Cyclic formation and stabilization of Archean lithosphere by accretionary orogenesis : constraints from TTG and potassic granitoids, North China Craton

This study is financially supported by the National Natural Science Foundation of China (Grant Nos. 41502179, 41530207, 41472165) and Central University Basic Scientific Research Business Expenses of China University of Geosciences (Beijing) (Grant No. 2652015038). PAC acknowledges support from Australian Research Council grant FL160100168.Accretionary orogens are major sites of modern continental growth, yet their role in the development of Archean continental crust remains enigmatic. Diverse granitoid suites from tonalite-trondhjemite-granodiorite (TTG) to potassic granitoids appeared during late Archean, representing a period of major continental formation and stabilization. In this study, whole-rock geochemical and zircon U-Pb and Lu-Hf isotopic data are reported for Neoarchean granitoid gneisses from the Northern Liaoning Terrane, northeastern North China Craton (NCC). Older granitoid gneisses (~2592-2537 Ma) define three magmatic zones migrating from southeast to northwest, each showing a common magmatic evolution from high-pressure TTGs to medium-/low-pressure TTGs and potassic granitoids. They have depleted zircon ƐHf(t) of +0.5 to +8.7. Younger ~2529-2503 Ma potassic granitoids and TTGs occur throughout the terrane, which are marked by variable zircon ƐHf(t) of -4.7 to +8.1, and are coeval with regional high grade metamorphism. Petrogenetic modeling and changing Sr/Y and (La/Yb)N of the granitoids suggest that the crust experienced episodic thickening and thinning, and became progressively evolved through development of potassic granitoids and sedimentary successions. The metavolcanic basement to the granitoids display tholeiitic to calc-alkaline affinities, together with the top-to-the-northwest thrusting and associated VMS-type Cu-Zn deposits, suggesting cyclic crustal formation of Northern Liaoning within an accretionary orogen with a SE-dipping subduction polarity. Cyclic crustal thickening and thinning is related to tectonic switching from advancing to retreating relations between the downgoing and overriding plate. After ~2530 Ma, this accretionary system accreted to the ancient continental nucleus of NCC (Anshan-Benxi Terrane), signifying final lithosphere stabilization.Publisher PDFPeer reviewe

Late Neoarchean subduction-related crustal growth in the Northern Liaoning region of the North China Craton : evidence from ∼2.55-2.50 Ga granitoid gneisses

This study is financially supported by the National Natural Science Foundation of China (Grant Nos. 41272209, 41472165, 41502179, 41530207) and the Central University Basic Scientific Research Business Expenses of China University of Geosciences (Beijing) (Grant No. 2652015038).The North China Craton (NCC), dominated by ∼2.6-2.5 Ga tectonothermal events, provides a natural laboratory to study Neoarchean crustal growth and geodynamic evolution. Late Neoarchean granitoid gneisses are well exposed in the Northern Liaoning Province, located north of the ancient Anshan-Benxi terrane along the northeastern margin of the Eastern Block (EB) of the NCC. LA-ICPMS zircon U-Pb isotopic dating reveal that granitoid gneisses in the Qingyuan area can be grouped into two major episodes, i.e., ∼2559-2534 Ma strongly gneissic quartz dioritic and tonalitic to trondhjemitic gneisses; and ∼2529-2495 Ma weakly gneissic to massive quartz monzodioritic and monzogranitic gneisses, with subordinate tonalitic to trondhjemitic gneisses. The late magmatic episode was accompanied by regionally high-grade metamorphism (∼2510-2495 Ma). Most granitoid gneisses display highly depleted zircon εHf(t2) values (+4.2-+8.1), whereas one monzogranitic gneiss shows negative values of -4.7 to -1.0, indicating late Neoarchean crustal growth with minor involvement of ancient continental materials probably sourced from the Anshan-Benxi terrane. Geochemical and petrogenetic studies reveal that the quartz dioritic magmas were derived from partial melting of plagioclase-poor garnet amphibolites or eclogites metamorphosed from oceanic slab materials, with slab melts contaminated by mantle wedge peridotites during ascent. The tonalitic to trondhjemitic magmas stemmed from partial melting of mainly juvenile metabasaltic rocks with minor metagreywackes of lower arc crust. In comparison, the quartz monzodioritic and monzogranitic magmas were derived respectively from partial melting of depleted mantle sources metasomatized by slab-derived fluids and metagreywackes with different crustal resident ages at middle to lower crustal levels. Combined with previous studies of metavolcanic rocks, the Northern Liaoning Province records late Neoarchean crustal growth, evolving from mid-ocean ridge, through initiation and maturation of an intra-oceanic arc, to arc-continent collision. Arc-continent accretion and possibly slab rollback processes may have triggered reworking of both juvenile arc crust and minor ancient continental margin materials, generating the magmatic precursors for the monzogranitic gneisses. Overall, the intense late Neoarchean crustal growth of the EB was controlled mainly by arc-continent accretion, possibly linked to global assembly of cratonic fragments.PostprintPeer reviewe

Deep Learning Guided Autonomous Retinal Surgery using a Robotic Arm, Microscopy, and iOCT Imaging

Recent technological advancements in retinal surgery has led to the modern operating room consisting of a surgical robot, microscope, and intraoperative optical coherence tomography (iOCT). The integration of these tools raises the fundamental question of how to effectively combine them to enable surgical autonomy. In this work, we address this question by developing a unified framework that enables real-time autonomous surgical workflows utilizing the aforementioned devices. To achieve this, we make the following contributions: (1) we develop a novel imaging system that integrates microscopy and iOCT in real-time, accomplished by dynamically tracking the surgical instrument via a small iOCT scanning region (e.g. B-scan), which was not previously possible; (2) implementing various convolutional neural networks (CNN) that automatically segment and detect task-relevant information for surgical autonomy; (3) enabling surgeons to intuitively select goal waypoints within both the microscope and iOCT views through simple mouse-click interactions; (4) integrating model predictive control (MPC) for real-time trajectory generation that respects kinematic constraints to ensure patient safety. We show the utility of our system by tackling subretinal injection (SI), a challenging procedure that involves inserting a microneedle below the retinal tissue for targeted drug delivery, a task surgeons find challenging due to requiring tens-of-micrometers of accuracy and precise depth perception. We validate our system by conducting 30 successful SI trials on pig eyes, achieving needle insertion accuracy of $26 \pm 12 \mu m$ to various subretinal goals and duration of $55 \pm 10.8$ seconds. Preliminary comparisons to a human operator performing SI in robot-assisted mode highlight the enhanced safety of our system.Comment: pending submission to a journa

The origin of human pathogenicity and biological interactions in Chaetothyriales

Fungi in the order Chaetothyriales are renowned for their ability to cause human infections. Nevertheless, they are not regarded as primary pathogens, but rather as opportunists with a natural habitat in the environment. Extremotolerance is a major trend in the order, but quite diferent from black yeasts in Capnodiales which focus on endurance, an important additional parameter is advancing toxin management. In the ancestral ecology of rock colonization, the association with metabolite-producing lichens is signifcant. Ant-association, dealing with pheromones and repellents, is another mainstay in the order. The phylogenetically derived family, Herpotrichiellaceae, shows dual ecology in monoaromatic hydrocarbon assimilation and the ability to cause disease in humans and cold-blooded vertebrates. In this study, data on ecology, phylogeny, and genomics were collected and analyzed in order to support this hypothesis on the evolutionary route of the species of Chaetothyriales. Comparing the ribosomal tree with that of enzymes involved in toluene degradation, a signifcant expansion of cytochromes is observed and the toluene catabolism is found to be complete in some of the Herpotrichiellaceae. This might enhance human systemic infection. However, since most species have to be traumatically inoculated in order to cause disease, their invasive potential is categorized as opportunism. Only in chromoblastomycosis, true pathogenicity might be surmised. The criterion would be the possible escape of agents of vertebrate disease from the host, enabling dispersal of adapted genotypes to subsequent generations.info:eu-repo/semantics/publishedVersio

Morphological, Transcriptome, and Hormone Analysis of Dwarfism in Tetraploids of <i>Populus alba</i> × <i>P. glandulosa</i>

Breeding for dwarfism is an important approach to improve lodging resistance. Here, we performed comparative analysis of the phenotype, transcriptome, and hormone contents between diploids and tetraploids of poplar 84K (Populus alba × P. glandulosa). Compared with diploids, the indole-3-acetic acid (IAA) and gibberellin (GA3) contents were increased, whereas the jasmonic acid (JA) and abscisic acid (ABA) contents were decreased in tetraploids. RNA-sequencing revealed that differentially expressed genes (DEGs) in leaves of tetraploids were mainly involved in plant hormone pathways. Most DEGs associated with IAA and GA promotion of plant growth and development were downregulated, whereas most DEGs associated with ABA and JA promotion of plant senescence were upregulated. Weighted gene co-expression network analysis indicated that certain transcription factors may be involved in the regulation of genes involved in plant hormone pathways. Thus, the altered expression of some genes in the plant hormone pathways may lead to a reduction in IAA and GA contents, as well as an elevation in ABA and JA contents, resulting in the dwarfing of tetraploids. The results show that polyploidization is a complex biological process affected by multiple plant hormone signals, and it provides a foundation for further exploration of the mechanism of tetraploids dwarfing in forest trees

Mechanical Behavior and Energy Evolution of Sandstone considering Slenderness Ratio Effect

To study the influence of slenderness ratio effect on the mechanical behavior, acoustic emission properties, and energy evolution of sandstone, the uniaxial compression tests coupled with acoustic emission technology are carried out at different slenderness ratios D (0.5, 1.0, 1.5, 2.0, 3.0). The results show that a logarithmic function relationship is observed between the peak strength, the peak strain, and the elastic modulus with slenderness ratio. The failure patterns of the tested sandstone varied significantly with the increasing slenderness ratio. When the slenderness ratio, D, is lower than 1.5, complex failures and multiple shear planes are formed, while simple failures and single shear planes are generated at D larger than 1.5. Besides, the AE ringing counts are more obvious with a higher slenderness ratio, D, at the initial compression stage due to the greater body volume and more defects in the sandstone. The energy evolution curves and energy ratio distribution curves can be divided into four stages, corresponding to the stress-strain curves

Prediction of Stope Stability Using Variable Weight and Unascertained Measurement Technique

A new model is established to analyze mining stope stability, using variable weight theory to calculate the index weight for each factor in different stopes and unascertained measure evaluation technique to predict the risk grade of stope stability. In this model, an evaluation index system by virtue of the 7 most important factors is established, including rock saturated uniaxial compressive strength, rock quality designation, rock joint and fissure, stope span, condition of pillar, groundwater seepage volume, and rate of supporting pit roof. And each index is divided into 5 grades by assignment value and the classification method of standardization. Accordingly, the analysis result is also classified into 5 risk grades. This model is used for the 6 main stopes from the -270 m section in Xin-Qiao Mine, China. The results, giving risk grade for each stope and guiding the use of corresponding measures, avoided the problem of state out of balance caused by conventional invariable weight theory models and have ensured no accident occurred in mining production in recent years. This model can be used in other mines widely, by assigning values for the 7 factors on basis of current in situ cases

SIMULATIONAL AND EXPERIMENTAL STUDY ON THE CRITICAL FACTORS OF HIGH-SPEED BRAKING SQUEAL

Complex eigenvalue analysis using ABAQUS has been carried out,based on a simplified finite element model of high-speed disc brake system.The critical factors generating brake squeal have been computationally studied and verified by experiments.Simulation results show that,brake squeal more likely to occur under the conditions of low-speed,high pressure,negative μ-υ slope,and high coefficient of friction.The effects of sliding speed and normal contact pressure on the generation of brake squeal have been verified.This study will provide effective guidance in the prevention and control of brake squeal

Hierarchical Stochastic Optimal Scheduling of Electric Thermal Hydrogen Integrated Energy System Considering Electric Vehicles

After a large number of electric vehicles (EVs) are connected to the integrated energy system, disorderly charging and discharging of EVs will have a negative impact on the safe and stable operation of the system. In addition, EVs’ uncertain travel plans and the stochastic fluctuation of renewable energy output and load power will bring risks and challenges. In view of the above problems, this paper establishes a hierarchical stochastic optimal scheduling model of an electric thermal hydrogen integrated energy system (ETH-IES) considering the EVs vehicle-to-grid (V2G) mechanism. The EVs charging and discharging management layer aims to minimize the variance of the load curve and minimize the dissatisfaction of EV owners participating in V2G. The multi-objective sand cat swarm optimization (MSCSO) algorithm is used to solve the proposed model. On this basis, the daily stochastic economic scheduling of ETH-IES is carried out with the goal of minimizing the operation cost. The simulation results show that the proposed strategy can better achieve a win-win situation between EV owners and microgrid operators, and the operation cost of the proposed strategy is reduced by 16.55% compared with that under the disorderly charging and discharging strategy, which verifies the effectiveness of the proposed model and algorithm