The current study investigates the role of the tier‐one cities of China in affecting regional disparities within and across its five mega‐city clusters, through the lens of housing market. For that ...purpose, an equilibrating ripple effect is differentiated from a disturbing information cascade effect. Evidence suggests that a modest slow‐moving equilibrating force originated from Hong Kong has flowed across all tier‐one and most tier‐two cities in the mainland, indicating a narrowing of regional inequalities between Hong Kong and the mainland cities. On the other hand, a powerful disturbing force emanated from Beijing has affected all other cities, widening the inequality gap in between. The impulse response functions further suggest that this disturbing force has a permanent impact on regional disparity.
Mobile micro‐ and nanorobots are proposed for future biomedical applications, such as diagnostics and targeted delivery. For their translation to clinical practice, biocompatibility and ...biodegradability of micro‐ and nanorobots are required aspects. The fabrication of small‐scale robots with non‐cytotoxic biodegradable soft components will allow for enhanced device assimilation, optimal tissue interaction and minimized immune reactions. The 3D microfabrication of biodegradable soft helical microswimmers via two‐photon polymerization of the non‐toxic photocrosslinkable hydrogel gelatin methacryloyl (GelMA) is reported. GelMA microswimmers are fabricated with user‐defined geometry and rendered magnetically responsive by decorating their surface with magnetic nanoparticles. In contrast to previous rigid helical microrobots, the soft helical microswimmers can corkscrew above the step‐out frequency with relatively high values of forward velocity, suggesting an unprecedented self‐adaptive behavior. Cytotoxicity assays show the toxicity of GelMA is at least three orders of magnitude lower than that of poly(ethyleneglycol) diacrylates, which are widely used for fabricating hydrogel‐based microswimmers. GelMA microswimmers are fully degradable by collagenases. Furthermore, they support cell attachment and growth, and are gradually digested by cell‐released enzymes during culture. These non‐cytotoxic biodegradable hydrogel microswimmers will greatly expand their applications in medicine by eliminating the concerns of retrieving microrobots after fulfilling tasks in body.
Biodegradable soft helical microswimmers are successfully developed based on two‐photon photopolymerization of a gelatin derivative, GelMA. By decorating their surface with magnetic nanoparticles, these microswimmers can be manipulated by magnetic field. Because of the proteolytic cleavage of peptide domains in gelatin, microswimmers made of GelMA can be fully degraded by cell‐secreted proteases.
Abstract
The zeolite Cu(I)Y is promising for adsorptive removal of thiophenic sulfur compounds from transportation fuels. However, its application is seriously hindered by the instability of Cu(I), ...which is easily oxidized to Cu(II) even under atmospheric environment due to the coexistence of moisture and oxygen. Here, we report the adjustment of zeolite microenvironment from hydrophilic to superhydrophobic status by coating polydimethylsiloxane (yielding Cu(I)Y@P), which isolates moisture entering the pores and subsequently stabilizes Cu(I) despite the presence of oxygen. Cu(I) in Cu(I)Y@P is stable upon exposure to humid atmosphere for 6 months, while almost all Cu(I) is oxidized to Cu(II) in Cu(I)Y for only 2 weeks. The optimized Cu(I)Y@P material after moisture exposure can remove 532 μmol g
−1
of thiophene and is much superior to Cu(I)Y (116 μmol g
−1
), regardless of similar uptakes for unexposed adsorbents. Remarkably, Cu(I)Y@P shows excellent adsorption capacity of desulfurization for water-containing model fuel.
Advanced hydrogel systems that allow precise control of cells and their 3D microenvironments are needed in tissue engineering, disease modeling, and drug screening. Multiphoton lithography (MPL) ...allows true 3D microfabrication of complex objects, but its biological application requires a cell‐compatible hydrogel resist that is sufficiently photosensitive, cell‐degradable, and permissive to support 3D cell growth. Here, an extremely photosensitive cell‐responsive hydrogel composed of peptide‐crosslinked polyvinyl alcohol (PVA) is designed to expand the biological applications of MPL. PVA hydrogels are formed rapidly by ultraviolet light within 1 min in the presence of cells, providing fully synthetic matrices that are instructive for cell‐matrix remodeling, multicellular morphogenesis, and protease‐mediated cell invasion. By focusing a multiphoton laser into a cell‐laden PVA hydrogel, cell‐instructive extracellular cues are site‐specifically attached to the PVA matrix. Cell invasion is thus precisely guided in 3D with micrometer‐scale spatial resolution. This robust hydrogel enables, for the first time, ultrafast MPL of cell‐responsive synthetic matrices at writing speeds up to 50 mm s−1. This approach should enable facile photochemical construction and manipulation of 3D cellular microenvironments with unprecedented flexibility and precision.
A rapidly crosslinkable poly(vinyl alcohol) hydrogel photoresist is developed to synthesize modular 3D cell‐instructive microenvironments and to spatiotemporally control cell functions in culture via a multiphoton laser at high resolution. When cultured in 3D, single epithelial cells can self‐organize into miniature multicellular structures. This material allows ultrafast multiphoton photolithography and high‐precision cell manipulation in 3D culture, offering unprecedented opportunities for in situ tissue engineering and cell biology.
As a valuable traditional Chinese herbal medicine, Radix Astragali has attracted much attention due to its extensive pharmacological activities. In this study, density functional theory (DFT) was ...used thermodynamically and kinetically in detail to predict the antioxidant activity and reaction mechanisms involved in the free radical scavenging reactions of three representative isoflavonoids (formononetin, calycosin, and calycosin-7-glucoside) extracted from Radix Astragali. Three main mechanisms, including hydrogen atom transfer (HAT), proton transfer after electron transfer (SET-PT), and sequential proton loss electron transfer (SPLET) were examined by calculating the thermodynamic parameters. It was found that HAT is the predominant mechanism in the gas phase, while SPLET is supported in the solvent environment. The isoflavonoids' order of antioxidant activity was estimated as: calycosin > calycosin-7-glucoside > formononetin. For the calycosin compound, the result revealed the feasibility of double HAT mechanisms, which involve the formation of stable benzodioxazole with significantly reduced energy in the second H
/e
reaction. In addition, the potential energy profiles and kinetic calculations show that the reaction of
OH into the 3'-OH site of calycosin has a lower energy barrier (7.2 kcal/mol) and higher rate constant (4.55 × 10
M
s
) compared with other reactions in the gas phase.
Since bacterial infections seriously threaten human's health, considerable attention is devoted to the design of nanoscale antibacterial materials. Among them, metal nanoparticles cannot meet the ...requirements of durable antibacterial effects and are harmful to biological environments. In this study, environmentally friendly nanogels with durable antibacterial and antiadhesion properties are prepared by copolymerization of styrene, polycaprolactone‐hydroxyethyl methacrylate, and polyhexamethylene guanidine hydrochloride methacrylate. The resultant nanogels possess regular spherical morphologies with the size of about 200 nm. The nanogels exhibit a strong ability to kill bacteria and the mechanism is different from that of conventional antibacterial agent loaded nanoparticles. In addition, anti‐infection experiments explored by a wound model confirm the nanogels have the capability to prevent infection. Furthermore, the nanogels grafted on the surface of cotton fibers display good thermal stability, which is essential for finishing of fabrics. The cotton fabrics finished with nanogels can prevent the adhesion of bacteria by enhancing the hydrophobicity and the bacteriostatic rate. The antibacterial fabrics against Staphylococcus aureus and Escherichia coli are still more than 86% active after 50 times of mechanical washing. The biocompatible nanogels are unleachable from the antibacterial fabrics which demonstrate that they are ideal candidates for durable and environmental‐friendly nanoscaled antimicrobial materials.
In this study, environmentally friendly nanogels with durable antibacterial and antiadhesion properties are prepared by copolymerization of guanidine groups based monomers. The resultant inherent guanidine spherical nanogels can kill bacteria effectively and have the capability to prevent infection. Furthermore, the nanogels grafted on cotton fibers display good thermal stability. The cotton fabrics finished with nanogels can prevent the adhesion of bacteria permanently.
Bioprinting is a promising technique for facilitating the fabrication of engineered bone tissues for patient-specific defect repair and for developing in vitro tissue/organ models for ex vivo tests. ...However, polymer-based ink materials often result in insufficient mechanical strength, low scaffold fidelity and loss of osteogenesis induction because of the intrinsic swelling/shrinking and bioinert properties of most polymeric hydrogels. Here, we developed a human mesenchymal stem cells (hMSCs)-laden graphene oxide (GO)/alginate/gelatin composite bioink to form 3D bone-mimicking scaffolds using a 3D bioprinting technique. Our results showed that the GO composite bioinks (0.5GO, 1GO, 2GO) with higher GO concentrations (0.5, 1 and 2 mg/ml) improved the bioprintability, scaffold fidelity, compressive modulus and cell viability at day 1. The higher GO concentration increased the cell body size and DNA content, but the 2GO group swelled and had the lowest compressive modulus at day 42. The 1GO group had the highest osteogenic differentiation of hMSC with the upregulation of osteogenic-related gene (ALPL, BGLAP, PHEX) expression. To mimic critical-sized calvarial bone defects in mice and prove scaffold fidelity, 3D cell-laden GO defect scaffolds with complex geometries were successfully bioprinted. 1GO maintained the best scaffold fidelity and had the highest mineral volume after culturing in the bioreactor for 42 days. In conclusion, GO composite bioinks had better bioprintability, scaffold fidelity, cell proliferation, osteogenic differentiation and ECM mineralization than the pure alginate/gelatin system. The optimal GO group was 1GO, which demonstrated the potential for 3D bioprinting of bone tissue models and tissue engineering applications.
Display omitted
Nanoporous adsorbents are highly efficient in selectively capturing aromatic sulfur compounds such as thiophene, benzothiophene, dibenzothiophene, and 4,6-dimethyldibenzothiophene that are refractory ...to remove by traditional techniques from liquid hydrocarbon fuels. In the past decades, great progress has been made in design and fabrication of nanoporous adsorbents as well as the judicious strategies of promoting their performance for deep desulfurization. However to the best of our knowledge, a comprehensive review from this perspective has never been reported until now. Therefore, a review summarizing these nanoporous adsorbents and advanced strategies is highly anticipated. In this review, we provide an overview of the synthesis methods, improvement strategies, and prospective of the nanoporous adsorbents for applications with adsorptive desulfurization. The concerned materials cover most of the traditional and recently emerged nanoporous materials, and are introduced and basically grouped by material type. Each category is illustrated with some typical examples, and the fundamental principles on how to design and fabricate nanoporous adsorbents are highlighted. The adsorption mechanism is discussed in detail as well.
Traditional and recently emerged nanoporous adsorbents for deep desulfurization of liquid hydrocarbon fuels are summarized.
Hierarchically porous metal–organic frameworks (HP‐MOFs) have attracted great attention owing to their advantages over microporous MOFs in some applications. Despite many attempts, the development of ...a facile approach to generate HP‐MOFs remains a challenge. Herein we develop a new strategy, namely the modulation of cation valence, to create hierarchical porosity in MOFs. Some of the CuII metal nodes in MOFs can be transformed into CuI via reducing vapor treatment (RVT), which partially changes the coordination mode and thus breaks coordination bonds, resulting in the formation of HP‐MOF based on the original microporous MOF. Both the experimental results and the first‐principles calculation show that it is easy to tailor the amount of CuI and subsequent hierarchical porosity by tuning the RVT duration. It is found that the resultant HP‐MOFs perform much better in the capture of aromatic sulfides than the original microporous MOF.
Making the cut: Some of CuII nodes in the metal–organic framework (MOF) HKUST‐1 can be transformed into CuI by a reducing vapor treatment (RVT). This treatment partially changes the coordination mode of the Cu nodes and thus breaks coordination bonds, resulting in the formation of hierarchical pores from the original microporous HKUST‐1.
Hypoxia is a parameter related to many diseases. Ratiometric hypoxia probes often rely on a combination of an O2‐insensitive fluorophore and an O2‐sensitive phosphor in a polymer matrix, which ...require high cost and multi‐step synthesis of transition metal complexes. The two‐chromophore hypoxia probes encounter unfavorable energy transfer processes and different stabilities of the chromophores. Reported herein is a pure organic ratiometric hypoxia nanoprobe, assembled by a monochromophore, naphthalimide ureidopyrimidinone (BrNpA‐UPy), bridged by a bis‐UPy‐functionalized benzyl skeleton. The joint factors of quadruple hydrogen bonding, the rigid backbone of UPy, and bromine substitution of the naphthalimide derivative facilitate bright phosphorescence (ΦP=7.7 %, τP=3.2 ms) and fluorescence of the resultant nanoparticles (SNPs) at room temperature, which enable accurate, ratiometric, sensitive oxygen detection (Ksv=189.6 kPa−1) in aqueous solution as well as in living HeLa cells.
An organic hypoxia nanoprobe assembled by quadruple hydrogen bonds, shows efficient long‐lived phosphorescence (ΦP=7.7 %, τP=3.2 ms) and fluorescence from a monochromophore at room temperature and can be used for oxygen detection in water and living cells. This is the first example of ratiometric hypoxia sensing by supramolecular assemblies of an organic monochromophore.
PDF
