Institutional Repository of Dalian Institute of Chemical Physics, CAS
Not a member yet
45557 research outputs found
Sort by
Oxygen Evolution Reaction over the Au/YSZ Interface at High Temperature
No full textThe oxygen evolution reaction (OER) is a sluggish electrocatalytic reaction in solid oxide electrolysis cells (SOECs) at high temperatures (600-850 degrees C). Perovskite oxide has been widely investigated for catalyzing the OER; however, the formation of cation-enriched secondary phases at the oxide/oxide interface blocks the active sites and decreases OER performance. Herein, we show that the Au/yttria-stabilized zirconia (YSZ) interface possesses much higher OER activity than the lanthanum strontium manganite/YSZ anode. Electrochemical characterization and density functional theory calculations suggest that the Au/YSZ interface provides a favorable path for OER by triggering interfacial oxygen spillover from the YSZ to the Au surface. In situ X-ray photoelectron spectroscopy results confirm the existence of spillover oxygen on the Au surface. This study demonstrates that the Au/YSZ interface possesses excellent catalytic activity for OER at high temperatures in SOECs
Multiplexed profiling of single-cell extracellular vesicles secretion
No full textExtracellular vesicles (EVs) are important intercellular mediators regulating health and diseases. Conventional methods for EV surface marker profiling, which was based on population measurements, masked the cell-to-cell heterogeneity in the quantity and phenotypes of EV secretion. Herein, by using spatially patterned antibody barcodes, we realized multiplexed profiling of single-cell EV secretion from more than 1,000 single cells simultaneously. Applying this platform to profile human oral squamous cell carcinoma (OSCC) cell lines led to a deep understanding of previously undifferentiated single-cell heterogeneity underlying EV secretion. Notably, we observed that the decrement of certain EV phenotypes (e.g., (CD63+) V) was associated with the invasive feature of both OSCC cell lines and primary OSCC cells. We also realized multiplexed detection of EV secretion and cytokines secretion simultaneously from the same single cells to investigate the multidimensional spectrum of cellular communications, from which we resolved tiered functional subgroups with distinct secretion profiles by visualized clustering and principal component analysis. In particular, we found that different cell subgroups dominated EV secretion and cytokine secretion. The technology introduced here enables a comprehensive evaluation of EV secretion heterogeneity at single-cell level, which may become an indispensable tool to complement current single-cell analysis and EV research
Waveform control in high-order harmonic generation via chirp gating technology
No full textLaser waveform control in high-order harmonic generation (HHG) has been investigated and discussed by using the two-color chirp gating technology. It is found that the multiple-acceleration-recombination process in HHG can be found in a specific 'W' waveform structure. Moreover, by changing the chirp forms as well as laser parameters, the multiple-acceleration-recombination process in the 'W' waveform structure can be controlled, which leads to the remarkable improvements of harmonic cutoff and harmonic yield. Consequently, a water window spectral continuum with a bandwidth of 488 eV and with an intensity enhancement of 10 times can be obtained. Further, by the Fourier transformation of some selected harmonics on this spectral continuum, three single attosecond pulses (SAPs) with the pulse durations of 38 as can be produced. With the introduction of inhomogeneous effect of the laser field, the HHG spectra with a larger harmonic cutoff and a broader spectral continuum can be obtained. Consequently, by the Fourier transformation of some selected harmonics on the spectral continuum, a number of water window SAPs with the pulse durations of 36 as can be obtained
Rhodium(III)-Catalyzed Annulation of Acetophenone O-Acetyl Oximes with Allenoates through Arene C-H Activation: An Access to Isoquinolines
No full textRhodium(III)-catalyzed annulation of acetophenone O-acetyl oximes with allenoates was achieved, affording isoquinolines in good to excellent yields with high regioselectivities under redox-neutral conditions. Allenoates acted as the C2 synthons in the annulation reaction. The present synthetic methodology features good functional group tolerance and avoids metal salts as the external oxidants. The proposed mechanism suggests that the reaction proceeds through arene C-H activation, allene insertion, and C-N coupling
Quantification of bisphenol A and its selected analogs in serum using pre-column derivatization with high-performance liquid chromatography and tandem mass spectrometry
No full textDue to regulation of the use of bisphenol A, several analogs serving as bisphenol A replacements have drawn substantial attention for their adverse health effects. To investigate their occurrence in humans and identify possible pollution sources, it is necessary to develop a sensitive method for total bisphenols detection. Thus, a method based on enzymolysis and liquid-liquid extraction followed by molecularly imprinted polymer solid-phase extraction and pre-column derivatization with high-performance liquid chromatography and tandem mass spectrometry was proposed. The developed method exhibited superior selectivity and sensitivity. The matrix effect can be eliminated to a great extent. The method detection limits for eight bisphenols were 0.05 similar to 0.19 ng/mL. Satisfactory recoveries (71 similar to 119%) were obtained by spiking bovine serum at three levels (0.8, 8 and, 20 ng/mL). The method was successfully applied to determine total bisphenols in the serum samples of children. Bisphenol A, bisphenol F, bisphenol S, bisphenol B and bisphenol F were detected with concentrations from below the method detection limit to 1.65, 0.45, 0.79, 2.04 and 0.17 ng/mL, respectively. These results indicate that bisphenol A remains the major pollutant among the studied bisphenols in children, whereas threats from bisphenol A analogs should also be monitored
One step rapid dispersive liquid-liquid micro-extraction with in-situ derivatization for determination of aflatoxins in vegetable oils based on high performance liquid chromatography fluorescence detection
No full textA rapid dispersive liquid-liquid micro-extraction (DLLME) with in-situ derivatization method for extraction and purification of aflatoxins (AFs) in vegetable oils was developed and evaluated. Oil extract, dichloromethane and trifluoroacetic acid were mixed and injected into water to form a cloudy solution. AFs in the oil were extracted into the numerous liquid droplets (with diameters from a few microns to dozens of microns) of extractant, where derivatization was carried out in situ. The proposed sample preparation method was coupled with high performance liquid chromatography with fluorescence detection (HPLC-FLD) for determination of four AFs in vegetable oils. The method showed excellent linearity in three orders of magnitude, good relative recoveries, good repeatability and high sensitivity with limits of detection in range of 0.005-0.03 ng/mL. The accuracy of the method was also verified by certified reference sample. Finally, different kinds of vegetable oils from the local supermarket were analyzed
Membranes Fabricated by Solvent treatment for Flow Battery: Effects of initial structures and intrinsic properties
No full textSolvent treatment has been proved to be a very simple and effective method to prepare high-performance porous membranes for flow batteries. However, the initial morphology and the properties of membrane materials will exert pivotal effects on the resultant performance of porous membranes. In this paper, according to comparing the differences in the morphology and performance of untreated and treated porous poly(ether sulfone) (PES) membranes with different porous structures, the influence of the initial morphology of membranes was clarified in detail. Moreover, the differences in the morphology and performance of untreated and treated porous poly (vinylidene fluoride) (PVDF), polusulfone (PSF) and poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) membranes were also investigated. By comparing various properties of PES, PVDF, PSF and PVDF-HFP polymers, the importance and criteria for selecting proper membrane materials when using the solvent treatment method were clarified. Furthermore, the VFB assembled with the resultant membrane could achieve an energy efficiency of 82.93% at 80 mA cm(-2), which could be comparable to that of the commercial Nafion 115. Therefore, this article is beneficial for designing high-performance porous membranes for flow batteries
MiR-223-3p functions as a tumor suppressor in lung squamous cell carcinoma by miR-223-3p-mutant p53 regulatory feedback loop
No full textBackground: MicroRNAs have an important role in diverse biological processes including tumorigenesis. MiR-223 has been reported to be deregulated in several human cancer types. However, its biological role has not been functionally characterized in lung squamous cell carcinoma (LSCC). The following study investigates the role of miR-223-3p in LSCC growth and metastasis and its underlying mechanism.
Methods: MicroRNA profiling analyses were conducted to determine differential miRNAs expression levels in LSCC tumor tissues that successfully formed xenografts in immunocompromised mice (XG) and failed tumor tissues (no-XG). RT-PCR and in situ hybridization (ISH) was performed to evaluate the expression of miR-223-3p in 12 paired adjacent normal tissues and LSCC specimens. Cell proliferation and migration were assessed by CCK-8, colony formation and Transwell assay, respectively. The role of miR-223-3p in LSCC tumorigenesis was examined using xenograft nude models. Bioinformatics analysis, Dual-luciferase reporter assays, Chromatin immunoprecipitation (ChIP) assay and Western blot analysis were used to identify the direct target of miR-223-3p and its interactions.
Results: MiR-223-3p was downregulated in LSCC tissues that successfully formed xenografts (XG) compared with tumor tissues that failed (no-XG), which was also significantly reduced in LSCC tissues compared with the adjacent normal tissues. Gain- and loss-of function experiments showed that miR-223-3p inhibited proliferation and migration in vitro. More importantly, miR-223-3p overexpression greatly suppressed tumor growth in vivo. Mechanistically, we found that mutant p53 bound to the promoter region of miR-223 and reduced its transcription. Meanwhile, p53 is a direct target of miR-223-3p. Thus, miR-223-3p regulated mutant p53 expression in a feedback loop that inhibited cell proliferation and migration.
Conclusions: Our study identified miR-223-3p, as a tumor suppressor gene, markedly inhibited cell proliferation and migration via miR-223-3p-mutant p53 feedback loop, which suggested miR-223-3p might be a new therapeutic target in LSCC bearing p53 mutations
A theoretical study on the excited-state intramolecular proton transfer mechanism of 4-dimethylaminoflavonol chemosensor
No full textIn this work, density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods are used to explore the excited-state intramolecular proton transfer (ESIPT) mechanism of a novel system 4-dimethylaminoflavonol (DAF). By analyzing the molecular electrostatic potential (MEP) surface, we verify that the intramolecular hydrogen bond in DAF exists in both the S-0 and S-1 states. We calculate the absorption and emission spectra of DAF in two solvents, which reproduce the experimental results. By comparing the bond lengths, bond angles, and relative infrared (IR) vibrational spectra involved in the hydrogen bonding of DAF, we confirm the hydrogen-bond strengthening in the S-1 state. For further exploring the photoexcitation, we use frontier molecular orbitals to analyze the charge redistribution properties, which indicate that the charge transfer in the hydrogen-bond moiety may be facilitating the ESIPT process. The constructed potential energy curves in acetonitrile and methylcyclohexane solvents with shortened hydrogen bond distances demonstrate that proton transfer is more likely to occur in the S-1 state due to the lower potential barrier. Comparing the results in the two solvents, we find that aprotic polar and nonpolar solvents seem to play similar roles. This work not only clarifies the excited-state behaviors of the DAF system but also successfully explains its spectral characteristics
Uniform Pd0.33Ir0.67 nanoparticles supported on nitrogen-doped carbon with remarkable activity toward the alkaline hydrogen oxidation reaction
No full textHighly efficient non-Pt electrocatalysts for the alkaline hydrogen oxidation reaction (HOR) are required to enable complete replacement of Pt in hydroxide exchange membrane fuel cells (HEMFCs). Herein, we report a facile synthesis of a series of 2.4-2.9 nm Pd1-xIrx (x = 0.33, 0.50, 0.67, 0.75, 0.80, 0.91) alloy nanoparticles (NPs) evenly distributed on nitrogen-doped carbon (N-C) via simple chemical reduction of aqueous metallic complexes by sodium borohydride (NaBH4) in the absence of surfactants. The Ir component of alloy NPs and the nitrogen dopants of the carbon matrix contribute to the particle size control and uniform distribution. Remarkably, the resultant Pd0.33Ir0.67/N-C exhibits an exceptional alkaline HOR activity, measured as mass specific exchange current density (j(0,m)), that is 1.4 times that of commercial Pt/C. CO stripping shows that Pd0.33Ir0.67/N-C has an electrochemical active surface area (ECSA) of 106 m(2) g(metal)(-1) that is 1.2 times that of commercial Pt/C, partially explaining the increased activity. Furthermore, density functional theory (DFT) demonstrates an appropriate strength of hydrogen binding of Pd0.33Ir0.67, which is consistent with cyclic voltammetry (CV) measurements. In addition, DFT shows that Pd0.33Ir0.67 possesses the highest oxophilic property among all of the Pd1-xIrx electrocatalysts. We conclude that the high ECSA, appropriate strength of hydrogen binding, and the strong oxophilic property collectively account for the remarkable activity of Pd0.33Ir0.67/N-C. The latter two factors should be closely correlated with the electronic effect between Pd and Ir as evidenced by Xray photoelectron spectroscopy (XPS). A single cell fabricated with Pd0.33Ir0.67/N-C as the anode approaches a peak power density of 514 mW cm(-2) that is 1.3 times that of commercial Pt/C. This study demonstrates the substitution of commercial Pt/C with a non-Pt electrocatalyst at the anode of the single cell of HEMFCs with enhanced performance