Evolution and modification of lithospheric mantle within deeply continental subduction zone: Insights from two contrasting orogenic garnet peridotites in South Altun–North Qaidam belt

Deciphering the geodynamic evolution and compositions of the Earth's mantle is crucial for understanding the origin and evolution of the Earth, however, the original geodynamic setting and significance of tectonically emplaced mantle in ancient orogens is always ambiguous. Orogenic garnet peridotites can shed light on the understanding of upper mantle petrology and the tectonic processes that operate at convergent plate boundaries. Petrographical evidence and P-T conditions of two contrasting types of orogenic garnet peridotites in the South Altun–North Qaidam (SAT–NQD) HP/UHP metamorphic belt suggest that they experienced a notably different geological history. Geochemical characteristics show that the garnet peridotites in the Bashiwake unit represent ultramafic complexes emplaced into the continental crust before subduction, while those in the Luliangshan unit originate from the mantle wedge above a deep subduction zone. Sr[sbnd]Nd isotopes for the two contrasting ultramafic rocks indicate that both have been modified either by mantle metasomatism or crustal contamination. The distinct petrochemical and isotopic characteristics of these contrasting orogenic garnet peridotite types demonstrate spatio-temporal variation in the tectonothermal-evolution of the SAT–NQD HP/UHP orogen

Normative Analysis of Individual Brain Differences Based on a Population MRI-Based Atlas of Cynomolgus Macaques

The developmental trajectory of the primate brain varies substantially with aging across subjects. However, this ubiquitous variability between individuals in brain structure is difficult to quantify and has thus essentially been ignored. Based on a large-scale structural magnetic resonance imaging dataset acquired from 162 cynomolgus macaques, we create a species-specific 3D template atlas of the macaque brain, and deploy normative modeling to characterize individual variations of cortical thickness (CT) and regional gray matter volume (GMV). We observed an overall decrease in total GMV and mean CT, and an increase in white matter volume from juvenile to early adult. Specifically, CT and regional GMV were greater in prefrontal and temporal cortices relative to early unimodal areas. Age-dependent trajectories of thickness and volume for each cortical region revealed an increase in the medial temporal lobe, and decreases in all other regions. A low percentage of highly individualized deviations of CT and GMV were identified (0.0021%, 0.0043%, respectively, P \u3c 0.05, false discovery rate [FDR]-corrected). Our approach provides a natural framework to parse individual neuroanatomical differences for use as a reference standard in macaque brain research, potentially enabling inferences regarding the degree to which behavioral or symptomatic variables map onto brain structure in future disease studies

Synthesis and characterization of TiO{208} based nanomaterials

Systematically synthesized one-dimensional (1D) nanomaterials - nanotubes (NTs), nanofibers (NFs) and nanoribbons (NRs) - based on TiO2 were characterized using thermal analysis, Energy-dispersive X-ray Spectroscopy(EDS), X-ray Photoelectron Spectroscopy (XPS) analysis, X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) techniques. Effects of different starting materials, temperature and other reaction parameters on the formation of various nanostructures were examined. Crystalline TiO2 precursor treated in alkali solution results in NTs and amorphous precursor produces NFs at lower temperature (100-180°C) while twinned NRs are generally produced at higher temperature (>180°C). EDS, XRD and electron diffraction (ED) results suggested the coexistence of anatase and an orthorhombic titanate AxTi2-x/4 Πx/4O4 (A: H+ or Na+, x≈ 0.7, Π: vacancy) phase in all three 1D nanoproducts. High-resolution TEM evidences and image simulation confirmed that the formation of TiO2-based nanostructures was driven by 45° anatase-titanate quasi-twins, which formed the building blocks of NTs, NFs and NRs. The structure of NR was investigated relying on the series of ED patterns obtained by tilting the NR along its long-axis. The ED pattern series was consistent with the one predicted by the proposed model. By electron irradiation in TEM, a cubic TiO phase was discovered in NTs and NRs. XPS analysis suggests the existence of reduced state of Titanium in the sample while high temperature and high vacuum environment of TEM preserves the Ti-rich phase leading to the formation of TiO structure

Electrochemical Lithium Extraction with Gas Flushing of Porous Electrodes

Electrochemical extraction of lithium from seawater/brine is receiving more and more attention because of its environment-friendly and energy-saving features. In this work, an electrochemical lithium extraction system with gas flushing of porous electrodes is proposed. We verified that the operation of multiple gas washes can significantly reduce the consumption of ultrapure water during the solution exchange and save the time required for the continuous running of the system. The water consumption of multiple gas flush operations is only 1/60 of that of a normal single flush to obtain a purity close to 100% in the recovery solution. By comparing the ion concentration distribution on the electrode surface in flow-through and flow-by-flow modes, we demonstrate that the flow-through mode performs better. We also verified the lithium extraction performance of the whole system, achieving a purity close to 100% and average energy consumption of 0.732 kWh∙kg−1 in each cycle from the source solution of the simulated Atacama salt lake water. These results provide a feasible approach for the large-scale operation of electrochemical lithium extraction from seawater/brine

Digital Integration of LiDAR System Implemented in a Low-Cost FPGA

With the development of artificial intelligence, LiDAR finds significant applications in robotics and autonomous driving. Aiming at increasing the compactness and the integration of 2-D LiDAR, this paper presents a highly digitally integrated 2-D LiDAR system implemented in a low-cost FPGA. The system is made of off-the-shelf components to limit the cost to USD 100. A laser transceiver with a symmetrical transmitting and receiving lens emits and collects laser pulses to range distance using the time-of-flight (ToF) method. As a key component in ToF, the FPGA-based time-to-digital converter (TDC) is adopted for counting the round-trip time of pulses, which is implemented in a low-cost FPGA of ZYNQ7010 with limited resources. The symmetrical structure of the delay line is used to design a more efficient TDC. The FPGA-TDC enables flexibility of design and integration with more functional logics and is microcontroller-free. All the digital logics including data processing and controlling are integrated into an FPGA with the TDC logics to realize fully digital integration and compact dimensions. The utilization of the whole architecture in the FPGA is about 15%. The experimental results demonstrated that the ranging accuracy of the LiDAR is about 2 cm, which is suitable for consumer electronics

Supplemental Material: Diachronous subduction, closure of the Proto-Tethys Ocean, and collisional accretion of microcontinents: Insights from the early Paleozoic intermediate-mafic rocks in the Amdo microcontinent of the Tibetan Plateau

Table S1: Summary of age data for the Ediacaran–early Paleozoic magmatic rocks in the East Asian blocks along the northern margin of East Gondwana. Table S2: LA-ICP-MS zircon U-Pb dating results for the igneous rocks from the Amdo microcontinent, central Tibet. Table S3: Hf isotopic data of zircons for the intermediate-mafic rocks from the Amdo microcontinent, central Tibet. Table S4: Whole-rock Sr-Nd isotopic compositions of the meta-basites from the Amdo microcontinent, central Tibet. Table S5: Major- and trace-element compositions of the intermediate-mafic rocks from the Amdo microcontinent, central Tibet. Figure S1: TiO2 (wt%) vs. Th/NbPM, showing partial melting of spinel peridotite source with assimilation of crustal melts.</p

<em>c</em>. 1.85 Ga HP granulite-facies metamorphism in the Dunhuang block of the Tarim Craton, NW China: evidence from U–Pb zircon dating of mafic granulites

<p>Mafic granulites of the Dunhuang block, eastern Tarim Craton, record high-pressure granulite-facies metamorphism followed by a medium- to low-pressure granulite-facies metamorphic overprint, suggesting a clockwise <em>P–T</em> path and implying an environment of collisional orogenesis. Zircon U–Pb ages of two samples are 1834 ± 12 Ma and 1842 ± 5 Ma. Mineral inclusions in zircon indicate that these ages record the high-pressure granulite-facies event, suggesting that the Tarim Craton may be related to the <em>c</em>. 1.85 Ga assembly of the Columbia supercontinent. Similar <em>c</em>. 1.85 Ga metamorphism in both the Dunhuang block and the Alxa block of the North China Craton supports their correlation across the Altyn Tagh fault. </p

Combined Rutile–zircon Thermometry and U-Pb Geochronology: New Constraints on Early Paleozoic HP/UHT Granulite in the South Altyn Tagh, North Tibet, China

HP granulite and garnet peridotite constitute a HP metamorphic unit in the south Altyn Tagh, northern Tibet. Previous data suggest that HP granulites experienced high pressure, ultrahigh-temperature metamorphism (870–1050 °C, 19–25 kbar), followed by a medium pressure granulite facies overprint (780–820 °C, 9.5–12 kbar). Previous zircon U–Pb geochronology of HP granulites gave an age of ca. 500 Ma, but it is unclear if this age reflects the metamorphic peak, or the post-peak overprint. In this contribution, new SHRIMP analyses indicate that the zircons associated with the peak metamorphic assemblage in HP felsic granulite are characterized by flat heavy REE patterns and 30–62 ppm Ti, yielding a temperature of 892–1002 °C by Ti-in-zircon thermometry, suggesting that the growth of the zircons occurred under or close to peak ultrahigh-temperature conditions rather than under post-peak conditions. These zircons gave a SHRIMP U–Pb age of 495 ± 4 Ma, representing the age of peak metamorphism. In contrast, oscillatory zoned zircon cores yield magmatic REE patterns, Ti-in-zircon temperatures of 720-820 °C, and Neoproterozoic U–Pb ages (936 ± 22 Ma). This indicates that the protoliths of the felsic granulites were formed in the early Neoproterozoic and were taken to extreme temperatures and pressures during the early Paleozoic orogenic event. In situ LA-ICPMS and EMP analyses indicate that rutiles are characterized by broad scatter and bimodal distribution in both Zr concentration and U–Pb age, which are interpreted as a result of recrystallization or growth rather than volume diffusion. The first rutile U–Pb age cluster is at ca. 485 Ma with a Zr concentration of ca. 3000 ppm, yielding ca. 950 °C at 20 kbar, implying that they grew at or near the peak metamorphic conditions. The second rutile U–Pb age cluster is at ca. 450 Ma with a Zr concentration of ca. 1000 ppm, corresponding to a temperature around 780 °C at 10 kbar, which is related to post-peak reheating under medium pressure/medium temperature granulite facies conditions. These results demonstrate that HP granulites in the south Altyn Tagh experienced a peak ultrahigh temperature and high pressure metamorphism at ca. 495 Ma, followed by medium pressure/medium temperature granulite facies overprint before ca. 450 Ma

Experimental and Numerical Study of Stagnant Zones in Pebble Bed

The experimental method (side area method) and DEM simulation have been carried out to analyse the stagnant zone in the quasi-two-dimensional silos. The side area method is a phenomenological method by means of investigating the interface features of different areas composed of different coloured pebbles. Two methods have been discussed to define the stagnant zone. In particular, the area of the stagnant zone has been calculated with the mean-streamline method, and the tracking time of different marking pebbles has been investigated with the stagnant time method to explore the kinematics characteristics of the pebbles. The stagnant zone is crucial for the safety of the pebble-bed reactor, and the practical reactor core must avoid the existence of the stagnant zone. Furthermore, this paper also analyses the effects of bed configuration (the bed height, the base angle, and the friction coefficient) on stagnant zone with the two methods mentioned above. In detail, the bed height shows little impact on the stagnant zones when the bed height exceeds a certain limit, while the base angle has negative prominent correlation with the stagnant zone. The friction coefficient effect seems complicated and presents the great nonlinearity, which deserves to be deeply investigated