Backscattering suppression in silicon-on-insulator (SOI) is one of the central issues to reduce energy loss and signal distortion, enabling for capability improvement of modern information processing ...systems. Valley physics provides an intriguing way for robust information transfer and unidirectional coupling in topological nanophotonics. Here we realize topological transport in a SOI valley photonic crystal slab. Localized Berry curvature near zone corners guarantees the existence of valley-dependent edge states below light cone, maintaining in-plane robustness and light confinement simultaneously. Topologically robust transport at telecommunication is observed along two sharp-bend interfaces in subwavelength scale, showing flat-top high transmission of ~10% bandwidth. Topological photonic routing is achieved in a bearded-stack interface, due to unidirectional excitation of valley-chirality-locked edge state from the phase vortex of a nanoscale microdisk. These findings show the prototype of robustly integrated devices, and open a new door towards the observation of non-trivial states even in non-Hermitian systems.
The photocatalyzed ortho‐selective migration on a pyridyl ring has been achieved for the site‐selective trifluoromethylative pyridylation of unactivated alkenes. The overall process is initiated by ...the selective addition of a CF3 radical to the alkene to provide a nucleophilic alkyl radical intermediate, which enables an intramolecular endo addition exclusively to the ortho‐position of the pyridinium salt. Both secondary and tertiary alkyl radicals are well‐suited for addition to the C2‐position of pyridinium salts to ultimately provide synthetically valuable C2‐fluoroalkyl functionalized pyridines. Moreover, the method was successfully applied to the reaction with P‐centered radicals. The utility of this transformation was further demonstrated by the late‐stage functionalization of complex bioactive molecules.
Remote migration: The photocatalyzed ortho‐selective migration on a pyridyl ring has been achieved for the site‐selective trifluoromethylative pyridylation of unactivated alkenes under mild reaction conditions. Notably, this method could be successfully extended to tertiary radicals to forge quaternary C centers bearing C2‐substituted pyridyl groups, overriding the commonly observed preference for the C4 addition.
Conspectus Metal–organic frameworks (MOFs) have been attracting tremendous attention owing to their great structural diversity and functional tunability. Despite numerous inherent merits and big ...progress in the fundamental research (synthesizing new compounds, discovering new structures, testing associated properties, etc.), poor chemical stability of most MOFs severely hinders their involvement in practical applications, which is the final goal for developing new materials. Therefore, constructing new stable MOFs or stabilizing extant labile MOFs is quite important. As with them, some “potential” applications would come true and a lot of new applications under harsh conditions can be explored. Efficient strategies are being pursued to solve the stability problem of MOFs and thereby achieve and expand their applications. In this Account, we summarize the research advance in the design and synthesis of chemically stable MOFs, particularly those stable in acidic, basic, and aqueous systems, as well as in the exploration of their applications in several expanding fields of environment, energy, and food safety, which have been dedicated in our lab over the past decade. The strategies for accessing stable MOFs can be classified into: (a) assembling high-valent metals (hard acid, such as Zr4+, Al3+) with carboxylate ligands (hard base) for acid-stable MOFs; (b) combining low-valent metals (soft acid, such as Co2+, Ni2+) and azolate ligands (soft base, such as pyrazolate) for alkali-resistant MOFs; (c) enhancing the connectivity of the building unit; (d) contracting or rigidifying the ligand; (e) increasing the hydrophobicity of the framework; and (f) substituting liable building units with stable ones (such as metal metathesis) to obtain robust MOFs. In addition, other factors, including the geometry and symmetry of building units, framework–framework interaction, and so forth, have also been taken into account in the design and synthesis of stable MOFs. On the basis of these approaches, the stability of resulting MOFs under corresponding conditions has been remarkably enhanced. With high chemical stability achieved, the MOFs have found many new and significant applications, aiming at addressing global challenges related to environmental pollution, energy shortage, and food safety. A series of stable MOFs have been constructed for detecting and eliminating contaminations. Various fluorescent MOFs were rationally customized to be powerful platforms for sensing hazardous targets in food and water, such as dioxins, antibiotics, veterinary drugs, and heavy metal ions. Some hydrophobic MOFs even showed effective and specific capture of low-concentration volatile organic compounds. Novel MOFs with record-breaking acid/base/nucleophilic regent resistance have expanded their application scope under harsh conditions. BUT-8(Cr)A, as the most acid-stable MOF yet, showed reserved structural integrity in concentrated H2SO4 and recorded high proton conductivity; the most alkali-resistant MOF, PCN-601, retained crystallinity even in boiling saturated NaOH aqueous solution, and such base-stable MOFs composed of non-noble metal clusters and poly pyrazolate ligands also demonstrated great potential in heterogeneous catalysis in alkaline/nucleophilic systems for the first time. It is believed that this Account will provide valuable references on stable MOFs’ construction as well as application expansion toward harsh conditions, thereby being helpful to promote MOF materials to step from fundamental research to practical applications.
Recent research in topological photonics has not only proposed and realized novel topological phenomena such as one‐way broadband propagation and robust transport of light, but also designed and ...fabricated photonic devices with high‐performance indexes, which are immune to fabrication errors such as defects or disorders. Photonic crystals, which are periodic optical structures with the advantages of good light field confinement and multiple adjusting degrees of freedom, provide a powerful platform to control the flow of light. With the topology defined in the reciprocal space, photonic crystals have been widely used to reveal different topological phases of light and demonstrate topological photonic functionalities. This review presents the physics of topological photonic crystals with different dimensions, models, and topological phases. The design methods of topological photonic crystals are introduced. Furthermore, the applications of topological photonic crystals in passive and active photonics are reviewed. These studies pave the way for applying topological photonic crystals in practical photonic devices.
For the ability to improve the robustness of photonic devices under different kinds of defects, topological photonic crystals have attracted increasing attention and have been used as a platform for studying intriguing physical phenomena and realizing novel functional devices. This review provides an introduction to the fundamental physics, optical design, and promising applications of topological photonic crystals in different dimensions.
Periodontitis is a widespread disease characterized by inflammation‐induced progressive damage to the tooth‐supporting structures until tooth loss occurs. The regeneration of lost/damaged support ...tissue in the periodontium, including the alveolar bone, periodontal ligament, and cementum, is an ambitious purpose of periodontal regenerative therapy and might effectively reduce periodontitis‐caused tooth loss. The use of stem cells for periodontal regeneration is a hot field in translational research and an emerging potential treatment for periodontitis. This concise review summarizes the regenerative approaches using either culture‐expanded or host‐mobilized stem cells that are currently being investigated in the laboratory and with preclinical models for periodontal tissue regeneration and highlights the most recent evidence supporting their translational potential toward a widespread use in the clinic for combating highly prevalent periodontal disease. We conclude that in addition to in vitro cell‐biomaterial design and transplantation, the engineering of biomaterial devices to encourage the innate regenerative capabilities of the periodontium warrants further investigation. In comparison to cell‐based therapies, the use of biomaterials is comparatively simple and sufficiently reliable to support high levels of endogenous tissue regeneration. Thus, endogenous regenerative technology is a more economical and effective as well as safer method for the treatment of clinical patients. Stem Cells Translational Medicine 2019;8:392–403
Periodontal regeneration can potentially be achieved via either the in vitro design of cell‐material constructs that may undergo remodeling and revascularization to integrate with the host tissue following transplantation or based on the in vivo manipulation of the cell‐material interplay at the target site to recruit endogenous stem cells to regenerate new tissues.
Tumor metastasis is a hallmark of cancer. The communication between cancer-derived exosomes and stroma plays an irreplaceable role in facilitating pre-metastatic niche formation and cancer ...metastasis. However, the mechanisms underlying exosome-mediated pre-metastatic niche formation during colorectal cancer (CRC) liver metastasis remain incompletely understood. Here we identified HSPC111 was the leading upregulated gene in hepatic stellate cells (HSCs) incubated with CRC cell-derived exosomes. In xenograft mouse model, CRC cell-derived exosomal HSPC111 facilitated pre-metastatic niche formation and CRC liver metastases (CRLM). Consistently, CRC patients with liver metastasis had higher level of HSPC111 in serum exosomes, primary tumors and cancer-associated fibroblasts (CAFs) in liver metastasis than those without. Mechanistically, HSPC111 altered lipid metabolism of CAFs by phosphorylating ATP-citrate lyase (ACLY), which upregulated the level of acetyl-CoA. The accumulation of acetyl-CoA further promoted CXCL5 expression and secretion by increasing H3K27 acetylation in CAFs. Moreover, CXCL5-CXCR2 axis reinforced exosomal HSPC111 excretion from CRC cells and promoted liver metastasis. These results uncovered that CRC cell-derived exosomal HSPC111 promotes pre-metastatic niche formation and CRLM via reprogramming lipid metabolism in CAFs, and implicate HSPC111 may be a potential therapeutic target for preventing CRLM.
Microglial activation and neuroinflammation induced by amyloid β (Aβ) play pivotal roles in Alzheimer’s disease (AD) pathogenesis. Astragaloside IV (AS-IV) is one of the major active compounds of the ...traditional Chinese medicine Astmgali Radix. It has been reported that AS-IV could protect against Aβ-induced neuroinflammation and cognitive impairment, but the underlying mechanisms need to be further clarified. In this study, the therapeutic effects of AS-IV were investigated in an oligomeric Aβ (oAβ) induced AD mice model. The effects of AS-IV on microglial activation, neuronal damage and reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase expression were further studied. Different doses of AS-IV were administered intragastrically once a day after intracerebroventricularly oAβ injection. Results of behavioral experiments including novel object recognition (NOR) test and Morris water maze (MWM) test revealed that AS-IV administration could significantly ameliorate oAβ-induced cognitive impairment in a dose dependent manner. Enzyme linked immunosorbent assay (ELISA) results showed that increased levels of reactive oxygen species (ROS), tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β) and IL-6 in hippocampal tissues induced by oAβ injection were remarkably inhibited after AS-IV treatment. OAβ induced microglial activation and neuronal damage was significantly suppressed in AS-IV-treated mice brain, observed in immunohistochemistry results. Furthermore, oAβ upregulated protein expression of NADPH oxidase subunits gp91phox, p47phox, p22phox and p67phox were remarkably reduced by AS-IV in Western blotting assay. These results revealed that AS-IV could ameliorate oAβ-induced cognitive impairment, neuroinflammation and neuronal damage, which were possibly mediated by inhibition of microglial activation and down-regulation of NADPH oxidase protein expression. Our findings provide new insights of AS-IV for the treatment of neuroinflammation related diseases such as AD.
Environmental inspection is to use GIS technology to design an environmental inspection network. The information collected through environmental testing can be saved and displayed in time through ...GIS, and the selected evaluation field can be monitored and analyzed in detail. This is the basis of scientific environmental management and environmental law enforcement supervision, and the basic work of environmental protection. The central goal of environmental monitoring is to provide data on the status quo and trend of environmental quality, judge environmental quality, assess current major environmental issues, and contribute to environmental management. Based on the analysis and classification of related literature, this paper adopts the method of literature induction to analyze the development trend of current research on the improvement and upgrade of network theory by domestic and foreign scholars. On this basis, the research on the network theory of improvement and upgrade is divided into three parts: the research on the dynamic factors of the upgrade, the research on the upgrade mechanism, and the research on the upgrade path. In China, the sources of PM2.5 are very complex, most of which come from the linear contribution of primary particulate matter. Therefore, the improvement of the response surface model and the establishment of real-time environmental detection and analysis tools suitable for PM2.5 emission characteristics and environmental concentration have high application value. The source of PM2.5 in indoor air environment can be divided into two parts. One is the emission of PM2.5 pollution sources in indoor buildings, and the other is the spread of PM2.5 pollutants from outdoor air to the indoor environment. In order to deal with air pollutants, we adopt pollutant emission control technology and control pollutant emission policies to achieve air pollution control.
Arrestins recognize different receptor phosphorylation patterns and convert this information to selective arrestin functions to expand the functional diversity of the G protein-coupled receptor ...(GPCR) superfamilies. However, the principles governing arrestin-phospho-receptor interactions, as well as the contribution of each single phospho-interaction to selective arrestin structural and functional states, are undefined. Here, we determined the crystal structures of arrestin2 in complex with four different phosphopeptides derived from the vasopressin receptor-2 (V2R) C-tail. A comparison of these four crystal structures with previously solved Arrestin2 structures demonstrated that a single phospho-interaction change results in measurable conformational changes at remote sites in the complex. This conformational bias introduced by specific phosphorylation patterns was further inspected by FRET and
H NMR spectrum analysis facilitated via genetic code expansion. Moreover, an interdependent phospho-binding mechanism of phospho-receptor-arrestin interactions between different phospho-interaction sites was unexpectedly revealed. Taken together, our results provide evidence showing that phospho-interaction changes at different arrestin sites can elicit changes in affinity and structural states at remote sites, which correlate with selective arrestin functions.
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