Showing papers by "China University of Petroleum published in 2014"
TL;DR: The fundamental engineering principles used to design RCA nanotechnologies are introduced, the recently developed RCA-based diagnostics and bioanalytical tools are discussed, and the use of RCA to construct multivalent molecular scaffolds and nanostructures for applications in biology, diagnostic and therapeutics is summarized.
Abstract: Rolling circle amplification (RCA) is an isothermal enzymatic process where a short DNA or RNA primer is amplified to form a long single stranded DNA or RNA using a circular DNA template and special DNA or RNA polymerases. The RCA product is a concatemer containing tens to hundreds of tandem repeats that are complementary to the circular template. The power, simplicity, and versatility of the DNA amplification technique have made it an attractive tool for biomedical research and nanobiotechnology. Traditionally, RCA has been used to develop sensitive diagnostic methods for a variety of targets including nucleic acids (DNA, RNA), small molecules, proteins, and cells. RCA has also attracted significant attention in the field of nanotechnology and nanobiotechnology. The RCA-produced long, single-stranded DNA with repeating units has been used as template for the periodic assembly of nanospecies. Moreover, since RCA products can be tailor-designed by manipulating the circular template, RCA has been employed to generate complex DNA nanostructures such as DNA origami, nanotubes, nanoribbons and DNA based metamaterials. These functional RCA based nanotechnologies have been utilized for biodetection, drug delivery, designing bioelectronic circuits and bioseparation. In this review, we introduce the fundamental engineering principles used to design RCA nanotechnologies, discuss recently developed RCA-based diagnostics and bioanalytical tools, and summarize the use of RCA to construct multivalent molecular scaffolds and nanostructures for applications in biology, diagnostics and therapeutics.
788 citations
TL;DR: In this article, the principles of electrical plasma with liquids for pollutant removal and the reactors of various electrical discharge types are outlined in this review, and detailed discussions are given of the effects of various factors on the performance of pulsed electrical plasma technology in water treatment processes.
723 citations
TL;DR: In this article, the preparation, characterization, and application of perovskite oxides in heterogeneous catalysis is discussed. But the authors focus on the preparation and characterization of materials with desired textural structure and physicochemical properties.
Abstract: Perovskite oxides with formula ABO3 or A2BO4 are a very important class of functional materials that exhibit a range of stoichiometries and crystal structures. Because of the structural features, they could accommodate around 90% of the metallic natural elements of the Periodic Table that stand solely or partially at the A and/or B positions without destroying the matrix structure, offering a way of correlating solid state chemistry to catalytic properties. Moreover, their high thermal and hydrothermal stability enable them suitable catalytic materials either for gas or solid reactions carried out at high temperatures, or liquid reactions carried out at low temperatures. In this review, we addressed the preparation, characterization, and application of perovskite oxides in heterogeneous catalysis. Preparation is an important issue in catalysis by which materials with desired textural structure and physicochemical property could be achieved; characterization is the way to explore and understand the textura...
657 citations
Proceedings Article•
01 Jan 2014TL;DR: The social presence factors are found to have positive impacts on trust in sellers, and a multi-dimensional model of social presence is proposed, which delineates a full picture of online buyer behaviors in social commerce.
540 citations
TL;DR: In this paper, the impact of fractal dimension on adsorption capacity has been discussed based on the physical description of the fractal surfaces, and the authors showed that fractal geometries with fractal dimensions ranging from 2.68 to 2.83 were obtained from the nitrogen adsorptions data using the Frenkel-Halsey-Hill method.
493 citations
TL;DR: This work systematically characterize chemical vapour deposition-grown Monolayer molybdenum disulfide by photoluminescence spectroscopy and mapping and demonstrates non-uniform strain in single-crystalline monolayer MoS2 and strain-induced bandgap engineering.
Abstract: Monolayer molybdenum disulfide (MoS2) has attracted tremendous attention due to its promising applications in high-performance field-effect transistors, phototransistors, spintronic devices and nonlinear optics. The enhanced photoluminescence effect in monolayer MoS2 was discovered and, as a strong tool, was employed for strain and defect analysis in MoS2. Recently, large-size monolayer MoS2 has been produced by chemical vapour deposition, but has not yet been fully explored. Here we systematically characterize chemical vapour deposition-grown MoS2 by photoluminescence spectroscopy and mapping and demonstrate non-uniform strain in single-crystalline monolayer MoS2 and strain-induced bandgap engineering. We also evaluate the effective strain transferred from polymer substrates to MoS2 by three-dimensional finite element analysis. Furthermore, our work demonstrates that photoluminescence mapping can be used as a non-contact approach for quick identification of grain boundaries in MoS2.
462 citations
TL;DR: In this article, a series of composites of graphitic carbon nitride and in situ nitrogen-doped titanium dioxide (g-C3N4-N-TiO2) were prepared by a simple pyrolysis process of urea and Ti(OH)4.
Abstract: A series of composites of graphitic carbon nitride and in situ nitrogen-doped titanium dioxide (g-C3N4-N-TiO2) were prepared by a simple pyrolysis process of urea and Ti(OH)4. The obtained products were characterized by means of X-ray diffraction, FT-IR transmission spectroscopy, electron microscopy, UV–vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, etc. Compared with g-C3N4 and commercial P25, the as-prepared photocatalysts exhibit enhanced photocatalytic performance for photoreduction of CO2 in the presence of water vapor at room temperature. It was found that the mass ratios of urea to Ti(OH)4 in precursors play a role in formation of the composites, and the high ratios of urea to Ti(OH)4 result in the composites of g-C3N4 and N-doped TiO2, while low ratios only result in N-doped TiO2. An interesting selectivity of photocatalytic products displayed that N-doped TiO2 samples were related to CH4 and CO generation, while g-C3N4 and N-TiO2 composites were related to CO generation, and the product selectivity may originate from the formed g-C3N4. The highest amount of CO (14.73 μmol) was obtained on the optimized photocatalyst under 12 h light irradiation, which is four times of that over commercial P25. Based on these results, a possible mechanism for the enhanced photocatalytic performance was proposed.
423 citations
TL;DR: In this article, a chemically reduced graphene oxide (RGO)/poly(diallylimethyammonium chloride) (PDDA) nanocomposite film sensor with high-performance humidity properties was reported.
Abstract: Chemically reduced graphene oxide (RGO)/poly(diallylimethyammonium chloride) (PDDA) nanocomposite film sensor with high-performance humidity properties was reported in this paper. The film sensor was fabricated on flexible polyimide substrate with interdigital microelectrodes structure. By the layer-by-layer nano self-assembly approach, graphene oxide and PDDA were exploited to form hierarchical nanostructure, and then was partially reduced via solution-based chemically reduction for obtaining both conductivity and chemically active defect sites. The effect of hydrobromic acid treatment on the conductivity properties of PDDA/GO film was examined, further verifying the advantage of hydrobromic acid reduction. The humidity sensing properties of the presented nanocomposite film sensor, such as repeatability, hysteresis, stability, response–recovery characteristics, were investigated by exposing to the wide relative humidity range of 11–97% at room temperature. As a result, the sensor exhibited not only excellent sensing behavior to humidity, but also fast response–recovery time and good repeatability, highlighting the unique advantages of layer-by-layer nano self-assembly for film sensors fabrication. As last, the possible humidity sensing mechanism of the proposed sensor was discussed in detail.
419 citations
TL;DR: In this paper, the effects of multiple factors on propagating rules of fractures of horizontal well in shale with hydraulic fracturing were studied, and the fracture morphology of post-fracturing rock cores was observed for the first time by high-energy CT scanning using the large-scale non-destructive testing system based on linear accelerator.
370 citations
TL;DR: In this article, a new visible-light-induced Co 3 O 4 -g-C 3 N 4 heterojunction photocatalysts were synthesized via a facile mixing-and-heating method.
Abstract: Novel visible-light-induced Co 3 O 4 -g-C 3 N 4 heterojunction photocatalysts were synthesized via a facile mixing-and-heating method. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), ultraviolet–visible diffuse reflection spectroscopy (DRS), electron spin resonance (ESR) and photoluminescence spectroscopy (PL). The heterojunction photocatalysts exhibit a significantly enhanced photocatalytic activity in degrading methyl orange (MO). The optimal Co 3 O 4 content with the highest photocatalytic activity was determined to be 0.2 wt%. The synergetic effect between Co 3 O 4 and g-C 3 N 4 plays an important role in promoting photo-generated carrier separation. The ESR and PL results reveals that the enhanced photocatalytic activity of Co 3 O 4 -g-C 3 N 4 was mainly due to the superior amount and longer lifetime of oxidative radicals ( O 2 − ), as well as the efficient separation of charge carriers. Possible mechanism is proposed for the high photocatalytic activity of heterojunction structures, to guide the design of photocatalysts.
336 citations
TL;DR: In this paper, partially hydrophobic modified SiO2 nanoparticles with an anionic surfactant, sodium dodecyl sulfate (SDS), were used together to increase foam stability.
Abstract: Nitrogen foam flooding is a promising technique for enhanced oil recovery, but instability of the foam limits its application. In this article, partially hydrophobic modified SiO2 nanoparticles with an anionic surfactant, sodium dodecyl sulfate (SDS), were used together to increase foam stability. Micromodel flooding and sandpack flooding were adopted to assess the stability and effect on enhanced oil recovery of the SiO2 stabilized foam (SiO2/SDS foam). The experimental data showed that the foam stability was decreased with an increase in temperature, while the foam volume was increased first and then decreased. SiO2/SDS foam showed better temperature tolerance than the SDS foam (foam stabilized by SDS) due to the adsorption of nanoparticles on the surface of the bubble. Almost all of the bubbles maintained spherical or ellipsoidal shape with prolonged time due to the enhanced surface dilational viscoelasticity, which was different from that of SDS foam. According to the micromodel flooding results, SiO2...
TL;DR: In this paper, a simple procedure for fabricating flexible, free-standing, and magnetic film of GO/CNT-Fe3O4 composites by using a one-pot co-precipitation in situ growth route was reported.
Abstract: We report a simple procedure for fabricating flexible, free-standing, and magnetic film of GO/CNT–Fe3O4 composites by using a one-pot co-precipitation in situ growth route. Characterizations including X-ray diffraction, Raman spectroscopy, superconducting quantum interference device magnetometry, scanning electron microscopy and transmission electron microscopy have been carried out to investigate the morphology, crystalline structure and magnetic properties of the composites. The layered structure of the as-prepared composites is porous and superparamagnetic. The GO/CNT–Fe3O4 composites exhibit excellent microwave absorbing properties in the range of 2–18 GHz and are expected to be promising candidates as microwave absorbing materials.
TL;DR: The results show that the fault diagnosis model using evidences from only sensor data is accurate for single fault, while it is not accurate enough for multiple-simultaneous faults, and the multi-source information fusion based fault diagnosed model using Bayesian network can increase the fault diagnostic accuracy greatly.
TL;DR: In vitro toxicity data suggest that the DOX-GQD-FA nanoassembly can target HeLa cells differentially and efficiently while exhibiting significantly reduced cytotoxicity to non-target cells.
TL;DR: The distributed activation energy model (DAEM) has been usually used to describe the pyrolysis kinetics of lignocellulosic biomass and its application to the application of the DAEM to the pyrotechnics of LBSs is discussed in this article.
Abstract: Research interest in the conversion of lignocellulosic biomass into energy and fuels through the pyrolysis process has increased significantly in the last decade as the necessity for a renewable source of carbon has become more evident. For optimal design of pyrolysis reactors, an understanding of the pyrolysis kinetics of lignocellulosic biomass is of fundamental importance. The distributed activation energy model (DAEM) has been usually used to describe the pyrolysis kinetics of lignocellulosic biomass. In this review, we start with the derivation of the DAEM. After an overview of the activation energy distribution and frequency factor in the DAEM, we focus on the numerical calculation and parameter estimation methods of the DAEM. Finally, this review summarizes recent results published in the literature for the application of the DAEM to the pyrolysis kinetics of lignocellulosic biomass.
TL;DR: The Changbaishan volcanic complex in China cannot be easily explained as the consequence of a mantle plume as discussed by the authors, but it has been shown that buoyant mantle material may have been entrained and dragged downwards by the subducting Pacific Plate, but is now escaping upwards through a gap in the plate and producing the intraplate volcanism.
Abstract: The Changbaishan volcanic complex in China cannot be easily explained as the consequence of a mantle plume. Seismic images from the region identify buoyant mantle material that may have been entrained and dragged downwards by the subducting Pacific Plate, but is now escaping upwards through a gap in the plate and producing the intraplate volcanism.
TL;DR: In this article, a super-hydrophobic surface with self-cleaning was successfully deposited on AZ91D magnesium alloy by the nickel plating process, and the surface morphologies, chemical composition, wettability and corrosion resistance were characterized by means of SEM, FT-IR, water contact angle and electrochemical impedance spectroscopy (EIS) measurements.
TL;DR: In this paper, a multilayered self-assembled graphene oxide/polyelectrolyte (GO/PDDA) nanocomposite was fabricated on a polyimide substrate using layer-by-layer self-assembly technique.
Abstract: A ultrahigh performance humidity sensor based on graphene oxide (GO)/poly(diallyldimethylammonium chloride) (PDDA) nanocomposite film was reported in this paper. The multilayered film of GO/PDDA was fabricated on a polyimide substrate using layer-by-layer self-assembly technique. The structures of the self-assembled films were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The humidity sensing behaviors of the film sensor were investigated at room temperature over a wide range of 11–97% relative humidity. Unprecedented response of up to 265,640% was demonstrated for the presented sensor when exposed to varying relative humidity levels, which is better than that of the best conventional humidity sensor. Furthermore, the presented sensor exhibited ultrafast response and recovery times capable of monitoring human breath. Moreover, the possible humidity sensing mechanism of the proposed sensor was discussed by using complex impedance spectra and bode diagrams. This measurement results observed highlight the layer-by-layer self-assembled graphene oxide/polyelectrolyte film is a candidate material for constructing humidity sensors.
TL;DR: There is a threshold of the stochastic model which determines the outcome of the disease in case the white noises are small, and sufficient conditions for extinction and persistence in mean are obtained.
TL;DR: In this paper, the authors developed a novel denoising method termed fx empirical-mode decomposition (EMD) predictive filtering, which solved the problem that makes fx predictive filtering ineffective with complex seismic data.
Abstract: Random noise attenuation always played an important role in seismic data processing. One of the most widely used methods for suppressing random noise was f‐x predictive filtering. When the subsurface structure becomes complex, this method suffered from higher prediction errors owing to the large number of different dip components that need to be predicted. We developed a novel denoising method termed f‐x empirical-mode decomposition (EMD) predictive filtering. This new scheme solved the problem that makes f‐x EMD ineffective with complex seismic data. Also, by making the prediction more precise, the new scheme removed the limitation of conventional f‐x predictive filtering when dealing with multidip seismic profiles. In this new method, we first applied EMD to each frequency slice in the f‐x domain and obtained several intrinsic mode functions (IMFs). Then, an autoregressive model was applied to the sum of the first few IMFs, which contained the high-dip-angle components, to predict the useful ste...
TL;DR: The results show that the PNG is a promising candidate for anode materials in high-rate LIBs, showing much enhanced electrode performance as compared to the undoped few-layered porous graphene.
Abstract: Few-layered graphene networks composed of phosphorus and nitrogen dual-doped porous graphene (PNG) are synthesized via a MgO-templated chemical vapor deposition (CVD) using (NH4)3PO4 as N and P source. P and N atoms have been substitutionally doped in graphene networks since the doping takes place at the same time with the graphene growth in the CVD process. Raman spectra show that the amount of defects or disorders increases after P and N atoms are incorporated into graphene frameworks. The doping levels of P and N measured by X-ray photoelectron spectroscopy are 0.6 and 2.6 at %, respectively. As anodes for Li ion batteries (LIBs), the PNG electrode exhibits high reversible capacity (2250 mA h g–1 at the current density of 50 mA g–1), excellent rate capability (750 mA h g–1 at 1000 mA g–1), and satisfactory cycling stability (no capacity decay after 1500 cycles), showing much enhanced electrode performance as compared to the undoped few-layered porous graphene. Our results show that the PNG is a promisi...
TL;DR: It is illustrated in this paper that some classical types of Lyapunov functions can be seen as special cases of the proposed CPLF, and it is proved that the conservativeness of the obtained criteria can be further reduced as the degree of the LyAPunov function increases.
TL;DR: A series of Fe x -Cu 4 /ZSM-5 catalysts with fixed Cu content and variable Fe loading amounts were synthesized by an improved incipient-wetness-impregnation method, and their catalytic performances were tested for selective catalytic reduction (SCR) of NO with ammonia as reductant as discussed by the authors.
Abstract: A series of Fe x –Cu 4 /ZSM-5 catalysts with fixed Cu content and variable Fe loading amounts were synthesized by an improved incipient-wetness-impregnation method, and their catalytic performances were tested for selective catalytic reduction (SCR) of NO with ammonia as reductant. The catalysts were characterized by means of XRD, BET, SEM, TEM, FT-IR, UV–vis DRS, UV-Raman, NH 3 -TPD, Py-IR, H 2 -TPR and XPS. The results indicated that the high activities of Fe x –Cu 4 /ZSM-5 could be attributed to the formation of Fe–Cu nanocomposites with high dispersion. The interaction between the iron and copper species in the Fe–Cu nanocomposites leads to the change of electronic properties, the stronger redox ability and more acid sites over catalyst surface for Fe x –Cu 4 /ZSM-5 comparing with Cu 4 /ZSM-5. Thus, the addition of iron to Cu 4 /ZSM-5 catalyst improved its catalytic performance, and Fe 4 –Cu 4 /ZSM-5 catalyst exhibited the high NO conversion (>90%) among the wide temperature range (200–475 °C).
TL;DR: In this article, a new strategy for preparation of water-soluble photoluminescent carbon quantum dots (CQDs) from petroleum coke was reported, and the results showed that the quantum yield of CQDs increases greatly from 8.7 to 15.8%, and the fluorescent lifetime increases from 3.86 to 6.11 ns after the hydrothermal treatment in ammonia.
TL;DR: Owing to the synergy of the HIFs and the electronic effect of the Pt-Ni alloy, the as-prepared CNC and HOH Pt- Ni alloy NCs exhibited excellent catalytic properties for the electrooxidation of methanol and formic acid, as well as for the oxygen reduction reaction (ORR).
Abstract: The shape-controlled synthesis of multicomponent metal nanocrystals (NCs) bounded by high-index facets (HIFs) is of significant importance in the design and synthesis of high-activity catalysts. We report herein the preparation of Pt-Ni alloy NCs by tuning their shape from concave-nanocubic (CNC) to nanocubic and hexoctahedral (HOH). Owing to the synergy of the HIFs and the electronic effect of the Pt-Ni alloy, the as-prepared CNC and HOH Pt-Ni alloy NCs exhibited excellent catalytic properties for the electrooxidation of methanol and formic acid, as well as for the oxygen reduction reaction (ORR).
TL;DR: In this paper, the threshold behavior of a susceptible-infected-recovered (SIR) epidemic model with stochastic perturbation was investigated, and it was shown that the threshold determines the extinction and persistence of the epidemic.
TL;DR: In this paper, a multiview Hessian discriminative sparse coding (mHDSC) is proposed to integrate Hessian regularization with sparse coding for image annotation.
TL;DR: Li et al. as mentioned in this paper proposed an extended data envelopment analysis model, named GB-US-SBM model, which combines global benchmark technology, undesirable output, super efficiency and slacks-based measure.
TL;DR: A phylogenetic tree is constructed and the relationship between taxonomy and acetoin producing ability is revealed for the first time, which will serve as a useful guide for the screening of competitive acetoin producers.
TL;DR: In this paper, geochronological, geochemical and geological data from thirty intrusions are summarised in the Fujian coastal area, and the data provide distinct magmatic, geochemic and tectonic patterns in the area.