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Highlights: Asymmetrically coordinated Co–N4–O sites on N-doped carbon nanofiber were prepared. Co–O coordination along the axial direction led to enhanced dielectric polarization loss. Multifunctional films were developed for practical application in harsh environments. Single-atom materials have demonstrated attractive physicochemical characteristics. However, understanding the relationships between the coordination environment of single atoms and their properties at the atomic level remains a considerable challenge. Herein, a facile water-assisted carbonization approach is developed to fabricate well-defined asymmetrically coordinated Co–N4–O sites on biomass-derived carbon nanofiber (Co–N4–O/NCF) for electromagnetic wave (EMW) absorption. In such nanofiber, one atomically dispersed Co site is coordinated with four N atoms in the graphene basal plane and one oxygen atom in the axial direction. In-depth experimental and theoretical studies reveal that the axial Co–O coordination breaks the charge distribution symmetry in the planar porphyrin-like Co–N4 structure, leading to significantly enhanced dielectric polarization loss relevant to the planar Co–N4 sites. Importantly, the film based on Co–N4–O/NCF exhibits light weight, flexibility, excellent mechanical properties, great thermal insulating feature, and excellent EMW absorption with a reflection loss of − 45.82 dB along with an effective absorption bandwidth of 4.8 GHz. The findings of this work offer insight into the relationships between the single-atom coordination environment and the dielectric performance, and the proposed strategy can be extended toward the engineering of asymmetrically coordinated single atoms for various applications. [ABSTRACT FROM AUTHOR]

Bacteria have developed antibiotic resistance during the large-scale use of antibiotics, and multidrug-resistant strains are common. The development of new antibiotics or antibiotic substitutes has become an important challenge for humankind. MPX is a 14 amino acid peptide belonging to the MP antimicrobial peptide family. In this study, the antibacterial spectrum of the antimicrobial peptide MPX was first tested. The antimicrobial peptide MPX was tested for antimicrobial activity against the gram-positive bacterium S. aureus ATCC 25923, the gram-negative bacteria E. coli ATCC 25922 and Salmonella enterica serovar Typhimurium CVCC541, and the fungus Candida albicans ATCC 90029. The results showed that MPX had good antibacterial activity against the above four strains, especially against E. coli, for which the MIC was as low as 15.625 μg/mL. The study on the bactericidal mechanism of the antimicrobial peptide revealed that MPX can destroy the integrity of the cell membrane, increase membrane permeability, and change the electromotive force of the membrane, thereby allowing the contents to leak out and mediating bacterial death. A mouse acute infection model was used to evaluate the therapeutic effect of MPX after acute infection of subcutaneous tissue by S. aureus. The study showed that MPX could promote tissue repair in S. aureus infection and alleviate lung damage caused by S. aureus. In addition, skin H&E staining showed that MPX treatment facilitated the formation of appropriate abscesses at the subcutaneous infection site and facilitated the clearance of bacteria by the skin immune system. The above results show that MPX has good antibacterial activity and broad-spectrum antibacterial potential and can effectively prevent the invasion of subcutaneous tissue by S. aureus, providing new ideas and directions for the immunotherapy of bacterial infections. [ABSTRACT FROM AUTHOR]

Aircraft icing is a fairly common phenomenon, which may occur during take-off, landing and flight of the aircraft. In order to ensure flight safety, it is necessary to carry out research on aircraft anti-icing technology. Here, we demonstrate a facile method to prepare icephobic coatings that can be applied to aircraft anti-icing systems by epoxy-silicone composite resin and polytetrafluoroethylene particles. Studies have shown that this icephobic coating not only has good superhydrophobicity, abrasion resistance and aging resistance, but also has excellent anti-icing function. Supercooled droplet impact and delayed icing test results show that the icephobic surface can completely repel supercooled (− 2 °C) water droplets at − 10 °C (rebound within ~ 12 ms), while delaying the freezing process for ~ 718 s. After 10 times of mechanical deicing, the coating still maintained a low ice adhesion strength (~ 112.4 kPa) and consistent wettability. In addition, the icing state of the developed coating was evaluated by used the icing wind tunnel to simulate the icing environment of the aircraft during natural flight, and the results showed that it can significantly reduce the thickness of ice accumulation. The above properties of this icephobic surface provide a new idea for aircraft anti-icing technology. [ABSTRACT FROM AUTHOR]

Exploring multi-target drugs (MTDs) is a prevalent method against Alzheimer's disease (AD). However, the current developed MTDs based on the "framework combination" technique or using flavonoids have not realized better healing effects owing to a complex metabolic process and low bioavailability. Here, we propose an alternative strategy to develop self-assembled nanoparticles (NPs) as MTDs using 9-fluorenylmethyloxycarbonyl-tryptophan (Fmoc-Trp), quercetin (Que), and Fe2+ as building blocks through coordination and electrostatic interaction to generate Fmoc-Trp-Fe2+-Que (FTFQ) NPs. Whether in cell or in vivo, FTFQ NPs exhibited considerable biocompatibility attributing to the inherent biological affinity of assembly units. By combining the advantages of assemble approach and nanostructures, the obtained FTFQ NPs greatly enhanced the bioavailability of Que and displayed synergistic therapeutic effects through reducing Aβ aggregation in direct/indirect means and eliminating the toxicity induced by ROS and Aβ oligomer/fibrils. Furthermore, FTFQ NPs could obviously restore the AD zebrafish's mobility and stimulus response ability. More importantly, developing self-assembly NPs as MTDs could be an efficient and general method to promote other novel MTDs by extending the assemble units to other drugs, peptides, and metal ions. Based on above benefits, these self-assembled NPs could be as potential MTDs and show great promising application in AD treatment. [ABSTRACT FROM AUTHOR]

Highlights: A general method was developed to fabricate a series of honeycomb-like N-doped nanocarbons (3D M–NxC) doped with metal single atoms (Mn, Fe, Co, Cu, or Ni) with a high yield. The intrinsic dielectric properties of 3D M–NxC were identified for the first time at the atomic-level, revealing that the introduction of metal single atoms greatly increases both conductive loss and polarization loss. 3D Mn–NC exhibited high-performance electromagnetic wave absorption at a low filler loading of 10 wt% outperforming most reported absorbers. Atomically dispersed metals on N-doped carbon supports (M–NxCs) have great potential applications in various fields. However, a precise understanding of the definitive relationship between the configuration of metal single atoms and the dielectric loss properties of M–NxCs at the atomic-level is still lacking. Herein, we report a general approach to synthesize a series of three-dimensional (3D) honeycomb-like M–NxC (M = Mn, Fe, Co, Cu, or Ni) containing metal single atoms. Experimental results indicate that 3D M–NxCs exhibit a greatly enhanced dielectric loss compared with that of the NC matrix. Theoretical calculations demonstrate that the density of states of the d orbitals near the Fermi level is significantly increased and additional electrical dipoles are induced due to the destruction of the symmetry of the local microstructure, which enhances conductive loss and dipolar polarization loss of 3D M–NxCs, respectively. Consequently, these 3D M–NxCs exhibit excellent electromagnetic wave absorption properties, outperforming the most commonly reported absorbers. This study systematically explains the mechanism of dielectric loss at the atomic level for the first time and is of significance to the rational design of high-efficiency electromagnetic wave absorbing materials containing metal single atoms. [ABSTRACT FROM AUTHOR]

Highlights: A general method was developed to fabricate a series of honeycomb-like N-doped nanocarbons (3D M–NxC) doped with metal single atoms (Mn, Fe, Co, Cu, or Ni) with a high yield. The intrinsic dielectric properties of 3D M–NxC were identified for the first time at the atomic-level, revealing that the introduction of metal single atoms greatly increases both conductive loss and polarization loss. 3D Mn–NC exhibited high-performance electromagnetic wave absorption at a low filler loading of 10 wt% outperforming most reported absorbers. Atomically dispersed metals on N-doped carbon supports (M–NxCs) have great potential applications in various fields. However, a precise understanding of the definitive relationship between the configuration of metal single atoms and the dielectric loss properties of M–NxCs at the atomic-level is still lacking. Herein, we report a general approach to synthesize a series of three-dimensional (3D) honeycomb-like M–NxC (M = Mn, Fe, Co, Cu, or Ni) containing metal single atoms. Experimental results indicate that 3D M–NxCs exhibit a greatly enhanced dielectric loss compared with that of the NC matrix. Theoretical calculations demonstrate that the density of states of the d orbitals near the Fermi level is significantly increased and additional electrical dipoles are induced due to the destruction of the symmetry of the local microstructure, which enhances conductive loss and dipolar polarization loss of 3D M–NxCs, respectively. Consequently, these 3D M–NxCs exhibit excellent electromagnetic wave absorption properties, outperforming the most commonly reported absorbers. This study systematically explains the mechanism of dielectric loss at the atomic level for the first time and is of significance to the rational design of high-efficiency electromagnetic wave absorbing materials containing metal single atoms. [ABSTRACT FROM AUTHOR]

Purpose: Diabetic nephropathy (DN) is one of the most serious complications of diabetes mellitus and one of the most important causes of end-stage renal disease, but its pathogenesis has not been elucidated so far, and there is no effective treatment. Methods: DN models of rats and MPC-5 cells were established with streptozotocin (STZ) and high glucose (HG) in vivo and in vitro, respectively. Cell markers desmin and nephrin in foot kidney tissue were detected by Western blot. CCNG1 level in vitro was analyzed by Western blot and immunohistochemistry. CCK-8 assay and flow cytometry were conducted to analyze the effect of CCNG1 on HG-treated MPC-5 cells. Apoptosis-related proteins (Bcl-2, Bax and p53), CCNG1, and MDM2 were determined by RT-qPCR and Western blot. Results: The level of nephrin was decreased, while desmin was increased in STZ-induced DN rats and CCNG1 level was also enhanced by STZ. In vitro experiments indicated that MPC-5 cell viability was inhibited and apoptosis was induced by HG and we also found that CCNG1 expression was up-regulated by HG and negatively correlated with MDM2 level. The effects of HG on MPC-5 cell viability, apoptosis, and cell cycle were reversed by silencing CCNG1, but further deteriorated by overexpression of CCNG1. Furthermore, overexpression of MDM2 inhibited HG-induced MPC-5 cell injury and CCNG1 expression. Conclusions: These findings revealed that down-regulation of CCNG1 has protection effects in DN that is mechanistically linked to MDM2-p53 pathways. [ABSTRACT FROM AUTHOR]

Salmonella is an important zoonotic pathogen and is a major cause of gastrointestinal diseases worldwide. The current serious problem of antibiotic abuse has prompted the search for new substitutes for antibiotics. JH-3 is a small antimicrobial peptide with broad-spectrum bactericidal activity. In this study, we showed that JH-3 has good bactericidal activity towards the clinical isolate Salmonella enterica serovar Typhimurium strain CVCC541. The minimum inhibitory concentration (MIC) of JH-3 against this bacterium was determined to be 100 μg/mL, which could decrease the number of CVCC541 cells by 1000-fold in vitro within 5 h. The transmission electron microscopy (TEM) results showed that JH-3 can damage the cell wall and membrane of CVCC541, leading to the leakage of cell contents and subsequent cell death. To measure the bactericidal activity of CVCC541-infected mice were treated intraperitoneally 40 or 10 mg/kg JH-3 at 2 h or 3 days postinfection. Our results showed that treatment with 40 mg/kg JH-3 at 2 h postinfection had the best therapeutic effect and could significantly protect mice from a lethal dose of CVCC541. Furthermore, the clinical symptoms, bacterial burden in blood and organs, and intestinal pathological changes were all decreased and were close to normal. This study examined the therapeutic effect of the antimicrobial peptide JH-3 against S. enterica CVCC541 infection for the first time and determined the therapeutic effect of different JH-3 doses and treatment times, laying the foundation for studies of new antimicrobial agents. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide even with low concentration in environment is very pernicious to the health, Therefore, the design of gas sensors for detecting H2S is highly desirable. In this work, porous spinel ZnCo2O4 nanosheets (NSs) were synthesized via a hydrothermal method and followed by the thermal treatment. Structural characterizations indicate that the porous NSs are composed of ~ 14 nm interconnected ZnCo2O4 nanoparticles. The porous spinel ZnCo2O4 NSs exhibit enhanced H2S sensing performance in comparison to Co3O4 NSs. The detection limit of the porous ZnCo2O4 NSs is down to 100 ppb H2S with a sensor response value of 1.32 even at relatively low operating temperature of 120 °C. Furthermore, the porous ZnCo2O4 NSs have fascinating selectivity and good long-term stability and relatively rapid response time. The gas sensing mechanism of the ZnCo2O4 NSs gas sensor is also discussed in terms of the effects of oxygen vacancies. In view of the exciting gas-sensing properties and facile preparation method, the porous ZnCo2O4 NSs are ideal candidates for the H2S sensors. [ABSTRACT FROM AUTHOR]

The atomizer with micro cone apertures has advantages of ultra-fine atomized droplets, low power consumption and low temperature rise. The current research of this kind of atomizer mainly focuses on the performance and its application while there is less research of the principle of the atomization. Under the analysis of the dispenser and its micro-tapered aperture's deformation, the volume changes during the deformation and vibration of the micro-tapered aperture on the dispenser are calculated by coordinate transformation. Based on the characters of the flow resistance in a cone aperture, it is found that the dynamic cone angle results from periodical changes of the volume of the micro-tapered aperture of the atomizer and this change drives one-way flows. Besides, an experimental atomization platform is established to measure the atomization rates with different resonance frequencies of the cone aperture atomizer. The atomization performances of cone aperture and straight aperture atomizers are also measured. The experimental results show the existence of the pumping effect of the dynamic tapered angle. This effect is usually observed in industries that require low dispersion and micro- and nanoscale grain sizes, such as during production of high-pressure nozzles and inhalation therapy. Strategies to minimize the pumping effect of the dynamic cone angle or improve future designs are important concerns. This research proposes that dynamic micro-tapered angle is an important cause of atomization of the atomizer with micro cone apertures. [ABSTRACT FROM AUTHOR]

This paper gives systematic study on the process of ice layer accretion, especially the mass and energy transfer between two-phase distribution (air and water droplet) and icing build-up region along the surface of airfoil. Based on the theory of momentum and thermal boundary layer, the governing equations are constituted by considering the conservation of mass and energy in each control volume which is equivalent to the grid cell in fact. The finite volume method is used to discrete the control equations and then the calculations for convective heat transfer coefficient and ice shape are accomplished successfully. During the icing computation, the heat transfer characteristics are updated timely after every time step using multi-time step algorithm. In order to verify reliability of this method mentioned above, some results are compared to the ones from LEWICE software and experiment. At last, the effects of several key parameters on heat transfer coefficient and ice shape are presented in this paper using the model of NACA 4412 airfoil, and these factors include free-stream velocity, static temperature, angle of attack and the roughness height of surface. [ABSTRACT FROM AUTHOR]

Porous FeO sub-micro particles with sphere-like, cube-like and walnut-like morphologies were obtained by a two-step process, and the electromagnetic properties of the FeO particle/wax composites were investigated. The reflect loss was less than −20 dB for all of the composites in different frequency ranges. The cube-like and walnut-like FeO composites exhibit improved complex permittivity and permeability and dual-frequency and wide bandwidth absorption characteristics, which is mainly attributed to the larger shape anisotropy. Such a high absorption property indicates that these porous FeO particles with various morphologies are very promising for electromagnetic wave absorptive materials. [ABSTRACT FROM AUTHOR]

Crystalline SnO2 nanoparticles (NPs) with a diameter less than 6 nm are synthesized using potassium stannate trihydrate as the precursor in a basic system. The synthesized NPs can detect ethanol at a ppm level even at 100°C. Furthermore, the NPs have good selectivity to ethanol. The excellent ethanol sensing performances are attributed to the small size effect according to the space-charge model. [ABSTRACT FROM AUTHOR]

CdS/α-Fe2O3 hierarchical nanostructures, where the CdS nanorods grow irregularly on the side surface of α-Fe2O3 nanorods, were synthesized via a three-step process. The diameters and lengths of CdS nanorods can be tuned by changing the ethylenediamine (EDA) and Cd ion concentrations. The magnetic investigations by superconducting quantum interference device indicate that the hierarchical nanostructures have an Morin transition at lower temperature (230 K) than that of the single bulk α-Fe2O3 materials (263 K). Importantly, the hierarchical nanostructures exhibit weakly ferromagnetic characteristics at 300 K. A sharp peak assigned to the surface trap induced emission are observed in room temperature PL spectra. Combining with the optoelectronic properties of CdS, the CdS/α-Fe2O3 hierarchical nanostructures may be used as multi-functional materials for optoelectronic and magnetic devices. [ABSTRACT FROM AUTHOR]

In this paper, the W18O49 nanospheres (W18O49 NSs) with diameter about 100 nm have been found to exhibit intrinsic peroxidase-like activity, which can catalytically oxidize 3,3′,5,5′-tetramethylbenzidine (TMB) by H2O2 to produce a color reaction. Different from the catalytic behavior of the Fe3O4 particles, the possible catalysis mechanism was notably dependent on the surface oxygen vacancies (SOVs) abundant in W18O49 NSs, which served as important catalytic sites. Moreover, due to the speciality with high surface area (136.13 m2 g−1) and negative potential (− 54.8 mV), the obtained W18O49 NSs could be used as efficient peroxidase mimetic to remove the dye pollutant methylene blue (MB) in the assistance of H2O2. And the degradation efficiency of MB could be achieved above 91% with 50 μg mL−1 W18O49 NSs.In this paper, the W18O49 nanospheres (W18O49 NSs) have been first found to exhibit intrinsic peroxidase-like activity. Different from the catalytic behavior of the Fe3O4 particles, the possible catalysis mechanism was notably dependent on the surface oxygen vacancies (SOVs) abundant in W18O49 NSs, which serve as important catalytic sites. [ABSTRACT FROM AUTHOR]