Conductive hydrogels as flexible electronic devices, not only have unique attractions but also meet the basic need of mechanical flexibility and intelligent sensing. How to endow anisotropy and a ...wide application temperature range for traditional homogeneous conductive hydrogels and flexible sensors is still a challenge. Herein, a directional freezing method is used to prepare anisotropic MXene conductive hydrogels that are inspired by ordered structures of muscles. Due to the anisotropy of MXene conductive hydrogels, the mechanical properties and electrical conductivity are enhanced in specific directions. The hydrogels have a wide temperature resistance range of −36 to 25 °C through solvent substitution. Thus, the muscle‐inspired MXene conductive hydrogels with anisotropy and low‐temperature resistance can be used as wearable flexible sensors. The sensing signals are further displayed on the mobile phone as images through wireless technology, and images will change with the collected signals to achieve motion detection. Multiple flexible sensors are also assembled into a 3D sensor array for detecting the magnitude and spatial distribution of forces or strains. The MXene conductive hydrogels with ordered orientation and anisotropy are promising for flexible sensors, which have broad application prospects in human–machine interface compatibility and medical monitoring.
Inspired by the ordered structure of muscles, MXene conductive hydrogels are anisotropic and can be used as wearable flexible sensors. The conductive hydrogels have the advantages of wide temperature tolerance range, high sensitivity and good stability. The flexible sensors can achieve motion detection through wireless technology and can be assembled into 3D arrays.
Echinochloa crusgalli (L.) Beauv. (barnyard grass) is considered a noxious weed worldwide, and is the most pernicious weed decreasing rice yields in China. Recently, E. crusgalli has evolved ...quinclorac resistance, making it among the most serious herbicide resistant weeds in China. The present study explored differences in germination and growth between quinclorac-resistant and -susceptible E. crusgalli collected in Hunan Province. The order of the seven E. crusgalli biotypes assessed, from high to low quinclorac-resistance, was: quinclorac-resistant, Chunhua, Hanshou, Shimen, Hekou, Dingcheng, and quinclorac-susceptible. With an increased in the level of quinclorac-resistance, the germination rate, length of young shoots and roots, and fresh weight of E. crusgalli were all decreased compared with that in more susceptible biotypes. However, there were no significant differences between quinclorac-resistant and susceptible E. crusgalli biotypes without polyethylene glycol 6000 treatment. Drought had a more obvious effect on glutathione S-transferases (GST) activity, determined by spectrophotometric method, in quinclorac-resistant E. crusgalli. Higher resistance level biotypes showed greater activity, and when treated with polyethylene glycol 6000 for 3 days, all E. crusgalli biotypes showed the highest GST activity. This study demonstrated that as the level of quinclorac-resistance increased, the rate of seed germination decreased, while the growth of young buds, young roots, and fresh weight decreased. Increased quinclorac-resistance may be related to the increased metabolic activity of GST in E. crusgalli.
Fluorescent graphene-based materials, labelled as a sort of fluorescent carbon-based nanomaterial, have drawn increasing attention in recent years. When the size and structure of graphene were ...controlled properly, photoluminescence was induced in graphene, resulting in the so-called fluorescent graphene (FG). FG has a size-, defect-, and wavelength-dependent luminescence emission, which is similar to traditional semiconductor-based quantum dots. Moreover, with excellent chemical stability, fine biocompatibility, low toxicity, up-conversion emission, pH-sensitivity and resistance to photobleaching, FG promises to offer substantial applications in numerous areas: bioimaging, photovoltaics, sensors,
etc.
Currently, research works have allowed FG to be produced by many approaches ranging from simple oxidation of graphene to cutting carbon sources and organic synthesis from small molecules. In this Feature Article, we summarize the reported fluorescent graphenes, with emphasis on their category, properties, synthesis and applications. Meanwhile, we give a perspective on their subsequent developments and compare the features of FG and other fluorescent carbon-based materials.
A rising and interesting fluorescent nanomaterial, fluorescent graphene (FG), lights up the nano-world, which has significant meaning for theoretical study as well as practical applications.
Full‐thickness skin injuries have always been an intricate problem in clinical treatment. The application of biomaterials provides an artificial matrix for the recruitment of cells and deposition of ...extracellular matrix to accelerate wound healing. For the recovery of full‐thickness skin defects, the double cross‐linking of MgO‐catechol and Schiff's base bonds are used as part of the gel‐forming mechanism, and a bio‐multifunctional hydrogel (CCOD‐MgO) is prepared by adding MgO to catechol‐modified chitosan (CHI‐C) and oxidized dextran (ODex). The CCOD‐MgO demonstrates high tissue adhesion, excellent self‐repairing, hemostasis function, and low swelling rate. With the addition of MgO and catechol chelation, the adhesion strength of CCOD‐MgO is about 35 kpa, which is much greater than fibrin glue. Moreover, the CCOD‐MgO has better antibacterial properties than CHI‐C/ODex hydrogel (CCOD) due to the synergy of chitosan and MgO in vitro. Accordingly, the CCOD‐MgO can protect the wounds from infection and accelerate the healing speed of the epidermis in full‐thickness cutaneous defect and burn model in vivo. These results demonstrate that the CCOD‐MgO would be a promising therapeutic strategy in full‐thickness skin injuries for clinical therapies.
A multifunctional skin repair adhesive dressing is obtained by adding MgO to catechol‐modified chitosan and oxidized dextran. This hydrogel demonstrates high tissue adhesion, excellent self‐repairing, hemostasis function, low swelling rate, and anti‐infection ability, which can accelerate the healing speed of the skin in full‐thickness cutaneous defect and burn model in vivo.
At present, the actual mechanism of the photoluminescence (PL) of fluorescent carbon dots (CDs) is still an open debate among researchers. Because of the variety of CDs, it is highly important to ...summarize the PL mechanism for these kinds of carbon materials; doing so can guide the development of effective synthesis routes and novel applications. This review will focus on the PL mechanism of CDs. Three types of fluorescent CDs were involved: graphene quantum dots (GQDs), carbon nanodots (CNDs), and polymer dots (PDs). Four reasonable PL mechanisms have been confirmed: the quantum confinement effect or conjugated π-domains, which are determined by the carbon core; the surface state, which is determined by hybridization of the carbon backbone and the connected chemical groups; the molecule state, which is determined solely by the fluorescent molecules connected on the surface or interior of the CDs; and the crosslink-enhanced emission (CEE) effect. To give a thorough summary, the category and synthesis routes, as well as the chemical/physical properties for the CDs, are briefly introduced in advance.
A
bstract
We explore the possible low energy phases of the confining non-supersymmetric SU(5) chiral gauge theory with three generations of fermions in the (10+
5
¯
) representations. This theory has ...the same fermion and gauge matter content as the simplest Georgi-Glashow grand unified theory of the Standard Model and has an SU(3) × SU(3) × U(1) global symmetry. Using ’t Hooft anomaly matching, most attractive channel, and soft SUSY breaking approaches, we outline a number of possible consistent low energy vacua including one with a remnant SO(3) × U(1) symmetry that is analogous to the one-generation model. For the soft SUSY breaking approach, we find that as one extrapolates to large SUSY breaking to recover the original theory, a phase transition is possible. We show that such a phase transition is guaranteed if SUSY breaking is communicated via anomaly mediation.
2D halide perovskites have recently been recognized as a promising avenue in perovskite solar cells (PSCs) in terms of encouraging stability and defect passivation effect. However, the efficiency ...(less than 15%) of ultrastable 2D Ruddlesden–Popper PSCs still lag far behind their traditional 3D perovskite counterparts. Here, a rationally designed 2D‐3D perovskite stacking‐layered architecture by in situ growing 2D PEA2PbI4 capping layers on top of 3D perovskite film, which drastically improves the stability of PSCs without compromising their high performance, is reported. Such a 2D perovskite capping layer induces larger Fermi‐level splitting in the 2D‐3D perovskite film under light illumination, resulting in an enhanced open‐circuit voltage (Voc) and thus a higher efficiency of 18.51% in the 2D‐3D PSCs. Time‐resolved photoluminescence decay measurements indicate the facilitated hole extraction in the 2D‐3D stacking‐layered perovskite films, which is ascribed to the optimized energy band alignment and reduced nonradiative recombination at the subgap states. Benefiting from the high moisture resistivity as well as suppressed ion migration of the 2D perovskite, the 2D‐3D PSCs show significantly improved long‐term stability, retaining nearly 90% of the initial power conversion efficiency after 1000 h exposure in the ambient conditions with a high relative humidity level of 60 ± 10%.
2D perovskite capping layers are grown in situ on top of the 3D perovskite film, leading to an enhanced efficiency of 18.5% in the stacking‐layered 2D‐3D perovskite solar cells (PSCs). Moreover, the unencapsulated 2D‐3D PSCs show drastically improved long‐term stability, retaining nearly 90% of the original efficiency after 1000 h exposure in a highly humid environment.
A surface is said to be isotropic in wettability when the contact angles measured in all direction are identical. On the contrary, once a surface shows distinct contact angles in "specific" but not ...random directions, the surface is considered to show anisotropic wetting, accompanied by anisotropic droplet spreading (in cases with greater wetting) or anisotropic droplet movement (in cases with greater anti-wetting). Anisotropic wetting occurs when the liquid contact line encounters physical asymmetry or chemical heterogeneity present on a solid surface. In recent years, anisotropic wetting surfaces have attracted wide scientific attention for both fundamental research and practical applications. Controllable directional liquid transportation, as a promising and important form of intelligent liquid manipulation, plays an important role in lots of fields. In nature, anisotropic wettability has been observed on a variety of biological surfaces, such as rice leaves, butterfly wings, desert beetle elytra, spider silks, cactus spines, and
Nepenthes alata
peristomes. Inspired by biological surfaces with anisotropic wetting properties, researchers have made great progress in the design and fabrication of micro-/nanostructures with the desired anisotropic wettability. This review focuses on typical and recent advances in the areas of natural and artificial anisotropic wetting surfaces, mainly based on micro-/nanostructures, and on their preparation methods and applications in liquid transportation, microfluidics, fog harvesting, and oil-water separation. Furthermore, potential applications of anisotropic wetting micro-/nanostructures in microreactors, biomedical devices, and sensors are presented.
Recent advances in the development and application of novel anisotropic wetting interfacial phenomena through the use of unique micro-/nanostructures have been summarized.
The development of the complexity and connectivity of modern automobiles has caused a massive rise in the security risks of in-vehicle networks (IVNs). Nevertheless, existing IVN designs (e.g., ...controller area network) lack cybersecurity consideration. Intrusion detection, an effective method for defending against cyberattacks on IVNs while providing functional safety and real-time communication guarantees, aims to address this issue. Therefore, the necessity of its research has risen. In this paper, an IVN environment is introduced, and the constraints and characteristics of an intrusion detection system (IDS) design for IVNs are presented. A survey of the proposed IDS designs for the IVNs is conducted, and the corresponding drawbacks are highlighted. Various optimization objectives are considered and comprehensively compared. Lastly, the trend, open issues, and emerging research directions are described.
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