ISSN 0253-2778

CN 34-1054/N

2023 Vol. 53, No. 5

Display Method:
2023-5 Contents
2023, 53(5): 1-2.
2023-5 Abstract
2023, 53(5): 1-2.
Earth and Space
Observation of MLT region winds and tides by the USTC Mengcheng meteor radar
Wen Yi, Xianghui Xue, Jie Zeng, Jianyuan Wang, Baozhu Zhou, Hailun Ye, Tingdi Chen, Xiankang Dou
2023, 53(5): 0501. doi: 10.52396/JUSTC-2022-0158
The atmospheric winds and waves in the mesosphere and lower thermosphere (MLT) region are essential for studying the dynamics and climate in the middle and upper atmosphere. The University of Science and Technology of China (USTC) meteor radar located at Mengcheng (33.36°N, 116.49°E) has been operating continuously since April 2014. More than 8 years of observation of mesospheric horizontal winds and tides are presented in this study. In addition, we present an intercomparison among the meteor radar observations and the Navy Global Environmental Model-High Altitude (NAVGEM-HA) analysis results. The meteor number at northern lower midlatitudes suffers from diurnal variations in meteor occurrence, with a high count rate in the local morning and a low rate during local afternoon-to-midnight. The meteor count rates show a clear annual variation, with a maximum in September–October and a minimum in February. The horizontal wind in the MLT region has dominant annual variations at lower midlatitudes, with the eastward wind during summer and the westward wind during winter above 84 km, and the eastward wind during winter and the westward wind during spring below 84 km. The meridional wind is northward during winter and southward during summer. The diurnal amplitude is dominant, followed by the semidiurnal tides at lower midlatitudes. The zonal and meridional diurnal tides show enhancements during spring (March) with amplitudes that can reach up to 40 m/s and 30 m/s and during autumn (September) with amplitudes that can reach up to 30 m/s and 25 m/s, respectively. The seasonal variations in diurnal tidal amplitude basically show characteristics that are strong during the equinox and weak during the solstice. The zonal and meridional semidiurnal tides are maximized during spring (April) and autumn (September) above 90 km.
Chromium isotope fractionation during adsorption of chromium(III) by soils and river sediments
Ziyao Fang, Xiaoqing He, Xi Yu, Liping Qin
2023, 53(5): 0502. doi: 10.52396/JUSTC-2022-0085
Chromium (Cr) isotope compositions of sedimentary rocks have been widely used to unravel fluctuations in atmospheric oxygen levels during geologic history. A fundamental framework of this application is that any Cr isotope fractionation in natural environments should be related to the redox transformation of Cr species [Cr(VI) and Cr(III)]. However, the behavior of Cr isotopes during non-redox Cr cycling is not yet well understood. Here, we present laboratory experimental results which show that redox-independent adsorption of Cr(III) by natural river sediments and soils can be accompanied by obvious Cr isotope fractionation. The observed Cr isotope fractionation factors (−0.06‰ – −0.95‰, expressed as 103lnα) are much smaller than those caused by redox processes. Combined with previous studies on redox-independent Cr isotope fractionation induced by ligand-promoted dissolution, we suggest that the systematic shift to highly fractionated Cr isotope compositions of sedimentary rocks is likely to represent atmospheric oxygenation, but muted signals observed in some geologic periods may be attributed to non-redox Cr cycling and should be interpreted with caution.
Diagenetic effects on strontium isotope (87Sr/86Sr) and elemental (Sr, Mn, and Fe) signatures of Late Ordovician carbonates
Dongping Hu, Dandan Li, Lian Zhou, Lilin Sun, Yilun Xu
2023, 53(5): 0503. doi: 10.52396/JUSTC-2022-0160
Understanding the effect and extent of diagenesis on the isotopic compositions of Sr in marine carbonates is a critical prerequisite for their use to unravel past environments. Here, we explore the dominant controls on carbonate 87Sr/86Sr of a Late Ordovician section from the Monitor Range, USA. Our results reveal a distinct increase in 87Sr/86Sr from 0.70794 to 0.70830 in the mid-upper D. ornatus zone, which is markedly higher than the published datasets of contemporaneous samples with a relatively lower and stable 87Sr/86Sr ratio of ~0.7079. These elevated 87Sr/86Sr ratios suggest a local and post-depositional overprint and cannot be interpreted to reflect the 87Sr/86Sr of the coeval seawater. Furthermore, 87Sr/86Sr exhibits statistically significant positive correlations with geochemical indicators for diagenesis ([Mn], [Fe], Mn/Sr, Fe/Sr), indicating that diagenetic alteration is the principal control on the observed radiogenic 87Sr/86Sr values. Using a numerical model of marine diagenetic fluid-rock interaction, we demonstrate that the observed Sr isotopic and elemental data can be best explained by the chemical variations in bulk carbonates associated with diagenetic alteration. Our results highlight that diagenesis may significantly alter the pristine 87Sr/86Sr ratios of carbonates than previously thought, although the samples satisfy the stricter geochemical criteria of Sr isotope preservation ([Sr] > 300 ppm, [Mn] < 300 ppm, [Fe] < 1000 ppm, Mn/Sr < 0.2, Fe/Sr < 1.6), pointing to the need for more caution when using bulk carbonate 87Sr/86Sr as a tracer of paleoenvironmental changes.
Harnack inequality for polyharmonic equations
Jiamin Zeng, Runjie Zheng, Yi Fang
2023, 53(5): 0504. doi: 10.52396/JUSTC-2022-0114
Some new types of mean value formulas for the polyharmonic functions were established. Based on the formulas, the Harnack inequality for the nonnegative solutions to the polyharmonic equations was proved.
New criteria of supersolubility of finite groups
Xueli Yang, Chenchen Cao, Chi Zhang
2023, 53(5): 0505. doi: 10.52396/JUSTC-2022-0132
We study the structure of finite groups in which some given subgroups are $\sigma$-embedded. In particular, we obtain some new criteria for the supersolubility of finite groups, which generalize some known results.
Research on the influence of social relations on social enterprise performance: The mediating role of business model innovation
Jianlin Wu, Wenhao Cai
2023, 53(5): 0506. doi: 10.52396/JUSTC-2022-0109
With the development of the social economy, social problems are becoming increasingly prominent. Solving social problems only by the government and public welfare organizations is difficult. Social enterprises offer opportunities for sustainable solutions to social problems; however, social enterprises generally face the problem of poor performance. Although previous studies provide some clues on the impact of social relations on social enterprise performance, whether social relations impact performance remains unknown, and the mechanism remains unclear. Based on resource-based theory, our study proposes the role of business model innovation as the intervening mechanism. Market information management capability enhances the positive effect of social relations on business model innovation. The findings from a survey of 198 Chinese social enterprises show that social relations have a significant positive impact on economic performance and social performance and that business model innovation plays a mediating role between social relations and performance. Market information management capability plays a positive moderating role between social relations and business model innovation. The research results enrich the research on the influencing factors of social enterprise performance, reveal the influencing mechanism and boundary conditions of social relations on social enterprise performance, and propose effective practical measures for improving social enterprise performance.
E-commerce cart recommendation effects: A field experiment on entertainment products
Yongjun Li, Yunjuan Zhang, Hanbing Xue
2023, 53(5): 0507. doi: 10.52396/JUSTC-2022-0130
This study aims to compare the effects of e-cart recommendation and homepage recommendation in the field of entertainment products on the basis of a field experiment involving almost 13000 consumers supported by one of the leading digital reading platforms in China. The results indicate that e-cart recommendations have a significant positive impact on consumer downloads in comparison with homepage recommendations. Moreover, this positive effect decreases when the alternatives in the e-cart are of a larger quantity but increases when consumers are more active. Interestingly, this study also finds that e-cart recommendations can spill over to other products, leading to more downloads of non-recommended items. Our findings provide novel insights into consumer responses to e-cart recommendations of entertainment products for researchers and managers alike.