Recent Advances in Flexible CNC-Based Chiral Nematic Film Materials.

Cellulose nanocrystal (CNC) is a renewable resource derived from lignocellulosic materials, known for its optical permeability, biocompatibility, and unique self-assembly properties. Recent years have seen great progresses in cellulose nanocrystal-based chiral photonic materials. However, due to its inherent brittleness, cellulose nanocrystal shows limitations in the fields of flexible materials, optical sensors and food freshness testing. In order to solve the above limitations, attempts have been made to improve the flexibility of cellulose nanocrystal materials without destroying their structural color. Despite these progresses, a systematic review on them is lacking. This review aims to fill this gap by providing an overview of the main strategies and the latest research findings on the flexibilization of cellulose nanocrystal-based chiral nematic film materials (FCNM). Specifically, typical substances and methods used for their preparation are summarized. Moreover, different kinds of cellulose nanocrystal-based composites are compared in terms of flexibility. Finally, potential applications and future challenges of flexible cellulose nanocrystal-based chiral nematic materials are discussed, inspiring further research in this field.

Correction: Recent advances in self-healing polyurethane based on dynamic covalent bonds combined with other self-healing methods.

Correction for 'Recent advances in self-healing polyurethane based on dynamic covalent bonds combined with other self-healing methods' by Ze-Wei An et al., Nanoscale, 2023, 15, 6505-6520, https://doi.org/10.1039/D2NR07110J.

Self-Healable, Solvent Response Cellulose Nanocrystal/Waterborne Polyurethane Nanocomposites with Encryption Capability.

Cellulose nanocrystal (CNC)-based chiral nematic structure is widely used in stimulus response and sensing. A popular area of research is enhancing the mechanical characteristics and environmental adaptability of chiral nematic materials. In this paper, a flexible photonic film with self-healing ability (FPFS) was prepared by combining waterborne polyurethane containing dynamic covalent disulfide bonds (SSWPU) with CNC. The results found that the FPFS showed excellent toughness under the action of stretching, bending, twisting, and folding. The FPFS exhibited an amazing self-healing efficiency, which can be self-healed within 2 h at room temperature. Moreover, the FPFS could respond immediately and produce reversible color change when it was soaked in typical solvents. In addition, when ethanol was used as ink to paint on the FPFS, a visible pattern only under polarized light was formed. This study offers fresh perspectives in the areas of self-healing, biological anticounterfeiting, solvent response, and flexible photonic materials.

Recent advances in self-healing polyurethane based on dynamic covalent bonds combined with other self-healing methods.

To meet more application requirements, improving mechanical properties and self-healing efficiency has become the focus of current research on self-healing PU. The competitive relationship between self-healing ability and mechanical properties cannot be avoided by a single self-healing method. To address this problem, a growing number of studies have combined dynamic covalent bonding with other self-healing methods to construct the PU structure. This review summarizes recent studies on PU materials that combine typical dynamic covalent bonds with other self-healing methods. It mainly includes four parts: hydrogen bonding, metal coordination bonding, nanofillers combined with dynamic covalent bonding and multiple dynamic covalent bond bonding. The advantages and disadvantages of different self-healing methods and their significant role in improving self-healing ability and mechanical properties in PU networks are analyzed. At the same time, the possible challenges and research directions of self-healing PU materials in the future are discussed.

Porous cellulose composite aerogel films with super piezoelectric properties for energy harvesting.

The piezoelectric effect is one of the most promising electromechanical coupling processes for mechanical energy conversion and energy harvesting. However, natural polymer based piezoelectric materials are of poor piezoelectric performance. we developed flexible porous piezoelectric aerogel films based on TEMPO-oxidized cellulose nanofibrils (TOCN) and MoS2 nanosheets. Those aerogel films possessed large specific surface areas and abundant mesopores. Moreover, they exhibited very good piezoelectric properties when a field strength of 20 MV/m was used to polarize MoS2 nanosheets and air in the mesopores. When assembled to piezoelectric nanogenerators (PENGs), a TOCN/MoS2 aerogel film PENG containing 6 wt% of MoS2 exhibited the best output performance. It generated an open circuit voltage of 42 V and a short-circuit current of 1.1 µA, a maximum area power density of 1.29 µW/cm2 and a maximum volume power density of 0.143 µW/cm3. These features enable them to be promising piezoelectric materials for energy harvesting.

Recent advances in superhydrophobic polyurethane: preparations and applications.

Even though polyurethane (PU) has been widely applied, its superhydrophobicity is inadequate for certain applications. As such, the development of superhydrophobic polyurethane (SHPU) has recently attracted significant attention, with numerous motivating reports in recent years. However, a comprehensive review that summarizes these state-of-the-art developments remains lacking. Thus, this review aims to fill up this gap by reviewing the recent preparation methods for SHPU based on superhydrophobic theories and principles. Three main types of methods used in promoting the hydrophobicity of PU are emphasized in this review; (1) incorporation of silicide or fluoride to lower the surface energy, (2) creation of micro/nano-scale rough surfaces by electrospinning or grafting of nanoparticles, and (3) integrating the earlier two methods to develop a synergistic approach. Furthermore, this review also discussed the various applications of SHPU in oil spill treatment, protective coating, self-healing materials and sensors.

Design of a Superhydrophobic Strain Sensor with a Multilayer Structure for Human Motion Monitoring.

A flexible strain sensor is of significant importance in wearable electronics since it can help monitor the physical signals from the human body. Among various strain sensors, the polyurethane (PU)-based ones have received widespread attention owing to their excellent toughness, large working range, and nice gas permeability. However, the hydrophobicity of these sensors is not good enough, which may affect their use life and sensitivity. In this work, a high-performance strain sensor composed of PU, reduced graphene oxide (rGO), polydopamine (PDA), and 1H,1H,2H,2H-perfluorodecane-thiol (PFDT) was designed and prepared. The results revealed that this PU/rGO/PDA/PFDT device possessed good superhydrophobicity with a water contact angle of 153.3°, a wide working strain range of 590%, and an outstanding gauge factor as high as 221 simultaneously. Because of these above advantages, the sensor worked effectively in detecting both subtle and large human movements (such as joint motion, finger motion, and vocal cord vibration) even in a high humidity environment. This strain sensor with high sensitivity, wide working range, and suitable modulus may have great potential in the field of flexible and wearable electronics in the near future.

Effect of Stretching on Crystalline Structure, Ferroelectric and Piezoelectric Properties of Solution-Cast Nylon-11 Films.

Compared to polyvinylidene fluoride (PVDF) and its copolymers, castor-oil-derived nylon-11 has been less explored over the past decades, despite its excellent piezoelectric properties at elevated temperatures. To utilize nylon-11 for future sensor or vibrational energy harvesting devices, it is important to control the formation of the electroactive δ' crystal phase. In this work, nylon-11 films were first fabricated by solution-casting and were then uniaxially stretched at different stretching ratios (SR) and temperatures (Ts) to obtain a series of stretched films. The combination of two-dimensional wide-angle X-ray diffraction (2D-WAXD) and differential scanning calorimetry (DSC) techniques showed that the fraction of the δ' crystal phase increased with the stretching ratio and acquired a maximum at a Ts of 80 °C. Further, it was found that the ferroelectric and piezoelectric properties of the fabricated nylon-11 films could be correlated well with their crystalline structure. Consequently, the stretched nylon-11 film stretched at an SR of 300% and a Ts of 80 °C showed maximum remanent polarization and a remarkable piezoelectric coefficient of 7.2 pC/N. A simple piezoelectric device with such a nylon-11 film was made into a simple piezoelectric device, which could generate an output voltage of 1.5 V and a current of 11 nA, respectively.

Necklace-like ferroferric oxide (Fe3O4) nanoparticle/carbon nanofibril aerogels with enhanced lithium storage by carbonization of ferric alginate.

Theoretically, transition metal oxide/carbon nanofibril aerogels are promising candidates for lithium-ion battery anode materials as they combine the high stability and electrical conductivity of the carbon matrix and the high theoretical specific capacity of transition metal oxide (TMO). However, challenges still exist to embed TMO nanoparticles into thin carbon nanofibril absolutely and tightly, limiting further improvements in electrochemical performances of the composites. Herein, necklace-like Fe3O4/carbon nanofibril aerogel (Fe3O4/CNF) was constructed by crosslinking alginate with Fe3+, followed by carbonization of the obtained ferric alginate aerogel. Based on an "egg-box" helical structure resulting from strong coordination between the Fe3+ and the carboxylate groups of alginate, three-dimensional interconnected carbon aerogel was facilely fabricated with Fe3O4 nanoparticles (~11 nm in diameter) firmly embedded in ultrafine carbon nanofibrils (~18 nm in diameter), exhibiting a special necklace-like structure. Consequently, the composite exhibits a high reversible capacity and stability of 1176 mAh g-1 over 200 cycles at 1 A g-1 and a high rate performance of 615 mAh g-1 at 4 A g-1. These Fe3O4/CNF aerogels may have potential applications for enhanced lithium storage of electrochemical devices.

[Sustainability science revisited: Recent advances and new opportunities]. / 再论可持续性科学: 新形势与新机遇.

During the past decade, sustainability science has rapidly developed into a globally well-recognized and important new science of the 21st century. However, sustainability science has not received much attention from scientists and practitioners in China where sustainable development and ecological civilization have been prominent themes. To promote the development of sustainability science in China, Wu, et al. (2014) published the first in-depth review on the subject in Chinese, entitled What is sustainability science? Here, we revisit the question, and discuss the relationship between sustainability science and sustainable development research, the scientific paradigm and the core research questions of sustainability science. Our review of the recent advances in this field reveals contrasting trends for the world versus China. On the one hand, the world is witnessing sustainability science maturing with global momentum to systematically advance sustainability research and education. On the other hand, China greatly lags behind developed countries and South Africa, albeit the great deal of new passion and desire for sustainable development. To promote the science and practice of sustainability in China, we propose a trinity strategy: 1) bringing in from the global community to guide Chinese practices in sustainable development; 2) reaching out to the global community to share Chinese wisdom of sustainable development; and 3) integrating traditional Chinese philosophy with western science to lead the development of sustainability science.

IL-37 attenuates allergic process via STAT6/STAT3 pathways in murine allergic rhinitis.

Allergic rhinitis (AR) is a common upper airway allergic disease caused by allergens triggering a type 2 immune response. The imbalance of CD4+ T cell subsets is the essential immunological feature of AR, which is mainly characterized by the predominance of T helper (Th) 2 cells. Recent studies indicated that the anti-inflammatory factor interleukin (IL)-37 is involved in the immune regulation of AR. However, the mechanism of IL-37 acts on AR has not been fully elucidated. Thus, we sought to assess the protective role of IL-37 in AR and further explore the possible mechanism. An ovalbumin (OVA)-induced AR murine model was established. After IL-37 treatment, the allergic symptoms (sneezes and nasal rubbings), nasal mucosal infiltration with eosinophils, and serum IgE production were found significantly attenuated. For CD4+ T cell subsets, the proliferation and differentiation of Th2 and Th17 cells were restrained. The relevant effector cytokines of IL-4, IL-5, IL-6, and IL-17a protein expression and transcription factors GATA3 and RORγt mRNA levels were obviously decreased. However, IL-37 had no significant effect on Th1 and Treg response including in IFN-γ, IL-10, T-bet, and Foxp3 expression. Furthermore, IL-37 was found down-regulated the STAT6, STAT3, phospho-STAT6, and phospho-STAT3 expression. In conclusion, IL-37 alleviates allergic inflammation in AR possibly through repressing STAT6 and STAT3 signaling pathways.

Comparison of the value of superficial mark guided localization and hook-wire guided localization techniques for non-palpable breast microcalcifications: A retrospective clinical research.

AIM: The present study compares the effect and accuracy of the superficial mark guided localization (SGL) and hook-wire guided localization (WGL) techniques for non-palpable breast microcalcifications. METHODS: This retrospective study was conducted to compare SGL and WGL techniques. These techniques were performed on 51 patients with non-palpable breast microcalcifications from January 2015 to May 2016. RESULTS: Among these 51 patients, 25 (49.01%) patients were subjected to WGL and 26 patients (50.99%) were subjected to SGL. The SGL technique had a higher rate of malignant cancer detection (WGL = 12.0% and SGL = 23.0%). Furthermore, no significant differences were found with regard to average age, the rate of a second excision and the diameter of the excised tissue. Moreover, no complications were observed in the SGL group, while four (16.0%) patients in the WGL group experienced problems. CONCLUSION: The SGL technique is as accurate as the WGL technique. Furthermore, the procedure has advantages of being less expensive and causing less complications.

The airway inflammation induced by nasal inoculation of PM2.5 and the treatment of bacterial lysates in rats.

Particulate matter (PM) is one of the most important environmental issues in China. This study aimed to explore the correlation between PM2.5 and airway inflammation in healthy rats. The PM2.5 group was given an intranasal instillation of PM2.5 suspension on 15 consecutive days, and each received oral saline from day 16 to 90. The BV intervention group was treated as the PM2.5 exposure group, except that BV instead of saline was given daily. A histopathologic examination was performed to evaluate the airway inflammation. The prevalence and function of Th1/Th2/Treg/Th17 cells were detected by flow cytometry and ELISA. The expression of AhR was detected by western blot and real-time PCR. We found that epithelial damage and increased infiltration of inflammatory cell were present in the airways after PM2.5 exposure; there was an immune imbalance of Th cells in the PM2.5 group; the expression of AhR was increased in the airways after PM2.5 exposure. In the PM2.5 + BV group, we demonstrated alleviated immune imbalance and reduced inflammatory cell infiltration in the airways. Our study showed that exposure to PM2.5 induced airway inflammation. The imbalance of Th1/Th2/Treg/Th17 in PM2.5-induced airway inflammation might be associated with activation of the AhR pathway. Oral BV reduces PM2.5-induced airway inflammation and regulates systemic immune responses in rats.

Increased expression of IL-1R8 and a possible immunomodulatory role of its ligand IL-37 in allergic rhinitis patients.

Allergic rhinitis (AR) is a chronic inflammatory airway disease that is caused by an abnormal T cell response. T helper (Th)-17 cells and Th2 cells are the CD4+ T cell subsets implicated in the pathogenesis of AR. The suppression of excessive responses of these Th17 and Th2 cells has been reported to be an effective therapeutic approach to treat AR patients, and continuous efforts are being undertaken to find new methods to modulate the function of these cells. Recent studies have shown that IL-1R8 and its ligand IL-37 negatively regulate the immune response. In this study, we investigated the immunomodulatory the roles of IL-37/IL-1R8 axis in AR patients. We found that IL-1R8 expression was very low on dendritic cells (DCs) and resting CD4+ T cells but increased strongly on CD4+ T cells following T cell activation. Furthermore, IL-1R8 expression on CD4+ T cells was markedly higher in AR patients than in healthy controls. The IL-1R8 ligand IL-37 could act on CD4+ T cells to inhibit IL-17 and IL-4 production but could not influence DC-induced IL-17- and IL-4-producing CD4+ T cell responses. Meanwhile, recombinant IL-37 (rIL-37) did not influence IL-6, IL-1ß, and IL-10 production by DCs and expression of co-stimulatory molecules (including CD80, CD40, CD86 and HLA-DR) in DCs. Thus, IL-37 may regulate aberrant T cell immune response of allergic rhinitis mainly through CD4+ T cells, not DCs. The immunomodulatory roles of the IL-37/IL-1R8 axis indicate the therapeutic potential of this axis in AR.

Decreased expression of interleukin­37 and its anti­inflammatory effect in allergic rhinitis.

Interleukin­37 (IL­37), a novel member of the IL­1 cytokine family has been identified as a natural suppressor of innate immunity and inflammatory responses. The present study aimed to determine the expression of IL­37 in peripheral blood mononuclear cells (PBMCs) from patients with allergic rhinitis (AR), and examine the possible immunosuppressive effect of IL­37 on inflammatory mediators and CD4+ T cells in the pathogenesis of AR. The expression levels of IL­37 were determined in PBMCs from 39 patients with AR and 43 controls using reverse transcription­quantitative polymerase chain reaction (RT­qPCR) analysis and flow cytometry. Cytokines in the supernatants of the PBMCs and CD4+ T cells, which were stimulated with lipopolysaccharide in the presence or absence of IL­37, were assayed using enzyme­linked immunosorbent assays and RT­qPCR analysis. The results showed that the patients with AR exhibited significantly decreased expression of IL­37, and increased expression levels of interleukin (IL)­1ß and IL­6 in PBMCs. Recombinant IL­37 (rIL­37) inhibited the production of IL­1p and IL­6, and enhanced the production of IL­27 in PBMCs from the patients with AR and the control individuals. rIL­37 also markedly decreased the expression of IL­17 by CD4+ T cells in the patients with AR and controls. These results suggested that IL­37 may be an important cytokine in the pathogenesis of AR. It may have a protective role in AR by inhibiting the production of proinflammatory cytokines and through suppressive regulation of the Th17 response.

Assessment of postsurgical outcomes between different implants in patients with empty nose syndrome: A meta-analysis.

Objectives The aim of this study was to evaluate the impact of surgery and different implant materials on subjective outcomes in patients with empty nose syndrome (ENS). Methods Postsurgical outcomes were assessed in a meta-analysis of patients with ENS who underwent treatment with different implants. Results We identified 122 relevant studies, and 6 were included in the meta-analysis (4 prospective trials and 2 randomized controlled trials). A significant difference was found between the preoperative and postoperative Sino-Nasal Outcome Test (SNOT) scores for different implants. With respect to implant materials, significant differences were observed between autografts/allografts (AG) and foreign material grafts (FGs). A subgroup analysis of different countries showed that more patients from China underwent surgical implant therapy than patients from other countries. Conclusions This meta-analysis suggests that surgery can improve the symptoms and SNOT scores of patients with ENS, AGs are more effective than FGs in patients with ENS, and that more patients from China undergo surgical implant therapy than patients from other countries.

Flexible Carbon Nanotube Modified Separator for High-Performance Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries have become promising candidates for electrical energy storage systems due to their high theoretical specific energy density, low cost and environmental friendliness. However, there are some technical obstacles of lithium-sulfur batteries to be addressed, such as the shuttle effect of polysulfides. Here, we introduced organically modified carbon nanotubes (CNTs) as a coating layer for the separator to optimize structure and enhance the performance of the Li-S battery. The results showed that the cell with a CNTs-coated separator exhibited an excellent cycling performance. Compared to the blank separator, the initial discharge capacity and the capacity after 100 cycles for the CNTs-coated separator was increased by 115% and 161%, respectively. Besides, according to the rate capability test cycling from 0.1C to 2C, the battery with a CNTs-coated separator still released a capacity amounting to 90.2% of the initial capacity, when the current density returned back to 0.1C. It is believed that the organically modified CNTs coating effectively suppresses the shuttle effect during the cycling. The employment of a CNTs-coated separator provides a promising approach for high-performance lithium-sulfur batteries.

Progress in bio-inspired sacrificial bonds in artificial polymeric materials.

Mimicking natural structures has been highly pursued in the fabrication of synthetic polymeric materials due to its potential in breaking the bottlenecks in mechanical properties and extending the applications of polymeric materials. Recently, it has been revealed that the energy dissipating mechanisms via sacrificial bonds are among the important factors which account for strong and tough attributes of natural materials. Great progress in synthesis of polymeric materials consisting of sacrificial bonds has been achieved. The present review aims at (1) summarizing progress in the mechanics and chemistry of sacrificial bond bearing polymers, (2) describing the mechanisms of sacrificial bonds in strengthening/toughening polymers based on studies by single-molecule force spectroscopy, chromophore incorporation and constitutive laws, (3) presenting synthesis methods for sacrificial bonding including dual-crosslink, dual/multiple-network, and sacrificial interfaces, (4) discussing the important advances in engineering sacrificial bonding into hydrogels, biomimetic structures and elastomers, and (5) suggesting future works on molecular simulation, viscoelasticity, construction of sacrificial interfaces and sacrificial bonds with high dissociative temperature. It is hoped that this review will provide guidance for further development of sacrificial bonding strategies in polymeric materials.

Preparation and Characterization of Polyurethanes with Cross-Linked Siloxane in the Side Chain by Sol-Gel Reactions.

A series of novel polyurethanes containing cross-linked siloxane in the side chain (SPU) were successfully synthesized through a sol-gel process. The SPU was composed of 0%-20% N-(n-butyl)-3-aminopropyltriethoxysilane (HDI-T) modified hexamethylene diisocynate homopolymer. The effects of HDI-T content on both the structure and properties of SPU were investigated by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), mechanical properties tests, gel content test, water contact angle measurement and water absorption test. FT-IR, XPS and XRD results confirmed the successful incorporation of HDI-T onto polyurethanes and the formation of Si-O-Si. The surface roughness and the Si content of SPU enhanced with the increase of HDI-T content. Both crystallization and melting temperature shifted to a lower point after the incorporation of HDI-T. The hydrophobicity, tensile strength, Young's modulus and pencil hardness overall increased with the increasing of HDI-T content, whereas the thermal stability and the elongation at break of SPU slightly decreased.

Effects of Poly(cyclohexanedimethylene terephthalate) on Microstructures, Crystallization Behavior and Properties of the Poly(ester ether) Elastomers.

To understand the role of molecular structure on the crystallization behavior of copolyester in thermoplastic poly(ether ester) elastomers (TPEEs), series of poly(butylene-co-1,4-cyclohexanedimethylene terephthalate) (P(BT-co-CT))-b-poly(tetramethylene glycol) (PTMG) are synthesized through molten polycondensation process. The effects of poly(cyclohexanedimethylene terephthalate) (PCT) content on the copolymer are investigated by Fourier transform infrared spectroscopy (FT-IR), ¹H and 13C nuclear magnetic resonance (NMR), gel permeation chromatographs (GPC), wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), mechanical, and visible light transmittance tests. FT-IR and NMR results confirm the incorporation of PCT onto the copolymer. WAXD and DSC indicate that the crystalline structure of the copolymers changed from α-PBT lattice to trans-PCT lattice when the molar fraction of PCT (MPCT) is above 30%, while both crystallization and melting temperatures reach the minima. An increase in MPCT led to an increase in the number sequence length of PCT, the thermal stability and the visible light transmittance of the copolymer, but to a slight decrease in tensile strength and elastic modulus.