•Local damage zone generated and propagated when the loading amplitude reached 80%.•Rock was prone to tensile failure under tension–compression cyclic loading.•Variation in parameters increased as ...the loading amplitudes increasing in tests.•Deformation was mainly concentrated inside local damage zone during cyclic loading.•Energy mainly dissipated for tensile cracks propagation inside local damage zone.
We have investigated the damage evolution and crack propagation of tuff rocks under axially cyclic tension–compression (T–C) loading with different amplitudes. The field of axial strains in the rock surface was obtained by three-dimensional digital image correlation (3D-DIC) method. The apparent strains were used to analyze the damage evolution along with the nucleation and propagation of microcracks until rock failure. The experimental results demonstrated that a local damage zone (LDZ) was formed when the loading amplitude exceeded a certain value, and the rock sample was prone to tensile failure under T–C cyclic loading. Based on arrangement of the virtual extensometers on the field of axial strains, the axial stress–strain curves, maximum axial strain, secant moduli, and dissipated energy evolution were obtained as a function of cycle number. It was observed that the variations in these mechanical parameters and dissipated energy significantly increased in the T–C cycle test with the increase in the loading amplitude. Particularly, due to obvious accumulation of residual compressive strain during the first cycle, the maximum tension stress increased, secant modulus decreased, and the dissipated energy evidently increased under tension during the second cycle. Furthermore, the mechanical parameters and dissipated energy evolution as a function of cycle number inside and outside the LDZ under 80% amplitude confirmed that the deformation mainly occurred inside the LDZ and the energy mainly dissipated for the nucleation and propagation of tensile microcracks vertical to the loading direction inside the LDZ during rock failure process.
The rock mass can be unstable due to the coupling effect of stress and seepage field, adversely affected by the geological field conditions. In this regard, this study implemented a 3D digital image ...correlation (3D-DIC) technique to conduct triaxial compression tests on sandstone samples under different seepage pressures. We analysed the evolution of strength and permeability during the rock failure process and space-time evolution of the surface radial strain. The results show that the strength and brittleness of the rock decrease with increasing seepage pressure. Further, the mechanical properties of the rock sensitive to were highly dependent on the seepage pressure. We also established a function model of permeability and axial strain consistent with the test results. By analysing the radial-strain-field of the rock surface at specific time points, we observed a gradual process of strain localisation instead of a sudden occurrence before failure. We extracted the spatial coordinates of the first 5% radial strain and subsequently conducted the spatial relation analysis by average-nearest-neighbour-analysis (ANNA). In addition, the approximate failure surface was fitted using the first 5% radial strain points in space, and the distance between the radial strain points and the fitted failure surface in space was analysed. This study shows that points with large strain values gradually converged towards the location of the fracture surface during the gradual failure process of the rock. Finally, this study provides a new method for predicting the failure zones of rock.
By studying the mechanical characteristics of sandstone, particularly its acoustic emission (AE) behaviour and fracture morphology, we can obtain insights into its deformation, stress, and fracture ...mechanisms, thus promoting knowledge in the field of geology. In this work, the mechanical properties of sandstone samples with different joint angles were investigated by applying shear force and observing the fracture propagation trend on a microscopic scale, using an AE-based technique. The experimental results demonstrated that the fracture expansion trend altered from a shearing fracture, which developed from the top to the lower areas of the samples, to a tensile fracture in the middle area of the samples and escalated in the angled joints; in particular, the severity of the fracture maximised at a joint angle of 60°. The energy released during the crack formation can be indicated by the decibels produced from the AE signal. While investigating the AE signals of the samples during shearing, it was determined that the decibels obeyed a Gaussian distribution centred at 50–69 dB. The surface fractures were macroscopically analysed through the self-defined fracture dispersion and fractal dimension, revealing that as the joint angle increased, the fracture dispersion initially increased and subsequently decreased, reaching its maximum at 60°, whereas the fractal dimension constantly increased. Through our investigation on the mechanical properties, main failure modes, AE characteristics, and microscopic features of sandstone, we aimed to elucidate the mechanisms responsible for fracture propagation both on a macroscopic and microscopic scale and provide theoretical insight in the field of geological disaster.
•The fracture propagation direction is related to the rock joint angles.•The rock shear failure pattern changes under different joint angles.•The failure of large joint angle rock is mainly caused by tensile fracture.•Acoustic emission signal decibels obey Gaussian distribution.•Using fractal and statistical methods to study the fracture extension.
In order to study the effect of water-rock interactions on shear strength characteristics, we performed shearing tests under varying hydrochemical environments. Moreover, a custom meso-shear test ...equipment for coal rock was used for the tests. Through 3D scanning of the shear fractures and scanning electron microscope imaging, we studied the effect of different pH chemical solutions on the shear strength and fracture characteristics of sandstones. We obtained three main results. With increasing solution acidity or alkalinity, water-hemical solution corrosivity increases. Moreover, the shear strength of sandstones reduces almost linearly and the fracture surfaces become smoother. The erosive effect is evidenced by the decrease in fracture surface fluctuations, roughness and the high-order microbulges, and scaling of the grain structure. A collection of characteristic parameters, including the maximum height S
, the root mean square deviation S
, the area ratio S
, and the slope root mean square S
, can be used to quantitatively describe the rough and irregular texture of the fracture surface.
Self-management intervention is an important component of disease management in patients with heart failure. It can improve heart failure knowledge, quality of life, and heart failure-related ...hospitalizations of heart failure patients. However, studies on the effect of two self-management interventions tasks have reported conflicting results.
This study conducted an up-to-date systematic review of the literature to evaluate the effects of self-management interventions on heart failure knowledge, quality of life, and heart failure-related hospitalizations in patients with heart failure.
Systematic review and meta-analysis.
We searched PubMed, Embase, Web of Science, Cochrane Library, and the references of articles in 14th December 2019.
The study characteristics included: authors, year, country, sample size, mean age of patients with heart failure, duration of intervention, recruitment and intervention delivery, interventions based on self-efficacy theory, cognitive behavioral therapy, disease management, self-care education. The risk of bias for each study was assessed independently by two investigators based on the Cochrane Handbook. This study used Revman to analyze different research outcomes. The fixed-effect model was used in the absence of significant heterogeneity or low heterogeneity, and if the heterogeneity was high, the random effect model was used.
A total of 4977 publications were retrieved in this study. After eliminating duplicates and screening for titles and abstracts, 209 articles were retrieved for full-text evaluation. Finally, a total sample size analyzed across 15 randomized controlled trials was 2630 participants. This study showed that self-management interventions significantly improved heart failure knowledge (0.61, 95% confidence interval (CI) 0.27–0.95, p = 0.0004), quality of life (0.20, 95% CI 0.02–0.38, p = 0.03), and heart failure-related hospitalization (OR 0.40, 95% CI 0.29 to 0.55, p<0.00001) in patients with heart failure.
This study reveals the beneficial effects of self-management interventions on heart failure knowledge, quality of life, and heart failure-related hospitalization in patients with heart failure. Therefore, high quality randomized controlled designs are needed to explore the optimal self-management interventions for patients with heart failure.
Tweetable abstract: This study reveals self-management interventions can improve heart failure knowledge, quality of life, and reduced heart failure-related hospitalization.
Long noncoding RNAs (lncRNAs) play multiple key regulatory roles in various cellular pathways. However, their functions in HIV-1 latent infection remain largely unknown. Here we show that a lncRNA ...named NRON, which is highly expressed in resting CD4(+) T lymphocytes, could be involved in HIV-1 latency by specifically inducing Tat protein degradation. Our results suggest that NRON lncRNA potently suppresses the viral transcription by decreasing the cellular abundance of viral transactivator protein Tat. NRON directly links Tat to the ubiquitin/proteasome components including CUL4B and PSMD11, thus facilitating Tat degradation. Depletion of NRON, especially in combination with a histone deacetylase (HDAC) inhibitor, significantly reactivates the viral production from the HIV-1-latently infected primary CD4(+) T lymphocytes. Our data indicate that lncRNAs play a role in HIV-1 latency and their manipulation could be a novel approach for developing latency-reversing agents.
In engineering geological disasters, the presence of water can accelerate rock mass fracture, and the state of the seepage field has a varying influence on the elastic behaviour of rock mass. A ...three-dimensional digital image correlation (3D-DIC) system is used to conduct triaxial compression tests on sandstone under different seepage conditions. The variation law of rock mechanical behaviour and the space–time evolution law of the surface radial strain field in the progressive failure process are analysed. The results show that, as the seepage pressure increases, the rock peak stress decreases and the Young's modulus increases, and the mechanical properties of the rock are easily affected by the varying seepage conditions. Meanwhile, a constitutive equation based on the Gumbel distribution, which can accurately reflect the axial stress–strain relationship in the rock failure process is established. By analysing the spatial distribution of virtual data points with large radial strain values at different times on the sample surface, a patent strain localisation phenomenon is identified in the progressive failure process of the rock. The localisation degree and extent of the failure area can be quantified using the average nearest-neighbour analysis (ANNA) and user-defined parameter S, which is used to normalise the average distance from the virtual data points to the fitted fracture surface. The results show that, with the continuous compression of samples under different seepage conditions, ANN decreases as S increases, and the large strain regional distribution is increasingly concentrated. The research results can be applied to predict surrounding rock failure areas in underground spaces and provide monitoring references with respect to engineering geological disasters under different seepage conditions.
•A 3D-DIC method was used to monitor the triaxial compression tests of sandstone under different seepage conditions.•A constitutive equation based on the Gumbel distribution was established.•Space-time evolution law of the surface strain field was analysed during the gradual failure process of the rock.
Abstract Background Previous research has revealed a negative association between social support and procrastination. However, few studies have investigated the mechanism underlying this relationship ...among vocational college students. Objective Based on the social cognitive theory, this study was intended to investigate the multiple mediating effects of self-efficacy and resilience on the relationship between social support and procrastination among vocational college students. Methods This study employed a cross-sectional design involving a sample of 1,379 students from a vocational college in China. Data were collected using the General Procrastination Scale, the Multidimensional Scale of Perceived Social Support, the General Self-Efficacy Scale, and the Resilience Scale-14. The PROCESS macro for SPSS was used to examine the multiple mediation model. Results Our findings indicate significant negative correlations between social support, self-efficacy, resilience, and procrastination. The multiple mediation analysis showed that social support did not have a significant direct impact on procrastination. Instead, the relationship between social support and procrastination was fully mediated by self-efficacy (indirect effect: -0.017; 95% CI: -0.032, -0.004) and resilience (indirect effect: -0.047; 95% CI: -0.072, -0.025), and sequentially mediated by both factors (indirect effect: -0.013; 95% CI: -0.020, -0.007). Conclusions The results emphasise the importance of enhancing self-efficacy and resilience in initiatives aimed at preventing and intervening in case of procrastination among vocational college students. Additionally, strengthening social support may also be crucial to preventing or reducing procrastination among this population.
Background
Cancer caregivers directly affect patient health outcomes. To maintain the function and health of caregivers so that patients can receive efficient care, we must pay more attention to ...caregivers’ quality of life in the process of caring for patients. However, the factors influencing caregivers’ quality of life are complex.
Aim
To assess caregivers’ quality of life in the process of caring for cancer patients and to explore the factors associated with it.
Design
This was a descriptive correlational study. A self-report questionnaire was used to anonymously collect data from one Chinese cancer hospital. The Functional Assessment of Chronic Illness Therapy-Spiritual Well-Being (FACIT-Sp-12), General Self-efficacy Scale (GSES), Positive and Negative Affect Schedule (PANAS), Connor-Davidson Resilience Scale 10 (CD-RISC-10), 24-item Caregiver Burden Inventory (CBI) and Caregiver Evaluation Questionnaire were used to measure caregivers’ spiritual well-being, self-efficacy, affective well-being, resilience, caregiver burden and quality of life. One-way analysis of variance, the Kruskal–Wallis H test and multiple regression analysis were applied to measure the factors influencing caregivers’ situations.
Setting and participants
A total of 315 caregivers of cancer patients were selected by convenience sampling. All participants were invited to complete the questionnaire through a one-on-one approach.
Results
The mean score for caregiver quality of life was 204.62 ± 36.61. After controlling for demographic factors, self-efficacy (β’ = 0.265,
p
< 0.01), resilience (β’ = 0.287,
p
< 0.01) and positive affect (β’ = 0.103,
p
< 0.01) were protective factors for caregivers’ quality of life. Negative affect (β’ = −0.217,
p
< 0.01) and caregiver burden (β’ = −0.219,
p
< 0.01) were negative factors. Notably, not all of these predictors can predict all dimensions of quality of life.
Conclusion
Caregivers’ quality of life needs to be further improved. The results of this study may provide clues to help identify factors influencing caregivers’ quality of life and implement targeted strategies to improve their quality of life.
•Circ_0005576 remarkedly increases in cervical cancer and most cell lines.•Circ_0005576 expression significantly correlates with the clinical parameters and poor prognosis in cervical ...cancer.•Circ_0005576 knockdown inhibits cervical cancer cell proliferation and mobility.•Circ_0005576 promotes cell mobility and proliferation through mir-153-3p/KIF20A axis.
Circular RNAs (circRNAs) are a novel group of noncoding RNAs characterized by a covalently closed loop. An increasing evidence suggests that deregulated circRNAs exert their essential regulatory roles in oncogenesis. However, little is explored on the biological role of novel circRNAs in cervical cancer (CC) progression. In the present study, we analyzed two GSE microarrays to screen for CC-specific circRNAs and found two circRNAs both expressed in CC cells and tissues. Among them, circ_0005576 was significantly overexpressed in both CC tissues and cell lines. Furthermore, upregulated circ_0005576 was positively associated with advanced FIGO stage, lymph node metastasis, but was negatively related with overall survival of CC patients. Additionally, circ_0005576 knockdown induced a suppressed cell growth, colony formation and metastasis of HeLa and SiHa cells. Mechanistically, circ 0005576 was mainly located in the cytoplasm and served as a sponge of miR-153-3p to increase kinesin family member 20A (KIF20A) expression. Rescue assays further validated the effects of circ_0005576/miR-153-3p/KIF20A axis on CC proliferation, migration and invasion. In conclusion, our research reveals a novel circ_0005576/miR-153-3p/KIF20A axis promoting CC progression, which may suggest a new insight into the pathogenesis of CC.
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