Long-term settlement behavior of soft grounds and secondary compression

Abstract

Settlement–time behaviors in the last stage of consolidation are studied both in the laboratory and in the field. It is shown that the long-term settlement–time curves observed in the field are linear with the logarithm of time and the rate of the long-term settlement are analogous to the rate of secondary compression measured in a laboratory. The finite difference consolidation analyses for cohesive soils exhibiting large amounts of secondary compression during primary consolidation provide fairly good predictions of the settlement–time curves observed in the laboratory and in the field. In this paper, the applicability of the secondary compression model established in the laboratory is examined in in situ conditions. The initial rate of secondary compression used in this paper has a predominant influence on the settlement–time curve with different drainage distances. It is emphasized that the assumption for unknown secondary compression behaviors during the primary consolidation has a predominant influence on the settlement–time curve.     

GluN2B‐Selective N‐Methyl‐d‐aspartate (NMDA) Receptor Antagonists Derived from 3‐Benzazepines: Synthesis and Pharmacological Evaluation of Benzo[7]annulen‐7‐amines

Given their high neuroprotective potential, ligands that block GluN2B‐containing N‐methyl‐D ‐aspartate (NMDA) receptors by interacting with the ifenprodil binding site located on the GluN2B subunit are of great interest for the treatment of various neuronal disorders. In this study, a novel class of GluN2B‐selective NMDA receptor antagonists with the benzo[7]annulene scaffold was prepared and pharmacologically evaluated. The key intermediate, N‐(2‐methoxy‐5‐oxo‐6,7,8,9‐tetrahydro‐5H‐benzo[7]annulen‐7‐yl)acetamide ( 11 ), was obtained by cyclization of 3‐acetamido‐5‐(3‐methoxyphenyl)pentanoic acid ( 10 b ). The final reaction steps comprise hydrolysis of the amide, reduction of the ketone, and reductive alkylation, leading to cis‐ and trans‐configured 7‐(ω‐phenylalkylamino)benzo[7]annulen‐5‐ols. High GluN2B affinity was observed with cis‐configured γ‐amino alcohols substituted with a 3‐phenylpropyl moiety at the amino group. Removal of the benzylic hydroxy moiety led to the most potent GluN2B antagonists of this series: 2‐methoxy‐N‐(3‐phenylpropyl)‐6,7,8,9‐tetrahydro‐5H‐benzo[7]annulen‐7‐amine ( 20 a , K_i=10 nM ) and 2‐methoxy‐N‐methyl‐N‐(3‐phenylpropyl)‐6,7,8,9‐tetrahydro‐5H‐benzo[7]annulen‐7‐amine ( 23 a , K_i=7.9 nM ). The selectivity over related receptors (phencyclidine binding site of the NMDA receptor, σ₁ and σ₂ receptors) was recorded. In a functional assay measuring the cytoprotective activity of the benzo[7]annulenamines, all tested compounds showed potent NMDA receptor antagonistic activity. Cytotoxicity induced via GluN2A subunit‐containing NMDA receptors was not inhibited by the new ligands.     

SANS studies on catalyst ink of fuel cell

The structure of solid polymer electrode and catalyst ink of fuel cell has been investigated by focusing‐ (FSANS) and contrast‐variation small‐angle neutron scattering (CV‐SANS). The solid polymer electrode, consisting of carbon (C), platinum, and ionomer (polymer, P), exhibited a power‐law function with two asymptotes, i.e., from I(q) ～ q^?1 to I(q) ～ q^?4 with a crossover around q ≈ 0.005 Å^?1. The scattering functions of the catalyst ink, i.e., the polymer electrodes dispersed in water, were successfully decomposed to the corresponding partial structure factors, S_CC(q), S_PP(q), S_CP(q), exclusively representing C‐C, P‐P, and C‐P correlations. S_CC(q) was a monotonic decreasing function of q, dominating in the scattering from carbon clusters. On the other hand, S_PP(q) exhibited a scattering maximum characteristic of polyelectrolyte solutions. This suggests that ionic clusters in polyelectrolyte solutions are formed in catalyst ink. The cross term, S_CP(q), indicated that the carbon scattering is dominant and significant amount of ionomer is adsorbed on the carbon agglomerates. It is concluded that the catalyst ink consists of carbon agglomerates surrounded by ionomers and the presence of ionic‐cluster path plays a key role in the performance of the solid polymer electrodes in polymer electrolyte fuel cells. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39842.     

Determination of lamellar twisting manner in a banded spherulite with scanning microbeam X-ray scattering

We investigated lamellar twisting manner in a banded spherulite, the blend of poly-(?-caprolactone) and poly-(vinyl butyral), with scanning microbeam X-ray diffraction. We obtained the diffraction contour intensity map with a scanning pitch of 1 μm by employing a rotation of a spherulite around its radial direction along which the microbeam scans. The results confirm that the twisting manner depends on the crystallization temperature and that it changes from continuous twisting to step-wise twisting with the increase of crystallization temperature. Moreover, we observed that the phase of long-period lamellar twisting advanced by about 15° compared to that of short-period lamella. In addition, it was confirmed that c-axis of packing structure was normal to lamella, which was represented by dominant short-period lamella.     

Parallel Solution-Based Synthesis Approach for Search of Lanthanoid-Activated Ca2SnO4 Phosphor Materials

In the search for new fluorescent materials among lanthanoid-activated Ca₂SnO₄ compounds, a parallel solution-based synthesis approach was applied and a new blue-emission Ca₂SnO₄:Ce phosphor was discovered; its emission intensity reaches 80% of the intensity of one of the best commercial Y₃Al₅O₁₂:Ce³⁺ phosphors. Among 14 lanthanoid-activated materials, three categories could be distinguished with respect to the effect of the dopant ion on the excitation and emission properties of the phosphor. In addition, potential phosphors in the A–Sn–O (A=Mg, Ca, Sr, and Ba) systems were investigated and Ca₂SnO₄ was found to be the most suitable host compound for the lanthanoid-activated phosphors.     

Stabilizing nanometer scale tip-to-substrate gaps in scanning electrochemical microscopy using an isothermal chamber for thermal drift suppression

The control of a nanometer-wide gap between tip and substrate is critical for nanoscale applications of scanning electrochemical microscopy (SECM). Here, we demonstrate that the stability of the nanogap in ambient conditions is significantly compromised by the thermal expansion and contraction of components of an SECM stage upon a temperature change and can be dramatically improved by suppressing the thermal drift in a newly developed isothermal chamber. Air temperature in the chamber changes only at ~.2 mK/min to remarkably and reproducibly slow down the drift of tip-substrate distance to ~0.4 nm/min in contrast to 5-150 nm/min without the chamber. Eventually, the stability of the nanogap in the chamber is limited by its fluctuation with a standard deviation of ±0.9 nm, which is mainly ascribed to the instability of a piezoelectric positioner. The subnanometer scale drift and fluctuation are measured by forming a ~20 nm-wide gap under the 12 nm-radius nanopipet tip based on ion transfer at the liquid/liquid interface. The isothermal chamber is useful for SECM and, potentially, for other scanning probe microscopes, where thermal-drift errors in vertical and lateral probe positioning are unavoidable by the feedback-control of the probe-substrate distance.     

Analog CMOS implementation of a CNN-based locomotion controller with floating-gate devices

This paper proposes an analog CMOS circuit that implements a central pattern generator (CPG) for locomotion control in a quadruped walking robot. Our circuit is based on an affine transformation of a reaction-diffusion cellular neural network (CNN), and uses differential pairs with multiple-input floating-gate (MIFG) MOS transistors to implement both the nonlinearity and summation of CNN cells. As a result, the circuit operates in voltage mode, and thus it is expected to reduce power consumption. Due to good matching accuracy of devices, the circuit generates stable rhythmic patterns for robot locomotion control. From experimental results on fabricated chip using a standard CMOS 1.5-/spl mu/m process, we show that the chip yields the desired results; i.e., stable rhythmic pattern generation and low power consumption.     

Stabilization for thermomagnetic instability of CuNi/NbTi superconducting wire in spatially distributed magnetic field

Thermomagnetic instability in superconducting wires composing multistrand cables is a problem in the development of cables with large current capacity. This paper elucidates the quenching properties of ac superconducting wires in a distributed magnetic field applied to the strands in the cable, and the stabilization of the ac superconducting wires considering the effect of the longitudinal magnetic field or the fraction of copper embedded in each strand. First, the degradation of the quench current of CuNi/NbTi superconducting wires in a distributed magnetic field is exhibited with simple test samples. Second, the quench properties of the strand in a (6 + 1)³ cable and the optimal twist pitch of the cable for high stabilization are discussed. Last, the effect of copper on the quench properties of the strand and the appropriate fraction of copper for suppression of quench current degradation in a distributed magnetic field are discussed. © 2001 Scripta Technica, Electr Eng Jpn, 135(4): 26–34, 2001