Evaluation of boron isotopes in halite as an indicator of the salinity of Qarhan paleolake water in the eastern Qaidam Basin, western China

In this study, nineteen brine samples from the Qarhan Salt Lake(QSL) in western China were collected and analyzed for boron(B) and chlorine(Cl) concentrations, total dissolved solids(TDS), pH values and stable B isotopic compositions. The B concentrations and δ^(11) B values of brines in the QSL range from 51.6 mg/L to138.4 mg/L, and from +9.32& to +13.08&, respectively. By comparison of B concentrations and TDS of brines in QSL with evaporation paths of brackish water, we found that B enrichment of brines primarily results from strong evaporation and concentration of Qarhan lake water. Combining with comparisons of B concentrations, TDS, p H values and δ^(11) B values of brines, previously elemental ratios(K/Cl, Mg/Cl, Ca/Cl, B/Cl) and δ^(11) B values of halite from a sediment core(ISL1 A), we observe good correlations between B concentrations and TDS, TDS and pH values, pH and δ^(11) B values of brines, which demonstrate that higher B concentrations and more positive δ^(11) B values of halite indicate higher salinity of the Qarhan paleolake water as well as drier paleoclimatic conditions. Based on this interpretation of the δ^(11) B values of halite in core ISL1 A, higher salinity of the Qarhan paleolake occurred during two intervals, around 46-34 ka and26-9 ka, which are almost coincident with the upper and lower halite-dominated salt layers in core ISL1 A,drier climate phases documented from the δ^(18) O record of carbonate in core ISL1 A and the paleomoisture record in monsoonal central Asia, and a higher solar insolation at 30°N. These results demonstrate that the δ^(11) B values of halite in the arid Qaidam Basin could be regarded as a new proxy for reconstructing the salinity record of paleolake water as well as paleoclimate conditions.

Characterization of the retinal vasculature in fundus photos using the PanOptic iExaminer system

Background:The goal was to characterize retinal vasculature by quantitative analysis of arteriole-to-venule(AM)ratio and vessel density in fundus photos taken with the PanOptic iExaminer System.Methods:The PanOptic ophthalmoscope equipped with a smartphone was used to acquire fundus photos centered on the optic nerve head.Two fundus photos of a total of 19 eyes from 10 subjects were imaged.Retinal vessels were analyzed to obtain the AN ratio.In addition,the vessel tree was extracted using deep learning U-NET,and vessel density was processed by the percentage of pixels within vessels over the entire image.Results:All images were successfully processed for the AN ratio and vessel density.There was no significant difference of averaged AN ratio between the first(0.77±0.09)and second(0.77±0.10)measurements(P=0.53).There was no significant difference of averaged vessel density(%)between the first(6.11±1.39)and second(6.12±1.40)measurements(P=0.85).Conclusions:Quantitative analysis of the retinal vasculature was feasible in fundus photos taken using the PanOptic ophthalmoscope.The device appears to provide sufficient image quality for analyzing AN ratio and vessel density with the benefit of portability,easy data transferring,and low cost of the device,which could be used for pre-clinical screening of systemic,cerebral and ocular diseases.

Fungal spore record of pastoralism on the NE Qinghai-Tibetan Plateau since the middle Holocene

Pastoralism is considered a crucial factor in the eventual year-round occupation of high-altitude regions(>3000 m asl)of the Qinghai-Tibetan Plateau,and the northeastern Qinghai-Tibetan Plateau(NE-QTP)was an important corridor for early human occupation.We analyzed fossil fungal spore records for the last 8500 years from a high resolution aeolian section at Langgeri(LGR)on the NE-QTP.Thirty-two fungal spore types were identified in the LGR section,including seven coprophilous types.We combined analysis of coprophilous fungal spores,Cyperaceae,Artemisia,and Hippophae pollen,and the charcoal>50µm fraction to explore the timing and controls of pastoralism on the NE-QTP since the middle Holocene.Pastoralism commenced at LGR shortly before ca.5.5 ka and gradually increased between ca.5.5–3.5 ka,but markedly intensified after ca.2.2 ka,with three periods of growth at ca.2.1–1.9,1.4–1.2,and 0.6–0 ka,and a decline at ca.1.1–0.6 ka.The timing of changes in pastoral activity on the NE-QTP based on the coprophilous fungal spore record is supported by regional archeology and historical documents.Technological and political developments,rather than climate change,played key roles in the long-term fluctuations of regional pastoralism on the NE-QTP in the late Holocene.

Optical and scintillation properties of Bi_4Si_3O_(12):RE(RE=Eu^(3+), Sm^(3+),Ho^(3+), Tb^(3+))single crystals

Bi_4 Si_3 O_(12):RE(BSO:RE, RE = Eu^(3+), Sm^(3+), Ho^(3+), Tb^(3+)) crystals were grown by the modified vertical Bridgeman method, and doping effects on scintillation properties were investigated. Under γ-ray irradiation, the light yield of BSO doped with small doses of Eu^(3+) increases slightly, and the energy resolution improves significantly compared to pure BSO, therefore the ability of distinguishing between particles will be improved for BSO crystals with a small amount of Eu^(3+) dopant. The results show that a small amount of Eu^(3+) doping can sensitize the Bi^(3+) ions. The sensitization effect enables the reduction of intrinsic defects, and thus improves the scintillation properties. However, the relative light yield of BSO:Tb(1.0 mol%) crystal is 4.3%, which is smaller than 5.0% of pure BSO. The improved light yield and energy resolution in the BSO:Eu and BSO:Sm crystals are considered an impressive achievement in the optimization of this scintillator which is already suitable for applications such as dual-readout calorimeters and homogeneous hadron calorimeters.

Characterization of the retinal vasculature in fundus photos using the PanOptic iExaminer system

Background:The goal was to characterize retinal vasculature by quantitative analysis of arteriole-to-venule(A/V)ratio and vessel density in fundus photos taken with the PanOptic iExaminer System.Methods:The PanOptic ophthalmoscope equipped with a smartphone was used to acquire fundus photos centered on the optic nerve head.Two fundus photos of a total of 19 eyes from 10 subjects were imaged.Retinal vessels were analyzed to obtain the A/V ratio.In addition,the vessel tree was extracted using deep learning U-NET,and vessel density was processed by the percentage of pixels within vessels over the entire image.Results:All images were successfully processed for the A/V ratio and vessel density.There was no significant difference of averaged A/V ratio between the first(0.77±0.09)and second(0.77±0.10)measurements(P=0.53).There was no significant difference of averaged vessel density(%)between the first(6.11±1.39)and second(6.12±1.40)measurements(P=0.85).Conclusions:Quantitative analysis of the retinal vasculature was feasible in fundus photos taken using the PanOptic ophthalmoscope.The device appears to provide sufficient image quality for analyzing A/V ratio and vessel density with the benefit of portability,easy data transferring,and low cost of the device,which could be used for pre-clinical screening of systemic,cerebral and ocular diseases.