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A novel tripartite generative adversarial network (TripartiteGAN) and a covert communication method based on TripartiteGAN were designed for jointly optimizing the transmission covertness and the demodulation accuracy of the covert message.The performance of the method was analyzed.Specifically, TripartiteGAN was used to manipulate the amplitude and phase of an input modulated covert data so that the distribution of the generated covert signal superposing the overt signal approximates to that of the overt signal for the public user.The proposed method could work with an optimum warden that needs neither to set the detection threshold manually nor to know the transmit power characteristics of the sender.Simulation results show that under the additive white Gaussian noise channel, the proposed TripartiteGAN improved the demodulation accuracy at the covert receiver end while keeping the probability of regarding the detected signal as the covert one or the overt one at the warden around 0.5.Moreover, the proposed method outperforms the existing covert communication scheme based on generative adversarial network (GAN).

Low Earth Orbit (LEO) satellite communications can provide global coverage in the sixth generation communication (6G) networks. To combat the strong Partial Band Interferences (PBIs) and multipath fading in LEO satellite communication systems, the Multicarrier Direct Sequence Code Division Multiple Access (MC-DS-CDMA) technique is a promising alternative to the traditional Single-carrier Direct Sequence Code Division Multiple Access (SC-DS-CDMA) system for its advantages of high bandwidth efficiency, superior interference rejection capability, and low complexity of parallel signal processing. However, limited studies have been conducted on the performance analysis of MC-DS-CDMA acquisition systems in the presence of a large Doppler shift, a unique characteristic of LEO satellite communications. To bridge this gap, we investigate the performance of MC-DS-CDMA systems with two-dimensional acquisition and noncoherent equal gain combining over Rician fading channel in the presence of the Doppler shift and PBIs. The performance metrics are detection probability and Mean Square Error (MSE) of the Doppler factor and delay. Specifically, we derive the closed-form expressions for the MSE and the Probability Density Function (PDF) of the acquisition decision variable and obtain the detection probability. We conduct extensive numerical experiments to verify the theoretical analysis and performance gain of MC-DS-CDMA over the SC-DS-CDMA. The results show that MC-DS-CDMA with two-dimensional acquisition is more robust to multipath Rician fading than SC-DS-CDMA. Moreover, MC-DS-CDMA outperforms SC-DS-CDMA regarding the detection probability and MSE when combating the strong PBIs.

Abstract Deoxygenation of bioderived lipids into renewable transportation fuels is a promising route to decreasing the dependence on fossil sources. Ni-based catalysts are high performing and cost-effective in deoxygenation reactions but suffer from severe sintering and aggregation. Herein, a ligand-chelating impregnation method was used to prepare highly dispersed Ni nanoclusters on a two-dimensional (2D) ITQ-2 zeolite. Comprehensive characterization was utilized to monitor the changes in the organometallic precursors during activation and to investigate their impact on the dispersion of the Ni nanoclusters on the ITQ-2 zeolite. The high external surface area and abundant surface defects of the 2D support enhanced the dispersion and immobilization of the Ni nanoclusters and outperformed conventional zeolites. The protection of the Ni2+ cations by the organic ligand suppressed the aggregation of Ni species during the activation processes, thereby leading to the formation of uniformly distributed Ni nanoclusters on the ITQ-2 zeolite. Due to the highly dispersed Ni nanoclusters and immobilization on the 2D zeolite, the Ni/ITQ-2-co material prepared by the ligand-chelating impregnation approach showed outstanding activity and stability for conversions of stearic acid or palm oil to diesel range alkanes. This work provides a rational design and precise modulation of metal-based catalysts for the production of renewable diesel.

The excessive utilization of petroleum diesel has led to the depletion of fossil resources and severe environmental pollution. Biodiesel produced from renewable triglycerides (TGs) or waste lipids is a low-emission fuel substitute for diesel. Biodiesel is mainly produced by transesterification reactions over homogeneous base catalysts with excellent activity and low cost. In comparison, solid base catalysts are more attractive due to their lower environmental impact and simpler production and purification processes. It remains a challenge to further improve the stability and activity of solid base catalysts. Because of the high surface area, superior stability, and tunable basicity, basic zeolites, especially two-dimensional zeolites, have emerged as promising solid basic catalysts for the transesterification of TGs. In this review, we present recent advancements in the synthesis, characterization, and catalytic performance of basic zeolites for the transesterification of TGs. Challenges and development prospects of basic zeolites for biodiesel production via transesterification are also pointed out. We expect that this review will inspire the more efficient and rational design of zeolites for sustainable fuel production.

The exploration of highly efficient catalysts based on nano-sized Ti-rich titanosilicate zeolites with controllable active titanium species is of great importance in zeolite catalytic reactions. Herein, we reported an efficient and facile synthesis of nano-sized Ti-rich TS-1 (MFI) zeolites by replacing tetrabutyl orthotitanate (TBOT) with tetrabutyl orthotitanate tetramer (TBOT-tetramer) as the titanium source. The introduced TBOT-tetramer slowed down the zeolite crystallization process, and accordingly balanced the rate of incorporating Ti and the crystal growth and inhibited the massive formation of anatase species. Notably, the prepared Ti-rich TS-1 zeolite sample had a Si/Ti as low as 27.6 in contrast to conventional one with a molar ratio of 40. The TBOT-tetramer endowed the titanosilicate zeolites with enriched active titanium species and enlarged external surface area. It also impeded the formation of anatase species, resulting in superior catalytic behavior toward the oxidative desulfurization of dibenzothiophene compared with the conventional TS-1 zeolite counterpart prepared with TBOT.

Purpose: There is growing evidence that genetic factors can influence human athletic performance. In many sports performances, excellent coordination and agility are the keys to mastery. However, few studies have been devoted to identifying genetic influences on athletic performance. Methods: We generated a derived measure of coordination and agility from the data of hexagonal jumps and T-runs and conducted genome-wide association and meta-analysis studies focused on coordination and agility. Results: The phenotypic correlation and genetic covariance analysis indicated that hexagonal jumps and T-runs were possibly influenced by the same set of genetic factors (R = 0.27, genetic covariance = 0.59). Meta-analysis identified rs117047321 genome-wide significant association (N = 143, P

The Sixth-Generation (6G) standard for wireless communications is expected to realize ubiquitous coverage for massive Internet of Things (IoT) networks by 2030. Satellite-based communications are recognized as a highly promising technical enabler to satisfy IoT service requirements in the 6G era. This study analyzes multiple access technologies, which are essential for the effective deployment of satellite-based IoT. First, we thoroughly investigate the existing research related to massive access, including information-theory considerations as well as Non-Orthogonal Multiple Access (NOMA) and Random Access (RA) technologies.Then, we explore the influence of the satellite transmission environment on multiple access technologies. Based on this study, a Non-orthogonal Massive Grant-Free Access (NoMaGFA) scheme, which reaps the joint benefits of RA and NOMA, is proposed for asynchronous transmissions in satellite-based IoT to achieve improved system throughput and enhance the system robustness under varying traffics. Finally, we identify some important and interesting future developments for satellite-based IoT, including waveform design, transceiver design, resource allocation, and artificial intelligence-enhanced design.

The resource scheduling problem of satellite communication systems under the condition of high-dynamic and resource limitation was studied.A resource scheduling model for satellite communication systems was established based on time window, energy consumption, number of channels, user priority and task suddenness.Considering the disadvantages of slow initial search speed and weak local search ability, the improved ant colony algorithm based on construction of initial solution set and extra pheromone deposition was proposed to solve the resource scheduling problem.The optimization characteristics of the number of completed tasks, priority and scheduling completion time were simulated and analyzed.The results show that the algorithm has a fast convergence rate.Compared with the same type optimization algorithm, the algorithm has high scheduling efficiency, therefore, it is suitable for scheduling satellite communication system resources for multi-beam dense networking in the future.

Basic zeolites have shown great potential as efficient catalysts for biodiesel production in the transesterification reactions. However, conventional three-dimensional (3D) basic zeolites generally suffer from limited base sites and severe mass-transfer restriction, thereby suppressing their catalytic activity. Herein, 2D basic zeolites with large external surface areas, hierarchical characteristics, and abundant accessible and stable base sites are prepared by expansion, delamination and subsequent solid-state ion-exchange (SSIE) approach. The facile SSIE method provides more advantages in stabilizing and dispersing high concentration of strong basic sites than the conventional liquid-phase ion-exchange (LIE) approach. Due to the excellent mass transportation and stable basic sites, the 2D Na/ITQ-2 prepared by the SSIE approach shows remarkably enhanced activity and recyclability in the transesterification of triglycerides to produce biodiesel, compared to 3D zeolites and other reported basic zeolites. This work will open the boulevard to the rational design of 2D basic catalysts and expand the potential application of 2D zeolites to biodiesel production and other industrial reactions involving bulky molecules.

Mobile edge computing (MEC) brings a breakthrough for Internet of Things (IoT) for its ability of offloading tasks from user equipments (UEs) to nearby servers which have rich computation resource. 5G network brings a huge breakthrough on transmission rate. Together with MEC and 5G, both execution delay of tasks and time delay from downloading would be shorter and the quality of experience (QoE) of UEs can be improved. Considering practical conditions, the computation resource of an MEC server is finite to some extent. Therefore, how to prevent the abuse of MEC resource and further allocate the resource reasonably becomes a key point for an MEC system. In this paper, an MEC system with multi-user is considered where a base station (BS) with an MEC server, which can not only provide computation offloading service but also data cache service. Especially, we take the charge for both data transmission and task computation as one part of total cost of UEs, and then explore a joint optimization for downlink resource allocation, offloading decision and computation resource allocation to minimize the total cost in terms of the time delay and the charge to UEs. The proposed problem is formulated as a mixed integer programming (MIP) one which is NP-hard. Therefore, we decouple the original problem into two subproblems which are downlink resource allocation problem and joint offloading decision and computation resource allocation problem. Then we address these two subproblems by using convex and nonconvex optimization techniques, respectively. An iterative algorithm is proposed to obtain a suboptimal solution in polynomial time. Simulation results show that our proposed algorithm performs better than benchmark algorithms.

The large-scale application of intermittent renewable energy has boosted the prosperous development of secondary batteries for the past several decades. In comparison with batteries based on liquid electrolytes, solid-state batteries are regarded as the goal for future energy storage due to their superior safety, nonvolatilization, excellent mechanical strength, and high energy density. While conventional solid electrolytes (SEs) struggle with their intrinsic limitations, zeolites are emerging as a promising choice for the future SEs of solid-state batteries. Herein, first, we analyze the challenges faced by conventional SEs to highlight the significance of leveraging zeolite-based SEs in secondary batteries. Then, we discuss the application of zeolites in liquid and solid electrolytes and showcase the functions of zeolites contributing to the enhanced wettability, thermal stability, mechanical strength, electrochemical stability, and ionic conductivity of separators and/or SEs. Finally, we provide a perspective on the development directions for zeolite-based SEs toward the design of materials, extension of battery systems, investigation of the conductive mechanism, and their practical applications.

Separating immiscible liquids with small surface energy differences remains a challenge. Here, the authors develop a polarity-based strategy for the separation of multiphase mixtures of immiscible liquids, even those with surface energy differences as small as 2 mJ m-2.

Abstract 3D‐printing technology is a promising approach for rapidly and precisely manufacturing zeolite adsorbents with desirable configurations. However, the trade‐off among mechanical stability, adsorption capacity, and diffusion kinetics remains an elusive challenge for the practical application of 3D‐printed zeolites. Herein, a facile “3D printing and zeolite soldering” strategy is developed to construct mechanically robust binder‐free zeolite monoliths (ZM‐BF) with hierarchical structures, which can act as a superior configuration for CO2 capture. Halloysite nanotubes are employed as printing ink additives, which serve as both reinforcing materials and precursor materials for integrating ZM‐BF by ultrastrong interfacial “zeolite‐bonds” subjected to hydrothermal treatment. ZM‐BF exhibits outstanding mechanical properties with robust compressive strength up to 5.24 MPa, higher than most of the reported structured zeolites with binders. The equilibrium CO2 uptake of ZM‐BF reaches up to 5.58 mmol g−1 (298 K, 1 bar), which is the highest among all reported 3D‐printed CO2 adsorbents. Strikingly, the dynamic adsorption breakthrough tests demonstrate the superiority of ZM‐BF over commercial benchmark zeolites for flue gas purification and natural gas and biogas upgrading. This work introduces a facile strategy for designing and fabricating high‐performance hierarchically structured zeolite adsorbents and even catalysts for practical applications.

Abstract Taking advantage of the synergetic effect of confined ultrasmall metal clusters and zeolite frameworks is an efficient strategy for improving the catalytic performance of metal nanocatalysts. Herein, it is demonstrated that the synergetic effect of ultrasmall ruthenium (Ru) clusters and intrinsic Brønsted acidity of zeolite frameworks can significantly promote the hydrogen generation of ammonia borane (AB) hydrolysis. Ultrasmall Ru clusters are embedded onto the silicoaluminophosphate SAPO‐34 (CHA) and various aluminosilicate zeolites (MFI, *BEA, and FAU) with tunable acidities by a facile incipient wetness impregnation method. Evidenced by high‐resolution scanning transmission electron microscopy, the sub‐nanometric Ru clusters are uniformly distributed throughout the zeolite crystals. The X‐ray absorption spectroscopy measurements reveal the existence of Ru‐H species between Ru clusters and adjacent Brønsted acid sites of zeolites, which could synergistically activate AB and water molecules, significantly enhancing the hydrogen evolution rate of AB hydrolysis. Notably, the Ru/SAPO‐34‐0.8Si (Si/Al = 0.8) and Ru/FAU (Si/Al = 30) catalysts with strong acidities afford high turnover frequency values up to 490 and 627 min−1, respectively. These values are more than a 13‐fold enhancement than that of the commercial Ru/C catalyst, and among the top level over other heterogeneous catalysts tested under similar conditions.

In Table 1 of this Article, the third row in the furthest right column contains a typographical error and should read ‘NH’, rather than ‘NM’, corresponding to n-hexane as the infused liquid.