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Drill-string vibrations occur frequently during drilling. Stick–slip vibration, a common form of vibration, reduces the rate of penetration and leads to bit wear and drill-string failure. The positive-displacement motor (PDM), as an important downhole dynamic drilling tool, is increasingly widely used in the field of oil and gas drilling, using hydraulic energy to output torque and speed. Field data have demonstrated that the combined drilling method of a PDM and polycrystalline diamond compact (PDC) bits can effectively alleviate stick–slip vibration; however, the effect is uneven and no research has yet been conducted on the mechanism by which PDM suppresses stick–slip vibration. In this study, the research status of tools for suppressing downhole vibrations is reviewed. A dynamic model of a multi-degree-of-freedom drill-string system with PDM is established, and the structural parameters in the model are calculated. The Runge–Kutta method is used to solve the model, and the influence of the PDM on stick–slip vibration is analyzed. Research has indicated that the output parameters of the PDM have a positive role in suppressing stick–slip vibrations, and that there is a critical value for eliminating these vibrations. The critical value is influenced by the drilling and output parameters of the PDM: the greater weight on the bit (WOB) will lead to a higher critical value; the greater the output parameter of the PDM, the lower the critical value. In addition, the output parameters of the PDM significantly change the correlation between the response parameters of the bit, which is the key to eliminate stick–slip vibration. [ABSTRACT FROM AUTHOR]

Abstract Copper complexes are hopeful anticancer drugs due to their multifacet biological properties and high biocompatibility. Inflammatory environment plays an important role in tumor progression and affects the body response to chemotherapeutic agents. A copper(II) complex CuLA with a phenanthroline derivative N-(1,10-phenanthrolin-5-yl)-nonanamide (L) and two aspirin anions (A) as the ligands was synthesized. CuLA effectively induces mitochondrial dysfunction and promotes early-apoptosis in SKOV-3 cells; moreover, it suppresses the expression of cyclooxygenase-2, a key enzyme involved in inflammatory response, in lipopolysaccharide stimulated RAW 264.7 cells. By contrast, the analogue complex CuL without aspirin ligand shows similar influences on cellular redox homeostasis and cell cycle progression but relatively low cytotoxic activity due to its mild effect on mitochondrial function; more importantly, it lacks inhibition to cyclooxygenase-2. The results demonstrate that CuLA inhibits cancer cells through dual pathways involving DNA damage and mitochondrial dysfunction. The introduction of aspirin not only enhances the antitumour efficacy but also reduces the inflammatory threat. Copper complexes with both antitumor and anti-inflammatory activities may represent a new type of multifunctional metal complexes in hope to be developed into novel metallodrugs. Graphical abstract An aspirin-tethered copper(II) complex exhibits significant cytotoxicity against cancer cells via DNA cleavage, mitochondria destruction and anti-inflammation pathways. Unlabelled Image Highlights • A copper(II) complex with derivatives of phenanthroline and aspirin was synthesized. • DNA, mitochondria, and cyclooxygenase-2 (COX-2) are potential targets for the complex. • The complex has a remarkable impact on mitochondrial function, apoptosis, and COX-2. • Cytotoxicity was realized via dual action of DNA damage and mitochondrial interference. • Aspirin endows the complex with antiinflammatory activity besides of anticancer effect. [ABSTRACT FROM AUTHOR]

Abstract: With different polarity responses, coumarin and 4,4‐difluoro‐4‐bora‐3a,4a‐diaza‐s‐indacene (BODIPY) were hybridised to construct polarity fluorescent sensors, CBDP and iso‐CBDP, to overcome the disadvantages of solvatochromic sensors in ratiometric polarity sensing. Only CBDP displayed an emission ratio (ICou/IBDP, coumarin to BODIPY emissions) that increased with an exponential dependence on medium relative permittivity over a wide polarity range (ϵr<57.9). This sensing ability of CBDP was not affected by medium pH; viscosity; and most intracellular species, especially reactive oxygen, nitrogen, and sulfur species. Apart from local cytoplasmic polarity quantification through lambda imaging, CBDP enables real‐time ratiometric imaging for intracellular polarity oscillation induced by oxidative stimulation. Ratiometric polarity flow cytometry was developed, for the first time, with CBDP, which demonstrated that a high concentration H2O2 induced cytoplasmic polarity enhancement, whereas pre‐incubation with N‐acetyl‐ l‐cysteine inhibited this effect. [ABSTRACT FROM AUTHOR]

Tumor metastasis and angiogenesis are the major obstacles in anticancer therapy. A series of phenanthroline copper(ii) complexes with different alkyl chains (CPTn, n = 1, 4, 6, 8) are synthesized and characterized. Cellular uptake and cytotoxicity assays reveal that the complex with longer chain length exhibits higher cellular Cu accumulation and stronger inhibition against the cancer cells. Both lipophilicity and structure influence the cellular uptake and cytotoxicity of CPTn. CPT8 is the most potent complex in this series. In addition to its promising anticancer activity, CPT8 displays remarkable anti-metastatic properties by inhibiting the migratory and invasive ability of ovarian cancer cells. Furthermore, it shows excellent anti-angiogenic activity in tube formation and spheroid sprouting of human umbilical vein endothelial cells. The vasculogenic mimicry assay confirms that CPT8 can inhibit the vascular channel formation of aggressive mouse melanoma cells. The production of reactive oxygen species (ROS), the expression of matrix metalloprotease (MMP-2), and the character of tumor cells are implicated in the cytotoxicity of CPTn. CPT8 is a typical example that demonstrates the versatility of copper(ii) complexes for cancer therapy through multiple pathways. [ABSTRACT FROM AUTHOR]

The article focuses on a study regarding strength model for layered rocks considering planes of weakness. It mentions the use of metamorphic rocks including schists, gneisses, and slates, and sedimentary rocks including sandstones, mudstones, and shales for strength model. It also mentions that rock strength typically varies as a function of the orientation angle between planes of anisotropy.

As a labile molecule with a short half-life, the true concentration of H2S in biological systems is controversial. H2S-producing enzymes are mainly in the cytosol. Probes that can image cytosolic H2S in real-time and accurately are sought after. An indol–coumarin fluorophore is an ideal scaffold for mitochondrial H2S imaging. By a simple (yet rational) structural modification, CouMa was constructed with the fluorophore for cytosolic H2S detection. CouMa responded to H2S within 3 min in a ratiometric way without interference from common bio-relevant species and pH. The probe could image changes in exogenous H2S level and fluctuations in endogenous H2S generation in MCF-7 cells. The increment and depression of nitric oxide-related H2S generation in the cytosol was monitored by CouMa. It could be a powerful tool to reveal crosstalk between these two transmitters, and to image H2S generation in the cytosol. The structural-modification strategy could be useful to regulate subcellular localization. [ABSTRACT FROM AUTHOR]

This paper aims to study the effect of cyclic heating and flowing-water cooling conditions on the physical properties of granite. Ultrasonic tests, gas measured porosity, permeability, and microscope observations were conducted on granite after thermal treatment. The results showed that the velocity of P- and S-waves decreased as the number of thermal cycles increased. The porosity increased with the number of the thermal cycles attained at 600 °C, while no apparent changes were observed at 200 and 400 °C. The permeability increased with the increasing number of thermal cycles. Furthermore, microscope observations showed that degradation of the granite after thermal treatment was attributed to a large network of microcracks induced by thermal stress. As the number of thermal cycles increased, the number of transgranular microcracks gradually increased, as well as their length and width. The quantification of microcracks from cast thin section (CTS) images supported the visual observation. [ABSTRACT FROM AUTHOR]

The most crucial task of petroleum geology is to explore oil and gas reservoirs in the deep underground. As one of the analysis techniques in petroleum geological research, rock thin section identification method includes particle segmentation, which is one of the key steps. A conventional sandstone thin section image typically contains hundreds of mineral particles with blurred boundaries and complex microstructures inside the particles. Moreover, the complex lithology and low porosity of tight sandstone make traditional image segmentation methods unsuitable for solving the complex thin section segmentation problems. This paper combines petrology and image processing technologies. First, polarised sequence images are aligned, and then the images are transformed to the HSV colour space to extract pores. Second, particles are extracted according to their extinction characteristics. Last, a concavity and corner detection matching method is used to process the extracted particles, thereby completing the segmentation of sandstone thin section images. The experimental results show that our proposed method can more accurately fit the boundaries of mineral particles in sandstone images than existing image segmentation methods. Additionally, when applied in actual production scenarios, our method exhibits excellent performance, greatly improving thin section identification efficiency and significantly assisting experts in identification. [ABSTRACT FROM AUTHOR]

Monofunctional Pt(II) complexes with potent efficacy to overcome the drawbacks of current platinum drugs represent a promising therapeutic approach for triple negative breast cancer (TNBC). A heterocyclic-ligated monofunctional Pt(II) complex PtL with a unique action of mode was designed and investigated. PtL induced DNA single-strand breaks and caused genomic instability in TNBC cells. Mechanism studies demonstrated that PtL disrupted lysosomal acidity and function, which in turn triggered lysosome-dependent cell death. Furthermore, PtL showed convincing suppression in the tube forming and cell migratory abilities against the metastatic potential of TNBC cells. The synthesis and investigation of PtL revealed its potential value as an anti-TNBC drug and extended the family of monofunctional Pt(II) complexes. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H2S) is an endogenous signaling molecule involved in various physiopathological processes; coumarin-based merocyanines have been successfully utilized for developing fluorescent H2S sensors. However, subtle changes in the chemical structure of merocyanines could induce distinct difference in the H2S sensing behavior. Investigation of the structure–property relationship of merocyanine dyes is of great importance for the development of ideal sensors with desirable performance. In this work, a series of coumarin/merocyanine (CMC) hybrid fluorescent probes with different lipophilicities have been developed. By altering the N-alkyl chain, the reaction rate with H2S and intracellular distribution of CMC sensors are optimized. The results showed that increasing the lipophilicity by attaching longer N-alkyl chains leads to a faster sensing response as well as a higher efficiency of the mitochondrial targeting ability. By virtue of rapid sensing of H2S and impressive mitochondrial co-localization ability, CM-NC6 could monitor H2S levels via a dual channel ratiometric mode. In addition, CM-NC6 is also capable of in vivo imaging of exogenous H2S. The work provided a powerful strategy for developing H2S sensors with optimized performance, which would be helpful for understanding the complicated roles of H2S in various physiological processes. [ABSTRACT FROM AUTHOR]

Naringin inhibits inflammation and oxidative stress, the P2 purinoreceptor X4 receptor (P2X4R) is associated with glial cell activation and inflammation, the purpose of this study is to investigate the effects of naringin on P2X4 receptor expression on satellite glial cells (SGCs) and its possible mechanisms. ATP promoted the SGC activation and upregulated P2X4R expression; naringin inhibited SGC activation, decreased expression of P2X4R, P38 MAPK/ERK, and NF-kB, and reduced levels of Ca2+, TNF-α, and IL-1p in SGCs in an ATP- containing environment. These findings suggest that naringin attenuates the ATP-induced SGC activation and reduces P2X4R expression via the Ca2+-P38 MAPK/ERK-NF-kB pathway. [ABSTRACT FROM AUTHOR]

Angiogenesis and metastasis are major factors affecting the growth and invasion of triple negative breast cancer (TNBC). A phenanthroline copper(II) complex CPT8 modified with an alkyl chain-linked triphenylphosphonium group showed potent antiproliferative activity against a series of cancer cells including TNBC MDA-MB-231 cells. CPT8 induced mitophagy through activation of PINK1/Parkin and BNIP3 pathways in cancer cells due to damage to mitochondria. More importantly, CPT8 reduced the tube formation ability of human umbilical vein endothelial cells (HUVEC) through downregulation of nuclear factor erythroid 2-related factor 2 (Nrf2). The anti-angiogenic potential of CPT8 was confirmed by decreased vascular endothelial growth factor (VEGF) and CD34 expression in HUVEC. Moreover, CPT8 suppressed the expression of vascular endothelial cadherin and matrix metalloproteinases MMP2 and MMP9, leading to the inhibition of vasculogenic mimicry formation. CPT8 also weakened the metastatic potential of MDA-MB-231 cells. Downregulation of Ki67 and CD34 expression indicates that CPT8 suppressed tumor proliferation and vascularization in vivo, thus providing a unique metal drug candidate for the treatment of TNBC. [ABSTRACT FROM AUTHOR]

Transient receptor potential vanillic acid 1 (TRPV1) is an ion channel activated by heat and inflammatory factors involved in the development of various types of pain. The P2X7 receptor is in the P2X family and is associated with pain mediated by satellite glial cells. There might be some connection between the P2X7 receptor and TRPV1 in neuropathic pain in diabetic rats. A type 2 diabetic neuropathic pain rat model was induced using high glucose and high-fat diet for 4 weeks and low-dose streptozocin (35 mg/kg) intraperitoneal injection to destroy islet B cells. Male Sprague Dawley rats were administrated by intrathecal injection of P2X7 shRNA and p38 inhibitor, and we recorded abnormal mechanical and thermal pain and nociceptive hyperalgesia. One week later, the dorsal root ganglia from the L4-L6 segment of the spinal cord were harvested for subsequent experiments. We measured pro-inflammatory cytokines, examined the relationship between TRPV1 on neurons and P2X7 receptor on satellite glial cells by measuring protein and transcription levels of P2X7 receptor and TRPV1, and measured protein expression in the PKCε/P38 MAPK/NF-κB signaling pathway after intrathecal injection. P2X7 shRNA and p38 inhibitor relieved hyperalgesia in diabetic neuropathic pain rats and modulated inflammatory factors in vivo. P2X7 shRNA and P38 inhibitors significantly reduced TRPV1 expression by downregulating the PKCε/P38 MAPK/NF-κB signaling pathway and inflammatory factors in dorsal root ganglia. Intrathecal injection of P2X7 shRNA alleviates nociceptive reactions in rats with diabetic neuropathic pain involving TRPV1 via PKCε/P38 MAPK/NF-κB signaling pathway. [ABSTRACT FROM AUTHOR]

The frictional stability of rocks is fundamental in controlling the instability and activation of faults. Given the strong correlation between seismic events in the Sichuan Basin of China and hydraulic fracturing for shale gas extraction, we conducted a series of velocity-stepping friction experiments with Longmaxi shale from the Changning shale gas extraction block under fluid injection. The experimental results indicate that the frictional process of Longmaxi shale can be divided into four distinct stages and the effective normal stress can demonstrate the influence of injection pressure. Additionally, the phenomenon of a decreasing friction coefficient μ with increasing effective normal stress can be explained by the frictional adhesion theory and a competitive mechanism between the deformation of asperities and microscopic dilatant slip. As the injection pressure increases, the friction state of Longmaxi shale transitions from velocity-strengthening to velocity-weakening, which is beneficial for potential seismic slip. After friction, the fracture surface experiences wear, and the surface morphology of the left and right parts exhibits a symmetrical distribution. With increasing effective normal stress, the morphological evolution of fractures becomes more prominent, which is related to the variation in the effective contact area. Based on the experimental results, we propose that the uneven distribution of fluid pressure on the Longmaxi shale fracture may also contribute to the transformation of frictional stability. When studying the frictional properties of rocks under fluid injection, it is also necessary to focus on the evolution of fluid pressure distribution on the fracture surface during the frictional process. • The frictional process of Longmaxi shale under fluid injection can be divided into four stages. • Pressurized fluid can accelerate the transition of Longmaxi shale from the V-strengthening state to the V-weakening state. • The morphological evolution of Longmaxi shale fracture is related to the variation in the effective contact area. • Uneven distribution of fluid pressure is also a presumable factor changing the frictional stability of Longmaxi shale. [ABSTRACT FROM AUTHOR]

Cisplatin is a widely used chemotherapeutic agent which interacts with DNA to form Pt-DNA adducts, leading to DNA double-strand breaks and apoptosis. Resistance is the major obstacle in the clinical application of cisplatin. A quinoline derivative based Pt(II) complex PtQ was synthesized and characterized. As an analogue of cisplatin, PtQ demonstrated a novel anticancer mechanism in ovarian cancer. PtQ caused excessive production of reactive oxygen species (ROS), which triggered ferroptotic cell death in ovarian cancer. Cystine/glutamate antiporter SLC7A11 and glutathione peroxidase 4 (GPX4) which alleviate lipid peroxidation were both downregulated in PtQ-treated SKOV3 cells. Furthermore, PtQ induced DNA single-strand breaks and suppressed the expression of single-strand breaks repair protein PARP1. Mechanism studies demonstrated that PtQ can hopefully bypass the signaling pathways mediated cisplatin resistance in ovarian cancer. As a CDDP-like Pt(II) complex, PtQ caused DNA single-strand breaks and suppressed the expression of repair protein PARP1. The tumor suppressor p53 was activated following PtQ-induced DNA damage and downregulated the expression of SLC7A11/GPX4 signal axis, which triggered ferroptosis in ovarian cancer. [Display omitted] • A quinoline derivative based Pt(II) complex PtQ with was designed and investigated. • PtQ triggered ferroptosis in ovarian cancer through downregulation of SLC7A11/GPX4. • PtQ caused DNA single-strand breaks and inhibited the expression of PARP1. [ABSTRACT FROM AUTHOR]

[Display omitted] The characteristics of structural fractures (faults) have a significant impact on the preservation, enrichment, and hydraulic fracturing of deep shale gas in complex structural zones. In this study, the development characteristics and controlling factors of structural fractures are analyzed using collected data, such as field outcrops, cores, thin sections, imaging logs, seismic interpretations, and production test data, etc. The distribution pattern of fractures is quantitatively predicted using geophysical properties. Shear fractures of structural origin predominate in the study area, displaying consistent and inheritable multiscale development characteristics. The presence of fractures is prominent in the Wufeng Formation and the 1st, 2nd, and 3rd layers of the 1st Submember of the Longmaxi Formation, with the 4th layer exhibiting the lowest fracture density. The development of fractures is primarily influenced by faults, folds, brittle minerals, total organic content (TOC), and other geological variables. The degree of fracture development displays an exponential relationship with the distance from faults. Variations in fracture development are observed in different structural positions, with the closed anticline area displaying the highest fracture development. High TOC and brittle mineral content are conducive to fracture development, with respective critical values of 2 % and 44 %. Employing the average density of typical drilling-induced fractures as a constraint, we have developed a quantitative multi-parameter regression-based fracture prediction model based on geological (core and imaging logging) and geophysical methods. The prediction results indicate that fracture density ranges from 0 to 3.5 m−1, and the distribution of fractures is jointly governed by structural positions and faults. Compared with the actual fracture density of the wells, the quantitative fracture prediction accuracy reaches approximately 90 %. [ABSTRACT FROM AUTHOR]

Ru(II) complexes have been recognized as excellent anticancer candidates. However, the poor cell uptake of these complexes has been the major obstacle in improving their anticancer efficacy. Along with the development of the knowledge on the anticancer nature of the Ru(II) complexes, several strategies have been designed to increase the cellular accumulation of these complexes. Among them, the light-triggered drug uptake approach is most promising. In this study, a bioactive Ru(II)–polypyridyl complex Ru-1 is constructed via incorporating a modified phenanthroline ligand into the enlarged conjugate structure. The modulation of the ligand makes Ru-1 powerful in generating singlet oxygen and effective in photodynamic therapeutic activity. Moreover, the cell uptake is improved during this photodynamic process and induces further chemotherapeutic effect, which act synergistically to enhance its anticancer activity. The photoinduced synergistic cytotoxicity of Ru-1 towards cancer cells offers an effective way to sensitize the antitumor activity of Ru(II) complexes. [ABSTRACT FROM AUTHOR]

Developing a ratiometric H2S fluorescent probe with fast response is of great importance for studying the H2S physiology. Herein, two hemicyanine-based H2S probes were constructed; the one with a propanoic acid group (CouPa) showed poor sensitivity while the other one with the N,N-diethylpropionamide moiety (CouDE) exhibited distinctly improved performance. CouDE showed the ability to detect mitochondrial H2S level fluctuation, which was triggered by alteration of CBS enzyme activity. Moreover, endogenous H2S change in solid tumours was monitored using CouDE. [ABSTRACT FROM AUTHOR]

The early detection of cancer shows great promise for the control and prevention of cancer. For early detection, one of the challenges that still exists is searching for methods that can illuminate tumors with high sensitivity. Here, acidity and hypoxia, two typical features that exist universally in a solid tumor microenvironment, were focused on to attain synergistic imaging with an enhanced signal-to-noise ratio. This was realized using an iridium(III) based optical probe (Ir-1) that could sense acidity and hypoxia simultaneously and synergistically. Through the synergistic sensing of acidic pH and hypoxia, stronger emission signals or larger lifetime changes can be obtained than if a single factor (acidity or hypoxia) is used to induce variations. Furthermore, its potential for biological applications was confirmed by employing Ir-1 for phosphorescence synergistic intensity and lifetime imaging of acidity and hypoxia in live monolayer cells and 3D multicellular spheroids. [ABSTRACT FROM AUTHOR]

Circumferential strain-control tests were suggested to obtain the complete stress–strain curves (SSCs) of intact rock. However, compression test performed by the axial strain-control loading is mostly used to obtain the strength parameters and the SSCs. The influences of load control modes on the mechanical behavior of rock have not been fully investigated and understood. In this study, triaxial compression tests are conducted on granite specimens loaded by using both axial strain-control and circumferential strain-control modes to examine influences of load control modes on the determined mechanical properties. The occurrence mechanism and influencing factors of class II behavior are studied, and the potential application of the class II SSC in the evaluation of brittle failure of hard rock is also discussed. Results show that the peak strength, elastic modulus and fracture angle are generally higher in the axial strain-control test than in the circumferential strain-control test, and the failure in the former is also more violent than the latter under the same confining pressure. The much lower and constant circumferential deformation rate applied in the circumferential strain-control test is the dominant factor that favors the recovery of the complete post-peak SSC. The lower measured values of strength and elastic modulus are also associated with the lower deformation rate in the circumferential strain-control test, with a higher degree of damage and cohesion weakening occurring inside the rock. The development of the class II SSC is attributed to the axial strain recovery during the release of the stored elastic energy, which is influenced by the ratio of elastic energy to dissipated energy in the pre-peak stage, and is also associated with the consumed energy with respect to plastic deformation or initiation and propagation of new cracks in the post-peak stage. The class II SSC can aid the differentiation of the energy accumulation and consumption of different brittle rocks, which are usually characterized by a more abrupt and larger stress drop in the axial strain-control test. It can then be used to evaluate the strain rockburst potential of a particular rock type. [ABSTRACT FROM AUTHOR]

Tensile stress is a ubiquitous concern in rock engineering, and it is still a challenging task to determine reasonably the tensile strength of rock materials. The main shortcomings of existing direct tensile testing methods include high requirements for test equipment, complex preparation processes, and high proneness of test failure. For the bonding or clamping method, it is not only difficult to ensure the alignment of tensile stress to the specimen axis, but also easy to break the sample in the bonding or clamping segment. To overcome the shortcomings of the existing methods, a novel direct testing method for tensile strength is examined in this study. This method allows determination of rock tensile strength via conventional rock mechanics testing systems and the test results exhibit good consistency, which has incomparable advantages compared with traditional testing methods. [ABSTRACT FROM AUTHOR]

A molecular modified polyacrylamide with Gemini surfactant monomers, named as HA1, was evaluated in this paper as an alternative to enhance the offshore heavy oil recovery. The physical properties of HA1 solution including apparent viscosity, rheological properties, static adsorption, interfacial activities (IFT, interfacial visco-elasticity and contact angle), emulsification ability, as well as oil recovery capacity were comprehensively investigated. Our results indicate that due to the hydrophobic and Gemini surfactant monomers on the acrylamide backbone, this novel amphiphilic polymer possesses more advanced functions than conventional polymers. HA1 demonstrates pronounced aqueous-phase viscosifying ability by forming 3D network in solution when the concentration is above CAC. In addition, the IFT, interfacial visco-elasticity and contact angle response illustrate that HA1 interacts strongly with the oil-phase which gives rise to its significant interfacial activity. Thereby, HA1 is able to reduce the heavy oil viscosity by emulsifying oil into water phase even at relatively low water content (20%) and also avoids dehydration difficulty by reducing the oil-brine interfacial rigidity. Furthermore, the asphaltene morphology change due to HA1 observed by SEM and AFM proves that HA1 can disperse the asphaltene aggregates in the crude oil, leading to a direct reduction of the heavy oil viscosity. At last, the coreflooding in an artificially synthesized triple-layered porous media shows that HA1 gives rise to an additional oil recovery of 27.04%, at the optimum concentration of 1600 ppm, by improving sweep efficiency, microscopic efficiency and dispersion of the asphaltene aggregates. Therefore, the potential of HA1 to enhance heavy oil recovery is comparable to traditional multi-component polymer-surfactant flooding. Since HA1 is single-component, it can also mitigate incompatibility issues like chromatography separation and surfactant-polymer interactions. Overall, this new self-assembly system shows potential for applications in heavy oil recovery. • The novel amphiphilic polymer possesses pronounced viscosifying ability by forming 3D network when above CAC. • HA1 interacts strongly with the oil-phase which gives rise to its significant interfacial activity. • HA1 reduces the heavy oil viscosity by emulsification even at low water content and avoids dehydration difficulty. • HA1 can disperse the asphaltene aggregates, thereby leading to a viscosity decrease. [ABSTRACT FROM AUTHOR]

The resistivity anisotropy of shale has a non-negligible effect on resistivity logs. Many studies have shown that the macroscale factors of shale anisotropy are depositional environment, compaction process, and diagenesis process, and the microscale factors mainly include lamination, orientation of clay minerals, and microfractures. However, the mechanism of laminations, pores, organic matters, pyrite and clay minerals driving resistivity anisotropy remains unclear. In this research, experiments and simulations were performed to investigate the characteristics and mechanism of the resistivity anisotropy of shale. Two sets of shale samples were collected at different inclination angles from the Lower Silurian Longmaxi Formation in the Pengshui area, southeastern Sichuan Basin, China. Core sample resistivities were measured in several water saturation states established using imbibition, pressurized saturation and centrifuge methods. Scanning electron microscopy, thin sections, X-ray diffraction, the mercury injection capillary method, and N 2 adsorption were also performed. Resistivity simulations were applied to three-dimensional models derived from the microimages. The results of the experiments and simulations show that Longmaxi shale has strong resistivity anisotropy. The resistivity anisotropy coefficient (λ) of Longmaxi shale ranged from 1.3699 to 2.1623. Longmaxi shale has a strong lamination structure. In the submillimeter scale, strawberry-like pyrite (3.8%–10.2%, v /v) aggregates in elongated strips with an extension direction consistent with the horizontal direction. Due to the differential compaction, the clay minerals (21.1%–26.4%, v /v) also tend to be parallel to the formation bedding. The most obvious directional distribution of pores occured in the organic pores. Most interparticle pores between detrital minerals did not exhibit anisotropic characteristics. Because of the horizontal distribution of lamination, pyrite, clay minerals and organic pores, a higher resistivity is measured in the vertical direction than in the horizontal direction. • Lamination, distribution of minerals and pores affect shale resistivity anisotropy. • Large quartz and feldspar grains in laminae block vertical flow of electricity. • Accumulation of strawberry-like pyrite decreases horizontal resistivity of shale. • Organic pore exhibits more horizontal distribution characteristics than other pores. [ABSTRACT FROM AUTHOR]

The effects of the wor king angle on pneumatic down-the-hole (DTH) hammer drilling was investigated since these hammers were developed for vertical drilling and their performances in inclined positions need to be tested. The investigation begins by establishing a calculation model with which to simulate the percussive drilling of the hammer. The model consists of two parts. The first gives the kinetic energy of the piston at impact by simulating the thermodynamic cycle of the DTH hammer, and the second simulates the percussive drilling process according to the analyses of stress-wave propagation. In the meantime, a laboratory-scale test device was made for multi-angle hammer drilling tests. This device is based on a small pneumatic DTH hammer used in deep well drilling. By analyzing the force acting on the rock during impact at different angles, the percussive drilling process is carefully examined. Theoretical predictions and experimental results appear in fairly good agreement. The hammer's working performance in inclined positions can be obtained directly using the proposed model. Furthermore, when detailed evaluation is required, the hammer can be tested using the method proposed in this paper. [ABSTRACT FROM AUTHOR]

Liquid loading is one of the main factors that can severely impede shale gas production. It is crucial for efficient operation of gas production to forecast the liquid loading in real time. Most of the existing techniques for liquid loading prediction are based on physical modeling, which are generally limited by human knowledge of the underlying mechanism of liquid loading formation. In this study, we propose a data-driven method for liquid loading prediction in shale gas wells based on deep anomaly detection technology. In particular, we employ deep neural networks to learn the normal behavior of a well and test a given sequence for anomaly by measuring the sequence reconstruction errors of the neural network with adaptive threshold. Unlike existing physical model-based methods, our method makes no assumptions about the cause of liquid loading, while the prediction results are merely determined by historical records. To verify the effectiveness of our method, we conduct experiments on real shale gas production data coming from 73 shale gas wells and the precision of method is 85.71%. The experimental results demonstrate that our method surpasses existing physical modeling based methods at prediction accuracy and timeliness. • A data-driven method for the liquid loading prediction in shale gas wells is proposed. • Fine-grained real-time production data are used in liquid loading prediction for the first time. • The proposed data-driven method shows superior predictive performance. [ABSTRACT FROM AUTHOR]

Limestone caprock permeability and damage characteristics have a significant impact on the tightness and stability of salt cavern gas storage. To investigate the gas sealing capacity of limestone as caprock for a gas reservoir at different burial depths, triaxial compression coupled with permeability tests of limestone subjected to different confining pressures and temperatures were carried out using the improved MTS 815 test machine. After the tests, X-ray micro-computed tomography (μCT) is used to perform CT scanning of the limestone sample after seepage failure to estimate the rock meso-damage. The experimental results depicted that: (1) At the confining pressures of 10 MPa, 20 MPa and 30 MPa, the final permeability increases with the increase of temperature, while at the confining pressures of 40 MPa, the evolution of the final permeability is opposite. (2) The pore radius of limestone is concentrated in the range of 0–200 μm, and the pore with a radius greater than 1200 μm is the main permeability channel with the greatest contribution. The final permeability is positively correlated with porosity. (3) The fractal dimension decreases with the increase of confining pressure, and some areas of rock do not have fractal characteristics when the confining pressure reaches 40 MPa. Permeability after rock damage is positively correlated with the fractal dimension and the maximum pore diameter and negatively correlated with the tortuous fractal dimension, according to the fractal permeability model. These experimental results and analyses provide scholars and engineers with a thorough understanding of cap rock tightness in the construction of deep-earth gas storage reservoirs. • The permeability evolution of limestone rock under THM coupling was investigated. • The meso-damagee characteristics base on CT was obtained. • The effectiveness of the fractal permeability model is verified. [ABSTRACT FROM AUTHOR]

To capture the 3D morphological features of drying soils, we explore the potential of using a structured light scanner. Bentonite clay is used for desiccation tests. Both 2D images and 3D scans are obtained at certain time intervals throughout the test. We develop a post-processing methodology to quantify the 2D and 3D features of soil cracking, including surface crack ratio, total volume, surface area, and fractal dimension. Experimental results validate that the structured light scanner enables 3D high-resolution and accurate scanning of the soil desiccation cracking patterns. The change of 3D soil volume is more influenced by the widening of desiccation cracks, with slower soil volume reduction corresponding to the moment when primary cracks propagate vertically downwards. The spatiotemporal evolution of 3D reconstructed model indicates that the soil surface shrinks first, more in the central region and less along the boundaries due to the boundary constraint, before crack initiates and propagates. Both surface area and fractal dimension increase monotonically before the evaporation stops, with both more susceptible to the change of crack depth rather than crack width. Through presenting a new approach for soil desiccation cracking analysis, this study is expected to provide new insights into the soil desiccation process. • Structured light scan captures 3D soil morphological and crack pattern changes. • Crack propagates downward from soil surface and grows wider under drying. • Surface area and fractal dimension of soil increases with lower water content. [ABSTRACT FROM AUTHOR]

Natural soiling of photovoltaic (PV) panel is an increasing problem especially in arid and desert areas. Finding a strategy that can reduce dust adhesion on PV panels is highly desirable but remains challenging. In this paper, different wettability of transparent coatings including superhydrophilic, hydrophilic, hydrophobic and superhydrophobic coatings were prepared to investigate the importance of surface roughness and surface energy. Their anti-soiling effects were investigated under different airflow velocity and different tilt angles. Dust deposition density, reduced transmittance, the ratio of reduced transmittance between bare glass surfaces and coatings, and PV efficiency reduction were used to characterize dust resistance performances. It is found that dust adhesion on superhydrophilic coatings was eminently governed by their respective high surface energy, with surface roughness rendering lesser contribution towards resisting/adhering effects. However, for other three coatings, further reducing the surface energy had little influence on the improvement of dust-proof ability. A large airflow velocity is beneficial to resist dust adhesion for all four types of coatings. However, a large airflow velocity has a limited ability to improve the anti-soiling effect of superhydrophilic coating under different tilt angles compared with other three coatings. The anti-soiling coatings can be referred to hydrophilic and hydrophobic coatings, not limited to superhydrophobic coating only. The study provides an invaluable guiding significance for preparation of dust-resistant coatings. • The anti-soiling effects of different wettability of transparent coatings were investigated. • The anti-soiling effects were investigated under different airflow velocity and tilt angle. • Large airflow velocity was beneficial to resist dust adhesion for all four types of coatings. • The anti-soiling effect of superhydrophilic coating was the weakest under different tilt angles. • Surface roughness and surface energy both rendered contribution towards anti-soiling. [ABSTRACT FROM AUTHOR]