We pave the way for future gravitational-wave detection experiments, such as the big bang observer and DECIGO, to constraint dark sectors made of SU(N) Yang-Mills confined theories. We go beyond the ...state-of-the-art by combining first principle lattice results and effective field theory approaches to infer essential information about the nonperturbative dark deconfinement phase transition driving the generation of gravitational-waves in the early Universe, such as the order, duration and energy budget of the phase transition which are essential in establishing the strength of the resulting gravitational-wave signal.
To reduce information exchange requirements in smart grids, an event-triggered communication-based distributed optimization is proposed for economic dispatch. In this work, the θ-logarithmic ...barrier-based method is employed to reformulate the economic dispatch problem, and the consensus-based approach is considered for developing fully distributed technology-enabled algorithms. Specifically, a novel distributed algorithm utilizes the minimum connected dominating set (CDS), which efficiently allocates the task of balancing supply and demand for the entire power network at the beginning of economic dispatch. Further, an event-triggered communication-based method for the incremental cost of each generator is able to reach a consensus, coinciding with the global optimality of the objective function. In addition, a fast gradient-based distributed optimization method is also designed to accelerate the convergence rate of the event-triggered distributed optimization. Simulations based on the IEEE 57-bus test system demonstrate the effectiveness and good performance of proposed algorithms.
Herein we present a new viologen‐based radical‐containing metal–organic framework (RMOF) Gd‐IHEP‐7, which upon heating in air undergoes a single‐crystal‐to‐single‐crystal transformation to generate ...Gd‐IHEP‐8. Both RMOFs exhibit excellent air and water stability as a result of favorable radical‐radical interactions, and their long‐lifetime radicals result in wide spectral absorption in the range 200–2500 nm. Gd‐IHEP‐7 and Gd‐IHEP‐8 show excellent activity toward solar‐driven nitrogen fixation, with ammonia production rates of 128 and 220 μmol h−1 g−1, respectively. Experiments and theoretical calculations indicate that both RMOFs have similar nitrogen fixation pathways. The enhanced catalytic efficiency of Gd‐IHEP‐8 versus Gd‐IHEP‐7 is attributed to intermediates stabilized by enhanced hydrogen bonding.
A single‐crystal‐to‐single‐crystal (SCSC) transformation of stable radical‐containing MOF Gd‐IHEP‐7 generates Gd‐IHEP‐8. It is accompanied by a marked increase in efficiency of sacrificial agent‐free photocatalytic nitrogen fixation to yield NH3 from H2O and N2 under simulated solar light irradiation at ambient temperature. The NH3 production rate of 220 μmol h−1 g−1 for Gd‐IHEP‐8 is a new record for MOF photocatalysts.
A pandemic of severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2) infection broke out all over the world; however, epidemiological data and viral shedding in pediatric patients are limited. ...We conducted a retrospective, multicenter study, and followed‐up with all children from the families with SARS‐CoV‐2 infected members in Zhejiang Province, China. All infections were confirmed by testing the SARS‐CoV‐2 RNA with real‐time reverse transcription PCR method, and epidemiological data between children and adults in the same families were compared. Effect of antiviral therapy was evaluated observationally and fecal‐viral excretion times among groups with different antiviral regiments were compared with Kaplan‐Meier plot. By 29 February 2020, 1298 cases from 883 families were confirmed with SARS‐CoV‐2 infection and 314 of which were families with children. Incidence of infection in child close contacts was significantly lower than that in adult contacts (13.2% vs 21.2%). The mean age of 43 pediatric cases was 8.2 years and mean incubation period was 9.1 days. Forty (93.0%) were family clustering. Thirty‐three children had coronavirus disease 2019 (20 pneumonia) with mild symptoms and 10 were asymptomatic. Fecal SARS‐CoV‐2 RNA detection was positive in 91.4% (32/35) cases and some children had viral excretion time over 70 days. Viral clearance time was not different among the groups treated with different antiviral regiments. No subsequent infection was observed in family contacts of fecal‐viral‐excreting children. Children have lower susceptibility of SARS‐CoV‐2 infection, longer incubation, and fecal‐viral excretion time. Positive results of fecal SARS‐CoV‐2 RNA detection were not used as indication for hospitalization or quarantine.
Highlights
Children had lower susceptibility for SARS‐CoV‐2 infection than adults.
Children had longer incubation period and fecal viral excretion time after infected by SARS‐CoV‐2.
Viral clearance time was not different among the groups treated with different antiviral regiments.
Children had milder clinical symptoms, better clinical outcome, and more common fecal viral excretion.
Positive results of fecal SARS‐CoV‐2 RNA detection are not used as indication for hospitalization or quarantine.
Attribute reduction is one of the biggest challenges encountered in computational intelligence, data mining, pattern recognition, and machine learning. Effective in feature selection as the rough set ...theory is, it can only handle symbolic attributes. In order to overcome this drawback, the fuzzy rough set model is proposed, which is an extended model of rough sets and is able to deal with imprecision and uncertainty in both symbolic and numerical attributes. The existing attribute selection algorithms based on the fuzzy rough set model mainly take the angle of "attribute set," which means they define the object function representing the predictive ability for an attribute subset with regard to the domain of discourse, rather than following the view of an "object pair." Algorithms from the viewpoint of the object pair can ignore the object pairs that are already discerned by the selected attribute subsets and, thus, need only to deal with part of object pairs instead of the whole object pairs from the discourse, which makes such algorithms more efficient in attribute selection. In this paper, we propose the concept of reduced maximal discernibility pairs, which directly adopts the perspective of the object pair in the framework of the fuzzy rough set model. Then, we develop two attribute selection algorithms, named as reduced maximal discernibility pairs selection and weighted reduced maximal discernibility pair selection, based on the reduced maximal discernibility pairs. Experiment results show that the proposed algorithms are effective and efficient in attribute selection.
Elastic metal–organic materials (MOMs) capable of multiple stimuli‐responsiveness based on dual‐stress and thermally responsive triple‐helix coordination polymers are presented. The strong ...metal‐coordination linkage and the flexibility of organic linkers in these MOMs, rather than the 4 Å stacking interactions observed in organic crystals, causes the helical chain to act like a molecular spring and thus accounts for their macroscopic elasticity. The thermosalient effect of elastic MOMs is reported for the first time. Crystal structure analyses at different temperatures reveal that this thermoresponsiveness is achieved by adaptive regulation of the triple‐helix chains by fine‐tuning the opening angle of flexible V‐shaped organic linkers and rotation of its lateral conjugated groups to resist possible expansion, thus demonstrating the vital role of adaptive reorganization of triple‐helix metal–organic chains as a molecular spring‐like motif in crystal jumping.
Dual‐stress and thermally responsive crystalline metal–organic materials (MOMs) based on molecular spring‐like triple‐helix coordination polymers are presented. As the first example of thermosalient effect in elastic MOMs, these compounds undergo elastic flexure upon external stress as well as cracking and jumping after thermal treatment.
Uranyl–organic frameworks (UOFs) have recently been the object of many research endeavors due to the unique coordination mode of uranyl ions and their attractive physicochemical properties. Here, a ...new (3,4)‐connected UOF (U‐IHEP‐4) assembled from uranyl and porphyrin ligand tetrakis(4‐carboxyphenyl)porphyrin (H4TCPP) is reported, which represents the first case of actinide porphyrinic MOFs. Adsorption experiments in DMF solution demonstrated that U‐IHEP‐4 selectively adsorbs positively charged dyes, which is in line with its negatively charged framework and large pore volume ratio (90 %). Remarkably, U‐IHEP‐4 exhibited high catalytic activity for the dehydrogenation of N‐heterocycles to synthesize the corresponding aromatic heterocycles and it can be used as an efficient heterogeneous catalyst.
A new uranyl–organic framework (U‐IHEP‐4) based on porphyrin derivative ligand was synthesized, filling the gap of porphyrinic MOFs in the field of actinide chemistry. The compound U‐IHEP‐4 was demonstrated to be a heterogeneous catalyst for dehydrogenation of N‐heterocycles.
Promoting light absorption range of photocatalysts is of great significance to improve solar light‐driven photocatalytic CO2 reduction efficiency. Herein, a new viologen‐based multicomponent ...heterotrimetallic metal–organic framework (MOF) Cu3Th6(µ3‐O)4(µ3‐OH)4(cpb)12FeIII(CN)66 (IHEP‐14) with an unprecedented (6, 18)‐connected she‐d topology is presented. Upon UV irradiation, this MOF undergoes ligand and iron photoreduction, and a single‐crystal‐to‐single‐crystal transformation to generate persistent radical‐containing MOF Cu3Th6(µ3‐O)4(µ3‐OH)4(cpb•)12FeII(CN)66 (IHEP‐15). This radical‐containing MOF shows excellent stability without fading after at least 2 months in air. Besides extending the photoabsorption to a wider wavelength range covering from 200 to 2,500 nm, the generation of persistent radical in IHEP‐15 also largely enhances its CO2 adsorption capacity by a factor of three due to the strong affinity between π orbital of the radical and the π system of CO2. These attributes endow IHEP‐15 with excellent visible/NIR light‐driven CO2 photoreduction activity, with CO production rates under visible and NIR irradiation of 570.3 and 209.3 µmol h−1 g−1, respectively. Notably, the latter is a record high for NIR‐induced CO production among all MOFs reported so far.
A single‐crystal‐to‐single‐crystal (SCSC) transformation of unprecedented (6, 18)‐connected multicomponent MOF IHEP‐14 generates persistent radical‐containing MOF IHEP‐15, accompanied by a marked increase in CO2 sorption and visible/NIR photocatalytic reduction of CO2 to CO with high selectivity. The NIR light‐driven CO production rate of 209.3 µmol h−1 g−1 for IHEP‐15 is recorded high for NIR‐induced CO production among all MOFs reported so far.
The separation and recovery of uranium from radioactive wastewater is important from the standpoints of environmental protection and uranium reuse. In the present work, magnetically collectable ...TiO2/Fe3O4 and its graphene composites were fabricated and utilized for the photocatalytical removal of U(VI) from aqueous solutions. It was found that, under ultraviolet (UV) irradiation, the photoreactivity of TiO2/Fe3O4 for the reduction of U(VI) was 19.3 times higher than that of pure TiO2, which is strongly correlated with the Fe0 and additional Fe(II) generated from the reduction of Fe3O4 by TiO2 photoelectrons. The effects of initial uranium concentration, solution pH, ionic strength, the composition of wastewater, and organic pollutants on the U(VI) removal by TiO2/Fe3O4 were systematically investigated. The results demonstrated its excellent performance in the cleanup of uranium contamination. As graphene can efficiently attract the TiO2 photoelectrons and thus decrease their transfer to Fe3O4, the photodissolution of Fe3O4 in the TiO2/graphene/Fe3O4 composite can be largely alleviated compared to that of the TiO2/Fe3O4, rendering this ternary composite a much higher stability. In addition, scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray absorption near edge spectroscopy (XANES), and X-ray photoelectron spectroscopy (XPS) were used to explore the reaction mechanisms.
Delayed impulsive controllers are proposed in this paper to enable the agents in a class of second-order multiagent systems (MASs) to achieve state consensus, based, respectively, on the relative ...full-state and partial-state sampled-data measurements among neighboring agents. It is a challenging task to analyze the consensus behaviors of the considered MASs as the dynamics of such MASs will be subjected to joint effects from delay-dependent impulses, aperiodic sampling, and switchings among different communication graphs. A novel analytical approach, based upon the discretization method, state augmentation, and linear state transformation, is developed to establish the sufficient consensus criteria on the range of the impulsive intervals and the control parameters. Remarkably, it is found that consensus in the closed-loop MASs can be always ensured by skillfully selecting the control parameters as long as the nonuniform delays and the impulsive intervals are bounded. A numerical example is finally performed to validate the effectiveness of the proposed delayed impulsive controllers.
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