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Methyl orange (MO) is a common anionic azo dye that is harmful to the environment and biology, so it must be treated innocuously before it can be discharged. Adsorption is an effective method to remove anionic dyes. Nanotube mineral is a natural one-dimensional adsorption material, and its unique morphology and structure endow it with good adsorption capacity. Although there are many related studies, there is a lack of in-depth discussions on the influence of nanotube’s composition and structure on the adsorption of dyes and other pollutants. In this paper, two kinds of natural one-dimensional silicate minerals [halloysite nanotubes (HNTs) and chrysotile nanotubes (ChNTs)] with similar morphology but slightly different compositions and crystal structures were used as adsorbents, and MO solution was used as simulate pollutants. It is the first time to discuss in depth the influence of the composition and structure of nanotube minerals on their charge properties and the adsorption performance of methyl orange dyes. It is found that HNTs and ChNTs have different adsorption capacity due to the difference of electronegativity between Al 3+ and Mg 2+ in the crystal, so they possess negative and positive charges respectively in near-neutral solution, which leads to the adsorption capacity of MO by ChNTs with positive charges which is greater than that of HNTs.

Noisy permutation channels are applied in modeling biological storage systems and communication networks. For noisy permutation channels with strictly positive and full-rank square matrices, new achievability bounds are given in this paper, which are tighter than existing bounds. To derive this bound, we use the ϵ-packing with Kullback–Leibler divergence as a distance and introduce a novel way to illustrate the overlapping relationship of error events. This new bound shows analytically that for such a matrix W, the logarithm of the achievable code size with a given block n and error probability ϵ is closely approximated by ℓlogn−Φ−1(ϵ/G)+logV(W), where ℓ=rank(W)−1, G=2ℓ+12, and V(W) is a characteristic of the channel referred to as channel volume ratio. Our numerical results show that the new achievability bound significantly improves the lower bound of channel coding. Additionally, the Gaussian approximation can replace the complex computations of the new achievability bound over a wide range of relevant parameters.

The improper handling of smelting slag will seriously pollute the environment, and the unfilled roof of the goaf of the mine will threaten the safety of the mine. Expansion materials have attracted more and more attention because of their excellent properties. In this paper, copper-nickel smelting slag that has some active ingredients of gelling is used instead of traditional aggregate and some part of cement in order to reduce its pollution to the environment and its costs. For safety reasons, hydrogen peroxide was chosen as the foaming agent. Sodium silicate and hexadecyl trimethyl ammonium bromide (CTAB) are used as additives. Our results showed that after 28 days of curing, the material has better mechanical properties and the early compressive strength of the material was enhanced by sodium silicate. The efficiency of foaming was improved by CTAB. It also proves that copper–nickel smelting slag can be used in expansion material. At the same time, the utilization rate of the copper–nickel smelting slag of this formula can reach 70%, reduce its pollution to the environment.

Coal gangue, the primary solid by-product of coal mining, presents severe environmental challenges due to massive accumulation. At the same time, it represents potential as a secondary resource if properly utilized. This review systematically summarizes the mineralogical characteristics, modification strategies, and utilization pathways of coal gangue. Current treatment methods, including thermal, chemical, and microbial activation, are discussed, highlighting their respective efficiencies, economic feasibility, and environmental impacts. Furthermore, this review emphasizes the transition of coal gangue from low-value disposal to high-value utilization. Representative applications are summarized, including its use as a precursor for advanced construction materials, as a functional material for environmental remediation, and as a feedstock for energy recovery. Finally, the major technological challenges and research gaps are identified. Future development should focus on intelligent sorting technologies, low-carbon activation processes, and synergistic multi-waste integration. These directions are expected to promote the transformation of coal gangue from an environmental liability into a valuable resource for the circular economy.

Naturally occurring halloysite nanotubes (HNTs), a clay mineral characterized by a unique dual-charge architecture, offer a promising strategy for enhancing the performance of composite polymer electrolyte (CPE). In this work, HNTs are introduced as a low-cost, functional filler to simultaneously address two key limitations of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based CPE: low ionic conductivity and inadequate lithium-ion transference number. The negatively charged outer surface of HNTs facilitates Li+ transport, while the positively charged inner lumen confines anions such as TFSI−. Controlled acid etching (6 M HCl, 12 h) further optimizes this structure by removing surface impurities and enlarging the lumen, thereby enhancing both charge-directed ion transport pathways. The resulting HNT-modified CPE achieves a high ionic conductivity of 6.1 × 10−4 S⋅cm−1 and a Li+ transference number of 0.73. When assembled into Li||CPE||LiFePO4 cells, the electrolyte enables stable cycling over 300 cycles at 0.2C, retains 119.2 mAh/g at 2C, and delivers 85.7 mAh/g even at 5C, demonstrating excellent cycling stability and rate capability. This study reveals the potential of mineral-derived nanomaterials, with their inherent structural and physicochemical properties, to serve as key functional components in high-performance batteries.

In this paper, a cooperative orthogonal frequency division multiplexing system with multiple untrusted amplify‐and‐forward relays is considered. Since there exists no direct link between source and user because of the shadowing effect, a positive system secrecy rate cannot be obtained. Addressing this issue, a cooperative user‐aided jamming technique to improve the secrecy performance is employed. With the aim of maximising the system secrecy rate, a joint resource allocation problem of power allocation, relay assignment and subcarrier pairing is formulated. By using the signal‐to‐noise ratio based approach and the Lagrange dual method, this nonconvex problem is solved efficiently. To reduce the calculation complexity, a suboptimal algorithm, which decouples the power allocation with the relay assignment and subcarrier pairing is further proposed. Numerical results are presented to demonstrate the advantage of the two proposed algorithms and the impact of relays' location and number of subcarriers on the secrecy performance. Moreover, it is shown that the secrecy performance of the proposed scheme is decreased with respect to the number of untrusted relays.

The security issue of wireless communication is a common concern because of its broadcast nature, especially when the relay becomes an eavesdropper. In the orthogonal frequency division multiplexing (OFDM) relay system, when the relay is untrusted, the security of the system faces serious threats. Although there exist some resource allocation schemes in a single-carrier system with untrusted relaying, it is difficult to apply them to the multi-carrier system. Hence, a resource allocation scheme for the multi-carrier system is needed. Compared to the one-way relay system, a two-way relay system can improve the data transmission efficiency. In this paper, we consider joint secure resource allocation for a two-way cooperative OFDM system with an untrusted relay. The joint resource allocation problem of power allocation and subcarrier pairing is formulated to maximize the sum secrecy rate of the system under individual power constraints. To solve the non-convex problem efficiently, we propose an algorithm based on the alternative optimization method. The proposed algorithm is evaluated by simulation results and compared with the benchmarks in the literature. According to the numerical results, in a high signal-to-noise ratio (SNR) scenario, the proposed algorithm improves the achievable sum secrecy rate of the system by more than 15% over conventional algorithms.

The (110) facets of hematite have excellent adsorption performance for chromium. We aim to obtain hematite with a large specific surface area and exposed (110) facets by using natural needle-like goethite as the precursor. The derived hematite shows a significant increment in the removal capacity of chromium by six times compared with goethite under the same experimental conditions. Structural model fitting of extended X-ray absorption fine structure (EXAFS) spectroscopy suggested that the interatomic distance of Cr-Fe was approximately 3.6 Å for the Cr (VI) coordinated hematite with exposed (110) facets, which was characteristic of the form of bidentate binuclear surface complex. Molecular dynamic simulations for the arrangement of Cr (VI) in (110) facets of goethite and hematite indicated the superiority of hematite adsorption for chromium. We optimized efficient and economic permeable reactive barrier (PRB) materials by crystal plane adjustment based on these experimental and theoretical results. It was found that the life span of the column even reached 610 PVs when the initial concentration of Cr (VI) was 20 mg/L, which indicates its potential application in the field of PRB medium material.

In this study, a non‐orthogonal multiple access based cooperative relay system is investigated, where the source serves multiple destinations via an amplify‐and‐forward relay. Direct links between the source and destinations are considered to form a general framework while the maximum ratio combination (MRC) is applied to obtain the largest decoding signal‐to‐interference‐plus‐noise ratio (SINR). Firstly, the outage performance is analysed with given successive interference cancellation (SIC) order and power allocation. An excellent approximated expression for the exact outage probabilities is derived in closed form. In addition, the asymptotic expression at high signal‐to‐noise ratio is provided to gain further insights. Then, in order to fully exploit the potential of the system, a joint optimisation of SIC order design and power allocation is formulated, with the objective of minimising the maximum outage probability of all destinations. By exploring the inherent property of the system, an optimal solution of SIC order and power allocation is developed. Finally, simulation results are presented to verify the correctness of the analytical results as well as indicate the efficiency of authors' SIC order design and power allocation algorithm.

Metallic 1T MoS2 greatly benefits the supercapacitance of MoS2 due to its considerably higher conductivity as compared to semiconducting 2H MoS2. Alkali metals, such as Li, Na and K, are always used to prepare 1T MoS2 through intercalation of alkali metal ions into the interlayer of 2H MoS2. Nevertheless, the influences of the alkali-earth metals as the guest in the interlayer of MoS2 on its structure and electrochemical capacitor performance are rarely investigated. Herein, we introduced hydrated Mg ions as the guest into MoS2 nanosheets. The interlayer spacing was increased to 1.144 nm after the introduction of hydrated Mg ions, larger than that of the pristine MoS2 (0.620 nm) and restacking MoS2 (0.626 nm). The enlarged interlayer spacing can accommodate more ions during intercalation process. Moreover, the 1T phase concentration after the introduction of hydrated Mg ions was as high as ~ 90%, which benefits the charge transfer during the charging/discharging processes. Consequently, the specific capacitance of the MoS2 with Mg guest ions as well as the energy densities and power densities was greatly improved as compared to those of the restacking MoS2 or pristine MoS2 counterparts. The present work not only demonstrated a new strategy for engineering the physical properties and improving the electrochemical performance of MoS2 supercapacitor electrode through pre-intercalation of alkali-earth metal ions in the interlayer of MoS2, but also has directive significance for the design of other layered electrode materials for energy storage systems.