The past few decades have witnessed an evolution of nanomedicine from biologically inert entities to more smart systems, aimed at advancing in vivo functionality. However, we should recognize that ...most systems still rely on reasonable explanationincluding some over-explanationrather than definitive evidence, which is a watershed radically determining the speed and extent of advancing nanomedicine. Probing nano–bio interactions and desirable functionality at the tissue, cellular, and molecular levels is most frequently overlooked. Progress toward answering these questions will provide instructive insight guiding more effective chemo-physical strategies. Thus, in the next generation, we argue that much effort should be made to provide definitive evidence for proof-of-mechanism, in lieu of creating many new and complicated systems for similar proof-of-concept.
Sub‐5 nm metal nanogaps have attracted widespread attention in physics, chemistry, material sciences, and biology due to their physical properties, including great plasmon‐enhanced effects in ...light–matter interactions and charge tunneling, Coulomb blockade, and the Kondo effect under an electrical stimulus. These properties especially meet the needs of many cutting‐edge devices, such as sensing, optical, molecular, and electronic devices. However, fabricating sub‐5 nm nanogaps is still challenging at the present, and scaled and reliable fabrication, improved addressability, and multifunction integration are desired for further applications in commercial devices. The aim of this work is to provide a comprehensive overview of sub‐5 nm nanogaps and to present recent advancements in metal nanogaps, including their physical properties, fabrication methods, and device applications, with the ultimate aim to further inspire scientists and engineers in their research.
Sub‐5 nm metal nanogaps have attracted widespread attention in physics, chemistry, material sciences, and biology due to their physical properties. However, fabricating sub‐5 nm nanogaps is still challenging, impeding their further applications in commercial devices. This work aims to provide a comprehensive overview and recent advancements in sub‐5 nm metal nanogaps, including their physical properties, fabrication methods, and device applications.
Using NVivo12plus software, this study constructs a generation model of the policy implementation environment in China's grassroots digital construction by examining the data from interviews with 37 ...Chinese grassroots civil servants as its research object. At the same time, with the help of the csQCA method and on the basis of rooted coding, using Tosmana software, the model validation and model expansion of 37 cases were carried out. This study shows that the main components of the policy implementation environment in China's grassroots digital construction include five main dimensions: cognitive, emotional, behavioral, normative and control. At the initial stage of China's grassroots digital construction, the cognitive environment dimension is the most critical link in the environmental governance of policy implementation. The cognitive and normative environments dominate the effect pattern of China's grassroots digital policy implementation. There are six types of motivation patterns for the environmental effect of the implementation of grassroots digital policy: know-doing-norm, cognitive-dominant, know-doing-control, emotion-control, behavior-lacking and regulation-dominant types. Based on the above analysis, there are three main policy suggestions to promote the generation of a productive policy implementation environment and positive policy effects in China's digital construction: "degree", "force" and "sense". These suggestions include strengthening the top-level design, improving the integration and cooperation degree of the environment, taking the root at the grassroots level to improve the adaptability of the environment, as well as increasing publicity and promotion to improve the sense of environmental experience.
Therapeutic nanoreactors have been proposed to treat cancers through in situ transformation of low-toxicity prodrugs into toxic therapeutics in the body. However, the in vivo applications are limited ...by low tissue-specificity and different tissue distributions between sequentially injected nanoreactors and prodrugs. Herein, we construct a block copolymer prodrug-based polymersome nanoreactor that can achieve novel orchestrated oxidation/chemotherapy of cancer via specific activation at tumor sites. The block copolymers composed of poly(ethylene glycol) (PEG) and copolymerized monomers of camptothecin (CPT) and piperidine-modified methacrylate P(CPTMA-co-PEMA) were optimized to self-assemble into polymersomes in aqueous solution for encapsulation of glucose oxidase (GOD) to obtain GOD-loaded polymersome nanoreactors (GOD@PCPT-NR). GOD@PCPT-NR maintained inactive in normal tissues upon systemic administration. After deposition in tumor tissues, tumor acidity-triggered protonation of PPEMA segments resulted in high permeability of the polymersome membranes and oxidation reaction of diffused glucose and O2 under the catalysis of GOD. The activation of the reaction generated H2O2, improving the oxidative stress in tumors. Simultaneously, a high level of H2O2 further activated PCPTMA prodrugs, releasing active CPT drugs. High tumor oxidative stress and released CPT drugs synergistically killed cancer cells and suppressed tumor growth via oxidation/chemotherapy. Our study provides a new strategy for engineering therapeutic nanoreactors in an orchestrated fashion for cancer therapy.
Abstract
Excellent ductility is crucial not only for shaping but also for strengthening metals and alloys. The ever most widely used eutectic alloys are suffering from the limited ductility and ...losing competitiveness among advanced structural materials. Here we report a distinctive concept of phase-selective recrystallization to overcome this challenge for eutectic alloys by triggering the strain hardening capacity of the duplex phases completely. We manipulate the strain partitioning behavior of the two phases in a eutectic high-entropy alloy (EHEA) to obtain the phase-selectively recrystallized microstructure with a fully recrystallized soft phase embedded in the skeleton of a hard phase. The resulting microstructure fully releases the strain hardening capacity in EHEA by eliminating the weak boundaries. Our phase-selectively recrystallized EHEA achieves a high ductility of ∼35% uniform elongation with true stress of ∼2 GPa. This concept is universal for various duplex alloys with soft and hard phases and opens new frontiers for traditional eutectic alloys as high-strength metallic materials.
A porous MoO2 nanosheet as an active and stable bifunctional electrocatalyst for overall water splitting, is presented. It needs a cell voltage of only about 1.53 V to achieve a current density of 10 ...mA cm−2 and maintains its activity for at least 24 h in a two‐electrode configuration.
Conductive hydrogels have become one of the most promising materials for skin-like sensors because of their excellent biocompatibility and mechanical flexibility. However, the limited stretchability, ...low toughness, and fatigue resistance lead to a narrow sensing region and insufficient durability of the hydrogel-based sensors. In this work, an extremely stretchable, highly tough, and anti-fatigue conductive nanocomposite hydrogel is prepared by integrating hydrophobic carbon nanotubes (CNTs) into hydrophobically associated polyacrylamide (HAPAAm) hydrogel. In this conductive hydrogel, amphiphilic sodium dodecyl sulfate was used to ensure uniform dispersion of CNTs in the hydrogel network, and hydrophobic interactions between the hydrogel matrix and the CNT surface formed, greatly improving the mechanical properties of the hydrogel. The obtained CNTs/HAPAAm hydrogel showed excellent stretchability (ca. 3000%), toughness (3.42 MJ m–3), and great anti-fatigue property. Moreover, it exhibits both high tensile strain sensitivity in the wide strain ranges (gauge factor = 4.32, up to 1000%) and high linear sensitivity (0.127 kPa–1) in a large-pressure region within 0–50 kPa. The CNTs/HAPAAm hydrogel-based sensors can sensitively and stably detect full-range human activities (e.g., elbow rotation, finger bending, swallowing motion, and pronouncing) and handwriting, demonstrating the CNTs/HAPAAm hydrogel’s potential as the wearable strain and pressure sensors for flexible devices.
In this study, high solid loading and low viscosity cordierite slurries are successfully developed for the first time for photopolymerization-based additive manufacturing. The processability of the ...slurries is mainly determined by their rheological properties and photocuring parameters. The slurry preparation involves the orthogonal optimization of compositions in order to achieve suitable viscosity, stability and homogeneity. The photocuring parameters of the as-prepared slurries, including penetration depth Dp and critical exposure Ec, are also determined experimentally. Results show that viscosity increases with reduction in particle size. A higher solid-volume fraction also results in an exponential growth in viscosity. As for the dispersant amount, a concentration of 5 wt% leads to the lowest viscosity. Particle size also play an important role in the solid loading capacity of the slurries, as results suggest that smaller particles improve performance. In terms of the photocuring behaviors, the addition of 2 wt% photoinitiator generates an optimal curing process. 40 vol% solid loading leads to the thickest curing depth for all slurries with different types of particle sizes. Finally, a cordierite part with a complex hollow structure and a fine resolution is successfully fabricated. The present study offers a material basis for the polymerization-based 3D printing of porous cordierite structures.
A Rosenbrock artificial bee colony algorithm (RABC) that combines Rosenbrock’s rotational direction method with an artificial bee colony algorithm (ABC) is proposed for accurate numerical ...optimization. There are two alternative phases of RABC: the exploration phase realized by ABC and the exploitation phase completed by the rotational direction method. The proposed algorithm was tested on a comprehensive set of complex benchmark problems, encompassing a wide range of dimensionality, and it was also compared with several algorithms. Numerical results show that the new algorithm is promising in terms of convergence speed, success rate, and accuracy. The proposed RABC is also capable of keeping up with the direction changes in the problems.
Abstract
Optical metasurfaces with high quality factors (Q-factors) of chiral resonances can boost substantially light-matter interaction for various applications of chiral response in ultrathin, ...active, and nonlinear metadevices. However, current approaches lack the flexibility to enhance and tune the chirality and Q-factor simultaneously. Here, we suggest a design of chiral metasurface supporting bound state in the continuum (BIC) and demonstrate experimentally chiroptical responses with ultra-high Q-factors and near-perfect circular dichroism (CD = 0.93) at optical frequencies. We employ the symmetry-reduced meta-atoms with high birefringence supporting winding elliptical eigenstate polarizations with opposite helicity. It provides a convenient way for achieving the maximal planar chirality tuned by either breaking in-plane structure symmetry or changing illumination angle. Beyond linear CD, we also achieved strong near-field enhancement CD and near-unitary nonlinear CD in the same planar chiral metasurface design with circular eigen-polarization. Sharply resonant chirality realized in planar metasurfaces promises various practical applications including chiral lasers and chiral nonlinear filters.
