53 research outputs found

    Neoproterozoic to Paleozoic long-lived accretionary orogeny in the northern Tarim Craton

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    The Tarim Craton, located in the center of Asia, was involved in the assembly and breakup of the Rodinia supercontinent during the Neoproterozoic and the subduction-accretion of the Central Asian Orogenic Belt (CAOB) during the Paleozoic. However, its tectonic evolution during these events is controversial, and a link between the Neoproterozoic and Paleozoic tectonic processes is missing. Here we present zircon U-Pb ages, Hf isotopes, and whole-rock geochemical data for the extensive granitoids in the western Kuruktag area, northeastern Tarim Craton. Three distinct periods of granitoid magmatism are evident: circa 830–820 Ma, 660–630 Ma, and 420–400 Ma. The magma sources, melting conditions (pressure, temperature, and water availability), and tectonic settings of various granitoids from each period are determined. Based on our results and the geological, geochronological, geochemical, and isotopic data from adjacent areas, a long-lived accretionary orogenic model is proposed. This model involves an early phase (circa 950–780 Ma) of southward advancing accretion from the Tianshan to northern Tarim and a late phase (circa 780–600 Ma) of northward retreating accretion, followed by back-arc opening and subsequent bidirectional subduction (circa 460–400 Ma) of a composite back-arc basin (i.e., the South Tianshan Ocean). Our model highlights a long-lived accretionary history of the southwestern CAOB, which may have initiated as part of the circum-Rodinia subduction zone and was comparable with events occurring at the southern margin of the Siberian Craton, thus challenging the traditional southward migrating accretionary models for the CAOB

    Effects of Pressurized Superheated Steam Treatment on Dimensional Stability and Its Mechanisms in Surface-Compressed Wood

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    Shape stability is one of the most important properties of surface-compressed wood used as a substitute for other energy-intensive adhesives, concrete, and metals. This study evaluated the dimensional stability, surface wettability, chemical structure, cellulose crystalline structure, and microstructure of surface-compressed wood. The surface-compressed wood was then treated with pressurized superheated steam. The equilibrium moisture content, thickness swelling ratio, and wettability of the wood decreased by 20.39%, 30.63% (moisture absorption), 40.51% (water absorption), and 86.95% after pressurized superheated steam treatment, respectively. In the pressurized steam environment, hemicelluloses were significantly degraded, significantly reducing the strong hygroscopic groups, particularly hydroxyl groups. The crystallinity and crystal width of cellulose in the compressed wood also increased by 8.02% and 37.61%, respectively, after pressurized superheated steam treatment, corresponding to dimensional stability. Dimensional stability, namely the shape fixation of the surface-compressed wood, is a complex mechanism, including the hydrophobization of cell walls, the formation of cross-linkages, the reformation of microfibril chains, microstructural changes, and the relaxation of inner stresses, which reduced or even eliminated the recovery. This study demonstrates that pressurized steam treatment can effectively enhance dimensional stability in surface-compressed wood, which contributes to the substantial use of surface-compressed wood in the building and construction industries. We will further explore the relationship and mechanism between superheated steam pressure, treatment time, and dimensional stability

    Effects of Pressurized Superheated Steam Treatment on Dimensional Stability and Its Mechanisms in Surface-Compressed Wood

    No full text
    Shape stability is one of the most important properties of surface-compressed wood used as a substitute for other energy-intensive adhesives, concrete, and metals. This study evaluated the dimensional stability, surface wettability, chemical structure, cellulose crystalline structure, and microstructure of surface-compressed wood. The surface-compressed wood was then treated with pressurized superheated steam. The equilibrium moisture content, thickness swelling ratio, and wettability of the wood decreased by 20.39%, 30.63% (moisture absorption), 40.51% (water absorption), and 86.95% after pressurized superheated steam treatment, respectively. In the pressurized steam environment, hemicelluloses were significantly degraded, significantly reducing the strong hygroscopic groups, particularly hydroxyl groups. The crystallinity and crystal width of cellulose in the compressed wood also increased by 8.02% and 37.61%, respectively, after pressurized superheated steam treatment, corresponding to dimensional stability. Dimensional stability, namely the shape fixation of the surface-compressed wood, is a complex mechanism, including the hydrophobization of cell walls, the formation of cross-linkages, the reformation of microfibril chains, microstructural changes, and the relaxation of inner stresses, which reduced or even eliminated the recovery. This study demonstrates that pressurized steam treatment can effectively enhance dimensional stability in surface-compressed wood, which contributes to the substantial use of surface-compressed wood in the building and construction industries. We will further explore the relationship and mechanism between superheated steam pressure, treatment time, and dimensional stability

    A Spatio-Temporal Weighted Filling Method for Missing AOD Values

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    Aerosol Optical Depth (AOD) is a key parameter in defining the characteristics of atmospheric aerosols, evaluating atmospheric pollution, and studying aerosol radiative climate effects. However, a large amount of the AOD data obtained by satellite remote sensing are missing due to cloud cover and other factors. To obtain AOD data with continuous distribution in space, this study considers the spatial and temporal correlation of AOD and proposes a spatio-temporal weighted filling method based on a sliding window to supply the missing AOD data blocks. The method uses the semivariogram and autocorrelation function to judge the spatial and temporal correlation of AOD and uses the AOD spatial autocorrelation threshold as the sliding window size, and then it builds a spatio-temporal weighted model for each window to fill in the missing values. We selected the area with full values for simulation. The results show that the accuracy of this method has been significantly improved compared with the mean filling method. The R2 reaches 0.751, the RMSE is 0.021, and the filling effect is smoother. Finally, this method was used to fill in the missing values of the MultiAngle Implementation of Atmospheric Correction (MAIAC) AOD in the Beijing–Tianjin–Hebei region in 2019, and AErosol RObotic NETwork (AERONET) AOD was used as the true value for testing. The results show that the filled AOD has a high correlation with AERONET AOD, the R2 is 0.785, and the RMSE is 0.120. A summary of the AOD values of the 13 cities in the Beijing–Tianjin–Hebei region shows that the values in the first and third quarters are higher than those in the second and fourth quarters, with the highest AOD value in March and the second highest in August; among the 13 cities, the AOD values in Chengde and Zhangjiakou are lower than those in the other cities

    Common Variants in the TBX5 Gene Associated with Atrial Fibrillation in a Chinese Han Population.

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    PR interval variations have recently been associated with an increased risk of long-term atrial fibrillation (AF), heart block and all-cause mortality. Genome-wide association studies have linked the PR interval with several common variants in the TBX5 gene. Several variants in the TBX5 gene, including rs7312625 and rs883079, have been associated with AF. The purpose of this study was to determine the association of single-nucleotide polymorphisms (SNPs) in the TBX5 gene, rs7312625 and rs883079, with AF in Chinese Han patients.In this case-control association study, large cohorts of AF patients (n = 1132) and controls (n = 1206) were recruited from different hospitals. The genotyping was performed using a Rotor-Gene TM 6000 high-resolution melt system. Rs7312625, rs3825214 and rs883079 were analyzed. We found that SNP 3825214 was significantly associated with AF (P-obs = 0.002, odds ratio [OR] = 0.82), and lone AF (P-obs = 6.77x10-5, odds ratio [OR] = 0.71). SNP rs7312625 was significantly associated with lone AF (P-obs = 0.015, odds ratio [OR] = 1.27), although its association with AF was not significant. No significant association of SNP rs883079 with AF or lone AF was observed. Thus, we analyzed the interaction among these three loci. We demonstrated significant interaction among rs3825214, rs7312625 and rs883079. Four-locus risk alleles showed the highest odds ratio in combined rs3825214 and rs7312625 (P-obs<0.0001, odds ratio [OR] = 2.21). Six-locus risk alleles showed the highest odds ratio in combined rs3825214, rs7312625 and rs 883079(P-obs<0.0001, odds ratio [OR] = 2.35). Significance was established with the trend test (P<0.0001).For the first time, we report the strong association of SNP rs3825214 in the TBX5 gene with AF and lone AF in a Chinese Han population. Rs7312625 was significantly associated with lone AF, and snp-snp interaction increased the risk of atrial fibrillation. Our data might provide new insights into understanding AF pathogenesis and designing novel genetic therapies for AF patients
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