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The origin of dolostones from the Lei 4 Member (T2l4) of the Middle Triassic Leikoupo Formation in the Western Sichuan Depression is unclear. The occurrence and genetic evolution of dolostones in T2l4 were analysed by polarised thin-sections and cathodoluminescence, major- and trace-element, scanning electron microscope, and carbon, oxygen and strontium isotope analyses. The study results are summarised as follows. (1) The dolostones were mainly precipitated in three stages of <40 °C, 40–60 °C and 60–80 °C, corresponding with three paleodepth ranges of 167–300 m, 433–1000 m and 1067–1433 m. The micritic dolostones and the fabric-retentive dolostones (algal dolostone, granular dolostone) mainly formed in a near-surface–shallow-burial environment, and the crystalline dolostones were mainly formed under intermediate burial conditions. (2) 87Sr/86Sr ratios are equivalent to that of the Middle Triassic seawater, Sr/Ba and V/Ni ratios >1, Na notably higher than that in coexisting limestones of T2l4, and the dolostones always coexist with evaporative minerals such as gypsum, indicating that dolomitisation fluids mainly originated from evaporative concentrated seawater. (3) The dolostones mainly inherit materials from precursor limestones based on trace-element distribution patterns, and carbon and oxygen isotope values that are consistent with coexisting limestones of T2l4. (4) Mediated by micro-organisms during the syngenetic period, micritic dolostones and some algal dolostones were formed by replacing aragonites and calcites. During shallow burial, concentrated seawater rich in Mg2+ from the supratidal–intertidal zone flowed downward owing to gravity along the platform and replaced the underlying carbonate rocks, promoting continuous growth of the early dolomites. In the intermediate burial period, the Mg2+-depleted dolomitisation fluid caused the early micritic and silt-crystalline dolostones to recrystallise into silt- or fine-crystalline dolostones with larger crystals and altered the fabric-retentive dolostones into crystalline dolostones. (5) The evaporative dolostones deposited in the near-surface environment are characterised by maximal enrichment of Fe, Sr and Na, the highest δ18O values, the lowest order degree and the highest Ca/Mg ratios. The reflux dolostones formed in a shallow-burial environment characterised by the lowest Fe, medium δ18O values and the lowest order degree. The burial dolostones that developed in the intermediate burial environment are characterised by relative enrichment of Fe and Mn, minimal Na, the lowest δ18O values, the highest order degree and medium Ca/Mg ratios. The fabric-retentive dolostones mainly formed in a near-surface–shallow-burial environment, and the crystalline dolostones mainly formed under intermediate burial conditions. Dolomitisation fluids mainly originated from the evaporative concentrated seawater, and the dolostones inherit materials from the precursor limestones. Micritic dolostones were formed by evaporative dolomitisation; algal dolostone and granular dolostone were formed by evaporative dolomitisation and reflux dolomitisation; and silt-crystalline dolostone were formed by reflux dolomitisation and burial dolomitisation. [ABSTRACT FROM AUTHOR]

In order to obtain the optimal structure size of a microchannel heat sink (MCHS) with arc-shaped grooves and ribs according to the actual demand, multiple parameters that influence the performance of the microchannel are analyzed by combining the multi-objective evolutionary algorithm (MOEA) with computational fluid dynamics (CFD). The design variables include the relative groove height, relative rib height and relative rib width, and the two objective functions are to minimize the total thermal resistance and pumping power in constant volume flow rate. The influences of the design variables on the two objective functions are analyzed by CFD firstly. The results show that each design variable has a different impact on the two functions. The competitive relationship between the two objective functions is depicted in plots of the Pareto front obtained by MOEA. Pareto sensitivity analysis is carried out to find that the relative rib height has the most significant impact on the two objective functions. [ABSTRACT FROM AUTHOR]

The feasibility of naphthalene extraction from narrow distillates (205–225°C) of ethylene tar has been studied. Effects of extraction agent, extraction temperature, and extraction time on naphthalene yield have been investigated. The purity and qualitative analysis of naphthalene before and after extraction were measured through gas chromatography. The results showed that the naphthalene yield extracted by diglycol was up to 90% at the conditions of 8.0 extraction agent to raw material ratio, 70°C extraction temperature, and 50 min extraction time. The purity of naphthalene could reach 95% through double extraction. [ABSTRACT FROM AUTHOR]