Influence of Fiber Volume Fraction on the Predictability of UD FRP Ply Behavior: A Validated Micromechanical Virtual Testing Approach.

Enhancing the understanding of the behavior, optimizing the design, and improving the predictability and reliability of manufactured unidirectional (UD) FRP plies, which serve as primary building blocks for structural FRP laminates and components, are crucial to achieving a safe and cost-effective design. This research investigated the influence of fiber volume fraction (vf) on the predictability and reliability of the homogenized elastic properties and damage initiation strengths of two different types of UD FRP plies using validated micromechanical virtual testing for representative volume element (RVE) models. Several sources of uncertainties were included in the RVE models. This study also proposed a modified algorithm for microstructure generation and explored the effect of vf on the optimal sizes of the RVE in terms of fiber number. Virtual tests were systematically conducted using full factorial DOE coupled with Monte Carlo simulation. The modified algorithm demonstrated exceptional performance in terms of convergence speed and jamming limit, significantly reducing the time required to generate microstructures. The developed RVE models accurately predicted failure modes, loci, homogenized elastic properties, and damage initiation strengths with a mean error of less than 5%. Also, it was found that increasing vf led to a concurrent increase in the optimal size of the RVE. While it was found that the vf had a direct influence on homogenized elastic properties and damage initiation strengths, it did not significantly affect the reliability and predictability of these properties, as indicated by low correlation coefficients and fluctuations in the coefficient of variation of normalized properties.

Transcutaneous electrical acupoint stimulation combined with an integrated perioperative nursing program prevents subsyndromal delirium in older patients after joint replacement.

OBJECTIVES: This study aimed to develop transcutaneous electrical acupoint stimulation combined with an integrated perioperative nursing program and evaluate its effects on preventing subsyndromal delirium (SSD) and postoperative delirium (POD) in older patients after joint replacement surgery. METHODS: Participants were randomly divided into two groups, the experimental group (n = 48) was given transcutaneous electrical acupoint stimulation combined with an integrated perioperative nursing program based on the routine care of the control group (n = 49). The incidence of SSD and POD in a week after surgery was recorded. Assessments of delirium severity, cognition, anxiety, and depression were also conducted at baseline and on postoperative day 7. RESULTS: The findings indicate that the intervention program had significant advances in alleviating the severity of delirium, cognitive impairment, anxiety, and depression but failed to reduce the incidence of SSD and POD. CONCLUSIONS: Our study indicated that TEAS combined with an integrated perioperative nursing program has a beneficial effect on alleviating symptoms of delirium, cognitive dysfunction, anxiety, and depression in older adults after joint replacement surgery.

Prediction of Damage Accumulation Effect of Wood Structural Members under Long-Term Service: A Machine Learning Approach.

It is well known that wood structural members can stand a relatively heavy load in the short term but will gradually get weaker if the load is applied for a longer period. This phenomenon is caused by the damage accumulation effect in wood and should be appropriately considered during the design of timber structures. Although various formulation methods (also known as classical models) have been proposed to evaluate the damage accumulation effect in wood, the calibration of model parameters is very time-consuming. Our work proposes a novel method to deal with the damage accumulation effect in wood that involves the application of machine learning algorithms. The proposed algorithm considers a multi-objective optimization process with a combination of goodness-of-fit and complexity. Long-term experimental data of typical wood species are used for developing the machine learning based damage accumulation model. Compared with existing pre-formulated models, our model managed to reduce the complexity of the model structure and give sufficiently accurate and unbiased predictions. This study aims to provide a novel tool for evaluating the damage accumulation in wood structural members, and the proposed model can further support the life-cycle performance assessment of timber structures under long-term service scenarios.

Pressure Ulcers in the Intensive Care Unit: An Analysis of Skin Barrier Risk Factors.

OBJECTIVE: The aim of this study was to determine whether skin barrier factors were associated with the common complication of pressure ulcers (PrUs) in intensive care unit (ICU) patients. It is unclear whether skin barrier factors influence the development of PrUs. PATIENT POPULATION: The sample was composed of 102 ICU patients (54 men, 48 women). The patients ranged in age from 23 to 88 years, with a mean age of 55.7 (SD, 19.1) years. METHODS: Demographic variables and the score for the Acute Physiology and Chronic Health Evaluation IV were recorded on admission. The Braden Scale assessment and measurements of the skin barrier factors were performed daily. Standard care for the prevention of PrUs was strictly administered, and PrUs that developed were evaluated according to the recommendations of the US National Pressure Ulcer Advisory Panel 2007 (Note: The authors used the 2007 recommendations at the time of their study.). Data were analyzed using descriptive statistics and logistic regression. RESULTS: The mean score for the Braden Scale was 11.2, and the incidence of PrUs was 31.4%. Lower moisture content of the stratum corneum and higher skin surface pH at the lower sacrum and hip were risk factors for PrUs, whereas scapular and heel skin barrier factors were not. CONCLUSION: Nursing strategies aimed at preventing PrUs should place added emphasis on the lower sacral and hip regions.

Mechanical Behavior of Dowel-Type Joints Made of Wood Scrimber Composite.

As a renewable building material with low embodied energy characteristics, wood has gained more and more attention in the green and sustainable building industry. In terms of material resource and physical properties, scrimber composite not only makes full use of fast-growing wood species, but also has better mechanical performance and less inherent variability than natural wood material. In this study, the mechanical behavior of bolted beam-to-column joints built with a kind of scrimber composite was investigated both experimentally and numerically. Two groups of specimens were tested under monotonic and low frequency cyclic loading protocols. The experimental results showed that the bolted joints built with scrimber composite performed well in initial stiffness, ductility, and energy dissipation. A three-dimensional (3D) non-linear finite element model (FEM) for the bolted beam-to-column joints was then developed and validated by experimental results. The validated model was further used to investigate the failure mechanism of the bolted joints through stress analysis. This study can contribute to the application of the proposed scrimber composite in structural engineering, and the developed FEM can serve as a useful tool to evaluate the mechanical behavior of such bolted beam-to-column joints with different configurations in future research.

Association between interleukin-6 gene polymorphisms and bone mineral density: a meta-analysis.

BACKGROUND: Many studies have examined the association between interleukin-6 (IL-6) gene polymorphisms and bone mineral density (BMD). However, the results remain conflicting. To assess the relationship more precisely, a meta-analysis was performed. METHODS: The PubMed, Embase, Chinese BioMedical Literature (CBM), Wanfang, and China National Knowledge Infrastructure (CNKI) database were searched for relevant articles published up to March 2013. Weighted mean difference (WMD) and 95% confidence interval (95% CI) were calculated using a fixed-effects or random-effects model. RESULTS: A total of 16 articles with 11,957 subjects were investigated in this meta-analysis. Overall, -634C/G polymorphism was significantly associated with BMD at the femoral neck (WMD, -0.016 g/cm(2); 95% CI, -0.028 to -0.003 g/cm(2)), lumbar spine (WMD, -0.049 g/cm(2); 95% CI, -0.069 to -0.030 g/cm(2)), and whole body (WMD, -0.023 g/cm(2); 95% CI, -0.037 to -0.009 g/cm(2)) for GG versus CC+CG. In subgroup analyses stratified by ethnicity, individuals carrying -634GG genotype had a significantly lower mean BMD at any skeletal site examined, compared with individuals with -634CC or -634CG genotype in Asian populations. For -174G/C polymorphism, the BMD differences between CC+CG and GG genotype were 0.004 g/cm(2) at the distal radius (95% CI, 0.004 to 0.005 g/cm(2)), 0.011 g/cm(2) at the trochanter (95% CI, 0.002 to 0.020 g/cm(2)), and 0.017 g/cm(2) at the Ward's triangle (95% CI, 0.003 to 0.032 g/cm(2)). No significant publication bias was observed in either the -634C/G or -174G/C polymorphism. CONCLUSIONS: This suggests that there are modest effects of the -634C/G and -174G/C polymorphisms on BMD. Large-scale and well-designed studies are required to further investigate gene-gene and gene-environment interactions on IL-6 polymorphisms and BMD in various populations.