Science China Technological Sciences最新文献

The field modulation effect has been proposed and investigated in various electric machine topologies. Among them, permanent magnet vernier machines (PMVMs) have attained intensive research due to the high torque density and simple structure. However, the performance of PMVMs in terms of fault tolerance is seldom mentioned. This article proposes a novel dual 3-phase fault-tolerant PMVM with segregated concentric windings. Benefiting from the field modulation effect, the PMVM can generate high torque with low PM flux. The low PM flux also implies small fault currents in the short-circuit case. Therefore, the PMVM exhibits inherent good fault-tolerant capability without sacrificing torque performance. Two independent 3-phase modular winding sets are adopted to improve redundancy. To realize the physical and electrical isolation, each winding set is controlled by a standard 3-phase inverter. The healthy performance and fault tolerance of the proposed machine are evaluated by finite element analysis and verified by experimental tests. The results infer its advantages in healthy conditions and various fault scenarios, including open-circuit, short-circuit, and interturn short-circuit conditions.

As the most abundant living entities in the environment, viruses have been well recognized as crucial members in sustaining biogeochemical cycling. However, the significance of viruses in soil ecosystem multifunctionality remains under-explored. In this study, we used metagenomics and meta-viromics analysis to investigate the role of soil viruses in soil ecosystem functions under heavy, light, and no organochlorine pesticides (OCPs) contamination. In the three types of soil samples collected, light-contaminated soils supported the highest level of multifunctionality, followed by heavy-contaminated soils and clean soils. Additionally, our results revealed a positive correlation between bacterial community evenness and multifunctionality index (p < 0.05). Dominant bacterial species with biodegradation and stress resistance advantages exhibited higher abundance in OCP-affected soils, potentially playing a core functional supporting role. Furthermore, our results indicated that the species richness and diversity of bacteriophages were positively correlated with multifunctionality (p < 0.05) in OCP-affected soils. Bacteriophages in OCP-affected soils regulate host metabolism and enhance soil ecosystem multifunctionality by infecting functional bacterial hosts and encoding AMGs related to soil element cycling. Our findings emphasize the potential effect of phages on ecosystem multifunctionality in contaminated soil, suggesting that phages may serve as contributors to soil ecology beyond bacteria and other microorganisms. Therefore, in polluted or constrained soils, further research could potentially translate phage communities and related ecological processes into artificial methods for application in soil pollution remediation or ecological restoration.

Hydrogel stands out as one of the most attractive wound dressings due to its excellent moisturizing properties and capacity to absorb wound exudates. However, conventional hydrogel dressings often lack responsiveness to the microenvironment, merely acting as protective barriers for the wound. Consequently, they exhibit limited effectiveness in preventing infection and facilitating wound repair. To address these problems, we have developed a multifunctional injectable hydrogel, CF/MS@HG, based on peroxidase-like nanozymes, aiming at rapidly healing bacterial-infected wounds. The hydrogel is mainly composed of oxidized sodium alginate, aminated gelatin, and polylysine, encapsulating MIL-101(CuFe) NPs (CF) and manganese selenide nanoparticles (MnSe₂ NPs, or MS NPs). After injection, the complex rapidly gelatinizes at the infected wound site through a Schiff base reaction. In vitro experiments have demonstrated the hydrogel’s strong adhesion and self-healing capabilities. Moreover, CF exhibiting peroxidase (POD)-like activity, catalyzes in situ hydrogen peroxide (H₂O₂) to generate highly toxic hydroxyl radicals (·OH) within the wound microenvironment, inducing oxidative damage to bacteria. Meanwhile, MS decomposes into H₂Se in the slightly acidic wound microenvironment, disrupting bacterial metabolism and inhibiting proliferation. The addition of polylysine further enhances the hydrogel’s antibacterial properties. In vivo experiments have shown that the hydrogel exhibits excellent biological safety and significantly promotes wound healing. This multifunctional smart hydrogel holds great promise for the treatment of bacterial-infected wounds.

Passive daytime radiative cooling (PDRC) technology has great potential in reducing cooling energy consumption. In order to further improve the spectral performance of PDRC coatings, current researchers mostly focus on the selection and size design of functional particles, while ignoring the optical properties enhancement effect caused by the interlayer binder. In this study, based on the principle that the refractive index difference between layers enhanced the backscattering performance of the solar spectrum, we proposed and manufactured a double-layer PDRC coating with polyvinylidene difluoride (PVDF) as the film-forming material in the upper layer and polydimethylsiloxane (PDMS) as the film-forming material in the lower layer, both filled with Al₂O₃ and SiO₂ particles. The double-layer PDRC coating exhibited excellent spectral performance that a high solar reflectivity of 98% and an emissivity of 0.95 at the “atmospheric window” band. In comparison, the solar spectrum reflectivity of the single-layer PDRC coatings based on PVDF and PDMS of the same thickness was 95% and 94.7%, respectively. Outdoor tests showed that the PDRC coating achieved a temperature decrease of up to 7.1°C under direct sunlight at noon time. In addition, the PDRC coating had excellent weather resistance, water resistance, and other basic properties. This article opens up a new idea and provides methodological guidance for the design of double-layer PDRC coatings.

It is urgently demanded to develop biomaterials with balanced hemostatic/antibacterial ability and facile preparation methods. In this work, cationic starch microparticles (MSQP), prepared by the facile grafting of microporous starch particles (MS) with tunable quaternized polyethyleneimine, were readily constructed as promising hemostatic materials for integrated antibacterial and hemostatic performance. The cationic grafts not only endowed MSQP with good antibacterial ability, but also benefited from biocompatible MS to achieve favorable biocompatibility. Moreover, in vitro results confirmed the superior hemostatic property of MSQP2 (with the medium content of cationic grafts) among three MSQP and pristine MS. After investigating the blood-material interactions of MSQP/MS, the procoagulant mechanism of MSQP2 was revealed that the optimal amount of cationic grafts achieves highly balanced plasma-protein adhesion, platelet adhesion and blood coagulation system. In vivo artery-injury model further demonstrated the superior hemostatic performance of MSQP2 for potential severe hemorrhage. This work sheds light on the design of cationic polymer-based biomaterials for balanced antibacterial and hemostatic functions.

Chlorinated organic compounds are emerging pollutants of widespread concern because of their toxicity, bioaccumulation, persistence, and lack of adequate regulatory measures. Their abiotic transformation, facilitated by iron-bearing minerals, is critical to their natural dissipation in soils and sediments. However, further exploration is needed to understand their underlying mechanisms and potential engineering applications under different redox conditions. This paper reviews the abiotic transformation behaviors and mechanisms of chlorinated organics at the active surface of iron-bearing minerals under anoxic and oxic conditions and summarizes the strategies for enhancing the abiotic transformation efficiency of chlorinated organics. The abiotic transformation rate under oxic conditions can be a few orders of magnitude higher than that under anoxic conditions. Under anoxic conditions, chlorinated organics undergo reductive dechlorination through reductive elimination, hydrogenolysis, dehydrohalogenation, and nucleophilic substitution. A close relationship between the abiotic transformation of chlorinated organics and the production of hydroxyl radicals by iron-bearing minerals under oxic conditions was discovered. Synthetic active iron-bearing minerals, carbonaceous materials, and biological synergy can facilitate abiotic dechlorination under anoxic conditions. Meanwhile, the regulation of redox conditions, the introduction of ligands, and the utilization of coexisting anions are proposed to enhance oxidative degradation. This study is expected to improve the comprehension of the abiotic degradation of chlorinated organics mediated by iron-bearing minerals and provide the theoretical foundation for developing new approaches aimed at addressing chlorinated organic pollution.

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) have recently gained considerable attention due to their potential risks to human health and ecosystems. The response to these concerns has led to regulations and bans on legacy PFASs, such as perfluorooctanoic acid and perfluorooctane sulfonic acid. Thus, fluoride production has shifted toward short-chain PFASs and emerging fluorinated alternatives. Several technologies are available for PFAS degradation, among which electrochemical oxidation (EO) is a promising method to mineralize legacy PFASs and other emerging fluorinated alternatives in water treatment. This review provides an overview of the recent advancements in EO, comprehensively elucidating PFAS degradation mechanisms at the anode and exploring key factors that influence PFAS removal efficiency, such as anode materials as well as reactor designs and configurations. Moreover, the review elucidates the impact of operating conditions and parameters, including current density, electrolytes, pH, initial PFAS concentrations, and other coexisting pollutants, on the EO process. Finally, the constraints in the EO process are discussed when considering practical implementations, including undesired by-product generation, incomplete mineralization resulting in the accumulation of short-chain PFASs, and low PFAS concentrations in the natural environment leading to mass transfer limitations and low defluorination efficiency. Consequently, this review provides a perspective on potential solutions integrating the pre-concentration steps and EO process for effective PFAS remediation.

With long-term production and widespread application, per- and polyfluoroalkyl substances (PFAS) have been detected in various media worldwide, including the atmosphere. Since the gradual restriction and phase-out of C₈ perfluoroalkyl acids (PFAAs), environmental contamination by emerging PFAS substitutes such as short-chain PFAA homologues, perfluoroether carboxylic, and sulfonic acids has been reported. Although there has been extensive monitoring of emerging PFAS substitutes in the aquatic environment, few studies have conducted target analysis and nontarget screening (NTS) of emerging unknown PFAS in the atmosphere over the past decade. To fill the gap, this review focused on emerging PFAS in the atmosphere in addition to legacy PFAS. The reported sampling, pretreatment, and instrumental analysis methods for target analysis and NTS of both neutral and ionic PFAS in the atmosphere are summarized, along with the advantages and current limitations of different sampling and NTS methods for PFAS in the atmosphere. The global levels, composition, and spatiotemporal distribution characteristics of legacy and emerging PFAS in the atmosphere are summarized and their transport, transformation, and dry/wet deposition are elucidated. The review highlights the importance of developing and applying the all-in-one strategy integrating target, suspect screening, and NTS to gain insights into emerging PFAS in the atmosphere and provide a reference for future research.

High-performance automotive thermal management systems with environment-friendly refrigerants are essential for achieving carbon peaking and carbon neutrality goals. In this study, an R290 vapor-injection heat pump system for electric vehicles is developed and experimentally investigated. The effects of refrigerant charge mass, injection pressure, and in-cabin air temperature are analyzed in ambient temperatures from −30°C to 0°C. The results show that the vapor-injection system can increase the coefficient of performance (COP) and heating capacity by 14.3% and 15.9% at 0°C/20°C (ambient/in-cabin temperature) compared with the basic system, and this increase becomes more significant at −20°C/20°C with improvements of 32.5% and 38.1%, respectively. At a lower ambient temperature of −20°C, increasing refrigerant charge mass contributes to a more pronounced increase in heating capacity than at 0°C, which results from the more significant increase in injection mass flow. The optimal COP at various injection pressures are 2.07 and 1.63 at 0°C and −20°C ambient temperatures, corresponding to the relative injection pressures of 0.60 and 0.57, and the injection flow ratios of 0.23 and 0.29, respectively. At −30°C/0°C, a COP of 1.69 can be achieved.

Chlorinated organic pollutants (COPs), both emerging and traditional, are typical persistent pollutants that harm soil health worldwide. Dechlorinators mediated reductive dechlorination is the optimal way to completely remove COPs from anaerobic soil through a redox reaction driven by electron transfer during microbial anaerobic respiration. Generally, the dechlorinated depletion of COPs in situ often interacts with multiple element biogeochemical activities, e.g., methanogenesis, sulfate reduction, iron reduction, and denitrification. Elucidating the relevance of biogeochemical cycles between COPs and multiple elements and the coupled mechanisms involved, thus, helps to develop effective pollution control strategies with the balance between pollution degradation and element cycles in heterogeneous soil, ultimately contributing to “one health” goal. In this review, we summarized the microbial-chemical coupling redox processes and the driving factors, elucidated the interspecies metabolites exchange and electron transfer mechanisms within COP-dechlorinating communities, and further proposed a detailed design, construction, and analysis framework of engineering COP-dechlorinating microbiomes via “top-down” self-assembly and “bottom-up” synthesis to pave the way from laboratory to practical field application. Especially, we delve into the major challenges and perspectives surrounding the design of state-of-the-art synthetic microbial communities. Our goal is to improve the understanding of the microbial-mediated coupling between reductive dechlorination and element biogeochemical cycling, with a particular focus on the implications for health-integrated soil bioremediation under the “one health” concept.