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A facile two‐step solution‐phase method has been developed for the preparation of hierarchical α‐MnO2 nanowires@Ni1‐xMnxOy nanoflakes core–shell nanostructures. Ultralong α‐MnO2 nanowires were synthesized by a hydrothermal method in the first step. Subsequently, Ni1‐xMnxOy nanoflakes were grown on α‐MnO2 nanowires to form core–shell nanostructures using chemical bath deposition followed by thermal annealing. Both solution‐phase methods can be easily scaled up for mass production. We have evaluated their application in supercapacitors. The ultralong one‐dimensional (1D) α‐MnO2 nanowires in hierarchical core–shell nanostructures offer a stable and efficient backbone for charge transport; while the two‐dimensional (2D) Ni1‐xMnxOy nanoflakes on α‐MnO2 nanowires provide high accessible surface to ions in the electrolyte. These beneficial features enable the electrode with high capacitance and reliable stability. The capacitance of the core–shell α‐MnO2@Ni1‐xMnxOy nanostructures (x = 0.75) is as high as 657 F g?1 at a current density of 250 mA g?1, and stable charging‐discharging cycling over 1000 times at a current density of 2000 mA g?1 has been realized.  相似文献   

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Interleukin 1 beta (IL‐1β)‐dependent inflammatory disorders, such as rheumatoid arthritis and psoriasis, pose a serious medical burden worldwide, where patients face a lifetime of illness and treatment. Organogold compounds have been used since the 1930s to treat rheumatic and other IL‐1β‐dependent diseases and, though their mechanisms of action are still unclear, there is evidence that gold interferes with the transmission of inflammatory signalling. Here we show for the first time that citrate‐stabilized gold nanoparticles, in a size dependent manner, specifically downregulate cellular responses induced by IL‐1β both in vitro and in vivo. Our results indicate that the anti‐inflammatory activity of gold nanoparticles is associated with an extracellular interaction with IL‐1β, thus opening potentially novel options for further therapeutic applications.  相似文献   

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Attachment of Li+ ion on graphene surface to realize Li+‐ion conductor is a real challenge because of the weak interaction between the ions and the functional groups of graphene oxide; although, a large number of theoretical results are already available in the literature. To overcome this problem, graphene oxide is functionalized by 1‐aza‐15‐crown‐5, the cage‐like structure containing four oxygens that can bind Li+ ion through electrostatic interaction. Li+ migration on graphene surface has been investigated using ac relaxation mechanism. Perfect Debye‐type relaxation behavior with β (relaxation exponent) value ≈1 resulting from single ion is observed. The activation energy of Li+ migration arising due to cation‐π interaction is found to be 0.37 eV, which agrees well with recently reported theoretical value. It is believed that this study will help to design isolated ion conductors for Li+‐ion battery.  相似文献   

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Rechargeable Zn/MnO2 batteries using mild aqueous electrolytes are attracting extensive attention due to their low cost, high safety, and environmental friendliness. However, the charge‐storage mechanism involved remains a topic of controversy so far. Also, the practical energy density and cycling stability are still major issues for their applications. Herein, a free‐standing α‐MnO2 cathode for aqueous zinc‐ion batteries (ZIBs) is directly constructed with ultralong nanowires, leading to a rather high energy density of 384 mWh g?1 for the entire electrode. Greatly, the H+/Zn2+ coinsertion mechanism of α‐MnO2 cathode for aqueous ZIBs is confirmed by a combined analysis of in situ X‐ray diffractometry, ex situ transmission electron microscopy, and electrochemical methods. More interestingly, the Zn2+‐insertion is found to be less reversible than H+‐insertion in view of the dramatic capacity fading occurring in the Zn2+‐insertion step, which is further evidenced by the discovery of an irreversible ZnMn2O4 layer at the surface of α‐MnO2. Hence, the H+‐insertion process actually plays a crucial role in maintaining the cycling performance of the aqueous Zn/α‐MnO2 battery. This work is believed to provide an insight into the charge‐storage mechanism of α‐MnO2 in aqueous systems and paves the way for designing aqueous ZIBs with high energy density and long‐term cycling ability.  相似文献   

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The hydrogen and carbon monoxide separation is an important step in the hydrogen production process. If H2 can be selectively removed from the product side during hydrogen production in membrane reactors, then it would be possible to achieve complete CO conversion in a single‐step under high temperature conditions. In the present work, the multilayer amorphous‐Si‐B‐C‐N/γ‐Al2O3/α‐Al2O3 membranes with gradient porosity have been realized and assessed with respect to the thermal stability, geometry of pore space and H2/CO permeance. The α‐Al2O3 support has a bimodal pore‐size distribution of about 0.64 and 0.045 µm being macroporous and the intermediate γ‐Al2O3 layer—deposited from boehmite colloidal dispersion—has an average pore‐size of 8 nm being mesoporous. The results obtained by the N2‐adsorption method indicate a decrease in the volume of micropores—0.35 vs. 0.75 cm3 g?1—and a smaller pore size ?6.8 vs. 7.4 Å—in membranes with the intermediate mesoporous γ‐Al2O3 layer if compared to those without. The three times Si‐B‐C‐N coated multilayer membranes show higher H2/CO permselectivities of about 10.5 and the H2 permeance of about 1.05 × 10?8 mol m?2 s?1 Pa?1. If compared to the state of the art of microporous membranes, the multilayer Si‐B‐C‐N/γ‐Al2O3/α‐Al2O3 membranes are appeared to be interesting candidates for hydrogen separation because of their tunable nature and high‐temperature and high‐pressure stability.  相似文献   

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In this paper, we investigate the economic‐statistical design method for the 2‐of‐2 runs rule and the 2‐of‐3 runs rule. The Markov chain approach is used to obtain the average run length and the process cycle time. In addition, a simplified algorithm is presented to search the optimal setting of the design parameters. A numerical example and sensitivity analysis are also provided to compare the performances of the runs rules. The results show that the use of runs rule scheme can reduce operating cost comparing with the Shewhart control chart while maintaining a good statistical performance. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

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The self‐assembly of human islet amyloid polypeptide (hIAPP) into β‐sheet‐rich nanofibrils is associated with the pathogeny of type 2 diabetes. Soluble hIAPP is intrinsically disordered with N‐terminal residues 8–17 as α‐helices. To understand the contribution of the N‐terminal helix to the aggregation of full‐length hIAPP, here the oligomerization dynamics of the hIAPP fragment 8–20 (hIAPP8‐20) are investigated with combined computational and experimental approaches. hIAPP8‐20 forms cross‐β nanofibrils in silico from isolated helical monomers via the helical oligomers and α‐helices to β‐sheets transition, as confirmed by transmission electron microscopy, atomic force microscopy, circular dichroism spectroscopy, Fourier transform infrared spectroscopy, and reversed‐phase high performance liquid chromatography. The computational results also suggest that the critical nucleus of aggregation corresponds to hexamers, consistent with a recent mass‐spectroscopy study of hIAPP8‐20 aggregation. hIAPP8‐20 oligomers smaller than hexamers are helical and unstable, while the α‐to‐β transition starts from the hexamers. Converted β‐sheet‐rich oligomers first form β‐barrel structures as intermediates before aggregating into cross‐β nanofibrils. This study uncovers a complete picture of hIAPP8‐20 peptide oligomerization, aggregation nucleation via conformational conversion, formation of β‐barrel intermediates, and assembly of cross‐β protofibrils, thereby shedding light on the aggregation of full‐length hIAPP, a hallmark of pancreatic beta‐cell degeneration.  相似文献   

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In this article an attempt is made to simplify the application of EC 6 by a strict and clear division of the EC 6 into calculation, execution and materials. The calculation engineer does not, therefore, need to get involved with building materials specific parameters, which make it much more difficult to get a view over the variety of possible combinations. The introduction of classes in the characteristics that are relevant for building materials means that the structural engineer specifies suitable quantities necessary for his task, the builder/product manufacturer by suitable methods and choice of unit/mortar combinations achieves the required classes and, the product manufacturer, in particular, should be entitled to have the possibility of the individual specification, e. g. as part of general appraisal certificates.  相似文献   

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Crystal phases play a key role in determining the physicochemical properties of a material. To date, many phases of transition metal dichalcogenides have been discovered, such as octahedral (1T), distorted octahedral (1T′), and trigonal prismatic (2H) phases. Among these, the 1T′ phase offers unique properties and advantages in various applications. Moreover, the 1T′ phase consists of unique zigzag chains of the transition metals, giving rise to interesting in‐plane anisotropic properties. Herein, the in‐plane optical and electrical anisotropies of metastable 1T′‐MoS2 layers are investigated by the angle‐resolved Raman spectroscopy and electrical measurements, respectively. The deconvolution of J1 and J2 peaks in the angle‐resolved Raman spectra is a key characteristic of high‐quality 1T′‐MoS2 crystal. Moreover, it is found that its electrocatalytic performance may be affected by the crystal orientation of anisotropic material due to the anisotropic charge transport.  相似文献   

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Fabrication of hierarchical nanosheet arrays of 1T phase of transition‐metal dichalcogenides is indeed a critical task, but it holds immense potential for energy storage. A single‐step strategy is employed for the fabrication of stable 1T‐MnxMo1–xS2–ySey and MoFe2S4–zSez hierarchical nanosheet arrays on carbon cloth as positive and negative electrodes, respectively. The flexible asymmetric supercapacitor constructed with these two electrodes exhibits an excellent electrochemical performance (energy density of ≈69 Wh kg?1 at a power density of 0.985 kW kg?1) with ultralong cyclic stability of ≈83.5% capacity retention, after 10 000 consecutive cycles. Co‐doping of the metal and nonmetal boosts the charge storage ability of the transition‐metal chalcogenides following enrichment in the metallic 1T phase, improvement in the surface area, and expansion in the interlayer spacing in tandem, which is the key focus of the present study. This study explicitly demonstrates the exponential enhancement of specific capacity of MoS2 following intercalation and doping of Mn and Se, and Fe2S3 following doping of Mo and Se could be an ideal direction for the fabrication of novel energy‐storage materials with high‐energy storage ability.  相似文献   

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Developing microwave absorption materials with ultrawide bandwidth and low density still remains a challenge, which restricts their actual application in electromagnetic signal anticontamination and defense stealth technology. Here a series of olive‐like γ‐Fe2O3@C core–shell spindles with different shell thickness and γ‐Fe2O3@C@α‐MnO2 spindles with different volumes of dipolar‐distribution cavities were successfully prepared. Both series of absorbers exhibit excellent absorption properties. The γ‐Fe2O3@C@α‐MnO2 spindle with controllable cavity volume exhibits an effective absorption (2O3@C spindle reaches as high as ?45 dB because of the optimized electromagnetic impedance balance between polymer shell and γ‐Fe2O3 core. Intrinsic ferromagnetism of the anisotropy spindle is confirmed by electron holography. Strong coupling of magnetic flux stray lines between spindles is directly imaged. This unique morphology and facile etching technique might facilitate the study of core–shell type microwave absorbers.  相似文献   

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