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As a non-renewable resource, oil faces increasing demand, and the remaining oil recovery rates in existing oil fields still require improvement. The primary objective of this study is to investigate the impact of pore structure parameters on the distribution and recovery of residual oil after polymer flooding by constructing a digital pore network model. Using this model, the study visualizes the post-flooding state of the model with 3DMAX-9.0 software and employs a range of simulation methods, including a detailed analysis of the pore size, coordination number, pore–throat ratio, and wettability, to quantitatively assess how these parameters affect the residual oil distribution and recovery. The research shows that the change in the distribution of pore sizes leads to a decrease in cluster-shaped residual oil and an increase in columnar residual oil. An increase in the coordination number increases the core permeability and reduces the residual oil; for example, when the coordination number increases from 4.3 to 6, the polymer flooding recovery rate increases from 24.57% to 30.44%. An increase in the pore–throat ratio reduces the permeability and causes more residual oil to remain in the throat; for example, when the pore–throat ratio increases from 3.2 to 6.3, the total recovery rate decreases from 74.34% to 63.72%. When the wettability changes from oil-wet to water-wet, the type of residual oil gradually changes from the difficult-to-drive-out columnar and film-shaped to the more easily recoverable cluster-shaped; for example, when the proportion of water-wet throats increases from 0.1:0.9 to 0.6:0.4, the water flooding recovery rate increases from 35.63% to 51.35%. Both qualitative and quantitative results suggest that the digital pore network model developed in this study effectively predicts the residual oil distribution under different pore structures and provides a crucial basis for optimizing residual oil recovery strategies.

The detailed characterization of the pore structure in sandstone is pivotal for the assessment of reservoir properties and the efficiency of oil and gas exploration. Traditional fully supervised learning algorithms are limited in performance enhancement and require a substantial amount of accurately annotated data, which can be challenging to obtain. To address this, we introduce a semi-supervised framework with a U-Net backbone network. Our dataset was curated from 295 two-dimensional CT grayscale images, selected at intervals from nine 4 mm sandstone core samples. To augment the dataset, we employed StyleGAN2-ADA to generate a large number of images with a style akin to real sandstone images. This approach allowed us to generate pseudo-labels through semi-supervised learning, with only a small subset of the data being annotated. The accuracy of these pseudo-labels was validated using ensemble learning methods. The experimental results demonstrated a pixel accuracy of 0.9993, with a pore volume discrepancy of just 0.0035 compared to the actual annotated data. Furthermore, by reconstructing the three-dimensional pore structure of the sandstone, we have shown that the synthetic three-dimensional pores can effectively approximate the throat length distribution of the real sandstone pores and exhibit high precision in simulating throat shapes.

After polymer flooding, the heterogeneity between different layers intensifies, forming intricate seepage channels and fluid diversions, which results in decreased circulation efficiency and lower recovery rates, leaving a significant amount of residual oil trapped within the reservoir. Understanding the characteristics of residual oil occurrence is crucial for enhancing oil recovery post-polymer flooding. This study focused on sandstone reservoirs with varying permeability in the Saertu block of the Daqing oilfield. Using cryosectioning and laser scanning confocal microscopy, the occurrence characteristics of the residual oil in these sandstone reservoirs post-polymer flooding were investigated. Additionally, micro-CT and scanning electron microscopy were employed to analyze the impact of the pore structure on the distribution characteristics of the residual oil. The results indicate that laser scanning confocal images reveal that post-polymer flooding, the residual oil in high- and low-permeability sandstone reservoirs predominantly exists in a bound state (average > 47%), mostly as particle-adsorbed oil. In contrast, the residual oil in medium-permeability reservoirs is primarily in a free state (average > 49%), mostly as intergranular-adsorbed oil. In high-permeability sandstone reservoirs, heavy oil components are mainly in a particle-adsorbed form; in medium-permeability sandstone reservoirs, residual oil predominantly consists of heavy components, with most light components occurring in a clustered form; in low-permeability sandstone reservoirs, clustered residual oil exists in a balanced coexistence of light and heavy components, while the heavy components primarily exist in a particle-adsorbed form. Post-polymer flooding, the large pore–throat structure in high-permeability sandstone reservoirs results in effective displacement and less free residual oil; medium-permeability sandstone reservoirs, with medium–large pores and throats, have preferential channels and fine particles blocking the throats, leading to some unswept pores and more free residual oil; low-permeability sandstone reservoirs, with small pores and throats, exhibit weak displacement forces and poor mobility, resulting in more bound residual oil. The distribution and content of clay particles and clay minerals, along with the complex microscopic pore structure, are the main factors causing the differences in the residual oil occurrence states in sandstones with varying permeability.

Combined therapy has attracted extensive attention as a potential solution to overcome tumor heterogeneity and drug resistance. However, developing simple and effective multifunctional therapeutic platforms remain to be further explored. Herein, we have constructed a hybrid nanoplatform composed of a hierarchically porous porphyrinic coordination network (HP-PCN) as the core and copper sulfide (CuS) nanoparticles (NPs) as the satellites to realize combined chemodynamic therapy (CDT)/photodynamic therapy (PDT)/photothermal therapy (PTT) of cancer. HP-PCN exhibits excellent photodynamic properties but its antitumor effect is limited by the insufficient penetration depth of laser and hypoxic tumor microenvironment (TME). To overcome the shortcomings of photodynamic monotherapy, we introduce negatively charged CuS NPs on the HP-PCN surface taking advantage of its porous structure and positive surface charge to fabricate core-satellite HP-PCN@CuS nanoplatform. CuS NPs have excellent photothermal performances and additional CDT function by reacting with hydrogen peroxide in the TME. The integration of HP-PCN and CuS NPs enables the hybrid nanosystem more potent antitumor efficiency. In vitro and in vivo experiments have shown that HP-PCN@CuS presents an combined CDT/PDT/PTT effect to significantly inhibit tumor growth with low systemic toxicity. This study provides a promising strategy to fabricate multifunctional therapeutic nanoplatforms for effective and combined antitumor applications.

Abstract The over‐exploitation of land resources poses a serious threat to biodiversity on a global scale. Changes in land‐use and human exploitation have had a major impact on wild populations and their habitat in China. We assessed how habitat quality has changed over time (1995–2020). Specifically, we analyzed how the habitat quality of crocodile lizard has changed over time based on multi‐temporal land‐use data (1995, 2000, 2010, 2015 and 2020) using a land‐use transfer matrix and habitat quality model. The results showed that the main landscape types in the study area were arable land (21.21% of the area) and woodland (69.59% of the area) during the period. Construction land (land used for development) had decreased by 991 km2, a decrease rate of 59.84% from 1995 to 2000, and increased to 2349 km2, an increase rate of 71.69% from 2000 to 2020. The proportion of grasslands and areas with water were negligible and overall, did not vary significantly in size over the study period. The main feature of land use change in the study area was the loss of grasslands and woodlands through development. The habitat quality model indicated that habitat quality was highest and degradation was lowest in Dayao mountain, Guxiu town, Qichong village and Beituo town. Habitat quality improved in Daguishan and Luokeng areas. Habitat quality was good in Daping mountain and Linzhouding, but they were highly fragmented with patches of low‐quality habitat of varying sizes. Habitats were severely degraded in the Dateng Gorge area. The rate of habitat degradation has slowed over time in the study area, but gradually increased in degradation intensity, and low‐quality habitats were widely distributed and overlapped with the crocodile lizards distribution area. We recommend that protected areas for the crocodile lizard be more closely monitored and managed to halt further decline in habitat quality.

Diamond-coated tools often fail due to coating graphitization and delamination caused by poor coating adhesion, large contact stress, and thermochemical reactions. To address these issues, this research utilized a combination of micro-nano double-layer diamond coating, WS2 coating, and micro-textures. The WS2 coating inhibits the graphitization of the diamond coating through a transfer film mechanism, while the micro-textures and nanocrystalline diamond coating store WS2, resulting in a prolonged lubrication life. Additionally, the influence of micro-texture on coating-substrate residual stress and coating-substrate mechanical interlocking was discussed, and it was proved that proper micro-textures effectively improve the coating adhesion. Under the same cutting flux conditions, taking coating peeling as the judging standard, the cutting distance of textured WS2/Micro-Nano diamond coating tool is more than three times that of ordinary, diamond-coated tools, which greatly improves the service life of the tool.

The crocodile lizard (Shinisaurus crocodilurus) is an endangered ancient reptile species. Captive breeding is an important conservation measure for the potential restoration and recovery of their wild populations. However, a skin ulcer disease caused by an unknown pathogen has become a serious threat to captive breeding individuals. In the current study, based on microbial isolation, we identified Pseudomonas aeruginosa as the dominant pathogen in skin ulcer disease. Chinese skinks (Plestiodon chinensis) were used to verify the pathogenicity of P. aeruginosa in skin ulcer disease in vivo. As expected, subcutaneous inoculation of P. aeruginosa induced skin disease in healthy skinks and P. aeruginosa was re-isolated from the induced skin ulcers. Therefore, P. aeruginosa, an opportunistic and ubiquitous pathogen that causes a wide range of infections, appears to be the main pathogen of the skin disease affecting crocodile lizards. In the aquaculture industry, probiotics are widely used in the prevention and control of animal diseases caused by such pathogens. Here, we administered probiotics to the breeding crocodile lizards for 6 months. The three experiment groups treated with different kinds of probiotics showed significance at controlling case incidence. Three of the four groups treated with probiotics showed significant disease prevention (Effective Microorganisms mixed probiotics P = 0.0374; Double-dose Effective Microorganisms, P = 0.0299; Bacillus subtilis, P = 0.0140, T-test), and CFUs in the water of the breeding enclosures were also inhibited after probiotics usage (P < 0.001, T-test). Our study demonstrated the role of Pseudomonas aeruginosa in development of skin ulcer disease of crocodile lizards in a local zoo and offered the probiotic-based method for control measurements, which would be of benefit for the conservation of endangered reptiles.

To explore the effect of ginsenoside Rd on the biological characteristics of lung adenocarcinoma H1299 cell line. Firstly, 10 µmol/l ginsenoside Rd, 20 µmol/l ginsenoside Rd, 40 µmol/l ginsenoside Rd, 80 µmol/l ginsenoside Rd, 160 µmol/l ginsenoside Rd were applied to treat H1299 cell line. 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide assay was used to measure the inhibitory rate of glutathione reductase on cell viability, and the half-maximal inhibitory concentration value was calculated as 48.17 µmol/l. After treating H1299 cell line with 48.17 µmol/l ginsenoside Rd for 3 d, effects of ginsenoside Rd on proliferation ability, migration ability, and apoptosis were respectively detected using Ki67 immunofluorescence, Transwell culture system, and terminal deoxynucleotidyl transferase dUTP nick end labeling assay kit. Ginsenoside Rd had inhibitory effects on the viability of H1299 cells, and the inhibition is concentration-dependent. The half-maximal inhibitory concentration value is 131.92 µmol/l; compared to the control group, treatment of H1299 cells with 130 µmol/l ginsenoside Rd induced a significant decrease in Ki67-positive cells number and migratory cells. However, there was hardly any observed apoptosis in both groups. Ginsenoside Rd can suppress activity, proliferation ability, and migration capability of H1299 cell line, which indicates a noticeable suppression of malignancy in H1299 cells. Ginsenoside Rd may have potential therapeutic effects in the tr eatment of lung adenocarcinoma. [ABSTRACT FROM AUTHOR]

In this study, we propose a highly efficient robot platform for pollutant adsorption. This robot system consists of a flapping-wing micro aircraft (FWMA) for long-distance transportation and delivery and cost-effective multifunctional Janus microrobots for pollutant purification. The flapping-wing micro air vehicle can hover for 11.3 km with a flapping frequency of approximately 15 Hz, fly forward up to 31.6 km/h, and drop microrobots to a targeted destination. The Janus microrobot, which is composed of a silica microsphere, nickel layer, and hydrophobic layer, is used to absorb the oil and process organic pollutants. These Janus microrobots can be propelled fast up to 9.6 body lengths per second, and on-demand speed regulation and remote navigation are manageable. These Janus microrobots can continuously carry oil droplets in aqueous environments under the control of a uniform rotating magnetic field. Because of the fluid dynamics induced by the Janus microrobots, a highly efficient removal of Rhodamine B is accomplished. This smart robot system may open a door for pollutant purification.

In this letter, we investigated the spin polarized photocurrents excited by mid-infrared radiation and near-infrared radiation, respectively, in InAs/GaSb type II superlattices with different kinds of interfaces. By periodically varying the polarization state of the radiation, we analyzed Rashba-type and Dresselhaus-type spin polarized photocurrents, which present different features depending on the interface types and excitation conditions. Under mid-infrared excitation, the ratio of Rashbatype and Dresselhaus-type spin polarized photocurrents of the superlattice with InSb-like interface is obviously larger than that of the superlattice with GaAs-like interface, the ratio of the superlattice with alternate interface is in the middle. Whereas under near-infrared excitation, the ratios of the three superlattices are nearly the same. Further researches reveal the synactic effects of interface dependent strain and asymmetric interface potential on the spin splitting. Besides, the polarized Raman spectroscopies of these structures were also analyzed. [ABSTRACT FROM AUTHOR]

The spin polarization under low electric fields ( =300 V/cm) at low temperatures has been studied in undoped InGaAs/AlGaAs multiple quantum well. The spin polarization was created by optical spin orientation using circularly polarized light and the inverse spin-Hall effect was employed to measure the spin polarization current. We observed an obvious spin depolarization especially at lower temperatures (80-120K). We ascribed the spin depolarization of the photoinduced electrons to the heating effect from the low electric fields (the low field regime 50-300V/cm). This spin depolarization due to the heating effect is sensitive to temperature and electric field, suggesting a wide range of potential applications and devices. [ABSTRACT FROM AUTHOR]

Dirac-like surface states on surfaces of topological insulators have a chiral spin structure with spin locked to momentum, which is interesting in physics and may also have important applications in spintronics. In this work, by measuring the tunable helicity-dependent photocurrent (HDP), we present an identification of the HDP from the Dirac-like surface states at room temperature. It turns out that the total HDP has two components, one from the Dirac-like surface states, and the other from the surface accumulation layer. These two components have opposite directions. The clear gate tuning of the electron density as well as the HDP signal indicates that the surface band bending and resulted surface accumulation are successfully modulated by the applied ionic liquid gate, which provides a promising way to the study of the Dirac-like surface states and also potential applications in spintronic devices. [ABSTRACT FROM AUTHOR]

Rapid detection and accurate diagnosis for thrust drop fault are still open problems for launch vehicles. Existing studies have achieved fruitful results in fault detection and diagnosis (FDD) methods, leaving the complex disturbances not fully considered. The disturbances degrade FDD performance and are very hard to identify. In this paper, an FDD method based on multiple deep neural networks is proposed, which can deal with the complex disturbances. First, we split the FDD into two parts to reduce complexity. In detail, a fully connected neural network is selected to detect fault and diagnose fault degree, and a long short-term memory neural network is carefully tuned to diagnose fault mode. An analysis of the relationship between flight states and fault conditions is employed to design input of the fully connected neural network and the long short-term memory neural network. Then, a novel prediction and compensation method is proposed to deal with the unobservable and time-varying disturbances. Without extra information, data from the inertial measurement unit and navigation system are just enough to eliminate the disturbances, whereas existing methods may need more sensors. At last, illustrative simulations demonstrate the effectiveness and correctness of the proposed method. [ABSTRACT FROM AUTHOR]