Protective Shield Research Articles

Enhancing Li‐ion Battery Performance through the Integration of Si@TiO2 Core‐Shell Nanoparticles with Natural Graphite

AbstractIn this study, Si@TiO2 core‐shell nanoparticles are synthesized using the peptization technique, resulting in a thin and uniform TiO2 coating layer over silicon nanoparticles. This coating layer serves the purpose of controlling the structural degradation of the silicon nanoparticles. These core‐shell nanoparticles are then reinforced into the natural graphite with the potential to be used as a composite anode material (Graphite/Si@TiO2) for Li‐ion batteries. The developed composite material exhibits an initial specific capacity of ≈675 mAh/g at 0.5 A/g, and after 100 cycles it retains the capacity of 75 %. Compared with Graphite/Si composite anode, the developed composite anode material shows improved cyclic stability. The pre‐and post‐cycling morphological analysis of Graphite/Si and Graphite/Si@TiO2 composite anode reveals the degradation behavior. It is assumed that the TiO2 coating provides a protective shield for the silicon particles, preventing their interaction with the electrolyte and causing less material to deposit over the anode surface. Electrochemical Impedance Spectroscopy (EIS) analysis supports these findings, with the Graphite/Si composite anode exhibiting higher resistance than the Graphite/Si@TiO2 anode. In conclusion, the study demonstrates the potential of using Si@TiO2 core‐shell nanoparticles as a reinforcing agent for natural graphite to develop high‐performance composite anode material for Li‐ion batteries.

Obsidian Use in Archaeology: A New Insights from Ethnoarchaeological Perspective in Lake Eyasi Basin, Northern Tanzania

Obsidian, a material of enduring archaeological fascination, has been the research focus due to its diverse applications within ancient societies. Its presence at archaeological sites has led scholars to attribute various uses to it, particularly during the Middle and Later Stone Age. This study was conducted to shed light on the social-cultural and symbolic utilization of obsidian in the Lake Eyasi Basin, revealing its intricate role in early and contemporary cultures. The investigation occurred in Mang’ola ward, Karatu District, and Olpiro village within the Ngorongoro Conservation Area (NCA) in the Arusha Region. Ethnographic data and direct observations were conducted on the Datoga people of Lake Eyasi Basin, with participants deliberately selected from diverse age groups. The research uncovered the multifaceted uses of obsidian, revealing that it serves as a protective shield against bad omens and evil spirits, and wards off misfortune.

Use of melt blending to synthesize wood plastic composites containing modified steel slag: a study

ABSTRACT .The novel modified steel slag/wood-plastic composites were innovatively prepared by melt blending with melt pressure 4.8 MPa ascribed to simpler operation. The addition of modified steel slag could be grafted on the molecular chain of polyethylene and wood powder using melt blending, producing chemical correlations. Their higher flexural strengths in the range of 24.78~32.35 MPa in accordance with GB/T 24137-2009 were used as indoor and outdoor decorative panels. Especially, the wood-plastic composite with 16 wt.% modified steel slag possessed the most optimal tensile strength and flexural strength achieving 17.36 MPa and 32.35 MPa which increased by 16.1% and 9.1% compared with talc powder/wood-plastic composites, respectively. Moreover, modified steel slag containing aluminum oxide, silicon dioxide, magnesium oxide and phosphorus pentoxide combined with residual substances of polyethylene and wood powder, resulting in a rapidly condensed form as a protective shield during combustion, increasing char yields as well as heat resistance.

Relationships between Sustainable Operations and the Resilience of SMEs

In the 21st century, the primary concerns within our society and economic framework revolve around securing a sustainable future and ensuring our future prospects. The crises witnessed in recent years have both introduced new challenges and revived existing difficulties. The crucial question emerges: can societies and economies demonstrate the resilience necessary to avert impending dangers during such circumstances? This consideration holds particular significance for small and medium-sized enterprises (SMEs) operating in the global economy. SMEs play a vital role in national economies, and their importance is even more pronounced within our national societies. Addressing threats and challenges in the SME sector proves to be more challenging due to their compact size, which lacks the protective shield against various environmental impacts enjoyed by larger enterprises with their greater size and capabilities. On the other hand, due to their smaller size, SMEs may be able to overcome these obstacles more successfully than large enterprises by using the appropriate tools and investing in opportunities. The aim of this article is to investigate to what extent environmental protection investments and other sustainability-related developments increase the resilience of SMEs. In connection with the above mentioned, it was investigated how the combination of marketing communication and sustainability goals, and how appropriate communication of sustainability, contributes to increasing the resilience of Hungarian SMEs. The analysis is based on a grouping of 266 small and medium-sized enterprises using the variables created based on the literature review and expert interviews.

Optical UV–visible, Raman spectroscopy, and gamma radiation shielding properties of borate glass systems; B2O3 + Na2O + Al2O3 / MgO/ Li2O

Three borate glass systems with chemical formula 65 B2O3 + 30 Na2O + 5 (x) wt%; x = Al2O3, MgO, and Li2O were fabricated by the common melting-annealing method and coded as BNAl, BNMg, and BNLi, respectively. XRD pattern revealed the non-crystalline form and the glassy states of the prepared samples. UV-optical absorption spectra showed UV cutoff peaks in the range 320–340 nm and optical energy gap (Eopt) by Tauc’s model (ETauc’s) and ASF method (EASF) revealed quite similar values ranged from 2.60 to 3 eV before irradiation and 2.23 to 2.60 eV after 20 kGy of gamma irradiation. Raman spectra show three detectable regions at; (i) 250–600 cm−1, (ii) 500–1000 cm−1 and (iii) 1000–2000 cm−1 correlated to different borate forms. Many radiation shielding parameters were theoretically calculated using Phy-X/PSD and simulated via Monte Carlo code (MCNP-5) in photon energy range (0.015–15 MeV). Mass attenuation coefficient (MAC), linear gamma attenuation coefficient (LAC), effective atomic number (Zeff), fast neutron macroscopic cross section (∑R), exposure buildup factor (EBF) and energy absorption buildup factor (EABF) at various penetration depths PD, as well as half (HVL) and tenth value layers (TVL) and mean free path (MFP) were also estimated. The shielding parameters showed the order of (MAC, LAC)BNAl > (MAC,LAC)BNMg > (MAC, LAC)BNLi. The stability of the glasses optical, and structural properties against gamma irradiation indicate the capable use of the glasses for radiation shielding applications specially Al2O3 glass with the heaviest atomic weight and the highest capacity for radiation shielding protection.

Phytoestrogen: A protective shield for post-menopausal symptoms and breast cancer risk

Menopause is a physiological unavoidable condition in women’s life which leads to vasomotor, psychological, urogenital and chronic diseases collectively termed as post-menopausal symptoms (PMS). Hormone replacement therapy (HRT) is conventional line of treatment for treating PMS in which estrogens replacement is major choice for better therapeutic efficacy against symptoms like hot flushes, osteoporosis, hormonal balances, insomnia, obesity etc. However, estrogen is reported risk factor for breast cancer. The review discusses Ayurveda based strategies for management of PMS with phytoestrogen herbs, diet, lifestyle modification, de-addiction measures, yoga, aroma therapies etc. supported by evidence-based documentation.Herbs namely Dhanyaka (Coriander sativum), Manjishtha (Rubia cordifolia L), Chandana (Santalum album L), Ashwagandha (Withania somnifera L. Dunal), Jatamansi (Nardostachys jatamansi DC), Shatavari (Asparagus racemosus L), Kumari (Aloe vera L), Yashtimadhu (Glycyrrhiza glabra L), Haridra (Curcuma longa L), Triphala (Combination of fruits of Haritaki, Bibhitak, Amalaki in the proportion 1:2:4), Gokshura (Tribulus terrestris L), Arjuna (Terminalia Arjuna L.), Guduchi (Tinospora cordifolia L.), Ela (Elettaria cardamomum L), Narikela (Coccus nucifera L), Masha (Phaseolus vulgaris L), Mudga (Vigna radiata L). Shunthi (Zinziber officinale Roxb), Methika (Trigonella foenumgraecum L), Tila (Sesamum indicum L) are the natural sources of phytoestrogens. Phytoestrogen don’t exert side effects like synthetic estrogen molecules. These herbs are useful for management of various symptoms of PMS. Having anti-cancer potential against breast carcinoma these are useful for prevention of risk of breast cancer.

Elevated concentrations of polymyxin B elicit a biofilm-specific resistance mechanism in Vibrio cholerae

Vibrio cholerae can form biofilms in the aquatic environment and in the human intestine, facilitating the release of hyper-infectious aggregates. Due to the increasing antibiotic resistance, alternatives need to be found. One of these alternatives is antimicrobial peptides, including polymyxin B (PmB). In this study, we first investigated the resistance of V. cholerae O1 El Tor strain A1552 to various antimicrobials under aerobic and anaerobic conditions. An increased resistance to PmB is observed in anaerobiosis, with a 3-fold increase in the dose required for 50 % growth inhibition. We then studied the impact of the PmB on the formation and the degradation of V. cholerae biofilms to PmB. Our results show that PmB affects more efficiently biofilm formation under anaerobic conditions. On the other hand, preformed biofilms are susceptible to degradation by PmB at concentrations close to the minimal inhibitory concentration. At higher concentrations, we observe an opacification of the biofilm structures within 20 min post-treatment, suggesting a densification of the structure. This densification does not seem to result from the overexpression of matrix genes but rather from DNA release through massive cell lysis, likely forming a protective shield that limits the penetration of the PmB into the biofilm.

Decoherence-free-subspace-based deterministic conversions for entangled states with heralded robust-fidelity quantum gates.

The decoherence-free subspace (DFS) serves as a protective shield against certain types of environmental noise, allowing the system to remain coherent for extended periods of time. In this paper, we propose two protocols, i.e., one converts two-logic-qubit Knill-Laflamme-Milburn (KLM) state to two-logic-qubit Bell states, and the other converts three-logic-qubit KLM state to three-logic-qubit Greenberger-Horne-Zeilinger states, through cavity-assisted interaction in DFS. Especially, our innovative protocols achieve their objectives in a heralded way, thus enhancing experimental accessibility. Moreover, single photon detectors are incorporated into the setup, which can predict potential failures and ensure seamless interaction between the nitrogen-vacancy center and photons. Rigorous analyses and evaluations of two schemes demonstrate their abilities to achieve near-unit fidelities in principle and exceptional efficiencies. Further, our protocols offer progressive solutions to the challenges posed by decoherence, providing a pathway towards practical quantum technologies.

Investigation of carbon nanotube sheet for lunar dust shielding

Carbon nanotubes (CNT) sheet is a new type of nonwoven fabric that is being evaluated for different applications. This article presents the first friction-based investigation of the use of CNT sheet as a dust shield. The focus application is for shielding future machinery on the moon from lunar dust. Lunar dust is strongly abrasive; it adheres to all surfaces and causes wear. The absence of an atmosphere and water on the moon, along with its low gravity, and electrostatic adhesion exacerbates the issue of lunar dust, which affects all surfaces, including machinery and human apparel. Friction testing was performed to represent the effect of abrasion occurring on a garment surface while astronauts are working on the moon. The coefficients of static and sliding friction between two CNT sheets, held against each other by a weight, were 0.6 and 0.45, respectively. The presence of lunar regolith simulant reduced the friction coefficients between the two CNT sheets by 33% and 22% for static and sliding friction, respectively. The dust in the sheets was easily cleaned with dry wiping and compressed air, showing no requirement to use water for cleaning in space applications. However, the CNT sheets experienced wear after repeated friction tests. The CNT sheets passed the flammability test standards ASTM D6413/D6413M-15 and NPFA 1971 for applications under extreme heat conditions. Thus, CNT sheet can be considered as a multi-functional material for lunar applications, with shielding protection against dust and electromagnetic waves, and resistance to high temperatures.

Effect of Gonadal Protection on Image Quality in Frontal Hip Radiography

In recent years, there has been a growing movement in Western countries toward the abolition of gonadal protection during radiography. The reasons for this recommendation are that there are few reports of increased risk of genetic effects, that the ovarian dose is not due to direct X-rays but due to internally scattered X-rays that cannot be shielded, and that the presence of gonadal protection may adversely affect the automatic exposure control mechanism and may mask important findings. In addition, the gonadal protection is a large high absorber of X-rays, and its presence in the irradiation field may have some effect on image quality, but the effect of the gonadal protection on image quality has not been clarified. In addition, after the abolition of gonadal protection, the optimal irradiation field setting is expected to become even more important to avoid unnecessary exposure. In this study, we investigated the effect of gonadal protection on image quality in frontal hip radiographs of adults with different radiation qualities and clarified the image quality under conditions in which the irradiation field is appropriately narrowed. Frontal hip radiographs were taken using a human phantom as the subject, and the image quality of the femoral head was evaluated. Two irradiation fields were used: (a) 14×17 inch field and (b) an appropriate field (11.6×15 inch) that does not impair the reference line and image information necessary for reading hip joint images. The imaging tube voltage was set at 70 kV, and conditions for adding a copper filter were also considered. The incident surface air kerma was set to 1.25 mGy. The incident surface dose at this time was sufficiently lower than the diagnostic reference level (2.5 mGy) in Japan and was judged to be appropriate for imaging using an indirect conversion flat panel detector. The image quality evaluation item was the signal difference to noise ratio (SdNR) including scatterers. The SdNR decreased by 4.6% when a gonadal shield was placed, indicating that the gonadal shield reduced image quality. When the irradiation field size was appropriately narrowed down, SdNR slightly increased or decreased depending on the quality of the imaging material, but the change was small compared to the change in SdNR with and without the gonadal protection shield. The results of this study confirm that the elimination of gonadal protection in hip radiography has significant advantages, such as reducing unnecessary X-ray exposure while ensuring image quality, when the irradiation field is set appropriately.

Immuno-surveillance and protection of the human cochlea.

Despite its location near infection-prone areas, the human inner ear demonstrates remarkable resilience. This suggests that there are inherent instruments deterring the invasion and spread of pathogens into the inner ear. Here, we combined high-resolution light microscopy, super-resolution immunohistochemistry (SR-SIM) and synchrotron phase contrast imaging (SR-PCI) to identify the protection and barrier systems in the various parts of the human inner ear, focusing on the lateral wall, spiral ganglion, and endolymphatic sac. Light microscopy was conducted on mid-modiolar, semi-thin sections, after direct glutaraldehyde/osmium tetroxide fixation. The tonotopic locations were estimated using SR-PCI and 3D reconstruction in cadaveric specimens. The sections were analyzed for leucocyte and macrophage activity, and the results were correlated with immunohistochemistry using confocal microscopy and SR-SIM. Light microscopy revealed unprecedented preservation of cell anatomy and several macrophage-like cells that were localized in the cochlea. Immunohistochemistry demonstrated IBA1 cells frequently co-expressing MHC II in the spiral ganglion, nerve fibers, lateral wall, spiral limbus, and tympanic covering layer at all cochlear turns as well as in the endolymphatic sac. RNAscope assays revealed extensive expression of fractalkine gene transcripts in type I spiral ganglion cells. CD4 and CD8 cells occasionally surrounded blood vessels in the modiolus and lateral wall. TMEM119 and P2Y12 were not expressed, indicating that the cells labeled with IBA1 were not microglia. The round window niche, compact basilar membrane, and secondary spiral lamina may form protective shields in the cochlear base. The results suggest that the human cochlea is surveilled by dwelling and circulating immune cells. Resident and blood-borne macrophages may initiate protective immune responses via chemokine signaling in the lateral wall, spiral lamina, and spiral ganglion at different frequency locations. Synchrotron imaging revealed intriguing protective barriers in the base of the cochlea. The role of the endolymphatic sac in human inner ear innate and adaptive immunity is discussed.

Understanding cognitive and language development in refugees: Evidence from displaced syrian children in Turkey

The present study introduces systematic data on the cognitive and linguistic abilities of refugee children. We tested 9–10 year-old Syrian refugee children (N = 25) on their cognitive abilities (i.e., working memory, shifting, inhibitory control, and fluid intelligence) and vocabulary knowledge in Arabic and Turkish. We compared their performance to two non-refugee control groups with low socioeconomic status, matched on age and mother’s education: Arabic-Turkish bilinguals (N = 29) and Turkish monolinguals (N = 19). Refugee children lagged behind both non-refugee groups in the fluid intelligence task. Compared to their bilingual peers, they showed poorer performance in working memory and shifting tasks. On the other hand, these scores matched their monolingual peers, with only slower performance in the shifting task. Greater exposure to trauma and poverty were predictors for lower scores in refugee children’s cognitive tasks. On the language tests, refugee children exhibited a smaller Turkish vocabulary size compared to both non-refugee controls. Trauma exposure, poverty and kindergarten attendance factors were significant predictors for this difference. As for the Arabic language skills, Syrian children outperformed their bilingual peers in Arabic. Although Syrian children displayed a more balanced bilingual profile, their performance in their dominant language (Arabic) was poorer than the bilingual control group’s performance in their dominant language (Turkish). Overall, the results suggest that refugee children’s working memory, shifting and fluid intelligence abilities, as well as mother tongue development, were negatively affected by forced displacement, but they were able to develop Turkish vocabulary skills and match Turkish monolinguals on both working memory and shifting abilities. This is the first piece of evidence suggesting that while being a refugee has adverse effects on children’s cognitive and linguistic development, holding bilingual status may actually create a protective shield in some cognitive abilities for disadvantaged refugee children.

Evaluating the Effectiveness of Tellurium-Molybdenum Oxide Glass Systems for Radiation Shielding Protection

The present investigation examined TeO2–MeO3 glasses with different compositions for their ability to absorb γ-rays using the Phy-X and FLUKA Code, respectively. The study covered energies ranging from 0.015 to 15 MeV, where several parameters such as effective atomic number (Zeff), free path mean (GMFP), mass attenuation coefficient (GMAC), macroscopic cross-section (GLAC), and half-value levels were analyzed (GHVL). Glass composite composed of 80% TeO2 and 20% MoO3 was found to have the lowest GLAC content among the tested samples. GHVL = 0.055 cm was the half-value of the 80TeO2–20MoO3 glasses when they were subjected to 80 keV gamma-rays. It is anticipated that the GMFP of the investigated materials ranges from 0.004 to 0.005 cm when subjected to 100 keV gamma-rays. It was said that the increase in Zeff may be attributed to an increased quantity of electrons that were accessible for interaction with photons, resulting in a decreased probability of gamma rays passing through the shielding material. The cumulative impact of these findings demonstrates that specific glass compositions, particularly those that include Tellurium, have the potential to be used as excellent radiation shielding materials. These materials are becoming more important for providing efficient radiation protection in various industries and applications, including medical imaging, nuclear power, and space exploration.

Enhanced far infrared emissivity, UV protection and near-infrared shielding of polypropylene composites via incorporation of natural mineral for functional fabric development

Far infrared radiation in the range of 4–20 µm has been showed to have biological and health benefits to the human body. Therefore, incorporating far-infrared emissivity additives into polymers and/or fabrics hold promise for the development of functional textiles. In this study, we incorporated nine types of natural minerals into polypropylene (PP) film and examined their properties to identify potential candidates for functional textiles and apparels. The addition of 2% mineral powders into PP film increased the far-infrared emissivity (5–14 µm) by 7.65%-14.48%. The improvement in far-infrared emissivity within the range of 5–14 µm, which overlaps with the peak range of human skin radiation at 8–14 µm, results in increased absorption efficiency, and have the potential to enhance thermal and biological effects. Moreover, the incorporation of mineral powders in PP films exhibited favorable ultraviolet (UV) protection and near-infrared (NIR) shielding properties. Two films, specifically those containing red ochre and hematite, demonstrated excellent UV protection with a UPF rating of 50+ and blocked 99.92% and 98.73% of UV radiation, respectively. Additionally, they showed 95.2% and 93.2% NIR shielding properties, compared to 54.1% NIR shielding properties of PP blank films. The UV protection and NIR shielding properties offered additional advantages for the utilization of polymer composite with additives in the development of sportswear and other outdoor garments. The incorporation of minerals could absorb near-IR radiation and re-emit them at longer wavelength in the mid-IR region. Furthermore, the incorporation of minerals significantly improved the heat retention of PP films under same heat radiation treatment. Notably, films with red ochre and hematite exhibited a dramatic temperature increase, reaching 2.5 and 3.2 times the temperature increase of PP films under same heat radiation treatment, respectively (46.8 °C and 59.9 °C higher than the temperature increase of 20.9 °C in the PP film). Films with additives also demonstrated lower thermal effusivity than PP blank films, indicating superior heat insulation properties. Therefore, polypropylene films with mineral additives, particularly those containing red ochre and hematite, showed remarkable heat capacity, UV-protection, NIR-shielding properties and enhanced far infrared emissivity, making them promising candidates for the development of functional textiles.

Multi-objective decision tool for the assessment of co-located wave-wind offshore floating energy parks

This study explores the benefits of co-locating wave-wind offshore energy parks. It focuses on the leeward effects of hypothetical wave energy converter (WEC) arrays deployed offshore Viana do Castelo, Portugal, and their synergies with the WindFloat Atlantic wind farm. Wave propagation through arrays of CECO WECs and their near-field effects were simulated using SNL-SWAN model. Furthermore, a multi-objective function to evaluate and choose between WEC arrays was defined. The analysis considered a wave height reduction area index, the q-factor and a new wave energy park layout assessment index (WLA). The effectiveness of arrays was dependent on incident wave direction, layouts with larger spacing achieved higher q-factors, while lower spacing provided better shield protection. The WLA, which considers both power absorption and wave height reduction, was introduced as a decision-making tool. The results also showed that some arrangements could increase accessibility to the turbines by circa 22%, representing about 1957 h/year added to the weather window for maintenance and operation of the park. In summary, this study provides a comprehensive analysis and a decision-making strategy for determining the optimal positioning of WEC arrays, contributing to the advancement of renewable energy technologies, promoting sustainable and efficient utilization of wave and wind resources.

Bio-Based Alkali Lignin Cooperative Systems for Improving the Flame Retardant and Mechanical Properties of Rigid Polyurethane Foam.

Lignin was utilized as an environmentally friendly synergistic agent to augment the fire resistance and mechanical characteristics of rigid polyurethane foam (PUF)/melamine-formaldehyde resin ammonium polyphosphate (MFAPP). The incorporation of lignin significantly enhanced the charring capability and flame retardancy of PUF/MFAPP. Specifically, PUF/MFAPP12/A-lignin3 exhibited a charring residue of 23.1% at 800 °C, accompanied by an increase in the limiting oxygen index (LOI) to 23.1%, resulting in a UL-94 V-0 rating. The cone calorimeter test (CCT) revealed that the peak heat release rate (PHRR), total heat release (THR), smoke production rate (SPR), and total smoke production (TSP) values of PUF/MFAPP12/A-lignin3 were all lower than for pure PUF. MFAPP and alkali lignin exerted a noticeable influence on the physical and mechanical properties, leading to increases in density (35.4 kg/m3), thermal conductivity (32.68 mW/(m·K)), and compressive strength (160.5 kPa). Observations of the morphology and elemental composition of char residues after combustion indicated the formation of an intact, thick, and continuous char layer enriched with nitrogen and phosphorus elements, which acted as a protective shield for the underlying foam.

Cathodic protection shielding of coated buried pipeline

AbstractDuring the 2000s, the concept of cathodic protection (CP) shielding was first raised in open literature and remains debated between coatings professionals. The mechanism of CP shielding, and its understanding continue to be studied for different coatings with different approaches and using various techniques. From the CP shielding factors to the assessment methods, the published literature merits a deep analysis to capture the established knowledge and identify the research gaps to further tackle the issue for reliable coated buried structures. A holistic approach to this topic seems necessary where coatings ageing, cathodic protection, electrochemistry, and transport processes should be considered. In the first part of the present review, the recent works related to the understanding of CP shielding, coatings properties were considered before discussing the mechanisms involved underneath coatings. Transport phenomena and their relationship with cathodic protection performance in the presence of chemical and microbiological processes are discussed in the second part. Finally, CP shielding assessment methods and modeling works are presented and discussed from different perspectives.

Evaluating the Electromagnetic Shielding of Continuous Carbon Fiber Parts Produced by Additive Manufacturing.

Electronic devices are sensitive to electromagnetic (EM) emissions, and require electromagnetic shielding protection to ensure good operation, and prevent noise, malfunctioning, or even burning. To ensure protection, it is important to develop suitable material and design solutions for electronic enclosures. Most common enclosures are made with metal alloys using traditional manufacturing methods. However, using thermoplastic composites combined with additive manufacturing (AM) technologies emerges as an alternative that enables the fabrication of complex parts that are lightweight, consolidated, and oxidation- and corrosion-resistant. In this research, an AM technique based on material extrusion was used to print 2 mm-thick specimens with a multi-material made of micro-carbon fiber (CF)-filled polyamide that was reinforced at specific layers using continuous carbon fibers stacked with a 90° rotation to each other. The specimens' electromagnetic shielding effectiveness (EMSE) was evaluated in the frequency band of 0.03-3 GHz using the coaxial transmission line method. Depending on the number of CF layers, the EM shielding obtained can be up to 70 dB, with a specific shielding up to 60 dB.cm3/g, predominantly by the absorption mechanism, being 22 times higher than without the CF layers. These findings promote this innovative approach to lightweight customizable solutions for EM shielding applications.

Study on Shielding Effectiveness of High Transmittance Coating Film Glasses against Electromagnetic Pulse

This study investigated the shielding effectiveness (SE) of glass materials with conductive coatings by establishing a 3000 × 3000 × 3000 mm electromagnetic pulse (EMP)—shielded room according to the EMP shielding requirements in the US military standard MIL-STD-188-125-1. The EMP SE of conductive-coated glass samples was measured and verified with the broadband EMP conditions of 10 kHz∼1 GHz. The conductive thin film coating on the glass was made by mixing conductive materials, including In2O3, SnO2, Ta2O5, NbO, SiO2, TiO2, and Al2O3, at different ratios. The mixed solutions were then coated onto the glass targets to facilitate conductive continuity between the conductive oxides and the shielding metal structure. The glass samples had dimensions of 1000 × 600 mm, which had electrolytic conductivity σ = 4.0064 × 103∼4.7438 × 103 (S/cm), 74∼77% transmittance, and 6.4∼6.8 Ω/□ film resistance. The experimental results indicated that the glass had SE of 35∼40 dB under 1 GHz EMP, satisfying the US National Coordinating Center for Communications’ Level 3 shielding protection requirement of at least 30 dB. The glass attenuated energy density by more than 1000 times, which is equivalent to shielding over 97% of EMP energy. Accordingly, the glass materials can be used as high-transmittance conductive glass for windows of automobiles, vessels, and aircrafts to protect from EMPs.

Numerical simulation study on mesoscopic metallic foam core sandwich panels under hypervelocity impact

Due to its lightweight and superior energy absorption characteristics, metallic foams are exceptionally suitable for the protective shielding of spacecraft against debris. The mesoscopic structure of such a foam plays a pivotal role in enhancing its outstanding protective performance. Numerical simulations permit us to explore the damage mechanism of its internal structure and the evolving characteristics of debris clouds. By adopting the three-dimensional Voronoi tessellation in conjunction with the algorithm of background mesh mapping, this study constructed mesoscopic finite element models that accurately reflect the internal randomness and variability in ligament width within the metallic foam. Subsequently, numerical simulations were executed employing the FE-SPH adaptive method within the LS-DYNA. Comparative experimental cases substantiated the validity of the simulations, and an exhaustive mesh sensitivity analysis was conducted. Optimizing results from these simulations following a normal impact, we delved into the propagation of stress waves within the foam core, alongside the subsequent internal structural damage. Furthermore, we explored the damage mechanism of foam sandwich panels subjected to hypervelocity impacts. According to the fragmentation process of the projectile and the evolution of debris clouds, it was discerned that the random internal structure of the foam engenders an asymmetric and skewed debris cloud, dispersing its energy and culminating in multiple concentrated particle clusters with a predilection towards a particular direction. Tracking the velocity fluctuations of these ‘dominant particles’ and the inflicted damage on the rear facesheet revealed that the agglomerated tiny fragments of the projectile are primarily responsible for perforating the rear facesheet.