Forming Giant Planets Around Late-M Dwarfs: Pebble Accretion and Planet-Planet Collision

We propose a pebble-driven core accretion scenario to explain the formation of giant planets around the late-M dwarfs of $M_{\star}{=}0.1{-}0.2 \ M_{\odot}$. In order to explore the optimal disk conditions for giant planet, we perform N-body simulations to investigate the growth and dynamical evolution of both single and multiple protoplanets in the disks with both inner viscously heated and outer stellar irradiated regions. The initial masses of the protoplanets are either assumed to be equal to$0.01 \ M_{\oplus}$or calculated based on the formula derived from streaming instability simulations. Our findings indicate that massive planets are more likely to form in disks with longer lifetimes, higher solid masses, moderate to high levels of disk turbulence, and larger initial masses of protoplanets. In the single protoplanet growth cases, the highest planet core mass that can be reached is generally lower than the threshold necessary to trigger rapid gas accretion, which impedes the formation of giant planets. Nonetheless, in multi-protoplanet cases, the cores can exceed the pebble isolation mass barrier aided by frequent planet-planet collisions. This consequently speeds up their gas accretion and promotes giant planet formation, making the optimal parameter space to grow giant planets substantially wider. Taken together, our results suggest that even around very low-mass stellar hosts, the giant planets with orbital periods of${\lesssim}100$days are still likely to form when lunar-mass protoplanets first emerge from planetesimal accretion and then grow rapidly by a combination of pebble accretion and planet-planet collisions in disks with a high supply of pebble reservoir${>}50 \ M_{\oplus}$and turbulent level of$\alpha_{\rm t} {\sim} 10^{-3}{-}10^{-2}$.Comment: 22 pages, 13 figures, 3 tables, Accepted for publication in A&

Effects of fiber orientation on tool wear evolution and wear mechanism when cutting carbon fiber reinforced plastics

The aim of the present paper is to reveal the influence of different fiber orientations on the tool wear evolution and wear mechanism. Side-milling experiments with large-diameter milling tools are conducted. A finite element (FE) cutting model of carbon fiber reinforced plastics (CFRP) is established to get insight into the cutting stress status at different wear stages. The results show that different fiber orientations bring about distinct differences in the extent, profile and mechanism of tool wear. Severer wear occurs when cutting 45° and 90° plies, followed by 0°, correspondingly, the least wear is obtained when θ = 135° (θ represents the orientation of fibers). Moreover, the worn profiles of cutting tools when θ = 0° and 45° are waterfall edge, while round edge occurs when θ = 135° and a combined shape of waterfall and round edge is obtained when θ = 90°. The wear mechanisms under different fiber orientations are strongly dependent on the cutting stress distributions. The evolution of tool wear profile is basically consistent with the stress distribution on the tool surface at different wear stages, and the extent of tool wear is determined by the magnitude of stress on the tool surface. Besides, the worn edges produce an actual negative clearance angle, which decreases the actual cutting thickness and leads to compressing and bending failure of fibers beneath the cutting region as well as low surface qualities

Analysis gait recognition performance based on the walking speed

This report proposes the gait recognition algorithm based on principal component analysis (PCA) for gait energy image (GEI) and analysts the impact of various walking speeds on the gait recognition. The gait energy image is obtained by preprocessing the original gait sequence. The eigenvalues ​​and the corresponding eigenvectors are extracted by the principal component analysis. After the principal components are obtained, they are projected to the low dimension space and classified using the k-nearest neighbor method. The algorithm is verified on the CASIA database. The experimental results show that the recognition performance can be effected by other factors except existing well-known factors.Bachelor of Engineerin

Analysis of 3-DOF Cutting Stability of Titanium Alloy Helical Milling Based on PKM and Machining Quality Optimization

Aiming at the requirements of titanium alloy holes in aircraft industry, the 3-DOF cutting stability and surface quality optimization of parallel kinematic manipulator (PKM) are studied. The variation of natural frequencies with the end-effector position of the PKM is analyzed. The cutting force model of titanium alloy helical milling based PKM is developed, and the cutting force coefficients are identified. The prediction model for 3-DOF the stability of helical milling based on the PKM is established through a Semi-Discrete method, and the stability lobes are obtained. The correctness of the stability lobes is verified by subjecting the cutting force signal to time-frequency transformation and roughness detection. The step-cutter is used for machining process improvement to enhance the stability domain. The method proposed in this paper can provide a reference for further optimization of the prediction and optimization of the milling process of difficult-to-process materials based on PKM in the future

Boosting the Performance of Lithium Metal Anodes with Three-Dimensional Lithium Hosts: Recent Progress and Future Perspectives

Li metal has emerged as a promising anode material for high energy density batteries, due to its low electrochemical potential and high specific capacity of 3860 mAh·g−1. These characteristics make it an attractive choice for electric vehicles and power grids. However, Li-metal batteries are plagued by dendrite issues stemming from the high reactivity of Li metal, which can ultimately result in battery failure or even safety concerns. To overcome this challenge, various strategies have been proposed to prevent dendrite formation and enhance the safety of Li-metal batteries. This review critically examines the recent progress in the development of dendrite-free Li-metal batteries, with a particular emphasis on advanced approaches of 3D Li metal host construction. Our goal is to provide a comprehensive overview of the 3D hosts for suppressing Li dendrites and to offer guidance for the future development of superior Li metal batteries

Pilot study of a novel classroom designed to prevent myopia by increasing children’s exposure to outdoor light

We sought to assess light characteristics and user acceptability of a prototype Bright Classroom (BC), designed to prevent children's myopia by exposing them to light conditions resembling the outdoors. Conditions were measured throughout the school year in the glass-constructed BC, a traditional classroom (TC) and outdoors. Teachers and children completed user questionnaires, and children rated reading comfort at different light intensities. A total of 230 children (mean age 10.2 years, 57.4% boys) and 13 teachers (36.8 years, 15.4% men) completed questionnaires. The median (Inter Quartile Range) light intensity in the BC (2,540 [1,330-4,060] lux) was greater than the TC (477 [245-738] lux, P < 0.001), though less than outdoors (19,500 [8,960-36,000] lux, P < 0.001). A prominent spectral peak at 490-560 nm was present in the BC and outdoors, but less so in the TC. Teachers and children gave higher overall ratings to the BC than TC, and light intensity in the BC in summer and on sunny days (>5,000 lux) was at the upper limit of children's comfort for reading. In summary, light intensity in the BC exceeds TC, and is at the practical upper limit for routine use. Children and teachers prefer the BC

Microenvironmental regulation in tumor progression: Interactions between cancer-associated fibroblasts and immune cells

The tumor microenvironment (TME), the ''soil'' on which tumor cells grow, has an important role in regulating the proliferation and metastasis of tumor cells as well as their response to treatment. Cancer-associated fibroblasts (CAFs), as the most abundant stromal cells of the TME, can not only directly alter the immunosuppressive effect of the TME through their own metabolism, but also influence the aggregation and function of immune cells by secreting a large number of cytokines and chemokines, reducing the body’s immune surveillance of tumor cells and making them more prone to immune escape. Our study provides a comprehensive review of fibroblast chemotaxis, malignant transformation, metabolic characteristics, and interactions with immune cells. In addition, the current small molecule drugs targeting CAFs have been summarized, including both natural small molecules and targeted drugs for current clinical therapeutic applications. A complete review of the role of fibroblasts in TME from an immune perspective is presented, which has important implications in improving the efficiency of immunotherapy by targeting fibroblasts

Forming giant planets around late-M dwarfs: Pebble accretion and planet-planet collision

We propose a pebble-driven core accretion scenario to explain the formation of giant planets around the late-M dwarfs of M★=0.1– 0.2 M⊙. In order to explore the optimal disk conditions for giant planet, we performed N-body simulations to investigate the growth and dynamical evolution of both single and multiple protoplanets in the disks with both inner viscously heated and outer stellar irradiated regions. The initial masses of the protoplanets are either assumed to be equal to 0.01 M⊕ or calculated based on the formula derived from streaming instability simulations. Our findings indicate that massive planets are more likely to form in disks with longer lifetimes, higher solid masses, moderate to high levels of disk turbulence, and larger initial masses of protoplanets. In the single protoplanet growth cases, the highest planet core mass that can be reached is generally lower than the threshold necessary to trigger rapid gas accretion, which impedes the formation of giant planets. Nonetheless, in multi-protoplanet cases, the cores can exceed the pebble isolation mass barrier aided by frequent planet–planet collisions. This consequently speeds their gas accretion up and promotes giant planet formation, making the optimal parameter space to grow giant planets substantially wider. Taken together, our results suggest that even around very-low-mass stellar hosts, the giant planets with orbital periods of ≲100 days are still likely to form when lunar-mass protoplanets first emerge from planetesimal accretion and then grow rapidly by a combination of pebble accretion and planet–planet collisions in disks with a high supply of a pebble reservoir >50 M⊕ and a turbulent level of αt ~ 10−3−10−2.B.L. and M.P. are supported by National Natural Science Foundation of China (Nos. 12222303, 12173035 and 12111530175), the start-up grant of the Bairen program from Zhejiang University and the Fundamental Research Funds for the Central Universities (2022-KYY-506107- 0001,226-2022-00216). A.J. acknowledges funding from the European Research Foundation (ERC Consolidator Grant 724687-PLANETESYS), the Knut and Alice Wallenberg Foundation (Wallenberg Scholar Grant 2019.0442), the Swedish Research Council (Project Grant 2018-04867), the Danish National Research Foundation (DNRF Chair Grant DNRF159) and the Göran Gustafsson Foundation. M.O. is funded by the National Natural Science Foundation of China (Nos. 12250610186, 12273023). W.S. is funded by the National Natural Science Foundation of China (Nos. 12033010, 12111530175), the B-type Strategic Priority Program of the Chinese Academy of Sciences (Grant No. XDB41000000), Foundation of Minor Planets of the Purple Mountain Observatory. J.J. appreciate support from the National Natural Science Foundation of China (Grant Nos. 12033010), the B-type Strategic Priority Program of the Chinese Academy of Sciences (Grant No. XDB41000000), Foundation of Minor Planets of the Purple Mountain Observatory. I.R. acknowledges financial support from the Agencia Estatal de Investigación of the Spanish Ministerio de Ciencia e Innovación MCIN/AEI/10.13039/501100011033 and the ERDF "A way of making Europe" through project PID2021-125627OB-C31, from the Centre of Excellence "María de Maeztu" award to the Institut de Ciències de l'Espai (CEX2020-001058-M) and from the Generalitat de Catalunya/CERCA programme. The computations are supported by cosmology simulation database (CSD) in the National Basic Science Data Center (NBSDC-DB-10).With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2020-001058-M).Peer reviewe

Essential Oil Extracted from Cymbopogon citronella Leaves by Supercritical Carbon Dioxide: Antioxidant and Antimicrobial Activities

To improve essential oil quality, especially to reserve the thermal instability of compounds, supercritical CO2 extraction (SFE) was applied to recover essential oil from Cymbopogon citronella leaves. A response surface methodology was applied to optimize the extraction process. The highest essential oil yield was predicted at extraction time 120  min, extraction pressure 25  MPa, extraction temperature 35°C, and CO2 flow 18  L/h for the SFE processing. Under these experimental conditions, the mean essential oil yield is 4.40%. In addition, the chemical compositions of SFE were compared with those obtained by hydrodistillation extraction (HD). There were 41 compounds obtained of SFE, while 35 compounds of HD. Alcohols and aldehydes were the main compositions in the essential oils. Furthermore, the antioxidant activities and antimicrobial of essential oils obtained by HD and the evaluated condition of SFE were compared. Results showed that the antioxidant activities of SFE oil are better than those of HD. Minimum inhibitory concentrations (MICs) were determined by the microdilution method. Essential oil obtained from SFE and HD exhibited a significant antimicrobial activity against all tested microorganisms. It is confirmed that the SFE method can be an alternative processing method to extract essential oils from Cymbopogon citronella leaves