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1.
Nanoscale ; 11(48): 23498-23501, 2019 12 28.
Artigo em Inglês | MEDLINE | ID: mdl-31777899

RESUMO

Removal of expression of concern for 'Controllable 2H-to-1T' phase transition in few-layer MoTe2' by Yuan Tan et al., Nanoscale, 2018, 10, 19964-19971.

2.
Nanoscale ; 10(42): 19964-19971, 2018 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-30349910

RESUMO

Most two-dimensional (2D) transition metal dichalcogenides (TMDs) exhibit more than one structural phase, leading to a number of remarkable physics and potential device applications beyond graphene. Here, we demonstrated a feasible route to trigger 2H-to-1T' phase transition in few-layer molybdenum ditelluride (MoTe2) by laser irradiation. The effects of laser power and irradiation duration were systematically studied in this study, revealing the accumulated heating effect as the main driving force for such a phase transition. By carefully adjusting laser power and irradiation time, we could control the structural phases of MoTe2 as 2H, 2H + 1T', and 1T'. After thermal annealing at a rather low temperature, the laser-irradiated MoTe2 showed a completely suppressed 2H component and a more stabilized 1T' phase, demonstrating that the microscopic origin of the irreversible 2H-to-1T' phase transition is the formation of Te vacancies in MoTe2 due to laser local instantaneous heating. Our findings together with the unique properties of MoTe2 pave the way for high-performance nanoelectronics and optoelectronics based on 2D TMDs and their heterostructures.

3.
ACS Appl Mater Interfaces ; 10(36): 30045-30050, 2018 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-30146869

RESUMO

Growing uniform oxides with various thickness on TMDs is one of the biggest challenges to integrate TMDs into complementary metal oxide semiconductor (CMOS) logic circuits. Here, we report a layer-by-layer oxidation of atomically thin MoTe2 flakes via ozone (O3) exposure. The thickness of MoO x oxide film could be tuning with atomic-level accuracy simply by varying O3 exposure time. Additionally, MoO x-covered MoTe2 shows a hole-dominated transport behavior. Our findings point to a simple and effective strategy for growing homogeneous surface oxide film on MoTe2, which is promising for several purposes in metal-oxide-semiconductor transistor, ranging from surface passivation to dielectric layers.

4.
Nano Lett ; 18(2): 675-681, 2018 02 14.
Artigo em Inglês | MEDLINE | ID: mdl-29262252

RESUMO

Controllable synthesizing of one-dimensional-two-dimensional (1D-2D) heterostructures and tuning their atomic and electronic structures is nowadays of particular interest due to the extraordinary properties and potential applications. Here, we demonstrate the temperature-induced phase-controlled growth of 1D Mo6Te6-2D MoTe2 heterostructures via molecular beam epitaxy. In situ scanning tunneling microscopy study shows 2D ultrathin films are synthesized at low temperature range, while 1D nanowires gradually arise and dominate as temperature increasing. X-ray photoelectron spectroscopy confirms the good stoichiometry and scanning tunneling spectroscopy reveals the semimetallic property of grown Mo6Te6 nanowires. Through in situ annealing, a phase transition from 2D MoTe2 to 1D Mo6Te6 is induced, thus forming a semimetal-semiconductor junction in atomic level. An upward band bending of 2H-MoTe2 is caused by lateral hole injection from Mo6Te6. The work suggests a new route to synthesize 1D semimetallic transition metal chalcogenide nanowires, which could serve as ultrasmall conducting building blocks and enable band engineering in future 1D-2D heterostructure devices.

5.
Zhongguo Zhong Yao Za Zhi ; 42(18): 3578-3583, 2017 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-29218945

RESUMO

Drugs play the pharmacological effects by combining with target proteins. Identification of drug-target interactions is important for discovering new functions of drugs. In this paper, the target fingerprints based on molecular substructure and the drug-target similarity based on fingerprints are proposed to a random forest-based classification method, in order to identify the drug-target interactions. Experiments on enzymes, ion channels, G protein-coupled receptors and nuclear receptors proved the effectiveness of the proposed method. In addition, the proposed method is applied to predict the interactions between ingredients and targets of traditional Chinese medicines.


Assuntos
Interações de Medicamentos , Enzimas/metabolismo , Canais Iônicos/metabolismo , Receptores Citoplasmáticos e Nucleares/metabolismo , Receptores Acoplados a Proteínas-G/isolamento & purificação , Medicina Tradicional Chinesa
6.
Huan Jing Ke Xue ; 38(8): 3185-3191, 2017 Aug 08.
Artigo em Chinês | MEDLINE | ID: mdl-29964925

RESUMO

Snow samples were collected from the snow event on January 20-22, 2016 from 11 sites in downtown Hangzhou to explore the occurrence of sixteen perfluorinated compounds (PFCs) in the atmosphere. All samples were prepared by solid-phase extraction with Oasis WAX cartridges and analyzed using ultra performance liquid chromatography interfaced with tandem mass spectrometry (UPLC-MS/MS). The results showed that seven medium- and short-chain PFCs including C4 and C8 perfluorinated sulfonates (PFSAs) and C4-C6, C8, and C9 perfluorinated carboxylic acids (PFCAs) were detected in the snow samples. Total PFC concentrations ranged from 2.85 to 35.1 ng·L-1, whereas perfluorooctanoic acid (PFOA) dominated, with ranges of 2.15-23.0 ng·L-1, and perfluorooctane sulfonate (PFOS) was detected at lower levels, ranging from 0 to 0.46 ng·L-1. As compared to the results from other studies, the PFOA concentrations of the study region were at mid-level and the PFOS concentrations were relatively low. The spatial distribution of PFCs varied, and the pollutant concentrations of the snow samples from the sampling sites located in the urban areas were higher than those in the rural areas. The greatest total PFC concentrations were detected in Fuyang, whereas the lowest concentrations were detected in Jiande and Chun'an. In this study, the high concentrations of PFCs dominated by PFOA that were measured in the Hangzhou snow samples emphasize the importance of atmospheric wet deposition as one of the sources of PFC contamination in this ecological system and should be addressed. The occurrence of PFCs in the air, indicated by their presence in the snow, suggests that the atmospheric environment may be an important contributor in human and ecological exposure to PFCs by local residents.

7.
Sci Rep ; 5: 12198, 2015 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-26195033

RESUMO

A so called all-carbon based graphene field effect transistor (GFET) in which the electrodes are composed of graphite-like nano-sheets instead of metals in the traditional devices is fabricated by one-step e-beam direct writing (EBDW). It is also found that the graphite-like nano-sheets in electrodes are perpendicular to the channel graphene, which is confirmed by the transmission electron microscopy (HRTEM). The one-step fabrication of the carbonaceous electrodes is more convenient and lower-cost comparing to the preparation of traditional metal electrodes and can be applied to many other nano-electronic devices.

8.
Huan Jing Ke Xue ; 36(12): 4471-8, 2015 Dec.
Artigo em Chinês | MEDLINE | ID: mdl-27011982

RESUMO

This study studied the pollution characteristics of perfluorinated compounds (PFCs) in Qiantang River in Hangzhou section (QR). Surface water samples, collected in July 2014 and January 2015 from 14 sites in QR were analyzed for 16 PFCs. All samples were prepared by solid-phase extraction with Oasis WAX cartridges and analyzed using the ultra performance liquid chromatography interfaced to tandem mass spectrometry ( UPLC-MS/MS). The results showed that 8 medium-and short-chain PFCs including C4 and C8 perfluorinated sulfonates (PFSAs) and C4-C9 perfluorinated carboxylic acids (PFCAs) were detected in the surface waters. The total concentrations of PFCs ranged from 0.98 to 609 ng · L⁻¹, while perfluorooctanoic acid (PFOA) dominated, with range of 0.59-538 ng L⁻¹, and perfluorooctane sulfonate (PFOS) was detected at lower levels, ranging from 0 to 2.48 ng · L⁻¹. The spatial distribution of PFCs varied, and the pollutant concentrations at the sampling sites located in upstream of the river such as Lanjiangkou and Jiangjunyan were relatively high, PFCs concentration showed a decreasing trend from the upstream to the downstream. According to the ratio of feature components, PFCs in surface water of QR originated largely from the input of direct sewage emissions. Taken together, the PFCs pollution was highly correlated with the upstream of Qiantang River valley's industry distribution, and most of the mass load in the investigated river was attributed to upstream running water with a minor influence from the wastewater discharges along the river basin. Overall, the results presented here indicated that greater attention should be given to the contamination of PFCs, especially for PFOA in water body of QR.


Assuntos
Ácidos Alcanossulfônicos/análise , Caprilatos/análise , Fluorcarbonetos/análise , Rios/química , Poluentes Químicos da Água/análise , Ácidos Carboxílicos , China , Cromatografia Líquida de Alta Pressão , Monitoramento Ambiental , Extração em Fase Sólida , Espectrometria de Massas em Tandem , Águas Residuárias , Água
9.
Se Pu ; 32(5): 472-6, 2014 May.
Artigo em Chinês | MEDLINE | ID: mdl-25185306

RESUMO

A high-throughput detection method has been developed for the determination of sixteen perfluorinated organic compounds (PFCs) in surface water by solid phase extraction-ultra performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (SPE-UPLC-ESI-MS/MS). The water samples were concentrated and purified through WAX solid phase extraction cartridges. The UPLC separation was performed on an ACQUITY UPLC BEH C18 column utilizing a gradient elution program of methanol (containing 2 mmol/L ammonium acetate) and water (containing 2 mmol/L ammonium acetate) as the mobile phases at a flow rate of 0.4 mL/min. The MS/MS detection was performed under negative electrospray ionization ( ESI ) in multiple reaction monitoring (MRM) mode. Good linearities were observed in the range of 0.5-100 gg/L or 1.0 - 100 microg/L with correlation coefficients from 0.998 7 to 0.999 9. The limits of detection (LODs) for the sixteen perfluorinated organic compounds were in the range of 0.06-0.46 ng/L. The recoveries ranged from 67.6% to 103% with the relative standard deviations between 2.94% and 12.0%. This method was characterized by high sensitivity and precision, extensive range and high speed, and can be applied for the analysis of PFC contaminants in surface water.

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