Dipping Process Characteristics Based on Image Processing of Pictures Captured by High-speed Cameras

The dipping process was recorded firstly by high-speed camera system; acceleration time, speed, and dipping time were set by the control system of dipping bed, respectively. By image processing of dipping process based on Otsu's method, it was found that low-viscosity flux glue eliminates the micelle effectively, very low speed also leads to small micelle hidden between the bumps, and this small micelle and hidden phenomenon disappeared when the speed is ≥0.2 cm s-1. Dipping flux quantity of the bump decreases by about 100 square pixels when flux viscosity is reduced from4,500 to 3,500 mpa s. For the 3,500 mpa s viscosity glue, dipping flux quantity increases with the increase of the speed and decreases with the increase of the speed after the speed is up to 0.8 cm s-1. The stable time of dipping glue can be obtained by real-time curve of dipping flux quantity and is only 80–90 ms when dipping speed is from 1.6 to 4.0 cm s-1. Dipping flux quantity has an increasing trend for acceleration time and has a decreasing trend for acceleration. Dipping flux quantity increases with the increase of dipping time, and is becoming saturated when the time is ≥55 ms.

高温形状记忆聚酰亚胺的合成

作为一种典型的智能材料,形状记忆聚酰亚胺(Shape Memory Polyimide,SMPI)因其优异的高温形状记忆效应和做功能力,在航空航天和智能光电等尖端领域展示了广阔的应用前景。本实验通过设计一种简单、有效的装置实现无水无氧条件,以1,3-双(3-氨基苯氧基)苯与4,4’-氧代双邻苯二甲酸酐为原料合成聚酰胺酸前驱体,采用梯度升温法制得SMPI。通过凝胶色谱、红外光谱、动态热机械分析和热重分析等方法对产物进行表征。所得SMPI呈现优异的形状记忆效应,高温下可推翻超过自身重量11.93倍的金属板,具有良好的做功能力。本实验涵盖了高分子化学合成、产物结构表征、力学性能测试及应用,具有较强的综合性;此外,实验现象稳定、重现性好,适合本科实验教学。通过模拟“天问一号”红旗的展开,激发学生科研兴趣,培养创新思维,提高综合素质;同时让学生领略到中国航天的独特风采,增强民族自豪感。

2020年春节前后京津冀“低排放”重污染事件

以2020年春节和新型冠状病毒肺炎(COVID-19)疫情管控期间京津冀地区连续发生的两次持续性重污染天气过程为对象,探讨持续减排和较低社会活动水平背景下,持续性重污染天气形成和维持的原因,并在综合诊断分析的基础上,通过标准化多元线性回归的方法量化了各关键气象因子对京津冀持续性重污染天气的相对贡献。研究表明,低层东部沿海高压稳定维持使近地面持续异常高湿和高层异常阻塞高压系统停滞是诱发京津冀污染天气持续的两个关键气象影响因子;持续且稳定的偏东和偏南异常水汽输送结构为京津冀区域源源不断地提供了比以往更多的水汽,有利于气溶胶吸湿增长;尤其在高层异常阻塞高压系统停滞的背景下,受其下沉增温效应影响更易于对流层中部“暖盖”结构的形成,构成有利于污染物累积的高湿静稳天气条件,从而驱动污染天气发展与维持;京津冀2020年春节前后两次持续性重污染天气过程中阻塞高压系统与异常水汽输送这两个关键气象因子协同作用相对贡献率可达46.8%.

Phosphor-free single chip GaN-based white light emitting diodes with a moderate color rendering index and significantly enhanced communications bandwidth

To achieve high quality lighting and visible light communication(VLC)simultaneously,Ga N based white light emitting diodes(WLEDs)oriented for lighting in VLC has attracted great interest.However,the overall bandwidth of conventional phosphor converted WLEDs is limited by the long lifetime of phosphor,the slow Stokes transfer process,the resistance-capacitance(RC)time delay,and the quantum-confined Stark effect(QCSE).Here by adopting a self-assembled In Ga N quantum dots(QDs)structure,we have fabricated phosphor-free single chip WLEDs with tunable correlated color temperature(CCT,from 1600 K to 6000 K),a broadband spectrum,a moderate color rendering index(CRI)of 75,and a significantly improved modulation bandwidth(maximum of150 MHz)at a low current density of 72 A∕cm^2.The broadband spectrum and high modulation bandwidth are ascribed to the capture of carriers by different localized states of In Ga N QDs with alleviative QCSE as compared to the traditional In Ga N/Ga N quantum well(QW)structures.We believe the approach reported in this work will find its potential application in Ga N WLEDs and advance the development of semiconductor lighting-communication integration.

Reservoir accumulation conditions and key exploration&development technologies for Keshen gas field in Tarim Basin

The Keshen gas field is located in the central part of Kuqa foreland thrust belt in Tarim Basin,and is another large gas field discovered in Kuqa depression after Kela 2 gas field.Since the breakthrough in 2008,a number of large and medium scale gas reservoirs including Keshen 2,Keshen 5 and Keshen 8 have been discovered,that are characterized by ultra depth,ultra-high pressure,ultra-low porosity,ultra-low permeability,high temperature and high pressure.With natural gas geological reserves of nearly trillion cubic meters and production capacity of nearly 5.5 billion cubic meters,the Keshen gas field is the main natural gas producing area in Tarim Oilfield.The Keshen gas field is located in a series of thrusting imbrication structures in the Kelasu structural belt of Kuqa foreland thrust belt.The salt roof structure,plastic rheology of salt beds and pre-salt faulted anticlinal structure constitute the large wedge-shaped thrust body.The thick delta sandstone of the Cretaceous Bashijike Formation is widely distributed,and it forms the superior reservoir-caprock combination with overlying Paleogene thick gypsum-salt bed.The deep Jurassic-Triassic oil and gas migrate vertically along fault system formed in Late Himalaya,break through the thick Cretaceous mudstone and move laterally along the fracture system of the pre-salt reservoirs,to form anticline and fault anticline high pressure reservoir groups.Through near ten years of studies,the three-dimensional seismic acquisition and processing technology for complex mountainous areas,extrusion salt-related structural modeling technology and fractured low-porosity sandstone reservoir evaluation technology have been established,which lay a foundation for realization of oil and gas exploration objectives.Logging acquisition and evaluation technology for high temperature,high pressure,ultra-deep and low-porosity sandstone gas reservoirs,and efficient development technology for fractured tight sandstone gas reservoirs have been developed,which provide a technical support for efficient exploration&development and rapid production of the Keshen gas field.

Twenty-three new spider species(Arachnida:Araneae)from Asia

A new genus,Sinophaena Lin&Li,gen.nov.,of the spider family Anyphaenidae Bertkau,1878 is reported,with S.xiweni Lin&Li,sp.nov.(♀)from Sichuan,China as the type species.Sinophaena bivalva(Zhang&Song,2004)comb.nov.is transferred from Anyphaena Sundevall,1833.Further new species reported in the current paper include:Anyphaena grovyle Lin&Li,sp.nov.(♂♀,Hainan),A.sceptile Lin&Li,sp.nov.(♂♀,Hainan),A.shenzhen Lin&Li,sp.nov.(♂♀,Guangdong),A.tibet Lin&Li,sp.nov.(♂♀,Tibet),A.treecko Lin&Li,sp.nov.(♂♀,Hainan),Cybaeus fushun Lin&Li,sp.nov.(♀,Liaoning),C.huadian Lin&Li,sp.nov.(♀,Jilin),Eresus lishizheni Lin,Marusik&Li,sp.nov.(♂,Xinjiang),Alistra pikachu Lin&Li,sp.nov.(♂♀,Guangdong),Sinopesa gollum Lin&Li,sp.nov.(♂,Guangdong),Pimoa gagna Zhang&Li,sp.nov.(♀,India),P.nainital Zhang&Li,sp.nov.(♂♀,India),P.shoja Zhang&Li,sp.nov.(♂♀,India),Selenops crewsae Lin&Li,sp.nov.(♀,Sichuan),Sinopoda helii Wang&Li,sp.nov.(♂♀,Sichuan),Phlogiellus jiaxiangi Lin&Li,sp.nov.(♂♀,Guangxi),Episinus bonjovi Lin&Li,sp.nov.(♂♀,Yunnan),E.jiangweni Lin&Li,sp.nov.(♂♀,Yunnan),E.tongyani Lin&Li,sp.nov.(♂♀,Yunnan),Meotipa luoqiae Lin&Li,sp.nov.(♂,Yunnan),M.menglun Lin&Li,sp.nov.(♂,Yunnan),and M.zhengguoi Lin&Li,sp.nov.(♂,Yunnan).The female of Belisana yuexiu Yao&Li,2020 is reported for the first time.All types are deposited in the Institute of Zoology,Chinese Academy of Sciences(IZCAS)in Beijing,China.

Taste mechanism of kokumi peptides from yeast extracts revealed by molecular docking and molecular dynamics simulation

Peptides have been used as flavors for decades,however,their tasting mechanism remains not entirely clear.In the present work,10 kokumi peptides identified in yeast extracts were selected as ligands.Their binding mechanism to calcium-sensitive receptors(CaSR)were investigated at molecular level by using molecular docking and molecular dynamics simulations.The results showed that all kokumi peptides could bind to CaSR to form complexes,of whichγ-Glu-Cys-Gly(GSH),γ-Glu-Leu(EL)andγ-Glu-Tyr(EY)being the top 3 peptides with higher affinity.Arg66,Ser147 and Ala168 may be the active sites of CaSR and interact with CaSR through hydrogen bonds;the different kokumi peptides and CaSR mainly rely on hydrogen bonding,electrostatic interaction and hydrophobic interaction to bind each other.This study provides a theoretical reference for the interaction between kokumi peptides and their receptors.