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This study investigated the effects of freezing temperature on the failure modes of frozen sandstone under uniaxial compression loading conditions. First, the sandstone specimens were subjected to freezing treatments at different temperatures (e.g., 20, 0, − 5, − 10, − 15 and − 20 °C), and uniaxially compressed to failure in the frozen state. Subsequently, the real-time CT scanning was performed to observe the spatial three-dimensional and planar two-dimensional fracture morphology of the failed specimens. Next, the volumetric porosity and crack area were introduced to quantitatively describe the freezing temperature effects on the damage degree of specimens after compression failure. Finally, the box-counting dimension of cracks calculated by fractal theory and distribution images of crack orientation angle were used to quantitatively evaluate freezing temperature effects on the compression failure complexity of specimens. The results show that the tension-shear failure mode to shear failure mode occurs as temperature decreases, and the failure mode tends to be constant below − 10 °C. The volumetric porosity and crack area of the failed specimen decrease as temperature decreases. After specimen failure, the box-counting dimension of cracks decreases as temperature decreases, and the distribution range of crack orientation angle decreases, which indicates the failure complexity decreases. Highlights: Uniaxial compressive spatial failure modes of frozen sandstones were investigated. Tension-shear failure mode to shear failure mode occurred as temperature decreased. Failure mode tended to be constant as temperature decreased below − 10 °C. Compression failure complexity of specimens decreased as temperature decreased. [ABSTRACT FROM AUTHOR]

Presents information on a study which synthesized magnetic iron-bismuth multilayers by using electron-beam evaporation. Experimental procedures; Results of low-angle x-ray diffractometry analysis; Measurement of magnetization curves.

In rock engineering, the weakening effects of water on the stressed rock are nonnegligible. This paper studied the microstructure deterioration processes of sandstones under stress and stress-water coupling by real-time computed tomography (CT) technology and compared the difference in these two processes. Firstly, the real-time CT tests were performed on the dry and saturated sandstones during the uniaxial compression to study the progressive deterioration of sandstones caused by stress and stress-water coupling, which were further quantitatively described by porosity. Then, the equivalent radius was introduced to analyze the real-time pore structure characteristics of sandstones under stress and stress-water coupling. Finally, the difference in failure patterns of sandstones under stress and stress-water coupling was compared. The results show that the real-time CT images intuitively present the continuous changes of spatial morphology of defects in sandstones under stress and stress-water coupling. During the uniaxial compression, the porosities of dry and saturated sandstones decrease at first, then increase slowly and finally increase rapidly. However, as the increase of stress, the variation in porosity, shifting of pore size distribution curve and change of maximum equivalent radius interval of saturated sandstone are more significant, indicating that even under the same stress state, the water aggravates the microstructure deterioration of sandstone, thus leading to the reduction of bearing capacity of sandstone. In addition, the failed region of saturated sandstone is mainly composed of multiple shear and tensile cracks, which presents the typical tensile-shear composite failure. Highlights: Real-time CT tests were performed on sandstone during uniaxial compression. Real-time progressive failure process of sandstone was observed. Real-time pore distribution characteristic of sandstone was studied. Stress-water coupling effects on failure of sandstone were discussed. [ABSTRACT FROM AUTHOR]

In the rat model of heterotopic auxiliary liver transplantation, graft re-arterialization may influence the outcome of inter-liver competition. This was investigated in the current study using two transplanted groups with or without graft re-arterialization. Immediately after reperfusion, the re-arterialized grafts showed significantly higher bile flow rate and bilirubin excretion than the grafts without re-arterialization. DNA synthesis rate was also increased more drastically in the re-arterialized group following the transplantation. Without re-arterialization, the rats developed more pronounced cytolysis and cholestasis. Among the long-term survivors, all healthy re-arterialized grafts regenerated, whereas 5/6 non-re-arterialized grafts atrophied. These data demonstrate that the re-arterialization increases graft survival by improving early hepatic function, enhancing regenerative response and preventing post-transplant biliary complications in this rat model.Copyright © 2000 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Presents information on a study that calculated the total energy and electronic structure of the hexagonal-closed-packed Ni[sub75]Ta[sub25] metastable phase by the self-consistent discrete variational method and the local X α exchange approximation. Description on the theoretical method; Results and discussion on the study; Conclusion.

Presents a study which investigated the structures and magnetic properties of Co/Al multilayers prepared by means of planar magnetron sputtering. Sample preparation; Focus of previous studies on magnetic multilayers; Examination of the periodicity and crystallographic structure of the multilayers.

Although arterialisation of the portal vein has long been used in various surgical situations including treating patients with liver cirrhosis, hepatobiliary malignancy, and more recently in liver transplantation, the venous nature of the portal supply is considered essential to preserve hepatic integrity. Ninety-six Lewis rats were randomly assigned to four groups of twenty-four rats each. A standard 68% partial hepatectomy was performed in the rats of all groups to induce liver groups of twenty-four rats each. A standard 68% partial hepatectomy was performed in the rats of all groups to induce liver regeneration. Group 1 served as the control.