Optical characteristics of luminescent materials, including emission color (wavelength), lifetime, and excitation mode, play crucial roles in data communication and information security. Conventional ...luminescent materials generally display unicolor, unitemporal, and unimodal (occasionally bimodal) emission, resulting in low‐level readout and decoding. The development of multicolor, multitemporal, and multimodal luminescence in a single material has long been considered to be a significant challenge. In this study, for the first time, the superior integration of colorful (red–orange–yellow–green), bitemporal (fluorescent and delayed), and four‐modal (thermo‐/mechano‐motivated and upconverted/downshifted) emissions in a particular piezoelectric particle via optical multiplexing of dual‐lanthanide dopants is demonstrated. The as‐prepared versatile NaNbO3:Pr3+,Er3+ luminescent microparticles shown are particularly suitable for embedding into polymer films to achieve waterproof, flexible/wearable and highly stretchable features, and synchronously to provide multidimensional codes that can be visually read‐out using simple and commonly available tools (including the LED of a smartphone, pen writing, cooling–heating stimuli, and ultraviolet/near‐infrared lamps). These findings offer unique insight for designing highly integrated stimuli‐responsive luminophors and smart devices toward a wide variety of applications, particularly advanced anticounterfeiting technology.
Thermo‐mechano‐opto‐responsive bitemporal (fluorescent and delayed) colorful (red–orange–yellow–green) luminescence is designed and achieved through optical multiplexing of dual‐lanthanides of Pr3+ and Er3+ in NaNbO3 piezoelectric microparticles. The smart materials are well‐embedded into polymer elastomers to show waterproof, flexible/wearable and highly‐stretchable features, and provide multidimensional codes that enable visual readout using commonly available tools (e.g., smartphone flashlight, pen writing, and cooling‐heating stimuli).
Visually readable codes play a crucial role in anticounterfeiting measures. However, current coding approaches do not enable time‐dependent codes to be visually read, adjusted, and differentiated in ...bright and dark fields. Here, using a combined strategy of piezoelectric lattice selection, oxygen vacancy engineering, and activator doping, a lanthanide ion‐doped titanate is developed that integrates mechano‐, thermo‐, and photo‐responsive color change (>18 h for bright field), persistent luminescence (>6 h for dark field), and stimulus‐triggered multimodal luminescence. The feasibility of optical encoding, visual displaying, and stimulus‐responsive encrypting of time‐dependent, dual‐field information by using the developed material is demonstrated. In particular, the differentiated display of dual‐field modes is achieved by combining mechanostimulated abolition of only the persistent luminescence and thermo‐ and photostimulated reversal of both the color change and persistent luminescence. The results provide new insights for designing advanced materials and encryption technologies for photonic displays, information security, and intelligent anticounterfeiting.
The encoding, displaying, and encrypting of information in bright and dark fields are demonstrated via a newly designed versatile material that integrates bright‐field color change, dark‐field persistent luminescence, and stimuli‐responsive multiluminescence. Differential encryption of the dual‐field patterns is creatively modulated by combining the mechanostimulated loss of only the dark‐field patterns and thermo‐ and photostimulated dual abolition of the dual‐field patterns.
Organic nitrates are broadly applied as pharmaceuticals (acting as efficient nitric oxide donor), energetic materials, building blocks in organic synthesis, etc. However, practical and direct methods ...to access organic nitrates efficiently are still rare, mainly due to the lack of powerful nitrooxylating reagents. Herein, we report bench‐stable and highly reactive noncyclic hypervalent iodine nitrooxylating reagents, oxybis(aryl‐λ3‐iodanediyl) dinitrates (OAIDNs, 2), which are prepared just by using aryliodine diacetate and HNO3. The reagents are used to achieve a mild and operationally simple protocol to access diverse organic nitrates. By employing of 2, zinc‐catalyzed regioselective nitrooxylation of cyclopropyl silyl ethers is realized efficiently to access the corresponding β‐nitrooxy ketones with high functional‐group tolerance. Moreover, a series of direct and catalyst‐free nitrooxylations of enolizable C−H bonds are carried out smoothly to afford the desired organic nitrates within minutes by just mixing the substrates with 2 in dichloromethane.
A bench‐stable and highly reactive noncyclic hypervalent iodine nitrooxylating reagent is prepared from aryliodine diacetate and HNO3. This reagent facilitates the zinc‐catalyzed regioselective nitrooxylation of cyclopropyl silyl ethers with broad scope, and also can be used in the nitrooxylation of various enolizable C−H bonds.
The engineering of intermolecular interaction is challenging but critical for magnetically switchable molecules. Here, we prepared two cyanide‐bridged Fe4Co4 cube complexes via the alkynyl‐ and ...alcohol‐functionalized trispyrazoyl capping ligands. The alkynyl‐functionalized complex 1 exhibited a thermally‐induced incomplete metal‐to‐metal electron transfer (MMET) behaviour at around 220 K, while the mixed alkynyl/alcohol‐functionalized cube of 2 showed a complete and abrupt MMET behaviour at 232 K. Remarkably, both compounds showed a long‐lived photo‐induced metastable state up to 200 K. The crystallographic study demonstrated that the incomplete transition of 1 was likely due to the possible elastic frustration originating from the competition between the anion‐propagated elastic interactions and inter‐cluster alkynyl‐alkynyl & CH‐alkynyl interactions, whereas the latter are eliminated in 2 as a result of the partial substitution by the alcohol‐functionalized ligand. Additionally, the introduction of chemically distinguishable cobalt centers within the cube unit of 2 did not lead to a two‐step but a one‐step transition, possibly because of the strong ferroelastic intramolecular interaction through the cyanide bridges.
Two cyanide‐bridged Fe4Co4 cubes were prepared via a mixed‐ligand approach. The molecular origins of their distinct (incomplete vs. complete) metal‐to‐metal electron transfer (MMET) properties were identified as the presence and absence of the inter‐cluster alkynyl‐alkynyl and CH/π interactions. These compete with the cluster‐anion interactions, resulting in the underlying elastic frustration and stopping the complete spin transition in 1.
The fabrication of highly efficient and sustainable electrocatalysts used for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is exceedingly challenging and warranted for ...overall water splitting. In this work, we successfully synthesized a series of metal–organic frameworks (MOFs), namely, as Fe2M-MOF (M = Fe, Co, Ni, Zn, Mn; H4L = 3,3,5,5′-azoxybenzenetetracarboxylic acid) under a simple and mild condition, in which the Fe3 cluster as a basic building unit was replaced by the second kind of metal center; at the same time, a redox-active organic linker was adopted. The Fe2M-MOF system as a multifunctional catalyst realizes great improvement of the OER and HER performances. Among of them, the Fe2Co-MOF catalyst exhibits an extremely low overpotential of 339 mV at a current density of 10 mA cm–2 and a very small Tafel slope of 36.2 mV dec–1 in an alkaline electrolyte for OER. This result has far exceeded the commercial catalyst IrO2. Meanwhile, Fe2Zn-MOF manifests excellent HER activity with a small overpotential of 221 mV at 10 mA cm–2 and a low Tafel slope of 174 mV dec–1. In addition, the good long-term stability for these catalysts can be evaluated under working conditions. Systematic investigations are used to explain the enhanced electrocatalytic mechanism. In conclusion, we provide a simple and effective strategy for the preparation of multifunctional catalysts for energy conversion applications based on a pristine MOF material with redox-active metal centers and organic linkers.
There is an urgent need for animal models to study SARS-CoV-2 pathogenicity. Here, we generate and characterize a novel mouse-adapted SARS-CoV-2 strain, MASCp36, that causes severe respiratory ...symptoms, and mortality. Our model exhibits age- and gender-related mortality akin to severe COVID-19. Deep sequencing identified three amino acid substitutions, N501Y, Q493H, and K417N, at the receptor binding domain (RBD) of MASCp36, during in vivo passaging. All three RBD mutations significantly enhance binding affinity to its endogenous receptor, ACE2. Cryo-electron microscopy analysis of human ACE2 (hACE2), or mouse ACE2 (mACE2), in complex with the RBD of MASCp36, at 3.1 to 3.7 Å resolution, reveals the molecular basis for the receptor-binding switch. N501Y and Q493H enhance the binding affinity to hACE2, whereas triple mutations at N501Y/Q493H/K417N decrease affinity and reduce infectivity of MASCp36. Our study provides a platform for studying SARS-CoV-2 pathogenesis, and unveils the molecular mechanism for its rapid adaptation and evolution.
This study focuses on the additive manufacturing technique of selective laser melting (SLM) to produce Ti-6Al-4V-Zn titanium alloy. The addition of zinc at 0.3 wt.% was investigated to improve the ...strength and ductility of SLM Ti-6Al-4V alloys. The microstructure and mechanical properties were analyzed using different vacuum heat treatment processes, with the 800-4-FC specimen exhibiting the most favorable overall mechanical properties. Additionally, zinc serves as a stabilizing element for the β phase, enhancing the resistance to particle erosion and corrosion impedance of Ti-6Al-4V-Zn alloy. Furthermore, the incorporation of trace amounts of Zn imparts improved impact toughness and stabilized high-temperature tensile mechanical properties to SLM Ti-6Al-4V-Zn alloy. The data obtained serve as valuable references for the application of SLM-64Ti.
We study the mixed state entanglement in a holographic axion model. We find that the holographic entanglement entropy (HEE), mutual information (MI) and entanglement of purification (EoP) exhibit ...very distinct behaviors with system parameters. The HEE exhibits universal monotonic behavior with system parameters, while the behaviors of MI and EoP relate to the specific system parameters and configurations. We find that MI and EoP can characterize mixed state entanglement better than HEE since they are less affected by thermal effects. Specifically, the MI partly cancels out the thermal entropy contribution, while the holographic EoP is not dictated by the thermal entropy in any situation. Moreover, we argue that EoP is more suitable for describing mixed state entanglement than MI. Because the MI of large configurations are still dictated by the thermal entropy, while the EoP will never be controlled only by the thermal effects.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Recent proposals of topological flat band models have provided a new route to realize the fractional quantum Hall effect without Landau levels. We study hard-core bosons with short-range interactions ...in two representative topological flat band models, one of which is the well-known Haldane model (but with different parameters). We demonstrate that fractional quantum Hall states emerge with signatures of an even number of quasidegenerate ground states on a torus and a robust spectrum gap separating these states from the higher energy spectrum. We also establish quantum phase diagrams for the filling factor 1/2 and illustrate quantum phase transitions to other competing symmetry-breaking phases.
Rational design of a Prussian blue analogue (PBA)@Ni-Co layered double hydroxide (NiCo-LDH) nanocomposite electrode material is vitally important for synthesizing high-performance supercapacitor ...electrodes. In this work, such nanocomposite electrode materials were successfully fabricated by a facile hydrothermal method. Firstly, three-dimensional (3D) regulated NiCo-LDH nanosheets with high interlayer space were grown on nickel foam under mild synthetic conditions. Then these nanosheets as a precursor were
in situ
converted into the target PBA@NiCo-LDH/NF nanocomposite electrode by a facile thermal ion-exchange reaction with potassium ferricyanide (K
3
Fe(CN)
6
). A series of PBA@NiCo-LDH/NF nanocomposite electrodes were fabricated with different ratios of Ni and Co and reaction temperatures. Their structures and morphologies were characterized by X-ray diffraction (XRD), FT-IR and scanning electron microscopy (SEM). Electrochemical investigation reveals that the PBA@Ni
0.4
Co
0.6
-LDH electrode exhibits the best electrochemical performance with an area specific capacitance of 2004.26 mF cm
−2
at 1 mA cm
−2
, which is much higher (about three times) than the properties of each single component. All results demonstrate that (1) high-performance composite electrodes can be effectively fabricated and (2) fabrication of such composites is highly necessary and important.
A series of PBA@NiCo-LDH/NF samples have been successfully fabricated by a facile and
in situ
method, and they show exciting electrochemical performance as supercapacitor electrodes with an area specific capacitance of 2004.26 mF cm
−2
at 1 mA cm
−2
.
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