) deficiency. A more ionic character for Cs-halide versus Pb-halide is derived from the evolution of the anisotropic atomic displacements. An ultralow thermal conductivity of 0.35-0.18 W m-1 K-1 is related to the low Debye temperatures. From high-pressure SXRD studies, the change in B0 can be attributed to a basic expansion of the unit-cell volume caused by the chemical pressure from iodine within the CsPb2Br5 framework. UV-vis-NIR spectroscopy revealed optical gaps of approximately 2.93 and 2.50 eV, respectively, which agrees with ab initio calculations.

A Developed Approach for Synthesizing Novel Fe3O4/FeO/BaCl2 Composites with Broadband and High-Efficiency Microwave Absorption Performance.

Designing high-performance microwave absorbing materials that are thin and exhibit strong absorption capabilities across a wide frequency range is critical for mitigating electromagnetic pollution through a simple, highly adaptable, and cost-effective approach. However, achieving these three targets remains a significant challenge. In this research a simple approach suitable for large-scale production of microwave absorbing materials, namely, Fe3O4/FeO/BaCl2 composites, is proposed, which includes the processes of chemical coprecipitation and calcination. The above approach can adjust the mass ratio of Fe3O4/FeO while prompt the formation of BaCl2 with mesoporous structure on the surface of Fe3O4/FeO, meeting the need for desirable microwave absorbing performance. Subsequently, the impacts of varying mass ratios of the Fe3O4/FeO/BaCl2 composites on microstructures, magnetic properties, and microwave absorption properties were examined. Based on this investigation, a mass ratio close to 3.5:5.5:1 was determined to be optimal. At this ratio, the Fe3O4/FeO/BaCl2 composites realize an effective absorption bandwidth of 6.70 GHz at only 1.16 mm thickness, covering the whole Ku-band, and the maximum reflection loss can be close to -46.8 dB at 1.4 mm. The robust microwave absorption performance of Fe3O4/FeO/BaCl2 composites can be attributed to heterostructured multi-interface structural design, the comprehensive effects of multiple reflections and dielectric/magnetic losses induced by BaCl2 with mesoporous structure as well as the aggregated Fe3O4/FeO particles. This work may offer insights into designing and preparing effective microwave absorption materials.

Terahertz Wave Absorption of a Rubidium Manganese‐Iron Prussian Blue Phase Transition Material

AbstractRubidium manganese hexacyanidoferrate, Rb0.97Mn[Fe(CN)6]0.99 ⋅ 0.5H2O, which has a three‐dimensional cyanido‐bridged Mn−Fe framework encapsulating Rb+ ions, shows a terahertz (THz) wave absorption property. This compound undergoes a charge‐transfer phase transition between FeIII‐CN‐MnII [high temperature (HT) phase] and FeII‐CN‐MnIII [low temperature (LT) phase] near room temperature. The HT phase exhibits a THz wave absorption at 1.06 THz due to the slow vibration of the heavy Rb+ ions encapsulated in the three‐dimensional framework. By contrast, the LT phase displays a higher resonance frequency at 1.13 THz. This shift to a higher frequency is attributed to the framework shrinkage, which decreases the space available for the trapped Rb+ ion. Indeed, the void volume accompanying the phase transition decreases by 16.4 % from 41.4 Å3 (HT phase) to 34.6 Å3 (LT phase). Tuning the THz wave absorption frequency is necessary for THz devices such as absorbers, switches, filters, and modulators, especially for THz technology with THz waves in the sub‐THz region or near 1 THz.

Optimized design of energy absorption of aluminum foam filled CFRP thin-walled square tube based on agent model

PurposeAluminum foam-filled thin-walled unit structures have received much attention for their excellent energy absorption properties. To improve the energy absorption effect of car energy absorption box under axial compression, this paper optimizes the fiber lay-up sequence, fiber angle and aluminum foam density of aluminum foam filled carbon fiber reinforced plastic (CFRP) thin-walled square tubes.Design/methodology/approachDesign of sample points required to construct the proxy model using design of experiments (DOE) method, and the data sample points of different models are obtained through Abaqus simulation and test. A double high-precision proxy model with the maximum specific energy absorption (SEA) and the minimum initial peak crash force (PCF) as the evaluation index is constructed based on the response surface function method. The NSGA-II multi-objective genetic algorithm was used to optimize the design parameters and obtain the optimal solution for the Pareto front, and the results were verified by using the multi-objective optimization toolbox in design-expert.FindingsThe results show that the optimal solution to the multi-objective optimization problem with the inclusion of the lay-up sequence is ρ = 0.5g/cm3 for a fiber lay-up angle varying in the range ±15–90° and an aluminum foam density varying in the range 0.2g/cm3-0.5g/cm3, with a lay-up method of [±87°/±16°/±15°/±89°]. The two optimization methods correspond to SEA and PCF errors of 2.109% and 4.1828%, respectively. The optimized SEA value is 18.2 J/g and the PCF value is 18,230 N. The optimized design reduces the peak impact force and increases the specific energy absorption, which improves the energy absorption effect of thin-walled energy-absorbing boxes for automobiles.Originality/valueIn this paper, the impact resistance of CFRP thin-walled square tubes filled with aluminum foam is optimized. Based on numerical simulations and experiments to obtain the sample point data for constructing the dual-agent model, we investigate the effect of filling with different densities of aluminum foam under the simultaneous change of fiber lay-up angle and order on its mechanical properties in this process, and carry out the multi-objective optimization design with NSGA-II algorithm.

Effect of Nickel Impurities in Pyrite on Catalytic Degradation of Thiosulfate

The effects of nickel content in nickel-bearing pyrite on photocatalytic properties, light absorption properties, and oxidative decomposition of thiosulfate were studied. The leaching experiments show that the consumption of thiosulfate in the Cu2+-ethylenediamine (en)-S2O32− system increases with an increase in nickel content in nickel-bearing pyrite. The consumption of Cu(en)22+ initially increases and then decreases with an increase in leaching time. There is a clear correlation between the change trend in its consumption and the doping amount of nickel in pyrite. The XPS results show that in the Cu2+-ethylenediamine (en)-S2O32− leaching gold system (temperature 25 °C, time 35 h, solution: 0.1 mol/L S2O32−, 5 mmol/L Cu(en)22+, 200 mL solution), the nickel of pyrite-containing nickel can be transferred to the leaching solution and becomes nickel ion. In this leaching system, Cu(II), which was originally complexed with en, is reduced to Cu(I) in a short time. The consumption of Cu(en)22+ increased rapidly in the 5 h period and then decreased gradually after 5 h. The results showed that the presence of free Ni2+ in the solution facilitated the conversion of bivalent copper ions to monovalent copper ions. Free Ni2+ ions can compete with Cu2+ ions for en ligands. When ethylenediamine complexes with Ni2+, the decomposition of Cu(en)22+ into Cu(en)+ and en occurs more rapidly. And the en, which was originally to be oxidized with Cu(en)+ to form Cu(en)22+, forms Ni(en)22+. As a result, the concentration of Cu(en)22+ continues to decrease in a short period of time.

Exploring the thermal conductivity of green filamentous algae natural fibre: an experimental investigation

Abstract The use of non-renewable resources in thermal insulation has significant environmental impacts. Another major problem faced by the ecosystem is the invasive growth of water weeds. Making sustainable products from waterweeds helps to prevent its overgrowth that disrupts the balance of the ecosystem. This study explores the viability of Green Filamentous Algae (GFA) as an eco-friendly thermal insulation material. GFA was collected from water bodies, cleaned, and processed into two forms: untreated (UTD) and alkali-treated (TD). Experimental investigations were conducted to evaluate the physical properties of GFA, including density, self-ignition temperature, water absorption, moisture absorption, flammability, and thermal conductivity. Results show that the untreated GFA had a density of 402.52 kg/m³, while the treated GFA exhibited a slightly lower density of 392.32 kg/m³. The self-ignition temperature for both untreated and treated GFA was measured between 275°C and 280°C. The water absorption capacity was higher in treated GFA (654.7%) compared to untreated (493.83%). Moisture absorption capacity was 15.14% for untreated GFA and 17.47% for treated GFA. Flammability tests revealed a burning rate of 20.026 mm/min, placing GFA in the combustibility classification 1 (CC1). Thermal conductivity values were found to be 0.308 W/mK (UTD) and 0.273 W/mK (TD), making treated GFA a promising candidate for sustainable insulation applications. This study demonstrates the potential of GFA as a bio-based insulation material and highlights future improvements to enhance its moisture resistance and thermal performance.

Improved Rapid Equilibrium Dialysis-Mass Spectrometry (RED-MS) Method for Measuring Small Molecule-Protein Complex Binding Affinities in Solution.

Rapid equilibrium dialysis (RED) is predominantly used for the characterization of drug absorption, distribution, metabolism, and excretion (ADME) properties in plasma and biological fluids. We describe herein improvements in the use of RED in conjunction with mass spectrometry (RED-MS) to enable robust binding affinity measurements of small molecules for recombinant proteins and complexes from a single dialysis data set. The affinities calculated from RED-MS correlated well with measurements by both surface plasmon resonance (SPR) and affinity selection mass spectrometry (AS-MS). The method was particularly useful for quantifying the binding of small molecules to large protein complexes that were not amendable by common biophysical characterization techniques. Compound pooling and integration with automated liquid handling increased assay throughput and enabled the analysis of hundreds of measurements per week. RED-MS offers a viable option for measuring compound binding in solution and may facilitate small molecule affinity optimization toward difficult-to-drug protein complexes.

Absorption, Fluorescence, and Two-Photon Excitation Ability of 5-o-Tolyl-11 (or 13)-o-tolylisoindolo[2,1-a]quinolines Prepared by Ring-Closing Metathesis and [2+3] Cycloaddition.

We have successfully improved the fluorescence quantum yield of isoindolo[2,1-a]quinoline derivatives by suppressing the rotation of the phenyl groups at positions 5 and 11 (or 13). Additionally, we found that the planarity of these phenyl groups at positions 5 and 13 of isoindolo[2,1-a]quinoline derivatives is crucial for two-photon absorption properties.

Calcium Transport Activity of UV/H2O2-Degraded Fucoidans and Their Structural Characterization

Calcium-chelated polysaccharides have been increasingly considered as promising calcium supplements. In this study, degraded fucoidans (DFs) with different molecular weights (Mws) were prepared after UV/H2O2 treatment; their calcium-chelating capacities and intestinal absorption properties were also investigated. The results showed that the calcium-chelating capacities of DFs were improved with a decrease in Mw. This was mainly ascribed to the increased carboxyl content, which was caused by free-radical-mediated degradation. Meanwhile, the conformation of DF changed from a rod-like chain to a shorter and softer chain. The thermodynamic analysis demonstrated that DF binding to calcium was spontaneously driven by electrostatic interactions. Additionally, DF-Ca chelates with lower Mw showed favorable transport properties across a Caco-2 cell monolayer and could effectively accelerate the calcium influx through intestinal enterocytes. Furthermore, these chelates also exhibited a protective effect on the epithelial barrier by alleviating damage to tight junction proteins. These findings provide an effective free-radical-related approach for the development of polysaccharide-based calcium supplements with improved intestinal calcium transport ability.

Enhancement in Photodetector Sensitivity Using All‐Inorganic Perovskite Absorber RbGeI3 and Copper Bismuth Thiocyanate for Superior Charge Transport

This study investigates a photodetector design using the nontoxic, all‐inorganic perovskite material RbGeI3, which is distinguished by its efficient light absorption and excellent photoelectric conversion properties. Incorporating copper bismuth thiocyanate (CBTS) and indium gallium zinc oxide layers, this design enhances charge transport, leading to a photodetector that exhibits exceptional sensitivity across the visible spectrum, along with a peak responsivity of 0.63 A W−1 and a detectivity of 1.37 × 1013 Jones in the near‐infrared (NIR) at 900 nm. The proposed photodetector exhibits wide‐spectrum detection, encompassing both the visible range and the NIR region. These results position RbGeI3 and CBTS as compelling alternatives to traditional photodetector materials such as Si‐Ge, InGaAs, ZnO, and GaN. Validation is achieved through simulations using the SCAPS‐1D simulator, underscoring the potential of perovskite materials for advanced photodetector applications.

Highly efficient solar steam evaporation via elastic polymer covalent organic frameworks monolith

Three-dimensional solar steam evaporators with efficient water purification performance have received increasing attention recently. Herein, elastic polymer covalent organic frameworks (PP-PEG) containing PEG chains with intriguing adaptability to guests are prepared by forming porphyrin rings. PP-PEG foams demonstrate full spectrum absorbance and excellent photothermal conversion properties. Through well-designed thermal management and optimization of the hydrophilicity and PEG chain length, we obtain a highly efficient solar evaporator with an evaporation rate of 4.89 kg m−2 h−1 under 1 sun in self-contained mode. The optimized solar evaporation rate is increased to 18.88 kg m−2 h−1 under 1 sun with a facile truncated cone reflector, exceeding all known solar steam evaporators. This innovative design holds immense promise for desalination and water purification owing to its simple preparation, high efficiency and durability.

Wave absorption and mechanical properties of SiCf-SiO2f/SiC based on a Jaumann structure

The demand for materials with microwave absorption and mechanical properties in high-temperature harsh environments is increasing in military and civil applications, but their availability is limited. In this study, we present a SiCf-SiO2f/SiC based on a Jaumann structure, where quartz fibers serve as the dielectric layer and SiC fibers act as the lossy layer, with alternating stacking of these two types of fibers. The composite exhibits remarkable characteristics including low density (2.1 g/cm3), high strength (flexural strength of 378 MPa), and temperature insensitivity (reflection coefficient (RC) remains below -7 dB from 25°C to 600°C). Acoustic Emission (AE) monitoring was conducted to evaluate the damage before and after oxidation at 1100°C. Our findings indicate that failure prior to oxidation primarily occurs due to microcracks penetrating into the quartz fibers and crystallization of these fibers, while failure after oxidation mainly arises from BN interface failure. Additionally, both the real and imaginary components of the dielectric constants increase along with reflection coefficients from 25°C to 600°C for SiCf-SiO2f/SiC. The analysis of RC based on different thicknesses demonstrates that the SiCf-SiO2f/SiC can still ensure an RC value below -7dB in X-band. The simulated Radar Cross Section (RCS) values remain unchanged within the temperature range of 25°C-600°C, indicating the temperature insensitivity property possessed by these composites.

Synthesis of a lightweight and dual-band (K and Ka-band) microwave absorber based on cobalt ferrite/mesoporous carbon nanocomposite for stealth technology

Mesoporous carbon has gained significant attention as microwave absorber owing to its lightweight, high surface area and dielectric loss. Herein, for better impedance matching, CoFe2O4/mesoporous-carbon hybrid nanocomposites were synthesized with different content of mesoporous-carbon via a facile hydrothermal method and systematically investigated their K and Ka-band microwave absorption properties. RAMAN analysis establishes the strong interaction amid CoFe2O4 and mesoporous-carbon. Magnetic study confirmed the ferromagnetic nature of the nanocomposite which is helpful for high frequency range absorbers. The CoFe2O4/MC-60 nanocomposite presents a reflection loss of −51 dB at 2.5 mm thickness with an effective absorption bandwidth of 4.2 GHz. The |Zin/Z0| value for this hybrid nanocomposite was closer to 1. The superb absorption properties can be ascribed to best impedance matching and the synergistic effect of the heterogeneous interfaces between CoFe2O4 nanoparticles and carbon. This work can advance the development of magnetic/carbon absorber for high speed communication and military fields.

Seasonal and Spatial Variability of Absorption Properties in Cartagena Bay’s Complex Waters

Characterizing inherent optical properties (IOPs) of water constituents is crucial for remote sensing applications. Remote sensing in Cartagena Bay is particularly challenging due to significant variations in constituent concentrations caused by the seasonal and annual variability of discharges from the Canal del Dique. This article presents the variability in absorption coefficients of phytoplankton, chromophoric dissolved organic matter (aCDOM), and non-algal particles (aNAP) in Cartagena Bay. Absorption coefficients were measured in the laboratory across multiple monitoring campaigns, with seasonal analyses conducted to establish relationships between absorption properties and biogeochemical parameters such as chlorophyll-a, salinity, and turbidity. Results indicate that at 440 nm, aCDOM and aNAP primarily dominate absorption during the rainy season, while aNAP dominates during the dry season. This variation is influenced by inflows from the Canal del Dique. Lower CDOM absorption in 440 nm (aCDOM440), and higher CDOM absorption slope (SCDOM275–295) and higher salinity values were observed during the dry season, which is consistent with the reduced fluvial influx. Spatial variability shows that higher CDOM values prevail in the river plume area during both seasons, with particularly higher values in the rainy season. Median values of aNAP were similar in both seasons, with a strong relationship found between all aNAP data and turbidity (rp = 0.785). Compared to other estuaries, Cartagena Bay exhibits optical characteristics typical of a coastal water body subjected to river discharges, including the elevated turbidity and the high dissolved organic matter influenced by significant inflow from the Canal del Dique. These features highlight the bay’s dynamic interactions with terrestrial inputs. This study provides invaluable information on the optical characteristics of Cartagena Bay, which is crucial for improving the accuracy and effectiveness of remote sensing models for optically active parameters such as turbidity, suspended solids, CDOM, and chlorophyll-a.