Oxide-supported noble metal catalysts have been extensively studied for decades for the water gas shift (WGS) reaction, a catalytic transformation central to a host of large volume processes that ...variously utilize or produce hydrogen. There remains considerable uncertainty as to how the specific features of the active metal-support interfacial bonding-perhaps most importantly the temporal dynamic changes occurring therein-serve to enable high activity and selectivity. Here we report the dynamic characteristics of a Pt/CeO
system at the atomic level for the WGS reaction and specifically reveal the synergistic effects of metal-support bonding at the perimeter region. We find that the perimeter Pt
- O vacancy-Ce
sites are formed in the active structure, transformed at working temperatures and their appearance regulates the adsorbate behaviors. We find that the dynamic nature of this site is a key mechanistic step for the WGS reaction.
Framework nitrogen atoms of carbon nitride (C3N4) can coordinate with and activate metal sites for catalysis. In this study, C3N4 was employed to harvest visible light and activate Co2+ sites, ...without the use of additional ligands, in photochemical CO2 reduction. Photocatalysts containing single Co2+ sites on C3N4 were prepared by a simple deposition method and demonstrated excellent activity and product selectivity toward CO formation. A turnover number of more than 200 was obtained for CO production using the synthesized photocatalyst under visible-light irradiation. Inactive cobalt oxides formed at relatively high cobalt loadings but did not alter product selectivity. Further studies with X-ray absorption spectroscopy confirmed the presence of single Co2+ sites on C3N4 and their important role in achieving selective CO2 reduction.
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IJS, KILJ, NUK, PNG, UL, UM
In this work, we propose a simple and enzyme-free strategy for sensitive and selective DNA detection by using two different types of molecular beacons (MBs), MB1 and MB2. In this method, the target ...DNA binds with and restores the fluorescence of MB1 first. Then, MB2 hybridizes with MB1 and free the target, which is used to trigger another reaction cycle. The cycling use of the target and the employment of bi-MBs amplify the fluorescence intensity for sensitive DNA detection. The detection limit of this method was obtained as 10 pM, which is about 2 orders of magnitude sensitive than the conventional MB-based approaches.
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IJS, KILJ, NUK, PNG, UL, UM
Metal ion detection is critical in a variety of areas. The past decade has witnessed great progress in the development of metal ion sensors using functional nucleic acids (FNAs) and nanomaterials. ...The former has good recognition selectivity toward metal ions and the latter possesses unique properties for enhancing the performance of metal ion sensors. This review offers a summary of FNA- and nanomaterial-based metal ion detection methods. FNAs mainly include DNAzymes, G-quadruplexes, and mismatched base pairs and nanomaterials cover gold nanoparticles (GNPs), quantum dots (QDs), carbon nanotubes (CNTs), and graphene oxide (GO). The roles of FNAs and nanomaterials are introduced first. Then, various methods based on the combination of different FNAs and nanomaterials are discussed. Finally, the challenges and future directions of metal ion sensors are presented.
•The development of biosensors for metal ion detections that employ both functional nucleic acids (FNAs) and nanomaterials is intensively reviewed.•FNAs mainly include DNAzymes, G-quadruplexes, and mismatched base pairs and advanced nanomaterials cover gold nanoparticles, quantum dots, carbon nanotubes, and graphene oxide.•The recognition principles and signal conversion mechanisms of FNAs and nanomaterials are introduced.•The challenges and future directions of metal ion sensors are also discussed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Quantifying RNAs in their spatial context is crucial to understanding gene expression and regulation in complex tissues. In situ transcriptomic methods generate spatially resolved RNA profiles in ...intact tissues. However, there is a lack of a unified computational framework for integrative analysis of in situ transcriptomic data. Here, we introduce an unsupervised and annotation-free framework, termed ClusterMap, which incorporates the physical location and gene identity of RNAs, formulates the task as a point pattern analysis problem, and identifies biologically meaningful structures by density peak clustering (DPC). Specifically, ClusterMap precisely clusters RNAs into subcellular structures, cell bodies, and tissue regions in both two- and three-dimensional space, and performs consistently on diverse tissue types, including mouse brain, placenta, gut, and human cardiac organoids. We demonstrate ClusterMap to be broadly applicable to various in situ transcriptomic measurements to uncover gene expression patterns, cell niche, and tissue organization principles from images with high-dimensional transcriptomic profiles.
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Macromolecular self-assembly has made explosive development in the last several decades, are being extensively explored in the fields of drug delivery, lithography, catalysis, ...molecular electronics, sensors, and so many others. In this review, we summarize the self-assembly of macromolecules such as polymers, dendrimers, molecular nanoparticles, colloids, DNA and proteins, from the aspect of architectural engineering and mainly focus on the periodic and quasi-periodic assembled structures. In particular, simple building blocks can be conjugated together to construct complex macromolecular motifs with different architectures and physical interactions. We first introduce the concept of architectural engineering, then present a brief overview of supramolecular interactions and five main categories of building blocks, including polymer coils, dendrons, rods, discs, and polyhedra. We further discuss the detailed self-assembly behaviors of fifteen types of specific macromolecular motifs involving different building blocks. Special attention is paid to the architectural effect of macromolecular self-assembly. In the end, future perspective on architectural engineering is briefly mentioned.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Frank-Kasper phases, a family of ordered structures formed from particles with spherical motifs, are found in a host of materials, such as metal alloys, inorganic colloids and various types of soft ...matter. All the experimentally observed Frank-Kasper phases can be constructed from the basic units of three fundamental structures called the A15, C15 and Z phases. The Z phase, typically observed in metal alloys, is associated with a relatively large volume ratio between its constituents, and this constraint inhibits its formation in most self-assembled single-component soft-matter systems. We have assembled a series of nanosized shape amphiphiles that comprise a triphenylene core and six polyhedral oligomeric silsesquioxane cages grafted onto it through linkers to give a variety of unconventional structures, which include the Z phase. This structure was obtained through fine tuning of the linker lengths between the core and the peripheral polyhedral oligomeric silsesquioxane cages, and exhibits a relatively large volume asymmetry between its constituent polyhedral particle motifs.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
This paper investigates the bending of asymmetric functionally graded material (FGM) sandwich plates subjected to thermo-mechanical loads in thermal environments. In this paper, a thermo-mechanical ...analysis model for asymmetric FGM sandwich plates is proposed, which contains only four control equations and four unknown variables. The governing equation is obtained through refined shear theory and the principle of virtual work, and the Navier method is used to solve it. Numerical examples of simply supported FGM sandwich plates under thermo-mechanical loads are given to verify the accuracy of the model. Finally, detailed studies are conducted on the bending of asymmetric FGM sandwich plates under thermo-mechanical loads, exploring the effects of various parameter changes on their bending behavior, and providing strong guidance for the application of asymmetric FGM sandwich plates in industrial production practice.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Frank–Kasper (F-K) and quasicrystal phases were originally identified in metal alloys and only sporadically reported in soft materials. These unconventional sphere-packing schemes open up ...possibilities to design materials with different properties. The challenge in soft materials is how to correlate complex phases built from spheres with the tunable parameters of chemical composition and molecular architecture. Here, we report a complete sequence of various highly ordered mesophases by the self-assembly of specifically designed and synthesized giant surfactants, which are conjugates of hydrophilic polyhedral oligomeric silsesquioxane cages tethered with hydrophobic polystyrene tails. We show that the occurrence of these mesophases results from nanophase separation between the heads and tails and thus is critically dependent on molecular geometry. Variations in molecular geometry achieved by changing the number of tails from one to four not only shift compositional phase boundaries but also stabilize F-K and quasicrystal phases in regions where simple phases of spheroidal micelles are typically observed. These complex self-assembled nanostructures have been identified by combining X-ray scattering techniques and real-space electron microscopy images. Brownian dynamics simulations based on a simplified molecular model confirm the architecture-induced sequence of phases. Our results demonstrate the critical role of molecular architecture in dictating the formation of supramolecular crystals with “soft” spheroidal motifs and provide guidelines to the design of unconventional self-assembled nanostructures.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Cellular senescence irreversibly arrests proliferation in response to potentially oncogenic stress. Senescent cells also secrete inflammatory cytokines such as IL-6, which promote age-associated ...inflammation and pathology. HMGB1 (high mobility group box 1) modulates gene expression in the nucleus, but certain immune cells secrete HMGB1 as an extracellular Alarmin to signal tissue damage. We show that nuclear HMGB1 relocalized to the extracellular milieu in senescent human and mouse cells in culture and in vivo. In contrast to cytokine secretion, HMGB1 redistribution required the p53 tumor suppressor, but not its activator ATM. Moreover, altered HMGB1 expression induced a p53-dependent senescent growth arrest. Senescent fibroblasts secreted oxidized HMGB1, which stimulated cytokine secretion through TLR-4 signaling. HMGB1 depletion, HMGB1 blocking antibody, or TLR-4 inhibition attenuated senescence-associated IL-6 secretion, and exogenous HMGB1 stimulated NF-κB activity and restored IL-6 secretion to HMGB1-depleted cells. Our findings identify senescence as a novel biological setting in which HMGB1 functions and link HMGB1 redistribution to p53 activity and senescence-associated inflammation.
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