Two-dimensional material separation membranes for renewable energy purification, storage, and conversion

The current energy crisis has prompted the development of new energy sources and energy storage/conversion devices. Membranes, as the key component, not only provide enormous separation potential for energy purification but also guarantee stable and high-efficiency operation for rechargeable batteries and fuel cells. Remarkably, two-dimensional(2D) material separation membranes have attracted intense attention on their excellent performance in energy field applications, owing to high mechanical/chemical stability, low mass transport resistance, strict sizeexclusion, and abundant modifiable functional groups. In this review, we concentrate on the recent progress of 2D membrane and introduce 2D membranes based on graphene oxide(GO), MXenes, 2D MOFs, 2D COFs, and 2D zeolite nanosheets, which are applied in membrane separation(H2 collection and biofuel purification) and battery separators(vanadium flow battery, Li–S battery, and fuel cell). The mass transport mechanism, selectivity mechanism, and modification methods of these 2D membranes are stated in brief, mainly focusing on interlayer dominant membranes(GO and MXenes) and pore dominant membranes(MOFs, COFs, and zeolite nanosheets). In conclusion, we highlight the challenges and outlooks of applying 2D membranes in energy fields.

A Lagrangian criterion of unsteady flow separation for two-dimensional periodic flows

The present paper proposes a Lagrangian criterion of unsteady flow separation for two-dimensional periodic flows based on the principle of weighted averaging zero skin-friction given by Haller （HALLER, G. Exact theory of unsteady separation for two-dimensional flows. Journal of Fluid Mechanics, 512, 257-311 （2004））. By analyzing the distribution of the finite-time Lyapunov exponent （FTLE） along the no-slip wall, it can be found that the periodic separation takes place at the point of the zero FTLE. This new criterion is verified with an analytical solution of the separation bubble and a numerical simulation of lid-driven cavity flows.

Two-dimensional graphitic carbon nitride for membrane separation

Recent years,membrane separation technology has attracted significant research attention because of the efficient and environmentally friendly operation.The selection of suitable materials to improve the membrane selectivity,permeability and other properties has become a topic of vital research relevance.Two-dimensional(2D)materials,a novel family of multifunctional materials,are widely used in membrane separation due to their unique structure and properties.In this respect,as a novel 2D material,graphitic carbon nitride(g-C_(3)N_(4))have found specific attention in membrane separation.This study reviews the application of carbon nitride in gas separation membranes,pervaporation membranes,nanofiltration membranes,reverse osmosis membranes,ion exchange membranes and catalytic membranes,along with describing the separation mechanisms.

USING TWO-DIMENSIONAL TIME RESOLVED LIGHT SCATTERING TO STUDY THE CURE REACTION INDUCED PHASE SEPARATION PROCESS OF EPOXY-AMINE-POLYETHERSULFONE BLEND WITH SECONDARY PHASE SEPARATION

The generalized two-dimensional correlation analysis based on time-resolved light scattering patterns （2D TRLS） has been employed to study the phase separation process of an epoxy-amine-polyethersulfone blend in which the secondary phase separation takes place. The results of the 2D TRLS provided more detailed information that was not readily observed in the 1D TRLS patterns. （i） During the first process of phase separation, the sequential order of coarsening in size of the domains among the larger and smaller ones has been reversed between the diffusion regime and the hydrodynamic regime. （ii） The change of the larger domains in size, due to the hydrodynamic flow in the late stage of the first phase separation process, keeps on taking place earlier than that of the new domains appeared in the secondary phase separation process. （iii） During the secondary phase separation process the size growth of the smaller domains takes place earlier than that of the larger ones, probably due to the assumption that the coarsening mode could decrease the interface tension more quickly.

FAST SOLUTION OF TURBULENT SEPARATION BY STRAWN'S METHOD

A quasi-simultaneous viscous/inviscid interaction model and a new integral method are tried to predict twodimensional incompressible turbulent boundary-layer separating flows. The results are compared with experiments and other prediction.

考虑系统振动的电主轴回转误差检测方法研究

针对目前机床主轴的回转精度检测不能反映主轴在切削工况下的实际回转精度、现有三点法检测的主轴回误差信号包含了系统振动信号的问题,在传统三点法的基础上加入振动加速度传感器,实时测量系统的振动加速度,进而提出一种包含系统振动信号分离的新型三点法。首先,通过建立考虑系统振动的回转误差检测数学模型,得到系统的振动位移和传感器相对主轴的绝对位移;其次,采用误差分离技术,得到主轴在切削工况下的实际回转误差;最后,研制出一套主轴在切削工况下的回转误差检测装置并进行了实验验证。研究结果表明,所提出方法能有效提高主轴在切削工况下回转误差的检测精度。

基于改进保守凸可分近似的高超声速飞行器轨迹规划方法

面向高超声速飞行器轨迹在线规划需求,提出一种改进的保守凸可分近似规划方法,以解决当前序列凸优化的振荡不收敛问题。首先,基于序列凸化、松弛变量、罚函数等方法将高超声速飞行器轨迹规划这一非凸原问题转化为凸的子问题。其次,针对凸优化中的振荡不收敛问题,设计一种使迭代序列趋于聚点的信赖域更新策略,并验证该策略能有效避免迭代中后期进程缓慢的“振荡现象”。进一步地,结合改进的信赖域更新策略,提出基于改进保守凸可分近似的轨迹规划方法,并对算法进行等效性和收敛性分析,证明该算法能够收敛到原问题的一个驻点。最后,以复杂约束条件下的高超声速飞行器轨迹规划问题为例,对随机初始猜测值和随机终点两种工况进行仿真验证,并与序列二次规划方法的规划结果进行对比,结果表明本文算法在满足求解精度的要求下,具有较快的求解速度、以及较好的收敛性和鲁棒性。

在线脱醚在氧化工艺环己酮装置中的应用

环己酮是生产尼龙、己内酰胺、己二酸、香料、医药、树脂等化工产品的原料,作为溶剂广泛用于涂料、染料、油漆、农药、橡胶、印刷和塑料的回收等方面。按原料不同,工业生产环己酮的方法主要有苯酚加氢法、环己烯水合法以及环己烷氧化法。氧化工艺环己酮装置在环己烷与氧气高温氧化过程中,会生成副产物丁基环己基醚等,该类物质沸点与目标产物环己醇相差不大,因而在后续真空精馏中难以除去,也不参与环己醇脱氢反应,作为惰性物质在系统内循环累积,浓度不断上涨,影响环己酮装置精馏工序的分离效果和脱氢反应过程。某公司环己酮装置在国内首次运行在线脱醚技术,成功将系统内醚含量脱除至1.7%以下,且能在长周期维持系统内低醚含量,降低装置运行能耗,对国内环己酮行业有较强的指导意义。

五举煤业实现煤质创效的应用实践

为解决升井原煤煤质差,煤质检测存在滞后性,影响选煤厂生产效率及产品质量的问题,基于对原煤开采、运输及洗选加工各环节的分析,通过采取降低工作面采高,建设井下TDS智能干选预排矸系统,采用自动采制样、煤质在线检测,对煤质进行信息化、数字化管理等措施,实现对煤炭质量的精准控制和预警。实践表明,以上措施采用后,升井原煤灰分平均降低15个百分点,洗选精煤灰分波动小于0.3个百分点,精煤产率达到35%以上。通过实施全过程煤质控制,降低了生产成本,减少了环境污染,提高了企业的经济效益和社会效益,可为其他存在类似问题的选煤厂提供一定借鉴。

Double Off-line Two-dimensional Liquid Chromatography for Separation and Identification of Compounds in Salvia Miltiorrhiza(Danshen)

Background: Danshen is an important traditional Chinese medicine(TCM) used for the treatment of cardiovascular and cerebrovascular diseases. Separation and analysis of its components have been widely investigated. However, the systematical two dimensional liquid chromatography(2D-LC) methods have not been developed to comprehensively separate and characterize its components.Objective: In this work, double off-line 2D-LC methods were aimed to develop for the systematical separation of compounds from Danshen.Methods: Using solid phase extraction(SPE), the Danshen extract was divided into a medium-polar fraction(Sample I) and a weak-polar fraction(Sample Ⅱ) according to their polarities. Based on reversed-phase liquid chromatography(RPLC) and hydrophilic interaction liquid chromatography(HILIC) modes, a 2D-HILIC × RPLC system and a 2D-RPLC × RPLC system were designed for the separation of Sample Ⅰ and Sample Ⅱ, respectively. According to reversed-phase and HILIC columns selectivities characterized in our previous reports, ZIC-HILIC and XTerra C18 were employed to build the 2D-HILIC × RPLC system and Click TE-CD and XTerra C18 for the 2D-RPLC × RPLC system,respectively.Results: The 2D-HILIC × RPLC and 2D-RPLC × RPLC systems exhibited excellent orthogonality for the separation of Sample Ⅰ and Sample Ⅱ,respectively. Their orthogonalities were 88.42% and 63.24%. Based on these double 2D-LC systems combined with mass spectrometry, at least 200 compounds were found and 33 compounds of them were identified, including 16 phenolic acids and 17 diterpenoid quinines.Conclusion: These results suggest that these two off-line 2D-LC methods are effective for the separation and characterization of components in Danshen.

Two-dimensional cobalt metal-organic frameworks for efficient C_3H_6/CH_4 and C_3H_8/CH_4 hydrocarbon separation

A Co-based two-dimensional（2 D） microporous metal-organic frameworks, [Co2（TMTA）（DMF）2（H2O）2]·NO3-·DMF（UPC-32） has been synthesized based on 4,4’,4’’-（2,4,6-trimethylbenzene-1,3,5-triyl）tribenzoic acid（H3TMTA）. UPC-32 features a 2 D microporous framework exhibits high adsorption of H2（118.2 cm3/g, 1.05 wt%, at 77 K）, and adsorption heat（Qst） of CO2（34–46 k J/mol）. UPC-32 with narrow distance between layers（3.8 ？） exhibits high selectivity of C3H6/CH4（31.46） and C3H8/CH4（28.04） at298 K and 1 bar. It is the first 2 D Co-MOF that showed selective separation of C3 hydrocarbon from CH4.

Two-dimensional correlation analysis of continuous online in situ ATR-FTIR on the adsorption of butyl xanthate at the surface of α-PbO

The adsorption behavior of butyl xanthate on the surface of lead oxide was investigated using continuous online in situ attenuated total reflectance Fourier transform infrared（ATR-FTIR） spectroscopy technique and two dimensional（2D） correlation analysis.The adsorbed layer studied was prepared by coating α-PbO particles onto the surfaces of the ZnSe crystal.The appearance of spectral peaks at 1203 cm^-1,1033 cm^-1 and their red shift indicated the formation and aggregation of xanthate at the surface of α-PbO.According to 1R intensity changes after rinsing with deionized water and a NaOH solution,the adsorption was proved to be a chemisorption type.The competition between xanthate and OH^- for the surfaces leads to desorption of xanthate at higher pH.The technique of 2D correlation ATR-FTIR spectroscopy was used to evaluate the changing order of spectral intensities in the adsorption process,and the results indicated that xanthate micelles were formed at the surfaces.The adsorption kinetics of butyl xanthate was found to be a pseudo-second-order reaction model and the adsorption capacity of butyl xanthate at α-PbO was as high as 281 mg g^-1 after 150 min.

在线诉讼中民事证据运用的碎片化问题及其纾解之道

2021年修改通过的《中华人民共和国民事诉讼法》第16条规定了在线诉讼的“等效原则”,赋予了所有在线诉讼活动合法性。然而,通过问卷调查、交流访谈与案例检索等实证研究发现,我国在线诉讼中民事证据运用存在碎片化问题,具体表现为:认知层面对在线诉讼存在误解,规范层面法律规范供给不足且不均,实践层面存在证据原件原物提交“时间差”、举证与质证“去剧场化”及证据信息安全伴随“高风险”等。碎片化问题的成因在于:传统纠纷解决观念与多元司法服务观念间的矛盾、“等效原则”抽象规范供给与在线诉讼具体实践需求间的矛盾、平台建设供给与司法实践需求间的矛盾。我们需要在理念层面树立以人民为中心的在线诉讼服务理念,在规范层面完善在线诉讼证据规则,在实践层面创建取证、传递、质证互联统一且安全的证据平台,从而有效纾解在线诉讼中民事证据运用的碎片化问题,促进在线诉讼的可持续发展。

《化工分离过程》“线上线下”混合课程建设与探索

为了落实目标导向的教学理念,激发学生的学习兴趣和学习主动性,更好的达成教学目标,《化工分离过程》课程进行了“线上线下”混合课程的建设与实践探索。课程在教学目标、课程教学策略、评价与反馈、学习支持等方面进行综合课程设计,以确保课程具有足够的挑战度,从而使得学生能够在整个学期中努力学习,并最终达成教学目标。课程改革前后的课程目标达成情况对比表明混合式教学改革取得了积极成效。

基于Vue的在线考试系统设计与实现

在线考试系统的实现对教师掌握学生的学习情况及学习巩固知识具有重要意义。文章在分析用户在线考试需求的基础上,设计和开发了一款能同时在PC端和移动端运行且符合用户操作习惯的轻量级在线考试系统。该系统基于前后端分离的思想,采用Vue框架构建和JSON数据交换格式,使用Node.js+json-server作为系统数据的存储和管理技术,实现用户在线考试功能,包括练习测试、收藏集合、错题集合、答题排行等功能模块。测试结果表明该系统在移动端通过网址就能自适应运行,且相比传统技术开发的在线考试系统成本低、运行效率高。

基于SpringBoot+Vue的在线考试系统设计与实现

随着互联网技术的不断发展,在线考试模式得到了更为广泛的应用,为满足教师和学生对于快捷出题、快速批改、诚信考试的需求,文章基于前后端分离的思想,前端使用Vue技术搭建,后台采用SpringBoot+MybatisPlus,开发一个基于B/S模式的在线考试系统。系统实现单选、多选、判断、填空等题型的自动判分,并且提供主观题错题解析、错题集合等功能。系统安全稳定、成本低、运行效率高。

油田三相分离器排泥在线旋流预处理工业试验

基于湍动脱附技术与旋流聚结分离技术,提出一种针对新疆油田生产工况的在线处理系统并开展了预处理工业试验。试验结果表明:在处理量7.5 m^(3)/h、溢流率10%、未添加化学助剂条件下,污泥减排率与原油回收率分别可达96.60%、99.30%,排泥含油率可降低至2.04%。试验结果验证了湍动脱附技术与旋流聚结分离技术可联合应用于罐底油泥在线减量化领域,为罐底油泥在线预处理工艺的工业化应用提供了重要理论依据。

基于改进反向可达集的在线社交网络不良信息抑制方法

随着互联网的发展,网络中不良信息的数量呈现出快速增长的趋势,对于社会的稳定与安全构成了威胁.传统的在线社交网络不良信息抑制方法存在效率低、实时性差等问题,为此提出一种基于改进反向可达集的在线社交网络不良信息抑制方法.分析现有的网络不良信息抑制方法,介绍了反向可达集的概念和原理,基于六度分隔理论,提出一种改进反向可达集的生成方法,并进一步提出一种不良信息抑制方法IRRIMM.通过在真实的社交网络数据集中的实验验证了所提出方法的有效性.

基于新浪微博的学校网络舆情系统设计与实现

大数据背景下,构建网络舆情系统能有效、及时地对舆情进行监督和引导。利用Python Django+Vue前后端分离技术方案搭建基于B/S的网络舆情系统。服务器端采用Scrapy框架爬取新浪微博的学校舆情数据,数据预处理后进行情感倾向分析;客户端展示网络舆情分析的结果。系统具有扩展性强、操作简单等特点,解决了学校网络舆情监管问题。

在线固相萃取/二维液相色谱法检测婴幼儿配方食品中视黄醇顺反异构体和α-生育酚手性异构体

建立了在线固相萃取/二维液相色谱分离检测婴幼儿配方食品中全反式视黄醇、13-顺式视黄醇和α-生育酚手性异构体的方法。样品经皂化,定容、离心、过滤后进样,经二乙烯基苯与N-乙烯基吡咯烷酮大孔共聚物(HLB)在线固相萃取柱在线净化后,通过切换阀将视黄醇、4种生育酚洗脱至一维色谱柱五氟苯基填料柱(PFP),在一维色谱柱中实现总视黄醇和4种生育酚异构体的分离。再通过捕集柱与中心切换阀将总视黄醇和α-生育酚切割至二维色谱柱,在3,5-二甲基苯基氨基甲酸酯涂敷的手性色谱柱(CND)上实现了全反式与13-顺式视黄醇的异构体分离,以及α-生育酚的d、l手性异构体分离。采用紫外和荧光检测器检测,外标法定量。结果表明:全反式视黄醇、13-顺式视黄醇的线性范围为0.1~5.0 mg/L,d-α-生育酚、l-α-生育酚的线性范围为1.0~30.0 mg/L,相关系数均大于0.999,定量下限分别为53μg/100 g、56μg/100 g、290μg/100 g和340μg/100 g;低、中和高3个加标浓度下的回收率为90.9%~106%,相对标准偏差(RSD)不大于2.8%。该方法可用于乳基婴幼儿配方食品中视黄醇和α-生育酚的检测及其生物有效性评价。