Fracture behavior of wood plastic composite (WPC)

In this study, the effect of notch length on impact strength and fracture toughness was examined to exploit the use of wood plastic composite (WPC) as structural materials. Impact and fracture toughness test methods and estimation procedures were carried out. To evaluate the impact strength of WPC, five different notch sizes with two different fiber orientations on the load head were prepared. In terms of fracture mechanics, notch length was converted to stress concentration factor and the relationship between stress concentration factor and impact strength was determined. Fracture surface of impact specimens was investigated to evaluate the fracture mechanism of WPC by scanning electron microscopy (SEM). For the determination of fracture toughness of WPC, a short bar specimen with a rectangular cross section and a different notch size was used. To obtain the stress intensity factor (KI) for the mode I case, a finite element method (FEM) was carried out. The simulation of the stress intensity factor was performed on four successively refined meshes via quarter point elements around the crack tip. By means of an asymptotic analysis, the verification of the simulation was also presented. The experimental results showed that impact strength of WPC was highly dependant upon the fiber orientation and stress concentration factor. However, fracture toughness was independent of the change of the length of the notch. Fracture toughness of WPC was estimated to be 1.79 MPa√m using a four point bending test. The results of the simulation showed that stress intensity factor of WPC was estimated to be 584.9 (kPa√m). The results of normal stress at the crack tip from a common sequence of four successively refined meshes were diverged while the results of the stress intensity factors converged. The strength of singularity for normal stress (σx) was 4.92 which is quite close to that of true singularity (0.5) for the sharp crack tip when Θ=180°. Crack opening angle (COA) of the four point bending specimen was also estimated to be 50° on the basis of strength of singularity determined from finite element method

Who Is Caring for the Caregiver? The Role of Cybercoping for Dementia Caregivers

The purpose of this study is to investigate the relationship between dementia caregivers’ communication behaviors (information seeking and forwarding) and their outcomes (coping outcomes: e.g., dealing better with negative feelings or improved medical outcomes). A survey data set of dementia patients’ caregivers substantiates the effects of communication behaviors about dementia illness on coping outcomes, as well as the mediating role of emotion-focused and problem-focused coping processes. Using structural equation modeling (SEM), this study found positive effects of communication behaviors on outcomes through coping processes. Further, the results indicate that communication behaviors in cyberspace are crucial for caregivers to cope with dementia, both affectively (improvement of caregivers’ emotional control) and physically (health improvement of patients). The implications for the improvement of public health through online health communication behaviors are discussed

Modeling Differently Oriented Loblolly Pine Strands Incorporating Variation of Intraring Properties Using a Stochastic Finite Element Method

Wood strands are a biological material with variations in material properties because of the presence of earlywood and latewood, juvenile wood and mature wood as well as the sectional cut used to generate strands. This variation should be accounted for to produce reliable modeling results. This study used both a deterministic finite element method (FEM) and a stochastic finite element method (SFEM) to model the stiffness of wood strands from three different orientations (radial, tangential, and angled) incorporating intraring property variation from two growth ring positions. In addition, a homogeneous model was used as a control to compare the results from both deterministic FEM and SFEM. The homogeneous model predicted the stiffness well for radial and tangential orientation strands but provided unrealistic physical strain distributions. Assumptions of strand homogeneity oversimplified the strain distribution present in the strand, eliminating local maximum and minimum values. Cumulative probability curves comparing previous experimental results and SFEM results showed general agreement. Average differences in the effective tensile modulus of elasticity ranged 0.96-22.31%. Based on the modeling results, the earlywood tensile modulus of elasticity was the input parameter that had the greatest influence on the strand stiffness. The order of correlation of the earlywood and latewood Poisson ratios changed based on strand orientation. SFEM techniques provided accurate results and material property distributions as compared with the experimental results

Technical Note: Impact of Fertilization on Within-Tree Variability in Young Loblolly Pine (Pinus Taeda)

Density, ring width, and cell structure were analyzed at different sampling heights and growth ring numbers in a young loblolly pine tree (Pinus taeda) that had received multiple applications of fertilizer. Results indicated that earlywood and latewood tracheid length increased with increment of growth ring number and height, but fertilization did not appear to measurably influence cell length. As tree height increased, density decreased but latewood cell wall thickness increased. During the fertilization period, ring width and earlywood cell diameter increased, whereas density, latewood cell wall thickness, and latewood percentage decreased. Earlywood cell wall thickness did not appear to be influenced by fertilization and did not vary greatly with increment of growth ring number

Development of a Reporter System for In Vivo Monitoring of gamma-Secretase Activity in Drosophila

The gamma-secretase complex represents an evolutionarily conserved family of transmembrane aspartyl proteases that cleave numerous type-I membrane proteins, including the beta-amyloid precursor protein (APP) and the receptor Notch. All known rare mutations in APP and the gamma-secretase catalytic component, presenilin, which lead to increased amyloid betapeptide production, are responsible for early-onset familial Alzheimer\u27s disease. beta-amyloid protein precursor-like (APPL) is the Drosophila ortholog of human APP. Here, we created Notch- and APPL-based Drosophila reporter systems for in vivo monitoring of gamma-secretase activity. Ectopic expression of the Notch- and APPL-based chimeric reporters in wings results in vein truncation phenotypes. Reporter-mediated vein truncation phenotypes are enhanced by the Notch gain-of-function allele and suppressed by RNAi-mediated knockdown of presenilin. Furthermore, we find that apoptosis partly contributes to the vein truncation phenotypes of the APPL-based reporter, but not to the vein truncation phenotypes of the Notch-based reporter. Taken together, these results suggest that both in vivo reporter systems provide a powerful genetic tool to identify genes that modulate gamma-secretase activity and/or APPL metabolism

Improvement of Lipids and Reduction of Oxidative Stress With Octacosanol After Taekwondo Training

Athletes in combat sports undergo rapid changes in body weight prior to competition in order to gain a size advantage over their opponent. However, these large weight changes with concomitant high-intensity exercise training create poor lipid profiles and high levels of oxidative stress, which can be detrimental to health and sport performance. Therefore, the purpose of this study was to investigate the ability of the nutritional supplement octacosanol to combat the physiological detriments that occur in taekwondo players during rapid weight loss with high-intensity exercise training. Methods: A total of 26 male taekwondo players were randomly divided into 2 groups: An experimental group performed a 5% weight-loss and taekwondo training program with 40-mg octacosanol intake (OCT; n = 13) for 6 d, and a control group performed the same weight-loss and taekwondo training program with a placebo (CON; n = 13). Results: There were significant (P \u3c .05) group × time interactions for low-density lipoprotein and triglycerides, which significantly decreased (Δ18 [5] mg/dL and Δ80 [7] mg/dL, respectively), and high-density lipoprotein, which significantly increased (Δ10 [7] mg/dL), in the OCT group compared with the CON group. There were also significant (P \u3c .05) group × time interactions for superoxide dismutase (SOD), glutathione peroxidase (GPx), and malondialdehyde (MDA), with SOD increasing (Δ226 [121] U/gHb) in the OCT group, while GPx decreased (Δ20 [13] U/gHb) and MDA increased (Δ72 [0.04] nmol/mL) in the CON group. Conclusion: These results suggest that octacosanol may be a beneficial supplement to protect against the poor cholesterol levels and oxidative stress that occurs during taekwondo training

Large‐Scale, Ultrapliable, and Free‐Standing Nanomembranes

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97443/1/adma_201204619_sm_suppl.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/97443/2/2167_ftp.pd

Risk stratification of symptomatic brain metastases by clinical and FDG PET parameters for selective use of prophylactic cranial irradiation in patients with extensive disease of small cell lung cancer

Purpose: To identify risk factors for developing symptomatic brain metastases and evaluate the impact of prophylactic cranial irradiation (PCI) on brain metastasis-free survival (BMFS) and overall survival (OS) in extensive disease small cell lung cancer (ED-SCLC). Materials and methods: Among 190 patients diagnosed with ED-SCLC who underwent FDG PET/CT and brain Magnetic Resonance Imaging (MRI) prior to treatment, 53 (27.9%) received PCI while 137 (72.1%) did not. Prognostic index predicting a high risk of symptomatic brain metastases was calculated for the group without receiving PCI (observation group, n = 137) with Cox regression model. Results: Median follow-up time was 10.6 months. Multivariate Cox regression showed that the following three factors were associated with a high risk of symptomatic brain metastases: the presence of extrathoracic metastases (p = 0.004), hypermetabolism of bone marrow or spleen on FDG PET (p < 0.001), and high neutrophil-to-lymphocyte ratio (p = 0.018). PCI significantly improved BMFS in high-risk patients (1-year rate: 94.7% vs. 62.1%, p = 0.001), but not in low-risk patients (1-year rate: 100.0% vs. 87.7%, p = 0.943). However, PCI did not improve OS in patients at high risk for symptomatic brain metastases (1-year rate: 65.2% vs. 50.0%, p = 0.123). Conclusion: Three prognostic factors (the presence of extrathoracic metastases, hypermetabolism of bone marrow or spleen on FDG PET, and high neutrophil-to-lymphocyte ratio) were associated with a high risk of symptomatic brain metastases in ED-SCLC. PCI was beneficial for patients at a high risk of symptomatic brain metastases in terms of BMFS, but not OS. Thus, selective use of PCI in ED-SCLC according to the risk stratification is recommended. (C) 2020 Elsevier B.V. All rights reserved.

Biomimetic Thermal-sensitive Multi-transform Actuator

Controllable and miniaturised mechanical actuation is one of the main challenges facing various emerging technologies, such as soft robotics, drug delivery systems, and microfluidics. Here we introduce a simple method for constructing actuating devices with programmable complex motions. Thermally responsive hydrogels based on poly(N-isopropylacrylamide) (PNIPAM) and its functionalized derivatives (f-PNIPAM) were used to control the lower critical solution temperature (LCST) or the temperature at which the gel volume changes. Techniques for ultra-violet crosslinking the monomer solutions were developed to generate gel sheets with controllable crosslink density gradients that allowed bending actuation to specified curvatures by heating through the LCST. Simple molding processes were then used to construct multi-transform devices with complex shape changes, including a bioinspired artificial flower that shows blossoming and reverse blossoming with a change in temperature