Semiconductor polymeric graphitic carbon nitride (g-C
3
N
4
) photocatalysts have attracted dramatically growing attention in the field of the visible-light-induced hydrogen evolution reaction (HER) ...because of their facile synthesis, easy functionalization, attractive electronic band structure, high physicochemical stability and photocatalytic activity. This review article presents a panorama of the latest advancements in the rational design and development of g-C
3
N
4
and g-C
3
N
4
-based composite photocatalysts for HER application. Concretely, the review starts with the development history, synthetic strategy, electronic structure and physicochemical characteristics of g-C
3
N
4
materials, followed by the rational design and engineering of various nanostructured g-C
3
N
4
(
e.g.
thinner, highly crystalline, doped, and porous g-C
3
N
4
) photocatalysts for HER application. Then a series of highly efficient g-C
3
N
4
(
e.g.
, metal/g-C
3
N
4
, semiconductor/g-C
3
N
4
, metal organic framework/g-C
3
N
4
, carbon/g-C
3
N
4
, conducting polymer/g-C
3
N
4
, sensitizer/g-C
3
N
4
) composite photocatalysts are exemplified. Lastly, this review provides a comprehensive summary and outlook on the major challenges, opportunities, and inspiring perspectives for future research in this hot area on the basis of pioneering works. It is believed that the emerging g-C
3
N
4
-based photocatalysts will act as the "holy grail" for highly efficient photocatalytic HER under visible-light irradiation.
Graphitic carbon nitrides and their composites with various morphologies and bandgaps engineered for the hydrogen evolution reaction under visible light are reviewed.
An unconventional organic molecule (TBBU) showing obvious long‐lived room temperature phosphorescence (RTP) is reported. X‐ray single crystal analysis demonstrates that TBBU molecules are packed in a ...unique fashion with side‐by‐side arranged intermolecular aromatic rings, which is entirely different from the RTP molecules reported to date. Theoretical calculations verify that the extraordinary intermolecular interaction between neighboring molecules plays an important role in RTP of TBBU crystals. More importantly, the polymer film doped with TBBU inherits its distinctive RTP property, which is highly sensitive to oxygen. The color of the doped film changes and its RTP lifetime drops abruptly through a dynamic collisional quenching mechanism with increasing oxygen fraction, enabling visual and quantitative detection of oxygen. Through analyzing the grayscale of the phosphorescence images, a facile method is developed for rapid, visual, and quantitative detection of oxygen in the air.
Love is like oxygen: An unconventional organic molecule, TBBU, showing obvious long‐lived room‐temperature phosphorescence (RTP) is synthesized for visual and quantitative detection of oxygen (see picture: blue spheres; TBBU: B green, N blue, O red).
Graphitic carbon nitrides (g-C3N4) are a class of burgeoning fluorescent polymeric materials and have received tremendous attention in the biomedical fields because of their unique optical and ...electronic properties. In this review, we systematically summarize synthetic strategies for the preparation of g-C3N4-based materials, and outline their recent advances in various biomedical applications such as diagnostic imaging, therapeutic applications, biosensors and antibacterial applications. In addition, biosafety and toxicity evaluations of g-C3N4-based materials are also in-depth discussed. Furthermore, the state-of-the-art progress, challenges and perspectives of g-C3N4-based materials in biomedical applications are highlighted and discussed in detail. It is believed that the emerging g-C3N4-based biomaterials can realize the actual biomedical applications via unremitting efforts of scientific researchers in the near future.
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•Our method is inherently a simple, mild, green, and controllable method.•The prepared Ag/PSNM products are a novel nanocomposite.•The prepared Ag/PSNM products possess good ...temperature/pH responsive properties and improved thermal properties.•The prepared Ag/PSNM products exhibit high catalytic activities and good storage stabilities.
A facile strategy has been developed for the preparation of novel silver/poly(styrene-N-isopropylacrylamide-methacrylic acid) (Ag/PSNM) nanocomposite spheres with high catalytic activity and good storage stability. Silver (Ag) nanoparticles are successfully deposited on poly(styrene-N-isopropylacrylamide-methacrylic acid) (PSNM) spheres surfaces via in situ reduction and simultaneously protected by polyvinylpyrrolidone (PVP). The prepared Ag/PSNM nanocomposite spheres show good temperature/pH responsive property and improved thermal property. Moreover, they also exhibit high catalytic activity and good recyclability for the catalytic reduction of methylene blue (MB) to leuco methylene blue (LMB). The result of clock reaction indicate that the redox reaction generates a colorless (LMB) solution which easily reverts back to blue (MB) in air. The catalytic activity increase with the increasing of temperature and the reaction rate constant (k) follows the typical Arrhenius-type dependence on temperature. In addition, the prepared Ag/PSNM nanocomposite spheres show good storage stability and the catalytic activity remains almost unchanged after storage for 90days at room temperature. Therefore, the prepared Ag/PSNM nanocomposite spheres can have a highly potential use in the catalytic degradation of organic dyes in wastewater treatment applications.
Ag-based nanoparticles (NPs) catalysts have recently attracted increasing attention in NaBH
4
-assisted nitrophenol reduction, especially in 4-nitrophenol (4-NP) reduction. Moreover, Ag-based NPs ...catalysts are considered to be very promising for practical applications because of their fascinating advantages, e.g., easy preparation, relatively low cost and less toxicity, high activity and good stability. Basically, the size and shape of Ag NPs are well known as the key factors for achieving highly efficient catalytic reduction of 4-NP. In this review, three highly efficient Ag-based NPs catalysts (supported Ag NPs, anisotropic Ag NPs and bimetallic Ag NPs) are highlighted for the 4-NP reduction, including the catalytic mechanism and reaction rate caused by their adjustments in size and shape. Although high catalytic activity has been demonstrated by several Ag-based NPs catalysts, further improvement in the catalytic performance is still desired. In terms of the most recent progress in Ag-based NPs catalysts for 4-NP reduction, this review provides a comprehensive assessment on the material selection, synthesis and catalytic characterizations of these catalysts. Moreover, this review aims to correlate the catalytic performance of Ag-based NPs catalysts with their size and shape, guiding the development of novel cost-effective and high-performance catalysts.
Recently a new high-order formulation for 1D conservation laws was developed by Huynh using the idea of “flux reconstruction”. The formulation was capable of unifying several popular methods ...including the discontinuous Galerkin, staggered-grid multi-domain method, or the spectral difference/spectral volume methods into a single family. The extension of the method to quadrilateral and hexahedral elements is straightforward. In an attempt to extend the method to other element types such as triangular, tetrahedral or prismatic elements, the idea of “flux reconstruction” is generalized into a “lifting collocation penalty” approach. With a judicious selection of solution points and flux points, the approach can be made simple and efficient to implement for mixed grids. In addition, the formulation includes the discontinuous Galerkin, spectral volume and spectral difference methods as special cases. Several test problems are presented to demonstrate the capability of the method.
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•Novel self-stabilized fluorescent micelles were built for amine detection in water.•Chromophores with aggregation induced emission characteristics organized into cores.•Water-soluble ...polymer corona of the micelles grabbed organic amines out of water.•The sensors allowed rapid detection of amines at a concentration of 8 μg/L.
A kind of self-stabilized micelles of fluorescent block copolymers are constructed for rapid and sensitive detection of aliphatic amines in water based on capture-report strategy. An amphiphilic triblock copolymer functionalized with aggregation induced emission (AIE) chromophores self assembles into micelles with core-shell structures in aqueous solution. Hydrophobic AIE chromophores organize into cores, where hydrophobic interaction among the AIE chromophores inhibits the micelles from disassembling. The cores of AIE chromophores are surrounded by a corona of water-soluble polymer segments, endowing the micelles with superior dispersibility in water. Water-soluble polymer segments capture organic amines in water due to preferential hydrophobic interactions between them. The enriched amines in the corona subsequently diffuse into hydrophobic cores of micelles, quenching fluorescence of the AIE chromophores. The fluorescent micelles allow rapid detection of aliphatic amines in the order of seconds at a concentration as low as 8 μg/L.
Endothelial senescence plays crucial roles in diabetic vascular complication. Recent evidence indicated that transient hyperglycaemia could potentiate persistent diabetic vascular complications, a ...phenomenon known as "metabolic memory." Although SIRT1 has been demonstrated to mediate high glucose-induced endothelial senescence, whether and how "metabolic memory" would affect endothelial senescence through SIRT1 signaling remains largely unknown. In this study, we investigated the involvement of SIRT1 axis as well as the protective effects of resveratrol (RSV) and metformin (MET), two potent SIRT1 activators, during the occurrence of "metabolic memory" of cellular senescence (senescent "memory"). Human umbilical vascular endothelial cells (HUVECs) were cultured in either normal glucose (NG)/high glucose (HG) media for 6 days, or 3 days of HG followed by 3 days of NG (HN), with or without RSV or MET treatment. It was shown that HN incubation triggered persistent downregulation of deacetylase SIRT1 and upregulation of acetyltransferase p300, leading to sustained hyperacetylation (at K382) and activation of p53, and subsequent p53/p21-mediated senescent "memory." In contrast, senescent "memory" was abrogated by overexpression of SIRT1 or knockdown of p300. Interestingly, we found that SIRT1 and p300 could regulate each other in response to HN stimulation, suggesting that a delicate balance between acetyltransferases and deacetylases may be particularly important for sustained acetylation and activation of non-histone proteins (such as p53), and eventually the occurrence of "metabolic memory." Furthermore, we found that RSV or MET treatment prevented senescent "memory" by modulating SIRT1/p300/p53/p21 pathway. Notably, early and continuous treatment of MET, but not RSV, was particularly important for preventing senescent "memory." In conclusion, short-term high glucose stimulation could induce sustained endothelial senescence via SIRT1/p300/p53/p21 pathway. RVS or MET treatment could enhance SIRT1-mediated signaling and thus protect against senescent "memory" independent of their glucose lowering mechanisms. Therefore, they may serve as promising therapeutic drugs against the development of "metabolic memory."
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Polyethylene-
-polypeptide copolymers are biologically interesting, but studies of their synthesis and properties are very few. This paper reports synthesis and characterization of well-defined ...amphiphilic polyethylene-
-poly(L-lysine) (PE-
-PLL) block copolymers by combining nickel-catalyzed living ethylene polymerization with controlled ring-opening polymerization (ROP) of ε-benzyloxycarbonyl-L-lysine-
-carboxyanhydride (Z-Lys-NCA) and sequential post-functionalization. Amphiphilic PE-
-PLL block copolymers self-assembled into spherical micelles with a hydrophobic PE core in aqueous solution. The pH and ionic responsivities of PE-
-PLL polymeric micelles were investigated by means of fluorescence spectroscopy, dynamic light scattering, UV-circular dichroism, and transmission electron microscopy. The variation of pH values led to the conformational alteration of PLL from α-helix to coil, thereby changing the micelle dimensions.
Chiral (1S)- and (1R)-camphyl α-diimine nickel complexes were synthesized respectively with (1S)-(+) camphorquinone and (1R)-(−) camphorquinone as raw reagents and used as catalyst precursors for ...olefin polymerizations. It is found that the ligand chirality has no influence on catalytic activity and regioselectivity for olefin polymerizations. Ethylene, propylene, 1-hexene, and 4-methyl-1-pentene polymerizations with the camphyl α-diimine nickel activated by AlEt2Cl can exhibit some living characteristics under the optimized conditions. The resultant polypropylenes and poly(1-hexene)s have significantly narrow molecular weight distributions (PDI < 1.2) in a wide temperature range, even at an elevated temperature of 70 °C. Sustainable period of the linear relationship of M n vs polymerization time depends on temperature for propylene and 1-hexene polymerizations. Additionally, high 1,3-enchainment fraction of 45% is observed even at −60 °C for propylene polymerization using the camphyl α-diimine catalyst due to 2,1-insertion of propylene and chain walking.
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