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Coiled tubing endures significant pressure and fluid impact throughout the oil and gas production and transportation processes. The abrasive action of sand-carrying liquids against the pipe wall leads to gradual thinning, compromising its ability to bear pressure and tension, ultimately resulting in fractures and leaks. To address this concern, this study conducts liquid–solid two-phase steady-state erosion experiments on coiled tubing flushed with sand-carrying liquids. The experiments choose CT110, TS110 and QT1100 tubing samples, explore various particle properties, fluid factors, and pipeline conditions to investigate the thinning rate caused by erosion. The CT110 coiled tubing exhibits a higher erosion rate when subjected to sand-laden fluid erosion in the experiment. This characteristic proves beneficial in numerical simulations, as it allows for a more pronounced demonstration of the effectiveness of erosion prediction models under equivalent conditions. A predictive model for coiled tubing erosion and thinning has been established by incorporating erosion theory and the discrete phase model. The discrete phase model adeptly comprehends and describes the experimental phenomena associated with sand-carrying fluid erosion. By providing comprehensive experimental data and theoretical analysis, this article facilitates the prediction of the uniform thinning rate of the oil pipe wall and enables the estimation of its service life. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to evaluate the clinical feasibility of early 30-minute dynamic 2-deoxy-2-[18F]fluoro-D-glucose (18F-FDG) positron emission tomography (PET) scanning protocol for patients with lung lesions in comparison to the standard 65-minute dynamic FDG-PET scanning as a reference. Methods: Dynamic 18F-FDG PET images of 146 patients with 181 lung lesions (including 146 lesions confirmed by histology) were analyzed in this prospective study. Dynamic images were reconstructed into 28 frames with a specific temporal division protocol for the scan data acquired 65 min post-injection. Ki images and quantitative parameters Ki based on two different acquisition durations [the first 30 min (Ki-30 min) and 65 min (Ki-65 min)] were obtained by applying the irreversible two-tissue compartment model using in-house Matlab software. The two acquisition durations were compared for Ki image quality (including visual score analysis and number of lesions detected) and Ki value (including accuracy of Ki, the value of differential diagnosis of lung lesions and prediction of PD-L1 status) by Wilcoxon's rank sum test, Spearman's rank correlation analysis, receiver operating characteristic (ROC) curve, and the DeLong test. The significant testing level (alpha) was set to 0.05. Results: The quality of the Ki-30 min images was not significantly different from the Ki-65 min images based on visual score analysis (P > 0.05). In terms of Ki value, among 181 lesions, Ki-65 min was statistically higher than Ki-30 min (0.027 ± 0.017 ml/g/min vs. 0.026 ± 0.018 ml/g/min, P < 0.05), while a very high correlation was obtained between Ki-65 min and Ki-30 min (r = 0.977, P < 0.05). In the differential diagnosis of lung lesions, ROC analysis was performed on 146 histologically confirmed lesions, the area under the curve (AUC) of Ki-65 min, Ki-30 min, and SUVmax was 0.816, 0.816, and 0.709, respectively. According to the Delong test, no significant differences in the diagnostic accuracies were found between Ki-65 min and Ki-30 min (P > 0.05), while the diagnostic accuracies of Ki-65 min and Ki-30 min were both significantly higher than that of SUVmax (P < 0.05). In 73 (NSCLC) lesions with definite PD-L1 expression results, the Ki-65 min, Ki-30 min, and SUVmax in PD-L1 positivity were significantly higher than that in PD-L1 negativity (P < 0.05). And no significant differences in predicting PD-L1 positivity were found among Ki-65 min, Ki-30 min, and SUVmax (AUC = 0.704, 0.695, and 0.737, respectively, P > 0.05), according to the results of ROC analysis and Delong test. Conclusions: This study indicates that an early 30-minute dynamic FDG-PET acquisition appears to be sufficient to provide quantitative images with good-quality and accurate Ki values for the assessment of lung lesions and prediction of PD-L1 expression. Protocols with a shortened early 30-minute acquisition time may be considered for patients who have difficulty with prolonged acquisitions to improve the efficiency of clinical acquisitions. [ABSTRACT FROM AUTHOR]

To address the problem of high adsorption of coalbed methane (CBM), a hydraulic cavitation tool for CBM production enhancement was designed based on the mechanism of cavitation wave promoting CBM production enhancement. To achieve the best cavitation performance and generate high-intensity cavitation waves to promote CBM desorption, the influence of inlet flow rate and upper and lower nozzle diameter ratio on cavitation performance was investigated by CFD technique and cavitation jet experiment. The simulation and experimental results show that as the inlet flow rate increases, the cavitation effect in the oscillation chamber increases, and the throttling pressure difference increases, so the throttling pressure difference is used to characterize the cavitation performance of the cavitation tool. The cavitation performance of the cavitation tool is analyzed when the upper and lower nozzle diameter ratio is from 1.5 to 3 and the inlet flow rate is from 2 to 10 m3/h. When the upper and lower nozzle diameter ratio is 2, the inlet flow rate is 6 m3/h, the throttling pressure difference increases by 73.2%, the value of vapor volume fraction increases by 77.7%, the cavitation effect no longer increases, achieving optimal cavitation performance. As a result, the high-intensity cavitation waves generated by the cavitation tool can continuously propagate in the formation, play a continuous oscillating effect on the coal seam, and can significantly increase the gas production of coalbed methane. The research results can provide new ideas for the development of CBM production enhancement tools. [ABSTRACT FROM AUTHOR]

Background: Dynamic positron emission tomography (PET) images are useful in clinical practice because they can be used to calculate the metabolic parameters (Ki) of tissues using graphical methods (such as Patlak plots). Ki is more stable than the standard uptake value and has a good reference value for clinical diagnosis. However, the long scanning time required for obtaining dynamic PET images, usually an hour, makes this method less useful in some ways. There is a tradeoff between the scan durations and the signal-to-noise ratios (SNRs) of Ki images. The purpose of our study is to obtain approximately the same image as that produced by scanning for one hour in just half an hour, improving the SNRs of images obtained by scanning for 30 min and reducing the necessary 1-h scanning time for acquiring dynamic PET images. Methods: In this paper, we use U-Net as a feature extractor to obtain feature vectors with a priori knowledge about the image structure of interest and then utilize a parameter generator to obtain five parameters for a two-tissue, three-compartment model and generate a time activity curve (TAC), which will become close to the original 1-h TAC through training. The above-generated dynamic PET image finally obtains the Ki parameter image. Results: A quantitative analysis showed that the network-generated Ki parameter maps improved the structural similarity index measure and peak SNR by averages of 2.27% and 7.04%, respectively, and decreased the root mean square error (RMSE) by 16.3% compared to those generated with a scan time of 30 min. Conclusions: The proposed method is feasible, and satisfactory PET quantification accuracy can be achieved using the proposed deep learning method. Further clinical validation is needed before implementing this approach in routine clinical applications. [ABSTRACT FROM AUTHOR]

Downhole throttling technology is of great significance to the stable production of natural gas. Downhole throttle is widely used by major oil and gas fields. In view of the frequent failure of downhole throttle, downhole throttling mechanism and relevant literature on downhole throttle failure were studied and analyzed. It is concluded that: (1) structural failure of downhole throttle mainly occurs in the rubber cylinder, slip and throttle nozzle; (2) under the condition of satisfying the strength of slip and rubber cylinder, it is necessary to further study and analyze the problem that jamming of slip and inability of rubber cylinder to rebound effectively by using new soluble materials; (3) for the traditional throttle nozzle with fixed diameter, it is necessary to salvage the throttle when replacing it, which is time-consuming, tedious, costly and easy to lead to throttle failure. Under the premise of not changing normal operating environment, it is the future research direction to adjust the diameter of throttle nozzle effectively, conveniently and intelligently according to real-time downhole temperature and pressure conditions; (4) the large amount of sand produced from the wellbore is the main cause of failure of downhole throttle salvaging operation. The problems that throttle salvaging failure and erosion of throttle anti-sand screen tube are caused by wellbore sand production have been well researched in the innovation of throttle salvaging tools. It is necessary to further study the anti-sand screen tube, multistage anti-sand and anti-sand structure. It points out the direction of further research on downhole throttle. [ABSTRACT FROM AUTHOR]

Because microbial corrosion is one of the major threats to the service life of buried pipeline steel, it is very important to predict the service life of X90 pipeline steel in a microbial corrosion environment. In this study, the hoop stress of pipeline steel is determined according to the calculation of the corrosion rate. The calculation model of stress intensity factor is obtained by comparing and selecting the M-parameter model method and Ballellle method, considering normal distribution and 3σ. The calculation method of ductile crack arrest reliability is obtained according to the criterion, and the variation of stress intensity factor and reliability of X90 pipeline steel with the increase in service life under different microbial corrosion rates is obtained. The ductile crack failure analysis using American Standard dot 49 CFR Part 192 is compared with the prediction results of strength check failure analysis using national standards GB 50251, GBT 34275, and GB150. The prediction results show that the ductile crack failure risk probability of X90 Pipeline Steel is higher than that of strength failure. For the ductile crack failure mode, the prediction of the failure life of pipeline steel with 8 steel pipes is slightly stricter than that with 5 steel pipes. [ABSTRACT FROM AUTHOR]

With the development of gas well exploitation, the calculation of wellbore with single-phase state affected by single factor cannot meet the actual needs of engineering. We need to consider the simulation calculation of complex wellbore environment under the coupling of multiphase and multiple factors, so as to better serve the petroleum industry. In view of the problem that the commonly used temperature and pressure model can only be used for single-phase state under complex well conditions, and the error is large. Combined with the wellbore heat transfer mechanism and the calculation method of pipe flow pressure drop gradient, this study analyzes the shortcomings of Ramey model and Hassan & Kabir model through transient analysis. Based on the equations of mass conservation, momentum conservation and energy conservation, and considering the interaction between fluid physical parameters and temperature and pressure, the wellbore pressure coupling model of water-bearing gas well is established, and the Newton Raphael iterative method is used for MATLAB programming. On this basis, the relationship between tubing diameter, gas production, gas–water ratio, and wellbore temperature field and pressure field in high water-bearing gas wells is discussed. The results show that the wellbore temperature pressure coupling model of high water-bearing gas well considering the coupling of gas–liquid two-phase flow wellbore temperature pressure field has higher accuracy than Ramey model and Hassan & Kabir model, and the minimum coefficients of variation of each model are 0.022, 0.037 and 0.042, respectively. Therefore, the model in this study is highly consistent with the field measured data. Therefore, the findings of this study are helpful to better calculate the wellbore temperature and pressure parameters under complex well conditions. [ABSTRACT FROM AUTHOR]

In view of the failure causes of downhole choke fishing in tight gas wells, taking the choke fishing failure in Daning–Jixian block as representative, the failure causes are summarized through the actual fishing data and phenomena on site. This study analyzes from 11 aspects: (1) the influence of fishing time on throttle fishing; (2) the influence of the running depth of the choke on the fishing success rate of the choke; (3) the influence of gas well effusion on the success rate of choke fishing; (4) the influence of sand production on choke fishing; (5) the influence of restrictor structure on fishing success rate; (6) life analysis of restrictor; (7) type selection of throttle; (8) throttle structure design; (9) choke fishing; (10) choke sand blockage; (11) impact of switching well. This paper analyzes the methods to improve the fishing success rate of a choke and puts forward a reasonable solution to the fishing failure of choke, to ensure the safety of tight gas well construction. [ABSTRACT FROM AUTHOR]

The capacity of soil to store carbon (C) and emit carbon dioxide (CO2) into the atmosphere primarily depends on soil management practices. It is essential to understand the impact of management strategies on the soil organic carbon (SOC) content and labile organic carbon (LOC) fraction. The impacts of 24‑year-long organic and inorganic nitrogen (N) treatments on SOC, KMnO4-oxidizable organic carbon and its fractions (highly labile organic carbon (HLOC), moderately labile organic carbon (MLOC), low labile organic carbon (LLOC) and nonlabile organic carbon (NLOC)), and a carbon management index (CMI) were investigated under a continuous maize cultivation system in a long-term experiment in Guizhou, Southwest China. Six fertilizer treatments were included: no fertilizer input (CK), chemical fertilizer alone (NPK), 25% N through farmyard manure (FYM) plus 75% N through chemical fertilizer (1/4N-M+3/4N-CF), 50% N through FYM plus 50% N through chemical fertilizer (1/2N-M+1/2N-CF), FYM plus chemical fertilizer (MNPK) and FYM alone (M). We used the LOC content and CMI value to assess the effects of long-term combinations of FYM and chemical fertilizers at different rates on the SOC pool in various soil layers (0–20, 20–40, 40–60, 60–80, 80–100 cm) and to identify the most suitable integrated treatment. The results showed that the application of organic fertilizer generally increased the SOC content, the LOC fraction, and the CMI values in different layers, especially the surface layer, compared to the CK and NPK fertilization treatments. The SOC content and LOC fraction decreased with increasing soil depth. The significant relationship between the LOC fraction, CMI value, LOC available ratio of carbon (LOC-AR), and soil parameters showed that these values can be used to sensitively assess soil quality and SOC changes in the system. Considering the comprehensive effects on the SOC content, LOC fraction, CMI value, AR value, etc., the 1/4N-M+3/4N-CF and 1/2N-M+1/2N-CF treatments showed the greatest influence on carbon sequestration and soil productivity; therefore, these could be the best options for maize cropping systems in this region. [ABSTRACT FROM AUTHOR]

Purpose: The partial substitution of mineral fertilizers with straw in agricultural soils could help to control soil acidification, reduce the risk of eutrophication from agricultural runoff, and increase the utilization efficiency of straw. However, the effects of such coupled practices on greenhouse gas (GHG) emissions and production yields in vegetable fields are not clear. Therefore, the objectives of this study were to (1) understand methane (CH4) and nitrous oxide (N2O) emissions in response to the same amounts of straw return with varied amounts of mineral fertilizers, and (2) to identify a solution which could better coordinate GHG emissions, vegetable production yield, and the utilization of agricultural straw following disposal. Materials and methods: We conducted four-season (lettuce-cabbage-chili-lettuce) vegetable cultivation for 1 year using a control treatment (CT), mineral fertilization only (F), and four mineral fertilization treatments plus maize straw (FS, 0.7FS, 0.6FS, and 0.5FS). We then examined seasonal changes of CH4 and N2O fluxes, CH4 and N2O cumulative emissions, soil organic carbon (SOC), nitrate nitrogen (NO3−-N) and ammonium nitrogen (NH4+-N) content, vegetable yields, global warming potential (GWP), greenhouse gas intensity (GHGI), and N2O emission factors (EF). Results and discussion: Compared to the F treatment, the application of maize straw increased the N2O flux significantly in the FS, 0.7FS, 0.6FS, and 0.5FS treatments. In treatments with added straw, the reduced application of mineral fertilizer led to a reduction in the cumulative N2O emission; this was due to the reduced content of NO3−-N content. The lowest CH4 flux and cumulative CH4 emission were observed in the 0.7FS treatment; this may be due to a form of competitive oxidation between CH4 and NH4+-N from urea. Furthermore, the application of maize straw in combination with a full dose of mineral fertilizers led to high GWP and GHGI values, which showed increases of 88.7% and 78.8%, respectively, in comparison with the F treatment. When taking SOC storage variations into account, which were caused by straw decomposition during cultivation, we identified a negative net GHGI (NGHGI) value (− 0.0448 kg CO2-eq kg−1 yield) in the 0.7FS treatment. This indicated that the NGHGI had decreased by 116.2% relative to the F treatment when based on similar vegetable yields. Conclusions: Straw combined with 70% mineral fertilizer led to better GHG emissions and vegetable yield when taking into account the carbon sequestration and decomposition caused by the addition of straw. [ABSTRACT FROM AUTHOR]

Afterglow materials possess the remarkable capability to harness the energy and subsequently emit light after irradiation is turned off. Owing to their extraordinary ultralong lifetime, afterglow materials have garnered significant interest across various domains such as sensing, optoelectronics, bioimaging, and information encryption. However, these materials typically exhibit temperature sensitivity, rendering their afterglow emission susceptible to efficient quenching at room temperature. Consequently, this study presents herein a straightforward, simple, and universal approach for synthesizing metal-free carbon dots (CDs) endowed with thermally activated delayed fluorescence (TADF) characteristics at room temperature. In this study, TADF-CDs were simply synthesized by pyrolyzing boronic acid (BA) and urea at 500 ℃ for 3 h. Benefiting from the multi-confined effects facilitated by the robust structure of BA matrix, in conjunction with the co-doped heteroatoms of nitrogen and boron, the resultant TADF-CDs manifest remarkably prolonged afterglow TADF emission, characterized by a calculated lifetime of 184.64 ms; moreover, the blue afterglow emission remains perceptible to the naked eye for more than 6 s. The attributes of TADF-CDs were comprehensively elucidated through rigorous characterization, and the universality of the approach was corroborated through experimentation involving fourteen control CDs. Leveraging their distinctive TADF attributes, the prepared TADF-CDs were subsequently employed in advanced applications such as anti-counterfeiting and information encryption. [ABSTRACT FROM AUTHOR]

Lodging is a major constraint to maize productivity and harvesting mechanization in the North China Plain. EDAH (contains ethephon and diethyl aminoethyl hexanoate) is a novel growth regulator, which had been proved to enhance maize lodging resistance and increase yield, especially under high plant density. However, lodging still happens when recommended dose of EDAH was foliar sprayed in many previous reports. Therefore, a field experiment with normal dose (T1) and increased dose (T2) of EDAH was conducted to further enhance maize lodging resistance under different plant densities. Results indicated that T2 significantly reduced plant height and ear height, and obviously increased bending strength (P < 0.05), i.e., increasing EDAH dose more obviously enhanced maize lodging resistance. Concurrently, EDAH distinctly inhibited maize growth which resulted in lower leaf area index (LAI) and leaf area duration (LAD) after silking. However, both leaf photosynthetic rate and chlorophyll content during filling stage were not significantly (P > 0.05) changed by EDAH. Consequently, maize grain yields under T1 and T2 were reduced by 3.2–8.5% and 10.9–13.6% under optimized density (7.5 plants m2−) in this study, respectively. Nevertheless, EDAH did not reduce maize yield under high density (9.0 plants m2−) due to relative high LAI (5.3–5.6). We concluded that high dose EDAH further enhanced lodging resistance with reduced grain yield under optimized density, but maintained grain yield under high plant density. Results of this study provided a critical strategy to lower lodging risk and increase maize grain yield. [ABSTRACT FROM AUTHOR]