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In the context of internationalization, this longitudinal qualitative study explores the diverse and challenging experiences of Chinese international doctoral students in science, technology, engineering, and mathematics. The endeavor is to identify factors that facilitate or constrain their successful completion of a PhD abroad over time. By incorporating a three-dimensional multi-world conceptual framework that highlights the relationship between an individual's research, personal, and social worlds, this study identified six patterns of congruence or difference across the worlds and the corresponding transitions, illustrated with narratives for each pattern. Evidence shows that congruence of an individual's multi-worlds facilitates, but difference does not necessarily mean constraint when differences are respected, understood, and accommodated. Rather, it is how the transitions are negotiated that is important for the success of transnational and transcultural PhD study. This article contributes a conceptual framework, empirical evidence, and practical implications to the understanding of doctoral study abroad experiences.

Despite China's recent remarkable performance in high-quality research, the number of students going abroad to pursue doctoral degrees in STEM fields has been rising rapidly. This study investigates the motivations of Chinese international doctoral students (CIDS) in STEM fields for undertaking a PhD abroad, and the external factors influencing this major life decision. Based on in-depth interviews with 35 CIDS from seven universities in four Australian states, the findings show that for the current generation, enriching life experiences and self-cultivation emerged as most prominent personal motivations. The choice to study abroad, though ultimately a personal decision, was influenced by a range of factors and particularly long-term cooperation between host and home institutions. Both academic and personal reputation of supervisors played important roles in the selection of host institutions. This study may be of value to supervisors and higher education policy-makers, at institutional and government levels in all countries, whether "home" or "host", invested in sustainable international doctoral education.

The Oligocene-Miocene boundary Asian climatic reorganization linked to the northward migration of the East Asian monsoon into subtropical China is a potentially important but poorly constrained atmospheric CO2 consumption process. Here, we performed a first-order estimate of the CO2 consumption induced by silicate chemical weathering and organic carbon burial in subtropical China related to this climatic reorganization. Our results show that an increase in long-term CO2 consumption by silicate weathering varies from 0.06×1012 to 0.87×1012 mol yr−1 depending on erosion flux reconstructions, with an ~50% contribution of Mg-silicate weathering since the late Oligocene. The organic carbon burial flux is approximately 25% of the contemporary CO2 consumption by silicate weathering. The results highlight the significant role of weathering of the Mg-rich upper continental crust in East China, which would contribute to the rapid decline in atmospheric CO2 during the late Oligocene and the Neogene rise in the seawater Mg content. If this climatic reorganization was mainly induced by the Tibetan Plateau uplift, our study suggests that the growth of the Himalayan-Tibetan Plateau can lead to indirect modification of the global carbon and magnesium cycles by changing the regional hydrological cycle in areas of East Asia that are tectonically less active. [ABSTRACT FROM AUTHOR]

The Quaternary strata in North China primarily consist of fluvial sediments, which react strongly to East Asian Monsoon circulation. However, the records of the Quaternary climate change history in terms of these fluvial sedimentations were limited which impeded understanding the East Asian Monsoon evolution in North China. Thus, a 150 m deep drill core was collected from Changping in the Beijing plain to reconstruct the Quaternary palaeoenvironmental changes. The core was chronologically well constrained using palaeomagnetic and thermoluminescence dating. The magnetostratigraphic result indicated that the Brunhes/Matuyama boundary is at 134.2 m (0.78 Ma) and the age at the bottom of the core is 1.07 Ma. The thermoluminescence (TL) dating of the upper sand at ∼2 m was 10.4 ka. The chemical weathering history since the middle Pleistocene in Beijing plain was reconstructed by using geochemical proxies including selected major element pairs, chemical index of alteration and Al 2 O 3 –CaO*–(Na 2 O + K 2 O) diagrams. The CIA value of the Changping core ranged from 50.3 to 69.4 (average 59.2), which indicated that the sediment has experienced incipient to intermediate chemical weathering during the middle Pleistocene. The result of A–CN–K figure shows a high plagioclase to K-feldspar ratio in the source, which would be indicative of a granodiorite (Gd) source from Jundu Mountains north of the Beijing plain. All the geochemical results revealed a long-term gradual decrease of weathering since the middle Pleistocene, which implied a long-term increasing aridification/cooling in the Beijing plain. [ABSTRACT FROM AUTHOR]

Investigating geological structures has fundamental significance in engineering construction and the development of the urban economy. Limited by the circumstance related to human activities including the poor signal-to-noise ratio, buildings restricting accessibility, and surface conditions weakening sensor coupling, conventional geophysical methods are difficult to acquire high-precision geological structures, which is the premise and foundation of subway construction. The Passive surface waves method shows its preponderance in urban area surveys compared to conventional geophysical methods, especially in complex urbanized environments. Ambient noise caused by human activities can be considered as satisfying signals to perform surface wave dispersion energy calculation and explore shear wave velocity structure. In this study, 218 short-period seismometers were deployed as a four-line array crossing the planning subway of Line 22 in Guangzhou, Guangdong Province, south China. The spatial autocorrelation (SPAC) method, one of the passive surface-wave methods that can extract the dispersion curves from ambient noise data, is used to explore the distribution of the Guangsan Fault across the study area. The inverted velocity structure reveals that the linear array applied in the SPAC method with long-time seismic ambient noise record can retrieve reliable dispersion information to image subsurface geological structure. The three-dimensional result illustrated the distribution and characteristics of the Guangsan Fault matching well with previous geological references and revealed the Enping-Xinfeng Fault across the study area. The passive surface waves method has great potential for urban near-surface hidden fault investigation and can meet the demands of three-dimensional geological structure imaging with high precision. • The SPAC method has great potential for urban subsurface geological investigation. • Linear array in SPAC method with all azimuths data performs reliable inversion. • Near-surface faults in urban areas are detected by the passive surface waves method. [ABSTRACT FROM AUTHOR]

The paleolake that once existed in the Hetao Basin, China, represents an important stage of the Yellow River drainage system evolution in the region, but it has not been studied in detail to date. In particular, the formation and driving forces of the paleolake evolution since the late Pleistocene is still poorly understood. In this study, optically stimulated luminescence and radiocarbon dating were combined with multiproxy analysis of lacustrine sediments in the central Hetao Basin to reconstruct the paleolake evolution. Proxies included carbonate 18 O and 13 C isotopes, grain size, magnetic susceptibility, and color. In combination with stratigraphic records, the proxies indicated the existence of a lake environment in the Hetao Basin between ∼150 and ∼18 ka BP. The paleolake between 150 and 130 ka BP was an open system. Between 130 and 54 ka BP, the paleolake basin closed, with high lake levels at the beginning of the period and then a gradual decrease. After 54 ka BP, the paleolake began to outflow and gradually shrank in size, and after 18 ka BP an alluvial fan covered the region, and the paleolake disappeared. We propose a combination of tectonic uplift and climate changes as the main drivers of paleolake formation and evolution since the late Pleistocene. [ABSTRACT FROM AUTHOR]

Understanding the bulk organic carbon isotopic composition ( δ 13 C org ) of the surface soil in various climates is crucial for past climate reconstruction. Although the relationship between climatic factors (such as precipitation and temperature) and plant δ 13 C org are well studied at the global and regional scales, studies relating the surface soil organic matter δ 13 C org values and climatic factors remain relatively rare. In this study, 52 surface soil samples were collected from the Shiyang River drainage basin, the northeastern margin of the Tibetan Plateau, where changes in vegetation are sensitive to the climate. The δ 13 C org of the surface soils was analyzed to examine their environmental implications. Our results show that soil δ 13 C org values change from −26.58‰ to −21.73‰ with an average of −25.20‰ (±1.14‰). Binary regression analysis and linear regression analysis show that the change in the soil δ 13 C org values is significantly correlated with altitude; temperature and precipitation are responsible for the altitudinal impact on the soil δ 13 C org while air CO 2 concentrations have little effect. The sensitivity of the δ 13 C org values to the mean annual temperature is +0.066‰/°C and to the mean annual precipitation is −0.3‰/100 mm. We find that extremely low temperatures (above 2960 m a.s.l. in the study area) may result in physiological drought in plants even when precipitation is favorable, which consequently leads to higher soil δ 13 C org values. This observation is inconsistent with its direct positive role in the δ 13 C org values below 2960 m a.s.l., and the threshold is −1.2 °C in the Shiyang River drainage basin. In addition, the slope of the regression line for the soil δ 13 C org values versus altitude with favorable precipitation in our study is +1.2‰/km, which supports that a relationship of +1.1–1.3‰/km for the soil δ 13 C org values versus altitude is available on the Tibetan Plateau and the surrounding areas and further indicates that this coefficient in this region maybe potentially be useful for paleoelevation reconstruction. [ABSTRACT FROM AUTHOR]

Late Cenozoic sediments in the Linxia Basin of China, on the northeastern Tibetan Plateau, bear abundant fossils of the Hipparion fauna. From late Miocene times, these sections record a history of aridification in the Asian Interior, the evolution of the east Asian monsoon, and multiple uplifts of the Tibetan Plateau. In this paper, a new detailed magnetostratigraphic study of a sedimentary sequence from the Duikang (DK) section containing the Hipparion fauna is presented, to better understand interconnected ecologic and environmental changes. The 90-m-thick section reveals nine normal and nine reversed zones that span from chron. C5n.2n to chron. C3Ar or from chron. C4n.2n to chron. C2Ar, yielding magnetostratigraphic ages of ~8.1 Ma - 3.7 Ma for the studied section and 5.3 Ma for the Hipparion fauna-bearing bed. Combined with all the previous magnetostratigraphic ages of the fauna-bearing sediments in the Linxia Basin, Hipparion can be distinguished as mainly having lived during five periods: Phase I (11.5 Ma), Phase II (8.2 Ma), Phase III (6.3 Ma), Phase IV (~5.3 Ma) and Phase V (2.5 Ma). Based on comparison of climate records in the Linxia Basin with aridification records from surrounding regions and global cooling during the late Cenozoic, we suggest that the evolution of Hipparion from the Linxia Basin was mainly driven by continuous global cooling and tectonic uplift of the northeastern Tibetan Plateau since the late Miocene. • Depositional age of the DK section in the Linxia Basin is between 8.1 Ma and 3.7 Ma. • Hipparion lived during five different periods (11.5, 8.2, 6.3, 5.3 and 2.5 Ma). • Linxia Basin experienced the stepwise aridification since the late Miocene. [ABSTRACT FROM AUTHOR]

• The late Cretaceous–early Eocene paleoclimate of the Jianghan Basin was studied. • The salinity of the paleolake was mainly controlled by climate change. • The temporal differentiation of the evaporite deposits resulted from tectonics. • The widespread evaporites indicate an extremely arid climate during the Paleocene. • The climate became semi-humid during the early Eocene. The Jianghan Basin, Central China, contains a thick, continuous sequence of early Cenozoic evaporite-bearing deposits that provide a wealth of information about early Cenozoic climate change and evaporites accumulation in East Asia. However, the paleoclimatic history of the basin and its effect on the evaporites are largely unknown. We obtained a deep drill core (SKD1, 2346.5 m long) from the late Cretaceous to early Eocene evaporite-bearing deposits in the Jianghan Basin. Detailed analyses of the lithofacies, mineralogy and geochemistry of the core indicate that salinization and deepening of the lake occurred (corresponding to the Yuyang Formation to the lower Xingouzui Formation), followed by desalting and shallowing (corresponding to the upper Xingouzui Formation). Reconstruction of the spatiotemporal evolution of the evaporites in the Jiangling depression suggests a transition from semi-arid conditions in the late Cretaceous to extremely arid conditions in the initial stage of the Eocene. The climate then became semi-humid during the deposition of the upper Xingouzui Formation, indicating a monsoon or monsoon-like climate in East Asia during the early Eocene. The southward migration of the depocenter of the Jiangling depression, coupled with a warm and extremely arid climate, resulted in the precipitation of evaporites during the accumulation of the upper Shashi Formation and the lower Xingouzui Formation. These results indicate great potential for identifying potash resources within the subsag in the southern Jiangling depression. [ABSTRACT FROM AUTHOR]