Rayleigh waves in oil exploration seismic records usually have strong energy and are considered as noise, but Rayleigh waves also carry information about subsurface. In this paper, we process ...Rayleigh waves from a set of oil seismic data to detect underground structures of shear-wave velocity (vs) using multi-channel analysis of surface waves (MASW). Fundamental mode and higher order mode dispersion curves of the Rayleigh wave were automatically extracted by a modified phase shift method. We then use the genetic and damped least squares (DLS) joint inversion algorithm to inverse the dispersion curves and obtain a one-dimensional (1D) vs structure under each shot gather. Finally, all 1D vs structures were combined to create a 3.2 km long two-dimensional (2D) section, revealing a stratum structure down to 80 m depth. The results show that MASW technology successfully improves the use of oil seismic data, the automatic dispersion extraction method based on modified phase shift improves the efficiency of data processing, and the joint inversion algorithm reduces the dependence of the Rayleigh wave dispersion inversion on initial model.
•An automatic extraction method of dispersion curve is proposed.•A genetic-DLS joint inversion algorithm is used to obtain the vs structure.•The MASW technology successfully improved the utilization of oil seismic data.
Stick-slip vibration is a common phenomenon met in oil gas drilling, especially in the complex trajectory wells such as highly-deviated wells, it will cause the earlier failure of BHA (bottom hole ...assembly) and lower drilling efficiency. In this present paper, a finite element model of highly-deviated well, which consists of a drill string system, a borehole, a PDC bit (Polycrystalline Diamond Compact bit) and a rock model, is carried out to investigate the stick–slip vibration behaviors of drill bit and BHA. Besides, the torsional impact drilling method is proposed in the context to control the stick–slip vibration of BHA. The research results show that, the phenomenon of stick–slip vibration of BHA gradually weaken and disappear with the distance from the drill bit increases, and the stick–slip vibration mainly occurs at the BHA which near drill bit. The high frequency torsional impact drilling method can reduce the resistance torque of the bit by 34.71%, and increase the drilling depth by about 58.28%. It can effectively improve the drilling efficiency of the bit, making the rotation of drill bit becomes relatively more stable, and reducing or even eliminating the stick–slip vibration. These results lead to an enhanced understanding of stick–slip vibration behaviors of drill bit and BHA in highly-deviated wells, and provide the basis for improving the drilling efficiency.
Accurate tritium transport properties of prospective tritium permeation barriers (TPBs) are essential to tritium systems in fusion reactors. By passing a temperature and rate-controlled sweeping gas ...over specimen surfaces to carry the permeated tritium to an ion chamber, the gas-driven permeation of tritium has been performed on 321 type stainless steel containers with Al2O3/FeAl barriers, to determine the T-permeation resistant performance and mechanism of the barrier. The tritium permeability of the Al2O3/FeAl coated container was reduced by 3 orders of magnitude at 500–700 °C by contrast with that of the bare one, which meets the requirement of the tritium permeation reduction factor (PRF) of TPBs for tritium operating components in the CN-HCCB TBM. The Al2O3/FeAl barrier resists the tritium permeation by the diffusion in the bulk substrate at a limited number of defect sites with an effective area and thickness, suggesting that the TPB quality is a very important factor for efficient T-permeation resistance.
•T-permeation has been measured on bare and coated type 321 SS containers.•Al2O3/FeAl coating give a reduction of T-permeability of 3 orders of magnitude.•Mechanism of Al2O3/FeAl barrier resisting T-permeation has obtained.•Quality of TPB is a very important factor for efficient T-permeating reduction.
A theoretical model of ductile-brittle transition considering the cutter-rock friction was established, and the cutting force, mechanical specific energy (MSE), morphology of cutting chips and ...ductile-brittle failure transition mechanism of four different specially-shaped cutters were investigated through rock cutting tests. Furthermore, the 3D heterogeneous granite cutting numerical simulation models of 12 kinds of specially-shaped cutters and PDC bits were established by using the finite-discrete element method, and the problems such as the cutting force response, cutting chips formation, and MSE change rules were reproduced, as well as the influence of cutter shapes on drilling efficiency of PDC bits. The results indicate that there exists a critical cutting depth of ductile-brittle transition. Moreover, the critical cutting depth, MSE, footage and other parameters of 12 kinds of cutters were compared to provide a certain basis for the selection of drilling cutters, design optimization of drilling bits and the optimization of drilling parameters.
Background The surgical management and outcomes of renal cell carcinoma (RCC) with venous tumor thrombus (VTT) have been reported in limited sample size, and there remain discrepancies over the ...factors that influence oncologic outcomes after radical nephrectomy with thrombectomy (RNTE). The aim of the study was to analyze the outcomes of the patients with RCC with VTT in our institution and identify the independent prognostic factors. Methods Patients with RCC with VTT were enrolled for the study from February 2015 to December 2018. All patients underwent RNTE. Clinical data were compared using Mann-Whitney U test and the chi-square test for continuous and categorical variables respectively. Survival analysis was estimated using the Kaplan-Meier method. Univariable and multivariable survival analyses were performed using Cox regression model. Results 121 patients (91 men & 30 women) were identified with a median age of 60 years. VTT level was 0 in 25 patients, I in 20, II in 50, III in 12 and IV in 14. The median follow-up time was 24 months. During the follow-up period, 51 (42%) patients died and 69 (57%) patients experienced recurrence or metastasis. The 3-year and 5-year over-all survival (OS) were 58 and 39%. Among the several factors examined, positive lymph node (P = 0.016), metastasis at surgery (P = 0.034), tumor necrosis (P = 0.023) and sarcomatoid differentiation (P < 0.001) were demonstrated as independent significant risk factors on multivariable analysis. Conclusion The OS was poor for patients with RCC with VTT. Rather than VTT level, positive lymph node, metastasis at surgery, tumor necrosis and sarcomatoid differentiation were independent prognostic predictors. Keywords: Renal cell carcinoma, Venous tumor thrombus, Thrombectomy, Overall survival, Prognosis
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In rock mass cutting, the two main failure modes are ductile failure and brittle failure, and it strongly influence the rock breaking efficiency of the drilling bit. As such, investigation into the ...ductile–brittle failure transition (DBT) mechanism during rock cutting is crucial, especially for hard brittle rock. In the present study, a discrete-finite element model of heterogeneous granite was created and used for rock cutting experiments, so as to reproduce the cutting force and rock chip formation process. In addition, to interpret the DBT mechanism of granite cutting, theoretical models of mechanical specific energy (MSE) considering damaged zone, mean value of equivalent stiffness degradation (SDEG) and self-interlocking coefficient were developed. The study found that the cutting force bilinearly increases with the increase of cutting depth, and the cutter would crush the rock beneath the cutter tip. The average equivalent rock SDEG of the crushed zone reflects the damage value of rock chips. The critical transition depth (CTD) obtained using the theoretical models were almost equal. The self-interlocking of the crushed zone led to the secondary crushing of rock chips, which was the primary cause of ductile failure. Further, the self-interlocking was more obvious at large back rake angles and small depths, which consumed more energy. Reducing the self-interlocking of the crushed zone and increasing the ratio of brittle failure could effectively improve the rock breaking efficiency. The present study provides new insights from numerical simulations of DBT in rock cutting, and provides a basis for optimizing the cutter parameters of the drill bit.Article highlightsA discrete-finite element model for heterogeneous granite according to Voronoi tessellation was established.Theoretical models of new MSE is proposed, which considers the damaged zone beneath the cutter tip.The characteristics of DBT from the perspective of cutting force, boundary effect, and rock chips morphology were reproduced numerically and experimentally.The causes of DBT of hard brittle granite were analyzed—self-interlocking and secondary crushing of chips.
BACKGROUND: Non-suicidal self-injury (NSSI) is a vital public concern around the world, and it often starts in adolescence. Emotional neglect (EN) has been considered a distal risk factor for NSSI, ...but the effects of social anxiety symptoms (SA) and insomnia on this relationship have remained unclear. This study aimed to investigate the potential pathways from EN to NSSI, examining the role of SA and insomnia in this association.
One thousand three hundred thirty seven Chinese middle school students (M
= 13.040, SD = 0.981, 50.2% males) in China were enrolled in this cross-sectional study. Participants completed the Emotional Neglect sub-scale of Childhood Trauma Questionnaire (CTQ-SF), the Social Anxiety Scale for Adolescent (SAS-A), Athens Insomnia Scale (AIS) and non-suicidal self-injury assessment. Structural equation modelling (SEM) was used to test the possible mediation model among these variables.
231(17.3%) students reported NSSI history during last year and 322 (24.1%) participants reported experiences of EN. Students who experienced EN have higher rates of NSSI compared to students without EN history (29.2% vs 13.5%). EN, SA, insomnia and NSSI were positively related to each other. Furthermore, both SA and insomnia played a mediating role in the relationship between EN and NSSI, the series mediating effect of SA and insomnia on this association was also significant after controlling for demographics. Indirect effects accounted for 58.26% of the total effects (EN → NSSI).
Our study revealed that EN was associated with NSSI, SA and insomnia play indirect roles in the association between EN and NSSI. The findings of our research may have implications for clinicians, families, and schools in their efforts to lower the risk of NSSI in adolescents.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Hepatoma-derived growth factor (HDGF) is commonly over-expressed and plays critical roles in the development and progression in a variety of cancers. It has previously been shown that HDGF is ...overregulated in prostate cancer cells compared to normal prostate cells, which is correlated with cellular migration and invasion of prostate cancer. Here, the molecular mechanisms of HDGF in prostate cancer is investigated. It is shown that HDGF knockdown reduces prostate cancer cellular migration and invasion in both androgen-sensitive LNCaP cells and androgen-insensitive DU145 and PC3 cells. Furthermore, Western blot analysis reveals that HDGF knockdown inhibits epithelial-mesenchymal transition (EMT) of prostate cancer cells by upregulation of protein E-cadherin and downregulation of proteins N-cadherin, Vimentin, Snail and Slug. In addition, mechanistic studies reveal that proteins MMP2 and MMP9 are down-regulated. In conclusion, our data suggested that HDGF knockdown inhibits cellular migration and invasion in vitro of prostate cancer via modulating epithelial-mesenchymal transition (EMT) signaling pathway, as well as MMP2 and MMP9 signaling pathway. These results supported that HDGF is a relevant protein in the progression of prostate cancer and may serve as a potentially therapeutic target for prostate cancer as well as its downstream targets.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Glioma is regarded as an aggressive lethal primary brain tumor. Jumonji domain containing 1C (JMJD1C) is a H3K9 demethylase which participates in the progression of various tumors, but its specific ...function and underlying mechanism in glioma development remain undefined, which is the purpose of our work. We initially assessed JMJD1C expression in glioma tissues and cells using the assays of RT‐qPCR and immunohistochemistry. Meanwhile, the H3K9 level at the microRNA (miR)‐302a promoter region was measured by chromatin immunoprecipitation assay, while luciferase‐based reporter assay was performed for validation of the binding affinity between miR‐302a and methyltransferase‐like 3 (METTL3). The effect of METTL3 on suppressor of cytokine signaling 2 (SOCS2) was subsequently analyzed by MeRIP‐RT‐qPCR. Finally, a xenograft tumor model was established in nude mice, followed by measurement of tumor‐associated macrophages using flow cytometry. JMJD1C was poorly expressed in glioma tissues. Furthermore, JMJD1C increased miR‐302a expression through promoting H3K9me1 demethylation at the miR‐302a promoter region. miR‐302a was identified to target METTL3, which could inhibit SOCS2 expression via m6A modification. JMJD1C promoted M1 macrophage polarization and suppressed the growth of glioma xenografts through the miR‐302a/METTL3/SOCS2 axis both in vivo and in vitro. In conclusion, JMJD1C could enhance M1 macrophage polarization to inhibit the onset of glioma, bringing a new insight into the contribution of JMJD1C to the pathobiology of glioma, with possible implications for targeted therapeutic method.
Our results indicate that JMJD1C enhances M1 macrophage polarization to inhibit the onset of glioma, which brings a new insight for the contributions of JMJD1C to the pathobiology of glioma.
Capillary hemangiomas, usually found in skin and mucosal tissues, are rarely encountered within the spinal cord, presenting a significant diagnostic challenge. We report a rare case of intradural ...extramedullary capillary hemangioma at the conus medullaris in a 66-year-old female patient. Our initial diagnosis leaned towards a cystic hemangioblastoma based on MRI findings due to the presence of cystic formation with an enhanced mural nodule. However, surgical exploration and subsequent pathological examination revealed the lesion as a capillary hemangioma. To the authors' knowledge, this case may represent the first documented instance of a spinal capillary hemangioma that mimics a cystic hemangioblastoma.
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