Investigating the critical characteristics of thermal runaway process for LiFePO4/graphite batteries by a ceased segmented method

Lithium-ion batteries (LIBs) are widely used as the energy carrier in our daily life. However, the higher energy density of LIBs results in poor safety performance. Thermal runaway (TR) is the critical problem which hinders the further application of LIBs. Clarifying the mechanism of TR evolution is beneficial to safer cell design and safety management. In this paper, liquid nitrogen spray is proved to be an effective way to stop the violent reaction of LIBs during the TR process. Based on extended-volume accelerating rate calorimetry, the liquid nitrogen ceasing combined with non-atmospheric exposure analysis is used to investigate the TR evolution about LiFePO4/graphite batteries at critical temperature. Specifically, the geometrical shape, voltage, and impedance change are monitored during the TR process on the cell level. The morphologies/constitution of electrodes and separators are presented on the component level. Utilizing the gas analysis, the failure mechanism of the prismatic LiFePO4/graphite battery is studied comprehensively

Inversion boundary annihilation in GaAs Monolithically grown on on-axis Silicon (001)

Monolithic integration of III–V materials and devices on CMOS compatible on‐axis Si (001) substrates enables a route of low‐cost and high‐density Si‐based photonic integrated circuits. Inversion boundaries (IBs) are defects that arise from the interface between III–V materials and Si, which makes it almost impossible to produce high‐quality III–V devices on Si. In this paper, a novel technique to achieve IB‐free GaAs monolithically grown on on‐axis Si (001) substrates by realizing the alternating straight and meandering single atomic steps on Si surface has been demonstrated without the use of double Si atomic steps, which was previously believed to be the key for IB‐free III–V growth on Si. The periodic straight and meandering single atomic steps on Si surface are results of high‐temperature annealing of Si buffer layer. Furthermore, an electronically pumped quantum‐dot laser has been demonstrated on this IB‐free GaAs/Si platform with a maximum operating temperature of 120 °C. These results can be a major step towards monolithic integration of III–V materials and devices with the mature CMOS technology

Integrating Spatial Heterogeneity into an Analysis between Ecosystem Service Value and Its Driving Factors: A Case Study of Dalian, China

Human demand for natural resources has grown, leading to ecological debasement and related ecological system administration. Using Dalian as an example, we estimated the changes in the ecosystem service value (ESV) in 2005 and 2020. We used ArcGIS and spatial statistics to conduct estimations and change analyses of the ESV. Based on the results of the ESV, the geographical detector and geographically weighted regression (GWR) elucidated the contributions of different driving factors of the ESV in a 2 km grid. In summary, these results indicated that: (1) from a holistic perspective, the ESV of Dalian fell by 206.8009 billion CNY over 15 years, and the hot spots were concentrated in both the northern and the western parts, whereas the cold spots were distributed in the central part; (2) according to the results from the geographical detector, land use structure factors influenced the ESV most significantly, followed by socio-economic factors, and the impact of natural factors was relatively small; and (3) according to the results of the GWR, land use structure factors negatively affected the ESV, and the positive impact of the proportion of the natural land area was the most obvious. We conclude that the decline in the ESV reflects the impact of human activities on the ecosystem in the studied landscape. Understanding ESV changes should be made a priority in ecosystem management, and evaluating ESV drivers can contribute to developing land use strategies for policy-making

Quantum Dot-based Immunohistochemistry for Pathological Applications

Quantum dots (QDs) are novel light emitting semiconductor nanocrystals with diameter ranging from 2 to 20 nm. In comparison with traditional organic dyes and fluorescent proteins, QDs possess unique optical properties including extremely high fluorescence efficiency and minimal photobleaching which make them emerge as a new class of fluorescent labels for molecular imaging and biomedical analysis. Herein, recent advances in fundamental mechanisms and pathological applications of QD were reviewed

Video-Based Two-Stage Network for Optical Glass Sub-Millimeter Defect Detection

Since tiny optical glass is the key component in various optical instruments, more and more researchers have paid attention to automatic defect detection on tiny optical glass in recent years. It remains a challenging problem, as the defects are extremely small. In this paper, we propose a video-based two-stage defect detection network to improve detection accuracy for small defects. Specifically, the detection process is carried out in a coarse-to-fine manner to improve the detection precision. First, the optical glass area is located on the down-sampled version of the input image, and then defects are detected only within the optical glass area with a higher resolution version, which can significantly reduce the false alarming rate. Since the defects may exist on any place of the optical glass, we fuse the results of multiple video frames captured from various perspectives to promote recall rates of the defects. Additionally, we propose an image quality evaluation module based on a clustering algorithm to select video frames with high quality for improving both detection recall and precision. We contribute a new dataset called OGD-DET for tiny-scale optical glass surface defect detection experiments. The datasets consist of 3415 images from 40 videos, and the size of the defect area ranges from 0.1 mm to 0.53 mm, 2 to 7 pixels on images with a resolution of 1536 × 1024 pixels. Extensive experiments show that the proposed method outperforms the state-of-the-art methods in terms of both accuracy and computation cost

Video-Based Two-Stage Network for Optical Glass Sub-Millimeter Defect Detection

Since tiny optical glass is the key component in various optical instruments, more and more researchers have paid attention to automatic defect detection on tiny optical glass in recent years. It remains a challenging problem, as the defects are extremely small. In this paper, we propose a video-based two-stage defect detection network to improve detection accuracy for small defects. Specifically, the detection process is carried out in a coarse-to-fine manner to improve the detection precision. First, the optical glass area is located on the down-sampled version of the input image, and then defects are detected only within the optical glass area with a higher resolution version, which can significantly reduce the false alarming rate. Since the defects may exist on any place of the optical glass, we fuse the results of multiple video frames captured from various perspectives to promote recall rates of the defects. Additionally, we propose an image quality evaluation module based on a clustering algorithm to select video frames with high quality for improving both detection recall and precision. We contribute a new dataset called OGD-DET for tiny-scale optical glass surface defect detection experiments. The datasets consist of 3415 images from 40 videos, and the size of the defect area ranges from 0.1 mm to 0.53 mm, 2 to 7 pixels on images with a resolution of 1536 × 1024 pixels. Extensive experiments show that the proposed method outperforms the state-of-the-art methods in terms of both accuracy and computation cost

Guiding sustainable urban development via a multi-level ecological framework integrating natural and social indicators

Establishing a sustainable landscape pattern to cope with worsening ecological problems is an internationally recognized practice. However, previous studies have not considered the joint supply equilibrium of ecosystem services (ESs) and coupling with social systems. In this study, we propose an ecological security pattern framework composed of multi-level ecological elements, based on ESs, human impacts, and improved connectivity. The ordered weighted averaging decision model was used to analyze the four types of ESs specified by the Millennium Ecosystem Assessment and extract core patches. Based on potential corridors extracted by the minimum cumulative resistance model, ecological corridors were further classified by improved connectivity analysis coupled with the human modification index. The approach was tested using data from Dalian, Liaoning Province, China. The results show that the most service capabilities declined to varying degrees over the past 10 years. Forests, arable land, and grasslands had relatively high levels of comprehensive ecological services. Regulating services showed a significant decline in three or more land types. The principle of landscape ecology promotes the establishment of a buffer zone. In Dalian, the areas of the ecological core patch and buffer zone were 2,167.88 and 5,377.38 km2, respectively. The three levels of potential ecological corridors totaled 1079.78 km. The ecological elements and ESs assessment results obtained using the proposed method provide spatial guidance for ecological management, thereby ensuring the sustainable development of large cities

Effect of biodegradable Zn screw on bone tunnel enlargement after anterior cruciate ligament reconstruction in rabbits

Zn and its alloys have recently emerged as new options for orthopedic implants due to their desirable biodegradation rate and mechanical strength. However, whether Zn metallic implants attenuate bone tunnel enlargement (BTE) after anterior cruciate ligament (ACL) reconstruction and, if so, the underlying mechanism by which this occurs remains elusive. In present study, we explored the possibility of using pure Zn screws to attenuate BTE in rabbits, and the potential molecular mechanism was further explored in primary osteoblasts. Here, our study showed that the pure Zn screws more effectively attenuated BTE after ACL reconstruction in rabbits compared with pure Mg and Ti screws. This was attributed to the fact that the pure Zn screw-released Zn element diminished the size of the femoral tunnels, enhanced the bone mass around the screws, boosted the fixation strength, and promoted the tendon-bone integration. Several lines of cellular evidences suggested that Zn metallic implant-released Zn element induced upregulation of sodium-dependent vitamin C transporter 2 in primary osteoblasts and ultimately elevated the expressions of the osteogenic transcription factors to trigger osteogenic differentiation. This study showed that biodegradable Zn metallic materials were promising candidates for interference screw to attenuate BTE after ACL reconstruction