Conventional Materials Research Articles

Evaluation of living bacterial therapy assisted by pH/reactive oxygen species dual-responsive sodium alginate-based hydrogel for wound infections

The enhancement of antimicrobial wound dressings is of utmost importance in light of the escalating risk of antibiotic resistance caused by excessive antibiotic usage. Conventional antimicrobial materials eradicate pathogenic bacteria while impeding the proliferation of beneficial bacteria during the management of wound infections, thereby disturbing the equilibrium of the skin micro-ecosystem and engendering recurrent cutaneous complications. Lactobacillus rhamnosus (L.rha) is a probiotic that can inhibit the growth of certain pathogenic bacteria by secreting a large number of metabolites. In this paper, we synthesized a cross-linker (SPBA) with a boric acid molecule from succinic acid and 4-(bromomethyl)phenylboronic acid, which formed a boric acid ester bond with a diol on the natural polysaccharide sodium alginate (SA), and obtained a pH/reactive oxygen species (ROS) dual-responsive hydrogel (SA-SPBA) for loading L.rha to treat wound infections. The SA-SPBA@L.rha hydrogel improves the survival of L.rha during storage and has good injectability as well as self-healing properties. The hydrogel showed good biocompatibility, the antimicrobial effect increases in a dose-dependent manner, and it has a certain antioxidant and anti-inflammatory capacity, accelerating wound repair. The use of SA-SPBA@L.rha hydrogel provides a safe and effective strategy for the repair of skin wound infections.

Micromechanics stiffness upscaling of plant fiber-reinforced composites

Fiber-reinforced green composites made from natural plant fibers are an increasingly popular sustainable alternative to conventional high-performance composite materials. Given the variety of natural fibers themselves, and the even larger variety of possible composites with specific fiber dosage, fiber orientation distribution, fiber length distribution, and fiber–matrix bond characteristics, micromechanics-based modeling is essential for characterizing the macroscopic response of these composites. Herein, an analytical multiscale micromechanics model for elastic homogenization is developed, capable of capturing the variety. The model features (i) a nanoscopic representation of the natural fibers to predict the fiber stiffness from the universal stiffness of the fiber constituents, mainly cellulose, (ii) a spring-interface model to quantify the compliance of the fiber–matrix bond, and (iii) the ability to model any (and any combination of) orientation distribution and aspect ratio distribution. Validation is performed by comparing the predicted stiffness to experimental results for as many as 73 composites available in the literature. Extensive sensitivity analyses quantify the composite stiffening upon increasing fiber volume fraction, fiber alignment, fiber length, and fiber–matrix interface stiffness, respectively.

Solar-heated mono-domain-structured ferrimagnetic cellulosic sponge fabricated by using bidirectional freeze casting for energy-efficient liquid adsorption

Liquid adsorption has a wide range of industrial and environmental applications. In recent years, interest in liquid adsorption technology that leverages porous materials has surged, primarily driven by these materials’ substantial surface area and adjustable wettability. However, high tortuous structures of conventional porous materials impede the flow of liquids, limiting their applicability in situations requiring rapid liquid adsorption such as oil spill cleanups. This study proposed two strategies for rapid liquid adsorption. We introduced a polydimethylsiloxane (PDMS) wedge to control ice crystal growth by generating a dual temperature gradient. This led to a mono-domain lamellar structure composed of vertically aligned channels. Cubic iron oxide nanoparticles (CION) were also utilized to enhance solar heating, that enabled rapid adsorption, even of high-viscosity liquids, without an external power supply unit for heating sorbents. The application of a solar-heated ferrimagnetic cellulosic sponge with precisely controlled channels facilitates the rapid removal of high-viscosity oils, which have traditionally been challenging for large-scale oil spill cleanups in oceans.

Clinical Outcomes of Polyetheretherketone (PEEK) Hybrid Prosthesis in All-on-Four Rehabilitation: A Systematic Review Protocol

Background The “all-on-four” concept represents a significant advancement in dental implantology. particularly beneficial in cases of extensive jaw bone loss where invasive bone regeneration procedures are typically required. However, the successful implementation of this technique necessitates meticulous planning concerning implant selection, materials, and prosthesis design. The recent introduction of PEEK (Polyetheretherketone) in dentistry, especially in all-on-four prosthetics, prompts questions regarding its clinical efficacy and comparative biomechanical and biological advantages over conventional materials such as titanium and zirconia. While some studies have compared PEEK with other materials, systematic reviews evaluating its efficacy are scarce. This systematic review protocol intends to assess the evidence regarding the viability of PEEK as a potential alternative within the all-on-four approach in dental implantology. Methods This systematic review protocol will adhere to the Cochrane Handbook for Systematic Review of Interventions and align with the Methodological Expectations of the Cochrane Intervention Reviews (MECIR) guidelines. Utilizing a comprehensive search strategy, multiple databases, including PubMed, EMBASE, Scopus, EBSCO, Web of Science, Cochrane Central, and registries of clinical trials, will be explored. The search aims to identify randomized controlled trials and non-randomized studies investigating the application of PEEK in the all-on-four approach for dental procedures. Emphasizing clinically relevant outcomes such as implant survival, prosthesis success, peri-implant complications, and patient satisfaction, this review aims to provide insights into the effectiveness and potential benefits of using PEEK in all-on-four prosthetics. Non-randomized studies will be assessed for bias using ROBINS-I, while randomized controlled trials will undergo evaluation with the Cochrane Risk of Bias assessment tool, ROB II. Discussion The outcomes derived from this systematic review hold great significance for dental practitioners exploring the all-on-four concept. Understanding PEEK’s advantages and limitations compared to titanium and zirconia facilitates tailored treatment plans, enhancing success and satisfaction, ultimately improving dental care quality. Systematic review registration PROSPERO: CRD42024531175 (Registered on 13/04/2024).

Effect of Drying Conditions and Jojoba Oil Incorporation on the Selected Physical Properties of Hydrogel Whey Protein-Based Edible Films.

Edible hydrogel coatings or films in comparison to conventional food packaging materials are characterized as thin layers obtained from biopolymers that can be applied or enveloped onto the surface of food products. The use of lipid-containing hydrogel packaging materials, primarily as edible protective coatings for food applications, is recognized for their excellent barrier capacity against water vapor during storage. With the high brittleness of waxes and the oxidation of different fats or oils, highly stable agents are desirable. Jojoba oil obtained from the jojoba shrub is an ester of long-chain fatty acids and monovalent, long-chain alcohols, which contains natural oxidants α, β, and δ tocopherols; therefore, it is resistant to oxidation and shows high thermal stability. The production of hydrogel films and coatings involves solvent evaporation, which may occur in ambient or controlled drying conditions. The study aimed to determine the effect of drying conditions (temperature from 20 to 70 °C and relative humidity from 30 to 70%) and jojoba oil addition at the concentrations of 0, 0.5, 1.0, 1.5, and 2.0% on the selected physical properties of hydrogel edible films based on whey protein isolate. Homogenization resulted in stable, film-forming emulsions with bimodal lipid droplet distribution and a particle size close to 3 and 45 µm. When higher drying temperatures were used, the drying time was much shorter (minimum 2 h for temperature of 70 °C and relative humidity of 30%) and a more compact structure, lower water content (12.00-13.68%), and better mechanical resistance (3.48-3.93 MPa) of hydrogel whey protein films were observed. The optimal conditions for drying hydrogel whey protein films are a temperature of 50 °C and an air humidity of 30% over 3 h. Increasing the content of jojoba oil caused noticeable color changes (total color difference increased from 2.00 to 2.43 at 20 °C and from 2.58 to 3.04 at 70 °C), improved mechanical elasticity (the highest at 60 °C from 48.4 to 101.1%), and reduced water vapor permeability (the highest at 70 °C from 9.00·10-10 to 6.35·10-10 g/m·s·Pa) of the analyzed films. The observations of scanning electron micrographs showed the heterogeneity of the film surface and irregular distribution of lipid droplets in the film matrix.

Toward high selectivity of sensor arrays: Enhanced adsorption interaction and selectivity of gas detection (N2, O2, NO, CO, CO2, NO2, SO2, AlH3, NH3, and PH3) on transition metal dichalcogenides (MoS2, MoSe2, and MoTe2)

Resistive gas sensors are essential for monitoring air quality, ensuring industrial safety, and controlling automotive emissions. However, conventional materials used for sensing layers often suffer from poor selectivity and require elevated operating temperatures, limiting their effectiveness. This study introduces a novel approach to address these challenges by utilizing the intrinsic physicochemical properties of Mo-bearing transition-metal dichalcogenides (TMDs). The findings reveal that variable charge availability on TMD surfaces leads to highly selective adsorption enhancements, resulting in significant differences in the TMD responses to various molecules, even at room temperature. This results in an exceptional relative sensitivity of the TMD monolayers, which in the case of combustion products exceeds what is feasible under the same conditions by conventional sensing materials such as ZnO and TiO2 by three orders of magnitude. Such an unprecedented variation in responses results in distinct sensing profiles. This enables effective cross-referencing of responses, offering significant benefits for sensor arrays. Consequently, even in relatively simple setups, TMD-based devices have the potential to prevent false-positive signals and even enable the determination of the composition of gas mixtures, which, if utilized, could revolutionize the field of gas monitoring with innovative lab-on-a-chip solutions.

Reducing Voltage Hysteresis in Li-Rich Sulfide Cathodes by Incorporation of Mn.

Conventional intercalation-based cathode materials in Li-ion batteries are based on charge compensation of the redox-active cation and can only intercalate one mole of electron per formula unit. Anion redox, which employs the anion sublattice to compensate charge, is a promising way to achieve multielectron cathode materials. Most anion redox materials still face the problems of slow kinetics and large voltage hysteresis. One potential solution to reduce voltage hysteresis is to increase the covalency of the metal-ligand bonds. By substituting Mn into the electrochemically inert Li1.33Ti0.67S2 (Li2TiS3), anion redox can be activated in the Li1.33-2y/3Ti0.67-y/3Mn y S2 (y = 0-0.5) series. Not only do we observe substantial anion redox, but the voltage hysteresis is significantly reduced, and the rate capability is dramatically enhanced. The y = 0.3 phase exhibits excellent rate and cycling performance, maintaining 90% of the C/10 capacity at 1C, which indicates fast kinetics for anion redox. X-ray absorption spectroscopy (XAS) shows that both the cation and anion redox processes contribute to the charge compensation. We attribute the drop in hysteresis and increase in rate performance to the increased covalency between the metal and the anion. Electrochemical signatures suggest the anion redox mechanism resembles holes on the anion, but the S K-edge XAS data confirm persulfide formation. The mechanism of anion redox shows that forming persulfides can be a low hysteresis, high rate capability mechanism enabled by the appropriate metal-ligand covalency. This work provides insights into how to design cathode materials with anion redox to achieve fast kinetics and low voltage hysteresis.

Strain hardening behavior in T-carbon: A molecular dynamics study

T-carbon, a new carbon allotrope essentially composed of intra-tetrahedron bonds and inter-tetrahedron bonds, has attracted strong scientific interest in recent years due to its excellent mechanical performance for a wide range of applications. This study demonstrates that strain hardening can endow T-carbon with exceptional mechanical strength at a high compressive strain under plastic deformation, which is rarely observed in conventional carbon-based materials. Molecular dynamics simulations reveal that this behavior occurs in T-carbon nanowires and is caused by graphitization, where their original sp3-dominated carbon network transforms into a stronger sp2-network. Further analysis shows that graphitization occurs due to the breaking of intra-tetrahedron bonds, which is dominated by the deformation behavior of inter-tetrahedron bond angles. Particularly, when the deformation angle is small, only a small portion of the strain energy is stored in the tetrahedrons, while the remaining energy is released by breaking the intra-tetrahedron bonds of T-carbon nanowires, thus leading to graphitization. Moreover, such underlying mechanisms behind strain hardening and graphitization are found to occur in bulk T-carbon. This strain hardening potentially enables T-carbon to overcome the strength–ductility tradeoff issue of high strength leading to ductility loss.

Environment friendly sustainable concrete produced from marble waste powder

<p>Concrete is an indispensable construction material renowned for its versatility and durability, yet its traditional components pose significant environmental challenges. The cement industry is a major emitter of CO2, while the extensive extraction of natural aggregates depletes finite resources. In response, researchers have explored alternative materials like Marble Waste Powder (MWP) as sustainable substitutes in concrete production. This study investigates the feasibility of incorporating MWP as partial replacements for cement and fine aggregate, examining substitution fractions of 25% and 35%. Through experimental analysis, the mechanical properties and cost implications of these modified concrete blends are evaluated. The research findings reveal that integrating MWP into concrete formulations enables the production of high-strength concrete at a reduced cost, offering a promising solution to enhance the sustainability of construction practices. By partially replacing conventional materials with MWP, the environmental impact associated with concrete production can be mitigated, contributing to efforts aimed at reducing carbon emissions and conserving natural resources. Additionally, the study underscores the importance of eco-friendly innovations in construction materials, emphasizing the need for sustainable alternatives to meet the growing demand for infrastructure development while minimizing environmental harm. Overall, this research highlights the novel use of MWP as a sustainable alternative in concrete production, showcasing its potential to address environmental concerns and promote more eco-conscious construction practices. Through the exploration of mechanical performance and economic feasibility, the study provides valuable insights for advancing sustainability in the construction industry and achieving long-term environmental stewardship.</p>

Enhanced supercapacitor performance through synergistic electrode design: Reduced graphene oxide-polythiophene (rGO-PTs) nanocomposite

In this investigation, we introduce an innovative method for the fabrication of a 2D/2D nanocomposite, involving the in-situ functionalization of graphene oxide (GO) with thiophene monomer. This approach employs a modified surfactant-based bi-solvent swollen liquid crystalline lamellar mesophase (SLCLM) nanoreactor system, utilizing dimethyl sulfoxide and water as primary solvents. The nanocomposite is formed via simultaneous reactions at both the edge and basal plane of GO with thiophene monomers, resulting in polymerization and reduction to generate graphene oxide-polythiophene (rGO-PTs) nanocomposite.We assess the pseudocapacitive properties of rGO-PTs in a 2 M HCl electrolyte. The cyclic voltammetry (CV) investigations reveal distinctive redox curves, indicative of the materials capacitive behaviour. In the galvanostatic charge–discharge (GCD) study, the rGO-PTs exhibits a discharge duration of 169.50 s within a potential window of −0.2 to 1 V at a current density of 7.5 A/g. This performance corresponds to a significantly higher specific capacitance of 1412 F/g, sustained over 10000 cycles as asymmetric capacitor. Notably, the rGO-PTs nanocomposite retains 106 % of its initial capacitance even after a number cycles, tested at a scan rate of 50 mV/s. The exceptional durability and electrochemical performance of the rGO-PTs nanocomposite position it as a promising alternative to conventional materials such as metals, metal oxides, pure carbonaceous substances, and polymers. The simplicity of the synthesis process, coupled with the nanocomposites outstanding electrochemical characteristics, underscores rGO-PTs potential for advancing in the field of energy storage and supercapacitor technology.

Nonwoven acoustic panels from Himalayan nettle (Girardinia diversifolia L.) fibre

Sound absorption panels are being used extensively to mitigate the problem of noise pollution in buildings. Conventional materials used for sound absorption include glass wool, rock wool, mineral wool, asbestos, melamine, and polyurethane foam. However, recent studies show these materials can cause respiratory and skin problems. This has led to the search for natural and ecofriendly alternatives for sound absorbing materials. Lignocellulosic materials are cheap, renewable, biodegradable, and abundantly available and thus provide a viable option for use as sound absorbing materials. In this study, fibres extracted from the bark of Himalayan Nettle (Girardinia diversifolia L.) were used to prepare nonwoven webs using needle punching technique. Punch density was varied to create webs with variable properties. The effect of punch density on acoustic properties was studied. A positive correlation was observed between sample thickness and the Noise Reduction Coefficient. Samples having punch density of 75needles/cm2 showed the highest Noise Reduction Coefficient, attributable to their greater porosity and lower compactness. The study demonstrates that the morphological traits of the Himalayan nettle fibre, that is, a rough surface, flat elliptical cross-section, and a hollow core, make it an excellent sound absorption material. The acoustic properties can be tuned by varying the properties of the nonwoven web.

Research on boiling heat transfer of aqueous extracts vacuum drying based on fractal theory

Traditional Chinese Medicine (TCM) aqueous extracts are highly viscous pseudoplastic porous media that boiling during vacuum drying, and the drying mechanism significantly differs from that of conventional solid materials. To reveal the heat transfer mechanism, a simulation model of aqueous extracts nucleate boiling was built based on fractal theory, and the effects of superheat, material temperature, viscosity and contact angle on fractal characteristics and heat transfer were studied. Results demonstrate that within a superheat range from 11 °C and 74 °C, the fractal dimension of active nucleation sites on the drying wall ranges between 1.75 and 1.86. The nuclear boiling heat flux increases with the increase in superheat, material temperature, specific heat capacity, thermal conductivity, and contact angle; or with the decrease in viscosity. The research can offer theoretical guidance for the development of drying processes and the optimization of technology in high viscosity pseudoplastic porous media.

Designing hybrid aerogel-3D printed absorbers for simultaneous low frequency and broadband noise control

Recent studies have demonstrated that granular aerogels with sub-50 μm particles surpass conventional acoustic materials like glass fibers and polyurethane foams in low-frequency sound absorption. However, incorporating such granular materials within practical structural solutions remains a challenge. In this study, we use additive manufacturing to overcome this challenge by designing a modular geometry that allows us to encapsulate such granular materials within a 3D printed scaffold. Using the 3D printed porous scaffold provides the added benefits of tunability and durability. Further, we introduce a design methodology and software tool to facilitate the efficient design of such hybrid sound absorbers. The proposed method uses the Johnson-Champoux-Allard model, Biot theory, and the transfer matrix method to model the acoustical behavior of hybrid absorber designs that use layered granular aerogels and 3D printed bulk absorbers. The tool can also be used to inversely characterize the acoustic bulk properties of such materials. We validate the design concept and tool by comparing the model predictions with experimental measurements. Finally, we outline strategies for designing hybrid absorbers that can provide application specific low-frequency and broadband absorption performance within specific frequency ranges, while considering engineering constraints on their total mass and depth.

Application and Future Utilization of Shellac in Orthodontics: A Systematic Review.

Background: This review examines the application of shellac in orthodontics, focusing on its properties, advantages, and potential as an alternative to conventional materials. In orthodontics, where bond strength, ease of application, and removal are paramount, shellac's capabilities meet these needs while supporting environmentally friendly practices. Methods: With objectives centered on evaluating shellac's effectiveness, biocompatibility, and impact on patient outcomes, a comprehensive search across multiple databases was conducted, including PubMed, Scopus, and Web of Science. This study's selection criteria targeted studies assessing shellac's use in orthodontic applications, measuring treatment effectiveness, biocompatibility, and patient satisfaction while excluding those not directly involving orthodontic applications or lacking empirical data. Results: Through a qualitative synthesis of the extracted data-encompassing study design, sample size, treatment outcomes, and adverse effects-the findings reveal shellac's potential benefits in orthodontics, such as enhanced patient comfort and comparable treatment outcomes to traditional materials. However, the review also notes variability in study designs and outcomes, indicating the need for further research. Conclusions: This study concluded that shellac presents a promising alternative in orthodontic materials, recommending additional studies to standardize assessment methodologies and confirm its long-term advantages.

Multi-method examination of contact mechanics in orthotropic layers under gravity

Analyzing the behavior of intelligent unconventional materials under diverse contact scenarios, in comparison to conventional materials, is a critical step in the initial design of engineering systems. This paper presents the development of analytical and numerical approaches for analyzing contact mechanics in a system comprising an orthotropic layer resting on a rigid foundation. Parametric analyses include the consideration of cylindrical and flat punch profiles. Analytical formulation utilizes integral transform methods to convert planar elasticity equations into a Cauchy-type singular integral equation of the second kind. A detailed description of the solution technique for the integral equation is provided, encompassing both the analytical formulation and the required discretization for obtaining the solution. Subsequently, a finite element approach (FEA) is employed to approximate contact bodies using a collection of finite elements, while contact boundaries are approximated by utilizing a set of polygons. Alternatively, the problem is addressed using the Multilayer Perceptron approach, a form of artificial neural network frequently applied in diverse machine learning applications, including scenarios involving contact problems. Finally, the resolution to the problem is achieved by employing the multilayer perceptron (MLP) method. The study yields determinations of contact stresses under the punch, the critical separation load resulting in the detachment of the orthotropic layer from the rigid foundation, and the corresponding separation distance. This analysis considers a range of dimensionless parameters and explored the behavior of diverse orthotropic materials. Comparisons between the results of the analytical method and computations from FEA and MLP reveal the exceptional accuracy attained by all three approaches. As the pioneer study employing three distinct approaches to examine continuous contact mechanics within an orthotropic layer under the influence of gravity, this research constitutes a valuable point of reference for upcoming scholars in the field.

Study on Mechanical Properties of Polymer Composites Filled with Nano Egg-shell Powder

Polymeric materials, when reinforced with synthetic fibers like glass, carbon, and aramid, offer notable advantages including increased stiffness and strength-to-weight ratio compared to conventional materials such as wood, concrete, and steel. Among these options, glass fiber stands out due to its affordability and widespread availability. Glass fiber reinforced polymer composites exhibit moderate mechanical properties, which can be significantly enhanced by incorporating nano fillers like eggshell powder. This study explores the utilization of nano eggshell powder as well as methods for effectively integrating nano fillers into polymer composites to create value-added products. Four types of composites, varying in weight proportions of nano eggshell powders, were prepared using the hand lay-up technique for mechanical and thermal characterizations. Various mechanical properties including tensile strength, flexural strength, impact behavior, as well as thermal properties via TGA and DMA analysis were investigated. The results indicate that incorporating the optimal amount of nano fillers significantly improves the overall strength of glass fiber reinforced composite materials, leading to cost savings of over 30%. This suggests that nano eggshell fillers hold great potential in composite manufacturing, particularly for substituting high-cost glass fibers in low load-bearing applications.

EFFECT OF VARIOUS CHEMICAL TREATMENTS ON PHYSICOCHEMICAL AND THERMAL PROPERTIES OF ERYTHRINA VARIEGATA FIBERS: APPLICATION IN EPOXY COMPOSITES

Recently, there has been an increasing trend in utilizing lignocellulosic fiber reinforced composites in structural applications within the construction and automobile industries, replacing conventional materials based on metals and their derivatives. In the present study, Erythrina variegata fibers (EVFs) were subjected to a number of chemical treatments individually (alkalization, benzoyl peroxide, potassium permanganate, and stearic acid treatments). The effects of these chemical treatments on the EVFs were examined through chemical composition analysis, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). This comprehensive analysis aimed to assess the suitability of the chemically treated EVFs for use as reinforcement in thermoset polymer matrix composites. The alkali treated fibers (AEVFs) were found as optimum and were then used as reinforcement in epoxy adhesives. Different fiber loadings (0, 5, 10, 15, 20, and 25 wt%) were incorporated into the epoxy matrix to investigate their effects on the properties of the composites. Therefore, the tensile strength, flexural strength, impact strength, and thermal stability of the prepared composites were evaluated under controlled laboratory conditions. The findings collectively suggested that the epoxy composites reinforced with 20 wt% of AEVFs exhibited promising characteristics for lightweight structural applications.

Nickel-rich ternary cathode material as a novel capping layer to improve lithium iron phosphate electrochemical performance

We use a facile high-temperature solid-phase method to coat a layer of Ni-rich ternary material (LiNi0.8Co0.1Mn0.1O2) on the surface of lithium iron phosphate. This active coating greatly improves the intrinsic conductivity of LiFePO4. Compared to the conventional carbon material cladding, since this cladding layer is electrochemically active, the problem of decreasing the proportion of active material due to the addition of a cladding layer can be avoided to a certain extent. Compared with the samples capped with conventional organic carbon source (151.2 mAh g−1) and inorganic carbon source (155.9 mAh g−1) at 0.2 C, the discharge specific capacity was as high as 165.7 mAh g−1. Capacity retention after 200 cycles is up to 98 %, which is much higher than that of glucose and graphene oxide (GO)-coated samples (95.9 %, 96.6 %). Even when charging and discharging cycles are performed at different multipliers (2C and 10C), the retention rate remains higher than the latter.

Magnetic vortex control with current-induced axial magnetization in centrosymmetric Weyl materials

We consider magnetic Weyl metals as a platform to achieve current control of magnetization textures with transport currents utilizing their underlying band geometry. We show that the transport current in a Weyl semimetal produces an axial magnetization due to orbital magnetic moments of the Weyl electrons. The associated axial magnetization can generate a torque acting on the localized magnetic moments. For the case of a magnetic vortex in a nanodisk of Weyl materials, this current-induced torque can be used to reverse its circulation and polarity. We discuss the axial magnetization torques in Weyl metals on general symmetry grounds and compare their strength to current-induced torques in more conventional materials.

Experimental Study on the Gelling Properties of Nano-Silica Sol and Its Spontaneous Imbibition Grouting Mudstone

The low-permeability argillaceous rock mass is an unfavorable geological body commonly found in the construction process of underground engineering conditions such as roadways and tunnels. Due to the compact structure and low permeability of the rock mass, grouting with conventional materials cannot effectively seal the micro-cracks of the rock mass. Based on the low efficiency of high-pressure grouting of nano-silica sol, this paper preliminarily explores the regularities and mechanism of grouting and pore sealing of low-permeability rock mass under the action of silica sol imbibition from the aspects of gelling properties of silica sol, core pore structure, imbibition law, and pore sealing characteristics. The results show the following: (1) The increase in particle size during the gel process reduced the injectability and wettability of the silica sol. The imbibition properties of silica sol were time-varying, and the deterioration inflection points of injectability and wettability appeared at 10 h and 9 h, respectively. (2) Catalyst, temperature, gel process, and rock mass permeability will affect the law of core imbibition, and the injectability and capillary force of the grouting material and rock mass will jointly affect the imbibition process of silica sol. (3) Silica sol imbibition changed the pore size distribution of the core, the pore volume above 50 nm decreased, and the pore volume below 50 nm increased. Silica sol has multiple effects such as filling, adsorption, and percolation in the imbibition process of the micro-pores of rock mass, and the adsorption and percolation of silica are related to the nano micro-pores.