基于深度学习的心脏图像分割研究现状

面对严重的医学影像分析缺口,深度学习的发展能够满足国内医疗行业的需求。心脏图像的处理方法可大致分为传统的图像处理技术、基于图谱的方法（atlas-based methods）、基于模型的方法（model-based methods）以及目前热门的采用机器学习和深度学习的方法。在深度学习兴起之前,传统的机器学习技术如模型法和图集法在心脏图像分割中有良好表现,但通常需要大量的特征工程知识或先验知识才能获得令人满意的精度。而基于深度学习的算法能从数据中自动发现复杂的特征以进行对象检测和分割。得益于先进的计算机硬件以及更多可用于训练的数据集,基于深度学习的分割算法已超越了以往的传统方法。本文回顾了2012—2022年有关心室、心外膜和心包脂肪的图像处理的各项方法、衡量指标及其目前的研究现状,并结合分割技术的发展,讨论了心脏分割的发展趋势。     

A blockchain-based trustworthy collaborative power trading scheme for 5G-enabled social internet of vehicles

Social Internet of Vehicles (SIoV) falls under the umbrella of social Internet of Things (IoT), where vehicles are socially connected to other vehicles and roadside units that can reliably share information and services with other social entities by leveraging the capabilities of 5G technology, which brings new opportunities and challenges, e.g., collaborative power trading can address the mileage anxiety of electric vehicles. However, it relies on a trusted central party for scheduling, which introduces performance bottlenecks and cannot be set up in a distributed network, in addition, the lack of transparency in state-of-the-art Vehicle-to-Vehicle (V2V) power trading schemes can introduce further trust issues. In this paper, we propose a blockchain-based trustworthy collaborative power trading scheme for 5G-enabled social vehicular networks that uses a distributed market mechanism to introduce trusted power trading and avoids the dependence on a centralized dispatch center. Based on the game theory, we design the pricing and trading matching mechanism for V2V power trading to obtain maximum social welfare. We use blockchain to record power trading data for trusted pricing and use smart contracts for transaction matching. The simulation results verify the effectiveness of the proposed scheme in improving social welfare and reducing the load on the grid.     

Cu-8%Ag合金的超重力凝固:微观组织

在常重力场和N g超重力场下制备了Cu-8%Ag(质量分数)合金试样,研究了超重力对Cu-8%Ag合金凝固组织的影响。结果表明,超重力引起的熔体对流对试样底部的冲刷作用强于试样顶部,造成底部柱状枝晶的生长弱于试样顶部,超重力试样得到了细小均匀的等轴晶区,Ag棒状析出相的直径由常重力的56.1 nm细化到超重力下的39.2 nm,超重力没有产生明显的宏观偏析,但会影响Ag在Cu基体和离异共晶组织中的分布。     

近红外二区共聚焦显微技术的进展及应用（特邀）

共聚焦显微镜具有较高的空间分辨率和信号背景比,能对生物样品进行三维层析成像,在医学与生物学领域有着广泛的应用。近红外二区（NIR-II,900~1 880 nm）波段的光在生物组织中具有适中的吸收、较低的散射,以及非常弱的生物组织自发荧光,因此,NIR-II荧光活体成像具有大深度、高对比度等优势。点激发、点探测的NIR-II共聚焦显微技术结合了上述二者的优势,在大深度生物成像中具有高空间分辨率和高信号背景比等优点,因此在生物医学领域得到了广泛应用。此综述将从NIR-II共聚焦显微技术的原理出发,阐述其发展进程、以及基于此项技术开展的生物医学成像应用,探讨NIR-II共聚焦显微技术未来的改进和发展方向。     

Estimating the impact of cloud computing on firm performance: An empirical investigation of listed firms

This study empirically investigates the economic impact of cloud service adoption on firm performance. We exploit the difference-in-differences models coupled with propensity score-based matching to estimate the performance effect of cloud computing on worldwide listed firms that adopted cloud service during 2010–2016. The results indicate that cloud computing has a significant and positive impact on the profitability and market value of listed firms with varying degrees in both short and long time periods. In addition, the magnitude of the performance effect varies with firm size and industry type. This research contributes to empirical examination on the economic values of IT investments.     

Aggregation-induced emission luminogen-assisted stimulated emission depletion nanoscopy for super-resolution mitochondrial visualization in live cells

Nano Research - Aggregation-induced emission luminogens (AIEgens) are fluorescent agents that are ideal for bioimaging and have been widely used for organelle targeting, cellular mapping, and...     

基于生物炭增强的竹纤维/玉米醇溶蛋白复合膜的拉伸性能

为改善玉米醇溶蛋白(Zein)的拉伸性能,本文以竹粉为原料制备生物炭,以球磨后的生物炭(0.536 μm)、竹纤维(2.157 μm)为增强相,以Zein为连续相,利用溶液浇注法制备复合膜材料,并对复合膜材料的基本特性与拉伸性能进行了研究。结果表明,生物炭与竹纤维加入没有改变Zein的晶面结构,提高了Zein的无序性,降低了Zein的脆性,提高了Zein的韧性。生物炭的加入降低了竹纤维/Zein复合膜的亲水性,降低了竹纤维/Zein复合膜的热稳定性,改善了竹纤维/Zein复合膜的拉伸性能。相比而言,添加0.2 g竹纤维、0.1 g生物炭的Zein复合膜材料的拉伸性能最佳,其拉伸强度、拉伸模量、断裂伸长率分别为0.24 MPa、4.17 MPa、327.27%。本文制备的复合膜材料具有较好的拉伸性能,在包装膜材料领域具有一定的应用潜力。      

Fabrication of fluidic chips with 1-D nanochannels on PMMA substrates by photoresist-free UV-lithography and UV-assisted low-temperature bonding

A novel method for fabricating nano- or submicro-fluidic PMMA chips using photoresist-free UV-lithography and UV-assisted low-temperature bonding was developed. The nano- or submicro-channels were fabricated by exposing the PMMA substrate to the UV-light through a mask for a certain time. The PMMA substrate with channels and another flat PMMA cover sheet were pretreated with the UV-light for 2 h before they were brought together in running water. The bonding was carried out under a pressure of (1.19 ± 0.12) × 10⁵ Pa and at a temperature of 45°C for 35 min. The chips bonded in this way could bear a tensile of 6.71 ± 2.50 MPa, and the deformation of the bonded channel was about 13%. A hybrid micro- and nano-fluidic PMMA chip fabricated with the developed method was demonstrated for the test of the electrokinetically driven ion enrichment and ion depletion.     

Design reuse oriented partial retrieval of CAD models

As a huge number of 3D CAD models is generated each year, retrieval of 3D CAD models is becoming more and more important for achieving design reuse. However, the existing methods for partial retrieval of 3D CAD models are very few and far from the requirements of design reuse. In this paper, we present an approach to partial retrieval of 3D CAD models for design reuse. The criteria for determining whether a subpart of 3D CAD models is reusable for design is defined first. Based on the criteria defined, all the design reusable subparts involved in the 3D CAD models in the library are automatically extracted and stored in the library as reference models. Moreover, each design reusable subpart in the library is represented by all its local matching regions in a hierarchical way so as to support multi-mode partial retrieval. In our approach, three partial retrieval modes including normal retrieval, exact retrieval and relaxed retrieval are defined to meet various partial retrieval requirements of design reuse such as the incomplete and vague queries during the early design stage. And the multi-mode partial retrieval is achieved by performing multi-mode matching and similarity assessment between the query and the design reusable subparts in the library indexed by bitmap. Experimental results are presented to demonstrate the effectiveness of the approach.     

An equivalent method for blasting vibration simulation

Due to the complicated blasting load, the diversified medium models and various constitutive relations of the rock mass, and a huge job for simulating blasting of multiple holes, it is very difficult and costly to simulate the blasting vibration accurately in numerical computation. This paper presents an equivalent simulation method so as to transform this complex dynamic problem into an approximate initial-boundary problem. The equivalent elastic boundary applied by the blasting load was developed for multiple holes according to the spatial distribution of rock damage around each blasthole. The equivalent mechanics process of the complex blasting load was performed through analysis of the expansion of the borehole volume, the growth of cracks, the movement of stemming and the outburst of detonation gases. In combination with the blasting excavation of the tailrace tunnel in the Pubugou Hydropower Station, particle vibration velocities in the surrounding rock at different distances from the explosion source were simulated by applying this equivalent method based on the dynamic finite element method. The comparison with field monitoring data indicates that this equivalent simulation method is applicable to predicting the far-field dynamic response of the ground subjected to blasting load, and the selection of rock mass properties near the equivalent elastic boundary has a significant impact on simulation results.