Understanding the immiscible displacement mechanism in porous media is vital to enhancing the hydrocarbon resources in the oil and gas reservoir. Improving resource recovery requires quantitatively ...characterizing the effect of wettability heterogeneity on the immiscible displacement behaviors at the pore scale, which can be used to predict the displacement distribution of multiphase fluids and evaluate the optimal wettability strategy in porous media. The heterogeneity of fluid wettability in a natural rock makes it extremely hard to directly observe the fluid displacement behaviors in the reservoir rocks and quantify the sensitivity of preferential displacement path and displacement efficiency to wettability distribution. In this study, the phase-field model coupling wettability heterogeneity was established. The gas-water two-phase displacement process was simulated under various wettability distributions and injecting flux rates in a complex pore structure. The effect of wettability heterogeneity on immiscible displacement behavior was analyzed. The results indicated that wettability heterogeneity significantly affects the fluid displacement path and invasion patterns, while the injecting flux rate negatively influences the capillary–viscous crossover flow regime. The continuous wetting patches enhanced the preferential flow and hindered displacement, whereas the dalmatian wetting patches promoted a higher displacement efficiency. The results of the fractal dimensions and specific surface area also quantitatively show the effects of wettability distribution and heterogeneity on the complexity of the two-phase fluid distribution. The research provides the theoretical foundation and analysis approach for designing an optimal wettability strategy for injecting fluid into unconventional oil and gas reservoirs.
Background
There is a sex disparity in papillary thyroid cancer (PTC). Male sex is associated with a higher likelihood of advanced stage disease. This study aimed to examine the significance of sex ...for extranodal extension (ENE) in PTC.
Methods
We reviewed the data of PTC patients who had undergone initial surgical resection from July 2012 to December 2014 (
N
= 1531). The effects of sex and other clinicopathological factors on ENE were investigated.
Results
Of 1531 patients identified, 377 (24.6%) were male, 816 (53.3%) had positive nodes, and 256 (16.7%) had ENE. Compared with female patients, male patients had a higher risk of ENE (
P
< 0.001). Multivariable analysis of clinicopathological factors revealed that male sex (odds ratio OR, 1.98; 95% confidence interval CI, 1.37–2.87;
P
< 0.001), age older than 60 years (OR, 1.93; 95% CI, 1.08–3.35;
P
= 0.023), extrathyroidal extension (OR, 3.52; 95% CI, 2.42–5.14;
P
< 0.001), bilateral multifocality (OR, 2.18; 95% CI, 1.53–3.13;
P
< 0.001), and more positive nodes were significantly associated with increased risk of ENE. Patients with 6–10 positive nodes were 16.45-fold higher to have ENE than patients with 5 positive nodes or less (95% CI, 11.07–24.68;
P
< 0.001).
Conclusion
Male PTC patients had a higher risk of ENE than female. Sex was an independent predictor of ENE. The underlying mechanism needs to be investigated further.
The pore network is an approximate representation of the void space of porous materials, such as rocks and soil, via pores (corresponding to large cavities) and throats (narrow constrictions). During ...extraction of networks from real void space, ambiguous definitions or determinations of pores and throats may cause significant errors in the prediction of single/multi‐phase transport properties. Meanwhile, the pore‐throat segmentation needs to exclude non‐physical parameters as much as possible. In this work, we propose a pore‐throat segmentation method based on local hydraulic resistance equivalence between the real void space and the simplified pore‐throat geometry. Each pore‐throat interface is carefully determined at the position where the simplified tubes preserve the local hydraulic resistance of the real space best. This local segmentation method ensures equivalency between extracted pore network and real pore space without any empirical or non‐physical parameters. After validations of accuracy and reliability by benchmarks, this method is applied to real porous materials including spherical pack, sand pack, sandstone, limestone, and carbonate. The single/two‐phase transport properties predicted by the new method agree well with the experimental data and the direct simulation results. The proposed method improves the accuracy of pore network model (PNM) predictions significantly with a slight increase in computational cost. This local pore‐throat segmentation method may enhance the capability of PNM for more complicated applications.
Key Points
A pore‐throat segmentation method is proposed based on local hydraulic resistance equivalence
The reliability and accuracy are validated via various benchmark cases
The proposed method accurately predicts single/two‐phase transport properties
Background
The purpose of this study was to explore the impact of the lymph node ratio on prognosis in papillary thyroid cancer patients with lymph node metastasis.
Methods
Data from papillary ...thyroid cancer patients with positive nodes who were initially treated at our institution during 2015–2016 were analysed. Univariate and multivariate Cox proportional hazard models were adopted to predict prognostic factors. A receiver operating characteristic (ROC) curve was used to find the best cut-off value of the lymph node ratio (LNR). Kaplan–Meier curves were used to show the relationship between the LNR in the lateral neck and recurrence-free survival.
Results
The median follow-up time was 64.6 months, and recurrence occurred in 16 of 662 patients (2.27%). Univariate analysis showed that male sex, primary tumour size (>17 mm), visible extrathyroidal extension, LNR in the central neck (>0.5), LNR in the lateral neck (>0.10), and visible extranodal extension were significantly correlated with recurrence-free survival (RFS) (
p
< 0.05). Multivariate analysis using the Cox proportional hazards model showed that the LNR in the lateral neck was an independent risk factor for RFS (
p
= 0.039; HR 14.76).
Conclusion
The LNR in the lateral neck was an independent risk factor for recurrence-free survival. For patients with a high lymph node ratio in the lateral neck, more frequent follow-up might be needed.
Purpose
Lymph node metastasis is common in patients with papillary thyroid cancer (PTC). Some metastatic lymph nodes may present extranodal extension (ENE). The clinical role of ENE in PTC has yet to ...be clearly identified. We evaluated macroscopic ENE as a potential prognostic indicator of lung metastasis in PTC.
Patients and methods
We identified 1140 consecutive patients who had PTC initially resected at our cancer center. Clinical data and pathological results were reviewed. Univariate and multivariate logistic regression analyses were used to figure out the association between clinicopathological variables and lung metastasis.
Results
In this cohort, 51.7% of PTC patients had lymph node metastasis; 10.4% had macroscopic ENE positive nodes; 2.3% had lung metastasis. In patients with lymph node metastasis, the average number of positive nodes was 5.10 ± 4.91. Multivariable analysis of clinicopathological factors revealed that extrathyroidal extension (odds ratio OR, 3.57; 95% CI, 1.41–9.04), macroscopic ENE (OR, 7.08; 95% CI, 2.54–19.74), and number of positive nodes were significantly associated with lung metastasis. Compared with 0–3 positive nodes, 7–9 positive nodes denoted a moderate risk of lung metastasis (OR, 4.53; 95% CI, 1.03–19.85). And 10 positive nodes or more indicated a high risk of lung metastasis (OR, 9.63; 95% CI, 2.65–35.02).
Conclusion
Macroscopic ENE could serve as a strong independent prognostic factor of lungmetastasis in PTC. More attention should be paid to patients with ENE positive nodes duringfollow-up.
Our goal was to analyze the incidence of level VI metastasis in previously untreated oral squamous cell carcinoma (SCC) patients and their clinicopathological and prognostic characteristics.
Oral SCC ...patients with level VI metastasis were retrospectively enrolled, and their demographic and pathologic features as well as their survival data were descriptively analyzed.
A total of 13 cases from 1875 patients were included, all patients had SCC at the floor of mouth (SCCFOM). Eight (61.5%) patients had a pT4 tumor, and all patients had a pathological N3 neck with multiple positive lymph nodes. Adverse pathologic features were present in 100% of the patients. The size of the metastatic foci in level VI ranged from 2.6 cm to 4.5 cm with a mean value of 3.2 cm, and 5 patients showed a soft tissue deposit with no lymph node component. Recurrence occurred in all patients, and 11 patients died of uncontrolled cancer within 5 years after surgery.
Level VI metastasis in primary oral SCCFOM is rare, and its prognosis is poor.
An intelligent fault diagnosis method of rolling bearings based on a depth feature fusion network was proposed to solve the problems of a single original signal, large noise interference and ...difficult diagnosis of varying working conditions of rolling bearings. Using various transform domain signals can make the input contain comprehensive information, extract useful fault features, and conduct feature fusion through the attention mechanism feature fusion method to enhance the ability to obtain effective features. In addition, an improved dense network integrates the pooling layer with dense blocks and introduces a multi-scale convolution kernel and squeeze excitation module. It can promote feature reuse, reduce the dimensions of the feature map, and automatically measure the importance of the weight of each feature channel, enhancing the useful features of the current task and suppressing useless features. Hence, the model has an optimum feature extraction capability. The bearing dataset of Case Western Reserve University was selected to verify the fault diagnosis ability of the proposed method. The recognition accuracy rates under ideal, anti-noise and generalization tests were 99.75%, 97.81% and 96.88%, respectively. The recognition accuracy rate was higher than that of the other depth learning models. Experiments and comparative analysis showed that the proposed method has good anti-noise and generalization abilities compared to traditional methods.
Background
Central neck metastasis (CNM) is common in patients with papillary thyroid carcinoma (PTC). However, the prediction of CNM risk remains poorly defined, especially for patients with ...clinically negative lymph nodes. We developed a preoperative clinical nomogram to predict CNM risk in patients with clinical T1-2N0 (cT1-2N0) PTC.
Methods
Data from 436 patients with unifocal cT1-2N0 PTC were available. We analyzed the association between preoperative variables and CNM using univariate and multivariate logistic regression and developed a clinical nomogram based on the multivariate regression model. The nomogram was validated externally using an independent dataset.
Results
The CNM rate was 25.5%. Three clinical variables were associated with CNM, including age, gender, and tumor size. We built a CNM nomogram integrating these three variables. It had a poor index of internal discrimination (C-index, 0.655; 95% CI 0.596–0.715) and a poor index of external discrimination (C-index, 0.690; 95% CI 0.611–0.769).
Conclusions
We developed a preoperative nomogram to quantify the risk of CNM in unifocal cT1-2N0 PTC patients. However, our data showed that preoperative clinical parameters were not able to accurately predict the likelihood of CNM. Other variables need to be investigated to improve the prediction capability of this nomogram.
Accurate understanding and quantitative characterization of the three-dimensional (3D) immiscible water–oil two-phase displacement process and of the factors that affect this process in porous ...reservoir rocks are prerequisites for the enhancement of petroleum recovery efficiency. To meet these prerequisites, it is crucial to directly visualize and quantify the pore scale physics and dynamic evolution of the water–oil two-phase displacement behavior. However, engineering activities, such as borehole drilling, reservoir fracturing, and oil recovery, can cause geostress redistribution in petroleum reservoirs and drastically change the 3D pore structures of reservoir rocks. This makes it difficult to apply conventional experimental techniques and analytical models to directly reveal and evaluate the 3D immiscible fluid displacement in reservoir rocks during pore structure deformation. In this study, we used X-ray computed tomography, integrated with triaxial loading techniques, to capture in situ the immiscible water–oil displacement and oil trapping inside 3D pore spaces during the deformation induced by various geostresses. An additive manufacturing or 3D printing (3DP) technology was applied to replicate the transparent models of actual porous rocks, facilitating the representation and quantification of pore space deformation and the dynamic process of water–oil displacement and oil trapping. Pore scale displacement behaviors (including water sweeping, fingering effects, preferential flow paths, and oil trapping) and their evolution and pore structure deformation with varying geostress were directly visualized and quantified. The relationships between the characteristics of the deformed structures, water–oil displacement efficiency, and effective geostress changes were formulated. The results indicate that stress-induced pore structure deformation has an evident impact on the 3D water–oil displacement behavior and efficiency. A comparison of the 2D and 3D water-oil displacement behaviors indicates that the 3D model predicts a more realistic displacement performance, whereas the residual oil saturation is overestimated in a 2D pore system owing to the truncation of pore connectivity in the third dimension. This study provides a method for directly visualizing and quantifying the effects of geostress-induced pore deformation on the 3D water–oil displacement in porous reservoirs; this method can help draft a strategy to enhance petroleum recovery.
The lymph node posterior to the right recurrent laryngeal nerve (LN-prRLN) is an important part of the central lymph nodes (LNs). We aimed to explore the rate and predictors of LN-prRLN metastasis in ...cN0 papillary thyroid carcinoma (PTC) located at the left thyroid lobe.
Patients with surgically treated primary left lobe PTC were retrospectively enrolled. The metastatic distribution of LN-prRLN and postoperative complications were assessed. The association between LN-prRLN metastasis and clinicopathological variables was evaluated by univariate and multivariate analyses.
A total of 857 patients were included for the analysis. Central LN metastasis was noted in 310 (35.3%) cases. The most (27.6%) and least (1.7%) commonly involved LNs were the left paratracheal LN and the LN-prRLN. In the univariate analysis, the tumor size, multifocality, the extent of extrathyroidal extension (none
macroscopic
macroscopic maximal), and perineural invasion were associated with positive LN-prRLN. In the multivariate analysis, tumor size of >40.0 mm and macroscopic maximal invasion were found as the only two independent predictors. Transient and permanent hypoparathyroidism were noted in 90 (10.2%) and 13 (1.5%) patients, respectively. Voice change was noted in 40 (4.6%) patients, and 20 patients recovered.
In cN0 PTC located at the left lobe, LN-prRLN metastasis was very uncommon. We found that LN-prRLN dissection is not required routinely, but should be performed if the tumor size is >40.0 mm and macroscopic maximal extrathyroidal extension is present.
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