Effects of Sulfate Ions on Crude Oil Adsorption/Desorption on Carbonate Rocks: Experimental and Molecular Simulations.

In the background of the strong oil wettability and low production by water flooding in carbonate reservoirs, low-salinity water containing sulfate ions can significantly change the surface wettability of carbonate rocks and thus increase the sweeping area; however, the absorption and desorption mechanisms of the oil film in the carbonate rock surface remain unclear. This paper analyzed the wettability alternation of carbonate rocks' surface in pure water and sodium sulfate solution. At the same time, MD (Materials Studio) software was used to simulate the formation process of the oil film and the effect of sulfate ions on the desorption of the oil film on the surface of carbonate rocks. The experimental results showed that sodium sulfate solution could accelerate the rate from oil-wet to water-wet and the final contact angle (49°) was smaller than that in pure water. The simulation results showed that dodecane molecules moved to the surface of calcite to form a double layer of the oil film and that the oil film near the calcite surface had a high-density stable structure under the van der Waals and electrostatic action. The hydrating sulfate ions above the oil film broke through the double oil film to form a water channel mainly under the action of electrostatic force and a hydrogen bond and then adsorbed on the calcite surface. A large number of water molecules moved down the water channel based on a strong hydrogen bonding force and crowded out the oil molecules on the surface of the calcite, resulting in the oil film detachment. This work aims to explain the interaction of oil molecules, water molecules, and SO42- ions at the molecular scale and guide the practical application of low-salinity water flooding in carbonate reservoirs.

Unsupervised Deraining: Where Asymmetric Contrastive Learning Meets Self-Similarity.

Most existing learning-based deraining methods are supervisedly trained on synthetic rainy-clean pairs. The domain gap between the synthetic and real rain makes them less generalized to complex real rainy scenes. Moreover, the existing methods mainly utilize the property of the image or rain layers independently, while few of them have considered their mutually exclusive relationship. To solve above dilemma, we explore the intrinsic intra-similarity within each layer and inter-exclusiveness between two layers and propose an unsupervised non-local contrastive learning (NLCL) deraining method. The non-local self-similarity image patches as the positives are tightly pulled together and rain patches as the negatives are remarkably pushed away, and vice versa. On one hand, the intrinsic self-similarity knowledge within positive/negative samples of each layer benefits us to discover more compact representation; on the other hand, the mutually exclusive property between the two layers enriches the discriminative decomposition. Thus, the internal self-similarity within each layer (similarity) and the external exclusive relationship of the two layers (dissimilarity) serving as a generic image prior jointly facilitate us to unsupervisedly differentiate the rain from clean image. We further discover that the intrinsic dimension of the non-local image patches is generally higher than that of the rain patches. This insight motivates us to design an asymmetric contrastive loss that precisely models the compactness discrepancy of the two layers, thereby improving the discriminative decomposition. In addition, recognizing the limited quality of existing real rain datasets, which are often small-scale or obtained from the internet, we collect a large-scale real dataset under various rainy weathers that contains high-resolution rainy images. Extensive experiments conducted on different real rainy datasets demonstrate that the proposed method obtains state-of-the-art performance in real deraining.

Direction and Residual Awareness Curriculum Learning Network for Rain Streaks Removal.

Single-image rain streaks' removal has attracted great attention in recent years. However, due to the highly visual similarity between the rain streaks and the line pattern image edges, the over-smoothing of image edges or residual rain streaks' phenomenon may unexpectedly occur in the deraining results. To overcome this problem, we propose a direction and residual awareness network within the curriculum learning paradigm for the rain streaks' removal. Specifically, we present a statistical analysis of the rain streaks on large-scale real rainy images and figure out that rain streaks in local patches possess principal directionality. This motivates us to design a direction-aware network for rain streaks' modeling, in which the principal directionality property endows us with the discriminative representation ability of better differing rain streaks from image edges. On the other hand, for image modeling, we are motivated by the iterative regularization in classical image processing and unfold it into a novel residual-aware block (RAB) to explicitly model the relationship between the image and the residual. The RAB adaptively learns balance parameters to selectively emphasize informative image features and better suppress the rain streaks. Finally, we formulate the rain streaks' removal problem into the curriculum learning paradigm which progressively learns the directionality of the rain streaks, rain streaks' appearance, and the image layer in a coarse-to-fine, easy-to-hard guidance manner. Solid experiments on extensive simulated and real benchmarks demonstrate the visual and quantitative improvement of the proposed method over the state-of-the-art methods.

Determining the effects of blended learning using the community of inquiry on nursing students' learning gains in sudden patient deterioration module.

AIMS: To determine the effectiveness of blended learning using the community of inquiry framework on nursing students' learning gains in a sudden patient deterioration module. DESIGN: A quasi-experimental trial. METHODS: 233 Chinese nursing students in their fourth semester of a sudden patient deterioration learning module were assigned to control (N = 113) and experimental group (N = 120). Students in experimental group engaged in community of inquiry-based blended learning in sudden patient deterioration module, including computer-aided self-instruction, team-based topic discussion and simulation training. Control group learned similar contents through face-to-face teaching comprising of a presentation with lecture, tutorial and simulation training. Student assessment of learning gains, knowledge and practical ability was quantified after the interventions. RESULTS: Compared with control group, students in experimental group had improved student assessment of learning gains (p = .001, Cohen d = 0.69) and practical ability (p < .001, Cohen d = 0.48). Although no significant difference in overall knowledge score, experimental group students did better performance in application and analysis (p = .001, Cohen d = 0.45).

Polymer LEDs with improved efficacy via periodic nanostructure-based aluminum.

Periodic aluminum-capped nanoslit arrays were produced on a polycarbonate plastic substrate by rapid hot embossing nanoimprint lithography and thermal evaporation, and they were used as a transparent window for blue-emitting polymer light-emitting diodes (PLEDs). The external quantum efficiency of blue-emitting PLEDs was enhanced by the surface plasmon polaritons of the periodic aluminum-capped nanoslit arrays. A maximum current efficiency of 4.84 cd/A was achieved for the proposed PLED, which was over 2.2 times that of the reference PLED (2.18 cd/A). These results demonstrate that periodic nanostructure can assist in the simple and low-cost fabrication of high-performance polymer optoelectronic devices.

Efficacy improvement in polymer LEDs via silver-nanoparticle doping in the emissive layer.

The coupling of surface plasmons and excitons in the emissive layer (EML) can improve the performance of polymer light-emitting diodes (PLEDs). Silver nanoparticles (Ag-NPs) with a decahedron structure are prepared by the chemical reduction and photochemical methods and doped directly into the EML after the phase-transfer process. The surface plasmon resonance effect of Ag-NPs, which makes full use of quenched excitons and increases the efficiency of excitons in the EML in a PLED, enhances the current efficacy by a factor of 75 relative to that of the undoped reference device (from 0.22 to 16.64 cd/A). These results demonstrate that Ag-NPs can assist in simple and low-cost fabrication of high-performance polymer optoelectronic devices.

Nanoscale electrical properties of ZnO nanorods grown by chemical bath deposition.

Well-aligned zinc oxide nanorod arrays (ZNAs) synthesized using chemical bath deposition were fabricated on a gallium-doped zinc oxide substrate, and the effects of varying the precursor concentrations on the growth and nanoscale electrical properties of the ZNAs were investigated. The as-synthesized ZNAs were characterized using field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), conducting atomic force microscopy (CAFM), and scanning surface potential microscopy (SSPM). The FESEM and AFM images show that the growth rate in terms of length and diameter is highly sensitive to the precursor concentration. CAFM and SSPM analyses indicate that when concentrations of both the zinc acetate and hexamethylenetetramine solutions were 30 mM, the coverage percentages of the recordable and conducting regions on the ZNA surface were 48.3% and 0.9%, which is suitable for application in resistive random access memory devices.

Enhanced luminescence efficiency of Ag nanoparticles dispersed on indium tin oxide for polymer light-emitting diodes.

This study presents a substantial enhancement in electroluminescence achieved by depositing Ag nanoparticles on an ITO-coated glass substrate (Ag/ITO) for approximately 10-s to form novel window materials for use in polymer light-emitting diodes (PLEDs). The PLEDs discussed herein are single-layer devices based on a poly[9,9-dioctylfluorene-co-benzothiadiazole] (F8BT) emissive layer. In addition to its low cost, this novel fabrication method can effectively increase the charge transport properties of the active layer to meet the high performance requirements of PLEDs. Due to the increased conductivity and work function of the Ag/ITO substrate, the electroluminescence intensity was increased by nearly 3.3-fold compared with that of the same PLED with a bare ITO substrate.

Influence of gallium-doped zinc-oxide thickness on polymer light-emitting diode luminescence efficiency.

Conducting atomic force microscopy and scanning surface potential microscopy were used to study the local electrical properties of gallium-doped zinc oxide (GZO) films prepared by pulsed laser deposition (PLD) on a polyimide (PI) substrate. For a PLD deposition process time of 8 min, the root-mean-square roughness, coverage percentage of the conducting regions, and mean work function on the GZO surface were 2.33 nm, 96.6%, and 4.82 eV, respectively. When the GZO/PI substrate was used for a polymer light-emitting diode (PLED), the electroluminescence intensity increased by nearly 20% compared to a standard PLED, which was based on a commercial-ITO/glass substrate.

[Research on the universal analytic potential function applied to diatomic molecules].

A new method on constructing analytical potential energy functions is presented, and from this a analytical potential energy function applied to both neutral diatomic molecules and charged diatomic molecular ions is obtained. In this paper, the potential energy function is examined by 21 examples of eight different basic kinds of diatomic molecules or ions--homonuclear ground-state for neutral diatomic molecule Na2-X1 sigma g+, homonuclear excitation-state for neutral diatomic molecule C2-A1 pi(u), homonuclear ground-state for charged diatomic molecular ion He2+ -X2 sigma u+, homonuclear excitation-state for charged diatomic molecular ion N2+ -B2 sigma(u), heteronuclear ground-state for neutral diatomic molecule NaLi-X1 sigma g+, heteronuclear excitation-state neutral diatomic molecule BH-B1 sigma+, heteronuclear ground-state for charged diatomic molecular ion (BC)- -X3 pi, and heteronuclear excitation-state for charged diatomic molecular ion (CS)+ -A2 pi etc. The theoretical values of the vibrational energy level of molecules calculated by the potential energy function are compared with RKR (Rydberg-Klein-Rees) or experimental data, and as a consequence, all the results are precisely consistent with RKR data.

Differences between nanoscale structural and electrical properties of AZO:N and AZO used in polymer light-emitting diodes.

Conducting atomic force microscopy and scanning surface potential microscopy were adopted to investigate the nanoscale surface electrical properties of N-doped aluminum zinc oxide (AZO:N) films that were prepared by pulsed laser deposition (PLD) at various substrate temperatures. Experimental results demonstrated that when the substrate temperature is 150 degrees C and the N(2)O background pressure is 150 mTorr, the N-dopant concentration on the surface is optimal. In addition, the root-mean-square roughness value of the film surface, the low contact current (<400 nA) conducting region as a percentage of the total area, and the mean work function value are 1.43 nm, 96.9%, and 4.88 eV, respectively, all of which are better than those of the optimal AZO film made by PLD. This result indicates that N-doped AZO films are better for use as window materials in polymer light-emitting diodes.

Nanoscale surface electrical properties of zinc oxide films investigated by conducting atomic force microscopy.

In this study, conducting atomic force microscopy was employed to investigate the nanoscale surface electrical properties of zinc oxide (ZnO) films prepared by pulsed laser deposition (PLD) at different substrate temperatures for use as anode materials in polymer light-emitting diodes. The results show that the surface conductivity distribution of ZnO is related to its surface structure. At substrate temperatures of 150-200 degrees C, the conducting regions may cover over 90% of the ZnO thin-film surface, thus providing the best local conductivity. Moreover, heating at substrate temperatures of above 250 degrees C can effectively make the conductivity on the ZnO surface uniform. In particular, at substrate temperatures of around 300 degrees C, the conducting regions where currents are between 1 and 2 muA may cover as much as 83% of the surface, and furthermore, the transmission ratio in the visible range is higher than 80%. This is a rather ideal production temperature for the PLD for ZnO films.