Developing biodegradable materials such as poly(lactic acid) (PLA) is a promising strategy to reduce the reliance on non‐degradable plastics and the accumulation of those wastes. However, the ...fabrication of high‐performance biodegradable films which integrate excellent mechanical and barrier properties remains a major challenge. To address this problem, the “brick and mortar” structure, one of the most effective biomimetic models, is introduced to improve the comprehensive properties of materials. Here, a PLA‐assisted exfoliation and dispersion method to prepare the PLA coated mica nanosheets (Nano‐mica/PLA) from a natural mineral phlogopite is presented. By introducing the sheer force assembly, a kind of nacre‐inspired nanocomposite film with the “brick and mortar” structure can be fabricated. Such a nacre‐inspired nanocomposite film shows excellent mechanical properties, UV‐shielding, and gas barrier properties. The overall performance of the nacre‐inspired nanocomposite film is superior to commercial plastic films, which will allow it possible to break a path for practical applications of PLA in the field of packaging.
An advanced poly(lactic acid)‐assisted exfoliation and dispersion method has been developed to prepare the poly(lactic acid) coated mica nanosheets. By introducing the sheer force assembly, a nacre‐inspired nanocomposite film with the “brick and mortar” structure is constructed with the high strength, excellent UV‐shielding performance, and barrier properties, which has great application potential in the field of packaging materials.
Boron‐based adhesives have attracted considerable attention in recent years due to their strong adhesive behavior and reversible capacities. However, limited by the humidity sensitivity and poor ...dynamicity, it remains challenging for the boron‐based adhesive materials to realize strong and long‐term adhesion underwater. In this study, a novel boronic ester (BN‐6) with changeable ring strain induced by the heat‐responsive BN coordination bond is designed and synthesized. Due to the low strain of the six‐membered ring at ambient conditions and the high strain of the ten‐membered ring at elevated temperature, BN‐6 exhibits enhanced hydrolytic/thermal stabilities as well as dynamicity. The model dynamic crosslinking polymers containing BN‐6 linkages present significantly improved water‐resistance and recyclability. Specifically, based on the hydrolytically stable whilst kinetically active boronic ester linkage, a strong and recyclable adhesive material is successfully prepared. Long‐term adhesion performance under water and harsh conditions is realized on different substrates, with the maximum adhesion strength of 4.21 MPa. The report provides a novel chemical strategy for designing stable and dynamic boronic ester linkages and the synthesized adhesive has pioneered in the field of long‐term underwater application of boron‐based adhesives.
The authors have synthesized a novel boronic ester with enhanced hydrolytic stability and dynamicity through the reversible transition of ring strain induced by the heat‐responsive BN coordination. Therefore, the adhesive containing this boronic ester exhibits excellent adhesion strength and repeatable long‐term stability under water and harsh environments, which has broken through the bottleneck of underwater application of boron‐based adhesives.
An All‐Natural Wood‐Inspired Aerogel Han, Zi‐Meng; Sun, Wen‐Bin; Yang, Kun‐Peng ...
Angewandte Chemie International Edition,
February 1, 2023, 2023-Feb-01, 2023-02-00, 20230201, Letnik:
62, Številka:
6
Journal Article
Recenzirano
The oriented pore structure of wood endows it with a variety of outstanding properties, among which the low thermal conductivity has attracted researchers to develop wood‐like aerogels as excellent ...thermal insulation materials. However, the increasing demands of environmental protection have put forward new and strict requirements for the sustainability of aerogels. Here, we report an all‐natural wood‐inspired aerogel consisting of all‐natural ingredients and develop a method to activate the surface‐inert wood particles to construct the aerogel. The obtained wood‐inspired aerogel has channel structure similar to that of natural wood, endowing it with superior thermal insulation properties to most existing commercial sponges. In addition, remarkable fire retardancy and complete biodegradability are integrated. With the above outstanding performances, this sustainable wood‐inspired aerogel will be an ideal substitute for the existing commercial thermal insulation materials.
An interesting surface nanocrystallization method was developed to make the surface‐inert and weakly interacting wood particles better assemble to construct the aerogel. This bottom‐up method allows the preparation of large‐size composite aerogels. The wood‐inspired oriented channel structure endows the obtained aerogel with superior thermal insulation properties to natural wood and most existing commercial sponges.
By leveraging the ability of Shewanella oneidensis MR‐1 (S. oneidensis MR‐1) to anaerobically catabolize lactate through the transfer of electrons to metal minerals for respiration, a lactate‐fueled ...biohybrid (Bac@MnO2) was constructed by modifying manganese dioxide (MnO2) nanoflowers on the S. oneidensis MR‐1 surface. The biohybrid Bac@MnO2 uses decorated MnO2 nanoflowers as electron receptor and the tumor metabolite lactate as electron donor to make a complete bacterial respiration pathway at the tumor sites, which results in the continuous catabolism of intercellular lactate. Additionally, decorated MnO2 nanoflowers can also catalyze the conversion of endogenous hydrogen peroxide (H2O2) into generate oxygen (O2), which could prevent lactate production by downregulating hypoxia‐inducible factor‐1α (HIF‐1α) expression. As lactate plays a critical role in tumor development, the biohybrid Bac@MnO2 could significantly inhibit tumor progression by coupling bacteria respiration with tumor metabolism.
MnO2 nanoflowers were modified on the cell surface of electrochemically active bacteria, S. oneidensis MR‐1. The biohybrids, which couple bacterial respiration with tumor metabolism, can catabolize intercellular lactate and prevent intracellular lactate production in the tumor, thereby inducing significant tumor inhibition.
Widely used disposable plastic tableware is usually buried or directly discharged into the natural environment after using, which poses potential threats to the natural environment and human health. ...To solve this problem, nondegradable plastic tableware needs to be replaced by tableware composed of biodegradable structural materials with both food safety and the excellent mechanical and thermal properties. Here, a food‐safe sargassum cellulose nanofiber (SCNF) is extracted from common seaweed in an efficient and low energy consuming way under mild reaction conditions. Then, by assembling the SCNF into a dense bulk material, a strong sargassum cellulose nanofiber structural material (SCNSM) with high strength (283 MPa) and high thermal stability (>160 °C) can be prepared. The SCNSM also possesses good machinability, which can be processed into tableware with different shapes, e.g., knives and forks. The overall performance of the SCNSM‐based tableware is better than commercial plastic, wood‐based, and poly(lactic acid) tableware, which shows great application potential in the tableware field.
A food‐safe sargassum cellulose nanofiber (SCNF) is extracted through an efficient and low energy consuming way. Then, by assembling the SCNF into a dense bulk material, a strong structural material can be prepared. It possesses good machinability, which can be processed into tableware with better overall performance than that of commercial tableware, showing great application potential in the tableware field.
Despite the extraordinary X‐ray scintillation performance of three‐dimensional (3D) lead perovskite nanocrystals (PNCs), the serious biotoxicity of Pb2+ and luminescent instability in water remain ...insurmountable obstacles for their applications in medical imaging. To address these drawbacks, herein, the study demonstrates one new lead‐free zero‐dimensional (0D) hybrid cuprous halide of single‐crystalline BzTPP2Cu2I4 (BzTPP = Benzyltriphenylphosphonium) as a satisfactory X‐ray scintillator. BzTPP2Cu2I4 displays broadband yellowish‐green light emission with a high photoluminescent quantum yield (PLQY) of 44.2% and large Stokes shift of 167 nm upon UV light excitation. High PLQY and negligible self‐absorption enable BzTPP2Cu2I4 to display impressive scintillation performance excited by X‐ray with a light yield of 27 706 photons MeV‐1 and low detection limit of 0.352 µGy s−1, surpassing typical 3D PNCs. More importantly, BzTPP2Cu2I4 represents extraordinary structural and luminescent stability in water for at least one month. The excellent and stable radioluminescence performance as well as solution growth method ensure a BzTPP2Cu2I4‐based screen for fine‐resolution X‐ray imaging with potential in radiography and inspection. This work highlights the multiple merits of low‐toxicity and cost, high light yield, and long‐term water‐stability of 0D hybrid cuprous halides as highly desirable X‐ray scintillators.
The multiple merits of low toxicity and cost, high light yield, and long‐term water‐stability of 0D hybrid cuprous halide as a highly desirable light emitter and X‐ray scintillator are highlighted.
Room‐temperature phosphorescence (RTP) polymers, whose emission can persist for a long period after photoexcitation, are of great importance for practical applications. Herein, dynamic covalent ...boronic ester linkages with internal B−N coordination are incorporated into a commercial epoxy matrix. The reversible dissociation of B−N bonds upon loading provides an efficient energy dissipation pathway for the epoxy network, while the rigid epoxy matrix can inhibit the quenching of triplet excitons in boronic esters. The obtained polymers exhibit enhanced mechanical toughness (12.26 MJ m−3), ultralong RTP (τ=540.4 ms), and shape memory behavior. Notably, there is no apparent decrease in the RTP property upon prolonged immersion in various solvents because the networks are robust. Moreover, the dynamic bonds endow the polymers with superior reprocessablity and recyclability. These novel properties have led to their potential application for information encryption and anti‐counterfeiting.
Incorporating dynamic covalent boronic ester linkages with internal B−N coordination into a commercial epoxy matrix has led to the fabrication of high‐performance polymer‐based materials with ultralong room‐temperature phosphorescence. The polymers show excellent mechanical properties, environmental stability, shape memory, and recyclability, which could be useful for anticounterfeiting, data encryption, and information editing applications.
The widespread use of disposable plastic straws cause serious environmental problems and poses potential threats to human health, while paper straws, their most used alternatives, are not so ...satisfactory due to poor mechanical performance and unpleasant user experience. Here, a new kind of edible and microplastic‐free straw made from bacterial cellulose (BC) by biosynthesis is reported. Through the alginate coating, this BC‐based straw achieves better mechanical performance than paper straws and avoids additional adhesives. Owing to the 3D nanofiber network and strong interlayer connection, the comprehensive performance of this BC‐based straw surpasses that of commercially available counterparts, satisfying the requirements for practical use. Of particular note, the edible character provides a better user experience and a new end‐of‐life option for the straws, making the BC‐based straw a healthier and more eco‐friendly substitute for plastic straws.
A sustainable, microplastic‐free, ultrastrong, and edible straw is fabricated through biosynthesis. This bacterial cellulose‐based straw demonstrates great sustainability and excellent mechanical performance, representing an ideal substitute for plastic straws and a powerful competitor for paper straws. The 3D network of bacterial cellulose endows the straw with the ability to carry functional substances like flavor molecules, providing a better user experience.
The issue of accurately distinguishing and selectively powering multiple closely spaced devices is challenging but vital for wireless power transfer (WPT). In this article, a continuous-wave ...time-reversal selective radiative wireless power transfer (CWTR-SRWPT) method based on a multipoint focusing idea is proposed. With the proposed method, we realize a selective radiative WPT prototype system, which can arbitrarily select multiple devices spaced at a diffraction limited distance and power them simultaneously. The accurate positioning and high-precision spatial selection of the closely spaced energy-dissipated devices are achieved by the multipoint focusing field (MPFF) without any auxiliary positioning equipment. The MPFF is produced by a set of weight-optimized single-point focusing fields that are generated by the fundamental time-reversal technique. Theoretical analysis and full-wave simulations to the performances of the CWTR-SRWPT system are presented. The experimental demonstrations of selectively powering multiple LEDs are also conducted. The results indicate that the proposed method exhibits exciting performances of high-precision selectivity, accurate positioning, and satisfactory over-the-air efficiency. It demonstrates potential applications in selectively powering the wireless sensors distributed densely in future intelligent factories.
Abstract
Using the ERA‐5 reanalysis datasets, NCEP/NCAR sea ice concentration (SIC) and observed winter surface wind speed (WSWS) in northwest China during 1979–2020, this study examined the regime ...shift of the leading mode of observed WSWS in northwest China and investigated its possible link with the winter Barents–Kara Sea (BKS) SIC. The leading mode of observed WSWS in northwest China showed negative anomalies in southern and northeastern Xinjiang, Gansu, western and northern Shaanxi Provinces, and positive anomalies in northwestern and middle Xinjiang, Qinghai and Ningxia Provinces. The signs of WSWS in the leading mode is generally opposite to their trends during 1979–2020. Leading principal component (PC1) of observed WSWS in northwest China underwent an obvious decreasing regime shift in 2003/04, as well as the winter BKS SIC. There are significant correlations between PC1 and BKS SIC on both interdecadal and interannual timescales. Decadal decrease of BKS SIC is accompanied with a positive phase of Scandinavia pattern (SP) with positive anomalies of 500‐hPa geopotential height over subtropical North Atlantic, Arctic‐Ural region and southern Asia, and negative anomalies over northern North Atlantic‐West Europe and Siberia regions. BKS SIC and SP significantly influenced the Northern China Wind Index (NCWI) at 200 hPa on interdecadal timescale, which was related to the PC1 on both interdecadal and interannual timescales after removing the signal of Arctic Oscillation. Meridional configuration of Siberian cyclonic anomaly and southern Asian anticyclonic anomaly associated with the winter BKS SIC could enhance the intensity of NCWI, which favoured the increase of observed WSWS in northwest China and thereby may contribute to the regime shift in 2003/04 of the leading mode. However, there were still some stations showing decreasing regime shift, which mainly located at the region of steeping terrain. These decreasing changes of WSWS may be related to circumfluence effect of terrain, urbanization and local microclimate, and these reasons still need further detailed study.
