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Between 1958 and 1999, notable lithic localities recorded prehistoric activities in Xiqiao Town of Nanhai District, Foshan City, Guangdong Province, from which double-shouldered and microlith-stone artefacts were uncovered. Currently, the "Xiqiaoshan site" is recognized as a substantial Neolithic quarry and processing location, dating back to 4‒7 ka B P. Subsequently, from 2011 to 2022, we conducted multiple geological environmental surveys and analyses on Xiqiaoshan Mountain. A well-preserved Quaternary stratigraphic profile was discovered north of Fuxian village in the southeast foothills of Xiqiaoshan Mountain. The sedimentological, geochemical, and geochronological results indicate the presence of two primary sedimentary strata in the Fuxian locality. The upper unit comprises the Holocene swamp facies, with a calibrated AMS14C dating range from 5052‒5409 a B P; whereas, the lower unit comprises the late Pleistocene alluvial-diluvial strata, with a calibrated AMS14C dating range from 38420‒40502 a B P, and an optically stimulated luminescence (OSL) dating range of 41.977‒43.796 ka B P. Late Pleistocene strata yielded two sand-gravel layers containing Paleolithic artefacts, which are marked as layers A1 and A2. The predominant artefacts in lower layer A1 include larger scrapers, pointed tools, tongue-shaped edged tools, and small flake tools, such as various scrapers, denticulates, notches, knives, utilized flakes, and cores, including tanged axe-shaped knives. In the upper layer A2, backed or tanged knives appear more frequently. The other small flake tools from this layer (A2) were not significantly different from those in lower layer A1. One bifacially prepared core for producing small elongated flakes is of particular interest for this artefact. Based on the average deposition rate, the computational age of the A1 layer was 46.511‒47.325 ka B P, whereas that of the A2 layer was 41.977‒42.167 ka B P. Although the number of artefacts within the Holocene sediments (>5 ka B P) overlying the late Pleistocene strata is limited, the characteristics of inheritance and development are still evident in the types of artefacts. The discovery presented in this study has completely updated and extended the connotation of Xiqiaoshan National Geopark and "Xiqiaoshan culture,"breaking through the late Pleistocene Paleolithic remains records with exact dating in the Pearl River Delta region for the first time. Therefore, a ground-breaking discovery can accurately trace the footsteps of modern humans in the coastal areas of South China from 40‒50 ka. It also reveals the rich features of lithic industry and the developmental characteristics and evolution of its cultural connotations during this period. The present study shows that during the relatively warm and humid conditions of marine isotope stages 3 (MIS3) interglacial period and the subsequent cold and arid stage of MIS2, human population in the Fuxian locality encountered environmental challenges and adopted new subsistence strategy, which is of great significance for understanding modern human responses and adaptations to global and regional environmental and climate change.

With the intensification of global climate change, floods caused by typhoons and heavy rainfall occur frequently. It is important to effectively identify flood events within sedimentary records to study the flood frequency patterns. Currently, grain size analysis is the commonly applied method for flood event identification. The hydrodynamic conditions and sediment sources identified from the grain size parameters are used to distinguish flood events. However, identification results from a single index can easily lead to inaccuracies due to complex river sedimentation processes. Therefore, it is necessary to select the most suitable proxy and, in combination with the implications of different types of indicators, identify flood events in study areas. In addition to grain size analysis, the technology of environmental magnetism has been widely applied in the sedimentology research of flood sediments owing to its advantages of sensitivity, rapidity, economy, and non-destructiveness. In this study, a longitudinal floodplain sediment profile collected from a small watershed in northern Guangdong was selected as the research object. Both grain size and magnetic characteristics of the entire profile were determined in detail. Based on the flood event records identified by sediment grain size characteristics, an in-depth analysis of the magnetic characteristic differences between the flood sedimentary layers and normal sedimentary layers, was performed. We aimed to establish a set of suitable magnetic parameters for identifying flood events in this region. Consequently, a new approach can be used to identify paleofloods within sedimentary records. The results indicate the following. 1) The sediment particle size composition is primarily composed of silt, which accounts for more than 70% of the total. Moreover, the sediment particle size tended to become finer from the flood sedimentary layer to the normal sedimentary layer. Three sublayers characterized by relatively high peak values of sand content and mean grain diameter were identified as flood event sediments within the flood sedimentary layer. 2) The composition and sources of magnetic minerals within the sediments from different sediment layers are similar. The predominant magnetite and some hematite within the sediments are from the natural weathering of parent materials within the watershed. Exogenous input from the tailings pond of the Dabaoshan mine is another source of magnetic particles. 3) As deposition is dominated by suspended sedimentation in the study area, sediment sorting is sufficient under the influence of a continuous long-term high-water level. As a result, the magnetic particles within the flood sedimentary layer are relatively fine. With the enhancement of hydrodynamic conditions, the grain size of the magnetic particles and the concentration of fine-grained magnetite and hematite became coarser and increased in the three identified flood event sublayers within the flood sedimentary layer (from the middle to the top of the sedimentary profile). Therefore, a combination of environmental magnetic parameters and magnetic mineral composition analysis can be used for the accurate identification of flood events recorded by sediments. In the study area, the magnetic characteristics of the relatively high contributions of fine-grained magnetite and hematite and the relatively low contribution of coarser magnetite to saturation isothermal remanent magnetization can be regarded as proxies for identifying flood events and strong hydrodynamic conditions.

The Cuo E (CE) core contains the entire Quaternary stratigraphy of the CE Lake (31°24′–31°.32′ N, 91°28′–91°33′E, Tibetan Plateau, China). Here, we study the magnetic properties of 1,748 samples from the CE core, combined with scanning electron microscopy and X‐ray energy dispersive spectrometer analysis on selected samples. The main magnetic minerals appear to be magnetite and greigite. To further quantify the presence of greigite in CE core, 84 samples were analyzed using rock magnetism in more detail including: susceptibility (χ) versus temperature, coercivity component analysis of acquisition curves of the isothermal remanent magnetization (IRM), and principal component analysis of the first‐order reversal curve (FORC) diagrams. The greigite content and saturation IRM over susceptibility (SIRM/χ) appear to be exponentially related. SIRM/χ can be used as greigite concentration indicator. We also propose a rapid way to identify greigite in the CE core: When SIRM/χ increases and anhysteretic remanent susceptibility (χARM) increases only slowly, the sample contains greigite. Samples with SIRM/χ < 15 kA/m also follow this relation. This greigite detection method has a lower limit of detection than the traditionally used SIRM/χ parameter. It is also faster than FORC analysis and thus particularly suitable for analysis of large sample collections. Twenty greigite‐bearing layers were identified in the CE core using this method. The location of the Jaramillo subchron in the CE core is controversial in the currently available magnetostratigraphy, possibly related to the presence of greigite in this core interval. Plain Language Summary: Paleomagnetic chronology is an important geological dating tool for sediment cores or sections that span sufficient duration, and one of its prerequisites is the identification of magnetic minerals. Greigite (Fe3S4) is a magnetic mineral that acquires its natural remanent magnetization at any time during diagenesis, so its presence has bearing on the accuracy of magnetic stratigraphy. In this work, we used rock magnetic methods to identify magnetite (Fe3O4) and greigite as the main magnetic minerals in the CE core on the Qinghai Tibet Plateau (China). We also semi‐quantitatively express the greigite amount and propose a rapid greigite identification method. This method is faster and simpler than other rock magnetic methods and thus particularly suitable for analysis of large sample collections. The approach also provides a framework for research into greigite and magnetic stratigraphy. Key Points: A rapid method to identify greigite is proposed, which is also applicable to samples with low SIRM/χSIRM/χ can be used as greigite concentration indicator and not only to indicate greigite above a certain thresholdTwenty layers of greigite were identified in the Cuo E core, which may be the cause of its inaccurate magnetic stratigraphy [ABSTRACT FROM AUTHOR]

In this research, we demonstrate an optical frequency comb (OFC) based on a figure-9 laser and polarization-maintaining fibers to measure the dispersion of a microcavity. We adopt a multi-branch structure to obtain a broadband spectrum from 1,250 nm to 1,640 nm with 6-dB bandwidth. The single-mode power at each wavelength of the supercontinuum spectra is greater than 300 nJ, which assures the signal-to-noise ratio of the beat notes between the OFC and the diode laser. The frequency stability of the repetition rate is about 7.5 × 10–14 in an integration time of 1 s. This system allows us to extend the measurement bandwidth to 60 THz at the sub-megahertz resolution, which meets the requirements of the microcavity’s higher-order dispersion measurement.

To address the issue of electronic equipment failure inside the instrument compartment due to aerodynamic heating during high-speed flight. Combining the heat transfer characteristics of phase change materials, a new instrument compartment structure was proposed as the research subject based on phase change materials. While studying the heat transfer characteristics of this structure, one-dimensional phase change heat transfer theoretical model was constructed based on the Lightfoot integral equation method, and the corresponding analytical solution was obtained. To explore the temperature change law of the instrument compartment structure and verify the rationality of the theoretical model, the new thermal experiment was carried out for the instrument compartment structure. Compared with the aluminum alloy instrument compartment structure, the experimental results show that the instrument compartment structure design based on phase change materials could effectively reduce the temperature of the structure itself, and the experimental data are in good agreement with the theoretical calculation results, which verified the rationality of the theoretical model and provided a scientific basis for the practical application of phase change materials in instrument compartment structures. [ABSTRACT FROM AUTHOR]