Arid northwestern China is considered to be a major source of atmospheric dust supply to the Northern Hemisphere. However, dust storm evolution and dust emission processes in the past remain unclear due to the scarcity of geologic archives in this region. Hydrologically closed lakes in dust source areas act as a trap, providing the opportunity to trace the history of dust emission or eolian activity. Here we present the results of dust storm proxies and a dust storm history from Lake Sugan in the Qaidam Basin, a dust source area, on the northern Qinghai‐Tibetan Plateau. Grain size analyses of the materials deposited during modern dust storms and of the lake surface sediments demonstrate that the coarse component of the lake sediments was transported primarily by ambient winds when dust storms occurred. In combination with a sediment chronology generated by counting annual laminations, a 2000‐year dust storm history was reconstructed on the basis of changes in the coarse component and magnetic susceptibility of the lake sediments. Frequent and/or intensive dust storms occurred during the intervals AD 300–500, AD 1180–1240, and AD 1500–1700. The occurrence of dust storms largely coincided with the strengthening of the Siberian High with colder air masses from high latitudes, such as during the Little Ice Age, frequently encroaching into the dust source areas in northwestern China. Our results suggest that wind strength plays an important role in dust emissions in arid source areas. However, dust storms in the late 20th century are most likely associated with disturbance of the ground surface caused by petroleum exploitation in the Qaidam Basin.

All-inorganic perovskite (CsPbX 3 , X = Cl, Br, I) nanorods (NRs) not only retain their inherent advantages such as a high photoluminescence quantum yield and broad wavelength tunability but also exhibit superior photophysical properties including their extremely strong multiphoton absorption (MPA). However, the spectral dynamics and MPA properties of CsPbX 3 NRs have not been fully investigated. Here, we report comprehensive comparison studies on the femtosecond spectral dynamical properties of CsPb(Br 0.8 Cl 0.2 ) 3 , CsPbBr 3 , and CsPb(Br 0.85 I 0.15 ) 3 NRs, including their influences on their hot-carrier cooling, biexciton lifetime, and biexciton binding energy. Interestingly, although the three kinds of perovskite NRs have similar diameters and lengths, they differ significantly in their nonlinear optical properties, among which the CsPb(Br 0.85 I 0.15 ) 3 displayed the greatest MPA cross sections. Furthermore, the multiphotonexcited stimulated emission of CsPb(Br 0.8 Cl 0.2 ) 3 and CsPbBr 3 NRs is demonstrated. This work indicates that CsPbX 3 (X = Cl, Br, I) NRs are excellent candidates for exploring their applications in different optoelectronic devices.

Emerging CsPbX 3 (X ¼ Cl, Br, and I) perovskite nanocrystals (NCs) have been demonstrated to be efficient emitters with a high fluorescence quantum yield, making these materials interesting for optical applications as well as for fundamental physics. Interestingly, doping with transition metal ions has been extensively explored as a way of introducing new optical, electronic, and magnetic properties, making perovskite NCs much more functional than their undoped counterparts. However, there have been no reports regarding the nonlinear optical properties of transition metal ion doped perovskite NCs. Herein, by using femtosecond-transient absorption spectroscopy, we have determined the one-photon linear absorption cross-section ($1.42 Â 10 À14 cm 2) of Mn-doped CsPbCl 3 NCs ($11.7 6 1.8 nm size, $0.2% doping concentration, and $600 nm emission wavelength). More importantly, their nonlinear optical properties-in particular, the two-photon absorption (TPA) and resultant emission-were investigated. Notably, the NCs exhibit wavelength-dependent TPA with a maximum value up to $3.18 Â 10 5 GM at a wavelength of 720 nm. Our results indicate that Mn-doped CsPbCl 3 NCs show promise in nonlinear optical devices and multiphoton fluorescence lifetime imaging.

All‐inorganic perovskite nanocrystals (NCs) have attracted considerable attention due to their extensive photonic and optoelectronic properties. These NCs are shown to exhibit strong multiphoton absorption (MPA). However, studies on the MPA properties of perovskite NCs are only conducted on weakly confined perovskite cubic NCs, while the relevant influences of the geometry are never discussed. To the best of knowledge, this report describes the first comparison of the MPA properties of CsPbBr3 2D nanoplates (2D NPs) and cubic NCs. Based on the experimental results, it can be concluded that stronger quantum confinement effect of 2D NPs will strongly enhance their MPA with outstanding normalized‐volume two‐ and three‐photon absorption cross sections up to 1561 GM nm−3 and 7.2 × 10−78 cm6 s2 photon−2 nm−3, respectively. This work demonstrates that CsPbBr3 2D NPs are good candidates for exploring the influences of quantum confinement on MPA properties of perovskite NCs, which are also highly suitable for the applications of multiphoton imaging and nonlinear optoelectronics.

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Keywords:Deep soil Land use MABE Temporal stability Most temporally stable depth The Chinese Loess Plateau s u m m a r y Deep soil-water content (SWC) plays a crucial role in water-limited terrestrial ecosystems, because plant roots can extract soil water from depths of 20 m or more. The distribution of soil water and its temporal variation in deep (>5 m) soil profiles are not completely understood, partly due to the time and labor needed for their determination. We examined the vertical distribution patterns and temporal stabilities of soil water in 21-m soil profiles for two years under four typical land use types in the Liudaogou watershed of the Chinese Loess Plateau (CLP). The SWCs exhibited considerable variability over both depth and time under farmland, natural grassland, planted grassland, and shrubland. The soil profile could be partitioned into an active layer (0-2 m) and a relatively stable layer (2-21 m) based on the amount of temporal change in SWC. The mean available soil water contents (AWCs) among the land use types in the depth-time domain differed significantly (P < 0.05), and followed the order: farmland (7.1%) > natural grassland (6.5%) > planted grassland (5.7%) > shrubland (4.9%). The mean available soil water storage for each 1-m-depth (AWS 1m ) in the 0-21 m profile, in the time domain, ranged from 50.3 to 71.4 mm among the four land use types. Within the 21-m profile, as the depths of sub-profiles increased from 3 m to 21 m, the most temporally stable depths (MTSDs) of AWS 1m tended to become deeper in a step-like manner, producing ranges of MTSDs of 3-18 m, 2-15 m, 2-9 m, and 3-20 m under farmland, natural grassland, planted grassland, and shrubland, respectively. The ability of the MTSDs to estimate the mean AWS 1m in a soil profile was generally acceptable for each sub-profile, as indicated by the RMSD and RBIAS values obtained from a validation dataset, which ranged from 3.6 to 7.7 mm and from 0.07 to 0.13, respectively, among the four land use types. The mean AWS 1m within the 21-m profile could, in general, be accurately estimated by measuring AWC to a depth of only 18 m based on the temporal stability analysis. Land use greatly affected the vertical distributions and temporal stabilities of the AWC in the deep soils. The knowledge obtained from this information is vital for the sustainable use of water resources, rational management of various land uses, and scientific determinations of soil water in deep soils on the CLP and possibly in other fragile ecosystems covered by deep soils around the world.

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