高性能有机氟材料制备科学及应用进展

有机氟材料具有优异的热氧稳定性、耐化学腐蚀性、耐老化性、不黏性、电绝缘性以及极小的摩擦系数等特性，因此作为一种不可替代的材料广泛应用于高新技术产业。近年来高新技术产业发展对高性能有机氟材料的需求引发了学术界和工业界对氟材料的研究兴趣。依据本文作者的研究经历及有机氟材料的发展方向，本文介绍了氟树脂（新型含氟聚合物、电活性含氟聚合物、新型全氟磺酸聚合物、聚四氟乙烯3D打印）及氟橡胶（过氧化物硫化氟橡胶、耐低温氟醚橡胶、耐高温全氟醚橡胶、全氟聚醚基类玻璃橡胶）的制备科学及应用进展，特别阐述为了满足航空航天、能源、信息等高新技术产业需求发展的新一代高性能有机氟材料。本文也介绍了近期出现的聚四氟乙烯新成型技术及类玻璃氟橡胶。文章指出发展绿色环保和高效的高性能有机氟材料制备及成型加工方法是今后的发展方向。     

Automatic breast tumor detection in ABVS images based on convolutional neural network and superpixel patterns

Breast cancer is one of the most common female malignancies, as well as the second leading cause of mortality for women. Early detection and treatment can dramatically decrease the mortality rate. Recently, automated breast volume scanner (ABVS) has become one of the most frequently used diagnose methods for breast tumor screening because of its operator-independent and reproducible advantages. However, it is a challenging job to obtain the tumors’ accurate locations and shapes by reviewing hundreds of ABVS slices. In this paper, a novel computer-aided detection (CADe) system is developed to reduce clinicians’ reading time and improve the efficiency. The CADe system mainly contains three parts: tumor candidate acquisition, false-positive reduction and tumor segmentation. Firstly, a local phase-based approach is built to obtain breast tumor candidates for further recognition. Subsequently, a convolutional neural network (CNN) is applied to reduce false positives (FPs). The introduction of CNN can help to avoid complicated feature extraction as well as elevate the accuracy and efficiency. Finally, superpixel-based segmentation is used to outline the breast tumor. Here, superpixel-based local binary pattern (SLBP) is proposed to assist the segmentation, which improves the performance. The methods were evaluated on a clinical ABVS dataset whose abnormal cases were manually labeled by an experienced radiologist. The experiment results were mainly composed of two parts. At the FP reduction stage, the proposed CNN achieved 100% and 78.12% sensitivity with FPs/case of 2.16 and 0. At the segmentation stage, our SLBP obtained 82.34% true positive, 15.79% false positive and 83.59% Dice similarity. In summary, the proposed CADe system demonstrated promising potential to detect and outline breast tumors in ABVS images.

     

High performance hardware architecture for singular spectrum analysis of Hankel tensors

This paper presents a hardware architecture for singular spectrum analysis of Hankel tensors, including computation of tucker decomposition, tensor reconstruction and final Hankelization. In the proposed design, we explore two level of optimization. First, in algorithm level, we optimize the calculation process by exploiting the Hankel property to reduce the computation complexity and on-chip BRAM resource usage. Secondly, in hardware level, parallelism is explored for acceleration. Resource sharing is applied to reduce look-up tables (LUTs) usage. To enable flexibility, the number of processing elements (PEs) can be changed through parameter setting. Our proposed design is implemented on Field-Programmable Gate Arrays (FPGAs) to process third order tensors. Experiment results show that our design achieve a speed-up from 172 to 1004 compared with CPU implementation via Intel MKL and 5 to 40 compared with GPU implementation.     

软土地区管幕群顶管施工地面沉降监测与分析

依托上海14号线桂桥路站管幕段实例工程,对管幕群顶管顶进施工过程地面沉降情况进行监测,分析群顶管施工对地面沉降的影响,在此过程中对本工程采用水土分算或合算进行讨论。根据顶进过程实际工况和监测数据,分析管幕群顶管施工影响地面的原因,提出相应控制措施。结果表明:①管幕群顶管施工引起最大地面沉降出现在始发井出加固区区域;②在本工程中采用水土合算计算正面土压力较为符合实际情况;③管幕群顶管施工过程中影响地面变形的因素主要包括前舱压力、顶进速度、洞门止水、管壁摩擦和同步注浆等方面。     

抗新型冠状病毒2019-nCoV新药的研发

2019年底，湖北武汉暴发了2019新型冠状病毒感染疾病（COVID-19），并快速在全国蔓延，且在多个国家发现病例。其感染病例和死亡病例在短时间内快速超过重症急性呼吸综合征（SARS），给中国带来了不可估量的损失。中国科研人员在短时间内，快速锁定病原体为2019-nCoV（或hCoV-19或SARS-CoV-2)，并且在不同层面开展了相关抗病毒药物的研发工作。本文介绍了抗2019-nCoV新药研发的现状。同时，鉴于突发病原体的药物研发过程相对迟缓，我们建议对于潜在流行可能性的病原体，其药物研发要具有前瞻性，国家层面要推进广谱药物的研发和临床试验，以应对可能出现的疫情风险。     

An investigation on the recycling of hydrated cement from concrete demolition waste

Construction and demolition waste (CDW) recycling is generally limited to the use of the coarser fraction as aggregate for new concrete. The recovery of fine aggregates requires a cleaning by removing the hydrated cement waste (HCW). In this paper, the possibility to use HCW extracted from CDW as alternative component for the production of new clinker is explored.A pure HCW sample was prepared and used in partial replacement of natural materials in raw admixtures for new clinker production. At a replacement degree of 30%, a new Portland clinker containing almost 50% of C₃S could be produced with a huge spare in the release of CO₂ (about 1/3 less). At higher HCW dosage a non-Portland clinker containing almost 80% of C₂S has been obtained: its use as supplementary cementing material in blended cements revealed satisfying long term performances.     

Naturally Occurring Polyphenolic Glucosidase Inhibitors

Polyphenols, which are abundantly distributed in plants such as fruits, vegetables, and tea, constitute a large group of aromatic compounds, mainly including phenolic acids and flavonoids. These natural metabolites have been demonstrated to possess a wide range of biological activities associated with health benefits, including the α-glucosidase inhibitory activity. In contrast to the classical α-glucosidase inhibitors, e.g., aza/imino sugars, polyphenols serve as a new type of α-glucosidase inhibitor with different, yet unknown, mechanisms of action, which could lead to novel dietary supplements and therapeutic agents for the prevention and treatment of metabolic disorders. In this review, we report a collection of 137 naturally occurring phenolic acids and flavonoids with α-glucosidase inhibitory activities.     

Performances at high temperature of RC bridge decks strengthened with EBR-FRP

Fiber reinforced polymer (FRP) can be successfully used to externally strengthen reinforced concrete (RC) bridges where fire is not a primary concern. Nevertheless, common maintenance activity on a bridge deck, such as the laying of bituminous paving, can easily lead the FRP to temperatures higher than the glass transition temperature, T_g. Exceeding T_g does not necessarily imply a drastic reduction in strength and stiffness of the reinforcement. Nevertheless, the softening of the resin implies a drastic reduction in its adhesion properties. Therefore, the efficiency of the strengthening system for existing structures, which mainly depends on the effectiveness of the bond between FRP and concrete, is significantly affected by temperature.The relationships suggested by Italian and American codes in order to evaluate the limit strain for FRP debonding at normal temperature are modified to take into account the effect of high temperature. Then, performances at high temperature of RC bridge decks strengthened with externally bonded FRP plates (EBR) are investigated by considering thermal fields in the structural members which are different from the normal ones. Both fire and the laying of bituminous paving on the decks are considered. In addition, the thicknesses of the slabs and the protective layer are varied to assess their influence on the thermal field in the slabs. The results are discussed with reference to both ultimate and serviceability limit states.