The necessity of sustainable development in the chemical industry has continuously drawn attention to find safe, environmentally friendly and atom-economic chemical processes, which is defined in the ...12 principles of green chemistry. Merging photoredox catalysis and reversible addition-fragmentation chain transfer (RAFT) polymerisation, the photoinduced electron/energy transfer (PET)-RAFT process has opened up a new way of performing reversible deactivation radical polymerisation for well-defined polymer synthesis using light as an external stimulus. While providing an increased level of control (spatiotemporal, wavelength, and intensity control) over the polymerisation, PET-RAFT has many attractive attributes (abundant catalyst availability, catalyst recyclability, selectivity and oxygen tolerance) to be green and sustainable, which is intriguing for precision polymer manufacturing in industry.
Photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) process has opened up a new way of precision polymer manufacturing to satisfy the concept of green chemistry.
Natural biopolymers, such as DNA and proteins, have uniform microstructures with defined molecular weight, precise monomer sequence, and stereoregularity along the polymer main chain that affords ...them unique biological functions. To reproduce such structurally perfect polymers and understand the mechanism of specific functions through chemical approaches, researchers have proposed using synthetic polymers as an alternative due to their broad chemical diversity and relatively simple manipulation. Herein, we report a new methodology to prepare sequence-controlled and stereospecific oligomers using alternating radical chain growth and sequential photoinduced RAFT single unit monomer insertion (photo-RAFT SUMI). Two families of cyclic monomers, the indenes and the N-substituted maleimides, can be alternatively inserted into RAFT agents, one unit at a time, allowing the monomer sequence to be controlled through sequential and alternating monomer addition. Importantly, the stereochemistry of cyclic monomer insertion into the RAFT agents is found to be trans-selective along the main chains due to steric hindrance from the repeating monomer units. All investigated cyclic monomers provide such trans-selectivity, but analogous acyclic monomers give a mixed cis- and trans-insertion.
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IJS, KILJ, NUK, PNG, UL, UM
Graphene oxide (GO) has shown remarkable performance in the multiple-equilibrium-route adsorption (MER) process, which is characterized by further activation of GO through an in-situ reduction ...process based on single-equilibrium-route adsorption (SER), generating new adsorption sites and achieving an adsorption capacity increase. However, the effect of GO on MER adsorption in lateral size and thickness is still unclear. Here, GO sheets were sonicated for different lengths of time, and the adsorption of MER and SER was investigated at three temperatures to remove the typical cationic dye, acridine orange (AO). After sonication, we found that freshly prepared GO was greatly reduced in lateral size and thickness. In about 30 min, the thickness of GO decreased dramatically from several atomic layers to fewer atomic layers to a single atomic layer, which was completely stripped off; after that, the monolayer lateral size reduction dominated until it remained constant. Surface functional sites, such as hydroxyl groups, showed little change in the experiments. However, GO mainly reduces the C=O and C-O bonds in MER, except for the conjugated carbon backbone (C-C). The SER adsorption kinetics of all temperatures fitted the pseudo-first-order and pseudo-second-order models, yet room temperature preferred the latter. An overall adsorption enhancement appeared as sonication time, but the equilibrium capacity of SER GO generally increased with thickness and decreased with the single-layer lateral size, while MER GO conversed concerning the thickness. The escalated temperature facilitated the exfoliation of GO regarding the adsorption mechanism. Thus, the isotherm behaviors of the SER GO changed from the Freundlich model to Langmuir as size and temperature changed, while the MER GO were all of the Freundlich. A record capacity of ~4.3 g of AO per gram of GO was obtained from the MER adsorption with a sixty-minute ultrasonicated GO at 313.15 K. This work promises a cornerstone for MER adsorption with GO as an adsorbent.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
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•Overview of the recent progress in biomimetic or bioinspired synthesis of metal–organic frameworks and metal–phenolic networks.•Biomimetic growth from synthetic polymers.•Biomimetic ...growth from biomolecules.•Biomimetic growth from and around organisms.
Biomimetic synthesis merges the unprecedented properties of biominerals with the unique characteristics of synthetic materials to yield hybrid materials with hierarchical morphologies and tunable properties difficult to achieve via traditional physical or chemical synthesis. The biomimetic synthesis of coordination networks, such as metal–organic frameworks and amorphous coordination networks, is a relatively new member in the family of bioinspired or biomimetic materials. There is a growing interest in synthesizing organic–inorganic hybrid materials using biomimetic routes to exploit the synergistic properties of both the synthetic materials and biomaterials. These hybrid biomimetic materials show potential ground-breaking applications in nanotechnology and biomedicine ranging from gas separation to drug delivery and biocatalysis. In this review, we summarize the current state of synthesizing coordination networks using biomimetic routes, utilizing three major classes of materials, including synthetic polymers, biomolecules, and living entities. The biomimetic synthesis of coordination networks from these functional substrates has the potential to address global challenges in energy, healthcare, and environmental sustainability.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The composite hydrogel performs integrated PTT for osteogenesis and bacterial eradication. With NIR stimulation, precisely controlled-release of BMP-2 and tannin by the hydrophobic phenomenon of ...volume contraction along with local heating helps the osteogenic differentiation of BMSCs, and slow release of natural component O-HACC in combination with hyperthermia exhibits excellent antibacterial efficiency by relative low temperature to avoid potential unexpected damage.
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•A NIR-responsive and multi-functional hydrogel system packaged with bioactive factors was fabricated.•Programmable NIR irradiation performed anti-microbial, anti-oxidative and pro-osteogenic functions respectively.•Administration of controllable photothermal strategy achieved a synergistic therapeutic effect on bone regeneration.
Progress toward developing next-generation biomaterials applied in complex bone defect is expected to effectively integrate osteogenic and anti-bacteria capability. However, current biomaterials often achieve the two functions separately. Inspired by photothermal effect, exogenous light-induced thermal variations can efficiently facilitate bone regeneration and bacteria eradication. Here, a bioactive hydrogel BMP-2@PNH-TA with simultaneously osteogenic and anti-bacterial capacities is presented, which is based on the near infrared (NIR) induced photothermal effect to perform integrated photothermal therapy (PTT). In detail, photothermal effect and photothermal-controlled release of osteogenic and anti-bacterial factors through sponge-like effect could exert integrated influence on bone regeneration under complex situation. The composite hydrogel can mediate pro-osteogenesis under mild temperature and controlled release of BMP-2 and tannin in response to NIR stimulation with low power, while efficiently eradicate bacteria via controlled release of O-HACC and thermal effect with high power. The customized PTT strategy significantly shortened the duration time of bone regeneration up to almost 50% in rat cranial bone defect. It is anticipated that the concept of integrated PTT for bone regeneration will cast new insights into developing high-performance therapeutic strategy with combined biological functions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Recapitulating the natural extracellular physical microenvironment has emerged as a promising method for tissue regeneration, as multiple physical interventions, including ultrasound, thermal and ...electrical therapy, have shown great potential. However, simultaneous coupling of multiple physical cues to highly bio-mimick natural characteristics for improved tissue regeneration still remains formidable. Coupling of intrinsic electrical and mechanical cues has been regarded as an effective way to modulate tissue repair. Nevertheless, precise and convenient manipulation on coupling of mechano-electrical signals within extracellular environment to facilitate tissue regeneration remains challengeable. Herein, a photothermal-sensitive piezoelectric membrane was designed for simultaneous integration of electrical and mechanical signals in response to NIR irradiation. The high-performance mechano-electrical coupling under NIR exposure synergistically triggered the promotion of osteogenic differentiation of stem cells and enhances bone defect regeneration by increasing cellular mechanical sensing, attachment, spreading and cytoskeleton remodeling. This study highlights the coupling of mechanical signals and electrical cues for modulation of osteogenesis, and sheds light on alternative bone tissue engineering therapies with multiple integrated physical cues for tissue repair.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
With the intensification of global climate problems, electric heating has recently attracted much attention as a clean and low-carbon heating method. Carbon nanotubes (CNTs) are an ideal medium for ...electric heating applications due to their excellent mechanical, electrical, and thermal properties. The preparation of electrothermal films based on an aqueous CNT dispersion as a raw material is environmentally friendly. However, in the traditional one-step filtration method, the residual excess dispersant and the small aspect ratio of the CNTs in the preparation process limit the performance of electrothermal CNT films. In this paper, we report a two-step filtration method that removes the free dispersant and small CNTs in the first filtration step and obtains denser CNT films by controlling the pores of the filter membrane in the second filtration step. The results suggest that, compared to the CNT1 film obtained from one-step filtration, the CNT1-0.22 film, obtained from two-step filtration using 1 and 0.22 μm membranes, has a smoother and flatter surface, and the surface resistance is 80.0 Ω sq−1, which is 29.4% lower. The convective radiation conversion efficiency of the CNT1-0.22 film is 3.36 mW/°C, which is 36.1% lower. We anticipate that such CNT films could be widely applied in building thermal insulation and underfloor heating.
Reduced photosynthesis results directly from nitrogen or water deficiency in wheat plants, and leads to a decrease in grain yield. In this study, by measuring the effects of water and N deficiencies, ...both individually and combined, we characterized the responses of wheat (Triticum aestivum L. Yumai 49–198) plants to these two deficiencies using physiological measurements and comparative proteomics. Significant decreases in grain yield and leaf photosynthetic performance were observed in all deficiency conditions, and 106 photosynthetic proteins that showed responses were identified. Nitrogen deficiency induced the least change in photosynthetic proteins, and similar changes in most of these proteins were also observed for the combined nitrogen and water deficiencies. Water deficiency induced the largest change in photosynthetic proteins and resulted in the lowest 1000-kernel weight. Severe decreases in photosynthesis in both the water-deficiency and combined N and water deficiency groups were reflected mainly in an imbalanced ATP/NADPH ratio associated with the light reaction, which influences carbon metabolism in the Calvin cycle. Photorespiration was respectively stimulated or inhibited by N or water deficiency, while suppression of photorespiratory flux and activation of nitrogen recycling were observed in the combined N and water deficiency treatments. Comparison of photosynthetic proteins between experimental sites suggested that precipitation affected linear electron flow in the photoreaction, and thus photosynthetic efficiency. Our results provide a baseline for future studies of the roles of these photosynthetic proteins in the response to N or water deficiency and their effect on 1000-kernel weight.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Facing the growing environmental issues provoked by the use of nondegradable polymers in many fields (for example, packing, building, and clothing), tremendous efforts have been made to explore ...photodegradable materials to alleviate the increase in plastic pollution. Photodegradable materials would exploit significant advantages presented by the use of light, such as abundance, safety and the ability to easily tune intensity and wavelength. In particular, photo‐induced depolymerisation has received increasing attention, which could enable polymers to degrade to their original monomers or small molecules under certain photoirradiation conditions. Most importantly, the obtained molecules or monomers via photo‐induced depolymerisation could be conveniently recycled or further transformed to other high‐value‐added products, which is of great benefit for environmental protection. This Review summarizes recent advances in the growing field of photo‐induced depolymerisation and also considers future challenges that must be addressed. It aims to encourage new researchers to enter this flourishing area and presents a brief guide to the field.
Relax and unwind: Recent advances and future challenges in the field of photo‐induced depolymerisation have been summarized, focusing the discussion on the light sources employed (UV, visible and IR/NIR lights), natural and synthetic polymers, and depolymerisation mechanisms. This Review aims to encourage new researchers to enter this flourishing area and presents as a brief guidance.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The Yunnan-Guizhou Plateau in southwest China lies at the intersection between East and South Asia, and is characterised by highly complex vegetation ranging from subtropical forest to open ...grassland. There is a long history of human modification to the landscape, but we know surprisingly little of the biogeography of open habitats such as grassy biomes in the region. To investigate the historical continuity of grassy biomes in southwest China, we examined the biogeographies and evolutionary histories of two widespread and dominant C4 grasses, Themeda triandra and Heteropogon contortus, in Yunnan and southern Sichuan provinces, using chloroplast DNA markers in combination with climate data. We discovered that cool- and warm-adapted lineages have been widely distributed across the Yunnan-Guizhou Plateau for at least the last 2 million years, pre-dating any possible anthropogenic impact. Moreover, the high genetic diversity and strong spatial structure of both species suggests the continuous presence of multiple large populations, rather than a recent expansion from the dry valleys in response to anthropogenic deforestation. This is the first evidence for the long-term existence of extensive populations of C4 grasses in this region outside the dry valleys, and calls for a reappraisal of the conservation value of these grass-dominated landscapes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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