Collaborative unmanned systems have emerged to meet our society's wide-ranging grand challenges, with their advantages including high performance, efficiency, flexibility, and inherent resilience. Increasing levels of group/team autonomy have also been achieved due to the embodiment of artificial intelligence (AI). However, the current networked unmanned systems still do not have sufficient human-level intelligence and human needs fulfillment for the challenging missions in our lives. We propose in this paper a vision of human-centric networked unmanned systems: Unmanned Intelligent Clusters (UnIC). Within this vision, distributed unmanned systems and humans are connected via knowledge to achieve cognition. This paper details UnIC's concept, sources of intelligence, and layered architecture, and review enabling technologies for achieving this vision. In addition to the technological aspects, the social acceptance is highlighted.
Unmanned systems such as legged robots require fast-motion responses for operation in complex environments. These systems therefore require explosive actuators that can provide high peak speed or high peak torque at specific moments during dynamic motion. Although hydraulic actuators can provide a large force, they are relatively inefficient, large, and heavy. Industrial electric actuators are incapable of providing instant high power. In addition, the constant reduction ratio of the reducer makes it difficult to eliminate the tradeoff between high speed and high torque in a given system. This study proposes an explosive electric actuator and an associated control method for legged robots. First, a high-power-density variable transmission is designed to enable continuous adjustment of the output speed to torque ratio. A heat-dissipating structure based on a composite phase-change material (PCM) is used. An integral torque control method is used to achieve periodic and controllable explosive power output. Jumping experiments are conducted with typical legged robots to verify the effectiveness of the proposed actuator and control method. Single-legged, quadruped, and humanoid robots jumped to heights of 1.5, 0.8, and 0.5 m, respectively. These are the highest values reported to date for legged robots powered by electric actuators.
This article reports the development of a novel switchable Pickering emulsion with rapid CO2/N2 responsiveness, which is stabilized using alumina nanoparticles hydrophobized in situ with a trace amount of a switchable superamphiphile via electrostatic interactions. With the introduction of CO2 for 30 s, the Pickering emulsion can be spontaneously demulsified with complete phase separation; the emulsion can then be reconstructed in response to N2 purging for 10 min followed by homogenization. Moreover, the stable Pickering emulsion can be stored for more than 60 days at room temperature without any visible change. The CO2/N2-responsive behavior of the switchable Pickering emulsion is attributed to the reversible desorption/adsorption of the switchable surfactants on the surfaces of the alumina nanoparticles upon the alternative bubbling of CO2 or N2. Thanks to the simple fabrication of the surfactant and the hydrophobization of the alumina nanoparticles, this research has developed an extremely facile and cost-efficient method for preparing a rapidly CO2/N2-responsive switchable Pickering emulsion. The dosage of the switchable surfactants has been significantly reduced by nearly 1500 times (from 150 to 0.1 mmol∙L−1) as compared with the dosage used in previous studies. Moreover, the as-prepared CO2/N2-responsive switchable Pickering emulsion is environmentally friendly, mild, and nontoxic; thus, it holds great potential for practical applications with considerable economic and environmental benefits, such as oil transport, fossil fuel production, environmental gases detection, and the encapsulation and release of active ingredients.
In this study, current-induced partial magnetization-based switching was realized through the spin–orbit torque (SOT) in single-layer L10 FePt with a perpendicular anisotropy (Ku⊥) of 1.19 × 107 erg‧cm−3 (1 erg‧cm−3 = 0.1 J‧m−3), and its corresponding SOT efficiency (βDL) was 8 × 10−6 Oe∙(A‧cm−2)−1 (1 Oe = 79.57747 A‧m−1), which is several times higher than that of the traditional Ta/CoFeB/MgO structure reported in past work. The SOT in the FePt films originated from the structural inversion asymmetry in the FePt films since the dislocations and defects were inhomogeneously distributed within the samples. Furthermore, the FePt grown on MgO with a granular structure had a larger effective SOT field and efficiency than that grown on SrTiO3 (STO) with a continuous structure. The SOT efficiency was found to be considerably dependent on not only the sputtering temperature-induced chemical ordering but also the lattice mismatch-induced evolution of the microstructure. Our findings can provide a useful means of efficiently electrically controlling a magnetic bit that is highly thermally stable via SOT.
The chemical looping steam reforming (CLSR) of bioethanol is an energy-efficient and carbon-neutral approach of hydrogen production. This paper describes the use of a NixMg1−xO solid solution as the oxygen carrier (OC) in the CLSR of bioethanol. Due to the regulation effect of Mg2+ in NixMg1−xO, a three-stage reaction mechanism of the CLSR process is proposed. The surface oxygen of NixMg1−xO initially causes complete oxidation of the ethanol. Subsequently, H2O and bulk oxygen confined by Mg2+ react with ethanol to form CH3COO* followed by H2 over partially reduced NixMg1−xO. Once the bulk oxygen is consumed, the ethanol steam reforming process is promoted by the metallic nickel in the stage III. As a result, Ni0.4Mg0.6O exhibits a high H2 selectivity (4.72 mol H2 per mole ethanol) with a low steam-to-carbon molar ratio of 1, and remains stable over 30 CLSR cycles. The design of this solid-solution OC provides a versatile strategy for manipulating the chemical looping process.
The integration of additive manufacturing (AM) in design and engineering has prompted a wide spectrum of research efforts, involving topologically optimized solid/lattice structures, multimaterial structures, bioinspired organic structures, and multiscale structures, to name a few. However, except for obvious cases, very little attention has been given to the design and printing of more complex three-dimensional (3D) hollow structures or folded/creased structures. One of the main reasons is that such complex open or closed 3D cavities and regular/freeform folds generally lead to printing difficulties from support-structure-related issues. To address this barrier, this paper aims to investigate four-dimensional (4D) printing as well as origami-based design as an original research direction to design and build 3D support-free hollow structures. This work consists of describing the rough 3D hollow structures in terms of two-dimensional (2D) printed origami precursor layouts without any support structure. Such origami-based definitions are then embodied with folding functions that can be actuated and fulfilled by 3D printed smart materials. The desired 3D shape is then built once an external stimulus is applied to the active materials, therefore ensuring the transformation of the 2D origami layout to 3D structures. To demonstrate the relevance of the proposal, some illustrative cases are introduced.
Rett syndrome is a progressive neurodevelopmental disorder that lacks effective treatments. Although deep-brain stimulation can alleviate some symptoms in Rett model mice, this interventional manipulation requires deliberate surgical operations. Here, we report that electro-acupuncture stimulation (EAS) can ameliorate symptoms of an Mecp2-knockout rat model of Rett syndrome from the remote acupoints Baihui (GV 20), Yongquan (KI 1), and Shenmen (HT 7). We find that EAS not only prolongs the survival time of Rett rats, but also improves their behavior ability, including locomotion, motor coordination, and social interaction. Neural activation was observed in the substantia nigra of the midbrain, corpus striatum, and cerebral cortex of wild-type and Rett model rats, as reflected by the increased expression of the c-Fos protein. Hence, EAS provides a potential promising therapeutic tool for treating neurodevelopmental diseases.
Carbapenemase-producing Enterobacteriaceae (CPE) isolates are recognized as one of the most severe threats to public health. However, the population structure and genetic characteristics of CPE isolates among bloodstream infections (BSIs) are largely unknown. To address this knowledge gap, in this study, we included patients with clinically significant BSIs due to Enterobacterales isolates, recruited from 26 sentinel hospitals in China (2014–2015). CPE isolates were microbiologically and genomically characterized, including their susceptibility profiles, molecular typing, phylogenetic features, and genetic context analysis of carbapenemase-encoding genes. Of the 2569 BSI Enterobacterales isolates enrolled, 42 (1.6%) were carbapenemase-positive. Moreover, among the 2242 investigated isolates, 1111 (49.6%) extended-spectrum β-lactamase (ESBL)-producing isolates were identified in Escherichia coli (E. coli), Klebsiella pneumoniae (K. pneumoniae), Proteus mirabilis (P. mirabilis), and Klebsiella oxytoca. Whole genome sequencing analysis showed the clonal spread of K. pneumoniae carbapenemase (KPC)-2-producing K. pneumoniae sequence type 11 (ST11) and New Delhi metallo-β-lactamase (NDM)-5-producing E. coli ST167 in our collection. Plasmid analysis revealed that carbapenemase-encoding genes were located on multiple plasmids. A high prevalence of biofilm-encoding type 3 fimbriae clusters and yesiniabactin-associated genes was observed in K. pneumoniae isolates. This work demonstrates the high prevalence of ESBLs and the wide dissemination of CPE among BSI isolates in China, which represent real clinical threats. Moreover, our findings first illustrate a more comprehensive genome scenario of CPE isolates among BSIs. The clonal spread of KPC-2-producing K. pneumoniae ST11 and NDM-5-producing E. coli ST167 needs to be closely monitored.
The colonization of the human microbiota in early life has long-lasting health implications. The status of the initial intestinal microbiota determines human growth and development from infancy to adulthood, and thus represents a crucial window in our long-term development. This review aims to summarize the latest findings on the symbiotic gut microbiota early in life and its vital role in metabolic-, allergic-, and auto-immune-disorder-related diseases, including obesity, diabetes, allergy, autism, inflammatory bowel disease, and stunting. It discusses the development process and various factors shaping the gut microbiota, as well as the crosstalk between the gut microbiota and the host's physiological systems (especially intestinal immune development and homeostasis, and the central nervous system in the course of neurodevelopment), during the early life establishment of the gut microbiota, in order to decipher the mechanisms of diseases associated with the intestinal microbiome of early life. In addition, it examines microbiota-targeted therapeutic methods that show promising effects in treating these diseases. The true process of gut microbiome maturation, which depends on genetics, nutrition, and environmental factors, must be scrutinized in order to monitor healthy gut microbiome development and potentially correct unwanted courses by means of intervention via methods such as novel probiotics or fecal microbiota transplantation.
Riboflavin is an essential micronutrient for humans and must be obtained exogenously from foods or supplements. Numerous studies have suggested a major role of riboflavin in the prevention and treatment of various diseases. There are mainly three strategies for riboflavin synthesis, including total chemical synthesis, chemical semi-synthesis, and microbial fermentation, the latter being currently the most promising strategy. In recent years, flavinogenic microbes have attracted increasing attention. Fungi, including Eremothecium ashbyii and Ashbya gossypii, and bacteria, including Bacillus subtilis, Escherichia coli, and lactic acid bacteria, are ideal cell factories for riboflavin overproduction. Thus they are good candidates for enhancing the level of riboflavin in fermented foods or designing novel riboflavin bio-enriched foods with improved nutritional value and/or beneficial properties for human health. This review briefly describes the role of riboflavin in human health and the historical process of its industrial production, and then highlights riboflavin biosynthesis in bacteria and fungi, and finally summarizes the strategies for riboflavin overproduction based on both the optimization of fermentation conditions and the development of riboflavin-overproducing strains via chemical mutagenesis and metabolic engineering. Overall, this review provides an updated understanding of riboflavin biosynthesis and can promote the research and development of fermented food products rich in riboflavin.
Cronobacter species are a group of Gram-negative opportunistic pathogens, which cause meningitis, septicemia, and necrotizing enterocolitis in neonates and infants, with neurological sequelae in severe cases. Interest in Cronobacter has increased significantly in recent years due to its high virulence in children. In this review, we summarize the current understanding of the prevalence of Cronobacter species in several important food types. We discuss the response mechanisms enabling persistence in adverse growth conditions, as well as its pathogenicity. We emphasize the food safety concerns caused by Cronobacter and subsequent control methods, and clinical treatments.
The water sector needs to address viral-related public health issues, because water is a virus carrier, which not only spreads viruses (e.g., via drinking water), but also provides information about the circulation of viruses in the community (e.g., via sewage). It has been widely reported that waterborne viral pathogens are abundant, diverse, complex, and threatening the public health in both developed and developing countries. Meanwhile, there is great potential for viral monitoring that can indicate biosafety, treatment performance and community health. New developments in technology have been rising to meet the emerging challenges over the past decades. Under the current coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the world's attention is directed to the urgent need to tackle the most challenging public health issues related to waterborne viruses. Based on critical analysis of the water viral knowledge progresses and gaps, this article offers a roadmap for managing COVID-19 and other viruses in the water environments for ensuring public health.
Owing to the ongoing pandemic, the importance of and demand for antimicrobial textiles have reached new heights. In addition to being used for medical purposes, antimicrobial textiles could be a self-defense entity against microbes for the general population. Because textiles are widely used, they can effectively be used to prevent the spread of microbes worldwide. The conventional antibacterial finishing process of textiles is the wet treatment method using either the pad–dry–cure or exhaustion techniques. However, the textile wet treatment industries are major contributors to worldwide pollution, which is extremely concerning. Given the current and near-future high demand, it is imperative to include plasma in antimicrobial finishing to achieve high efficiency in production, while retaining a safe environment. Hence, this paper reviews the rationale of plasma use in textile antimicrobial finishing through a critical analysis of recent studies and emphasizes the types and mechanisms of plasma techniques available for application.
Soil microbial diversity is extremely vulnerable to fertilization, which is one of the main anthropogenic activities associated with global changes. Yet we know little about how and why soil microbial diversity responds to fertilization across contrasting local ecological contexts. This knowledge is fundamental for predicting changes in soil microbial diversity in response to ongoing global changes. We analyzed soils from ten 20-year field fertilization (organic and/or inorganic) experiments across China and found that the national-scale responses of soil bacterial diversity to fertilization are dependent on ecological context. In acidic soils from regions with high precipitation and soil fertility, inorganic fertilization can result in further acidification, resulting in negative impacts on soil bacterial diversity. In comparison, organic fertilization causes a smaller disturbance to soil bacterial diversity. Despite the overall role of environmental contexts in driving soil microbial diversity, a small group of bacterial taxa were found to respond to fertilization in a consistent way across contrasting regions throughout China. Taxa such as Nitrosospira and Nitrososphaera, which benefit from nitrogen fertilizer addition, as well as Chitinophagaceae, Bacilli, and phototrophic bacteria, which respond positively to organic fertilization, could be used as bioindicators for soil fertility in response to fertilization at the national scale. Overall, our work provides new insights into the importance of local environmental context in determining the responses of soil microbial diversity to fertilization, and identifies regions with acidic soils wherein soil microbial diversity is more vulnerable to fertilization at the national scale.
The decreasing cost of solar photovoltaics (PVs) and battery storage systems is driving their adoption in the residential distribution system, where more consumers are becoming prosumers. Accompanying this trend is the potential roll-out of home energy management systems (HEMSs), which provide a means for prosumers to respond to externalities such as energy price, weather, and energy demands. However, the economic operation of prosumers can affect grid security, especially when energy prices are extremely low or high. Therefore, it is paramount to design a framework that can accommodate the interests of the key stakeholders in distribution systems—namely, the network operator, prosumer, and aggregator. In this paper, a novel transactive energy (TE)-based operational framework is proposed. Under this framework, aggregators interact with the distribution grid operator through a negotiation process to ensure network security, while at the lower level, prosumers submit their schedule to the aggregator through the HEMS. If network security is at risk, aggregators will send an additional price component representing the cost of security (CoS) to the prosumer to stimulate further response. The simulation results show that the proposed framework can effectively ensure the economic operation of aggregators and prosumers in distribution systems while maintaining grid security.
Hospital projects worldwide often experience misperformance, showing a tendency to exceed their estimated cost, miss their deadline, suffer quality problems, and yield benefit shortfalls. Considering this ubiquitous problem, this paper aims to make sense of this phenomenon by addressing the following research question: How can we make sense of hospital project misperformance, and what can be done to mitigate its occurrence? We use an illustrative case study approach and the analytical lens of sense-making to examine the (mis)performance of three mega-hospital projects. Our research reveals issues such as scope changes, an inability to adapt and respond to risk and uncertainty, ineffectual project management and governance, and optimism bias, which combine to impact project performance adversely. We suggest that the two prominent theoretical perspectives dominating the literature in this field fall short of adequately explaining hospital project (mis)performance. We provide suggestions for improving the procu ement process of hospitals and submit there is a need to develop a robust and balanced theory of project (mis)performance.
Regular coronavirus disease 2019 (COVID-19) epidemic prevention and control have raised new requirements that necessitate operation-strategy innovation in urban rail transit. To alleviate increasingly serious congestion and further reduce the risk of cross-infection, a novel two-stage distributionally robust optimization (DRO) model is explicitly constructed, in which the probability distribution of stochastic scenarios is only partially known in advance. In the proposed model, the mean-conditional value-atrisk (mean-CVaR) criterion is employed to obtain a tradeoff between the expected number of waiting passengers and the risk of congestion on an urban rail transit line. The relationship between the proposed distributionally robust model and the traditional two-stage stochastic programming (SP) model is also depicted. Furthermore, to overcome the obstacle of model solvability resulting from imprecise probability distributions, a discrepancy-based ambiguity set is used to transform the robust counterpart into its computationally tractable form. A hybrid algorithm that combines a local search algorithm with a mixedinteger linear programming (MILP) solver is developed to improve the computational efficiency of largescale instances. Finally, a series of numerical examples with real-world operation data are executed to validate the proposed approaches.