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1.
Phys Rev Lett ; 124(2): 027203, 2020 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-32004033

RESUMO

Spin waves can probe the Dzyaloshinskii-Moriya interaction (DMI), which gives rise to topological spin textures, such as skyrmions. However, the DMI has not yet been reported in yttrium iron garnet (YIG) with arguably the lowest damping for spin waves. In this work, we experimentally evidence the interfacial DMI in a 7-nm-thick YIG film by measuring the nonreciprocal spin-wave propagation in terms of frequency, amplitude, and most importantly group velocities using all electrical spin-wave spectroscopy. The velocities of propagating spin waves show chirality among three vectors, i.e., the film normal direction, applied field, and spin-wave wave vector. By measuring the asymmetric group velocities, we extract a DMI constant of 16 µJ/m^{2}, which we independently confirm by Brillouin light scattering. Thickness-dependent measurements reveal that the DMI originates from the oxide interface between the YIG and garnet substrate. The interfacial DMI discovered in the ultrathin YIG films is of key importance for functional chiral magnonics as ultralow spin-wave damping can be achieved.

2.
Sci Adv ; 5(11): eaav4355, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31700996

RESUMO

Recently, several captivating topological structures of electric dipole moments (e.g., vortex, flux closure) have been reported in ferroelectrics with reduced size/dimensions. However, accurate polarization distribution of these topological ferroelectric structures has never been experimentally obtained. We precisely measure the polarization distribution of an individual ferroelectric vortex in PbTiO3/SrTiO3 superlattices at the subunit cell level by using the atomically resolved integrated differential phase contrast imaging in an aberration-corrected scanning transmission electron microscope. We find, in vortices, that out-of-plane polarization is larger than in-plane polarization, and that downward polarization is larger than upward polarization. The polarization magnitude is closely related to tetragonality. Moreover, the contribution of the Pb─O bond to total polarization is highly inhomogeneous in vortices. Our precise measurement at the subunit cell scale provides a sound foundation for mechanistic understanding of the structure and properties of a ferroelectric vortex and lattice-charge coupling phenomena in these topological ferroelectric structures.

3.
Fish Shellfish Immunol ; 95: 546-555, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31704205

RESUMO

Interleukin 6 (IL-6) is a pleiotropic cytokine that plays important role in mediating the innate and adaptive immune responses against pathogen infection. In this study, an IL-6 homolog (Ls-IL6) was identified and characterized from humphead snapper, Lutjanus sanguineus. The full-length cDNA of Ls-IL6 was 1066 bp, containing an open reading frame (ORF) of 639 bp encoding 212 amino acids, 5' untranslated region(UTR) of 63 bp and 3' UTR of 605 bp. The predicted Ls-IL6 protein had typical motif of IL-6 family and shared high identities to teleost IL-6s. Ls-IL6 extensively expressed in various tissues, and the highest expression of Ls-IL6 was detected in head kidney, spleen and thymus. In vivo, the transcript levels of Ls-IL6 were significantly up-regulated in response to Vibrio harveyi infection. Moreover, the DNA plasmid containing the OmpW of V. harveyi together with the gene encoding Ls-IL6 were successfully constructed and administered to fish, the protective efficacy of Ls-IL6 was investigated. Compared with the pcDNA-OmpW group, the level of specific antibodies against V. harveyi increased in pcDNA-IL6-OmpW injected group. After V. harveyi infection, the pcDNA-IL6-OmpW vaccinated fish showed higher relative percent survival (76%) than the relative survival of fish immunized with pcDNA-OmpW (60%). These results indicated that Ls-IL6 was involved in immune response against V. harveyi infection and could be applied as a promising adjuvant for DNA vaccines against V. harveyi.

4.
Int J Mol Med ; 44(5): 1833-1843, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31545400

RESUMO

The dysregulation of microRNA­939­5p (miR­939) is involved in the development of multiple types of human cancer. However, the expression and roles of miR­939 in osteosarcoma (OS) have yet to be clarified. The expression level of miR­939 in OS was measured using reverse transcription quantitative polymerase chain reaction (RT­qPCR). A Cell Counting Kit­8 assay, flow cytometry analysis, Transwell migration and invasion assays, and a tumor xenograft assay were employed to explore the effects of miR­939 in OS cells. Bioinformatics analysis, RT­qPCR, western blot analysis and luciferase reporter assays were performed to explore its underlying mechanism. Expression of miR­939 was decreased in both OS tissues and cell lines. The decreased miR­939 expression was notably correlated with clinical stage and distant metastasis in patients with OS, where low miR­939 levels were correlated with lower overall survival. miR­939 overexpression decreased OS cell proliferation, migration and invasion in vitro; induced cell apoptosis, and impaired tumor growth in vivo. Mechanistically, insulin­like growth factor 1 receptor (IGF­1R) was characterized as direct target gene of miR­939 in OS. The tumor­suppressing effects of miR­939 in OS cells were imitated by IGF­1R knockdown. In addition, exogenous IGF­1R expression abolished the tumor suppressive roles of miR­939 in OS cells. miR­939 was implicated in the deactivation of the PI3K/Akt pathway in OS in vitro and in vivo through regulating IGF­1R expression. The present study demonstrated that miR­939 exerted tumor­suppressing roles in the malignancy of OS cells by directly targeting IGF­1R and inactivating the PI3K/AKT pathway. Therefore, this miRNA may be a promising target for anticancer therapy in patients with OS.

5.
Fish Shellfish Immunol ; 93: 781-788, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31326588

RESUMO

Nile tilapia (Oreochromis niloticus) is a pivotal economic fish that has been plagued by Streptococcus infections. Tumor necrosis factor receptor-associated factor 5 (TRAF5) is a crucial adaptor molecule, which can trigger downstream signaling cascades involved in immune pathway. In this study, Nile tilapia TRAF5 coding sequence (named OnTRAF5) was obtained, which contained typical functional domains, such as RING, zinc finger, coiled-coil and MATH domain. Different from other TRAF molecules, OnTRAF5 had shown relatively low identify with its homolog, and it was clustered into other teleost TRAF5 proteins. qRT-PCR was used to analysis the expression level of OnTRAF5 in gill, skin, muscle, head kidney, heart, intestine, thymus, liver, spleen and brain, In healthy Nile tilapia, the expression level of OnTRAF5 in intestine, gill and spleen were significantly higher than other tissues. While under Streptococcus agalactiae infection, the expression level of OnTRAF5 was improved significantly in all detected organs. Additionally, over-expression WT OnTRAF5 activated NF-κB, deletion of RING or zinc finger caused the activity impaired. In conclusion, OnTRAF5 participate in anti-bacteria immune response and is crucial for the signaling transduction.


Assuntos
Imunidade Adaptativa/genética , Ciclídeos/genética , Doenças dos Peixes/imunologia , Regulação da Expressão Gênica/imunologia , Imunidade Inata/genética , Fator 5 Associado a Receptor de TNF/genética , Sequência de Aminoácidos , Animais , Ciclídeos/imunologia , Proteínas de Peixes/química , Proteínas de Peixes/genética , Proteínas de Peixes/imunologia , Perfilação da Expressão Gênica/veterinária , Filogenia , Alinhamento de Sequência/veterinária , Infecções Estreptocócicas/imunologia , Infecções Estreptocócicas/veterinária , Streptococcus agalactiae/fisiologia , Fator 5 Associado a Receptor de TNF/química , Fator 5 Associado a Receptor de TNF/imunologia
6.
Nano Lett ; 19(8): 5070-5076, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31322902

RESUMO

Phonon polaritons hold potential prospects of nanophotonic applications at the mid- and far-infrared wavelengths. However, their experimental investigation in the far-infrared range has long been a technical challenge due to the lack of suitable light sources and detectors. To obviate these difficulties, here we use an electron probe with sub-10 meV energy resolution and subnanometer spatial resolution to study far-infrared surface phonon polaritons (∼50-70 meV) in ZnO nanostructures. We observe ultraslow propagation and interference fringes of propagating surface phonon polaritons and obtain their dispersion relation through measurements in the coordinate space. By mapping localized modes in nanowires and flakes, we reveal their localized nature and investigate geometry and size effects. Associated with simulation, we show that surface phonon polariton behaviors can be well described by the local continuum dielectric model. Our work paves the way for spatial-resolved investigation of surface phonon polaritons by electron probes and forwards polaritonics in the far-infrared range.

7.
Int Immunopharmacol ; 75: 105741, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31323531

RESUMO

Sepsis is a potentially fatal systemic inflammatory response syndrome caused by infection. In this study, we evaluated the effects of MCP-induced protein 1 (MCPIP1), a recently discovered inflammation-related ribonuclease, on sepsis-induced acute lung injury (ALI) and investigated the underlying mechanisms. Cecal ligation puncture and lipopolysaccharide induction were performed on Sprague-Dawley rats and RAW264.7 cells, respectively, to establish sepsis-induced ALI models. The proteasome inhibitor MG132 used as an activator of MCPIP1 overexpression, and we showed that MG132 can indeed increase the expression of MCPIP1. MCPIP1 overexpression induced by MG132 alleviated sepsis-induced pathologic changes, water content and protein leakage in the lungs, and induction of systemic inflammatory mediators, and improved the 7-day mortality rate in the model rats. We also showed that MCPIP1 p showed romoted macrophage polarization from the M1 to the M2 type in sepsis-induced ALI. Furthermore, MCPIP1-enhanced M2 polarization was inhibited by an MCPIP1-targeting small interfering RNA (siMCPIP1) in RAW264.7 cells. Further mechanistic studies showed that the promotive effect of MCPIP1 on M2 polarization was related to the inhibition of c-Jun N-terminal kinase (JNK) and its downstream transcription factor c-Myc in the in vitro model. Conversely, siMCPIP1 transfection resulted in the recovery of JNK and c-Myc expression in LPS-treated cells. Taken together, these findings indicate that MCPIP1 plays a protective role in sepsis-induced ALI by modulating macrophage polarization through inhibition of the JNK/c-Myc signaling pathway. Our study presents a potentially novel therapeutic strategy for the treatment of lung injury involving the inflammatory cascade.

8.
Nat Chem ; 11(8): 730-736, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31308494

RESUMO

Two-dimensional materials show a variety of promising properties, and controlling their growth is an important aspect for practical applications. To this end, active species such as hydrogen and oxygen are commonly introduced into reactors to promote the synthesis of two-dimensional materials with specific characteristics. Here, we demonstrate that fluorine can play a crucial role in tuning the growth kinetics of three representative two-dimensional materials (graphene, hexagonal boron nitride and WS2). When growing graphene by chemical vapour deposition on a copper foil, fluorine released from the decomposition of a metal fluoride placed near the copper foil greatly accelerates the growth of the graphene (up to a rate of ~200 µm s-1). Theoretical calculations show that it does so by promoting decomposition of the methane feedstock, which converts the endothermic growth process to an exothermic one. We further show that the presence of fluorine also accelerates the growth of two-dimensional hexagonal boron nitride and WS2.

9.
Int Immunopharmacol ; 73: 312-320, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31129418

RESUMO

Progressive lung injury and pulmonary inflammation can be induced by an intraperitoneal injection of lipopolysaccharide (LPS). Interleukin-1ß (IL-1ß) is a key pro-inflammatory cytokine that can further exaggerate inflammation, which is cleaved and activated by the NALP3 inflammasome. Although the nuclear receptor Rev-erbα attenuates the level of LPS-induced pulmonary inflammation, the mechanism remains unclear. In this study, we investigated the influence of LPS-induced production of IL-1ß and Rev-erbα on the development of lung inflammation. Herein, we demonstrate that Rev-erbα reduces IL-1ß production and lung injury following an intraperitoneal injection of LPS, which is dependent on the NF-κB/NALP3 pathway. Thus, Rev-erbα is able to decrease the extent of acute lung injury by regulating IL-1ß production. This mechanism may represent a potential novel therapeutic approach for lung injury.


Assuntos
Lesão Pulmonar Aguda/imunologia , NF-kappa B/imunologia , Proteína 3 que Contém Domínio de Pirina da Família NLR/imunologia , Membro 1 do Grupo D da Subfamília 1 de Receptores Nucleares/imunologia , Lesão Pulmonar Aguda/induzido quimicamente , Lesão Pulmonar Aguda/patologia , Animais , Glicina/análogos & derivados , Glicina/farmacologia , Interleucina-1beta/imunologia , Isoquinolinas/farmacologia , Lipopolissacarídeos , Pulmão/efeitos dos fármacos , Pulmão/metabolismo , Pulmão/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Membro 1 do Grupo D da Subfamília 1 de Receptores Nucleares/agonistas , Membro 1 do Grupo D da Subfamília 1 de Receptores Nucleares/antagonistas & inibidores , Células RAW 264.7 , Transdução de Sinais , Tiofenos/farmacologia
10.
Medicine (Baltimore) ; 98(19): e15582, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31083238

RESUMO

BACKGROUND: We designed the study to investigate whether methotrexate, doxorubicin, and cisplatinum (MAP) chemotherapy strategy was still the preferred option for the survival of osteosarcoma patients. METHOD: We collected some trials of osteosarcoma to make a meta-analysis first. Then, we retrospectively collected data from 115 patients with osteosarcoma and performed further analysis to verify the impact of MAP regimen on the survival of patients. RESULTS: Seven studies including 3433 participants met the preliminary inclusion criteria. Meta-analysis of the 3-year disease-free survival (odds ratio [OR] = 1.06, 95% confidence interval [CI]: 0.88-1.28; P = .52) and overall survival (OR = 1.21, 95% CI: 0.70-2.11; P = .54), 5-year disease-free survival (OR = 1.07, 95% CI: 0.87-1.30; P = .54) and overall survival (OR = 0.86, 95% CI: 0.65-1.12; P = .26), and mortality rate (OR = 0.90, 95% CI: 0.70-1.17; P = .44), showed no statistically significant differences. The most common grade 3/4 adverse events were neutropenia (498 [85.9%] patients in MAP vs 533 [93.3%] in MAP plus ifosfamide and etoposide, or other adjuvant therapy drugs [MAP]). MAP was associated with less frequent toxicities than MAP group with statistical significance in thrombocytopenia, febrile neutropenia, anemia, and hypophosphatemia. The same phenomenon could also be seen in the analysis of clinical data. CONCLUSION: MAP regimen remains the preferred option for osteosarcoma chemotherapy.


Assuntos
Antineoplásicos/uso terapêutico , Neoplasias Ósseas/tratamento farmacológico , Cisplatino/uso terapêutico , Doxorrubicina/uso terapêutico , Metotrexato/uso terapêutico , Osteossarcoma/tratamento farmacológico , Antineoplásicos/efeitos adversos , Neoplasias Ósseas/mortalidade , Cisplatino/efeitos adversos , Doxorrubicina/efeitos adversos , Quimioterapia Combinada , Feminino , Humanos , Masculino , Metotrexato/efeitos adversos , Osteossarcoma/mortalidade , Estudos Retrospectivos , Análise de Sobrevida
11.
Nature ; 570(7759): 91-95, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31118514

RESUMO

The development of two-dimensional (2D) materials has opened up possibilities for their application in electronics, optoelectronics and photovoltaics, because they can provide devices with smaller size, higher speed and additional functionalities compared with conventional silicon-based devices1. The ability to grow large, high-quality single crystals for 2D components-that is, conductors, semiconductors and insulators-is essential for the industrial application of 2D devices2-4. Atom-layered hexagonal boron nitride (hBN), with its excellent stability, flat surface and large bandgap, has been reported to be the best 2D insulator5-12. However, the size of 2D hBN single crystals is typically limited to less than one millimetre13-18, mainly because of difficulties in the growth of such crystals; these include excessive nucleation, which precludes growth from a single nucleus to large single crystals, and the threefold symmetry of the hBN lattice, which leads to antiparallel domains and twin boundaries on most substrates19. Here we report the epitaxial growth of a 100-square-centimetre single-crystal hBN monolayer on a low-symmetry Cu (110) vicinal surface, obtained by annealing an industrial copper foil. Structural characterizations and theoretical calculations indicate that epitaxial growth was achieved by the coupling of Cu <211> step edges with hBN zigzag edges, which breaks the equivalence of antiparallel hBN domains, enabling unidirectional domain alignment better than 99 per cent. The growth kinetics, unidirectional alignment and seamless stitching of the hBN domains are unambiguously demonstrated using centimetre- to atomic-scale characterization techniques. Our findings are expected to facilitate the wide application of 2D devices and lead to the epitaxial growth of broad non-centrosymmetric 2D materials, such as various transition-metal dichalcogenides20-23, to produce large single crystals.

12.
Nanoscale ; 11(15): 7474-7480, 2019 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-30942225

RESUMO

For alkali-metal ion batteries, revealing the phase transformation and the ion migration dynamics in the electrodes is vital for understanding how the electrodes work and thereby how we can improve them. Here, using in situ transmission electron microscopy, we track the structural evolution and migration dynamics during sodium insertion into TiS2 nanostructures with the lattice fringe resolution. We find that the sodiation process of TiS2 is initiated by an intercalation reaction and followed by a conversion reaction. From the same reaction event, the velocity of intercalation/conversion phase boundary migration is found to be ∼1.0-1.7 nm s-1, while the pristine/intercalation phase boundary migrates at a velocity of ∼2.5 nm s-1. The sodium migration leads to structural fracture to form nanometer-sized domains (∼3 nm) with volume expansion. During migration, Na prefers to transport along specific directions. Furthermore, a superstructured Na0.25TiS2 intermediate phase with ordered Na ions occupied within the (0001) plane is formed at the reaction front, which is different from the common staging phase. These findings help us understand the working principle and the failure mechanism of the sodium ion battery and also provide useful insights into the general ionic doping of transition metal dichalcogenides.

13.
Nat Nanotechnol ; 14(7): 691-697, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31011219

RESUMO

Spin waves may constitute key components of low-power spintronic devices. Antiferromagnetic-type spin waves are innately high-speed, stable and dual-polarized. So far, it has remained challenging to excite and manipulate antiferromagnetic-type propagating spin waves. Here, we investigate spin waves in periodic 100-nm-wide stripe domains with alternating upward and downward magnetization in La0.67Sr0.33MnO3 thin films. In addition to ordinary low-frequency modes, a high-frequency mode around 10 GHz is observed and propagates along the stripe domains with a spin-wave dispersion different from the low-frequency mode. Based on a theoretical model that considers two oppositely oriented coupled domains, this high-frequency mode is accounted for as an effective antiferromagnetic spin-wave mode. The spin waves exhibit group velocities of 2.6 km s-1 and propagate even at zero magnetic bias field. An electric current pulse with a density of only 105 A cm-2 can controllably modify the orientation of the stripe domains, which opens up perspectives for reconfigurable magnonic devices.

14.
Front Pharmacol ; 10: 197, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31024295

RESUMO

Background: A tibia shaft fracture is one of the most common long bone fractures, with two general types, open fracture and close fracture. However, there is no universally accepted guideline suggesting which treatment to use under certain circumstances. Therefore, a comprehensive network meta-analysis (NMA) is needed to summarize existing studies and to provide more credible data-based medical guidelines. Methods: Available literature was identified by searching medical databases with relevant key terms. Studies that met the inclusion and exclusion criteria, baseline, intervention, and the outcome of treatments, were extracted. A comparative connection of these studies was demonstrated through net plots. Continuous variables and binary variables were reported as mean difference (MD) and odds ratio (OR) with a 95% credible interval (CrI), respectively. The comparison of direct and indirect outcome and their P-value were listed in the node-splitting table. Treatments for each endpoint were ranked by their surface under the cumulative ranking curve (SUCRA) value. A heat plot was created to illustrate the contribution of raw data and the inconsistency between direct and indirect comparisons. Results: According to the search strategy, 697 publications were identified, and 25 records were included, involving 3,032 patients with tibia shaft fractures. Seven common surgical or non-surgical treatments, including reamed intramedullary nailing (RIN), un-reamed intramedullary nailing (UIN), minimally reamed intramedullary nailing (MIN), ender nailing (EN), external fixation (EF), plate, and cast, were compared, in terms of time to union, reoperation, non-union, malunion, infection and implant failure. Plate performed relatively better for time to union, while cast might be the best choice in close cases to reduce the risks of reoperation, non-union, malunion, and infection. To prevent implant failure, EN seemed to be better. Conclusion: Cast might have the highest probability of the most optimal choice for tibia shaft fracture in close cases, while reamed intramedullary nailing ranked second.

15.
Phys Rev Lett ; 122(8): 080501, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30932607

RESUMO

When a quantum system is driven slowly through a parametric cycle in a degenerate Hilbert space, the state would acquire a non-Abelian geometric phase, which is stable and forms the foundation for holonomic quantum computation (HQC). However, in the adiabatic limit, the environmental decoherence becomes a significant source of errors. Recently, various nonadiabatic holonomic quantum computation (NHQC) schemes have been proposed, but all at the price of increased sensitivity to control errors. Alternatively, there exist theoretical proposals for speeding up HQC by the technique of "shortcut to adiabaticity" (STA), but no experimental demonstration has been reported so far, as these proposals involve a complicated control of four energy levels simultaneously. Here, we propose and experimentally demonstrate that HQC via shortcut to adiabaticity can be constructed with only three energy levels, using a superconducting qubit in a scalable architecture. With this scheme, all holonomic single-qubit operations can be realized nonadiabatically through a single cycle of state evolution. As a result, we are able to experimentally benchmark the stability of STA+HQC against NHQC in the same platform. The flexibility and simplicity of our scheme makes it also implementable on other systems, such as nitrogen-vacancy center, quantum dots, and nuclear magnetic resonance. Finally, our scheme can be extended to construct two-qubit holonomic entangling gates, leading to a universal set of STAHQC gates.

16.
Adv Mater ; 31(19): e1808160, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30920702

RESUMO

Quantitatively mapping and monitoring the strain distribution in 2D materials is essential for their physical understanding and function engineering. Optical characterization methods are always appealing due to unique noninvasion and high-throughput advantages. However, all currently available optical spectroscopic techniques have application limitation, e.g., photoluminescence spectroscopy is for direct-bandgap semiconducting materials, Raman spectroscopy is for ones with Raman-active and strain-sensitive phonon modes, and second-harmonic generation spectroscopy is only for noncentrosymmetric ones. Here, a universal methodology to measure the full strain tensor in any 2D crystalline material by polarization-dependent third-harmonic generation is reported. This technique utilizes the third-order nonlinear optical response being a universal property in 2D crystals and the nonlinear susceptibility has a one-to-one correspondence to strain tensor via a photoelastic tensor. The photoelastic tensor of both a noncentrosymmetric D3h WS2 monolayer and a centrosymmetric D3d WS2 bilayer is successfully determined, and the strain tensor distribution in homogenously strained and randomly strained monolayer WS2 is further mapped. In addition, an atlas of photoelastic tensors to monitor the strain distribution in 2D materials belonging to all 32 crystallographic point groups is provided. This universal characterization on strain tensor should facilitate new functionality designs and accelerate device applications in 2D-materials-based electronic, optoelectronic, and photovoltaic devices.

17.
Nanoscale ; 11(13): 6480-6488, 2019 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-30892349

RESUMO

A30P and E46K are two mutants of α-synuclein (α-Syn) associated with familial early-onset Parkinson's disease (PD), and amyloid fibrils of α-Syn are the hallmarks of this disease. Detecting the heterogeneous system in the oligomerization stage of α-Syn is crucial for understanding the fibril formation and in vivo toxicity of α-Syn oligomers. Over the last two decades, solid-state nanopore technology has been developed into a reliable and versatile method in single-molecule studies. In this work, we study the time-dependent kinetics of early oligomerization of wild-type α-Syn, A30P, and E46K mutants through silicon nitride solid-state nanopores. By testing A30P, E46K, and wild-type α-Syn samples with different incubation times-from 3 to 15 days-we identify three typical types of oligomers formed in the oligomerization stage and confirm that A30P and E46K mutants aggregate faster than wild-type α-Syn. The results imply that the distinct aggregation pathways and kinetics featured by wild-type α-Syn and mutations may account for their distinct cytotoxicity and pathology in PD-related studies.


Assuntos
Amiloide/metabolismo , Nanoporos , alfa-Sinucleína/análise , Humanos , Microscopia Eletrônica de Transmissão , Doença de Parkinson/diagnóstico , Polimorfismo de Nucleotídeo Único , Compostos de Silício/química , alfa-Sinucleína/genética , alfa-Sinucleína/metabolismo
18.
Nanoscale ; 11(10): 4226-4230, 2019 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-30806651

RESUMO

Graphene quantum dots (GQDs), a zero-dimensional material system with distinct physical properties, have great potential in the applications of photonics, electronics, photovoltaics, and quantum information. In particular, GQDs are promising candidates for quantum computing. In principle, a sub-10 nm size is required for GQDs to present the intrinsic quantum properties. However, with such an extreme size, GQDs have predominant edges with lots of active dangling bonds and thus are not stable. Satisfying the demands of both quantum size and stability is therefore of great challenge in the design of GQDs. Herein we demonstrate the fabrication of sub-10 nm stable GQD arrays by embedding GQDs into large-bandgap hexagonal boron nitride (h-BN). With this method, the dangling bonds of GQDs were passivated by the surrounding h-BN lattice to ensure high stability, meanwhile maintaining their intrinsic quantum properties. The sub-10 nm nanopore array was first milled in h-BN using an advanced high-resolution helium ion microscope and then GQDs were directly grown in them through the chemical vapour deposition process. Stability analysis proved that the embedded GQDs show negligible property decay after baking at 100 °C in air for 100 days. The success in preparing sub-10 nm stable GQD arrays will promote the physical exploration and potential applications of this unique zero-dimensional in-plane quantum material.

19.
Phys Rev Lett ; 122(3): 036602, 2019 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-30735405

RESUMO

The quantum Hall effect (QHE) in a 3D Dirac semimetal thin film is attributed to either the quantum confinement induced bulk subbands or the Weyl orbits that connect the opposite surfaces via bulk Weyl nodes. However, it is still unknown whether the QHE based on the Weyl orbit can survive as the bulk Weyl nodes are gapped. Moreover, there are closed Fermi loops rather than open Fermi arcs on the Dirac semimetal surface, which can also host the QHE. Here we report the QHE in the 3D Dirac semimetal Cd_{3}As_{2} nanoplate by tuning the gate voltage under a fixed 30 T magnetic field. The quantized Hall plateaus at odd filling factors are observed as a magnetic field along the [001] crystal direction, indicating a Berry's phase π from the topological surface states. Furthermore, even filling factors are observed when the magnetic field is along the [112] direction, indicating the C_{4} rotational symmetry breaking and a topological phase transition. The results shed light on the understanding of QHE in 3D Cd_{3}As_{2}.

20.
Int Immunopharmacol ; 68: 226-233, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30660077

RESUMO

Rheumatoid arthritis (RA) is a chronic autoimmune disorder demanding the development of novel therapeutic strategy. Butyrate is a functional short-chain fatty acid produced by the anaerobic intestinal microbiota. This study aimed to investigate the attenuation of butyrate on RA. The collagen-induced arthritis (CIA) mouse model was established and butyrate was administered in drinking water along with the collagen immunization. The histopathological features, clinical score, paw swelling, as well as the production of pro-inflammatory cytokines including interleukin (IL)-1ß, IL-6 and IL-17A were measured to determine the amelioration of butyrate on arthritis. The differentiation of Treg cells and Th17 cells in the splenic cells was assessed by flow cytometry. The expression of Foxp3, IL-10, Rorγt and IL-17A were detected by RT-PCR and FACS immunostaining. Anti-IL10R antibody was used in the CIA and CD4+ cell cultures to mediate the effects of butyrate. Butyrate significantly inhibited expressions of IL-1ß, IL-6 and IL-17A, but promoted the expression of IL-10. Butyrate also increased systematical Treg cells and reduced Th17 cells. Mechanism study revealed that butyrate directly enhanced the polarization of Treg cells but not Th17 cells. All effects of butyrate on RA were inversed by the co-administered anti-IL10R antibody. This study showed that butyrate administration inhibited arthritis in CIA mice model, suppressed the expression of inflammatory cytokines. The modulation may be mediated the differentiation of CD4 T cells towards Treg cells, which produce anti-inflammatory cytokine IL-10, and thus influenced the function of Th17 cells.


Assuntos
Anti-Inflamatórios , Artrite Experimental , Artrite Reumatoide , Butiratos , Animais , Anti-Inflamatórios/farmacologia , Anti-Inflamatórios/uso terapêutico , Artrite Experimental/tratamento farmacológico , Artrite Experimental/imunologia , Artrite Experimental/patologia , Artrite Reumatoide/tratamento farmacológico , Artrite Reumatoide/imunologia , Artrite Reumatoide/patologia , Butiratos/farmacologia , Butiratos/uso terapêutico , Citocinas/imunologia , Feminino , Articulações do Pé/efeitos dos fármacos , Articulações do Pé/patologia , Camundongos Endogâmicos DBA , Linfócitos T Reguladores/efeitos dos fármacos , Linfócitos T Reguladores/imunologia , Células Th17/efeitos dos fármacos , Células Th17/imunologia
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