Abstract
Controlled growth of well-oriented metal-organic framework nanoarrays on requisite surfaces is of prominent significance for a broad range of applications such as catalysis, sensing, optics ...and electronics. Herein, we develop a highly flexible soft nanobrush-directed synthesis approach for precise in situ fabrication of MOF nanoarrays on diverse substrates. The soft nanobrushes are constructed via surface-initiated living crystallization-driven self-assembly and their active poly(2-vinylpyridine) corona captures abundant metal cations through coordination interactions. This allows the rapid heterogeneous growth of MOF nanoparticles and the subsequent formation of MIL-100 (Fe), HKUST-1 and CUT-8 (Cu) nanoarrays with tailored heights of 220~1100 nm on silicon wafer, Ni foam and ceramic tube. Auxiliary functional components including metal oxygen clusters and precious metal nanoparticles can be readily incorporated to finely fabricate hybrid structures with synergistic features. Remarkably, the MIL-100 (Fe) nanoarrays doped with Keggin H
3
PMo
10
V
2
O
40
dramatically boost formaldehyde selectivity up to 92.8% in catalytic oxidation of methanol. Moreover, the HKUST-1 nanoarrays decorated with Pt nanoparticles show exceptional sensitivity to H
2
S with a ppb-level detection limit.
We have found that the width and shape (from rectangular to elliptical, to almost circular in cross-section) of the crystalline core of fiberlike micelles of polyferrocenyldimethylsilane (PFDMS) ...diblock copolymers can be varied by altering the degree of polymerization of PFDMS, and also the chemistry of the complementary corona-forming block. This enabled detailed studies of living crystallization-driven self-assembly (CDSA) processes that involved the addition of unimers with a short, crystallizable core-forming PFDMS block to a seed solution of short micelles with a large diameter crystalline core, derived from block copolymers with a longer PFDMS block. The morphology of resultant micelles was found to be highly dependent on the polarity of the solvent and temperature. For example, linear micelles were formed in less polar solvents (which are moderately poor solvents for PFDMS) and/or at higher temperatures. In contrast, the formation of branched structures could be “switched on” when the opposite conditions were used. Thus, the use of more polar solvents (which are very poor solvents for PFDMS) and ambient or subambient temperatures allowed the formation of branched micelles and block comicelles with variable and spatially distinct corona chemistries, including amphiphilic nanostructures. Rapid crystallization of added unimers at the seed micelle termini under nonequilibrium self-assembly conditions appears to facilitate the formation of the branched micellar structures as a kinetically trapped morphology. This is evidenced by the transformation of the branched micelles into linear micelles on heating at elevated temperatures.
Abstract Porous frameworks constructed via noncovalent interactions show wide potential in molecular separation and gas adsorption. However, it remains a major challenge to prepare these materials ...from low-symmetry molecular building blocks. Herein, we report a facile strategy to fabricate noncovalent porous crystals through modular self-assembly of a low-symmetry helicene racemate. The P and M enantiomers in the racemate first stack into right- and left-handed triangular prisms, respectively, and subsequently the two types of prisms alternatively stack together into a hexagonal network with one-dimensional channels with a diameter of 14.5 Å. Remarkably, the framework reveals high stability upon heating to 275 °C, majorly due to the abundant π-interactions between the complementarily engaged helicene building blocks. Such porous framework can be readily prepared by fast rotary evaporation, and is easy to recycle and repeatedly reform. The refined porous structure and enriched π-conjugation also favor the selective adsorption of a series of small molecules.
The consideration of nonextensivity effects is crucial to the accurate diagnosis of plasma parameters; common plasma nonextensive parameters include electron nonextensive parameter and ion ...nonextensive parameter, and the former can be measured, while the ion nonextensive parameter cannot be measured yet. Here we show the measurement of ion nonextensive parameter of plasma based on the theory of nonextensive geodesic acoustic modes. We assume that the plasma to be measured can be described by nonextensive statistical mechanics, and on this basis, the nonextensive geodesic acoustic mode theory is established. Utilizing this theory, we have measured the ion nonextensive parameter Formula: see text which cannot be diagnosed even by a nonextensive single electric probe. Our research points out that the proposed measurement method of ion nonextensive parameter may play a role in plasma diagnosis and will help us to grasp the nonextensivity of plasma more precisely. We hope the proposed method of ion nonextensive parameter diagnosis based on the nonextensive geodesic acoustic mode theory can be the starting point of more complex ion nonextensive parameter diagnosis methods. In addition, the measurement of ion nonextensive parameter is closely related to the study of various plasma waves, instabilities, turbulence and abnormal transport, and a defined and quantitative test of nonextensive geodesic acoustic mode theory will bound up deeply with such developments.
Let's twist again: The chirality of a helical propeller-like micelle has been memorized by functional groups on the mesopore surface of chiral mesoporous silicas. Such imprinted supramolecular ...chirality can be transcripted to poly(propiolic acid) sodium salt and tetraphenylporphine tetrasulfonic acid (see picture), and recognized by B-DNA.
Toroidal nanostructures are of growing importance due to their unique geometry and potential utility in materials fabrication. Although a variety of amphiphilic block copolymers has been shown to ...self-assemble into toroidal micelles, the conventional methods used are often very slow with little control over the size of the resulting nanostructures. Here, we report a rapid and efficient synthetic route to prepare toroidal micelles of near uniform diameter through the cooperative coassembly of amorphous blends of polyferrocenylsilane block copolymer and homopolymer, where the degree of polymerization of the core-forming metalloblock in the former is greater than for the latter. The self-assembly process is accomplished within a few minutes, and the ring size of the toroids can be varied between 30 and 90 nm by adjusting the mass ratio of the block copolymer and homopolymer. The kinetic stability of the resulting toroidal micelles can be enhanced by frustrating core crystallization through solvent modulation and the toroids can also be readily used as templates to fabricate circular arrays of metal nanoparticles.
Second near-infrared (NIR-II) fluorescence imaging is a recently emerged technique and is highly useful for accurate diagnosis of cancer. Although a diverse array of fluorescent nanomaterials have ...been developed to enable NIR-II fluorescence in various situations, they normally fail to unify the clinical techniques, such as computed tomography (CT) and magnetic resonance imaging (MRI). Therefore, exploiting multimodal agents to integrate the newly emerged NIR-II fluorescence and traditional clinical techniques would be of key significance. Here, we report a rational fabrication of neodymium (Nd)-doped gadolinium tungstate nanoparticles (NPs) that are subsequentially decorated with a hydrophilic layer and demonstrate that they can achieve the harmonious integration of NIR-II fluorescence imaging, CT, and MRI. The NIR-II fluorescence emission was activated by an incident light with discrete wavelength ranging from 250 to 810 nm. NIR-II fluorescence-CT-MRI associated trimodal imaging was subsequently demonstrated for breast cancer by an 808 nm laser, along with the estimation of NIR-II fluorescence imaging for cervical cancer. The integration of newly emerged and traditional clinical imaging techniques highlights the huge potential of rare-earth-doped NPs for multimodal imaging of different types of cancer.
It is a great physical challenge to achieve controlled nuclear fusion in magnetic confinement tokamak and solve energy shortage problem for decades. In tokamak plasma, large-scale plasma instability ...called disruption will halt power production of reactor and damage key components. Prediction and prevention of plasma disruption is extremely urgent and important. However, there is no analytical theory can elucidate plasma disruption physical mechanism yet. Here we show an analytical theory of tokamak plasma disruption based on nonextensive geodesic acoustic mode theory, which can give the physical mechanism of disruption. The proposed theory has not only been confirmed by experimental data of disruption on T-10 device, but also can explain many related phenomena around plasma disruption, filling the gap in physical mechanism of tokamak plasma disruption.
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