Understanding User’s Switching Intention on Mobile Payment Platforms

With the development of mobile payment (m-payment) service, the competition accordingly increases among m-payment market. Users face multiple choices when adopting m-payment services. It is critical for both scholars and m-payments providers to understand what the underlying factors can influence user’s switching from one incumbent m-payment platform to another. To solve this question, we employ a push-pull-mooring (PPM) framework to build the research model. We propose that user’s dissatisfaction on incumbent m-payment provider is the main push factor for user’s switching. The attractiveness of alternative and peer influence are the pull factors influencing user’s switching. Cognitive lock-in, as the mooring factor, could influence switching intention directly. Additionally, we posit that cognitive lock-in can moderate the effects of both push and pull factors on user’s switching intention. This study will use survey methodology and structural equation modelling approach to test the hypotheses

Selenium status and cardiovascular diseases: meta-analysis of prospective observational studies and randomized controlled trials

Background/Objectives: Selenium was thought to have a role in cardiovascular disease (CVD) owing to its antioxidant properties; however, evidence from observational studies and randomized controlled trials (RCTs) has been inconsistent and controversial. We thus conducted a meta-analysis to assess the discrepancies between observational and randomized trial evidence. Subjects/Methods: We searched MEDLINE and EMBASE for eligible prospective studies regarding the relationship between selenium and CVD up to 15 December 2013 and finally included 16 prospective observational studies and 16 RCTs. Random effects model was used to estimate the pooled relative risk (RR). Generalized least-squares trend test and restricted cubic spline model were performed to assess a linear and a nonlinear dose–response relationship. Results: Our meta-analysis of prospective studies showed a nonlinear relationship of CVD risk with blood selenium concentrations across a range of 30–165 μg/l and a significant benefit of CVD within a narrow selenium range of 55–145 μg/l. Our meta-analyses of RCTs showed that oral selenium supplements (median dose: 200 μg/day) for 2 weeks to 144 months significantly raised the blood selenium concentrations by 56.4 μg/l (95% confidence interval (CI): 40.9, 72.0 μg/l), whereas oral selenium supplements (median: 100 μg/day) for 6 to 114 months caused no effect on CVD (RR=0.91; 95% CI: 0.74, 1.10). Conclusions: Our meta-analysis in prospective studies demonstrated a significant inverse association between selenium status and CVD risk within a narrow selenium range and a null effect of selenium supplementation on CVD was observed in RCTs. These findings indicate the importance of considering selenium status, dose and safety in health assessment and future study design

A Study on Contact Fatigue Performance of Nitrided and TiN Coated Gears

This paper discusses the effects of TiN coating on gear contact fatigue performance through contact fatigue experiment and gear rig test. The results reveal that the deposition on gears with hard coating TiN could provide the subsurface protection and improve the contact fatigue life, and the contact fatigue strength of nitrided+TiN coated 32Cr2MoV is 1557 MPa at survival probability of 99%, 284 MPa higher than that of nitrided 32Cr2MoV. Although TiN coating on the the edge of the meshing zone wore out, there is no obvious pitting at the site and the rest of meshed zone of TiN coated gear keeps well without pittings and wear grooves, which is opposite to nitrided gears with pittings and peeling off. TiN coating is dense and smooth with lower surface roughness, and it wraps up the gear tooth so that the gear surface no longer contacts with lubricant and prevents the cracks initiation, prolonging the contact fatigue life of gears

Experimental and numerical modeling of deformation-cracking mechanics of 3D-printed rock samples with single fracture

The analysis of mechanical response and deformation-cracking behavior contributes to the high-efficiency extraction of geo-energy and long-term safety of underground engineering structures. Compared to natural cores, the mechanical properties of 3D-printed samples made from quartz sand as raw material are relatively homogeneous, and can be used for quantitative studies on the influence of natural defects on the mechanical properties of rocks. In this work, 3D-printed samples with single fractures of different crack angles, lengths and widths were fabricated and used for uniaxial compression tests. Adopting the digital image correlation method, the stress-strain distribution during uniaxial compression tests were visualized, and the influence of prefabricated fracture characteristics (dip angle, length, and width) on the deformation-failure process were studied. An extended finite element method subroutine for ABAQUS® software was modeled and used for the uniaxial compression simulation, which was validated by experiments. Then, the influence of mechanical parameters (Young’s modulus, Poisson’s ratio, cohesion, and internal friction angle) on the deformation-cracking mechanics were simulated and studied. The results indicate that, compared to the intact sample, fractures reduce the sample strength. With the extension of fracture length and width, or the decline of fracture angle, both the peak strain and strength of the 3D-printed samples decrease. The splitting tensile failure, or shear failure, or both were determined for the 3D-printed samples with different fracture angles. For the same axial strain, the extension length of the new crack increases linearly with rising Young’s modulus and decreases linearly with increasing Poisson’s ratio. The initial strain of new cracks decreases linearly with increasing Young’s modulus, while little variations are found in samples with different Poisson’s ratio. For the same axial displacement load, the peak stress increases linearly with growing internal friction angle and cohesion.Cited as: Song, R., Tian, J., Wu, M., Liu, J. Experimental and numerical modeling of deformation-cracking mechanics of 3D-printed rock samples with single fracture. Advances in Geo-Energy Research, 2023, 8(2): 126-135. https://doi.org/10.46690/ager.2023.05.0

Associations of Muscle Mass and Strength with All-Cause Mortality among US Older Adults

INTRODUCTION: Recent studies suggested that muscle mass and muscle strength may independently or synergistically affect aging-related health outcomes in older adults; however, prospective data on mortality in the general population are sparse. METHODS: We aimed to prospectively examine individual and joint associations of low muscle mass and low muscle strength with all-cause mortality in a nationally representative sample. This study included 4449 participants age 50 yr and older from the National Health and Nutrition Examination Survey 1999 to 2002 with public use 2011 linked mortality files. Weighted multivariable logistic regression models were adjusted for age, sex, race, body mass index (BMI), smoking, alcohol use, education, leisure time physical activity, sedentary time, and comorbid diseases. RESULTS: Overall, the prevalence of low muscle mass was 23.1% defined by appendicular lean mass (ALM) and 17.0% defined by ALM/BMI, and the prevalence of low muscle strength was 19.4%. In the joint analyses, all-cause mortality was significantly higher among individuals with low muscle strength, whether they had low muscle mass (odds ratio [OR], 2.03; 95% confidence interval [CI], 1.27-3.24 for ALM; OR, 2.53; 95% CI, 1.64-3.88 for ALM/BMI) or not (OR, 2.66; 95% CI, 1.53-4.62 for ALM; OR, 2.17; 95% CI, 1.29-3.64 for ALM/BMI). In addition, the significant associations between low muscle strength and all-cause mortality persisted across different levels of metabolic syndrome, sedentary time, and LTPA. CONCLUSIONS: Low muscle strength was independently associated with elevated risk of all-cause mortality, regardless of muscle mass, metabolic syndrome, sedentary time, or LTPA among US older adults, indicating the importance of muscle strength in predicting aging-related health outcomes in older adults