Micro-nano scales flowing simulation in shale gas

The storage space of shale reservoir is mainly composed of complicated nanoscale pore, in which the gas exists in the form of absorbed gas and free gas. Due to the complicated pore structure and various gas storage states, gas flowing in the pore space is affected by multiple transport mechanisms including adsorption, desorption, Darcy flow, slippage and diffusion, etc. Therefore, a comprehensive research on the effects of transport mechanisms on shale gas flow is the key to study the shale gas migration rule, evaluate production capacity, and make reasonable development plan. Please download the full abstract below

A Contextual Fire Detection Algorithm for Simulated HJ-1B Imagery

The HJ-1B satellite, which was launched on September 6, 2008, is one of the small ones placed in the constellation for disaster prediction and monitoring. HJ-1B imagery was simulated in this paper, which contains fires of various sizes and temperatures in a wide range of terrestrial biomes and climates, including RED, NIR, MIR and TIR channels. Based on the MODIS version 4 contextual algorithm and the characteristics of HJ-1B sensor, a contextual fire detection algorithm was proposed and tested using simulated HJ-1B data. It was evaluated by the probability of fire detection and false alarm as functions of fire temperature and fire area. Results indicate that when the simulated fire area is larger than 45 m2 and the simulated fire temperature is larger than 800 K, the algorithm has a higher probability of detection. But if the simulated fire area is smaller than 10 m2, only when the simulated fire temperature is larger than 900 K, may the fire be detected. For fire areas about 100 m2, the proposed algorithm has a higher detection probability than that of the MODIS product. Finally, the omission and commission error were evaluated which are important factors to affect the performance of this algorithm. It has been demonstrated that HJ-1B satellite data are much sensitive to smaller and cooler fires than MODIS or AVHRR data and the improved capabilities of HJ-1B data will offer a fine opportunity for the fire detection

A study of relative permeability for transient two-phase flow in a low permeability fractal porous medium

In this paper, a relative permeability prediction method considering the effects of capillary pressure and threshold pressure gradient in a low permeability fractal porous medium is established and analyzed based on the fractal approximation model that porous medium consist of a bundle of tortuous capillaries. With this method, every parameter has clear physical meaning without empirical constants, and the model's predictions have a good agreement with experimental data. In addition to this, it makes some discussions that how the characteristic parameters (such as tortuosity fractal dimension, pore fractal dimension, ratio of minimum-maximum capillaries diameters and threshold pressure gradient) influence the relative permeability. This study may be conducible to a better understanding of the mechanism for transient two-phase flow in the low permeability fractal porous medium.Cited as: Li, Z., Duan, Y., Fang, Q., Wei, M. A study of relative permeability for transient two-phase flow in a low permeability fractal porous medium. Advances in Geo-Energy Research, 2018, 2(4): 369-379, doi: 10.26804/ager.2018.04.0

Cooperation-based sperm clusters mediate sperm oviduct entry and fertilization

Sperm cooperation has been observed in multiple species, yet its existence and benefit for reproductive success in mammals remains underexplored. Here, combining tissue-clearing with deep three-dimensional imaging, we demonstrate that postcopulatory mouse sperm congregate into unidirectional sperm cooperative clusters at the utero-tubal junction (UTJ), a key physical barrier for passage into the oviduct. Reducing sperm number in male mice by unilateral vasoligation or busulfan-treatment impairs sperm cluster formation and oviduct entry. Interestingly, sperm derived from Tex101-/- mouse has normal number, motility and morphology, yet they cannot form sperm cluster and fail to pass through the UTJ, which is at least in part due to the altered tail beating pattern of the Tex101-/- sperm. Moreover, Tex101-/- sperm's defect in oviduct entry cannot be rescued by the presence of wild-type (WT) sperm in the same uteri by sequential mating, suggesting sperm cooperative cluster as an essential behavior contributing to male fertility, which could be related to human infertility or subfertility

miR-155-5p is Negatively Associated with Acute Pancreatitis and Inversely Regulates Pancreatic Acinar Cell Progression by Targeting Rela and Traf3

Background/Aims: Acute pancreatitis contributes to high mortality in pancreatitis patients, and miRNAs play a vital role in the development of acute pancreatitis (AP), however, its precise biological role remains largely elusive. Methods: To clarify the potential mechanisms of miRNAs in AP, we built mouse models of mild acute pancreatitis (MAP) and moderate/ severe acute pancreatitis (SAP). MiRNA microarray analysis and Real-time quantitative PCR (qRT-PCR) were used to analyze the expression of miRNA in MAP/SAP. TargetScan software, dual-luciferase gene reporter assays and Western blotting were used to assess the target genes of miR-155-5p in AP. Results: miR-155-5p was significantly decreased in MAP/SAP mice compared to controls. In pancreatic acinar AR42J cells transfected with miR-155-5p mimic, the expression of Rela and Traf3 notably decreased in both the caerulein- and TLC-S-induced groups compared with the negative control (NC); however, the expression of Rela and Traf3 notably increased after transfection with miR-155-5p inhibitor. Combined analysis using the TargetScan software and dual-luciferase gene reporter assays indicated that Rela and Traf3 were both targeted by miR-155-5p. Meanwhile, the expression of Ptgs2 also decreased after transfection of the AR42J cells with miR-155-5p mimic. The opposite results were found when miR-155-5p inhibitor was transfected into the AR42J cells. In addition, we treated caerulein- and TLC-S-induced AR42J cells with the Rela inhibitor helenalin and found that the expression of Rela, Traf3 and Ptgs2 decreased compared with the NC, while the expression of miR-155-5p did not show any significant difference. Furthermore, we found that miR-155-5p was significantly down-regulated in pancreatitis patients. Conclusion: miR-155-5p inversely regulated AP development through the Rela/Traf3/Ptgs2 signaling pathway

Mini percutaneous nephrolithotomy is a noninferior modality to standard percutaneous nephrolithotomy for the management of 20-40 mm renal calculi: A Multicenter randomized controlled trial

Background: High quality of evidence comparing mini percutaneous nephrolithotomy (mPNL) with standard percutaneous nephrolithotomy (sPNL) for the treatment of larger-sized renal stones is lacking. Objective: To compare the efficacy and safety of mPNL and sPNL for the treatment of 20–40 mm renal stones. Design, setting, and participants: A parallel, open-label, and noninferior randomized controlled trial was performed at 20 Chinese centers (2016–2019). The inclusion criteria were patients 18–70 yr old, with normal renal function, and 20–40 mm renal stones. Intervention: Percutaneous nephrolithotomy PNL was performed using either 18 F or 24 F percutaneous nephrostomy tracts. Outcome measurements and statistical analysis: The primary outcome was the one-session stone-free rate (SFR). The secondary outcomes included operating time, visual analog pain scale (VAS) score, blood loss, complications as per the Clavien-Dindo grading system, and length of hospitalization. Results and limitations: The 1980 intention-to-treat patients were randomized. The mPNL group achieved a noninferior one-session SFR to the sPNL group by the one-side noninferiority test (0.5% [difference], p < 0.001). The transfusion and embolization rates were comparable; however, the sPNL group had a higher hemoglobin drop (5.2 g/l, p < 0.001). The sPNL yielded shorter operating time (–2.2 min, p = 0.008) but a higher VAS score (0.8, p < 0.001). Patients in the sPNL group also had longer hospitalization (0.6 d, p < 0.001). There was no statistically significant difference in fever or urosepsis occurrences. The study's main limitation was that only 18F or 24F tract sizes were used. Conclusions: Mini mPNL achieves noninferior SFR outcomes to sPNL, but with reduced bleeding, less postoperative pain, and shorter hospitalization. Patient summary: We evaluated the surgical outcomes of percutaneous nephrolithotomy using two different sizes of nephrostomy tracts in a large population. We found that the smaller tract might be a sensible alternative for patients with 20–40 mm renal stones. This multicenter, parallel, open-label, and noninferior randomized controlled trial showed that mini percutaneous nephrolithotomy achieved noninferior stone-free rate with advantages of reduced blood loss, less postoperative pain, and shorter hospitalization. Mini percutaneous nephrolithotomy should be considered a sensible alternative treatment of 20–40 mm renal stones.grants from high-level development funding of Guangzhou Medical Universit

An investigation of the effects of crosslinking of collagen on cell/collagen-matrix interaction

Wound dressing plays an important role in wound recovery and collagen interacts with the human body in such a way that it has specific advantages compared to synthetic materials. The aim of the present study was to get an optimal crosslinking agent for collagen and so the mechanical, chemical and biochemical properties of crosslinked collagen materials were investigated. Fibroblast cells are important in the process of wound healing, so the interaction of human fibroblast cells with crosslinked collagen films were investigated as well. Collagen I was isolated from bovine achilles tendons and collagen films were formed using the isolated collagen I solution. Collagen films were crosslinked with glutaraldehyde (GA), genipin, hexamethylenediisocyanate (HMDC), 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) at the equal concentration of 0.02 M and these crosslinked collagen films were compared with uncrosslinked collagen films (control). The surfaces of the crosslinked films were investigated using scanning electron microscopy (SEM). There was observable fibre structure on GA- and genipin-crosslinked collagen films. The tensile strength, elongation at break and low strain modulus of the crosslinked collagen films were investigated. The results showed that GA-, genipin- and HMDC-crosslinked collagen films obtained higher tensile strength than the control. Elongation at break of all the crosslinked collagen films became lower than the control. GA- and genipin-crosslinked collagen films obtained higher low strain modulus than other crosslinked collagen films and the control. The denaturation temperatures of all crosslinked collagen films were significantly higher than the control and the denaturation temperatures of GA- and genipin-crosslinked films were much higher than those of HMDC- and EDC-crosslinked films. All the crosslinked collagen films were resistant to the digestion of collagenase. These results suggest that all the crosslinking agents are effective and GA- and genipin-crosslinked films obtained more extensive crosslinking. The interaction of crosslinked collagen films with fibroblast cells was investigated, e.g. adhesion, proliferation and migration of fibroblast cells. The results demonstrated that the control, genipin- and EDC-crosslinked collagen films were conducive to cell adhesion. Fibroblast cells on the control, genipin- and EDC-crosslinked collagen films were able to proliferate after 24 hours, with increased growth after 48 hours. The fibroblast cells on the control, genipin- and EDC-crosslinked collagen films migrated directionally. The cells on genipin-crosslinked film initiated directional migration earlier than those on control- and EDC-crosslinked films. In summary, genipin crosslinked collagen films show high denaturation temperature, higher tensile strength and good biocompatibility for fibroblast cells adhesion, proliferation and migration. Genipin should be regarded as a suitable crosslinking agent for reconstituted collagen for use in wound dressing

Modélisation numérique des distorsions résiduelles de soudage de structures minces

ST ETIENNE-ENS des Mines (422182304) / SudocSudocFranceF

A Novel Temperature Prediction Model Considering Stress Sensitivity for the Multiphase Fractured Horizontal Well in Tight Reservoirs

An accurate temperature profile of the multi-stage fractured horizontal well is the foundation of production profile interpretation using distributed temperature sensing. In this paper, an oil-water two-phase flow multi-stage fractured horizontal well temperature prediction model considering stress sensitivity effect and the Joule–Thomson effect is constructed. Based on the simulation calculation, the wellbore temperature variation under different formation parameters, water cuts, and fracture parameters is discussed. The wellbore temperature distribution in multistage fractured horizontal wells is affected by many factors. According to the principle of orthogonal experimental design, the difference between wellbore temperature and initial formation temperature is selected as the analysis condition. Sixteen groups of orthogonal experimental calculations are designed and conducted. By analyzing the experimental results, it is found that the fracture half-length, water production, and formation permeability are the main controlling factors of the wellbore temperature profile. Finally, the production profile of the well is determined by calculating the temperature profile of a tight oil well and fitting it to the measured data of distributed temperature sensing