Shielding Effect Research Articles

Dual-Network MXene/Polyurethane Composite Foams for Both Stretchable and Compressible Electromagnetic Interference Shielding and Strain Sensors.

Miniaturized and wearable electronic products require electromagnetic interference shielding (EMI) materials with sensing functions to cope with complex application situations. Herein, an effective dual-network structure is designed to fabricate two-dimensional transition metal carbides and nitrides/bacterial cellulose-thermoplastic polyurethane (MXene/BC-TPU) foams with intriguing EMI shielding property and piezoelectric sensing ability under both compressive and tensile strains. Anisotropic MXene/BC aerogels, as conductive networks, with impressive conductivity (1912 S m-1), ultrahigh EMI shielding effectiveness (SE) of 86 dB, and absolute SE up to 63,608 dB cm2 g-1 can be built by directional freezing. Interpenetrated neuro-like TPU network is embedded into the MXene/BC aerogels by controllable coagulation to provide elasticity. Inheriting the elastic TPU network, the light weight MXene/BC-TPU foams show superb elasticity and remarkable fatigue resistance suffering both compressive and tensile strains with a wide strain range (-80-80%). Meanwhile, benefiting from the separated conductive MXene/BC network and the elastic TPU network, the MXene/BC-TPU foams display an outstanding EMI SE (76 dB) with an EMI SE retention of 86.8% after 5000 compression-release cycles and an EMI SE retention of 69.7% after 100 stretch-release cycles, respectively. Furthermore, the MXene/BC-TPU foams reveal stable resistance signal output as piezoresistive sensors in a wide strain range of -80-80%. The highly conductive, stretchable, and compressible MXene/BC-TPU foams are suitable as EMI shielding and motion monitoring materials for wearable electronics.

First-principles calculation of the stopping power of protons in hexagonal boron nitride with different stacking sequences.

The Time-dependent density functional theory was used to calculate stopping power of one and two layers of Hexagonal Boron Nitride (h-BN) with different stacking sequences. The simulation results revealed that stopping power is influenced by collision parameters and electron density, while proton charge state has little effect on stopping power. Additionally, charge transfer and force of protons in h-BN materials were analyzed in detail under different stacking sequences. The calculation results show that although the force on the projectile mainly comes from the target atoms, the limited interaction time allows the projectile to primarily dissipate energy through electron excitation. The influence of the variations in electronic structure due to different stacking structures on the stopping power was investigated. The research results indicate that the dislocation stacking in h-BN, which slightly increases the energy loss, is mainly attributed to the changes in electron density and the role of the impact parameter. This asymmetric stacking structure may have a more pronounced shielding effect on particles. Despite the slight variations in band structures due to different stacking configurations of h-BN, the bandgap widths are roughly consistent, which leads to protons displaying similar energy transfer properties as they pass through bilayer h-BN with varying stackings.&#xD.

High-Durability Cellulose-Based Composite Paper with Superior Electromagnetic Interference Shielding.

Highly efficient electromagnetic interference (EMI) shielding materials are critical for portable hardware and flexible electronics, where mechanical durability often poses challenges. Here, the excellent wear resistance and flexibility of thermoplastic polyurethane are utilized to provide a "protective layer" for EMI equipment. A carbon nanotube/cellulose/thermoplastic polyurethane (CNT/paper/TPU) composite paper with a three-layer structure was prepared using a coating method. Strong hydrogen bonds between CNTs, cellulose, and TPU ensured robust integration. The composite, with a thickness of 0.54 mm and conductivity of 1040 S/m, achieved exceptional EMI shielding effectiveness of 69.0 dB. It demonstrated durability against water, solvents, bending, and friction while maintaining shielding performance. Furthermore, its excellent mechanical properties and fatigue resistance significantly enhance equipment lifespan. Therefore, it is expected that this work will open a simple strategy for developing materials with excellent durable EMI shielding properties.

Computational Analysis of Wind Neighborhood Effects on Buildings: A Comparison Between Closure Models for Turbulence

Determining the neighboring effects of wind is a complex task, as generic approaches are often unable to accurately capture the interactions between buildings and their surrounding environment. For this reason, standard guidelines may be insufficient for determining these effects, making it necessary to rely on wind tunnel testing or numerical simulations through computational fluid dynamics (CFD). This study presents an analysis of the changes in aerodynamic coefficients of the CAARC (Commonwealth Advisory Aeronautical Research Council) building due to the presence of neighboring structures that interfere with wind flow. The neighborhood consists of eight blocks with proportions of 1:1:3. Turbulence was modeled using the Reynolds-Averaged Navier-Stokes (RANS) approach, employing the k-omega and k-omega SST turbulence closure models. A comparative analysis of the results obtained from these two models is presented. The study was conducted by varying the system’s orientation from 0 to 90 degrees in 15-degree intervals. Results show that the perimeter buildings create a shielding effect on the centrally located CAARC building, leading to a reduction in the drag coefficient. Additionally, for some angles, the presence of neighboring structures caused an increase in the torsional and lift coefficients.

The influence of sodium alginate on kaolinite flocculation in presence of metal ions: guidance for green processing

In this study, the responsiveness of Na+, Mg2+, Ca2+ and Al3+ to sodium alginate (SA) and their influence on kaolinite dispersion/flocculation behavior were investigated through rheology and turbidity tests. The effects of metal ions on the interaction between SA and kaolinite were analyzed by zeta potential, fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT). The results showed that Na+ and Mg2+ resulted in a decreasing of the viscosity and modulus of SA solution for they have the electrostatic shielding effect on SA. Ca2+ and Al3+ significantly increased the viscosity and modulus of SA solution because Ca2+ and Al3+ not only have the electrostatic shielding effect on SA but also could form the different network structure complexes. The order of the responsiveness of metal ions and SA sorted by intensity level was: Al3+> Ca2+>Mg2+> Na+. SA has a dispersion effect on kaolinite particles under the background of Na+ and Mg2+, and SA has a flocculation effect on kaolinite particles in the presence of Ca2+ and Al3+. The flocculation efficiency of SA on kaolinite suspension containing Al3+ was much higher than that of SA on kaolinite suspension in the presence of Ca2+. Zeta potential and FTIR results showed that SA could be adsorbed on the kaolinite surface through electrostatic force and hydrogen bond in the presence of Na+ and Mg2+. Microscope observation, XPS and DFT results showed SA could not only form chemical adsorption with Ca2+/Al3+ on the kaolinite surface but also be cross-linked with Ca2+/Al3+ to form a network structure, which could sweep and trap kaolinite particles in suspension. This work has strategic significance for the responsiveness of natural polysaccharide to metal ions and their application in environmental protection of mine wastewater, as well as the clean and circular utilization of water.

Predicting the shield effectiveness of carbon fiber reinforced mortars utilizing metaheuristic algorithms

Predicting the shield effectiveness of carbon fiber reinforced mortars utilizing metaheuristic algorithms

A Laboratory Study of Plasma Charging Inside Lava Tubes on the Lunar Surface

Abstract The electrostatic charging environment inside lunar lava tubes was investigated in laboratory experiments using a glass tube exposed to a simulated solar wind flow. A conducting surface was attached at the entrance of the tube and biased to various negative potentials to study the electron shielding effect on the charging conditions inside the tube. The electrical potential at the bottom of the glass tube was measured using a planar probe. It is shown that the bottom surface potential is positive and increases with the increasing ion beam energy, as well as with the increasing depth inside the tube, as a result of electron Debye shielding at the entrance and along the length of the tube due to the electron thermal motion. It is found that the bottom tube potential does not approach the ion kinetic energy even when the solar wind electrons are nearly fully shielded from entering the tube. We show that ion-generated secondary electrons from the sidewall of the tube partially neutralize the buildup of positive charges at the bottom of the tube. Our results provide insights into the plasma charging environment inside lunar lava tubes that may be used as natural habitats for future human exploration on the surface of the Moon.

Influence of different polymeric materials of implant and attachment on stress distribution in implant-supported overdentures: a three-dimensional finite element study

PurposeInvestigating high performance thermoplastic polymers as substitutes to titanium alloy, in fabrication of implants and attachments to support mandibular overdenture, aiming to overcome stress shielding effect of titanium alloy implants.Aim of studyAssessment of stress distribution in polymeric prosthetic components and bone around polymeric implants, in case of implant-supported mandibular overdenture.Materials and methods3D finite element model was established for mandibular overdenture, supported bilaterally by two implants at canine region, and retained by two ball attachments. Linear static stress analysis was carried out by ANSYS 2020 R1. Three identical models were created with different materials for modeling of prosthetic components (implant body, gingival former, ball attachment and matrix). The Monolithic principle was applied as the same material was used in modelling all the prosthetic components in each model (Titanium alloy grade V, poly-ether-ether-ketone (PEEK) and poly-ether-ketone-ketone (PEKK)). Simultaneous Force application of 60 N was carried out bilaterally at the first molar occlusal surface area using 3 runs (vertical, lateral and oblique).ResultsPEEK and PEKK prosthetic components exhibited the highest total deformation and critical Maximum von Mises stresses values in implant body and gingival former under lateral and oblique loads. The stress values approached the fatigue limit of both polymeric materials presenting low factor of safety (< 1.5). The Peri-implant cortical bone in case of PEEK and PEKK showed nearly double maximum principal stresses compared with the titanium model. Conversely, Maximum von Mises stresses in spongy bone were lower in polymeric models than those of titanium ones. Additionally maximum equivalent strain values in spongy peri-implant bone of polymeric models were also lower than those of titanium model.ConclusionCritical high stresses were induced in implant body and gingival former under oblique or lateral loadings, accordingly, fatigue failure of both PEEK and PEKK polymer prosthetic elements was estimated due to low factor of safety. Both PEEK and PEKK Polymer models offered no advantage over titanium one regarding stress shielding effect, due to low stress and strain values generated at spongy peri-implant bone in polymer models.

Influence of neodymium doping on radiation shielding properties of yttrium lead borotellurite glass system

The need for effective shielding materials has grown as radiation-based technologies have been more widely used. Glasses doped with rare earth elements like neodymium oxide, are promising candidates due to their enhanced radiation attenuation properties. Using Phy-X software, this research examines how neodymium oxide doping affects the shielding properties of yttrium lead borotellurite glass. X-ray diffraction confirmed the amorphous structure, while density measurements showed increased density with neodymium oxide addition. The Phy-X software calculated radiation shielding parameters for gamma energies from 10⁻³ to 10⁵ MeV. The results demonstrate that neodymium oxide improves gamma irradiation attenuation and enhances the glass system's radiation shielding capabilities.

Shielding effectiveness of high-polymer short-staple-based fabric implanted with the metamaterial structure of “split ring resonator”

PurposeElectromagnetic shielding (EMS) fabrics composed of cotton, polyester and other high-polymer short-staple fibers are widely utilized in various fields. However, the inevitable pores in these fabrics lead to the leakage of electromagnetic waves, which severely diminishes the fabric’s shielding effectiveness (SE). To address this issue, this paper proposes the implantation of a metamaterial structure known as the “split ring resonator (SRR)” into the fabric.Design/methodology/approachFirstly, the types and principles of SRRs are analyzed. Through electromagnetic simulation and emulation, the effectiveness of SRRs in dissipating electromagnetic waves is confirmed. By selecting different embroidery methods, various shapes of SRRs are implanted into the fabric. Subsequently, through testing and analysis of sample fabrics embroidered with SRRs, it is concluded that implanting appropriate SRRs into pure cotton fabrics and cotton/polyester/stainless steel-blended EMS fabrics can effectively impart or enhance the SE of these fabrics.FindingsFor pure cotton fabric without inherent SE, the peak SE value can reach over 30 dB within the 6.57 GHz–7 GHz frequency band, and the minimum SE is greater than 10 dB in the 7 GHz–9.99 GHz frequency band. For the cotton/polyester/stainless steel-blended EMS fabric, the improvement in SE across all frequency bands exceeds 10 dB, averaging around 15.6 dB. The circular type SRR demonstrates the most significant improvement in fabric SE. When the substrate is composed of pure cotton or a cotton/polyester/stainless steel blend, the circular SRRs provide an average enhancement of more than 4 dB and 6 dB, respectively, than other shapes. The fewer the holes created by the implantation method, the higher the SE of the fabric after SRR implantation, with the invisible embroidery technique being the most effective. It improves the fabric’s SE by an average of about 2 dB more than flat embroidery and can be up to an average of around 6 dB higher than the backstitch embroidery technique. For every 0.2 cm increase in the size of the SRRs, the average SE increases by about 4 dB, and for every 0.5 cm increase in the spacing between them, the fabric’s SE decreases by an average of more than 2.7 dB.Originality/valueThis paper offers a novel approach to counteract the issue of pores reducing the SE of EMS fabrics and provides a new method for developing lightweight, thin, low-cost and high-performance EMS fabric composite materials.

Flexible 3D‐Printed Cellulosic Constructs for EMI Shielding and Piezoresistive Sensing

AbstractAdvances in materials science and sustainability have positioned cellulose nanofibers (CNFs) as an important nanomaterial for creating complex 3D architectures through 3D printing techniques. However, the inherent limitations of 3D‐printed CNF‐based materials, such as poor electrical conductivity and restricted mechanical flexibility, pose barriers to their application in next‐generation electronics. The research addresses these challenges by integrating CNF‐based 3D printed frameworks with a conductive polymer via a process known as “cold chemical vapor polymerization” (CCVP). The procedure initiates with the direct ink writing (DIW) of the CNF hydrogel, which then undergoes saturation with Fe3+ ions and freeze‐drying to produce ion‐embedded CNF frameworks. Subsequently, interconnected conductive pathways of poly(3,4‐ethylenedioxythiophene) (PEDOT) are generated within these structures using CCVP. This methodology allows for precise customization of electrical conductivity, resulting in the production of highly conductive (546 S m−1) and mechanically flexible (70% compressible) patterned constructs. This advancement is highlighted by the development of grid‐based structures designed for electromagnetic interference (EMI) shields. These innovative shields demonstrate an absorbance of 0.71 and a specific EMI shielding effectiveness of 3406.45 dB cm2 g−1. Furthermore, these aerogels function as highly sensitive piezoresistive sensors, demonstrating the versatility of this sustainable approach for advancing wearable electronics and multifunctional technologies.

The impact of interplanetary magnetic field intensity on the Martian ionosphere

The interplanetary magnetic field (IMF) is one of the important external drivers that controls the Martian-induced magnetosphere and ionosphere. Previous studies have shown that the ion escape process is highly influenced by both the direction and intensity of the IMF. The enhanced IMF may decrease the ion escape rate by inducing a stronger magnetosphere that protects the Martian ionosphere, but the mechanisms have not been investigated thoroughly. Further studies are needed to reveal the response of ionospheric heavy ions to IMF variation as well as the underlying physical mechanism. This study aims to investigate the influence the IMF strength has on the Martian ionosphere. We adopted a multifluid magnetohydrodynamic (MHD) model in this study, which can self-consistently simulate the interaction between solar wind and Mars. By comparing different cases, we analyzed the ionospheric structure on the dayside and near nightside as well as the ion transport process. We aim to obtain a deeper understanding of how the IMF intensity variation impacts the Martian ionosphere and the escape of planetary ions. A three-dimensional multifluid MHD model was used to simulate the interaction between the upstream solar wind and Mars. Four major species in the Martian ionosphere, H^+, O_ O^+, and CO_ are considered in the model, with the chemical reactions and particle collisions included to calculate ion distribution and ion motions. We analyzed three cases where the IMF strength was set to nT ， nT and nT The enhancement of the IMF produces a stronger electromagnetic field in the Martian plasma environment. Both the electric field and magnetic field intensity increase, which provides a shielding effect to the Martian ionosphere, hindering the intrusion of solar wind particles. Thus, less planetary ions are produced by the chemical reactions between the solar wind and the Martian neutral particles, leading to shrinkage of the ionospheric upper boundary. As the IMF strength increases, both the day-to-night plasma transport and the ion outflow decreases. Thus, a more depleted nightside ionosphere is formed, and the tailward ion escape may be weakened, decreasing the global ion escape rate. Moreover, the strong crustal fields in the southern hemisphere enhance the electromagnetic field on the southern dayside, which withstand the penetration of solar wind plasma more effectively, resulting in asymmetry structures in the ionosphere.

Multi-scale fracture characterization method for transitional shale reservoir based on post-stack multi-attribute ant-tracking fusion and pre-stack wide-azimuth gathers AVAZ analysis

Transitional shale gas represents a significant domain for exploration in the oil and gas sector. The distribution area is extensive, and the resource potential is significant, representing approximately 25% of China's total shale gas resources. Approaches for predicting reservoir fractures using seismic attributes has been well-established. Seismic attributes are frequently constrained by elements including the frequency and resolution of seismic data. The characteristics of transitional shale reservoirs, including complex lithological combinations, frequent changes in lithology, low resolution and variable frequency of seismic data, as well as the presence of strong reflection shielding in coal seams, significantly influence fracture prediction. The use of a single seismic attribute technique presents challenges in delivering a thorough and precise prediction of fractures within transitional reservoirs. This study extracts discontinuity information of large fractures, fine fractures, and fractures obscured by strong reflections from coal seams using variance attributes, amplitude contrast attributes, and the amplitude of diffracted waves, respectively. The discontinuity features obtained from the three methods are monitored through an ant-tracking technique and integrated. Fractures in the work area are methodically described. The near-offset Rüger formula method is utilized to analyze the pre-stack wide-azimuth gathers. Anisotropic gradients and anisotropic directions have been derived. The results of the fracture prediction are analyzed and validated. A novel and reliable methodology, designed specifically for the challenges of transitional shale reservoirs, has been developed for combined pre-stack and post-stack seismic multi-scale fracture prediction. The robust reflection shielding effect of the coal seam has been effectively eliminated. The characterization of fractures in transitional shale reservoirs has been enhanced.

Influence of elevated temperature exposure on the residual compressive strength and radiation shielding efficiency of ordinary concrete incorporating granodiorite and ceramic powders

This research investigates the potential of utilizing types of construction waste as partial cement replacements within concrete formulations. Notably, granodiorite and ceramic powders were introduced at varying substitution ratios. The impact of these waste materials on the compressive strength and radiation shielding effectiveness of traditional concrete was evaluated under both ambient and elevated temperature conditions. Additionally, several microstructural tests like X-ray diffraction (XRD), Thermogravimetric analysis (TGA), and Energy dispersive X-ray (EDX) were conducted to assess the influence of using the optimal replacement ratios of the investigated waste powders on the studied properties of concrete. Results revealed a substantial improvement in the investigated properties of the concrete. Remarkably, a 7% substitution with waste granodiorite powder (WGDP) yielded the optimal mix for compressive strength, exhibiting increases of 24.7%, 26.1%, 22%, and 28% at room temperature, 400 °C, 600 °C, and 800 °C, respectively. Likewise, a 7% replacement with waste ceramic powder (WCP) exhibited quantifiable improvements in compressive strength, with approximately 23.1%, 23.5%, 25.6%, and 32.6% at room temperature, 400 °C, 600 °C, and 800 °C, respectively. For microstructure analysis, XRD analysis confirmed enhanced pozzolanic activity with reduced portlandite and increased calcium silicate hydrate (CSH) formation for the optimal WGDP and WCP mixes compared to the control mix. TGA analysis revealed higher CSH decomposition in modified mixes, indicating greater pozzolanic reaction. Furthermore, density and EDX analyses showed denser microstructures in waste powders-incorporated mixes due to finer particle packing and secondary hydration effect. The radiation shielding investigation show that the optimum WCP mix (C7) enhances the attenuation capability of concrete. The optimum WGP mix (GD7) also contributes positively to attenuation, though to a lesser extent than C7. Ordinary concrete (CO) exhibits the lowest LAC, indicating its baseline performance in linear attenuation. Thus, the studied CM-concrete samples provide the best protection against fast neutrons which pave the way for the utilization of industrial waste, especially ceramic and granodiorite waste, in enhancing the properties of concrete towards radiation shielding against gamma rays and neutrons.

Enhancing Zn Deposition Reversibility on MXene Current Collectors by Forming ZnF2-Containing Solid-Electrolyte Interphase for Anode-Free Zinc Metal Batteries.

Anode-free aqueous zinc metal batteries (AZMBs) offer significant potential for energy storage due to their low cost and environmental benefits. Ti3C2Tx MXene provides several advantages over traditional metallic current collectors like Cu and Ti, including better Zn plating affinity, lightweight, and flexibility. However, self-freestanding MXene current collectors in AZMBs remain underexplored, likely due to challenges with Zn deposition reversibility. This study investigates the combination of a Ti3C2Tx self-freestanding film with advanced electrolyte engineering, specifically examining the effects of Li-salt and propylene carbonate (PC) as additives on Zn plating reversibility. While using Li+ ions as an additive alone facilitates uniform Zn deposition on bulk metals through the electrostatic shielding effect, the addition of Li-salt negatively impacts Zn plating uniformity on Ti3C2Tx. Meanwhile, using PC additive alone forms an organic SEI layer on Ti3C2Tx and causes Zn agglomeration. The use of both additives together results in a ZnF2-containing hybrid SEI layer with improved interfacial kinetics, promoting more uniform Zn deposition. This approach achieves an average Coulombic efficiency (CE) of 96.8% over 150 cycles (a maximum CE of 97.8%). The study highlights the strategic difference in electrolyte design, emphasizing the need for tailored approaches to optimize Zn deposition on MXenes, contrasting with traditional metallic current collectors.

The effect of heavy metals on the radiation shielding capabilities of borated polyethylene: a Geant4 study

Abstract Research has increasingly focused on polymers for radiation shielding in medical and industrial applications due to their beneficial properties. Polyethylene, a common polymer, is extensively used as a neutron shield in radiation-related environments, particularly in hospitals. Recently, borated polyethylene-created by combining polyethylene with 5% boron by weight-has been employed in hospital doors due to its exceptional durability across a wide temperature range and its effective neutron shielding capabilities. Hospital doors must protect against radiation leakage that could endanger patients and staff while also being lightweight, resistant to moisture and chemicals, sound-absorbent, and flexible during manufacturing. Borated polyethylene meets all these criteria, leading many manufacturers to produce hospital doors from borated high-density polyethylene (BHDPE). In this study, the shielding effectiveness of borated polyethylene, enhanced with 5% of heavy metals such as iron, bismuth, and tungsten, was theoretically analyzed using Geant4 against photons and neutrons with energies ranging from 10 keV to 20 MeV. The results indicated that iron-borated high-density polyethylene (Fe-BHDPE) offers the best neutron shielding, followed by tungsten-borated high-density polyethylene (W-BHDPE) and bismuth-borated high-density polyethylene (Bi-HDPE). For photon shielding, Bi-HDPE performed the best. The choice of metal and its proportion in radiation protection doors should be tailored to the specific type of radiation present in the facility, considering potential interactions, surrounding conditions, scattering effects, and any secondary particles that may be produced.

Ocean wave-driven covalent organic framework/ZnO heterostructure composites for piezocatalytic uranium extraction from seawater

Piezoelectric catalysis possesses the potential to convert ocean wave energy into and holds broad prospects for extracting uranium from seawater. Herein, the Z-type ZnO@COF heterostructure composite with excellent piezoelectric properties was synthesized through in situ growth of covalent organic frameworks (COFs) on the surface of ZnO and used for efficient uranium extraction. The designed COFs shell enables ZnO with stability, abundant active sites and high-speed electron transport channels. Meanwhile, the interface electric field established in the heterojunctions stimulates electron transfer from COFs to ZnO, which break the edge shielding effect of the ZnO’s metallic state. Additionally, the polarization of ZnO is enhanced by heterogeneous engineering, which ensures the excellent piezocatalytic performance. As a result, ZnO@COF achieves an ultra-high efficiency of 7.56 mg g−1 d−1 for uranium extraction from natural seawater driven by waves. In this work, we open an avenue for developing efficient catalysts for uranium extraction from seawater.

Experimental and GEANT4 simulated FEPE of NaI(Tl) detector for linear sources.

The current study investigated the geometry, design and solid angle impacts on full energy peak efficiency (FEPE) of NaI(Tl) detectors for a line source. A line source is fabricated using99mTc solution filled in a borosilicate glass tube of inner diameter 3 mm, tube wall thickness 2.5 mm and length 12.7 cm. The FEPE is measured for the fabricated linear source using 2″×2″ NaI(Tl) cylindrical detector at various source-detector distances. The experimental setup is simulated in GEANT4 and the computed FEPE values are compared with experimental values. The absolute error of 5% is observed between computed and measured FEPE values. Utilizing the advantages of MC simulations, the impact of numerous source parameters such as source length, diameter, source-detector distance, glass tube thickness and lead shield effects on FEPE are investigated to optimize the fabrication process of linear sources. A case study for current investigation has been analyzed by considering absolute FEPE of the NaI(Tl) system for a syringe filled with radioactive solution. This study provides an insight for the fabrication of standard linear sources by analyzing different source parameters and hence, may serve as a guideline to prepare standard linear sources for the calibration of radiation detectors.

MXene Nanoribbon Aerogel-Based Gradient Conductivity Electromagnetic Interference Shields with Unprecedented Combination of High Green Index and Shielding Effectiveness.

The desire to reduce secondary pollution from shielded electronics devices demands electromagnetic interference (EMI) shields with high green index (GI), which is the ratio of absorbance over reflectance. Achieving high GI values simultaneously with high shielding effectiveness (SE) over 50dB is a serious unresolved challenge. Reducing the impedance mismatch between the shield and free space is the key to reducing the reflection of incoming radiation and enabling more penetration into the body of the shield for absorption. Here a sandwich structure with gradient conductivity is introduced that achieves a combination of high GI (≈2) and SE (70dB). The top layer deliberately uses an aerogel of low conductivity MXene nanoribbon in PEDOT:PSS polymer to boost the GI. The aerogel also reduces the permittivity of the shield, as another way to reduce the impedance mismatch for a nonmagnetic material. The bottom layer consists of a MXene nanosheet-polymer with its high metal-like conductivity to provide high SE. This successful demonstration is expected to lead to other novel ways to create conductivity gradient EMI shields.

Ballistic and Electromagnetic Shielding Properties of Epoxy Resin Reinforced with Carbon Black and Jute Fabric

This study explores the development of a multifunctional composite material by incorporating carbon black (CB) into an epoxy matrix reinforced with 30 vol.% jute fabric. The objective was to evaluate the impact of CB on the composite’s tensile properties, ballistic performance, and electromagnetic shielding effectiveness (SE) within the X-band frequency range (8.2–12.4 GHz). The epoxy composite with 30 vol.% jute and 5 vol.% CB (EJ30/CB5) exhibited 15% improvements in its tensile strength and elastic modulus compared to the epoxy composite with 30 vol.% jute (EJ30) only. Ballistics tests indicated no significant increases in absorbed energy or limit velocity, which may be attributed to the structural rigidity introduced by the CB. An electromagnetic shielding analysis revealed that the CB addition significantly enhanced the SE from ~2 dB in neat epoxy to 5–8 dB in EJ30/CB5, with absorption emerging as the primary shielding mechanism. The findings highlight the potential of CB- and jute-reinforced epoxy composites for applications requiring both mechanical robustness and electromagnetic interference shielding.