Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 30
Filtrar
Mais filtros








Base de dados
Intervalo de ano de publicação
1.
Nat Prod Res ; : 1-8, 2024 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-38427608

RESUMO

Female germline stem cells (FGSCs) are renewable sources of oocytes that play an indispensable role in re-establishing mammal fertility. Here, we have established FGSCs from neonatal mice, which exhibit characteristics of germline stem cells. We show that compared with monomeric trigonelline and diosgenin, macromolecular compounds Cistanche deserticola polysaccharides (CDPs) in Chinese herbal medicine can enhance the ability of FGSCs to differentiate into oocytes at appropriate concentrations while maintaining self-renewal in vitro. In contrast, trigonelline and diosgenin inhibited the expression of germ cell-specific genes while reducing cell proliferation activity. In summary, CDPs could induce the differentiation and self-renewal of FGSCs in vitro. The comparison of the effects of the active components of different types of Chinese medicine will provide a reference for the development of clinical drugs in the future, and help to elucidate the development process of FGSCs.

2.
Environ Sci Pollut Res Int ; 30(43): 96875-96890, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37581730

RESUMO

In this work, a Z-scheme LaFeO3/g-C3N4/ZnO heterojunction photocatalyst with large specific surface (68.758 m2/g) and low cost (0.00035 times the cost of per gram of Au) was easily synthesized by glucose-assisted hydrothermal method. The structure, surface morphology, and optical properties of the photocatalyst were investigated. The constructed Z-scheme heterojunction catalysts can enhance the visible light absorption and carrier separation efficiency. Among these photocatalysts, the 10%-LaFeO3/g-C3N4/ZnO composite possesses the premium performance for efficient degrading 97.43% of phenol within 120 min. Even after 5 cycles, it still sustains an excellent photocatalytic stability (92.13% phenol degradation). According to the XPS surface states and the capture of active species on LaFeO3/g-C3N4/ZnO, the electrons would be transferred from ZnO and LaFeO3 to g-C3N4. In addition, ·OH plays an important role in photocatalytic reactions for phenol degradation. Thus, the proposed possible photocatalytic reaction mechanism of Z-scheme LaFeO3/g-C3N4/ZnO can provide a more economical and efficient conception for phenol degradation.


Assuntos
Óxido de Zinco , Elétrons , Luz , Fenóis
3.
Nat Commun ; 14(1): 3075, 2023 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-37244900

RESUMO

Copper-based catalyst is uniquely positioned to catalyze the hydrocarbon formations through electrochemical CO2 reduction. The catalyst design freedom is limited for alloying copper with H-affinitive elements represented by platinum group metals because the latter would easily drive the hydrogen evolution reaction to override CO2 reduction. We report an adept design of anchoring atomically dispersed platinum group metal species on both polycrystalline and shape-controlled Cu catalysts, which now promote targeted CO2 reduction reaction while frustrating the undesired hydrogen evolution reaction. Notably, alloys with similar metal formulations but comprising small platinum or palladium clusters would fail this objective. With an appreciable amount of CO-Pd1 moieties on copper surfaces, facile CO* hydrogenation to CHO* or CO-CHO* coupling is now viable as one of the main pathways on Cu(111) or Cu(100) to selectively produce CH4 or C2H4 through Pd-Cu dual-site pathways. The work broadens copper alloying choices for CO2 reduction in aqueous phases.

4.
Sci Total Environ ; 883: 163635, 2023 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-37100146

RESUMO

Compared to traditional mechanical brownfield remediation strategies, phytoremediation as a sustainable and low-impact solution, yielding long-term soil chemical improvement. As a common part of many local plant communities, spontaneous invasive plants have advantages over native species in growth speed and resource-use efficiency and are many are effective on degrading or removing chemical soil pollutants. This research presents a methodology for using spontaneous invasive plants as the agent of phytoremediation for brownfield remediation is an innovative component of ecological restoration and design. This research explores s conceptual and applicable model of using spontaneous invasive plants in the phytoremediation of brownfield soil for environmental design practice. This research summarizes five parameters (Soil Drought Level, Soil Salinity, Soil Nutrients, Soil Metal Pollution, and Soil pH) and their classification standards. Based on the five parameters, a series of experiments were designed to examine 5 spontaneous invasive species' tolerance and performance to different soil conditions. Taking the research results as a data base, this research developed a conceptual model of selecting suitable spontaneous invasive plants for brownfield phytoremediation by overlaying the soil condition data and plants' tolerance data. Using a brownfield site in Boston metropolitan region as a case study, the research tested the feasibility and rationality of this model. The results propose a novel approach and materials for general environmental remediation of contaminated soil by involving spontaneous invasive plants. It also transforms the abstract phytoremediation knowledge and data to an applicable model which integrates and visualizes the requirements of scientific plant selection, design aesthetic, and ecosystem factors to help the environmental design process in brownfield remediation.


Assuntos
Recuperação e Remediação Ambiental , Poluentes do Solo , Biodegradação Ambiental , Ecossistema , Solo , Metais , Poluentes do Solo/análise , Plantas
5.
Int J Biol Sci ; 18(14): 5369-5390, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36147461

RESUMO

The incidence of cholangiocarcinoma (CCA) has been increasing over the past few years. Although there are surgery, chemotherapy and other conventional treatment methods, the effect is not as expected. At present, immunotherapy has become the research frontier of cancer treatment, and CCA tumor microenvironment (TME) is becoming a hot exploration direction of immunobiology. TME can affect tumor progression through changes in metabolism, secretion and immunity. Accordingly, understanding the role played by immune cells and stromal cells in TME is important for the study of CCA immunotherapy. This review will discuss the interactions between immune cells (including CD8+ T cells, CD4+ T cells, macrophages, natural killer cells, dendritic cells, myeloid suppressor cells, mast cells, and neutrophils) and stromal cells (including cancer-associated fibroblasts, endothelial cells) in the TME of CCA. In addition, we will also discuss current research results on TME of CCA and recent advances in immunotherapy.


Assuntos
Neoplasias dos Ductos Biliares , Colangiocarcinoma , Neoplasias , Neoplasias dos Ductos Biliares/patologia , Neoplasias dos Ductos Biliares/terapia , Ductos Biliares Intra-Hepáticos/metabolismo , Ductos Biliares Intra-Hepáticos/patologia , Linfócitos T CD8-Positivos , Colangiocarcinoma/patologia , Colangiocarcinoma/terapia , Células Endoteliais/metabolismo , Humanos , Imunoterapia , Neoplasias/metabolismo , Microambiente Tumoral
6.
J Ethnopharmacol ; 296: 115513, 2022 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-35779819

RESUMO

ETHNOPHARMACOLOGICAL RELEVANCE: Pneumonia is common and frequently-occurred disease caused by pathogens which predisposes to lung parenchymal inflammation leading pulmonary dysfunction. To prevent and alleviate the symptoms of pneumonia, Qinggan Yin formula (QGY) was composed based on clinical experience and four classical traditional Chinese medicine prescriptions which frequently applied to treat infectious diseases. AIM OF THE STUDY: Traditional Chinese medicine is a complex mixture and it is difficult to distinguish the effective component molecules. The aim of this study is to identify the compounds of QGY with anti-inflammatory effects and investigate the molecular mechanism. MATERIALS AND METHODS: The high-resolution mass spectrometry and molecular networking were performed for comprehensive chemical profiling of QGY. Network pharmacology was used to generate "herbal-target-pathway" network for target predictions. The anti-inflammation effects of QGY were evaluated in mice model of lipopolysaccharide (LPS) induced acute inflammation. Tail transected zebrafish was also employed to validate macrophage migration reversed effect of QGY. Based on the molecular enrichment analysis, the active substances of QGY with anti-inflammatory effects were further identified in cellular model of macrophage activation. The mechanisms of active substances were investigated by testing their effects on the expression of correlated proteins by Western blot. RESULTS: In total, 71 compounds are identified as major substances of QGY. According to the results of network pharmacology, QGY shows moderate anti-inflammatory effects and inhibit pulmonary injury. MAPK signaling pathway was predicted as the most related pathway regulated by QGY. Moreover, QGY significantly inhibit LPS-induced pulmonary inflammation in mice, and reversed macrophage migration toward the injury site in zebrafish. We also validate that some major compounds in QGY significantly attenuated the release of IL-1ß, IL-6 and TNF-α in LPS-stimulated macrophage. Those active substances including acacetin and arctiin can inhibit the phosphorylation of ERK/JNK and down-regulated the protein expression of BCL-2. CONCLUSION: Collectively, QGY possessed pronounced anti-inflammation effects. The integration of network pharmacology and experimental results indicated arctiin, iridin, acacetin, liquiritin, and arctigenin are major active substances of QGY with anti-inflammatory effects. The underlying mechanism of QGY involves MAPK signaling pathway and oxidative stress pathway.


Assuntos
Medicamentos de Ervas Chinesas , Pneumonia , Animais , Anti-Inflamatórios/farmacologia , Anti-Inflamatórios/uso terapêutico , Medicamentos de Ervas Chinesas/farmacologia , Medicamentos de Ervas Chinesas/uso terapêutico , Flavonoides , Lipopolissacarídeos/toxicidade , Camundongos , Farmacologia em Rede , Pneumonia/induzido quimicamente , Pneumonia/tratamento farmacológico , Peixe-Zebra
7.
Cell Rep ; 38(13): 110559, 2022 03 29.
Artigo em Inglês | MEDLINE | ID: mdl-35354039

RESUMO

Host genes critical for viral infection are effective antiviral drug targets with tremendous potential due to their universal characteristics against different subtypes of viruses and minimization of drug resistance. Accordingly, we execute a genome-wide CRISPR-Cas9 screen with multiple rounds of survival selection. Enriched in this screen are several genes critical for host sialic acid biosynthesis and transportation, including the cytohesin 2 (CYTH2), tetratricopeptide repeat protein 24 (TTC24), and N-acetylneuraminate synthase (NANS), which we confirm are responsible for efficient influenza viral infection. Moreover, we reveal that CYTH2 is required for the early stage of influenza virus infection by mediating endosomal trafficking. Furthermore, CYTH2 antagonist SecinH3 blunts influenza virus infection in vivo. In summary, these data suggest that CYTH2 is an attractive target for developing host-directed antiviral drugs and therapeutics against influenza virus infection.


Assuntos
Vírus da Influenza A , Influenza Humana , Antivirais/farmacologia , Sistemas CRISPR-Cas/genética , Endossomos , Humanos , Vírus da Influenza A/genética , Influenza Humana/tratamento farmacológico , Influenza Humana/genética
8.
Molecules ; 26(11)2021 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-34071835

RESUMO

Water-soluble cellulose ethers are widely used as stabilizers, thickeners, and viscosity modifiers in many industries. Understanding rheological behavior of the polymers is of great significance to the effective control of their applications. In this work, a series of cyanoethylcellulose (CEC) samples with different molecular weights were prepared with cellulose and acrylonitrile in NaOH/urea aqueous solution under the homogeneous reaction. The rheological properties of water-soluble CECs as a function of concentration and molecular weight were investigated using shear viscosity and dynamic rheological measurements. Viscoelastic behaviors have been successfully described by the Carreau model, the Ostwald-de-Waele equation, and the Cox-Merz rule. The entanglement concentrations were determined to be 0.6, 0.85, and 1.5 wt% for CEC-11, CEC-7, and CEC-3, respectively. All of the solutions exhibited viscous behavior rather than a clear sol-gel transition in all tested concentrations. The heterogeneous nature of CEC in an aqueous solution was determined from the Cox-Merz rule due to the coexistence of single chain complexes and aggregates. In addition, the CEC aqueous solutions showed good thermal and time stability, and the transition with temperature was reversible.

9.
J Ethnopharmacol ; 277: 114201, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34015365

RESUMO

ETHNOPHARMACOLOGICAL RELEVANCE: Compound Agrimony Enteritis Capsules (FFXHC) is an ethnomedicine derived from Yi Nationality Herbal Medicine for the treatment of enteritis. We found that compared to berberine hydrochloride (BBR), a component of this medicine, FFXHC was more efficacious in the mouse model of IC mice in significantly alleviating lung and intestinal lesions. " Our study provides a novel perspective into the pharmacological mechanism of action of the ethnic compound FFXHC. AIM OF THE STUDY: To determine the underlying mechanism of the superiority of FFXHC over BBR in IC. MATERIALS AND METHODS: The susceptibility of Candida albicans to FFXHC was evaluated in vitro. The mouse model of IC was established and the survival rate, weight change, the number of organ colonies, and immune organ coefficient of the mice were determined, the effect of FFXHC on the immune function of mice, including changes in the number of immune cells, levels of the related inflammatory cytokines (INF-γ, TNF-α, MCP-1, IL-6, and IL-17A), and the antimicrobial peptide, LL-37 (CRAMP in mice), were determined. Mice feces were collected and changes in the intestinal microecology were studied. RESULTS: Our findings indicated that FFXHC was not active against Candida albicans and did not restore the sensitivity of the resistant strain in vitro; however, it had a therapeutic effect that improve survival rate on mice with IC. The number of lymphocytes and neutrophils of mice with IC treated with FFXHC increased significantly. The intestinal microecology of mice was restored and the abundance of the probiotic Bacteroides was increased, which further stimulated the production of the antimicrobial peptide, LL-37, which is required for acquired immunity. Furthermore, the levels of Th cell-related cytokines, including INF-γ, TNF-α, and IL-17A were significantly increased, whereas those of the proinflammatory cytokines, IL-6 and MCP-1, decreased. With the activation of acquired immunity, the immune function of mice was restored, the body weight and survival rate of mice improved considerably, the coefficients of the thymus and spleen increased, and the number of fungal colonies in the lung and kidney decreased. CONCLUSIONS: FFXHC could eliminate fungi by increasing the relative abundance of probiotics in Bacteroides and the number of neutrophils, thereby promoting the production of CRAMP and resulting in a fungicidal effect, leading to acquired immunity. Although BBR has an antifungal effect, we found that it was not as effective as FFXHC.


Assuntos
Berberina/farmacologia , Candida albicans/efeitos dos fármacos , Candidíase Invasiva/tratamento farmacológico , Medicamentos de Ervas Chinesas/farmacologia , Animais , Antifúngicos/isolamento & purificação , Antifúngicos/farmacologia , Berberina/isolamento & purificação , Candidíase Invasiva/microbiologia , Cápsulas , Modelos Animais de Doenças , Medicamentos de Ervas Chinesas/química , Feminino , Masculino , Medicina Tradicional Chinesa , Camundongos , Camundongos Endogâmicos BALB C , Probióticos/metabolismo , Taxa de Sobrevida
10.
Front Microbiol ; 11: 572608, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33178156

RESUMO

Candida albicans is a ubiquitous clinical fungal pathogen. Prolonged use of the first-line antifungal agent fluconazole (FLC) has intensified fungal resistance and limited its effectiveness for the treatment of fungal infections. The combined administration of drugs has been extensively studied and applied. SWL-1 is a lignin compound derived from the Traditional Chinese Medicine Schisandra chinensis. In this study, we show that SWL-1 reverses resistance to fluconazole in C. albicans when delivered in combination, with a sharp decrease in the IC50 of fluconazole from >200 to 3.74 ± 0.25 µg/ml, and also reverses the fluconazole resistance of C. albicans in vitro, with IC50 from >200 to 5.3 ± 0.3 µg/ml. Moreover, killing kinetics curves confirmed the synergistic effects of fluconazole and SWL-1. Intriguingly, when SWL-1 was administered in combination with fluconazole in a mouse model of systemic infection, the mortality of mice was markedly decreased and fungal colonization of the kidney and lung was reduced. Further mechanistic studies showed that SWL-1 significantly decreased intracellular adenosine 5'-triphosphate (ATP) levels and inhibited the function of the efflux pump responsible for fluconazole resistance of C. albicans. Proteomic analysis of the effects of SWL-1 on C. albicans showed that several enzymes were downregulated in the glycolytic pathway. We speculate that SWL-1 significantly decreased intracellular ATP levels by hindering the glycolysis, and the function of the efflux pump responsible for fluconazole resistance of C. albicans was inhibited, resulting in restoration of fluconazole sensitivity in FLC-resistant C. albicans. This study clarified the effects and mechanism of SWL-1 on C. albicans in vitro and in vivo, providing a novel approach to overcoming fungal resistance.

11.
Small ; 16(34): e2002263, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32696555

RESUMO

2D transition metal dichalcogenides (TMDs) have exhibited strong application potentials in new emerging electronics because of their atomic thin structure and excellent flexibility, which is out of field of tradition silicon technology. Similar to 3D p-n junctions, 2D p-n heterojunctions by laterally connecting TMDs with different majority charge carriers (electrons and holes), provide ideal platform for current rectifiers, light-emitting diodes, diode lasers and photovoltaic devices. Here, growth and electrical studies of atomic thin high-quality p-n heterojunctions between molybdenum diselenide (MoSe2 ) and tungsten diselenide (WSe2 ) by one-step chemical vapor deposition method are reported. These p-n heterojunctions exhibit high built-in potential (≈0.7 eV), resulting in large current rectification ratio without any gate control for diodes, and fast response time (≈6 ms) for self-powered photodetectors. The simple one-step growth and electrical studies of monolayer lateral heterojunctions open up the possibility to use TMD heterojunctions for functional devices.

12.
Nano Lett ; 19(10): 6765-6771, 2019 10 09.
Artigo em Inglês | MEDLINE | ID: mdl-31545901

RESUMO

Interfacial quantum states are drawing tremendous attention recently because of their importance in design of low-dimensional quantum heterostructures with desired charge, spin, or topological properties. Although most studies of the interfacial exchange interactions were mainly performed across the interface vertically, the lateral transport nowadays is still a major experimental method to probe these interactions indirectly. In this Letter, we fabricated a graphene and hydrogen passivated silicon interface to study the interfacial exchange processes. For the first time we found and confirmed a novel interfacial quantum state, which is specific to the 2D-3D interface. The vertically propagating electrons from silicon to graphene result in electron oscillation states at the 2D-3D interface. A harmonic oscillator model is used to explain this interfacial state. In addition, the interaction between this interfacial state (discrete energy spectrum) and the lateral band structure of graphene (continuous energy spectrum) results in Fano-Feshbach resonance. Our results show that the conventional description of the interfacial interaction in low-dimensional systems is valid only in considering the lateral band structure and its density-of-states and is incomplete for the ease of vertical transport. Our experimental observation and theoretical explanation provide more insightful understanding of various interfacial effects in low-dimensional materials, such as proximity effect, quantum tunneling, etc. More important, the Fano-Feshbach resonance may be used to realize all solid-state and scalable quantum interferometers.

13.
Mol Immunol ; 114: 133-138, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31352229

RESUMO

Canine distemper is a highly contagious disease of wild and domestic carnivores. Obtaining of a suitable cell line for canine distemper virus (CDV) propagation is very important for field CDV isolation and vaccine antigen preparation. However, the cell line currently developed cell lines for CDV propagation are a marmoset lymphoid cell line (B95a), which could cause the virus to potentially infect human cells, and canine SLAM-expressing Vero cells, which may cause the virus to lose virulence. Therefore, a canine cell line constructed for efficient CDV propagation would be attractive. In the present study, a Madin-Darby Canine Kidney Epithelial (MDCK) cell line with mavs (mitochondrial antiviral signaling) inactivation was constructed by CRISPR/Cas9 technology. The interferon-I response induced by poly(I:C), an analogue of viral RNA, was significantly blocked in the constructed cell line, designated MDCK-KOmavs. Moreover, the propagation of a filed CDV strain was approximately 100 times higher in MDCK-KOmavs cells than in wild-type MDCK cells. Therefore, in the present study, a canine cell line facilitating CDV propagation was successfully constructed, and the results suggested that the constructed canine cell line was more efficient than the wild-type cell line for the isolation of field CDVs. In addition, the rapid propagation of CDVs to high titers in the constructed MDCK-KOmavs cell line indicated that this cell line could also be an alternative cell line for the preparation of vaccine antigens.


Assuntos
Vírus da Cinomose Canina/genética , Animais , Antígenos CD/genética , Sistemas CRISPR-Cas/genética , Linhagem Celular , Chlorocebus aethiops , Cinomose/genética , Cães , Humanos , Células Madin Darby de Rim Canino , Células Vero
14.
J Hazard Mater ; 377: 195-205, 2019 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-31163348

RESUMO

A series of catalysts with p-LaFeO3/n-ZnO heterostructure were designed and prepared by hydrothermal method. The structure, surface topographies, optical properties and interfacial interactions of these photocatalysts were analyzed by XRD, SEM, TEM, PL, Uv-vis DRS, XPS, COD, TOC etc., indicating that p-n heterojunction formed at the interface between p-LaFeO3 and n-ZnO, which enhanced the photocatalytic activity. Among them, the 20%-p-LaFeO3/n-ZnO composite exhibits the best activity for the phenol degradation under visible light. The superior photocatalytic activity of the heterojunction photocatalyst is mainly attributed to the formation of p-n heterojunction which leads to an efficient separation of photogenerated electron-hole pairs. Besides, the 20%-p-LaFeO3/n-ZnO heterojunction photocatalyst shows the excellent photocatalytic stability after 4 cycles. And from the free radical capture experiment, the degradation of phenol is dominated by the oxidation reaction of hydroxyl radicals and direct hole oxidation. What's more, certain intermediates were detected by HPLC and 3D-EEMs. Therefore, a photocatalytic mechanism of the 20%-p-LaFeO3/n-ZnO p-n heterojunction catalyst for phenol degradation under visible light irradiation was proposed.

15.
ACS Appl Mater Interfaces ; 11(13): 12777-12785, 2019 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-30854848

RESUMO

Metal-semiconductor contact has been a critical topic in the semiconductor industry because it influences device performance remarkably. Conventional metals have served as the major contact material in electronic and optoelectronic devices, but such a selection becomes increasingly inadequate for emerging novel materials such as two-dimensional (2D) materials. Deposited metals on semiconducting 2D channels usually form large resistance contacts due to the high Schottky barrier. A few approaches have been reported to reduce the contact resistance but they are not suitable for large-scale application or they cannot create a clean and sharp interface. In this study, a chemical vapor deposition (CVD) technique is introduced to produce large-area semiconducting 2D material (2H MoTe2) planarly contacted by its metallic phase (1T' MoTe2). We demonstrate the phase-controllable synthesis and systematic characterization of large-area MoTe2 films, including pure 2H phase or 1T' phase, and 2H/1T' in-plane heterostructure. Theoretical simulation shows a lower Schottky barrier in 2H/1T' junction than in Ti/2H contact, which is confirmed by electrical measurement. This one-step CVD method to synthesize large-area, seamless-bonding 2D lateral metal-semiconductor junction can improve the performance of 2D electronic and optoelectronic devices, paving the way for large-scale 2D integrated circuits.

16.
Nucleic Acids Res ; 47(7): 3568-3579, 2019 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-30698806

RESUMO

Argonaute proteins are present and conserved in all domains of life. Recently characterized prokaryotic Argonaute proteins (pAgos) participates in host defense by DNA interference. Here, we report that the Natronobacterium gregoryi Argonaute (NgAgo) enhances gene insertions or deletions in Pasteurella multocida and Escherichia coli at efficiencies of 80-100%. Additionally, the effects are in a homologous arms-dependent but guide DNA- and potential enzyme activity-independent manner. Interestingly, such effects were also observed in other pAgos fragments including Thermus thermophilus Argonaute (TtAgo), Aquifex aeolicus Argonaute (AaAgo) and Pyrococcus furiosus Argonaute (PfAgo). The underlying mechanism of the NgAgo system is a positive selection process mainly through its PIWI-like domain interacting with recombinase A (recA) to enhance recA-mediated DNA strand exchange. Our study reveals a novel system for enhancing homologous sequence-guided gene editing in bacteria.


Assuntos
Proteínas Argonautas/genética , DNA Bacteriano/genética , Recombinação Homóloga/genética , Homologia de Sequência , Escherichia coli/genética , Edição de Genes , Natronobacterium/genética , Células Procarióticas , Pyrococcus furiosus/genética , Thermus thermophilus/genética
17.
ACS Nano ; 12(12): 12571-12577, 2018 Dec 26.
Artigo em Inglês | MEDLINE | ID: mdl-30481003

RESUMO

Two-dimensional (2D) van der Waals layered materials possess innate advantages as integrable sensors, due to their thinness, flexibility, and sensitivity. They can be seamlessly integrated onto surfaces with different geometries where detection for near-field signal is desired. In this study, we develop a device transfer technique to integrate device assemblies based on 2D materials onto an arbitrary smooth surface. Such technique utilizes a sacrificial polymer underlayer and achieves clean and nondestructive full device transfer. For demonstration, we transferred a complete 2D multilayer InSe photodetector device onto a stripped optical fiber. Due to the extreme vicinity of the 2D photodetector with the fiber core, the device can effectively couple with the evanescent field and accurately detect information transmitted inside the optical fiber. In addition, these super thin flexible device assemblies can be integrated onto the fibers themselves to non-invasively monitor the optical fiber performance. The demonstration of optically coupled, conformal 2D devices on substrates of different form factors can enable a variety of near-field optical and sensing applications.

18.
Adv Mater ; 30(45): e1804218, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30198162

RESUMO

Composition and phase specific 2D transition metal dichalogenides (2D TMDs) with a controlled electronic and chemical structure are essential for future electronics. While alloying allows bandgap tunability, heterostructure formation creates atomically sharp electronic junctions. Herein, the formation of lateral heterostructures from quaternary 2D TMD alloys, by thermal annealing, is demonstrated. Phase separation is observed through photoluminescence and Raman spectroscopy, and the sharp interface of the lateral heterostructure is examined via scanning transmission electron microscopy. The composition-dependent transformation is caused by existence of miscibility gap in the quaternary alloys. The phase diagram displaying the miscibility gap is obtained from the reciprocal solution model based on density functional theory and verified experimentally. The experiments show direct evidence of composition-driven heterostructure formation in 2D atomic layer systems.

19.
Nano Lett ; 18(2): 682-688, 2018 02 14.
Artigo em Inglês | MEDLINE | ID: mdl-29300487

RESUMO

Vertical integration of van der Waals (vdW) materials with atomic precision is an intriguing possibility brought forward by these two-dimensional (2D) materials. Essential to the design and analysis of these structures is a fundamental understanding of the vertical transport of charge carriers into and across vdW materials, yet little has been done in this area. In this report, we explore the important roles of single layer graphene in the vertical tunneling process as a tunneling barrier. Although a semimetal in the lateral lattice plane, graphene together with the vdW gap act as a tunneling barrier that is nearly transparent to the vertically tunneling electrons due to its atomic thickness and the transverse momenta mismatch between the injected electrons and the graphene band structure. This is accentuated using electron tunneling spectroscopy (ETS) showing a lack of features corresponding to the Dirac cone band structure. Meanwhile, the graphene acts as a lateral conductor through which the potential and charge distribution across the tunneling barrier can be tuned. These unique properties make graphene an excellent 2D atomic grid, transparent to charge carriers, and yet can control the carrier flux via the electrical potential. A new model on the quantum capacitance's effect on vertical tunneling is developed to further elucidate the role of graphene in modulating the tunneling process. This work may serve as a general guideline for the design and analysis of vdW vertical tunneling devices and heterostructures, as well as the study of electron/spin injection through and into vdW materials.

20.
Adv Sci (Weinh) ; 4(9): 1700076, 2017 09.
Artigo em Inglês | MEDLINE | ID: mdl-28932666

RESUMO

Graphene/hexagonal boron nitride (h-BN) monolayer in-plane heterostructure offers a novel material platform for both fundamental research and device applications. To obtain such a heterostructure in high quality via controllable synthetic approaches is still challenging. In this work, in-plane epitaxy of graphene/h-BN heterostructure is demonstrated on Cu-Ni substrates. The introduction of nickel to copper substrate not only enhances the capability of decomposing polyaminoborane residues but also promotes graphene growth via isothermal segregation. On the alloy surface partially covered by h-BN, graphene is found to nucleate at the corners of the as-formed h-BN grains, and the high growth rate for graphene minimizes the damage of graphene-growth process on h-BN lattice. As a result, high-quality graphene/h-BN in-plane heterostructure with epitaxial relationship can be formed, which is supported by extensive characterizations. Photodetector device applications are demonstrated based on the in-plane heterostructure. The success will have important impact on future research and applications based on this unique material platform.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA