Considering the moderate acidity of aerosols, the formation of secondary organic aerosols (SOA) through acid-catalyzed heterogeneous reactions has become a recent concern. However, the detailed ...information on the multiphase chemistry of organic compounds adsorbed onto acidic aerosols remains uncertain. In this work, we investigated the multiphase chemical processes between methacrolein (MACR) and sulfuric acid (SA) and their relationship with SOA formation. Results show that the aqueous nanoparticle interface, especially when it is an acidic nanoparticle interface, is a perfect area to adsorb and accommodate MACR. The occurrence percentage of MACR on the interface is more than 70%. With the increase of SA concentration, the first solvation shell changed from only water to the mixture of SA and water, which facilitates the heterogeneous hydration reaction of MACR. Compared with the neutral nanoparticle interface, the acidic nanoparticle interface exhibits a better ability to uptake and accommodate gaseous carbonyl species. Moreover, SA can catalyze the hydration reaction of MACR inside the aqueous media, and the resulting oligomers contribute to the formation and growth of SOA. The hydration reaction indirectly promotes the continuous adsorption of MACR at the acidic nanoparticle interface. The rate constant shows a positive altitude dependence, and acid-catalyzed reactions have an important impact on environmental chemistry, such as cloud SOA formation, within the range of about 2–6 km. This study reports a complete description of the heterogeneous interactions between unsaturated carbonyl species and acidic nanoparticles by using molecular dynamics and quantum chemistry methods, aiming to provide some insights for the further study on heterogeneous chemistry and its role in the formation of tropospheric SOA.
Display omitted
•The multiphase chemistry of methacrolein is studied by a theoretical perspective.•The occurrence percentage of methacrolein on the nanoparticle interface is >70%.•Air-acid interface has a better uptake ability compared to the air-water interface.•Sulfuric acid can catalyze the hydration reaction in the bulk nanoparticle.•Acid-catalyzed methacrolein reaction is related to the formation of SOA.
Display omitted
The TiO2 nanosheets with exposed (010) facets were synthesized via facile surfactant self-assembly. Then, the TiO2 sheets were employed as scaffolding and deposited Ag/AgBr particles ...via improved oil/water self-assembly method. The TEM results suggested that Ag/AgBr particles well dispersed on the surface of TiO2 sheets with diameter 1–4 nm. The modified of Ag/AgBr enhanced the absorption in the visible light region, which was due to surface plasmonic resonance (SPR) of the metallic Ag clusters formed on the surface of AgBr particle. The as-prepared hierarchical composites photocatalyst Ag/AgBr/TiO2 exhibited excellent photocatalytic activity under nature solar-light irradiation and degraded ∼91.7% of Rhodamine (RhB) within 60 min. The degradation of colorless Bisphenol (BPA) further confirmed the photocatalytic abilities of Ag/AgBr/TiO2. The quenching tests exhibited that the Ag/AgBr/TiO2 composites photocatalytic degradation organic pollutions were mainly dominated by O2− oxidation reactions, while the h+ and OH have a minor contribution. The improved photocatalytic activities can be attributed to the suitable size of Ag/AgBr particles, abundant surface active sites, effective photogenerated electron-hole pair's separation, which significantly improve the photocatalytic activity.
With unique and tunable photoluminescence (PL) properties, carbon nanodots (CNDs) as a new class of optical tags have been extensively studied. Because of their merits of controllability and ...sensitivity to the surface of nanomaterials, electrochemical methods have already been adopted to study the intrinsic electronic structures of CNDs. In this review, we mainly deal with the electrochemical researches of CNDs, including preparation, PL mechanism, and biosensing.
The immune checkpoint proteins, programmed death receptor 1 (PD-1) and programmed death ligand 1 (PD-L1), are crucial for maintaining fetomaternal immune tolerance and immune escape in cancers. In ...this study, we performed a comprehensive immunohistochemical study of PD-L1 expression in a large cohort of trophoblastic tissues and tumors. We found that normal villi and hydatidiform moles showed a heterogeneous PD-L1 staining among trophoblast (strong in syncytiotrophoblast, moderate in intermediate trophoblast, and weak/negative in cytotrophoblast). Eleven exaggerated placental sites (100%) showed variable PD-L1 staining, whereas 7 (36.8%) of 19 placental site nodules/plaques were weakly positive for PD-L1 (P < .001). All gestational choriocarcinomas (CCs; n = 63), epithelioid trophoblastic tumors (n = 12), and placental site trophoblastic tumors (n = 41) were PD-L1 positive, with most showing strong staining. However, PD-L1 expression was lower in epithelioid trophoblastic tumors compared with placental site trophoblastic tumors and CCs (P = .004). Three presumably germ cell–derived pure CCs, the CC elements in 13 mixed germ cell tumors, and 4 gastric/rectal CCs were also positive for PD-L1, with widespread staining. The background nontrophoblastic tissues, such as endometrial glands, squamous cells, and adenocarcinomas, were PD-L1 negative. Western blot analysis showed that PD-L1 was expressed in all 3 trophoblastic cell lines. We conclude that PD-L1 is a sensitive but nonspecific marker for trophoblast and related tumors. The frequent strong PD-L1 expression suggests that immune checkpoint blockade could be a promising approach in treating trophoblastic tumors that merits further investigation.
•PD-L1 is widely expressed in trophoblastic tissues and related tumors.•Somatic CC shows strong PD-L1 expression.•PD-L1 is a sensitive but nonspecific mark for trophoblastic differentiation.•Our study generates a strong rationale for immunotherapy in trophoblastic tumors.
Display omitted
•Synthesis of Ag/AgBr/Bi2WO6 heterojunctions photocatalyst via oil/water self-assembly method.•Ag/AgBr/Bi2WO6 heterojunction can reduce the recombination of electrons and holes.•The ...composites exhibited excellent photocatalytic activity under visible-light irradiation.•Holes and O2− are the predominant active species for Ag/AgBr/Bi2WO6 under visible-light irradiation.
Visible-light sensitive photocatalyst Ag/AgBr/Bi2WO6 was successfully synthesized by oil/water self-assembly method. The crystalline structure, morphologies and optical properties of the as-prepared samples were investigated. The results revealed that the Ag/AgBr successfully introduced into the surface of Bi2WO6. The modified of Ag/AgBr enhanced the absorption in the visible-light region, due to surface plasmonic resonance of the metallic Ag. The activities of as-prepared samples were investigated by the degradation of RhB and phenol under the visible-light. Experimental results revealed that the Ag/AgBr/Bi2WO6 composites exhibit high visible-light photocatalytic activity compared with that of pure Ag/AgBr and Bi2WO6.
Human embryonic stem cells （hESCs） can self-renew indefinitely and differentiate into all cell types in the human body. Therefore, they are valuable in regenerative medicine, human developmental ...biology and drug discovery. A number of hESC lines have been derived from the Chinese population, but limited of them are available for research purposes. Here we report the derivation and characterization of two hESC lines derived from human blastocysts of Chinese origin. These hESCs express alkaline phosphatase and hESC-specific markers, including Oct4, Nanog, SSEA-3, SSEA-4, TRA- 1-60 and TRA-1-81. They also have high levels of telomerase activity and normal karyotypes. These ceils can form embryoid body in vitro and can be differentiated into all three germ layers in vivo by teratoma formation. The newly established hESCs will be distributed for research purposes. The availability of hESC lines from the Chinese population will facilitate studies on the differences in hESCs from different ethnic groups.
To explore the specific mechanism of circular RNA (circRNA) in the occurrence and development of hepatocellular carcinoma (HCC), and provide new ideas for its diagnosis and treatment.
Reverse ...transcription-quantitative polymerase chain reaction (RT-qPCR) was for evaluating the expression of circ_NOTCH3 in liver cancer tissues and matched normal tissues and related cell lines. After overexpression or co-expression of circ_NOTCH3 or microRNA (miRNA) in cells, the changes in cell function were analyzed. Bioinformatics analysis and dual luciferase report analysis were utilized to predict and verify the binding site between circ_NOTCH3 and miRNA. Western blotting was applied to detect gene expression alterations. Additionally,
tumor growth was also utilized to further assess the influence of knocking-down circ_NOTCH3 on the progression of HCC.
It was confirmed circ_NOTCH3 was highly expressed in HCC specimens and cells. The proliferation, migration, invasion, and oxaliplatin-resistance potential of HCC could be restrained by silencing circ_NOTCH3 or by ectopic expression of miR-875-5p
. In terms of mechanism, circ_NOTCH3 directly binds to miR-875-5p, regulating its activity by targeting the 3'-UTR of ZNF146. Overexpression of circ_NOTCH3 evidently overturned the diminishing influence of miR-875-5p mimics on HCC cells.
As an oncogene, circ_NOTCH3 can trigger the proliferation, invasion, migration, and oxaliplatin resistance of HCC cells through the miR-875-5p/ZNF146 axis, and may be a promising target for the treatment of HCC.
Cats have protractible claws to fold their tips to keep them sharp. They protract claws while hunting and pawing on slippery surfaces. Protracted claws by tendons and muscles of toes can help cats ...anchoring themselves steady while their locomotion trends to slip and releasing the hold while they retract claws intentionally. This research proposes a kind of modularized self-adaptive toe mechanism inspired by cat claws to improve the extremities' contact performance for legged robot. The mechanism is constructed with four-bar linkage actuated by contact reaction force and retracted by applied spring tension. A feasible mechanical design based on several essential parameters is introduced and an integrated Sole-Toe prototype is built for experimental evaluation. Mechanical self-adaption and actual contact performance on specific surface have been evaluated respectively on a biped walking platform and a bench-top mechanical testing.
Neuromorphic computing has been a candidate to work like human brains to deal with big data energy-efficiently beyond the von Neumann architecture. As an important part, artificial synapses based on ...waveguides with phase-change materials (PCMs) play a critical role in neural networks. However, because of demanding conditions of triggering intermediate phase states to achieve multilevel weights it is relatively difficult to obtain accurate multilevel weights. In this work, we designed a photonic synapse based on slot-ridge waveguides with multi-block Ge2Sb2Te5 (GST) to precisely and easily get multilevel weights by triggering the specific number of GST islands between crystalline and amorphous states. The properties of the GST material were analyzed by Raman spectroscopy and spectroscopic ellipsometry and the nonlinearity factor of photonic synaptic weights was optimized for the number of GST islands. The recognition tasks of MNIST and the optical recognition of NIST were performed by multilayer perceptron, and the optimal accuracy of the optical recognition of NIST was 92.7 % for 5 GST islands. The accuracy of MNIST was improved by 2 % for 5 GST islands compared with that of 2 GST islands. Besides, the electro-thermal phase transition conditions of crystallization and reamorphization were also obtained by simulation. This work will open the way to precisely and easily achieve photonic synapses with multilevel weights in the future.
•This work achieves multilevel weights of photonic synapses with GST to avoid the demanding triggering condition.•Photonic synapses based on slot-ridge waveguides with GST achieve multilevel weights by dividing the block GST into islands.•The nonlinearity factor is optimized for the number of islands in the mapping between normalized transmission and weights.•The optimal accuracy of the optical recognition of NIST is 92.7% while that of MNIST is improved by 2%.•The electro-thermal phase transition conditions are obtained by using Joule heat model.
Graph sampling frequently compresses a large graph into a limited screen space. This paper proposes a hierarchical structure model that partitions scale-free graphs into three blocks: the core, which ...captures the underlying community structure, the vertical graph, which represents minority structures that are important in visual analysis, and the periphery, which describes the connection structure between low-degree nodes. A new algorithm named hierarchical structure sampling (HSS) was then designed to preserve the characteristics of the three blocks, including complete replication of the connection relationship between high-degree nodes in the core, joint node/degree distribution between high- and low-degree nodes in the vertical graph, and proportional replication of the connection relationship between low-degree nodes in the periphery. Finally, the importance of some global statistical properties in visualization was analyzed. Both the global statistical properties and local visual features were used to evaluate the proposed algorithm, which verify that the algorithm can be applied to sample scale-free graphs with hundreds to one million nodes from a visualization perspective.
PDF
