纽约大都市区区域绿色空间规划演进（1922—2020年）及启示

纽约区域规划协会（Regional Plan Association, RPA）是世界上最早开始实施区域规划的专业组织之一,自20世纪20年代以来,纽约大都市地区共开展了4次区域规划并进行了大量专项研究,规划持续了近百年,产生了世界一流的研究成果。通过聚焦4次区域规划中的绿色空间规划,对其规划背景、核心理念、规划内容进行研究,分析总结纽约大都市区区域绿色空间规划的演进特点和规律,得出以社会问题为导向、以专项研究为支撑的同质性特征,以及在自然观、研究视野和规划目标方面的异质性特征。在此基础上,从空间范畴、规划内容、规划方法、组织方式等方面,提出了对中国城市区域绿色空间规划的启示。     

Replication Protein A Enhances Kinetics of Uracil DNA Glycosylase on ssDNA and Across DNA Junctions: Explored with a DNA Repair Complex Produced with SpyCatcher/SpyTag Ligation

DNA repair proteins participate in extensive protein−protein interactions that promote the formation of DNA repair complexes. To understand how complex formation affects protein function during base excision repair, we used SpyCatcher/SpyTag ligation to produce a covalent complex between human uracil DNA glycosylase (UNG2) and replication protein A (RPA). Our covalent “RPA−Spy−UNG2” complex could identify and excise uracil bases in duplex areas next to ssDNA−dsDNA junctions slightly faster than the wild-type proteins, but this was highly dependent on DNA structure, as the turnover of the RPA−Spy−UNG2 complex slowed at DNA junctions where RPA tightly engaged long ssDNA sections. Conversely, the enzymes preferred uracil sites in ssDNA where RPA strongly enhanced uracil excision by UNG2 regardless of ssDNA length. Finally, RPA was found to promote UNG2 excision of two uracil sites positioned across a ssDNA−dsDNA junction, and dissociation of UNG2 from RPA enhanced this process. Our approach of ligating together RPA and UNG2 to reveal how complex formation affects enzyme function could be applied to examine other assemblies of DNA repair proteins.     

RPA分析天然橡胶不同硫化体系的动态性能

用RPA分析不同硫化体系对NR动态性能的影响进行研究。研究发现：频率增加,混炼胶和硫化胶的G’增加,混炼胶的Tanδ减小,硫化胶的Tanδ增加;应变增加,混炼胶和硫化胶的G’减小,混炼胶的Tanδ在应变大于20%迅速增加,硫化胶的Tanδ在应变2%出现峰值;温度增加,混炼胶的G’减小、Tanδ增加,硫化胶的G’增加、Tanδ减小。不同硫化体系三种扫描下,硫化胶的G’顺序：SEV>EC>CV>EV,主要是单硫键、双硫键与多硫键保持一定的比例才能获得较高的G’。     

滑石粉/炭黑并用对丁腈橡胶性能的影响

研究滑石粉/炭黑并用量对丁腈橡胶(NBR)胶料性能的影响。结果表明,随着滑石粉用量的增大,NBR胶料的加工性能改善,交联程度下降,硫化胶的100%定伸应力、回弹值和压缩永久变形增大,拉伸强度和撕裂强度减小,耐热性能和耐非极性油性能提高,压缩模量增幅增大,弹性模量降低,Payne效应减弱,损耗因子减小。     

A Novel Isothermal Assay of Borrelia burgdorferi by Recombinase Polymerase Amplification with Lateral Flow Detection

A novel isothermal detection for recombinase polymerase amplification with lateral flow (LF-RPA) was established for Borrelia burgdorferi (B. burgdorferi) detection in this study. This assay with high sensitivity and specificity can get a visible result without any additional equipment in 30 min. We designed a pair of primers according to recA gene of B. burgdorferi strains and a methodology evaluation was performed. The results showed that the RPA assay based on the recA gene was successfully applied in B. burgdorferi detection, and its specific amplification was only achieved from the genomic DNA of B. burgdorferi. The detection limit of the new assay was about 25 copies of the B. burgdorferi genomic DNA. Twenty Lyme borreliosis patients’ serum samples were detected by LF-RPA assay, real-time qPCR and nested-PCR. Results showed the LF-RPA assay is more effective than nested-PCR for its shorter reaction time and considerably higher detection rate. This method is of great value in clinical rapid detection for Lyme borreliosis. Using the RPA assay might be a megatrend for DNA detection in clinics and endemic regions.     

适用于RPA工具的卷积序列推荐算法

在机器人流程自动化(Robotic Process Automation, RPA)软件中,经常采用序列推荐系统让机器人完成判断、选择等人工处理的任务。然而常用的序列推荐系统受限于序列信息的提取困难等问题,难以得到广泛应用。为了解决这一问题,构建一种基于Inception的卷积序列推荐模型,把时间和潜在空间中的用户行为序列信息嵌入进一幅“图像”中,并通过动态和静态2种不同的卷积层提取其中的局部特征,全面地提取用户的短期兴趣偏好,同时将用户嵌入矩阵作为用户的长期兴趣偏好嵌入到卷积层的输出中,共同构建完整的用户兴趣偏好,提升推荐性能。通过在3种公开数据集MovieLens 1M、Gowalla、Steam上分别进行实验,验证了基于Inception的卷积序列推荐模型的性能优于最新的序列推荐模型,在Top-N序列推荐的3种评价指标中（精确率、召回率、平均AP值）,平均提升幅度在10%左右,单个指标上的最大提升幅度为14%。     

一种新的基于隐喻地图的RPA路径规划算法

智能化地制定机器人流程自动化(robotic process automation, RPA)执行路径有利于企业节约相关人力成本以及提高RPA的推广,提出基于改进深度双Q网络(double deep Q-learning algorithms, DDQN)算法进行RPA路径规划。首先针对存在RPA的作业环境即Web页面,不满足深度增强算法的探索条件的问题,借助隐喻地图的思想,通过构建虚拟环境来满足路径规划实验要求。同时为了提高DDQN算法探索效率,提出利用样本之间的位置信息的杰卡德系数,将其作为样本优先度结合基于排名的优先级(rank-based prioritization)构建新的采样方式。通过随机采用任务样本在虚拟环境上进行验证,证明其符合实验要求。进一步比较改进DDQN、深度Q网络(deep Q network, DQN)、DDQN、PPO以及SAC-Discrete算法的实验结果,结果显示改进算法的迭代次数更少、收敛速度更快以及回报值更高,验证了改进DDQN的有效性和可行性。     

Characterization of an ionic liquid electrospray thruster with a porous ceramic emitter

An ionic liquid(IL) electrospray thruster was developed for application in micro-nano satellites or gravitational wave detectors. The thruster employed a porous ceramic emitter with seven emitter strips located on its emission surface. Without any liquid-supply device, IL was delivered through porous media to emitter strips via capillary effect. Multiple emission sites then formed at the tip of each strip. A charged beam of up to 350 μA(with a current density of 540 μA cm~(-2))was stably produced in the negative mode. However, in the positive mode, a corona was observed which could prevent the thruster from emitting larger current. A time-of-flight mass spectrometer with significantly improved signal-to-noise ratio was built, which was used to obtain the mass distribution of the beam of the thruster. A retarding potential analysis was also performed. The test results showed that the thruster worked in the pure-ion regime, and delivered a maximum thrust of 67.1 μN with specific impulses of 3952 s and 3117 s in the positive and negative modes, respectively.