Estimating work of adhesion using spherical contact between a glass lens and a PDMS block

This study proposes a method of estimating the thermodynamic work of adhesion using the spherical contact between a glass lens and a polydimethylsiloxane (PDMS) block. An equivalent stiffness of the measurement system is determined prior to the experimental measurements. Parameters such as force, contact radius, and displacement are measured during the contact processes that consist of a loading process and an unloading process. The elastic modulus of the PDMS is determined from the measured parameters. Hysteresis is observed in the contact process, showing that the process is in a non-equilibrium state. However, an equilibrium instant exists when the contact area attained a maximum value. The work of adhesion can be determined from the strain energy release rate using the parameters of the instant. The estimated work of adhesion is in the range estimated by another method. The limitation of the conventional method is also presented. The proposed method is suggested to be applicable to interface characterization in a practical adhesive contact with soft materials.     

Fast reconstruction of Bayesian iterative approximation in passive gamma-ray tomography

ABSTRACT

Median root prior expectation maximization (MRPEM) algorithm that belongs to the Bayesian iterative approximation is used in passive gamma emission tomography (GET) to reconstruct passive gamma emitter distribution. The algorithm converges slowly and may involve iterations of 50–200. Fast processing of the algorithm was integrated into MRPEM to accelerate the convergence. Then, the integrated MRPEM reconstructed a passive distribution of gamma emissions within a mock-up boiling water reactor (BWR) assembly. It was found that the reconstructions in GET using the integrated MRPEM could result in a 20% reduction in the mean absolute error (MAE) compared to the standard MRPEM.     

A Potential Serum N-glycan Biomarker for Hepatitis C Virus-Related Early-Stage Hepatocellular Carcinoma with Liver Cirrhosis

Detection of early-stage hepatocellular carcinoma (HCC) is beneficial for prolonging patient survival. However, the serum markers currently used show limited ability to identify early-stage HCC. In this study, we explored human serum N-glycans as sensitive markers to diagnose HCC in patients with cirrhosis. Using a simplified fluorescence-labeled N-glycan preparation method, we examined non-sialylated and sialylated N-glycan profiles from 71 healthy controls and 111 patients with hepatitis and/or liver cirrhosis (LC) with or without HCC. We found that the level of serum N-glycan A2G1(6)FB, a biantennary N-glycan containing core fucose and bisecting GlcNAc residues, was significantly higher in hepatitis C virus (HCV)-infected cirrhotic patients with HCC than in those without HCC. In addition, A2G1(6)FB was detectable in HCV-infected patients with early-stage HCC and could be a more accurate marker than alpha-fetoprotein (AFP) or protein induced by vitamin K absence or antagonists-II (PIVKA-II). Moreover, there was no apparent correlation between the levels of A2G1(6)FB and those of AFP or PIVKA-II. Thus, simultaneous use of A2G1(6)FB and traditional biomarkers could improve the accuracy of HCC diagnosis in HCV-infected patients with LC, suggesting that A2G1(6)FB may be a reliable biomarker for early-stage HCC patients.     

Gait event detection based on inter-joint coordination using only angular information

The detection of gait events with wearable sensors is necessary for a robotic system interacting with walking people. Conventional gait phase detection methods are based on machine learning. However, this method cannot detect a gait event every gait cycle because it is difficult to extract characteristic points. Additionally, using only angular information for detection is beneficial because angular information is needed for the control and evaluation of the robots. This paper proposes a novel algorithm for the detection of heel contact and toe-off using the inter-joint coordination of the hip, knee, and ankle joints that has a lower-dimensional structure. The proposed algorithm derives the four planes in the angular space and finds the switching points of the planes. Seven participants walked on force plates that measured the force of the foot against the floor. The error was less than 0.035 s when the gait events were detected after calculating planes using the first gait datum. The change in the patterns of the inter-joint coordination reflected the change in gait phases. Although the data were calculated offline, the results show that the heel contact and toe-off could be detected as soon as the angles were sensed once the planes were derived.     

Regulatory T Cells Exhibit Interleukin-33-Dependent Migratory Behavior during Skin Barrier Disruption

Regulatory T cells (Tregs) suppress immune responses and maintain immunological self-tolerance and homeostasis. We currently investigated relationships between skin barrier condition and Treg behavior using skin barrier-disrupted mice. Skin barrier disruption was induced by repeated topical application of 4% sodium dodecyl sulfate (SDS) on mice. The number of CD4⁺ forkhead box protein P3 (Foxp3)⁺ Tregs was higher in 4% SDS-treated skins than in controls. This increasing was correlated with the degree of acanthosis. The numbers of interleukin (IL)-10⁺ and transforming growth factor (TGF)-β⁺ Tregs also increased in 4% SDS-treated skins. Localization of IL-33 in keratinocytes shifted from nucleus to cytoplasm after skin barrier disruption. Notably, IL-33 promoted the migration of Tregs in chemotaxis assay. The skin infiltration of Tregs was cancelled in IL-33 neutralizing antibody-treated mice and IL-33 knockout mice. Thus, keratinocyte-derived IL-33 may induce Treg migration into barrier-disrupted skin to control the phase transition between healthy and inflammatory conditions.     

Empirical models for matrix cracking in a CFRP cross‐ply laminate under static‐ and cyclic‐fatigue loadings

This paper presents empirical models for predicting matrix crack density in a carbon fiber reinforced plastic (CFRP) cross‐ply laminate under static‐fatigue and cyclic‐fatigue loadings. First, a modified slow crack growth (SCG) law, that covers the whole range of stress ratio R of tension‐tension fatigue (0 ≤ R ≤ 1), was proposed. The modified SCG law and three conventional SCG laws were then combined with Weibull's probabilistic failure concept for predicting fatigue matrix crack density in a cross‐ply laminate. Matrix crack density was expressed as a function of R, the maximum stress in the transverse ply and the number of cycles. Next, fatigue tests were performed for R of 0, 0.2, 0.4, 0.6, and 1 to determine the applicability of these four models. Finally, constant fatigue life (CFL) diagrams were investigated based on the modified model. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Calcium isotope fractionation in liquid chromatography with crown ether resins

Breakthrough mode liquid chromatography was employed to study calcium isotope fractionation. Highly porous silica beads, the inner pores of which were embedded with a benzo-18-crown-6 ether resin or a benzo-15-crown-5 ether resin, were used as column packing material. For both the resins, enrichment of heavier isotopes of calcium was observed in the frontal part of their respective calcium chromatograms. The values of the isotope fractionation coefficient were on the order of 10^?3 and 10^?4 for the benzo-18-crown-6 ether and benzo-15-crown-5 ether resins, respectively. The observed isotope fractionation coefficient was dependent on the concentration of hydrochloric acid in the calcium feed solution; a higher hydrochloric acid concentration resulted in a smaller fractionation coefficient value. The present calcium isotope effects were most probably mass dependent, indicating they came from isotope effects based on molecular vibration. Molecular orbital calculations supported the present experimental results in a qualitative fashion.     

Stringiness morphology for crosslinked polyacrylic pressure-sensitive adhesives measured by peel testing with constant rate

To clarify the formation mechanism of front frame-type morphology, the stringiness of crosslinked random copolymers of poly(n-butyl acrylate-acrylic acid) during a 180° peel test with a constant tensile rate was examined for various crosslinker contents and rates using a quartz adherend. Cohesive failure occurred for lower crosslinker content and rate, whereas interfacial failure with sawtooth-type stringiness without a frame was observed for higher crosslinker content and rate. Front frame-type stringiness was formed at the boundary of cohesive and interfacial failures. To clarify the formation mechanism, observation was conducted from the start of peel test until the equilibrium state. The sawtooth-type stringiness with branches first formed at the tip. The adjoining branches were connected and the 2D frame was formed only on the adherend surface. The formed 2D frame developed toward the 3D walls and the front frame-type was then completed. This is caused by the surface tension that acts to restrain the increase in the surface area. However, the surface area of the front frame-type morphology was larger than the no frame-type. The larger absorption of peeling stress by the formation of this morphology is expected to contribute to peel strength improvement.