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Inspired by the structure of cancellous bone and the nutrition metabolism of articular cartilage, we present a novel concept for a synthetic articular-cartilage-like material. The bioinspired material possesses a low coefficient of friction even under ultrahigh loads and has an extremely long lifetime. Furthermore, the composite shows zero-wear behavior and causes negligible wear damage to the friction pair. The superior tribological performance is attributed to the spontaneously generated articular-cartilage-like layer, which is constantly replenished by frictional heat and pressure. Our findings open a new area for industrial scale engineering applications to improve the friction and wear properties of moving components.

Shale gas in Upper Ordovician Wufeng Formation–Lower Silurian Longmaxi Formation in the Sichuan Basin is one of the key strata being explored and developed in China, where shale gas reservoirs have been found in Fuling, Weiyuan, Changning and Zhaotong. Characteristics of shale gas enrichment in the formation shown by detailed profiling and analysis are summarized as “high, handsome and rich”. “High” mainly refers to the high quality of original materials for the formation of shale with excellent key parameters, including the good type and high abundance of organic matters, high content of brittle minerals and moderate thermal evolution. “Handsome” means late and weak deformation, favorable deformation mode and structure, and appropriate uplift and current burial depth. “Rich” includes high gas content, high formation pressure coefficient, good reservoir property, favorable reservoir scale transformation and high initial and final output, with relative ease of development and obvious economic benefit. For shale gas enrichment and high yield, it is important that the combination of shale was deposited and formed in excellent conditions (geological construction), and then underwent appropriate tectonic deformation, uplift, and erosion (geological transformation). Evaluation based on geological construction (evolution sequence from formation to the reservoir) includes sequence stratigraphy and sediment, hydrocarbon generation and formation of reservoir pores. Based on geological transformation (evolution sequence from the reservoir to preservation), the strata should be evaluated for structural deformation, the formation of reservoir fracture and preservation of shale gas. The evaluation of the “construction - transformation” sequence is to cover the whole process of shale gas formation and preservation. This way, both positive and negative effects of the formation-transformation sequence on shale gas are assessed. The evaluation models based on this strategy would be more accurate, reliable and would avoid bias derived from indiscriminate and simplistic use of all parameters in the models.

Systematic Ce anomalies for whole-rock have been obtained from the shale-dominated, continuous, and pelagic sedimentary sequences spanning the Ordovician/Silurian (O/S) boundary at the Tieshui (铁水) of Xiushan (秀山), Chongqing (重庆), South China. Ce anomalies across the O/S boundary are recognized in three intervals, Wufeng (五峰), Guanyinqiao (观音桥) and Longmaxi (龙马溪). The calculated Ce/Ce* values of Wufeng Formation range from 0.84 to 0.96 (avg. 0.90). In the Guanyinqiao Formation, the values of calculated Ce/Ce* range from 0.73 to 0.85 (avg. 0.79). The Ce/Ce* values of uppermost Longmaxi Formation range from 0.87 to 0.96 (avg. 0.91). All along the section, the magnitude of the Ce anomaly is always negative, but is more significant in the Guanyinqiao Formation. The relatively higher Ce/Ce* values in the Wufeng and Longmaxi shales are likely to be due to the sediments deposited under rather reducing conditions. The Ce anomaly apparently does play some regular roles in the anoxic events that accompany prominent mass extinctions, and this work provides new data of critical importance for constraining models on the end-Ordovician anoxic events and mass extinctions.

The effect of pressure sensitivity index on the deformation behavior in Zr 41.2 Ti 13.8 Cu 12.5 Ni 10 Be 22.5 metallic glasses was studied using the indentation tests. The results showed that the intersecting slip lines occurred in the as-cast samples when the metallic glasses was deformed, and their shear band quantity, length, and density decreased with increasing the pressure sensitivity index in the annealed samples. The plastic deformation size of the as-cast sample is higher than that of the annealed samples under all the loads. It is therefore indicated that the pressure sensitivity index can affect strongly the deformation behavior and morphological characteristics of shear band of the metallic glasses.

The Chinese Tianshan is one of the important international natural laboratories for studying continental geodynamics, but its uplift time, kinematics and mechanism of formation are key unresolved questions. In order to constrain the timing, kinematics and mechanism of uplift of the Chinese Tianshan, we applied sedimentary petrography and apatite fission-track dating to Cretaceous-Tertiary series from the northern Tarim Basin and the Tianshan Mountains. We collected and analyzed 79 sandstone samples and 75 detrital heavy mineral samples from the Kezilenuer-Kuqa profile (northern Tarim Basin) with a well-defined magnetostratigraphy. Our data indicate that detrital mineral maturity abruptly decreased at the disconformity between the Upper and Lower Cretaceous, and decreased again after 15(−12) Ma. The sediments in the northern Tarim Basin changed their provenance at 124 Ma, 26(−24) Ma and 15(−12) Ma, respectively. In addition, we collected and analyzed 36 primary apatite samples from the South, Central and North Tianshan. Our results show that the Chinese Tianshan underwent three phases of differential uplift. The first phase of uplift started at the southern Central Tianshan during the Early Cretaceous and propagated southward. The second phase of uplift started at the northern Central Tianshan during the Late Cretaceous and propagated also southward. The third phase of uplift started at the northern Central Tianshan during the Eocene and propagated both northward and southward. These differential uplifts have caused development of disconformity and drops in mineral maturity of detrital sediments in the northern Tarim Basin. Such a differential and heterogeneous uplift process might have been trigged by collisions of different microcontinents (i.e., Lhasa, Kohistan-Dras and India) at the southern margin of Asia. These collisions reactivated the South Tianshan Fault and then the North Tianshan Suture, and uplifted the Chinese Tianshan step by step.

Pb0.35Sr0.65TiO3 (PST) thin films have been fabricated on LaAlO3 (LAO) and MgO substrates using the pulsed laser deposition technique. The microstructure characteristics of the films were examined by means of X-ray diffraction, atomic force microscopy, scanning electron microscopy and Raman spectroscopy, and the results indicate that the films are epitaxially grown and show good crystallinity. The dielectric constant dependence on DC bias voltage and temperature were measured in a planar capacitor configuration for these films. Compared to the PST thin film grown on LAO, the film grown on MgO showed a higher temperature of the capacitance maximum and a higher dielectric constant at zero bias. We explain the results by taking into account the lattice-mismatch strain between the substrate and the film. In contrast to the in-plane compressive strain induced by the LAO substrate, the in-plane tensile strain induced by the MgO substrate enlarges the unit cell of PST and enhances the magnitude of dipole moments, which increases the dielectric constant. These results indicate that a reasonable in-plane tensile strain could improve the dielectric properties of PST thin films. (c) 2006 Elsevier B.V All rights reserved.

Taking the Well JY1 and Well PY1 in the Eastern Sichuan Basin as examples, the formation mechanism of shale gas overpressure was studied by using the cross plot of acoustic versus density logging data. During the processes of hydrocarbon generation and the uplifting, the pressure evolution of fluids in shale gas layers was reconstructed by fluid inclusions and PVTSIM software. The major factors controlling the evolution of shale gas overpressure were established according to the study of fracture, the timing of the uplifting, and episodes of tectonic deformation. Our results showed that the main mechanism of overpressure in the Silurian shale gas reservoirs in the Sichuan Basin was the fluid expansion, which was caused by hydrocarbon generation. Since the Yanshanian, the strata were uplifted and fluid pressure generally showed a decreasing trend. However, due to the low compression rebound ratio of shale gas reservoir rocks, poor connectivity of reservoir rocks, and low content of formation water and so on, such factors made fluid pressure decrease, but these would not be enough to make up the effects of strata erosion resulting in a further increase in fluid pressure in shale gas reservoirs during the whole uplifting processes. Since the Yanshanian, the Well PY1 zone had been reconstructed by at least three episodes of tectonic movement. The initial timing of the uplifting is 130 Ma. Compared to the former, the Well JY1 zone was firstly uplifted at 90 Ma, which was weakly reconstructed. As a result, low-angle fractures and few high resistance fractures developed in the Well JY1, while high-angle fractures and many high resistance fractures developed in the Well PY1. In totality, the factors controlling the overpressure preservation in shale gas reservoirs during the late periods include timing of late uplifting, superposition and reconstruction of stress fields, and development of high-angle fractures.