Synthesis of a monolayer fullerene network.

Two-dimensional (2D) carbon materials, such as graphene, have attracted particular attention owing to the exceptional carrier transport characteristics that arise from the unique π-electron system in their conjugated carbon network structure1-4. To complement zero-bandgap graphene, material scientists have devoted considerable effort to identifying 2D carbon materials5-8. However, it is a challenge to prepare large-sized single-crystal 2D carbon materials with moderate bandgaps5,9. Here we prepare a single-crystal 2D carbon material, namely monolayer quasi-hexagonal-phase fullerene (C60), with a large size via an interlayer bonding cleavage strategy. In this monolayer polymeric C60, cluster cages of C60 are covalently bonded with each other in a plane, forming a regular topology that is distinct from that in conventional 2D materials. Monolayer polymeric C60 exhibits high crystallinity and good thermodynamic stability, and the electronic band structure measurement reveals a transport bandgap of about 1.6 electronvolts. Furthermore, an asymmetric lattice structure endows monolayer polymeric C60 with notable in-plane anisotropic properties, including anisotropic phonon modes and conductivity. This 2D carbon material with a moderate bandgap and unique topological structure offers an interesting platform for potential application in 2D electronic devices.

3-Hydroxybutyrate helps crayfish resistant to Vibrio parahaemolyticus infection in versatile ways.

The bacterial storage compound poly-ß-hydroxybutyrate (PHB) is a potential bio-control agent in aquaculture. It has been reported that PHB benefit to the survival and growth, and improve their immunity of aquatic animals. However, the cellular and molecular regulation mechanisms of PHB in immunity process remain unclear. This study investigated the immune mechanism of hemocytes regulated by Halomonas-PHB (PHB-HM) and PHB monomer 3-HB. Red claw crayfish Cherax quadricarinatus was used as the experimental animal in cytological study. Fluorescence microscopy and flow cytometry (FCM) analysis indicated that PHB-HM labeled with fluorescein isothiocyanate (FITC) could be engulfed by granulocytes (Gs) and semi-granulocytes (SGs) upon in vitro incubation. Transmission electron microscopy (TEM) further showed the ongoing degradation of PHB granules inside Gs and SGs after the injection of PHB-HM into crayfish sinus, but phagocytosis of PHB-HM by hyalinocyte (H) was not observed. Therefore, Gs and SGs are considered the main effector cells of cellular immunity induced by PHB-HM, and SGs likely played a particular important role in this process. To study the biosafety and molecular mechanism of PHB monomer 3-HB, hemocyte viability and expression of the related genes were determined after being exposed to 0-1 mg/mL of 3-HB, and Vibrio parahaemolyticus (VP) was used as the pathogenic bacterium. The results confirmed that 3-HB had no toxic effect on hemocytes by means of cell viability assay, and supplementation with 1 mg/mL of 3-HB suppressed the growth rate of VP in TSB medium. Moreover, injection of 3-HB into the blood sinus of crayfish remarkably improved the phagocytic rate of Gs and SGs on VP. Furthermore, transcriptome assay was designed to illuminate the molecular mechanism of 3-HB regulation using red swamp crayfish Procambarus clarkii as experimental animals. RNA-seq analysis and qRT-PCR verification revealed that the microtubule and cytoskeleton-related genes were high expressed 3 h after 3-HB injection, indicating both genes might involve in building up the innate immunity. In summary, bacterial storage PHB could be phagocytosed by main effector blood cells and likely to be degraded within the cells. 3-HB helped the crayfish resistant to pathogens through improving phagocytosis, suppressing the growth of pathogenic bacteria, and increasing the expression of microtubule-related genes. The findings in this work provide cytological and molecular evidence which will facilitate the application of PHB and 3-HB as immune-control agents in farming of aquatic animals.

Visualization of Crystallographic Orientation and Twist Angles in Two-Dimensional Crystals with an Optical Microscope.

Recently, twisted two-dimensional (2D) bilayers have attracted intense interest due to the emergence of exotic physics in moiré superlattices arising from strong interactions between electrons in the two misaligned lattices. Accurate determination and control of crystallographic orientation is vital to construct twisted 2D bilayers. Here, we demonstrate a very simple method to visualize crystallographic orientation in various 2D crystals by directly imaging n-tritriacontane crystallites epitaxially grown on 2D crystals using an ordinary optical microscope. The specific orientation of the molecular assembly allows the lattice orientation of the underlying 2D crystals to be determined with a high precision using an optical microscope. When tested on a 2D bilayer comprising staggered stacked MoS2 crystals, the twist angle can also be determined accurately. Our findings offer a nondestructive method for determining the lattice structure of 2D crystals and their bilayers and can also be a metrology tool for establishing large-area surface crystalline order.

Fluorometric and electrochemical dual-mode nanoprobe for tetracycline by using a nanocomposite prepared from carbon nitride quantum dots and silver nanoparticles.

A fluorometric and electrochemical dual-mode method is described for sensitive and specific detection of tetracycline (Tc). A novel nanoprobe was designed that is making use of a Tc-specific aptamer (apta), carbon nitride quantum dots (CNQDs) and silver nanoparticles (AgNPs). The aptamer was linked to the CNQDs which then were used as templates to synthesize the apta-CNQD@AgNP nanocomposites. The blue fluorescence of the nanocomposites (with excitation/emission maxima at 365/440 nm) is quenched. The addition of Tc leads to fluorescence recovery and a decrease in the electroconductivity of a gold electrode modified with apta-CNQD@AgNPs. The fluorometric method has a linear response in the 0.1 µM - 10 mM Tc concentration range and a 15 nM detection limit. The amperometric method (best performed at a working voltage of 0.21 V vs. Ag/AgCl) has a linear response in the 1 nM to 0.1 mM Tc concentration range and a 0.26 nM detection limit. Recoveries of Tc from spiked milk samples were comparable to data obtained by HPLC. Graphical abstractA fluorometric and electrochemical dual-mode nanoprobe (apta-CNQD@AgNPs) was prepared from aptamer (apta), carbon nitride quantum dots (CNQDs) and silver nanoparticles (AgNPs). The nanoprobe can be used for determination of tetracycline (Tc) based on fluorescence recovery of apta-CNQD@AgNPs and a decrease in the electroconductivity of a gold electrode modified with apta-CNQD@AgNPs.

Therapeutic effect and mechanism of Ento-PB on ulcerative colitis in BALB/c mice induced by sodium dextran sulfate.

The traditional Chinese medicine (TCM) formula Ento-PB containing Periplaneta americana (Linnaeus) (Blattidae) and Taraxacum mongolicum Hand.-Mazz. (Compositae) has great potential for treating inflammation. Thus, this study aimed to explore the pharmacodynamic effect of Ento-PB on DSS-induced ulcerative colitis in BALB/c mice, and its effects on immune function, JAK2/STAT3-related signaling pathways and intestinal flora in UC mice. It was identified that the extract Ento-PB mainly contained 20 compounds, accounting for 78.50 % of the total peak area. Compared with the model group, each dose group of Ento-PB could reduce the DAI score, colon index, CMDI score and colon HS score of mice to varying degrees (P < 0.05 or P < 0.01). Ento-PB can reduce the content of IL-1ß, TNF-α, IFN-γ in serum and IL-7 and IL-17 in colonic tissue, and increase IL-2, IL-10 in serum and EGF in colonic mucosa, TGF-ß1 expression level (P < 0.05 or P < 0.01). In conclusion, Ento-PB has a good therapeutic effect on DSS-induced UC mice. Its mechanism of action may be to up-regulate the levels of IL-2, IL-10, EGF, IL-22 and TGF-ß1, and down-regulate the levels of TNF-α,IFN-γ, IL-7 and IL-17 in UC mice. This provides sufficient experimental basis for the clinical treatment of UC with Ento-PB.

circPVT1 Inhibits the Proliferation and Aids in Prediction of the Prognosis of Bladder Cancer.

Background: Circular RNA PVT1 (circPVT1) is aberrantly expressed in several cancers, but its functional role and clinical relevance in bladder urothelial carcinoma (BLCA) remain unknown. This study aimed to identify the expression level of circPVT1 in BLCA and investigated its functional relevance with BLCA progression both in vitro and in vivo. Methods: GEPIA, UALCAN, and OncoLnc were referred to presented data. Quantitative real-time PCR (qPCR) was used for the measurement of transnational expression of genes in BLCA specimens and cell lines. Immunohistochemistry (IHC) and fluorescence in situ hybridization analysis (FISH) assays were performed to detect HER2 amplification, Pearson's correlation analysis to analyze the correlation between circPVT1 expression and clinical characteristics, Cox regression and K-M survival analyses to analyze prognostic factors. A nomogram was constructed for predicting prognosis. The proliferation of cells was measured by CCK-8 and colony formation assay, and the proliferation in vivo was evaluated using nude mouse models. qPCR was used to detect the expression of proliferation-related genes. Results: circPVT1 was but mRNA PVT1 was not significantly overexpressed in BLCA. A high circPVT1 expression was associated with a better survival and negative HER2, but not with age, gender, and T stage. circPVT1 was an independent prognostic factor for the overall survival of BLCA patients. Knocking down circPVT1 promoted BLCA proliferation in vitro and in vivo. Knocking down circPVT1 upregulated ERBB2, MKI67, and PCNA expression and downregulated TP53 expression, but exerted no influence on CCND1 and CCNB1 expression. Conclusion: circPVT1 is a tumor suppressor and novel prognostic biomarker for BLCA.

Self-condensation-assisted chemical vapour deposition growth of atomically two-dimensional MOF single-crystals.

Two-dimensional metal-organic frameworks (MOFs) have a wide variety of applications in molecular separation and other emerging technologies, including atomically thin electronics. However, due to the inherent fragility and strong interlayer interactions, high-quality MOF crystals of atomic thickness, especially isolated MOF crystal monolayers, have not been easy to prepare. Here, we report the self-condensation-assisted chemical vapour deposition growth of atomically thin MOF single-crystals, yielding monolayer single-crystals of poly[Fe(benzimidazole)2] up to 62 µm in grain sizes. By using transmission electron microscopy and high-resolution atomic force microscopy, high crystallinity and atomic-scale single-crystal structure are verified in the atomically MOF flakes. Moreover, integrating such MOFs with MoS2 to construct ultrathin van der Waals heterostructures is achieved by direct growth of atomically MOF single-crystals onto monolayer MoS2, and enables a highly selective ammonia sensing. These demonstrations signify the great potential of the method in facilitating the development of the fabrication and application of atomically thin MOF crystals.

Organic covalent modification to improve thermoelectric properties of TaS2.

Organic semiconductors are attracting considerable attention as a new thermoelectric material because of their molecular diversity, non-toxicity and easy processing. The side chains which are introduced into two-dimensional (2D) transition metal dichalcogenides (TMDs) by covalent modification lead to a significant decrease in their thermal conductivity. Here, we describe a simple approach to preparing the side chains covalent modification TaS2 (SCCM-TaS2) organic/inorganic hybrid structures, which is a homogeneous and non-destructive technique that does not depend on defects and boundaries. Electrical conductivity of 3,401 S cm-1 and a power factor of 0.34 mW m-1 K-2 are obtained for a hybrid material of SCCM-TaS2, with an in-plane thermal conductivity of 4.0 W m-1 K-1, which is 7 times smaller than the thermal conductivity of the pristine TaS2 crystal. The power factor and low thermal conductivity contribute to a thermoelectric figure of merit (ZT) of ~0.04 at 443 K.

[Fluorescence spectroscopy characterization of asphaltene liquefied from coal and study of its association structure].

Structure and association of asphaltenes from coal direct hydroliquefaction were studied by fluorescence spectrometry and UV-Vis absorption spectrometry in this paper. The results indicate that asphaltene is aromatic mixtures mainly containing naphthalene nucleus and shows strong fluorescent characteristic. The forming of exciplex between asphaltene and solvent results in the red shift of fluorescence peak and fluorescence quenching of asphaltene that increases with the polarity and electron acceptability. The self-aggregation of asphaltene is formed by non-covalent bond interaction, so that the asphaltene liquefied at higher temperture that shows high aromaticity has stronger association than that liquefied at lower temperature. Aggregation of asphaltene has been found to be a gradual process, in which there is no critical aggregation constant observed, and the inflection point of the plot of apparent fluorescence intensity as a function of asphaltene concentration varies with the excitation wavelength.

Evaluation of the Heshang Cave stalagmite calcium isotope composition as a paleohydrologic proxy by comparison with the instrumental precipitation record.

With their merits of precise dating and sensitivity to climate changes, laminated stalagmites are an important terrestrial archive for reconstructions of paleohydrological changes. In particular, the Ca isotope composition (δ44/42Ca) of the Heshang Cave stalagmite has been documented to record a precipitation decrease during the 8.2 ka event in central China. As an extension, this study directly compares near-annual resolution δ44/42Ca data with an instrumental precipitation record to evaluate the fidelity of δ44/42Ca as a paleohydrologic proxy on annual to decade timescales. Over the period 1881-2001 AD, the δ44/42Ca values correlate significantly with both precipitation from a nearby weather station and the dryness/wetness index in the middle Yangtze River, with a stronger correlation on decadal smoothed data. These results clearly show that the δ44/42Ca ratio from stalagmites is an effective proxy for paleohydrological changes on a decadal timescale. More study is encouraged to refine understanding of stalagmite Ca isotope ratios and hydrological conditions and their application in paleohydrologic reconstructions.

Rolling up transition metal dichalcogenide nanoscrolls via one drop of ethanol.

Two-dimensional transition metal dichalcogenides (TMDs) have attracted lots of interest because of their potential for electronic and optoelectronic applications. Atomically thin TMD flakes were believed capable to scroll into nanoscrolls (NSs) with distinct properties. However, limited by mechanical strength and chemical stability, production of high-quality TMD NSs remains challenging. Here, we scroll chemical vapor deposition-grown monolayer TMD flakes into high-quality NSs in situ in 5 s with a nearly 100% yield by only one droplet of ethanol solution. An obvious photoluminescence is demonstrated in NSs and the self-encapsulated structure makes NSs more insensitive to external factors in optical and electrical properties. Furthermore, based on the internal open topology, NSs hybridized with a variety of functional materials have been fabricated, which is expected to confer TMD NSs with additional properties and functions attractive for potential application.

Direct Conversion of CH3NH3PbI3 from Electrodeposited PbO for Highly Efficient Planar Perovskite Solar Cells.

Organic-inorganic hybrid perovskite materials have recently been identified as a promising light absorber for solar cells. In the efficient solar cells, the perovskite active layer has generally been fabricated by either vapor deposition or two-step sequential deposition process. Herein, electrochemically deposited PbO film is in situ converted into CH3NH3PbI3 through solid-state reaction with adjacent CH3NH3I layer, exhibiting a large-scale flat and uniform thin film with fully substrate coverage. The resultant planar heterojunction photovoltaic device yields a best power conversion efficiency of 14.59% and an average power conversion efficiency of 13.12 ± 1.08% under standard AM 1.5 conditions. This technique affords a facile and environment-friendly method for the fabrication of the perovskite based solar cells with high reproducibility, paving the way for the practical application.

Electrodeposition of PbO and its in situ conversion to CH3NH3PbI3 for mesoscopic perovskite solar cells.

The perovskite CH3NH3PbI3 was prepared on a mesoscopic TiO2 film, starting from electrodepositing PbO, to iodination to PbI2, and then interdiffusion reaction with CH3NH3I. The as-prepared film was used as a light absorber for the perovskite solar cells, exhibiting a high PCE of 12.5% under standard AM 1.5 conditions.