Showing papers by "Dong Wang published in 2018"
TL;DR: The results reveal the chemistry of BP degradation and provide a practical approach for exfoliation, delivery, and application of BP and show that BP reacts with oxygen in water even without light illumination.
Abstract: Exfoliated black phosphorus (BP), as a monolayer or few-layer material, has attracted tremendous attention owing to its unique physical properties for applications ranging from optoelectronics to photocatalytic hydrogen production. Approaching intrinsic properties has been, however, challenged by chemical reactions and structure degradation of BP under ambient conditions. Surface passivation by capping agents has been proposed to extend the processing time window, yet contamination or structure damage rise challenges for BP applications. Here, we report experiments combined with first-principle calculations that address the degradation chemistry of BP. Our results show that BP reacts with oxygen in water even without light illumination. The reaction follows a pseudo-first-order parallel reaction kinetics, produces PO23–, PO33–, and PO43– with reaction rate constants of 0.019, 0.034, and 0.023 per day, respectively, and occurs preferentially from the P atoms locating at BP edges, which yields structural de...
239 citations
TL;DR: On the basis of the freestanding COF films, a nanofilter membrane and photoelectrochemical sensors for Ru3+ were successfully developed and the strategy was extended to the synthesis of crystalline zeolitic imidazolate framework-8 thin film, which exhibited high application potential.
Abstract: The confined synthesis of two-dimensional covalent organic framework (2D COF) thin films was developed by using thin superspreading water on the hydrogel immersed under oil as reactor. Through loading two monomers into oil and hydrogel, respectively, COF thin films are synthesized at the oil/water/hydrogel interface. This strategy provides a new way for synthesis of freestanding 2D COF thin films. Detailed characterizations of the COF thin films reveal homogeneous topography, large area, controllable thickness from 4 to 150 nm, and crystallinity with certain orientation. Young’s modulus of COF film is measured by AFM indentation as 25.9 ± 0.6 GPa, showing good mechanical properties. On the basis of the freestanding COF films, a nanofilter membrane and photoelectrochemical sensors for Ru3+ were successfully developed. Moreover, the strategy was extended to the synthesis of crystalline zeolitic imidazolate framework-8 thin film, which exhibited high application potential.
196 citations
TL;DR: In this Review, the recent research progress on metastable MoS2 is summarized, especially with an emphasis on the diverse synthetic approaches and the newly uncovered physical properties.
Abstract: The 2H molybdenum disulfide (MoS2 ), as a stable hexagonal phase, has been one of the most studied transition metal dichalcogenides over the past decades. In the last five years, the metastable phases of MoS2 (1T, 1T', 1T'', and 1T''') have seen a revival of interests. Different from the edge-sharing [MoS6 ] trigonal prisms in the 2H MoS2 phase, these metastable phases are composed of the edge-sharing [MoS6 ] octahedra, in which the neighboring Mo-Mo distances differ. Due to the various crystal structures and different electronic configurations of the building [MoS6 ] motifs, these metastable polytypes are endowed with intriguing physical properties and potential applications in diverse fields. In this Review, the recent research progress on metastable MoS2 is summarized, especially with an emphasis on the diverse synthetic approaches and the newly uncovered physical properties. The phase structures and electronic band structures are also outlined. In the end, a perspective of the future investigation on metastable MoS2 is discussed.
107 citations
TL;DR: Some of the most recent advances in the construction of cyclic compounds from the annulation of Morita-Baylis-Hillman (MBH) adducts are summarized, which have demonstrated their importance by possessing diverse functional groups.
Abstract: In this review, we summarize some of the most recent advances in the construction of cyclic compounds from the annulation of Morita-Baylis-Hillman (MBH) adducts, which have demonstrated their importance by possessing diverse functional groups. Significant examples including [3 + 2], [3 + 3], [3 + 4] and other cyclizations described herein with MBH adducts were proven to be efficient approaches for the preparation of diverse cyclic structure motifs. However, most of the reported strategies are based on the use of non-chiral catalysts/ligands, whilst stereoselective reactions remain largely unexplored. This area is still in its infancy and future research on MBH adducts will definitely benefit the organic chemistry community, especially for the synthesis of drug candidates and other molecules that might draw attention to materials sciences.
78 citations
TL;DR: An efficient NIR-triggered nano-photosensitizer with promising antifungal and antibacterial efficacy for clinical antimicrobial therapy is revealed.
Abstract: An alarming worldwide increase in microbial resistance to traditional drugs and classical pharmacophores has spurred the search for new antimicrobial compounds. Antimicrobial photodynamic therapy (aPDT) has recently emerged as an effective modality for the selective destruction of bacteria and other pathogenic microorganisms. However, some of the factors, including the aggregation of the hydrophobic photosensitizer (PS) in aqueous media and the inefficient biodistribution of PS limit its expansion to clinical conditions. In addition, the photoactivation under visible-light irradiation limits the therapeutic effect of aPDT for deep-tissue infection. To overcome these limitations, a PS (β-carboxyphthalocyanine zinc, CPZ) delivery system with lanthanide-doped upconversion nanoparticles (UCNPs, LiYF4:Yb/Er) and polyvinylpyrrolidone (PVP) was prepared and its antimicrobial (antibacterial and antifungal) activities were investigated. Such a near-infrared (NIR) triggered UCNPs-CPZ-PVP system significantly reduced the aggregation of CPZ and presented a high anti-infectious activity against multi-drug resistant (MDR) bacteria (methicillin-resistant Staphylococcus aureus by 4.7 log10 and MDR Escherichia coli by 2.1 log10) post aPDT (at 50 μg mL-1 UCNPs-CPZ-PVP with 0.5 W cm-2 980 nm light). In particular, UCNPs-CPZ-PVP showed high antifungal efficacy against Candida albicans. In vivo aPDT experiments were further carried out using an MDR bacterial infection murine model in the presence of 5 mm thick tissue specimens, demonstrating the great potential of UCNPs-CPZ-PVP against infections in deep tissue. Altogether, we reveal an efficient NIR-triggered nano-photosensitizer with promising antifungal and antibacterial efficacy for clinical antimicrobial therapy.
71 citations
TL;DR: The physical properties measurements of electrical transport and magnetism indicate these TiO@TiO1+x nanocrystals are a type-Russian superconductor of a recorded Tconset = 11 K in the binary Ti-O system, which could open up possibilities in interface superconductivity of nanostructured composites with well-controlled interfaces.
Abstract: Nano TiO2 is investigated intensely due to extraordinary photoelectric performances in photocatalysis, new-type solar cells, etc., but only very few synthesis and physical properties have been reported on nanostructured TiO or other low valent titanium-containing oxides. Here, a core-shell nanoparticle made of TiO core covered with a ≈5 nm shell of amorphous TiO1+x is newly constructed via a controllable reduction method to synthesize nano TiO core and subsequent soft oxidation to form the shell (TiO1+x ). The physical properties measurements of electrical transport and magnetism indicate these TiO@TiO1+x nanocrystals are a type-ІІ superconductor of a recorded Tconset = 11 K in the binary Ti-O system. This unusual superconductivity could be attributed to the interfacial effect due to the nearly linear gradient of O/Ti ratio across the outer amorphous layer. This novel synthetic method and enhanced superconductivity could open up possibilities in interface superconductivity of nanostructured composites with well-controlled interfaces.
47 citations
TL;DR: A heterogeneous nucleation and growth method is reported to synthesize imine-linked covalent organic frameworks (COFs) and excellent crystallinity and a high surface area are obtained.
46 citations
TL;DR: Both in vitro and in vivo studies demonstrate that nuclear miR-122 participates in the regulation of HCC cell apoptosis through modulating themiR-21-targeted programmed cell death 4 (PDCD4) signal pathway.
Abstract: Hepatic miR-122 can serve as a pro-apoptotic factor to suppress tumorigenesis. The underlying mechanism, however, remains incompletely understood. Here we present the first evidence that miR-122 promotes hepatocellular carcinoma cell apoptosis through directly silencing the biogenesis of cell survival oncomiR miR-21 at posttranscriptional level. We find that miR-122 is strongly expressed in primary liver cell nucleus but its nuclear localization is markedly decreased in transformed cells particularly in chemoresistant tumor cells. MiRNA profiling and RT-qPCR confirm an inverse correlation between miR-122 and miR-21 in hepatocellular carcinoma tissues/cells, and increasing or decreasing nuclear level of miR-122 respectively reduces or increases miR-21 expression. Mechanistically, nuclear miR-122 suppresses miR-21 maturation via binding to a 19-nt UG-containing recognition element in the basal region of pri-miR-21 and preventing the Drosha-DGCR8 microprocessor's conversion of pri-miR-21 into pre-miR-21. Furthermore, both in vitro and in vivo studies demonstrate that nuclear miR-122 participates in the regulation of HCC cell apoptosis through modulating the miR-21-targeted programmed cell death 4 (PDCD4) signal pathway.
41 citations
TL;DR: These wide-spectrum absorption IBs bring about more solar energy utilization to enhance solar thermal collection and photocatalytic degradation of methyl orange.
Abstract: Intermediate band (IB) materials are of great significance due to their superior solar absorption properties. Here, two IBs peaking at 0.88 and 1.33 eV are reported to be present in the forbidden gap of semiconducting SnS2 ( Eg = 2.21 eV) by doping titanium up to 6 atom % into the Sn site via a solid-state reaction at 923 K. The solid solution of Sn1- xTi xS2 is able to be formed, which is attributed to the isostructural structure of SnS2 and TiS2. These two IBs were detected in the UV-vis-NIR absorption spectra with the appearance of two additional absorption responses at the respective regions, which in good agreement with the conclusion of first-principles calculations. The valence band maximum (VBM) consists mostly of the S 3p state, and the conduction band minimum (CBM) is the hybrid state composing of Ti 3d (eg), S 3p, and Sn 5s, and the IBs are mainly the nondegenerate t2g states of Ti 3d orbitals. The electronic states of Ti 3d reveal a good ability to transfer electrons between metal and S atoms. These wide-spectrum absorption IBs bring about more solar energy utilization to enhance solar thermal collection and photocatalytic degradation of methyl orange.
39 citations
TL;DR: The results suggested that the leaves of C. fangchengensis, rich in flavan-3-ol oligomers and monomers as potent antioxidants, could be a valuable plant resource for the production of tea and natural beverages.
Abstract: Camellia fangchengensis Liang et Zhong, belonging to the genus Camellia sect. Thea (Theaceae), is an endemic tea species to the south and southwest areas of Guangxi province, People's Republic of China. Known as a wild tea plant, the leaves have been used for producing green tea or black tea by the local people of its growing area. HPLC and LC-MS analysis showed the leaves contain oligomeric catechins as major phenolic components. Further detailed phytochemical study led to the identification of five flavan-3-ol dimers (1-5) including two new ones, fangchengbisflavans A (1) and B (2) from the leaves of C. fangchengensis, together with six known monomers (6-11) and one glucoside (12), in addition to gallic acid (13). Their structures were determined by extensive spectroscopic analysis. Most of the isolates displayed significant antioxidant activities in 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS+) radical scavenging assays. The results suggested that the leaves of C. fangchengensis, rich in flavan-3-ol oligomers and monomers as potent antioxidants, could be a valuable plant resource for the production of tea and natural beverages.
37 citations
TL;DR: The results indicated that C. sinensis var.
Abstract: Camellia sinensis var. pubilimba, one variety of the genus Camellia sect. Thea (Theaceae), has been used for producing green tea mainly by the local people of its growing areas of Guangxi province, China. Forty compounds, including eight C-8 N-ethyl-2-pyrrolidinone-substituted flavan-3-ols (1-8) and their substituted unit N-ethyl-5-hydroxy-2-pyrrolidinone (9), four flavan-3-ol monomers (10-13) and one dimer (14), nine flavonoids (15-23), three hydrolyzable tannins (24-26), two lignans (27-28), 11 simple phenolics (29-39), and caffeine (40), were first isolated and identified from the leaves. Their structures were determined by detailed spectroscopic analysis and comparison with the literature data and authentic samples. Both 1 and 4 were obtained as a mixture of the N-ethyl-2-pyrrolidinone C-5 enantiomers (1a and 1b and 4a and 4b), respectively, while the resolution of another three pairs of enantiomers (2 and 3, 5 and 6, and 7 and 8) was achieved. Among them, 1b is a new compound whose NMR data together with its enantiomer (1a) were reported for the first time, while 2 and 3 are two new natural products. Most of the isolates exhibited significant antioxidant activities, stronger than ascorbic acid and trolox, while parts of the isolates, particularly C-8 N-ethyl-2-pyrrolidinone-substituted flavan-3-ols, showed obvious inhibitory effects on acetylcholinesterase (AChE). The results indicated that C. sinensis var. pubilimba is a valuable plant resource for tea production.
TL;DR: It is shown that the GPP processes, as organic mass increases, can increase the proportions of semivolatile and intermediate-volatility organic compounds in the particle phase and result in the decrease of SOA RI real part, which indicates that the SOA optical properties are closely related to the total organic mass and molecular-level composition.
Abstract: The formation of secondary organic aerosols (SOAs) contains partitioning processes of the oxidation products between the gas and particle phases, which could change the particle-phase composition when particles grow. However, the effects of these processes on the optical properties of SOA remain poorly understood. In this study, we performed smog chamber experiments to investigate the effects of gas-particle partitioning (GPP) on the refractive index (RI) and chemical composition of the m-xylene SOA. Here, we show that the GPP processes, as organic mass increases, can increase the proportions of semivolatile and intermediate-volatility organic compounds (SVOCs and IVOCs) in the particle phase and result in the decrease of SOA RI real part for 0.09 ± 0.02 (without seeds) and 0.15 ± 0.02 (with seeds). This indicates that the SOA optical properties are closely related to the total organic mass and molecular-level composition. In addition, the presence of inorganic seeds promotes the GPP to the particle phase...
TL;DR: The research progress on Panax spp.
Abstract: Panax, a genus of the Araliaceae family, is an important herbal group in traditional Chinese medicine (TCM) Nine species and three varieties are included in the genus of Panax, in which nearly all species have been used for medicinal purposes Among them, Panax notoginseng (Burk) F H Chen, Panax ginseng C A Meyer and Panax quinquefolius L are the most representative and valuable herbs world-wide, with a long history of cultivation As the main bioactive chemical constituents, saponins with different aglycones are the major components in various Panax spp, and their pharmacological activities are mainly reflected in the effects on blood system, cardio- and cerebro-vascular systems, nervous system, metabolism, and immune regulation Researchers of Kunming Institute of Botany (KIB), Chinese Academy of Sciences (CAS), have put many efforts into conducting the investigations on Panax species Herein, we reviewed the research progress on Panax spp in KIB, CAS, over the past few decades, from the aspects of history and origin, phytochemistry and pharmacological activities
TL;DR: Two new alkaloids, rigidiusculamide E and [-(α-oxyisohexanoyl-N-methyl-leucyl)2-] (2), together with two known ones, (−)-oxysporidinone (3) and (−)-4,6′-anhydrooxysportidin one (4) were isolated from the mycelia culture of Fusarium tricinctum SYPF 7082, an endophy
Abstract: Panax notoginseng (Araliaceae) is a famous traditional Chinese medicine mainly cultivated in Yunnan and Guangxi provinces of China. Two new alkaloids, rigidiusculamide E (1) and [-(α-oxyisohexanoyl-N-methyl-leucyl)2-] (2), together with two known ones, (−)-oxysporidinone (3) and (−)-4,6′-anhydrooxysporidinone (4) were isolated from the mycelia culture of Fusarium tricinctum SYPF 7082, an endophytic fungus obtained from the healthy root of P. notoginseng. Their structures were determined on the basis of extensive spectroscopic analyses. Compounds 1–4 were tested for their inhibitory effects against NO production on Murine macrophage cell line, and the new compound 2 showed significant inhibitory activity on NO production with the IC50 value of 18.10 ± 0.16 μM.
TL;DR: This method provides a sustainable and efficient access to synthesize various indole-fused cyclohexanyl acetic acids under mild conditions.
Abstract: We disclose herein a Ru(II)-catalyzed decarboxylative and oxidative coupling of N-substituted indolyl carboxylic acids with broad substrate scope in an aqueous solution. This method provides a sustainable and efficient access to synthesize various indole-fused cyclohexanyl acetic acids under mild conditions.
TL;DR: Four new cleistanthane diterpenoids, phyllaciduloids A-D (1-4), were isolated from the roots and stems of Phyllanthus acidus (L.) Skeels (Phyllanthaceae) and their structures were elucidated on the basis of extensive spectroscopic analysis.
TL;DR: This study points to a new research direction of reducing light illumination time by increasing potency of PS by studying the effect of light fluence of the two light sources on the PACT potency of ZnPc(Lys)5.
Abstract: Photodynamic antimicrobial chemotherapy (PACT) is considered a promising alternative to conventional antibiotic approach. We have previously developed a novel PS containing five lysine amino acids, pentalysine-β-carbonylphthalocyanine Zinc (ZnPc(Lys)5), which in the presence of light, is highly toxic against a range of bacterial strains, including hospital isolated, drug resistant Acinetobacter baumannii. Here, we study the effect of light fluence of the two light sources on the PACT potency of ZnPc(Lys)5. We observed that an exposure of E.coli to a red LED light for only 2 seconds (light fluence of 0.15 J/cm2) in the presence of ZnPc(Lys)5 significantly eradicated 80% of the E.coli. We further demonstrated that a light fluence of 4.5 J/cm2 from a household light source induced a noticeable photodynamic effect in vitro and in vivo animal model. This study points to a new research direction of reducing light illumination time by increasing potency of PS.
TL;DR: An ammonium iodide/hydrogen peroxide-mediated intramolecular oxidative amination of 3-aminoalkyl-2-oxindoles was achieved, affording the corresponding 3,2′-pyrrolidinyl spirooxindole and their 6- or 7-membered analogous in moderate to high yields.
Abstract: An ammonium iodide/hydrogen peroxide-mediated intramolecular oxidative amination of 3-aminoalkyl-2-oxindoles was achieved, affording the corresponding 3,2′-pyrrolidinyl spirooxindoles and their 6- or 7-membered analogous in moderate to high yields. This metal-free procedure features very mild reaction conditions, non-toxicity and easily handled hydrogen peroxide as a clean oxidant.
TL;DR: This unprecedented three-component iodoalkylation reaction is enabled by using (iodoethynyl)trimethylsilane as a radical initiator and iodide source and the 1,2-difunctionalization affords alkenyl iodides, which are versatile building blocks for the construction of tri-substituted alkene derivatives.
Abstract: We report the first catalyst-free and trans-selective iodoalkylation reaction of alkynes with a series of α-carbonyl compounds. This unprecedented three-component iodoalkylation reaction is enabled by using (iodoethynyl)trimethylsilane as a radical initiator and iodide source. The 1,2-difunctionalization affords alkenyl iodides, which are versatile building blocks for the construction of tri-substituted alkene derivatives.
21 Mar 2018-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the orientation dependence of creep properties of a Co-base single crystal superalloy at 982°C/248MPa was investigated, and the results showed the deformation of these specimens was all controlled by a 3 ǫ -slip and stacking faults.
Abstract: The orientation dependence of creep properties of a Co-base single crystal superalloy at 982 °C/248 MPa was investigated. The orientations of specimens tested were near [001, 011] and [111]. The results showed the deformation of these specimens was all controlled by a/3 slip and stacking faults. The specimens with orientation near [001] exhibited the best creep resistance. There were a few stacking faults with two orientations in the specimens with [001] orientation. Specimens with orientations near [111] and [011] showed shorter creep lives, and stacking faults with single orientation were observed.
TL;DR: Further phytochemical investigation of the steaming treated roots of Panax notoginseng (Araliaceae) led to the identification of two new dammarane-type triterpenoid saponins, notoginenoside SP20 and SP21, which showed no in vitro cytotoxicity against five human cancer cell lines.
TL;DR: In situ STM results reveal that herringbone-like and rhombus structures could transform into lamellar structures when the electrode potential is tuned negatively, and provide important insights into the understanding and precise control of molecular self-assembly on solid surfaces.
Abstract: We report the potential and concentration controlled assembly of an alkyl-substituted benzo[1,2-b:4,5-b′]dithiophene (DDBDT) on an Au(111) electrode by in situ electrochemical scanning tunneling microscopy (ECSTM). It is found that a lamellar structure is formed at low concentrations, while herringbone-like and rhombus structures are obtained at high concentrations. In situ STM results reveal that herringbone-like and rhombus structures could transform into lamellar structures when the electrode potential is tuned negatively. A phase diagram is obtained to illustrate the relationship and effects of concentration and substrate potential on the interfacial structures of DDBDT. Both the substrate potential and the solute concentration can modulate the self-assembly structure through changing the molecular surface density. The results provide important insights into the understanding and precise control of molecular self-assembly on solid surfaces through a combination of different approaches.
TL;DR: In this article, the crystalline structures transition of TiO2, Na8Ti5O14, Na2TiO3 and Na2 Ti3O7 during electrochemical deoxidation in CaCl2 NaCl melt were investigated via cyclic voltammetry (CV), constant voltage electrolysis, theoretical analysis and calculation.
21 Feb 2018-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, a probable method is proposed to eliminate the pedestal-like sideband by simply inserting a magnetic chicane before the self-seeding FEL undulator.
Abstract: Soft x-ray self-seeding has been proved to be a feasible method to improve the longitudinal coherence of high gain free-electron laser. However, a pedestal-like sideband in the spectrum has been observed in the experiment, which generally limits the purity of the radiation pulse and the user’s application. The previous theoretical study indicates that the pedestal-like sideband is mainly induced by microbunching instability generated from LINAC. In this paper, three dimensional simulations have been performed to confirm the analytical results and show the formation process of the spectral sideband. A probable method is proposed to eliminate the pedestal-like sideband by simply inserting a magnetic chicane before the self-seeding FEL undulator. Theoretical and numerical simulations have been performed and the results show that the proposed method can efficiently eliminate the microbunching-instability-induced sideband in a soft x-ray self-seeding FEL.
TL;DR: A pyrene-cored molecular quadripod 1,3,6,8-tetra(di( p-pyrid-4-ylphenyl)amino)pyrene (TAPyr) is presented as a noncovalent interfacial coupling reagent for the immobilization of coordination assemblies.
Abstract: A pyrene-cored molecular quadripod 1,3,6,8-tetra(di(p-pyrid-4-ylphenyl)amino)pyrene (TAPyr) is presented as a noncovalent interfacial coupling reagent for the immobilization of coordination assemblies. This bench-stable molecule is readily available and has a quadripod shape with four pyridine legs and four pyridine handles on the top exterior. By a simple and short dipping procedure under ambient conditions, TAPyr is firmly immobilized on electrode surfaces in an upright fashion as probed by electrochemical, absorption spectral, atomic force microscopy, and scanning tunneling microscopy analysis. Using Pd(PhCN)2Cl2 as a metallolinker, 4-ferrocenylpyridine, a pyridine-terminated monoruthenium complex 1, and a diruthenium complex 2 with two pyridine ends have been grafted onto the ITO/TAPyr surface. The obtained thin films exhibit good electrochemical stability that is comparable or superior to those prepared by the state-of-the-art Si–O–Sn covalent functionalization. Appealing electrochromism is demonstra...
TL;DR: A conceptual approach is shown to realize the scanning tunneling microscopy based induced-assembly of fullerene (C60) molecules on top of a buffer organic adlayer at room temperature in a solution environment.
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16 Aug 2018
TL;DR: Moreovoer et al. as mentioned in this paper reported a 2M WS2 new compound constructed from 1T' WS2 monolayers, whose superconducting transition temperature Tc of 8.8 K is the highest among all the intrinsic TMDs.
Abstract: Recently intriguing physics of superconductivity, type-II Weyl semimetal or quantum spin Hall states was discovered in metastable 1T'-type VIB-group transition metal dichalcogenides (TMDs). Even the topological superconductivity can be induced if the superconductivity and nontrivial topology coexist in this type of materials. Here, we report 2M WS2 new compound constructed from 1T' WS2 monolayers, whose superconducting transition temperature Tc of 8.8 K is the highest among all the intrinsic TMDs. The coexistence of the electron and hole pockets was observed from first-principles calculations and Shubnikov-de Haas (SdH) oscillation. Moreovoer, the topological surface states with a single Dirac cone appear on the (100) surface. Our finding reveal a strong evidence of the topological superconductivity in the 1T' MX2 system.