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Blocked fallopian tubes, leading to tubal factor infertility, seriously affect fertility and pregnancy. The current mainstream surgical approach for tubal recanalization is based on conventional catheters and guidewires to clear the blockage. However, it is challenging to treat the distal tubal obstruction due to the large size of the tubal catheter and the poor steerability of the guidewire. Here, we present a magnetically driven robotic microscrew to clear blocked fallopian tubes based on a helical rotating mode. The microscale screw-shaped microrobot is fabricated by 3D microfabrication technology. The motion direction and speed of the microrobot are modulated by customizing the pattern and parameters of the control magnetic field. The microscrew structure generates mechanical force to drill the blockage, and then the destroyed fragments are transported to the tail of the robots via the vortex flow surrounding the microscrew. Finally, we demonstrate the recanalization effect of the proposed microrobot in the fallopian tube-mimicking phantom. The recanalizing microscrew represents a potential strategy for developing autonomous tools to treat the blockage of small lumens.

A finite element model, which includes reservoir rock, cement stone, casing, and perforation channels, was developed. The purpose of the study is to create a geomechanical model of the zone around the well, which includes support elements and perforation channels. This model will help predict changes in the productivity coefficient of a terrigenous reservoir and determine the most efficient mode of operation of a producing well. In order to exclude the stress concentration within the casing–cement stone and cement stone–rock, the numerical model applies contact elements. As a result, structural elements slip, while the stresses are redistributed accurately. The numerical simulation of a stress state in the near-well zone was carried out by using the developed model with differential pressure drawdown on the terrigenous reservoir, one of the oil fields in the Perm region. It is shown that the safety factor of the casing reaches roughly 3–4 units. The only exceptions are the upper and lower parts of the perforations, where this parameter is close to one unit. The safety factor of cement stone accounts for 2–3 units. However, parts with its lowest value (1.35) are also concentrated near the perforation channels. In order to analyze the change in permeability, the dependence of the safety factor on effective stresses was taken into account. Therefore, it was found that, in the upper and lower parts of perforations, the stresses decreased, while permeability rose by up to 20% of the initial value. An increase in differential pressure drawdown, on the contrary, can lead to a permeability reduction of 25%, especially in the lateral parts of the perforations. Areas of rock destruction under tensile and compressive forces were identified by using the Mohr–Coulomb criterion. It is estimated that with an increase in pressure drawdown, the areas of rock destruction under tensile force disappear, while the areas of rock destruction under compression increase. After further analysis, it was found that, with the maximum pressure drawdown of 12 MPa, the well productivity index can decrease by 15% due to the reservoir rock compaction.

Groundwater pollution poses a significant threat to ecosystems and public safety. Traditional remediation methods have limitations, necessitating innovative approaches. This study integrates numerical modeling and bioremediation to address groundwater contamination in an industrial site. It explores the potential of chemotactic bacteria to enhance remediation efficiency. The research establishes groundwater pollutant transport models, analyzes flow fields, and assesses the distribution of various pollutants. The results demonstrate the effectiveness of chemotactic bacteria, particularly chemotactic bacteria that can rapidly adapt as the pollutant concentration decreases, the concentration of chemotactic bacteria in the low-permeability area has increased by 112%. This study provides insights into the practical application of bioremediation and the promising role of bacterial chemotaxis in treating contaminated groundwater.

Abstract Background Although recent guidelines advocate for HbA1c target individualization, a comprehensive criterion for patient categorization remains absent. This study aimed to categorize HbA1c variability levels and explore the relationship between glycemic control, cardiovascular outcomes, and mortality across different degrees of variability. Methods Action to Control Cardiovascular Risk in Diabetes study data were used. HbA1c variability was measured using the HbA1c variability score (HVS) and standard deviation (SD). K-means and K-medians clustering were used to combine the HVS and SD. Results K-means clustering was the most stable algorithm with the lowest clustering similarities. In the low variability group, intensive glucose-lowering treatment significantly reduced the risk of adverse cardiovascular outcomes (HR: 0·78 [95% CI: 0·63, 0·97]) without increasing mortality risk (HR: 1·07 [0.81, 1·42]); the risk of adverse cardiovascular events (HR: 1·33 [1·14, 1·56]) and all-cause mortality (HR: 1·23 [1·01,1·51]) increased with increasing mean HbA1c. In the high variability group, treatment increased the risk of cardiovascular events (HR: 2.00 [1·54, 2·60]) and mortality (HR: 2·20 [1·66, 2·92]); a higher mean HbA1c (7·86%, [7·66%, 8·06%]) had the lowest mortality risk, when the mean HbA1c was

The last decade has seen a surge of interest in the field of catalytically propelled micro‐ and nanoswimmers for their potential use in biomedical applications, such as biosensing, biopsy, targeted drug delivery, and on‐the‐fly chemistry. However, to fully utilize these devices, precise control over their motion is essential. Therefore, it is important to thoroughly understand their locomotion mechanisms. Herein, the currently accepted mechanisms for propulsion are discussed, which are self‐electrophoresis, self‐diffusiophoresis, and bubble recoil. Additionally, the concept of using multilocomotive mechanisms as a solution to achieve fully autonomous navigation is explored. Moreover, recent advances in the design of these devices are explored.

Microrobots have shown great potential in many applications, such as non‐invasive surgery, tissue engineering, precision medicine, and environmental remediation. Within the past decade, soft microrobot has become one of the important branches. It is aimed to create soft and deformable microrobots with high bioaffinity, which can perform complex tasks noninvasively in inaccessible small spaces in the body. Herein, the latest research progress of soft microrobots regarding the three cornerstones of this field is reviewed: material, fabrication, and actuation. First, various materials that are used for the fabrication of soft microrobots are summarized, and their characteristics and functions are discussed. Second, various fabrication methods of soft microrobots are introduced, and their applicability to different materials is discussed. Third, the actuation methods of soft microrobots are discussed, as well as their pros, cons, and adaptability. Moreover, the outstanding behaviors of soft microrobots in biomedical and environmental applications are introduced with some typical examples published recently. Finally, current clinical use challenges of soft microrobots are pointed out, and their intelligentization is proposed and discussed for further innovative development.

Background: The purpose of this study was to evaluate the impact of glucose levels on admission, on the risk of 30-day major adverse cardiovascular events (MACEs) in patients with acute myocardial infarction (AMI), and to assess the difference in outcome between ST-segment elevation myocardial infarction (STEMI) and non-ST-segment elevation myocardial infarction (NSTEMI) patients. Methods: This study was a post hoc analysis of the Acute Coronary Syndrome Quality Improvement in Kerala Study, and 13,398 participants were included in the final analysis. Logistic regression models were used to assess the association between glucose levels on admission and the risk of 30-day MACEs, adjusting for potential confounders. Results: Participants were divided according to the glucose quintiles. There was a positive linear association between glucose levels at admission and the risk of 30-day MACEs in AMI patients [adjusted OR (95% CI): 1.05 (1.03, 1.07), p < 0.001]. Compared to participants with an admission glucose between 5.4 and 6.3 mmol/L, participants with the highest quintile of glucose level (≥10.7 mmol/L) were associated with increased risk of 30-day MACEs in the fully adjusted logistic regression model [adjusted OR (95% CI): 1.82 (1.33, 2.50), p < 0.001]. This trend was more significant in patients with STEMI (p for interaction = 0.036). Conclusions: In patients with AMI, elevated glucose on admission was associated with an increased risk of 30-day MACEs, but only in patients with STEMI.

Over the past decade, soft robot research has expanded to diverse fields, including biomedicine, bionics, service robots, human–robot interaction, and artificial intelligence. Much work has been done in modeling the kinematics and dynamics of soft robots, but closed‐loop control is still in its early stages due to limited sensory feedback. Thanks to the advancement in functional materials, structures, and manufacturing techniques for flexible electronics, flexible and stretchable sensors are developing rapidly. These sensors provide feedback for closed‐loop control tasks and enable soft robots to effectively explore the unknown and safely interact with humans and the environment. Herein, recent advances in perceptive soft robots that utilize flexible/stretchable sensors and functional materials are outlined. The perceptive functions of soft robots from two different aspects, that is, proprioception and exteroception, are summarized. Furthermore, the constructions of autonomous soft robots by integrating both proprioceptive and exteroceptive capabilities for closed‐loop control tasks and other challenging tasks in the real world are discussed.

Background Frailty and cognitive impairment are common in the elderly, with various shared risk factors like hypertension. Frailty is a marker for future cognitive function. Moreover, whether intensive blood pressure interacted with frailty and cognitive impairment is unknown. Methods and Results We performed a post hoc analysis of data from SPRINT (Systolic Blood Pressure Intervention Trial). The relationship between frailty and a composite of probable dementia (PD) and mild cognitive impairment (MCI) was analyzed. Also, we evaluated the interaction of intensive blood pressure lowering in the relationship between frailty and cognitive impairment. A total of 8537 patients were included in our study, and 35.1% were women. The mean age of these participants was 67.9±9.3 years. According to the baseline frailty index, 1670, 4637, and 2230 patients were in fit, less fit, and frail statuses, respectively. During a mean follow‐up of 4.61 years, 871 cases of PD or MCI occurred. Compared with those in fit status, those with less fit (hazard ratio [HR], 2.14 [95% CI, 1.65–2.77]) and frailty (HR, 4.28 [95% CI, 3.26–5.61]) status had a higher incidence of a composite of PD and MCI. Blood pressure control strategy interacted with the correlation between frailty and cognitive impairment. Intensive blood pressure control (HR, 2.4 [95% CI, 2.0–2.8]) accelerated the relationship between frailty and incidence of PD and MCI compared with the standard treatment group (HR, 1.8 [95% CI, 1.5–2.1]; P for interaction=0.009). Conclusions This study found that the baseline frailty status was a possible marker for the incidence of a composite of PD and MCI. Intensive blood pressure control may strengthen this correlation. Registration URL: https://clinicaltrials.gov/; Unique identifier: NCT01206062.

Abstract Background Myocardial fibrosis after myocardial infarction (MI) is one of the leading causes of cardiovascular diseases. Cardiac fibroblasts (CFs) are activated and promoted by MI to undergo myofibroblast transformation (CMT). Urolithin A (UA) is an active and effective gut metabolite derived from polyphenolics of berries and pomegranate fruits, which has been reported to have anti-inflammatory and anti-oxidant functions. However, whether UA affects the CMT process during myocardial fibrosis remains unclear. Methods TGF-β1-treated primary rat cardiac fibroblasts were used for in vitro study. Cell proliferation ability was evaluated by MTT assay. Cell migration and invasion abilities were tested by wound healing and Transwell assays. The expression of CMT process-related markers were measured by qRT-PCR and western blot. The rat MI model was established by left anterior descending coronary artery (LAD) ligation and evaluated by H&E and Masson staining. Results Our data demonstrated that UA treatment could inhibit the CMT process in TGF-β1-induced CFs, including cell proliferation, migration and invasion abilities. Knocking down of Nrf2, which was activated by UA treatment, could mitigate the effects of UA treatment on CMT process. Moreover, in vivo administration of UA in rat MI model successfully up-regulated Nrf2 expression and improved the myocardial damage and fibrosis. Conclusions The study discovered the function and mechanism of UA on myocardial fibrosis and demonstrated the protective effects of UA administration through activation of Nrf2 pathway.

Untethered microrobots can be used for cargo delivery (e.g., drug molecules, stem cells, and genes) targeting designated areas. However, it is not enough to just reach the lesion site, as some drugs can only play the best therapeutic effect within the cells. To this end, folic acid (FA) was introduced into microrobots in this work as a key to mediate endocytosis of drugs into cells. The microrobots here were fabricated with biodegradable gelatin methacryloyl (GelMA) and modified with magnetic metal–organic framework (MOF). The porous structure of MOF and the hydrogel network of polymerized GelMA were used for the loading of enough FA and anticancer drug doxorubicin (DOX) respectively. Utilizing the magnetic property of magnetic MOF, these microrobots can gather around the lesion site with the navigation of magnetic fields. The combination effects of FA targeting and magnetic navigation substantially improve the anticancer efficiency of these microrobots. The result shows that the cancer cells inhibition rate of microrobots with FA can be up to 93%, while that of the ones without FA was only 78%. The introduction of FA is a useful method to improve the drug transportation ability of microrobots, providing a meaningful reference for further research.

Abstract Aims This meta‐analysis aimed to determine whether coronary artery bypass grafting (CABG) or percutaneous coronary intervention (PCI) should be preferred in patients with severely reduced left ventricular (LV) ejection fraction. Methods and results We searched the PubMed, EMBASE, and Cochrane Library databases from the conception of the databases till 1 May 2020 for studies on patients with severely reduced LV ejection fraction undergoing CABG and PCI. The primary clinical endpoints were 30 day and long‐term mortalities. The secondary endpoints were 30 day and long‐term incidences of myocardial infarction (MI) and stroke, long‐term cardiovascular mortality, and repeat revascularization. Eighteen studies involving 11 686 patients were analysed. Compared with PCI, CABG had lower long‐term mortality [hazard ratio (HR): 0.70, 95% confidence interval (CI): 0.61–0.80, P

Abstract Background Although studies have shown that waist circumference (WC) is positively associated with an increased risk of cardiovascular diseases among the normal population, few studies have investigated WC in patients with type-2 diabetes mellitus (T2DM). Methods This was a post hoc analysis of the Action to Control Cardiovascular Risk in Diabetes (ACCORD) study. The Cox proportional hazards models was used to investigate the relationship between WC and major adverse cardiovascular events (MACEs) in T2DM patients with cardiovascular disease (CVD) or high risk factors of CVD. Results A total of 10,251 T2DM patients (6299 men [61.4%], 3952 women [38.6%]) were included in our analysis. The mean age was 64.0 ± 7.53 years. After a mean follow-up at 9.2 ± 2.4 years later, 1804 patients (event rate of 23 per 1000 person-years) had developed MACEs. MACEs rates in men and women were 18.0 and 26.0 events per 1000 person-years, respectively. After multivariable adjustment, each increase in WC of 1 SD increased the risk of MACEs (HR: 1.10, 95% CI 1.04–1.17; P

Objective: Patients with well-developed coronary collateral circulation (CC) usually have low mortality, improved cardiac function, and reduced infarct size. Currently, there is conflicting evidence on the association between traditional cardiovascular risk factors (diabetes, hypertension, and smoking habit) and CC.Design: We performed a meta-analysis of case-control studies to better understand such associations.Data Sources: We searched the MEDINE, EMBASE, and Science Citation Index databases to identify relevant studies.Eligibility Criteria for Selecting Studies: Case control studies reporting data on risk factors (smoking habit, hypertension, and diabetes mellites) in comparing cases between poor CC and well-developed CC groups. Well-developed CC was the primary outcome of this meta-analysisData Extraction and Synthesis: Relevant data were extracted by two independent investigators. We derived pooled odds ratios (ORs) with random effects models. We performed quality assessments, publication bias, and sensitivity analysis to ensure the reliability of our results.Results: In total, 18 studies that had 4,746 enrolled patients were analyzed. Our results showed that hypertension and smoking habit did not (OR = 0.94, 95% CI: 0.75–1.17, p = 0.564 and OR = 1.00, 95% CI: 0.84–1.18, p = 0.970, respectively), and diabetes did (OR = 0.50, 95% CI: 0.38–0.67, p = 0.00001) affect the development of CC.Conclusion: Unlike hypertension and smoking habit, diabetes was associated with poor CC formation.Trial Registration Number:https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=87821, identifier: CRD42018087821.

Hydrogels are stretchable ion conductors that can be used as strain sensors by transmitting strain-dependent electrical signals. However, hydrogels are susceptible to dehydration in the air, leading to a loss of flexibility and functions. Here, a simple and general strategy for encapsulating hydrogel with hydrophobic elastomer is proposed to realize excellent water-retention capacity. Elastomers, such as polydimethylsiloxanes (PDMS), whose hydrophobicity and dense crosslinking network can act as a barrier against water evaporation (lost 4.6 wt.% ± 0.57 in 24 h, 28 °C, and ≈30% humidity). To achieve strong adhesion between the hydrogel and elastomer, a porous structured thermoplastic polyurethane (TPU) is used at the hydrogel-elastomer interface to interlock the hydrogel and bond the elastomer simultaneously (the maximum interfacial toughness is over 1200 J/m2). In addition, a PDMS encapsulated ionic hydrogel strain sensor is proposed, demonstrating an excellent water-retention ability, superior mechanical performance, highly linear sensitivity (gauge factor = 2.21, at 100% strain), and robust interface. Various human motions were monitored, proving the effectiveness and practicability of the hydrogel-elastomer hybrid.

Background: Women had worse outcomes after acute myocardial infarction (AMI), and physiologically, women had lower hemoglobin values. We examined whether there were sex-related differences in the relationship between hemoglobin levels and adverse outcomes in patients with acute myocardial infarction.Method: We conducted a post-hoc analysis of data from the Acute Coronary Syndrome Quality Improvement in Kerala (ACS-QUIK) Study. We explored the relationship between baseline hemoglobin level and 30-days adverse outcomes by logistic regression model, generalized additive model (GAM) and two-piecewise linear regression model. We used multiple imputation, based on five replications and a chained equation approach method in the R multiple imputation procedure, to account for missing data. The primary outcome were 30-day major adverse cardiovascular events (MACEs) defined as death, reinfarction, stroke, and major bleeding. The secondary outcomes were 30-day major bleeding, 30-day stroke and 30-day cardiovascular death (CVD death).Results: Twenty thousand, five hundred fifty-nine patients with AMI were included in our analysis. Baseline hemoglobin level was associated with major bleeding [OR: 0.74, 95%CI (0.60, 0.92) P < 0.01], CVD death [OR: 0.94, 95%CI (0.90, 0.99) P < 0.01], and MACEs [OR: 0.95, 95%CI (0.92, 0.99) P < 0.01]. There was no significant relationship between baseline hemoglobin level and stroke incidence in both men [OR: 1.02, 95%CI (0.90, 1.14) P = 0.77] and women [OR: 1.15, 95%CI (0.96, 1.37) P = 0.18]. Baseline hemoglobin level was associated with major bleeding [OR: 0.71, 95%CI (0.58, 0.85) P < 0.01] in male patients, however we did not find the same relationship in female patients [OR: 0.89, 95%CI (0.56, 1.41) P = 0.61]. GAM and two-piecewise linear regression model showed the relationships of hemoglobin level with major bleeding, CVD death, and MACEs were non-linear (non-linear P < 0.05), and the threshold value were 13, 14.8, and 14.3 g/dL for MACEs and CVD death, respectively.Conclusion: Baseline hemoglobin level was one of the independent predictors of prognosis in South Asia patients with acute myocardial infarction. Moreover, its impact on prognosis was largely different depending on the patients' sex.

The U.S. Environmental Protection Agency’s (EPA) Superfund—the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) database—has collected and built an open-source database based on nearly 2000 US soil remediation cases since 1980, providing detailed information and references for researchers worldwide to carry out remediation work. However, the cases were relatively independent to each other, so the whole database lacks systematicness and instructiveness to some extent. In this study, the basic features of all 144 soil remediation projects in four major oil-producing states (California, Texas, Oklahoma and Alaska) were extracted from the CERCLA database and the correlations among the pollutant species, pollutant site characteristics and selection of remediation methods were analyzed using traditional and machine learning techniques. The Decision Tree Classifier was selected as the machine learning model. The results showed that the growth of new contaminated sites has slowed down in recent years; physical remediation was the most commonly used method, and the probability of its application is more than 80%. The presence of benzene, toluene, ethylbenzene and xylene (BTEX) substances and the geographical location of the site were the two most influential factors in the choice of remediation method for a specific site; the maximum weights of these two features reaches 0.304 and 0.288.

Natural gas hydrates (NGHs) are regarded as a new energy resource with great potential and wide application prospects due to their tremendous reserves and low CO2 emission. Permeability, which governs the fluid flow and transport through hydrate-bearing sediments (HBSs), directly affects the fluid production from hydrate deposits. Therefore, permeability models play a significant role in the prediction and optimization of gas production from NGH reservoirs via numerical simulators. To quantitatively analyze and predict the long-term gas production performance of hydrate deposits under distinct hydrate phase behavior and saturation, it is essential to well-establish the permeability model, which can accurately capture the characteristics of permeability change during production. Recently, a wide variety of permeability models for single-phase fluid flowing sediment have been established. They typically consider the influences of hydrate saturation, hydrate pore habits, sediment pore structure, and other related factors on the hydraulic properties of hydrate sediments. However, the choice of permeability prediction models leads to substantially different predictions of gas production in numerical modeling. In this work, the most available and widely used permeability models proposed by researchers worldwide were firstly reviewed in detail. We divide them into four categories, namely the classical permeability models, reservoir simulator used models, modified permeability models, and novel permeability models, based on their theoretical basis and derivation method. In addition, the advantages and limitations of each model were discussed with suggestions provided. Finally, the challenges existing in the current research were discussed and the potential future investigation directions were proposed. This review can provide insightful guidance for understanding the modeling of fluid flow in HBSs and can be useful for developing more advanced models for accurately predicting the permeability change during hydrate resources exploitation.

Oil pollution in soil-groundwater systems is difficult to remove, and a large amount of residual oil is trapped in the low permeable layer of the heterogeneous aquifer. Aromatic hydrocarbons in oil have high toxicity and low solubility in water, which are harmful to the ecological environment. Chemotactic degrading bacteria can perceive the concentration gradient of non-aqueous phase liquid (NAPL) pollutants in the groundwater environment, and enrich and proliferate around the pollutants, thus achieving a more efficient and thorough remediation effect. However, the existing theoretical models are relatively simple. The physical fields of oil–water two-phase flow and oil-phase solute convection and diffusion in water are not coupled, which further restricts the accuracy of studies on bacterial chemotaxis to NAPL. In this study, geometric models based on the actual microfluidic experimental study were constructed. Based on the phase field model, diffusion convection equation and chemotaxis velocity equation, the effects of heterogeneity of porous media, wall wettability and groundwater flow rate on the residual oil and the concentration distribution of chemotaxis bacteria were studied. Under all of the simulation conditions, the residual oil in the high permeable area was significantly lower than that in the low permeable area, and the wall hydrophilicity enhanced the water flooding effect. Chemotactic bacteria could react to the concentration gradient of pollutants dissolved into water in the oil phase, and enrich near the oil–water interface with high concentration of NAPL, and the density of chemotactic bacteria at the oil–water interface can be up to 1.8–2 times higher than that in the water phase at flow rates from 1.13 to 6.78 m/d.

BackgroundSeveral studies have previously demonstrated that higher systolic blood pressure level means lower risk of adverse cardiovascular outcomes. However, there is a lack of further investigation into the nonlinear relationship between admission systolic blood pressure (SBP) and adverse outcomes of acute myocardial infarction (AMI) patients.ObjectivesThe aim of this study was to investigate the specific relationship between admission SBP and incidence of major adverse cardiovascular events (MACE) in 30 days for AMI patients.Methods and resultsUsing data from the ACS-QUIK trial, we analyzed 21,364 patients from Kerala, India. In univariate linear-regression model, the OR was 0.90 per 10mmHg, the confidence interval (CI) was 95% (0.87-0.92) and P < 0.0001. The generalized additive model (GAM) showed a nearly U-shaped curve between admission SBP and MACE. Using a two-piecewise linear regression model, we calculated an inflection point of 159 mmHg. We found that the higher admission SBP is associated with lower incidence of MACE of AMI patients. In addition, subgroups with different LVEF have distinct effects on blood pressure-related outcomes. Lower SBP has a greater risk when LVEF < 40%.ConclusionThe present study revealed the U-shaped relationship between admission SBP and the risk of adverse cardiovascular outcome. The admission SBP could be a marker to provide clinical assessment and treatment.Trial registrationURL: http://www.clinicaltrials.gov. Unique identifier: NCT02256657.

Takotsubo syndrome (TTS), also known as stress cardiomyopathy, is a type of acute heart failure syndrome triggered by intense psychological or physiological stress. TTS typically manifests as acute chest pain, dyspnea or syncope that mimics an acute myocardial infarction but does not involve coronary artery obstruction. The current understanding of the pathogenesis of TTS suggests that sympathetic nervous system (SNS) activation plays a central role. Specifically, stress can activate the SNS and lead to the over-release of catecholamine, which have toxic effects on myocardial tissue when present at excessive levels. However, the brain changes associated with TTS and the connection between the brain and the heart in patients with this disease remain unclear. In recent years, several published reports have revealed the role of this brain-heart connection in the pathogenesis of TTS. This review summarizes recent studies regarding SNS activation, catecholamine overload, and the brain-heart connection in patients with TTS from both pathophysiological and mechanistic aspects.

CO2 enhanced shale gas recovery (CO2-ESGR) draws worldwide attentions in recent years with having significant environmental benefit of CO2 geological storage and economic benefit of shale gas production. This paper is aimed at reviewing the state of experiment and model studies on gas adsorption, competitive adsorption of CO2/CH4, and displacement of CO2-CH4 in shale in the process of CO2-ESGR and pointing out the related challenges and opportunities. Gas adsorption mechanism in shale, influencing factors (organic matter content, kerogen type, thermal maturity, inorganic compositions, moisture, and micro/nano-scale pore), and adsorption models are described in this work. The competitive adsorption mechanisms are qualitatively ascertained by analysis of unique molecular and supercritical properties of CO2 and the interaction of CO2 with shale matrix. Shale matrix shows a stronger affinity with CO2, and thus, adsorption capacity of CO2 is larger than that of CH4 even with the coexistence of CO2-CH4 mixture. Displacement experiments of CO2-CH4 in shale proved that shale gas recovery is enhanced by the competitive adsorption of CO2 to CH4. Although the competitive adsorption mechanism is preliminary revealed, some challenges still exist. Competitive adsorption behavior is not fully understood in the coexistence of CO2 and CH4 components, and more experiment and model studies on adsorption of CO2-CH4 mixtures need to be conducted under field conditions. Coupling of competitive adsorption with displacing flow is key factor for CO2-ESGR but not comprehensively studied. More displacement experiments of CO2-CH4 in shale are required for revealing the mechanism of flow and transport of gas in CO2-ESGR.

With the development of localization technologies, researchers solve the indoor localization problems using diverse methods and equipment. Most localization techniques require either specialized devices or fingerprints, which are inconvenient for daily use. Therefore, we propose and implement an accurate, efficient and lightweight system for indoor direction finding using common smartphones and loudspeakers. Our method is derived from a key insight: By moving a smartphone in regular patterns, we can effectively emulate the sensitivity and functionality of a Uniform Antenna Array to estimate the angle of arrival of the target signal. Specifically, a user only needs to hold his smartphone still in front of him, and then rotate his body around 360 ∘ duration with the smartphone at an approximate constant velocity. Then, our system can provide accurate directional guidance and lead the user to their destinations (normal loudspeakers we preset in the indoor environment transmitting high frequency acoustic signals) after a few measurements. Major challenges in implementing our system are not only imitating a virtual antenna array by ordinary smartphones but also overcoming the detection difficulties caused by the complex indoor environment. In addition, we leverage the gyroscope of the smartphone to reduce the impact of a user’s motion pattern change to the accuracy of our system. In order to get rid of the multipath effect, we leverage multiple signal classification to calculate the direction of the target signal, and then design and deploy our system in various indoor scenes. Extensive comparative experiments show that our system is reliable under various circumstances.

The article aims to describe a methodology for studying the dynamic, stress-strain properties and density of core samples before and after exposure to hydrogen. The Stages of sample studies and the instruments used in laboratory experiments are examined on the example of core samples taken from the Bobrikov formations in the Volga-Ural oiland- gas bearing region. A comparative analysis of dynamic properties, density, Young's modulus and Poisson's ratio was carried out before and after ex-posure to hydrogen. It was discovered that after exposure to this gas, interval transit time of acoustic P-wave and S-wave through the samples decreased by an average of 2.4%; Young's modulus increased by 6.5%, while Poisson's ratio remained virtually unchanged. Besides, the research results demonstrat-ed an increase in sample density by 1.1%. The analysis of correlation dependencies revealed a typical change in interrelation of the parameters of P-wave interval transit time with Young's modulus and S-wave interval transit time after samples exposure to hydrogen. Overall, based upon the results of the studies of density, dynamic properties, and Young's modulus, there is evidence of weakening of the stressstrain properties in the core samples. However, such change does not have a major effect on their absolute values. Analysis of the results collected during laboratory experiments shows that the consid-ered horizon could potentially be the formation for the storage of a methane-hydrogen mixture. [ABSTRACT FROM AUTHOR]