Failure characteristics and conditions of rock-coal combination structure with weak layer under dynamic and static stresses.

To comprehensively understand the mechanical response of a rock-coal combination structure containing a weak layer, a series of laboratory static loading and impact loading experiments were conducted. The results showed that under static load, the sliding process of the rock coal structure was relatively slow, and fragments can be observed. Under the action of horizontal impact loading, the whole coal stratum slipped out rapidly, and the process lasted only 0.05 s. Under the horizontal and axial impact loads, the coal stratum remained stable first, and then it slipped out as a whole under the action of static load. Additionally, a sliding instability criterion of a rock coal structure containing a weak layer was established based on theoretical analysis. The key parameter P value was checked through a numerical simulation experiment. It was found that the value was linearly related to the mechanical properties of the weak layer and overburden stress, and the experimental results coincided with the theoretical results. Finally, the relationship between sliding rockburst and strain rockburst was discussed, and these results can provide an important scientific basis for the prevention and control of dynamic disasters in deep mining.

The permeability of shale exposed to supercritical carbon dioxide.

Permeability is a critical parameter of tight reservoir rocks and one of the important parameters for characterizing fluid flow and production from reservoirs. It determines the feasibility of its commercial development. SC-CO2 has been used in shale gas exploitation for efficient fracturing and the added benefit of CO2 geo-storage. And SC-CO2 plays an important role in permeability evolution of shale gas reservoirs. In this paper, Firstly, the permeability characteristics of shale under CO2 injection are discussed. The experimental results show that the relationship between permeability and gas pressure is not a single exponential relationship, but there is an obvious segmentation phenomenon, which is particularly obvious when it is close to the supercritical state, and the overall trend is first decreased and then increased. Subsequently, other specimens were selected for SC-CO2 immersion, and nitrogen was used to calibrate and compare shale permeability before and after treatment to assess changes in shale permeability after SC-CO2 treatment at pressures from 7.5 to 11.5 MPa and X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) were used to analyze the raw and CO2-treated shale particle sample, respectively. Results indicate the permeability increases significantly after SC-CO2 treated, and permeability growth is a linear function of SC-CO2 pressure. According to (XRD) analysis and (SEM) analysis, SC-CO2 not only can act as a solvent and dissolve carbonate minerals and clay minerals, but also can complex chemical reactions with mineral components in shale, Further dissolution of carbonate minerals and clay minerals, widened gas seepage channels and enhancing the permeability.

Experimental Study on the Methane Adsorption of Massive Shale Considering the Effective Stress and the Participation of Nanopores of Varying Sizes.

To explore the shale gas occurrence mechanism in shale with an intact pore structure under actual reservoir conditions, an adsorption experiment on massive shale was performed. Considering the change in the pore volume of massive shale under effective stress, the adsorption mechanism and free gas storage space of massive shale were investigated. Based on the adsorption mechanism assumptions of micropore filling and mesopore multilayer adsorption, the adsorbed phase densities of pores of varying pore sizes were calculated and applied to the conversion of the absolute adsorption amount of massive shale. The results show the existence of isolated pores in the massive shale, resulting in a lower adsorption capacity in comparison to granular samples. When subjected to the combined effects of in situ stress and pore pressure, the pore volume of massive shale gradually decreases with the increase in effective stress. Shale gas is mainly adsorbed in micropores, but with increasing pressure, the adsorption amount of micropores approaches saturation, and the contribution of mesopores to the total adsorption amount gradually increases. The main adsorption mechanism of shale gas is based on micropore filling, and the multilayer surface adsorption of mesopores should also be considered. By combining the simplified local density model and the Ono-Kondo lattice model, the adsorption behavior of shale gas can be accurately described. To accurately estimate shale gas reserves, it is necessary to take into account the actual pore size distribution, pore volume compressibility, and connected porosity of the shale samples.

Experimental study on ultrasonic irradiation for enhancing coalbed methane recovery.

The present study proposes the use of a new ultrasonic irradiation method to enhance permeability and desorption for gas recovery from low-permeability coal reservoirs. A triaxial stress ultrasonic irradiation test apparatus was developed specifically for coal, considering the properties of gas adsorption, migration, and sound intensity, and providing a simultaneous measurement of gas flux, to investigated the deformation and temperature of coal samples obtained from the Fuxin coal field by permeability and desorption experiments. With the ultrasonic irradiation duration, the permeability of coal improved gradually with unequal variation, accompanied by the Klinkenberg effect where it decreased rapidly and then increased slowly with increasing gas pressure. The ability to desorb coal was enhanced by higher sound intensity ultrasound irradiation, and the volume of gas desorption was much greater than that of the sample without mange, the temperature and strain were demonstrated as a "J shaped" curve. An X-ray computer tomography (CT) technique was used to visualise the meso- or macro-cracks in the coal sample at pre- and post- ultrasonic irradiation, consequently, fractures expanded under the irradiation of ultrasonic waves. A permeability and desorption model was developed to describe the improvement of coal seam gas production capacity under ultrasonic irradiation, which introduced effective sound pressure.

Temporary Trend, Characteristics and Clinical Outcomes of Acute Pancreatitis Patients Infected with Human Immunodeficiency Virus.

BACKGROUND: Compared to general population, human immunodeficiency virus (HIV) infection may increase frequency of acute pancreatitis (AP); however, evidence regarding effects of HIV infection on AP-related outcomes is limited and controversial. AIMS: We aim to investigate the temporary trend, characteristics and clinical outcomes of AP infected with HIV. METHODS: We reviewed data from the 2003-2014 National Inpatient Sample to identify patients with a primary diagnosis of AP. The primary outcomes (in-hospital mortality, acute respiratory failure, acute kidney injury, and prolonged length of stay [LOS]) and secondary outcomes (gastrointestinal hemorrhage, sepsis and total cost) were compared between patients with and without HIV infection using univariate, multivariable and propensity score matching analyses. RESULTS: Of 594,106 patients diagnosed with AP, 6775 (1.14%) had HIV infection. Patients with HIV were more likely to be younger, black, male, less likely to be gallstone-related and had lower rate of interventions. Multivariable analyses based on multiple imputation revealed that HIV infection was associated with higher risk of mortality (odds ratio [OR]: 1.74; 95% confidence interval [CI] 1.34-2.25), acute kidney injury (OR: 1.13; 95% CI 1.19-1.44), prolonged LOS (OR: 1.26; 95% CI 1.15-1.37) and 6% higher cost. There were no differences in sepsis, gastrointestinal bleeding, and respiratory failure between groups. CONCLUSIONS: HIV infection is associated with adverse outcomes including increased mortality, acute kidney injury and more healthcare utilization in AP patients. More assertive management strategies like early intravenous fluid resuscitation in HIV patients hospitalized with AP to prevent acute kidney injury may be helpful to improve clinical outcomes.

Enzymatic preparation of Crassostrea oyster peptides and their promoting effect on male hormone production.

ETHNOPHARMACOLOGICAL RELEVANCE: Crassostrea gigas Thunberg and other oysters have been traditionally used in China as folk remedies to invigorate the kidney and as natural aphrodisiacs to combat male impotence. AIM OF THE STUDY: Erectile dysfunction (ED) has become a major health problem for the global ageing population. The aim of this study is therefore to evaluate the effect of peptide-rich preparations from C. gigas oysters on ED and related conditions as increasing evidence suggests that peptides are important bioactive components of marine remedies and seafood. MATERIALS AND METHODS: Crassostrea oyster peptide (COP) preparations COP1, COP2 and COP3 were obtained from C. gigas oysters by trypsin, papain or sequential trypsin-papain digestion, respectively. The contents of testosterone, cyclic adenosine monophosphate (cAMP) and nitric oxide (NO) and the activity of nitric oxide synthase (NOS) in mice and/or cells were measured by enzyme-linked immunosorbent assays. Real-time PCR was used to assess the expression of genes associated with sex hormone secretion pathways. The model animal Caenorhabditis elegans was also used to analyze the gene expression of a conserved steroidogenic enzyme. In silico analysis of constituent peptides was performed using bioinformatic tools based on public databases. RESULTS: The peptide-rich preparation COP3, in which >95% peptides were <3000 Da, was found to increase the contents of male mouse serum testosterone and cAMP, both of which are known to play important roles in erectile function, and to increase the activity of mouse penile NOS, which is closely associated with ED. Further investigation using mouse Leydig-derived TM3 cells demonstrates that COP3 was able to stimulate the production of testosterone as well as NO, a pivotal mediator of penile erection. Real-time PCR analysis reveals that COP3 up-regulated the expression of Areg and Acvr2b, the genes known to promote sex hormone secretion, but not Fst, a gene involved in suppressing follicle-stimulating hormone release. Furthermore, COP3 was also shown to up-regulate the expression of let-767, a well-conserved C. elegans gene encoding a protein homologous to human 17-ß-hydroxysteroid dehydrogenases. Preliminary bioinformatic analysis using the peptide sequences in COP3 cryptome identified 19 prospective motifs, each of which occurred in more than 10 peptides. CONCLUSIONS: In this paper, Crassostrea oyster peptides were prepared by enzymatic hydrolysis and were found for the first time to increase ED-associated biochemical as well as molecular biology parameters. These results may help to explain the ethnopharmacological use of oysters and provide an important insight into the potentials of oyster peptides in overcoming ED-related health issues.

Couple-based collaborative management model of type 2 diabetes mellitus for community-dwelling older adults in China: protocol for a hybrid type 1 randomized controlled trial.

BACKGROUND: China's limited health care resources cannot meet the needs of chronic disease treatment and management of its rapid growing ageing population. The improvement and maintenance of patient's self-management is essential to disease management. Given disease management mainly occurs in the context of family, this study proposes to validate a Couple-based Collaborative Management Model of chronic diseases that integrates health professionals and family supporters; such as to empower the couples with disease management knowledge and skills, and to improve the couples' health and quality of life. METHODS: The proposed study will validate a couple-based collaborative management model of Type 2 Diabetes Mellitus (T2DM) in a community-based multicenter, two-arm, randomized controlled trial of block design in Guangzhou, China. Specifically, 194 T2DM patients aged ≥55 and their partners recruited from community health care centers will be randomized at the patient level for each center at a 1:1 ratio into the couple-based intervention arm and the individual-based control arm. For the intervention arm, both the patients and their spouses will receive four-weekly structured group education & training sessions and 2 months of weekly tailored behavior change boosters; while these interventions will be only provided to the patients in the control group. Behavior change incentives will be targeted at the couples or only at the patient respectively. Treatment effects on patients' hemoglobin, spouses' quality of life, alongside couples' behavior outcomes will be compared between arms. Study implementation will be evaluated considering its Reach, Effectiveness, Adoption, Implementation and Maintenance following the RE-AIM framework. DISCUSSION: This study will generate a model of effective collaboration between community health professionals and patients' family, which will shield light on chronic disease management strategy for the increasing ageing population. TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR1900027137, Registered 1st Nov. 2019.

Prevalence of Atrial Fibrillation in Hospital Encounters With End-Stage COPD on Home Oxygen: National Trends in the United States.

BACKGROUND: This study aimed to evaluate the prevalence of atrial fibrillation (AF) in hospital encounters with end-stage COPD on home oxygen admitted for COPD exacerbation. METHODS: We used the 2003 to 2014 Nationwide Inpatient Sample to conduct a retrospective analysis. This study included all patients ≥ 18 years of age with a primary diagnosis of COPD on home oxygen who were hospitalized for COPD exacerbation. We used multivariate-adjusted models to evaluate the association of AF with clinical factors, cost, length of stay, and hospital outcomes. RESULTS: In total, 1,345,270 patients were included; of these, 244,488 (18.2%) had AF. The AF prevalence increased from 12.9% in 2003 to 21.3% in 2014 (P < .0001) and varied by age, sex, race, income, insurance type, and hospital region. Advancing age, female sex, white race, high income, and large hospital size were associated with increased odds of AF. Presence of AF was a risk predictor for in-hospital death (OR, 1.54; 95% CI, 1.45-1.65), acute respiratory failure (OR, 1.09; 95% CI, 1.06-1.12), invasive mechanical ventilation (OR, 1.37; 95% CI, 1.29-1.47), noninvasive mechanical ventilation (OR, 1.14; 95% CI, 1.09-1.18), acute kidney injury (OR, 1.09; 95% CI, 1.04-1.13), sepsis (OR, 1.23; 95% CI, 1.10-1.37), and stroke (OR, 1.80; 95% CI, 1.40-2.32). AF was also associated with increased cost and length of stay. CONCLUSIONS: AF prevalence in hospital encounters with end-stage COPD increased from 2003 to 2014. Better management strategies for patients with end-stage COPD comorbid with AF are needed, especially in elderly individuals.

[Protective effect of Dendrobium candidum on isoproterenol induced cardiac hypertrophy in rats].

To study the effect and mechanism of Dendrobium candidum on isoproterenol-induced myocardial hypertrophy in rats, 60 healthy SD rats(30 males and 30 females) were randomly divided into 5 groups(12 in each group): normal group, model group, three D. candidum preventive administration groups(0.09, 0.18, 1.1 g·kg⁻¹). Except for the normal group, rats of other groups were injected back subcutaneously with ISO(5 mg·kg⁻¹) for 10 consecutive days. At the same time, preventive administration groups began to give different doses of the sample for 30 days and model group began to give normal saline. Left ventricular systolic pressure(LVSP) was measured in each group by common carotid artery cannulation, and the left ventricle(LW)/tibia length, heart weight index(HWI) and myocardial hydroxyproline(Hydro) content were calculated. Myocardial tissue HE staining and Masson staining were used to observe the myocardial structure and the degree of myocardial fibrosis respectively. Atrial natriuretic peptide(ANP), brain natriuretic peptide(BNP), and cardiac troponin I(cTN-I) concentration were measured by enzyme-linked immunosorbent assay(ELISA). The results showed that as compared with the normal group, the levels of ANP, BNP and cTN-I in plasma were significantly increased in ISO-induced hypertrophic rats; as compared with the model group, D. candidumcan inhibit ISO-induced ventricular pressure and ventricular hypertrophy, reduce myocardial collagen synthesis, improve myocardial fibrosis and ventricular remodeling, and significantly down-regulate ANP, BNP and cTN-I levels in plasma. This study shows that D. candidum has a protective effect on isoproterenol-induced cardiac hypertrophy.

[Comparative study on effects of rutin and quercetin on metabolism in osteoblast cells].

OBJECTIVE: To investigate the mechanism of rutin and its aglycone (quercetin) in preventing and treating osteoporosis and their effects on stimulating bone formation were studied comparatively in osteoblast cells. METHODS: The effects of rutin and quercetin on the proliferation, differentiation and mineralization were studied respectively by using tetrazolium (MTT), alkaline phosphatase (ALP) and mineralized nodules assays in newborn rat calvarial osteoblast (ROB) cells. RESULTS: Quercetin showed significant stimulatory effects on proliferation and mineralization in ROB cells, so it could promote bone formation. However, rutin could not imporve stimulation of bone formation because it increased proliferation and inhibited differentation and had no remarkable influence on ROB cells in vitro. CONCLUSION: Rutin showed less activity than quercetin on bone formation in ROB cells in vitro. Therefore the mechanism that some foods and traditional Chinese medicine containing rutin can prevent and treat osteoporosis is that its metaboite in vivo can promote bone formation in ROB cells.