Model Test and Consolidation Analysis of Failure of a Loose Sandy Embankment Dam During Seepage

Failures of earth dam embankments and river dikes, which are constructed of sandy soils with low dry densities, have been observed to occur during rising of water levels. In this paper, a large-scale physical model test was conducted in order to investigate the behavior of a small dam embankment as water levels rose. The test results were simulated by use of a consolidation analysis method coupled with an elastoplastic model for unsaturated soils. All parameters used in the simulation were obtained from element tests; oedometer, triaxial compression, soil water retention, and permeability tests. First, in order to verify the parameters identified, direct shear tests were simulated using the consolidation analysis method; results of the simulation and the tests were consistent. From the embankment model test it was found that the crest of the embankment moved upstream at the first stage of impounding and then moved back. After a seepage surface appeared on the downstream slope, tension cracks occurred on the downstream slope, and sliding occurred through the crack and the downstream toe. The results of the simulation were consistent with those of the model test. This consolidation analysis method could be used to simulate the complex deformations induced by saturation collapse and shear strains and even failure behavior. Old embankments constructed with loose densities might have histories in which cracks occurred on the downstream slopes when the reservoir water level rose, and their stabilities might have decreased.     

Fabrication of Nonadditive Mica Ceramics by Hot Isostatic Processing

Powder compacts of synthetic mica (fluorphlogopite) encapsulated in a boro–silicate glass tube were isostatically hot–pressed in a Roy–Tuttle–type pressure vessel. Synthetic mica was sintered to a density of 2.60 g/cm³ (91.2% of theoretical density) without additives under 98 MPa of water at 800°C for 45 min.     

Fabrication of uniform Al-Pb-Bi monotectic alloys under microgravity utilizing the Space Shuttle: microstructure and superconducting properties

Al-Pb-Bi monotectic alloys with three different compositions were melted and solidified under a microgravity environment in the Space Shuttle. The (Pb, Bi) particles were dispersed uniformly in the aluminium matrix, while evident sedimentation was observed in the reference sample processed under 1 G. Slow cooling was also effective to obtain homogeneous microstructure because of the absence of Marangoni force. The alloys were cold-worked into wires and the superconducting properties of the wires were investigated. The distance between (Pb, Bi) fibres for the alloys prepared under microgravity was so small that the wires showed complete zero resistance below 9 K due to the proximity effect.     

Synthetic approach to alloy thermodynamics and kinetics by cluster variation method and path probability method

The cluster variation method of equilibrium thermodynamics is employed to calculate the Ll₀-disorder phase diagram. The stability analysis based on the second-order derivative of the free energy functional with respect to the deviation of correlation functions from their equilibrium values yields the 100 instability locus in the phase diagram. The time evolution of cluster probabilities at the phase transition is investigated on the basis of the path probability method of non-equilibrium statistical mechanics. Thereby the synthetic study of thermodynamics and kinetics based on the cluster variation method and the path probability method is attempted. It is shown that the fluctuation is necessary to drive the ordering reaction above the instability temperature, whereas the spinodal-like ordering transition takes place below the instability temperature. The extension of the present study of a spin system to an alloy system is briefly discussed and a critical problem to be settled is pointed out.     

Is outer arm dynein intermediate chain 1 multifunctional?

The outer arm dynein of sea urchin sperm axoneme contains three intermediate chains (IC1, IC2, and IC3; M(r) 128,000, 98,000, and 74,000, respectively). IC2 and IC3 are members of the WD family; the WD motif is responsible for a protein-protein interaction. We describe here the molecular cloning of IC1. IC1 has a unique primary structure, the N-terminal part is homologous to the sequence of thioredoxin, the middle part consists of three repetitive sequences homologous to the sequence of nucleoside diphosphate kinase, and the C-terminal part contains a high proportion of negatively charged glutamic acid residues. Thus, IC1 is a novel dynein intermediate chain distinct from IC2 and IC3 and may be a multifunctional protein. The thioredoxin-related part of IC1 is more closely related to those of two redox-active Chlamydomonas light chains than thioredoxin. Antibodies were prepared against the N-terminal and middle domains of IC1 expressed as His-tagged proteins in bacteria. These antibodies cross-reacted with some dynein polypeptides (potential homologues of IC1) from distantly related species. We propose here that the three intermediate chains are the basic core units of sperm outer arm dynein because of their ubiquitous existence. The recombinant thioredoxin-related part of IC1 and outer arm dyneins from sea urchin and distantly related species were specifically bound to and eluted from a phenylarsine oxide affinity column with 2-mercaptoethanol, indicating that they contain vicinal dithiols competent to undergo reversible oxidation/reduction.     

First-principles calculations of phase equilibria and transformation dynamics of Fe-based alloys

Theoretical procedures of first-principles calculations of phase stability and phase equilibria are summarized. The present scheme is shown to be able to reproduce the transition temperatures with surprisingly high accuracy for Fe−Pd and Fe−Pt systems. The main emphasis of the present report is placed on the extension of the first-principles calculation to transition dynamics calculations. This is performed by combining the cluster variation method with the phase-field method via a coarse graining operation. The time evolution process of antiphase boundaries associated with L1₀ ordering for Fe−Pd system is demonstrated. This paper was presented at the International Symposium on User Aspects of Phase Diagrams, Materials Solutions Conference and Exposition, Columbus, Ohio, 18–20 October, 2004.     

Pulmonary vascular disease and operative indications in complete atrioventricular canal defect in early infancy

Pulmonary vascular disease was morphometrically analyzed in 67 patients (mean age, 19 months) with isolated complete atrioventricular canal defect. Complete obstruction of the small pulmonary arterial lumen resulting from acute fibrous proliferation and atrophy of the peripheral arterial media, which were considered absolute operative contraindications, were characteristic in six patients with Down's syndrome. Morphometric analysis of medial thickness revealed that thinning of the media of the small pulmonary arteries is generally observed at around 6 months of age in patients with complete atrioventricular canal defect and that the media in patients who have complete atrioventricular canal defect and Down's syndrome was thinner than that in such patients without Down's syndrome. These results suggest that thinning of the media as a result of two factors--Down's syndrome and aging--facilitates the rapid occurrence of fibrous intimal proliferation. Therefore intracardiac repair is desirable within 6 months of life, before medial thinning, in patients with complete atrioventricular canal defect and Down's syndrome. Excluding patients with absolute operative contraindications, the scores of the index of pulmonary vascular disease in operative survivors were below 2.0 and death occurred when scores were more than 2.2. The pulmonary vascular resistances measured in room air and by the oxygen inhalation and tolazoline tests in patients with operative contraindications were more than 7.3, 3.8, and 6.6 units.m2, respectively. We thus conclude that lung biopsy should be undertaken for patients in whom pulmonary vascular resistance is beyond these values to determine the appropriateness of surgical intervention.