Balance control during lateral load transfers over a slippery surface

Few studies have measured balance control during manual material handling, and even fewer with environmental cofactors. This study examined the effect of different surface frictions during a stationary manual material handling task. Thirty-six healthy participants completed 180° lateral transfer tasks of a load over high- and low-friction surfaces (μ = 0.86 and μ = 0.16, respectively). Balance measures, stance kinematics and lower extremity muscle activities were measured. Success during the novel slippery surface dichotomised our population, allowing us to investigate beneficial techniques to lateral load transfers over the slippery surface. Stance width reduction by 8 cm and 15° of additional external foot rotation towards the load were used to counter the imbalance created by the slippery surface. There was no clear alteration to lower extremity muscular control to adapt to a slippery surface. Changes in stance seemed to be used successfully to counter a slippery surface during lateral load transfers.

Statement of Relevance: Industries requiring manual material handling where slippery conditions are potentially present have a noticeable increase in injuries. This study suggests stance configuration, more so than any other measure of balance control, differentiates vulnerability to imbalance during material handling over a slippery surface.     

Effects of annealing on the polymer solar cells based on CdSe-PVK electron acceptor

CdSe-poly(N-vinylcarbazole) (CdSe-PVK) nanocomposite was synthesized and utilized as the electron acceptor in the active layer of polymer solar cells. The photovoltaic properties of the polymer solar cells based on poly(3-hexylthiophene) (P3HT):CdSe-PVK as the active layer were investigated in detail. The effects of annealing temperature (100-200 °C) and time (5-60 min) on the device performance were studied. At annealing temperature of 150 °C for 30 min, the device demonstrated an optimal efficiency of 0.235% under AM 1.5 (100 mW cm⁻²) solar simulated light irradiation. The improved efficiency under the optimal conditions was confirmed by the highest light harvest in UV-vis spectra due to the increased crystallinity of P3HT after thermal annealing. Photoluminescence of these devices also exhibited that the quench effect increases with the increasing of annealing temperature, indicating that the charge separation between electron-donating (P3HT) and electron-accepting (CdSe-PVK) molecules was increased after heat treatment. Atomic force microscopy (AFM) images showed that the phase segregation and 3D interpenetrating networks of P3HT:CdSe-PVK were responsible for the enhancement of the device efficiency.     

Friction and wear behavior of plasma assisted chemical vapor deposited nanocomposites made of metal nanoparticles embedded in a hydrogenated amorphous carbon matrix

Nanocomposite coatings consisting of preformed silver or chromium nanoparticles embedded into a hydrogenated amorphous carbon matrix (a-C:H) were synthesized by Electron Cyclotron Resonance plasma assisted Chemical Vapor Deposition (ECR-CVD). In a first step, the nanoparticles were distributed on silicon substrates by dipping in an ethanol suspension. In a second step, the ECR-CVD deposition of the a-C:H layer was done. The effect of the incorporation and the concentration on the friction and wear behavior was derived from unlubricated reciprocating sliding tests performed in ambient air. A decrease in the coefficient of friction, more intense with Cr incorporation, is induced by the preferential metal interaction with environment. In addition, for both metals, the coefficient of friction becomes lower as the metal concentration increases. A gradual increase in the coefficient of friction is detected for increasing the number of sliding cycles, which is attributed to the combined effect of surface smoothing and oxidation in the sliding contact. In conclusion, the valuable protective properties of the fullerene-like a-C:H coatings are enhanced by metal addition. As a consequence, a considerable reduction of the surface roughness and the volume loss in the wear tracks is especially noticeable for 10,000 cycles tests.     

Study on mixed‐mode fracture characterization in functionally graded materials

The fracture characterizations on mixed‐mode crack of functionally graded materials (FGMs) are investigated using digital speckle correlation method (DSCM). The stress intensity factors at mixed‐mode crack tip are obtained from digital speckle displacements fields. In combination with finite elements simulation results, the influences of gradient coefficients on fracture behavior of mixed‐mode cracks are analyzed. All the results show that the influence of gradient coefficients on fracture modes is not noticeable, and the stress intensity factor at the crack tip in graded materials are clearly influenced by the gradient coefficients, i.e., the stress intensity factors decrease with the increasing of gradient coefficients. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

扫描电镜在本科实验教学中初探

扫描电镜（SEM）是广泛应用于材料科学的精密贵重大型仪器,文章通过对本科实验教学中新开设的实验课进行设计及总结,初步探索出扫描电镜在本科实验教学中的可行性和重要性,结果表明,效果比较理想。     

木糖制备过程研究

文章对生产木糖的主要原料、主要工艺及木糖功用进行了综述，并提出利用农产品废弃物制备木糖工业生产的展望。     

Changes in microstructure,phases, and hydrogen storage characteristics of metal hydro-borate and nickel-added magnesium hydride with hydrogen absorption and release reactions

In this work, Zn(BH₄)₂ and/or Ni were added to MgH₂ in order to improve the hydrogen absorption and release properties of MgH₂. 99 wt% MgH₂ + 1 wt% Zn(BH₄)₂, 99 wt% MgH₂ + 0.5 wt% Zn(BH₄)₂ + 0.5 wt% Ni, and 95 wt% MgH₂ + 2.5 wt% Zn(BH₄)₂ + 2.5 wt% Ni samples [named MgH₂-1Zn(BH₄)₂, MgH₂-0.5Zn(BH₄)₂-0.5Ni, and MgH₂-2.5Zn(BH₄)₂-2.5Ni, respectively] were prepared by milling in a planetary ball mill in a hydrogen atmosphere. MgH₂-0.5Zn(BH₄)₂-0.5Ni had the highest initial hydriding and dehydriding rates and the largest quantities of hydrogen absorbed and released for 20 min. MgH₂-0.5Zn(BH₄)₂-0.5Ni dehydrided at the fourth cycle had small particles, large particles, and agglomerates. The sizes of the fine particles on the agglomerates were slightly smaller than those in the as-milled sample and quite flat surfaces of the agglomerates were not observed. MgH₂-0.5Ni-0.5Zn(BH₄)₂ dehydrided at 623 K under 1.0 bar H₂ at the 4th cycle contained Mg, MgO, and small amounts of β-MgH₂ and Mg₂Ni. The initial hydriding rates at n = 2, 3, and 4 were higher than that at n = 1. The quantity of hydrogen absorbed for 60 min, H_a (60 min), decreased as the number of cycles, n, increased. The initial dehydriding rate increased and the quantity of hydrogen released for 60 min, H_r (60 min), decreased as n increased. Outside the particles and agglomerates, particles became finer due to expansion and contraction, while in their interiors cracks were believed to coalesce due to annealing effect. MgH₂-0.5Ni-0.5Zn(BH₄)₂ had an effective hydrogen storage capacity (the quantity of hydrogen absorbed for 60 min) of about 5.5 wt% (5.52 ± 0.10 wt% at 593 K under 12 bar H₂). The PCT curve of MgH₂-0.5Ni-0.5Zn(BH₄)₂ showed that the hydrogen storage capacity was 6.64 ± 0.25 wt%.     

Robust microencapsulated phase change materials in concrete mixes for sustainable buildings

For passive building applications, phase change materials (PCMs) are microencapsulated to avoid leakage of PCM from concrete structure. The primary challenge of using microencapsulated PCM (MPCM) is its weak shell structure. New MPCMs with different shell compositions to prevent breakage during mixing in fresh concrete are needed. In this study, free radical polymerization method to microencapsulate capric acid–myristic acid mixture as PCM with two different methyl methacrylate co‐polymers is proposed to produce robust MPCMs for building applications. Two new microcapsules (MPCM‐1 and MPCM‐2) having latent heats of 91.9 and 97.3 J/g were synthesized. SEM analyses showed the size of microcapsules being in the range of 400–850 nm for MPCM‐1 and 250–475 nm for MPCM‐2. Analyses also reveal that the shells of MPCMs were not harmed, as they were added into concrete mixes. The microsphere's geometry was preserved, and distribution was homogeneous. The MPCMs were also studied under thermal tests of 1000 heating/cooling cycles. No significant changes in thermal properties were observed after thermal cycling tests. Copyright © 2016 John Wiley & Sons, Ltd.