Natural Materials Research Articles

Unraveling the genetic basis of superior traits in Gossypium barbadense: From phenotype to genotype

G. barbadense is renowned for its high-quality fiber and is highly regarded as a natural material in the textile industry. However, research on cotton has mainly focused on G. hirsutum, and progress in sea island cotton has been relatively slow. There was limited understanding of the genetic loci and transcriptional regulatory mechanisms of important traits, and the genetic basis for the development of superior traits remains unclear. In this study, a recombinant inbred line (RIL) population was constructed using two sea island cotton parents from different cotton regions. The phenotypic characteristics of the two parents and the RIL population, as well as the phenotypic correlations, heritability, and genetic models of the RIL population, were comprehensively analyzed. The RIL population was genotyped using whole-genome resequencing technology, and a high-density intraspecific linkage map was constructed, consisting of 5295 bin markers and a total genetic map distance of 2721.79 centimorgans (cM). Phenotypic data collected from five different environments were used to detect 169 quantitative trait loci (QTLs) using the composite interval mapping method. Among these QTLs, 30 were related to agronomic traits, 61 were related to yield traits, and 78 were related to fiber quality traits. Additionally, 17 QTL clusters were detected, and the additive effects of these clusters explained the correlation between different phenotypic traits. Candidate genes for stable QTLs related to agronomic and yield traits were identified through variant annotation and functional prediction. Two bin markers associated with lint percentage (LP) were validated as potential breeding markers. Furthermore, using RNA-seq data of cotton fiber from the RIL population parents, the dynamic changes in gene expression during different developmental stages of cotton fiber were revealed, and important differentially expressed genes in the secondary cell wall development and metabolism network of fibers were identified. Importantly, through the combined analysis of fiber trait QTLs and transcriptomes, eight candidate genes involved in regulating fiber quality traits were predicted, and the genetic basis of the excellent allele site qFL_D04_1 in the breeding history of Chinese sea island cotton was elucidated. In summary, this study provides new genetic resources and potential breeding markers for cotton variety improvement, valuable theoretical information for understanding the genetic basis of important traits in sea island cotton, and effectively promotes the development of cotton biotechnology breeding.

Casimir interaction driven by hyperbolic polaritons

Abstract Casimir interaction is an intriguing phenomenon that is induced by electromagnetic quantum fluctuations, which dominates the interaction between microstructures at small separations and is essential for micro- and nano-electromechanical systems (MEMS and NEMS). However, Casimir interaction driven by hyperbolic polaritons remains an unexplored frontier. In this work, we investigate the Casimir interaction between natural hyperbolic material hexagonal boron nitride from the perspective of force distribution with different optical axis orientations for the first time. The attractive Casimir force is remarkably enhanced due to the excitation of volume-confined hyperbolic polaritons (HPs). Furthermore, distinct repulsive contributions to the force are observed due to surface-confined HPs that only exist when the optical axis is in-plane. The HPs are associated with a striking thickness dependence of spectral force properties, suggesting that the discrete volume-confined HPs lead to the attractive-repulsive transition of Casimir force. This work sheds light on the relation between HPs and the vacuum fluctuation-induced force, which could offer new opportunities for the development of the MEMS and NEMS.

Recent advances in prefabrication techniques for biobased materials towards a low-carbon future: From modules to sustainability

The evolution of building-structure manufacturing systems is propelled by dynamic shifts in formal requirements, prompting heightened research endeavors to enhance manufacturing process efficiency. Integrating renewable materials and technology is pivotal for sustainability, with natural material prefabrication offering promising solutions by reducing carbon footprint. This article comprehensively explores existing natural material prefabrication technologies, delving into their capabilities and assessing their suitability for application in single-family housing within Central and Eastern Europe. Additionally, this article deliberates a thorough assessment of bio-based materials in the construction sector towards a less carbon perspective, with a focus on advancements from 2015 to 2024. A bibliometric analysis of 949 research articles from Web of Science (WOS) and Scopus databases reveals a substantial increase in publications, rising from 29 in 2015 to 175 in 2023 and 17 in 2024 (and still counting), underscoring the growing emphasis on practical applications and technological progress in this field. The research findings offer valuable insights for practitioners, policymakers, and researchers, guiding the integration of renewable materials into traditional construction practices for a more sustainable built environment.

Recycled Eco-Concretes Containing Fine and/or Coarse Concrete Aggregates. Mechanical Performance

This study analysed the effect of substituting different percentages of natural aggregate with recycled aggregate from concrete crushing, using a coarse fraction as well as a fine fraction. Natural and recycled materials were classified in order to analyse the mechanical performance and impermeability of these eco-concretes in the fresh state as well as in the hardened state. A statistical analysis also determined whether the performance loss was significant from a statistical point of view, finding strength decreases of less than 13% in compressive strength and losses of less than 20% in flexural strength. An increasing trend was found in permeability as the percentage of recycled aggregate in the mix increased.

Evaluating the Effectiveness of Phellodendron Amurense Ruprecht Extract as a Natural Anti-Caries Material.

This study aimed to investigate the antibacterial and cytotoxic potential of Phellodendron amurense Ruprecht (PAR) extract against Streptococcus mutans (S. mutans) and explore the possibility of using PAR extract as an anticariogenic agent. Mixed extracts were prepared at 0, 1.25, 2.5, and 5 mg/mL concentrations, and an S. mutans-containing solution of 100 μL was inoculated into the medium. The survival rate of human keratinocyte (HaCaT) cells was assessed to confirm stability. One-way ANOVA was performed to evaluate the antibacterial activity against S. mutans and the proliferation of HaCaT cells. Higher concentrations of the PAR extract showed more growth inhibition of S. mutans over time, with the complete inactivation of S. mutans at 5 mg/mL. HaCaT cell density was reduced at a PAR extract concentration of 1.25 mg/mL, but IC50 was not observed, confirming that the concentration used did not affect the cytotoxicity and proliferation. Results showed that the PAR extract was excellent as a natural substance with anticariogenic effects that inhibited the growth of S. mutans and did not affect the cell viability, thus indicating the potential for clinical application.

Health Risk Assessment of Heavy Metals in Soils of a City in Guangdong Province Based on Source Oriented and Monte Carlo Models

Taking a city in Guangdong Province as the research area, the concentration and spatial distribution characteristics of heavy metals in the surface soil were studied to clarify the situation of soil heavy metal pollution and priority control factors, providing basic data for the prevention and control of soil heavy metal pollution in the city. The content characteristics of heavy metals in 221 soil samples in the city were analyzed, and the potential health risk assessment and source analysis were carried out through the Monte Carlo model, the potential health risk assessment (HRA) model, and the PMF receptor model. It was found that heavy metals ω(As), ω(Hg), ω(Cd), ω(Pb), ω(Cr), ω(Cu), ω(Ni), and ω(Zn) in the soil of the city were 18.16, 0.43, 1.46, 68.57, 98.34, 64.19, 26.53, and 257.32 mg·kg-1, respectively, with a moderate to high degree of variation. Except for Ni concentration, the soil concentrations of other heavy metal elements exceeded the background values of soil in Guangdong Province to a certain extent, and the concentrations of Cd and Zn exceeded the national secondary standards, resulting in severe heavy metal pollution; the main sources of heavy metals were industrial sources, and natural parent materials, lead battery manufacturing, transportation, artificial cultivation, and pesticide and fertilizer inputs also had an undeniable impact on the accumulation of heavy metals in the soil. Heavy metals in the soil had a certain degree of tolerable carcinogenic health risk for both children and adults, whereas non-carcinogenic risks could be ignored. The potential health risk of children was greater than that of adults, and the main exposure route was through oral intake. The input sources of pesticides and fertilizers and As should be the main controlling factors for the health risks of heavy metals in the city's soil, followed by mixed sources and Cr. There were differences in the spatial distribution characteristics and relative pollution levels of heavy metals, and it is necessary to deepen zoning monitoring and control, strengthen soil pollution prevention and control, and reduce human input of heavy metals in soil.

Molecular‐Engineered Wool for Sustainable All‐Weather Radiative Cooling Textiles

AbstractPersonal thermal regulation through passive radiative cooling is an effective strategy to achieve sustainable development. Although recent advances have introduced various cooling textile designs, the extensive use of materials unsuitable for common textiles, alongside coating or compositing technologies, not only compromises the wearability and safety of these textiles but also impacts green sustainability. Herein, it is shown that wool is a promising natural material for transferring mid‐infrared human body radiation, but the high absorption in the solar spectrum prohibits wool from achieving satisfactory daytime radiative cooling. Thus the natural wool impregnates zinc ions into the protein chains to form a zinc‐ion woolen (wool‐Zn) fabric. The wool‐Zn fabric can provide humans with a cooling sensation both indoors and daytime outdoors, showing a temperature reduction of 2 °C on human skin indoors and a reduction of 7 °C on artificial skin under direct sunlight, respectively, when covered by wool‐Zn fabrics compared to when covered with cotton. Moreover, the wool‐Zn fabric shows desirable antibacterial properties and durability against washing and abrasion, while maintaining desirable wearability. As a result, the wool‐Zn fabric shows great potential for commercial application in personal thermoregulation and provides an effective avenue toward sustainable energy and environment.

Diatomite-incorporated hierarchical scaffolds for osteochondral regeneration

Osteochondral regeneration involves the highly challenging and complex reconstruction of cartilage and subchondral bone. Silicon (Si) ions play a crucial role in bone development. Current research on Si ions mainly focuses on bone repair, by using silicate bioceramics with complex ion compositions. However, it is unclear whether the Si ions have important effect on cartilage regeneration. Developing a scaffold that solely releases Si ions to simultaneously promote subchondral bone repair and stimulate cartilage regeneration is critically important. Diatomite (DE) is a natural diatomaceous sediment that can stably release Si ions, known for its abundant availability, low cost, and environmental friendliness. Herein, a hierarchical osteochondral repair scaffold is uniquely designed by incorporating gradient DE into GelMA hydrogel. The adding DE microparticles provides a specific Si source for controlled Si ions release, which not only promotes osteogenic differentiation of rBMSCs (rabbit bone marrow mesenchymal stem cells) but also enhances proliferation and maturation of chondrocytes. Moreover, DE-incorporated hierarchical scaffolds significantly promoted the regeneration of cartilage and subchondral bone. The study suggests the significant role of Si ions in promoting cartilage regeneration and solidifies their foundational role in enhancing bone repair. Furthermore, it offers an economic and eco-friendly strategy for developing high value-added osteochondral regenerative bioscaffolds from low-value ocean natural materials.

Determination Of Drag And Inertia Coefficients By An Analytical Model

Hard structures like dykes or groins have been recognized for their negative environmental impact and limited durability in the face of climate change (Sutton-Grier et al., 2015). The concept of Shore Soft Engineering (SSE) has allowed ecological considerations to be embedded in the design of coastal protection (Hartig et al., 2011). Among emerging defense structures, nature-based solutions are built with natural materials and rely on physical properties and mechanisms observed in nature. They aim to protect, manage and restore ecosystems while providing some benefit to the human-being and biodiversity (Cohen-Shacham et al., 2016); they offer an interesting alternative to hard structures. However, implementing these solutions in urbanized coastal areas where ecosystems are vulnerable can be challenging. Another alternative approach is using biomimetic solutions, which can provide the functions of natural systems like seagrass, dunes, or coral through robust human-made constructions. Natural habitats exist in a variety of more or less complex forms, ranging from rigid (mangroves, coral) to flexible (seagrass) (Mullarney and Henderson, 2018); and they drive changes in the current profile, in wave dissipation or in sediment motion. Understanding how to mimic these systems, in particular their internal geometry and hydrodynamic effects, is challenging. This complexity makes the development of biomimetic solutions difficult (Perricone et al., 2023). In this context, this study strictly focuses on wave dissipation by flexible systems. Wave dissipation by natural habitats has been extensively studied through laboratory experiments (Houser et al., 2015) and in-situ measurements (Bradley and Houser, 2009). The pioneer analytical model (Dalrymple et al., 1984) depicted aquatic vegetation as rigid cylinders; however, the rigidity assumption fails to capture the inherent flexibility of plants. Alternative strategies emerged to account for this flexibility, such as using an empirical drag coefficient (Mendez and Losada, 2004) or introducing an effective length, representing the length that a rigid cylinder would have to dissipate the same wave height as flexible cylinders (Luhar and Nepf, 2016). However, to define this effective length or an empirical drag coefficient, it is necessary to carry out in-situ measurements. Numerous analytical models based on force balance (Luhar and Nepf, 2016; Leclercq and de Langre, 2018) have been developed to represent the movement of flexible vegetation like seagrass. These models depict the flexible vegetation as a series of segmented rigid stems attached to each other and subjected to oscillating flows. Some models attempt to link stem motion with wave dissipation to integrate this coupling into numerical models (Yin et al., 2022). However, these models still require unknown quantities such as drag and inertial coefficients. The present study aims to develop an analytical model for determining drag and inertial coefficients based solely on the geometry, the structure flexibility and wave forcing. At last, the method could help better represent the dissipation into numerical simulations without the need for prior parametrization.

Natural ceramic clay and cucurbituril guest-host reconfiguration for smart light, humidity, solvent and temperature responsiveness

Aiming to endow natural minerals with fast, high-sensitivity, and controllable smart light, humidity, solvent and temperature responsiveness, a novel ceramic clay and cucurbituril (CB) guest-host system (MVCB) inspired by nature was self-assembled and rearranged via an ingenious and simple design successfully. For the first time, the multi-functional MVCB not only displayed a high intelligent multi-stimuli responsiveness as light, humidity, solvent, and temperature switches, but also had multiple selective molecular recognition responses because of different organic vapor with CB and asymmetrical bilayer clay. For instance, due to the factors of guest-host and slow release, the average response speed of self-assembled shuffling the MVCB in methanol was as high as 108°/s compared with bilayer film without CB (20°/s). Besides, the MVCB exhibited controllable swift movement and was bending for grabbing three times its own weight. Moreover, the ultra-wide operating temperature of the MVCB from was ranging −196 to 300 °C under extreme condition. More interestingly, the MVCB presented a unique and compliable self-driven, smart switch, shape memory, environmental awareness and soft robotic gripper owing to the asymmetrical swelling and supramolecular of the CB. This work not only brings a simple, cost-effective, large-scale, and efficient strategy for multi-functionalized natural minerals materials, but also opens potential applications for intelligent response, extremely resistant substances, energy conversion and soft robotics.

Fabrication of chitosan-based fluorescent hydrogel membranes cross-linked with bisbenzaldehyde for efficient selective detection and adsorption of Fe2+

Chitosan, as a natural biomass material, is green, recyclable, sustainable and well biocompatible. The molecular chain is rich in active groups such as amino and hydroxyl groups, and its preparation of fluorescent probes has the advantages of biocompatibility and efficient detection performance. In this study, a bis(benzaldehyde) (BHD) fluorescent functional molecule was designed. Then a series of fluorescent chitosan-based hydrogel films (CSBHD) were prepared using chitosan as raw material and BHD as cross-linking agent. As a fluorescent probe for metal ions, CSBHD was able to efficiently detect Fe2+ with a linear correlation of fluorescence intensity in the range of 0–160 μM, and the limit of detection (LOD) was 0.55 μM. Moreover, it has excellent adsorption performance for Fe2+ ions, with a maximum adsorption capacity of 223.5 g/mg at 500 mg/L Fe2+ concentration. Finally, we characterised the structure and microscopic morphology of CSBHD films and found that CSBHD as a hydrogel film has a high cross-linking density, good water resistance, excellent thermal stability, strong resistance to swelling, and excellent stability in cycling tests. Hence, it has great potential for application in adsorption and detection of Fe2+ ions. It also provides a good strategy for the application of chitosan based fluorescent probe materials in environmental monitoring and heavy metal ion adsorption.

Composite Materials Based on Waste Chicken Feather Fibers for Oil-Spill Management

ABSTRACT Oil spills remain one of the greatest man-made ecological threats, despite numerous advanced cleanup approaches. They still pose a major challenge in the search for materials and technologies that work as efficiently and sustainably as possible. Promising natural materials include poultry feathers, which are produced in large quantities every day as a byproduct of the meat industry. In this study, the influence of different forms of absorbents (loose feathers, pillows, and sheets) based on chicken feathers and the addition of an inorganic absorbent, sepiolite, on their absorption capacity was investigated. The chemical and physical surface properties, like morphology, chemical composition, zeta potential, surface free energies and oil absorption capacities were analyzed. The Gibbs free energy of immersion wetting with oil and the work of adhesion of the adsorbents, calculated based on contact angle measurements, were confirmed by the tests of adsorption capacities according to the ASTM 726–12 standard. The results showed that pure loose feathers have the highest oil adsorption capacity, while feather pillows have only half, and composite sheets have only a quarter of this capacity. The addition of inorganic adsorbent sepiolite did not increase the absorption capacity of the composites.

Lignin-Derived Lightweight Carbon Aerogels for Tunable Epsilon-Negative Response.

Electromagnetic (EM) metamaterials have garnered considerable attention due to their capacity to achieve negative parameters, significantly influencing the integration of natural materials with artificially structural media. The emergence of carbon aerogels (CAs) offers an opportunity to create lightweight EM metamaterials, notable for their promising EM shielding or absorption effects. This paper introduces an efficient, low-cost method for fabricating CAs without requiring stringent drying conditions. By finely tuning the ZnCl2/lignin ratio, the porosity is controlled in CAs. This control leads to an epsilon-negative response in the radio-frequency region, driven by the intrinsic plasmonic state of the 3D carbon network, as opposed to traditional periodic building blocks. This approach yields a tunable and weakly epsilon-negative response, reaching an order of magnitude of -103 under MHz frequencies. Equivalent circuit analysis highlights the inductive characteristics of CAs, correlating their significant dielectric loss at low frequencies. Additionally, EM simulations are performed to evaluate the distribution of the electric field vector in epsilon-negative CAs, showcasing their potential for effective EM shielding. The lignin-derived, lightweight CAs with their tunable epsilon-negative response hold promise for pioneering new directions in EM metamaterials and broadening their application in diverse extreme conditions.

Ecofriendly and high-performance flexible pressure sensor derived from natural plant materials for intelligent audible and silent speech recognition

Flexible pressure sensors (FPSs) are widely used in human–computer interaction (HCI) and medical diagnoses, but their further development faces several challenges. Integrating artificial intelligence (AI) with FPSs is indispensable for advancing the cognitive capabilities of HCI systems, but the FPS must also be ecofriendly, cost-effective, and high-performance to meet the demands of environmental protection and sustainable development. Here, a biodegradable capacitive FPS is presented that is fabricated from natural plant materials (i.e., cornstarch and lignocellulose) while exhibiting remarkable attributes such as high sensitivity (2.427 kPa−1 at 0–2 kPa), rapid response/recovery time (20/24 ms), extremely low detection limit (∼10 Pa), outstanding stability (> 6000 fatigue tests), excellent biocompatibility (survival rate exceeding 99 % in cell viability assays), and prominent biodegradability (complete degradation within 24 h). Prepared sensors were integrated with optimized AI algorithms, embedded systems, and wireless transmission technologies to develop a dual-functional (i.e., audible and silent) speech recognition system that achieved recognition rates exceeding 95 %. The developed sensor is expected to play a crucial role in future HCI and medical assistance applications.

Enamel remineralisation prospect of Moringa Oleifera hydrogel, eggshell hydrogel versus sodium fluoride varnish on artificially demineralised primary teeth: in vitro study.

The purpose of the present in vitro study is to investigate and compare the remineralising potential of Moringa Oleifera extract, eggshell, and sodium fluoride varnish on microhardness of artificially demineralised enamel of primary teeth with biomimetic minimally invasive approach following the world paradigm shift towards natural products in paediatric dentistry. Sample size included 44 primary molars. The mineral content and surface microhardness of all specimens were initially assessed using energy dispersive x-ray examination (EDX) and Vickers microhardness. The specimens were artificially demineralised for 96 h at a temperature of 37°C and then reassessed directly after demineralisation. The demineralised enamel specimens were randomly divided into four groups according to the remineralisation regimen utilised. Group 1: Artificial saliva (control); Group 2: Sodium fluoride varnish; Group 3: Eggshell hydrogel; and Group 4: Moringa Oleifera hydrogel. The specimens were stored for 8 days and then subsequently evaluated using EDX and microhardness assessment by Vickers microhardness test and scanning electron microscope (SEM). Results: Regarding the microhardness test, there was a significant difference between the Moringa Oleifera group and Eggshell group compared to fluoride varnish (p < 0.05). Regarding EDX analysis, there was a statistically significant difference (p < 0.05) between Moringa Oleifera group and Eggshell group compared to fluoride varnish as the highest values were for Moringa Oleifera and Eggshell. On the other hand, there was no statistically significant difference (p > 0.05) between Moringa Oleifera and Eggshell in both the measurements. Moringa Oleifera and Eggshell might be considered as a biomimetic natural material capable of guiding enamel tissue remineralisation in early carious lesion of primary teeth. This research demonstrated the capability for early enamel caries to be remineralised using novel materials with a naturally counterpart implicated in biomineralisation as proved to be more effective than traditionally used fluoride varnish in primary teeth.

Effects of soil conditioners on vineyard saline soil physicochemical properties and bacterial community in arid areas

AbstractSoil salinization adversely affects soil quality and ecosystem. Many researches have tried to ameliorate saline soils by soil conditioners. However, little is known about the differences in the responses of soil bacterial communities to natural and artificial conditioners applied to saline soils. Therefore, in this study, the effects of natural humic acid (IK), synthetic polymer (IP), and composite material (IF) (mixture of IK and IP (1:1)) on bacterial community structure and functional genes in saline soil were evaluated to clarify their differences. The results showed that the application of the three soil conditioners significantly reduced soil pH and Na+ content but increased soil alkaline phosphatase, urease, invertase and catalase activities, bacterial diversity, and nutrients, compared to the control (no conditioner). IK application increased bacterial relative abundance (e.g., Subgroup_6, RB41, MND1, and KD4‐96) and metabolic functions (e.g., Two‐component system and Biosynthesis of amino acids) by increasing soil nitrogen and maintaining K+ and Na+ balance. IP application increased soil alkaline phosphatase and urease activities as well as bacterial relative abundance (e.g., Subgroup_6, RB41, MND1, Gemmatimonadaceae, and KD4‐96) and metabolic functions (e.g., Quorum sensing and carbon metabolism) by increasing soil organic carbon/nitrogen content. IF application increased the bacterial relative abundance of Subgroup_6, RB41, and MND1 by increasing soil available nitrogen and regulated their metabolic pathways (e.g., ABC transporters and microbial metabolism). On the whole, IK, IP, and IF could regulate the structure and function of soil bacterial community in saline soils. This study clarifies difference in the effects of different soil conditioners on the amelioration of saline soils from the perspective of soil microbiology, and provides a reference for the amelioration of saline soils in arid areas.

Laser-induced graphene formation on different wood species: Dependence of electronic performance on intrinsic features of certain types of wood

Conductive, 3D, porous graphene can be produced with a CO2 laser from a large variety of materials, including wood, at room temperature, and under inert atmosphere or after treatment for fire protection. Here, we investigated the suitability for direct conversion of 46 typical European and Asian woods into laser-induced graphene (LIG), without pre-treatment. The LIG was characterized by resistance measurements to determine if a conductive layer had formed, and via Raman spectroscopy. Here, we show, for the first time, that it is possible to produce LIG on certain woods under atmospheric conditions without additional fire protection treatment. We determined that the ability to produce LIG on untreated, natural wood under ambient atmosphere is favoured overall by a high density and a diffuse-porous xylem structure, as well as a high soluble lignin content. Some of these characteristics are similar to those required for high yields in char production. Problematic for the production of LIG-based electronics is the presence of pronounced growth rings, or other geometric wood features, with density variations, which can be reduced using specific cuts with minimized growth rings and absence of rays. This is the first time that untreated wood has been directly converted into LIG using a conventional CO2 laser and ambient atmosphere. Our results represent a further step towards the development of a new generation of sustainable electronics relying on natural materials.

An investigation of timber frame housing in Vietnamese Mekong River Delta

Timber frame housing is one of the most common structures in many countries in the world. In Vietnam, timber frame buildings are well-known for having special whittling techniques that should be considered a lesson for modern methods. In the Vietnamese Mekong River Delta, the housing in rural areas was built mostly with timber frames, and some housing was built with bamboo frames and used natural materials such as nipa-leave, and coconut-leave. Therefore, the study aims to investigate the characteristics of timber frame housing in the Mekong River Delta. To achieve this, firstly, an on-site investigation of ten local housings in the Vietnamese Mekong River Delta is carried out. Secondly, the architectural characteristics of local housing are introduced, and finally, we analyze the details of timber frames. The result shows that the timber frame housing in the Vietnamese Mekong River Delta has the following features: simple structure, light framing, and a flexible connection to other local materials. These characteristics should be considered in detail as a lesson for housing design in the region.

Controlling the broadband enhanced light chirality with L-shaped dielectric metamaterials

The inherently weak chiroptical responses of natural materials limit their usage for controlling and enhancing chiral light-matter interactions. Recently, several nanostructures with subwavelength scale dimensions were demonstrated, mainly due to the advent of nanofabrication technologies, as a potential alternative to efficiently enhance chirality. However, the intrinsic lossy nature of metals and the inherent narrowband response of dielectric planar thin films or metasurface structures pose severe limitations toward the practical realization of broadband and tailorable chiral systems. Here, we tackle these problems by designing all-dielectric silicon-based L-shaped optical metamaterials based on tilted nanopillars that exhibit broadband and enhanced chiroptical response in transmission operation. We use an emerging bottom-up fabrication approach, named glancing angle deposition, to assemble these dielectric metamaterials on a wafer scale. The reported strong chirality and optical anisotropic properties are controllable in terms of both amplitude and operating frequency by simply varying the shape and dimensions of the nanopillars. The presented nanostructures can be used in a plethora of emerging nanophotonic applications, such as chiral sensors, polarization filters, and spin-locked nanowaveguides.

Natural mineral raw materials as granular filtering materials in industrial and waste water treatment

Analysis of currently existing methods of natural and waste water treatment from heavy metals has shown that one of the most promising is the sorption method using natural inorganic materials as sorbents: zeolite, diatomite, and vermiculite. The relevance of the topic is dictated by the need to develop an original technology of wastewater treatment and water treatment, which allows constant monitoring of the level of pollution of natural waters by industrial wastewater from metallurgical enterprises. The proposed methods of sorbent modification create a basis for studying the structure, porosity, and sorption capabilities of the mentioned natural materials. All three minerals: zeolite, diatomite, and vermiculite belong to highly porous, structured materials, promising for use as stable sorption systems in water treatment and water purification. The influence of physical and chemical characteristics of natural sorbents and the application of new promising environmentally safe materials and reagents for water treatment are considered. The sorption of copper ions on natural zeolite material before and after its modification by hydrothermal method was investigated. The activity of sorbents was estimated by the value of sorption capacity, i.e. the amount of heavy metal ions absorbed by a unit mass of sorbent based on zeolite and its modified form.