The authors provide at a look at the biological applications of supramolecular assemblies that have been designed for excitation energy transfer. The topics discussed include biosensors and ...bioimaging.
Exploring of new catalyst activation principle holds a key to unlock catalytic powers of cheap and earth‐abundant materials for large‐scale applications. In this regard, the vacancy defects have been ...proven to be effective to initiate catalytic active sites and endow high electrocatalytic activities. However, such electrocatalytically active defects reported to date have been mostly formed by anion vacancies. Herein, it is demonstrated for the first time that iron cation vacancies induce superb water splitting bifunctionality in alkaline media. A simple wet‐chemistry method is developed to grow ultrathin feroxyhyte (δ‐FeOOH) nanosheets with rich Fe vacancies on Ni foam substrate. The theoretical and experimental results confirm that, in contrast to anion vacancies, the formation of rich second neighboring Fe to Fe vacancies in δ‐FeOOH nanosheets can create catalytic active centers for both hydrogen and oxygen evolution reactions. The atomic level insight into the new catalyst activation principle based on metal vacancies is adaptable for developing other transition metal electrocatalysts, including Fe‐based ones.
Ultrathin feroxyhyte (δ‐FeOOH) nanosheets with rich Fe‐vacancies on Ni foam are synthesized, based on which an iron‐vacancy‐based catalyst activation principle to induce water‐splitting bifunctionality is proposed. Theoretical studies confirm that the formation of the second neighboring Fe to Fe vacancies in δ‐FeOOH nanosheets can create active centers for both hydrogen and oxygen evolution reactions.
We explored whether medical health workers had more psychosocial problems than nonmedical health workers during the COVID-19 outbreak.
An online survey was run from February 19 to March 6, 2020; a ...total of 2,182 Chinese subjects participated. Mental health variables were assessed via the Insomnia Severity Index (ISI), the Symptom Check List-revised (SCL-90-R), and the Patient Health Questionnaire-4 (PHQ-4), which included a 2-item anxiety scale and a 2-item depression scale (PHQ-2).
Compared with nonmedical health workers (n = 1,255), medical health workers (n = 927) had a higher prevalence of insomnia (38.4 vs. 30.5%, p < 0.01), anxiety (13.0 vs. 8.5%, p < 0.01), depression (12.2 vs. 9.5%; p< 0.04), somatization (1.6 vs. 0.4%; p < 0.01), and obsessive-compulsive symptoms (5.3 vs. 2.2%; p < 0.01). They also had higher total scores of ISI, GAD-2, PHQ-2, and SCL-90-R obsessive-compulsive symptoms (p ≤ 0.01). Among medical health workers, having organic disease was an independent factor for insomnia, anxiety, depression, somatization, and obsessive-compulsive symptoms (p < 0.05 or 0.01). Living in rural areas, being female, and being at risk of contact with COVID-19 patients were the most common risk factors for insomnia, anxiety, obsessive-compulsive symptoms, and depression (p < 0.01 or 0.05). Among nonmedical health workers, having organic disease was a risk factor for insomnia, depression, and obsessive-compulsive symptoms (p < 0.01 or 0.05).
During the COVID-19 outbreak, medical health workers had psychosocial problems and risk factors for developing them. They were in need of attention and recovery programs.
Development of stimuli‐responsive materials with complex practical functions is significant for achieving bioinspired artificial intelligence. It is challenging to fabricate stimuli‐responsive ...hydrogels showing simultaneous changes in fluorescence color, brightness, and shape in response to a single stimulus. Herein, a bilayer hydrogel strategy is designed by utilizing an aggregation‐induced emission luminogen, tetra‐(4‐pyridylphenyl)ethylene (TPE‐4Py), to fabricate hydrogels with the above capabilities. Bilayer hydrogel actuators with the ionomer of poly(acrylamide‐r‐sodium 4‐styrenesulfonate) (PAS) as a matrix of both active and passive layers and TPE‐4Py as the core function element in the active layer are prepared. At acidic pH, the protonation of TPE‐4Py leads to fluorescence color and brightness changes of the actuators and the electrostatic interactions between the protonated TPE‐4Py and benzenesulfonate groups of the PAS chains in the active layer cause the actuators to deform. The proposed TPE‐4Py/PAS‐based bilayer hydrogel actuators with such responsiveness to stimulus provide insights in the design of intelligent systems and are highly attractive material candidates in the fields of 3D/4D printing, soft robots, and smart wearable devices.
Bioinspired hydrogels with abilities of simultaneous fluorescence color and brightness changes, as well as complex shape deformation under pH stimulus by utilizing aggregation‐induced emission luminogens (AIEgens) and the bilayer hydrogel technique are designed and fabricated.
Nonlinear optical microscopy has become a powerful tool in bioimaging research due to its unique capabilities of deep optical sectioning, high‐spatial‐resolution imaging, and 3D reconstruction of ...biological specimens. Developing organic fluorescent probes with strong nonlinear optical effects, in particular third‐harmonic generation (THG), is promising for exploiting nonlinear microscopic imaging for biomedical applications. Herein, a simple method for preparing organic nanocrystals based on an aggregation‐induced emission (AIE) luminogen (DCCN) with bright near‐infrared emission is successfully demonstrated. Aggregation‐induced nonlinear optical effects, including two‐photon fluorescence (2PF), three‐photon fluorescence (3PF), and THG, of DCCN are observed in nanoparticles, especially for crystalline nanoparticles. The nanocrystals of DCCN are successfully applied for 2PF microscopy at 1040 nm NIR‐II excitation and THG microscopy at 1560 nm NIR‐II excitation, respectively, to reconstruct the 3D vasculature of the mouse cerebral vasculature. Impressively, the THG microscopy provides much higher spatial resolution and brightness than the 2PF microscopy and can visualize small vessels with diameters of ≈2.7 µm at the deepest depth of 800 µm in a mouse brain. Thus, this is expected to inspire new insights into the development of advanced AIE materials with multiple nonlinearity, in particular THG, for multimodal nonlinear optical microscopy.
Aggregation‐induced nonlinear optical effects, in particular third‐harmonic generation, of an aggregation‐induced emission luminogen (AIEgen) are observed in nanoparticles, especially for crystalline nanoparticles. AIEgen nanocrystals enable ultradeep intravital third‐harmonic generation imaging (up to 800 µm) of mouse cerebral vasculature with high spatial resolution (≈2.7 µm) at the deepest depth of 800 µm, much superior to two‐ and three‐photon fluorescence imaging.
Novel 3D Ni1−xCoxSe2 mesoporous nanosheet networks with tunable stoichiometry are successfully synthesized on Ni foam (Ni1−xCoxSe2 MNSN/NF with x ranging from 0 to 0.35). The collective effects of ...special morphological design and electronic structure engineering enable the integrated electrocatalyst to have very high activity for hydrogen evolution reaction (HER) and excellent stability in a wide pH range. Ni0.89Co0.11Se2 MNSN/NF is revealed to exhibit an overpotential (η10) of 85 mV at −10 mA cm−2 in alkaline medium (pH 14) and η10 of 52 mV in acidic solution (pH 0), which are the best among all selenide‐based electrocatalysts reported thus far. In particular, it is shown for the first time that the catalyst can work efficiently in neutral solution (pH 7) with a record η10 of 82 mV for all noble metal‐free electrocatalysts ever reported. Based on theoretical calculations, it is further verified that the advanced all‐pH HER activity of Ni0.89Co0.11Se2 is originated from the enhanced adsorption of both H+ and H2O induced by the substitutional doping of cobalt at an optimal level. It is believed that the present work provides a valuable route for the design and synthesis of inexpensive and efficient all‐pH HER electrocatalysts.
An integrated electrocatalyst comprising 3D mesoporous Ni0.89Co0.11Se2 nanosheet networks on Ni foam is synthesized, and it demonstrates very high activities and excellent stabilities for hydrogen evolution reaction (HER) in all‐pH conditions. Theoretical calculations verify that electronic structure engineering by optimal Co doping enhances the adsorption of H+ and H2O, leading to the advanced all‐pH HER activity of the catalyst.
The dynamic behavior of a macroscopic adhered hydrogel stabilized through controllable dynamic covalent interactions is reported. These interactions, involving the cross‐linked formation of a ...hydrogel through reaction of a diacylhydrazine precursor with a tetraformyl partner, increase as a function of time. By using a contact time of 24 h and different compounds with recognized aggregation‐induced emission features (AIEgens), it proves possible to create six laminated acylhydrazone hydrogels displaying different fluorescent colors. Blocks of these hydrogels are then adhered into a structure resembling a Rubik's Cube, a trademark of Rubik's Brand Limited, (RC) and allowed to anneal for 1 h. This produces a 3 × 3 × 3 block (RC) wherein the individual fluorescent gel blocks are loosely adhered to one another. As a consequence, the 1 × 3 × 3 layers making up the RC can be rotated either horizontally or vertically to produce new patterns. Ex situ modification of the RC or application of a chemical stimulus can be used to produce new color arrangements. The present RC structure highlights how the temporal features, strong versus weak adhesion, may be exploited to create smart macroscopic structures.
A hydrogel resembling a Rubik's Cube, a trademark of Rubik's Brand Limited, is made via controllable dynamic covalent interactions. Its layers can be rotated either horizontally or vertically to produce new patterns. Ex situ modification or a chemical stimulus can also produce new color arrangements. The creation of multiple patterns may allow for potential applications in patterns‐related material research.
An electrocatalytic methanol oxidation reaction (MOR) is proposed to replace oxygen evolution reaction (OER) in water electrolysis owing to the favorable thermodynamics of MOR than OER. However, ...there is still a competition between the MOR and the OER when the applied potential is in the conventional OER zone. How to inhibit OER while maintaining efficient MOR is an open and challenging question, and there are few reports focusing on this thus far. Herein, by taking NiFe layered double hydroxide (LDH) as a model catalyst due to its intrinsically high catalytic activity for the OER, the perspective of inhibiting OER is shown and thus promoting MOR through a heterogenous engineering of NiFe‐LDH. The engineered heterostructure comprising NiFe‐LDH and in situ formed NiFe‐hexylaminobenzene (NiFe‐HAB) coordination polymer exhibits outstanding electrocatalytic capability for methanol oxidation to formic acid (e.g., the Faradaic efficiencies (FEs) of formate product are close to 100% at various current densities, all of which are much larger than those (53–65%) on unmodified NiFe‐LDH). Mechanism studies unlock the modification of NiFe‐HAB passivates the OER activity of NiFe‐LDH through tailoring the free energies for element reaction steps of the OER and increasing the free energy of the rate‐determining step, consequently leading to efficient MOR.
The engineered novel heterostructure comprising NiFe‐LDH and in situ formed NiFe‐hexylaminobenzene (NiFe‐HAB) coordination polymer exhibits outstanding electrocatalytic capability for methanol oxidation to formic acid. Mechanism studies unlock the modification of NiFe‐HAB passivates the OER activity of NiFe‐LDH through tailoring the free energies for element reaction steps of the OER and increasing the free energy of the rate‐determining step.
Development of high‐performance and low‐cost nonprecious metal electrocatalysts is critical for eco‐friendly hydrogen production through electrolysis. Herein, a novel nanoflower‐like electrocatalyst ...comprising few‐layer nitrogen‐doped graphene‐encapsulated nickel–copper alloy directly on a porous nitrogen‐doped graphic carbon framework (denoted as Nix
Cuy
@ NG‐NC) is successfully synthesized using a facile and scalable method through calcinating the carbon, copper, and nickel hydroxy carbonate composite under inert atmosphere. The introduction of Cu can effectively modulate the morphologies and hydrogen evolution reaction (HER) performance. Moreover, the calcination temperature is an important factor to tune the thickness of graphene layers of the Nix
Cuy
@ NG‐NC composites and the associated electrocatalytic performance. Due to the collective effects including unique porous flowered architecture and the synergetic effect between the bimetallic alloy core and graphene shell, the Ni3Cu1@ NG‐NC electrocatalyst obtained under optimized conditions exhibits highly efficient and ultrastable activity toward HER in harsh environments, i.e., a low overpotential of 122 mV to achieve a current density of 10 mA cm−2 with a low Tafel slope of 84.2 mV dec−1 in alkaline media, and a low overpotential of 95 mV to achieve a current density of 10 mA cm−2 with a low Tafel slope of 77.1 mV dec−1 in acidic electrolyte.
A novel nanoflower‐like electrocatalyst comprising few‐layer nitrogen‐doped graphene‐encapsulated nickel–copper alloy on a porous nitrogen‐doped graphic carbon framework is synthesized by a facile and scalable method, and exhibits high activity and excellent stability for hydrogen evolution due to the collective effects, including unique porous flowered architecture and the synergetic effect between the bimetallic alloy core and the graphene shell.
A facile approach for the preparation of supramolecular polymer‐based fluorescent nanoparticles (FNPs) is reported. FNPs with homogeneous shape and size distribution are fabricated from ...low‐molecular‐weight molecules, and thus, different compositional constituents can be efficiently incorporated via copolymerization. The emission color of the FNPs covers a wide region from blue to near infrared and can be easily tuned using efficient excitation energy transfer. The photoswitchable fluorescent nanoparticles with high on–off fluorescence contrast are also simply prepared by copolymerization of monomers containing a fluorophore and a photochromic unit. Our FNPs are successfully applied in living cell imaging and as fluorescent inks.
A new set of fluorescent nanoparticles (FNPs) are fabricated from hydrogen‐bonded supramolecular polymers. Their preparation is straightforward, and nanoparticles with homogeneous shape and size are obtained. The emission color of the FNPs covers a wide region from blue to near infrared and is easily tunable by excitation energy transfer. These FNPs are successfully used in bioimaging and as fluorescent inks.
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