Attenuation Ability Research Articles

Enhanced electromagnetic wave absorption of La0.8Ca0.2Fe1-xMnxO3 boosted by lattice distortion and double-exchange

Perovskite LaFeO3 with ABO3 structure is regarded as a potential candidate in electromagnetic wave absorption, considering its unique dielectric-magnetic coupling loss mechanism. However, the limited attenuation ability of pristine LaFeO3 restricts its further application. In this work, the dual doping strategy is carried out to improve the dielectric and magnetic loss capacity. Ca and Mn dual doped La0.8Ca0.2Fe1-xMnxO3 are prepared by spray pyrolysis method. The minimum reflection loss (RLmin) of La0.8Ca0.2Fe0.2Mn0.8O3 reaches −52.3 dB with an effective absorption bandwidth (EAB) of 3.92 GHz at the fitting thickness of 2.08 mm. The enhancement of the dielectric loss mainly originates from strengthened dipole polarization induced by the Jahn-Teller distortion which is caused by Ca and Mn double doping. The magnetic loss can be attributed to the improvement of double-exchange between Fe3+ –O2- -Mn3+ and Mn3+ –O2- -Mn4+ owing to the introduction of Mn. This work provides new insights into regulating the electromagnetic wave absorption performance of perovskite.

ZIF‐67‐Derived Co@Carbon Polyhedra Anchored on Reduced Graphene Oxide with Multiple Attenuation Abilities for Full X‐ and Ku‐Band Microwave Absorption

High‐performance microwave absorption (MA) materials are attracting growing attention to solve the expanded electromagnetic interference problems. Herein, zeolitic imidazolate organic frameworks (MOF)‐67 (ZIF‐67) are grown in situ on the sheet of graphene oxide (GO) through the coordination of Co2+ with oxygen functional groups. Through carbonization in an inert atmosphere, Co@carbon polyhedra (Co@CP)‐decorated reduced GO composites (Co@CP‐rGO) with a large number of heterogeneous interfaces are successfully obtained. The composites demonstrate excellent MA performance. With a filler loading of 10 wt%, the optimal minimum reflection loss (RL) of the composite can reach −54.6 dB. More importantly, the composites with thickness of 3.5 and 2.5 mm show the effective absorption bandwidth (RL < −10 dB) of 4.75 GHz (8.18–12.93 GHz) and 6.56 GHz (11.44–18 GHz), fully covering the X‐ and Ku‐band. It is proposed that the synergistic effect of multiple dielectric loss, magnetic loss, reflections and scattering contributes to the high MA performance.

Analytical Modeling of Wave Absorption Performance in Gradient Graphene/Polymer Nanocomposites.

Due to the low impedance matching caused by the high dielectric permittivity of graphene, the strong absorption of electromagnetic waves by graphene/polymer nanocomposites is challenging. In this paper, an analytical model for microwave absorption based on Maxwell's equation and the effective medium theory, considering the interface effect, was constructed to explore the effect of the gradient distribution of graphene in the polymer matrix on its microwave absorption performance. The outcome indicated that the impedance of the composites matched well with the air, and its attenuation ability for electromagnetic waves was obviously improved as the graphene concentration was distributed in a gradient form. For instance, when the thickness of the material is 10 mm, based on the optimal concentration of the homogeneous composites being 0.7 wt%, the graphene concentration range of the gradient composites is set to 0.7-0.9 wt% and distributed in three gradient forms of linear, parabolic, and 0.5 power. The results show that the microwave absorption performance is significantly improved compared with the homogeneous composites. Among them, the effective bandwidth on the 0.5 power distribution is 5.2 GHz, 0.5 GHz higher than that of the homogeneous composites. The minimum reflection loss (RL) is as low as -54.7 dB, which is 26.26 dB lower than that of the homogeneous composites. This paper contributes to the design and application of gradient absorbing structures.

Bandgap tunability and impact mitigation enhancement of hybrid graded origami-inspired metamaterials with multiple resonators

Origami structure has become an important design source of metamaterials because of its extremely rich form and infinite design space. In order to improve the wave attenuation and impact mitigation ability of origami structure, a hybrid graded origami-inspired metamaterials with multiple resonators is proposed. The bandgap characteristics, transmission spectrum and impact resistance of the proposed metamaterials are analyzed in detail by numerical simulation. The results show that multiple local resonance mechanisms can open two new bandgaps compared to the single local resonance case, and the bandgap boundary is very sensitive to the dimension of resonance units. In particular, the resonance peaks of the origami metamaterials are substantially weakened due to the presence of dimensional gradients, which allows multiple bandgaps to merge into an ultra-wide bandgap (bandwidth up to 8.9 kHz), about five times than the original bandwidth. According to the time domain and frequency domain analysis results, it can be found that the amplitude of reaction force is significantly reduced in the bandgap range, and the ultra-wide frequency domain (2.9–10 kHz) with sustainable-low peak appears. Moreover, the asymmetry and graded design of unit-cell also affects the ability of dissipate and attenuate wave energy and delay the wave transmission time. In addition, the local-resonant origami metamaterials are fabricated by 3D printing technology, and the experimental results are in good agreement with the numerical simulation results. This study is expected to provide valuable ideas in crashworthiness design and impact wave protection of important equipments.

Vibration attenuation and wave propagation analysis of 3D star-shaped resonant plate structures and their derivatives with ultra-wide band gap

Based on the local resonance effect of elastic waves, three single-phase acoustic metamaterials are proposed in this paper. Based on the finite element method and Bloch's theorem, the energy band structure diagrams and vibration modes are plotted, and the band gap properties and band gap opening mechanism of these structures are explored. New structures possessing lower frequency band gaps are obtained by topological optimization. The transmission curves verify the accuracy of the band gap and the vibration attenuation ability of the structure. Finally, the structural parameters were adjusted and the effect of each parameter change on the band gap characteristics was analyzed. The results show that the proposed structure has a maximum band gap coverage of 72.4 % and a strongest attenuation peak of less than −400 (dB) due to the occurrence of a local resonance. This paper provides a methodology for analyzing the vibration and noise reduction performance of single-phase material phononic crystals, as well as a three-dimensional phononic crystal with potential for practical applications.

Carbon nanotubes-encapsulated Co/Co7Fe3 nanocomposites: Achieving wideband electromagnetic wave absorption at ultrathin-thickness by regulating magnetic phase ratio

Nowadays, through various strategies such as composition regulation and structural design, the electromagnetic wave (EMW) attenuation ability of composites has been significantly improved. Nevertheless, at ultra-thin sample matching thicknesses, it is still a challenge for absorbing materials to possess high-intensity and wide bandwidth simultaneously. In this work, the cobalt/iron nitrilotriacetic acid chelates (Co/Fe-NAC) were fabricated by a one-step hydrothermal self-assembly strategy. Then, a series of carbon nanotubes-encapsulated Co/Co7Fe3 (Co/Co7Fe3@CNTs) nanocomposites were constructed by coating glucose hydrothermal carbon on Co/Fe-NAC precursors and subsequent calcination process. By controlling the Co/Fe ion content, the magnetic phase ratio in the product can be efficiently regulated to comprehensively optimize microwave absorption (MA) performance. The minimum reflection loss (RL) of the optimized sample is −42.6 dB at only 1.1 mm thickness, and the effective absorption bandwidth (EAB) reaches up to 10.1 GHz (7.9–18 GHz). Surprisingly, for all samples, the widest EAB can exceed 8.2 GHz at the ultra-thin thickness (thinner than 1.3 mm) and the strongest RL values are all below −30 dB (99.9 % EMW can be absorbed). Such excellent MA performance is attributed to the strong magnetic loss of highly dispersed magnetic nanoparticles, the strong dielectric properties of carbon nanotubes and shells, optimized impedance matching, as well as the synergistic effect of multi-dimensional heterogeneous components and structures. Moreover, the high-frequency structure simulator (HFSS) was used to further analyze the multi-polarization behaviors and heterogeneous magnetic coupling effect. This work may provide a new direction to the fabrication of efficient and ultra-thin absorbers, and Co/Co7Fe3@CNTs nanocomposites may become a promising candidate for practical application in the MA field.

Dion‐Jacobson 2D Perovskite 2AMPPbBr4 with Type II Band Alignment for Highly Sensitive X‐Ray Detection

Abstract2D hybrid perovskites have emerged as a promising alternative material to address the environmental stability and the ion‐migration of the 3D perovskites for direct X‐ray detector applications. Nevertheless, the X‐ray detection performance of the 2D hybrid perovskites still lags because of its low X‐ray attenuation ability and limited solubility for thick film deposition. Here, a high‐performance X‐ray detector in Dion‐Jacobson 2D hybrid perovskite, 2(aminomethyl) pyridinium lead bromide (2AMPPbBr4), is studied. 2AMPPbBr4 exhibits an ultra‐short interlayer distance of 3.43 Å, leading to high X‐ray attenuation ability. Furthermore, DFT results indicate that 2AMPPbBr4 exhibits type II band alignment between 2AMP2+ ligand and the [PbI6]4− layers, facilitating effective spatial separation of photo‐generated carriers. The X‐ray detector made of 2AMPPbBr4 with an average thickness of 200 µm is realized via an improved drop‐casting method. An improved X‐ray sensitivity of 3933.88 µC Gy−1 cm−2 and a low detection limit of 4.17 nGy s−1 is achieved. This work paves the way for high‐performance X‐ray detectors based on the emerging 2D perovskite materials.

A comprehensive research on γ-ray and particle radiation interaction parameters of Cerium doped heavy oxide inorganic scintillators

In this study, the interaction cross sections of heavy oxide scintillators, which have a very important place in high energy physics research, with photon and particle radiation were comparatively investigated. In this context, the interaction parameters of six different Ce-doped heavy oxide scintillators were obtained using updated software. The interactions of photons with energies between 1 keV and 100 GeV with scintillators were evaluated in the light of the results produced by the Phy-X/PSD software. In addition to the continuous energy range, calculations were also made on the photon energies emitted with the highest probability of emission from sources 241Am (59.54 keV), 133Ba (356 keV), 22Na (511 and 1280 keV), 137Cs (662 keV) and 152Eu (1460 keV). Additionally, evaluations of energy absorption build-up factors valid under broad beam conditions are also included in this study. Fast neutron absorption cross sections and changes in the range (R) values for heavy particle radiation in the range of 1 keV–20 MeV were also determined with SRIM and ESTAR software. All data obtained depending on energy are explained according to the mass percentages of Lu, Gd, Hf, Y, Al and O elements in the scintillators. The highest interaction cross section for photons was obtained in the Lu2Gd2SiO5 (Ce 0.3%) scintillator (HOS2). The interaction cross section of this scintillator was obtained as 3.115 and 0.042 cm2/g at 0.1 MeV and 10 MeV photon energies, respectively. On the other hand, the highest cross-sections of the fast neutrons were observed in the scintillator (HOS5) containing GdAlO3 (Ce 1.0%) as 0.148 cm−1. This difference in neutron radiation has been explained by calculating the individual attenuation abilities of the elements in the structures. It is hoped that the data obtained will guide researchers working on the detection of different types of radiation.

Enhancement of radiation shielding properties in BaTiO3 added with Bi2O3 at the energy range of 356keV -1333keV

Abstract The investigation on the radiation shielding properties of BaTiO3-xBi2O3 with (x=0, 2, 4, 6, 8 %) ceramic samples has been discussed in this paper. This study targeted especially on the radiation shielding properties such as tenth value layer (TVL) and effective electron density (Neff) by including density of sample as one of the parameters. The prepared ceramic samples radiation shielding properties were quantified with help of radioactive sources Ba133, Na22, Cs137, and Co60 at the energies 356keV, 511keV, 1173keV, 1275keV and 1333keV. The obtained experimental values compared with theoretical values by using Phy-X/PSD software. Obtained results revealed that, attenuation abilities improved due to addition of Bi2O3 at different concentration to BaTiO3 causes the rise in density of ceramic samples from 5.483 to 5.498g/cm3. S1 sample has maximum TVL value found at 10.098cm and sample S4 noticed with lowest value 9.842cm at 1333keV. The maximum Neff value recorded as 2.72 at 1333keV for sample S4 which indicating promising radiation shielding abilities.

Recycled cathode ray tube waste glasses for radiation shielding applications: Role of Na2CO3

The aim of the study is to evaluate the ability of cathode-ray tube funnel waste glasses (CRT-F) to shield photons (gamma and X-ray) and other forms of radiation with rest masses (i.e., neutrons and charged particles) after their Pb content was reclaimed. The lead (Pb) content of cathode-ray tube funnel waste glasses (CRT-F) was reduced using Na2CO3 as the reducing agent CRT-F(Na2CO3). CRT-F and CRT-F(Na2CO3) were produced using the melt and quench processes using the powder of pristine funnel glass from discarded cathode ray tube glass and the reduced glass powder, respectively, as the starting materials. The X-ray fluorescence technique was adopted for determining the chemical composition of CRT-F and CRT-F(Na2CO3) glasses. The parameters relating to the gamma photon, fissile neutron, moderated neutron, slow neutron, and charged radiation (β, H+, He2+, and C6+) attenuation abilities of pristine CRT-F and CRT-F(Na2CO3) were evaluated. The FLUKA simulation code and XCOM were used to estimate the mass attenuation coefficient of the glasses. The stopping power (Sp) and range (R) of β, H+, and He2+ were evaluated by using the NIST data-based calculators (ESTAR for β, PSTAR for H+, and ASTAR for He2+) while Sp and R data for C6+ was determined using SRIM. The cross section for fast, thermal (25 meV), and slow neutrons (0.1–10 meV) was also estimated. The Pb reclamation from the CRT-F drastically increased the half value layer of photons by at least a factor of 4 at 0.1 MeV and by more than 90 % at 10 MeV. The CRT-F interacts more with fissile and thermal neutrons compared to CRT-F(Na2CO3). Although, CRT-F showed a better ability to attenuate all the radiation types considered, both glasses are better absorbers of radiation (especially photons) than some common shields. The reduction of Pb weight in CRT-F resulted in a drastic reduction in the ability of the glass to attenuate radiation; the resulting glass (CRT-F(Na2CO3)) is however, an environmentally safer glass shield.

Fabrication of ZnO/ Bi2O3/PVA coated glass for X-ray detection and measurement

Electrospun ZnO/Bi2O3/PVA-coated glass samples were fabricated using electrospinning method, with varying ZnO molarities (0 M, 5 M, and 7 M) and Bi2O3 weight percentages (wt%) to assess their potential for x-ray detection and measurement. Sample morphology and elemental composition analysis revealed well-distributed nanofiber strands on the glass substrate, with even dispersion of elements within the nanofiber across all samples. The effective atomic number (Zeff) of the sample is consistently enhanced with the addition of Bi2O3 and higher ZnO molarity, where sample with 7 wt% Bi2O3 own a greater Zeff value (41.56–44.12) than sample with 5 wt% Bi2O3 (37.22–40.54). All samples except Sample A0 and B0 exhibited strong absorbance between wavelength range of 360 nm–400 nm. Sample A0 and B0 yielded energy band gaps (Eg) of 2.39 eV and 2.37 eV, respectively, whereby samples with ZnO exhibit energy gaps of Eg = 3.29 eV (Sample A1), Eg = 3.27 eV (Sample A2), Eg = 3.25 eV (Samples B1 and B2). All samples underwent x-ray exposure at various tube voltages (40–60 kVp) to assess their attenuation ability for x-ray detection and measurement. Sample B2 (5 wt% Bi2O3 and 7 M ZnO) exhibited the most favorable linear response, while Sample B1 (5 wt% Bi2O3 and 5 M ZnO) displayed favorable energy dependency. Thus, the electrospun ZnO/Bi2O3/PVA-coated glass with these compositions are proposed as potential dosimetry material due to their favorable linear response and energy dependency characteristics.

Lightweight Fe-doped MnO2@C hollow nanocubes for ultra-broadband microwave absorption

The rational structural design and compositional merits as well as the synergistic coupling effect can break the properties of single material and broaden the microwave absorption band. Herein, the unique lightweight Fe-doped MnO2@C hollow nanocubes are rationally designed and successfully synthesized via a scalable wet chemical process and polydopamine coating followed by high-temperature calcination. By virtue of the unique structure and compositional merits, the as-obtained Fe-doped MnO2@C hollow nanocubes (Fe–MnO2@C-HNBs) displayed notable microwave absorption performance (MAP), simultaneously achieving ultra-broad absorption bandwidth and strong absorption characteristics at a low thickness of 2.3 mm (the reflection loss of −41.02 dB and the effective absorption bandwidth of 5.86 GHz). Surprisingly, the effective absorption bandwidth (RL < −10 dB) could reach up to 8.08 GHz and the minimum reflection loss (RLmin) was −38.20 dB at the thickness of 2.7 mm. The results further confirmed that the excellent microwave attenuation ability of the as-prepared Fe–MnO2@C-HNBs composites benefitted from the special “air@core-shell” structure and multiple heterointerfaces as well as multi-component recombination. These results demonstrated that the as-obtained Fe–MnO2@C-HNBs composites could be attractive candidates for broadband microwave absorption materials.

Electromagnetic wave absorbing biomass kelp derived porous carbon anchored by Fe3O4 nanocomposites

Increasingly serious electromagnetic pollution problems bring the threaten for national defense security and personal health, biomass carbon materials derived absorbers have arouse widespread interest due to their green, easy accessibility, structural diversity, rich functional groups. Herein, biomass kelp derived three-dimension (3D) porous carbon/Fe3O4 (KPC/Fe3O4) nanocomposites were successfully synthesized vis KOH activation as well as in-situ growth of Fe3O4 and following pyrolysis. Attributed to multiple transmission paths for electromagnetic wave from 3D porous structure, dielectric-magnetic synergistic effect, and numerous defects in the kelp-derived carbon with polarization loss caused by heteroatom doping and interfacial polarization, KPC/Fe3O4 nanocomposites possess outstanding impedance matching and extraordinary attenuation ability. In particular, the minimum reflection loss (RLmin) value of KPC/Fe3O4-0.1 nanocomposite reaches −75.02 dB at 10.5 GHz as well as the effective absorption bandwidth (EAB, RL < -10 dB) value achieves 4.83 GHz with a thickness of 2.85 mm. Unique structures and excellent EWA performance demonstrate that KPC/Fe3O4 nanocomposites can serve as potential absorbers for military and civilian fields.

Microwave absorption and electromagnetic properties of ultra-high-strength cementitious materials: Influence of basalt powder and underlying mechanism

The utilization of basalt powder in ultra-high-strength cementitious materials (UHSCMs) holds significant potential for application in mitigating CO2 emissions and reducing electromagnetic pollution. This study investigated the microwave absorption and electromagnetic properties of UHSCMs incorporating basalt powder, with the silica-fume-based mix as a comparison. A comprehensive multi-scale investigation was conducted to gain an in-depth understanding of the electromagnetic properties of UHSCMs. From the results, the UHSCM with basalt powder was demonstrated to possess improved microwave absorption performance, characterized by a mean reflection loss of −8.22 dB and effective bandwidths of 58.3% (<-7.0 dB) and 26.6% (<-10.0 dB). The enhanced performance of this mixture was attributed to its superior impedance-matching capability and microwave attenuation ability. The dielectric loss peaks within frequency ranges of 7.0–8.5 GHz and 10.0–11.5 GHz were caused by the interfacial polarization of macro pores and gel pores, respectively. The natural resonance, exchange resonance, and eddy current effect were the primary mechanisms of the magnetic loss. CaFeSi2O6 particles from basalt powder contributed to the enhanced natural resonance. In addition, basalt powder had the better market potentials and lower environmental impact as a supplementary cementitious material than silica fume for enhancing microwave absorption of UHSCMs. The finding of this study demonstrated the suitability of adopting basalt powder in UHSCM production with improved greenness and electromagnetic properties.

Lightweight titanium dioxide/carbon nanotube composites prepared by atomic layer deposition for broad-band microwave absorption

The microwave absorbing material with appropriate impedance matching and excellent attenuation ability can be applied to resist electromagnetic radiation. In this work, carbon nanotubes were modified by titanium dioxide via the atomic layer deposition method, to prepare lightweight composites with high microwave absorption performance. The impedance matching and attenuation ability of titanium dioxide/carbon nanotube (TiO2/CNT) composites could be precisely controlled by adjusting the number of titanium dioxide deposition cycles. The relationship between the microstructure and microwave absorption performance of the composite was analyzed in detail. When the number of TiO2 deposition cycles was 100, the composite displayed outstanding microwave absorption performance, due to appropriate impedance matching and strong attenuation ability. The maximum effective absorption bandwidth of the composite reached 5.19 GHz (1.6 mm), which almost covered the Ku band. The microwave attenuation mechanism of the composite has also been investigated. This work provided a new idea for fabricating lightweight microwave absorption materials.

Enhancing gamma-ray shielding with Bi2O3-Enriched BTBi glasses: Optimal balance of attenuation and glass transparency

A host glass of barium-magnesium-boro-tellurite (BTBi0) was produced and reinforced with 10, 20, 30, and 40 mol% of Bi2O3 (BTBi1, BTBi2, BTBi3, and BTBi4) to enhance its gamma rays shielding efficiency. The structural, optical, and attenuation properties of the produced BTBi glass series were studied. Penetration of Bi2O3 up to 30 mol% into the proposed host network enriches it with non-bridging oxygens (NBO) units, while the glass containing 40 mol% was enriched with bridging oxygens (BOs) units, which arose as a result of the role of the Bi3+ ion in disrupting the borate network, leading to the BO4⇋BO3 conversion. The conversion role of Bi2O3 was clearly evident in the behavior of the molar volume, oxygen packing density, and packing density. The results of Raman shift showed the formation of the structural units of the boro-tellurite network and BiO6 units within the glass network. The compositional changes brought about by Bi2O3 agreed perfectly with the results of the optical properties of the studied glass. The red shift in optical absorption spectra, the reduction in the optical band gap, and the augmentation of Urbach energy up to 30 mol% of Bi2O3 occurred mainly as a result of the formation of NBOs units. In contrast, at 40 mol% of Bi2O3, the continuation of the red shift, the decrease in the optical band gap, and the increase in the Urbach energy, despite the increase in BOs compared to the NBOs, are attributed to the high polarizability of Bi3+ and the formation of BiO6 units. The transparency of the glass increased to about 85 % with increasing Bi2O3 up to 30 mol%, but decreased to 70 % at 40 mol%. The ability of the considered glasses to attenuate gamma rays was examined using Phy-X/PSD software. The results showed that the attenuation ability improved significantly with increasing Bi2O3 concentrations, where the required thickness to attenuate gamma rays was reduced by 48.505–77.134 % at 40 mol% of Bi2O3. Based on the high attenuation ability and transparency of the studied BTBi glasses, they can be used as a protective shield against gamma rays in nuclear applications that require visual monitoring.

Synthesis of flowerlike vanadium diselenide microspheres for efficient electromagnetic wave absorption

The revelation of MoS2 as an efficient electromagnetic wave (EMW) absorbing material has ratcheted up people’s attention to other transition metal dichalcogenides (TMDs). To date, extensive studies have been conducted on the semiconducting VIB-Group TMDs while research into metallic VB-Group TMDs has been relatively rare. In this work, we successfully fabricated VB-Group VSe2 microspheres through a facile one-step hydrothermal method and used them as EMW absorbers. The flowerlike VSe2 microspheres based on VSe2 nanosheets exhibited a minimum reflection loss of 46.58 dB with an effective absorption bandwidth of 4.86 GHz. The influence of material morphology, microstructure, and dielectric properties on the EMW absorption performance was systematically investigated. The hierarchically layered structure promoted dielectric loss and EMW absorption by means of multiple reflection, interfacial polarization and related relaxation, and enhanced attenuation ability. This work not only demonstrates that VSe2 is potentially a high-efficiency single component EMW absorber, but also provides fresh insights into exploration on the EMW loss mechanisms of the metallic TMD-based absorbing materials.

Large-Scale Experimental Model Of Edge Treatments For Constructed Salt Marshes

Large stretches of Canada’s coastlines are lined with legacy dykes (or levees) to provide protection against coastal flooding and erosion. However, future sea-level rise presents a risk to these structures, which may result in the dykes being under designed when exposed to future water levels and wave conditions. Under certain conditions, these dykes can be augmented with a coastal saltmarsh to create a living dyke, which allows for the existing dyke to be more resilient against sea level rise without the need to retrofit the dyke with a higher crest elevation or larger armour stone. The coastal saltmarsh is able to attenuate storm waves, resulting in lower wave energy at the dyke, while also attracting and retaining sediment to combat coastal erosion. The Living Dyke project in Boundary Bay, Canada is a pilot project being used to test the living dyke concept by placing sediment and planting salt marsh vegetation in the foreshore combined with upgrades to the existing dyke. Kerr Wood Leidal Associates Ltd. prepared a preliminary design which incorporated four different edge treatment features that are to be installed at the offshore edge of a newly constructed salt marsh platform in order to attenuate wave energy and retain the placed sediment before the planted vegetation can be established. The proposed edge treatment features included a natural sand edge, a rounded gravel berm, an oyster-shell filled bag berm, and a brushwood dam. Large scale (full scale for all edge treatment feature tests except for the brushwood dam which was conducted at half-scale) physical model experiments were carried out by the National Research Council of Canada’s Ocean, Coastal and River Engineering Research Centre in their Large Wave-Current Flume to investigate the performance, including stability of the edge treatment features, wave attenuation ability, and stability of the salt marsh platform, of these edge treatment features under varying water level and wave conditions that are present at Boundary Bay.

Dielectric-magnetic synergistic construction of 2D FeCo/Co8FeS8/C composites for efficient electromagnetic wave capture

Nowadays, the issue of electromagnetic pollution has become increasingly prominent, underscoring the critical importance of developing high-performance microwave absorbers. This study put forwards the synthesis process of two-dimensional (2D) FeCo/Co8FeS8/C carbon nanosheets, wherein CoSO4 and FeCl3 serve as inorganic salt templates, and dopamine functions as the carbon source. FeCo alloy nanoparticles and Co8FeS8 nanoparticles are loaded on the surface of the carbon layer. 2D structure forms the conductive network, which proves advantages in establishing efficient electronic channels and minimizing conduction losses. The carbon component increases the dielectric constant of the composite and improves its impedance matching, and the FeCo alloy provides a certain ML. The synergistic effect between these components significantly contributes to the exceptional microwave absorption performance of the composites. Accordingly, the minimum reflection loss (RLmin) of FeCo/Co8FeS8/C composite reaches −47.4 dB, its effective absorption bandwidth (EAB) reaches 5.3 GHz. In particular, CST confirms that radar cross-section reduction value of FeCo/Co8FeS8/C composite can reach 20.2 dB m2 in the range of −90° < phi< 90°, indicating a high microwave attenuation ability. The study introduces a novel strategy for advancing the development of two-dimensional carbon-based absorption materials.

Developed concrete reinforced by waste of lead fishing weights and steel nails as gamma rays and neutrons shields for nuclear power reactors

Wastes of steel nails WSN and wastes of lead fishing weights WLFW were successfully recycled in concrete to enhance its ability to attenuate neutrons and gamma rays. A series of studies on the effect of partially replacing coarse aggregates of concrete with different percentages (5, 10, and 20%) of WSN or WLFW on the density, slump, compressive strength, and attenuation of neutrons and gamma rays were implemented. The compressive strength of WSN-reinforced concrete ranged between 36.2 and 45.2 MPa, while that of WLFW-reinforced concrete ranged between 28.6 and 45.1 MPa. The ability of WSN- or WLFW-reinforced concrete to attenuate neutrons and gamma rays was tested by using two types of neutron energies; slow and total slow neutrons; and three gamma rays energies 661.64, 1173.23, and 1332.51 keV. Slow and total slow neutrons macroscopic cross-section, linear and mass attenuation coefficients of gamma rays, and half value layer for both types of nuclear radiation were obtained. The results showed that there is a significant improvement in the slow and total slow neutron attenuation efficiency of the considered concrete when reinforced by WSN or WLFW. On the other hand, due to the increase in the atomic number and density of both Fe present in WSN and Pb in WLFW, the attenuation ability of the studied gamma ray energies increased. The WLFW-reinforced concrete showed better value in the gamma rays and neutrons attenuation parameters compared to the WSN-reinforced concrete. Hence, the considered concretes reinforced by WSN or WLFW are a distinguished choice as radiation shields in nuclear power reactors, in addition to their adaptability to high concentrations of waste.