A modified 3D mean strain energy density criterion for predicting shale mixed-mode Ⅰ/Ⅲ fracture toughness

The fracture toughness of rocks is a critical fracturing parameter in geo-energy exploitation playing a significant role in fracture mechanics and hydraulic fracturing.The edge-notched disk bending(ENDB)specimens are employed to measure the entire range of mixed-modeⅠ/Ⅲfracture toughness of Longmaxi shale.To theoretically interpret the fracture mechanisms,this research first introduces the detailed derivations of three established fracture criteria.By distinguishing the volumetric and distortional strain energy densities,an improved three-dimensional mean strain energy density(MSED)criterion is proposed.As the critical volumetric to distortional MSED ratio decreases,the transition from tensiondominated fracture to shear-dominated fracture is observed.Our results indicate that both peak load and applied energy increase significantly with the transition from pure mode I(i.e.,tension)to pure modeⅢ(i.e.,torsion or tearing)since mode-Ⅲcracking happens in a twisted manner and mode-Ⅰcracking occurs in a coplanar manner.The macroscopic fracture signatures are consistent with those of triaxial hydraulic fracturing.The average ratio of pure mode-Ⅲfracture toughness to pure mode-Ⅰfracture toughness is 0.68,indicating that the obtained mode-Ⅲfracture resistance for a tensionbased loading system is apparent rather than true.Compared to the three mainstream fracture criteria,the present fracture criterion exhibits greater competitiveness and can successfully evaluate and predict mixed-modeⅠ/Ⅲfracture toughness of distinct materials and loading methods.

Influence of syngas components and ash particles on the radiative heat transfer in a radiant syngas cooler

Radiant syngas cooler(RSC)is widely used as a waste heat recovery equipment in industrial gasification.In this work,an RSC with radiation screens is established and the impact of gaseous radiative property models,gas components,and ash particles on heat transfer is investigated by the numerical simulation method.Considering the syngas components and the pressure environment of the RSC,a modified weighted-sum-of-gray-gases model was developed.The modified model shows high accuracy in validation.In computational fluid dynamics simulation,the calculated steam production is only 0.63%in error with the industrial data.Compared with Smith's model,the temperature decay along the axial direction calculated by the modified model is faster.Syngas components are of great significance to heat recovery capacity,especially when the absorbing gas fraction is less than 10%.After considering the influence of particles,the outlet temperature and the proportion of radiative heat transfer are less affected,but the difference in steam output reaches 2.7 t·h^(-1).The particle deposition on the wall greatly reduces the heat recovery performance of an RSC.

高校化学药品库安全设施配置的探讨

初步介绍了国内危险化学药品存放相关标准的发展过程,探讨了药品库的安全设施改造。从水电照明设施、监控系统、通风系统三方面出发提出药品库安全设施配置思路;然后根据化学品性质分成常规药品库,易制毒药品库,易制爆药品库,剧毒药品库四种类型,对四个不同类型的药品库提出了安全设施的配置方案,为加强国内高校药品库安全设施建设工作提供借鉴。

电子态调控促进氢气无损耗纯化中CO的光致富集和氧化

随着选择性氧化(PROX)的快速发展,将氢气中残留的微量CO去除以达到质子交换膜燃料电池的使用氢要求,成为氢气纯化中迫切需要解决的问题.光催化氧化可将氢气流中的CO浓度降低至1×10^(-6)以下.本质上,该反应是光生·OH与痕量CO在氢气中反应.在该过程中,虽然·OH会不可避免地与H2发生碰撞而形成氢自由基(·H),但是环境中的H2会与之结合并通过氢交换促进自由基间的有效碰撞而结合成H2,避免氢气损耗.相比于现有的氢气纯化方案,光催化CO氧化可发展成为一种不损耗氢气的纯化技术.该技术虽然具有应用前景,但·OH的非选择性碰撞严重降低了其利用率以及整个氢气无损耗纯化反应过程中的光子利用率,因此,提出可行方案来促进·OH的产生及其与CO的碰撞成为研究重点.本文采用密度泛函理论结会Climbing image-nudged elastic band方法研究水分子在TiO_(2)上的反应过程.在普通TiO_(2)(101)晶面上形成*OH的势垒为0.57eV;而采用Mg来取代TiO_(2)的5c-或者6c-Ti位点后,势垒分别降至0.25和0.2 eV,并且*OH吸附在相邻Ti位点上的自由能比·OH高.除了促进光致·OH的产生,Mg掺杂所形成的位点还能促进发生在半导体-助催化剂界面秒级别的电子转移,进一步提高光子利用率.而且,Mg掺杂降低了TiO_(2)中Ti4+的电子云密度,促进了CO分子中碳5σ轨道上的负电荷转移至半导体阳离子,同时增强了半导体中阴离子向CO分子转移负电荷的能力,由此可以增强所形成的Mg掺杂TiO_(2)(Mg-TiO_(2))与CO的静电作用,实现该气体在半导体附近的富集.因此,Mg掺杂不仅可以促进羟基自由基的产生,还可以通过静电作用促进CO在Mg-TiO_(2)表面的富集,提高自由基对目标反应的碰撞概率.在光催化CO氧化反应中,Mg-TiO_(2)展现出比普通TiO_(2)更优的性能;并且随着CO浓度降低,Mg掺杂带来的CO富集效应愈加显著,进而表现出更好的催化性能.在光催化氢气无损耗纯化反应中,基于Mg-TiO_(2)催化剂的光催化固定床反应可将流速为1 L/min的H2气流中CO/H2的比浓度降低至<1×10^(-6),并展现出高效的光子利用.与其它将CO/H2比浓度降低至10-6的方法相比,本文催化剂气时空速可达600000 h^(-1),远高于PROX的5000 h^(-1)以及CO甲烷化的7500 h^(-1).综上,本工作揭示了电子态调控对CO光致富集和氧化的促进作用,对氢气无损耗纯化的光子利用效率提升和商业化具有借鉴意义.

Influences of regeneration atmospheres on structural transformation and renderability of fluidized catalytic cracking catalyst

The regeneration of fluidized catalytic cracking(FCC)catalysts is an essential process in petroleum processing.The current study focused the regeneration reaction characteristics of spent fluidized catalytic cracking catalyst(SFCC)at different atmospheres with influences on pore evolution and activity,for a potential way to reduce emission,produce moderate chemical product(CO),and maintain catalyst activity.The results show that regeneration in air indicates a satisfaction on removing coke on the catalyst surface while giving a poor effect on eliminating the coke inside micropores.This is attributed that the combustion in air led to a higher temperature and further transformed kaolinite phase to silicaaluminum spinel crystals,which tended to collapse and block small pores or expand large pores,with similar results observed in pure O_(2)atmosphere.Nevertheless,catalysts regenerated in O_(2)/CO_(2)diminished the combustion damage to the pore structure,of which the micro porosity after regeneration increased by 32.4% and the total acid volume rose to 27.1%.The regeneration in pure CO_(2)displayed low conversion rate due to the endothermic reaction and low reactivity.The coexistence of gasification and partial oxidation can promote regeneration and maintain the original structure and good reactivity.Finally,a mechanism of the regeneration reaction at different atmospheres was revealed.

Flavanone and flavonoid hydroxylase genes regulate fiber color formation in naturally colored cotton

Using naturally colored cotton(NCC)can eliminate dyeing,printing and industrial processing,and reduce sewage discharge and energy consumption.Proanthocyanidins(PAs),the primary coloration components in brown fibers,are polyphenols formed by oligomers or polymers of flavan-3-ol units derived from anthocyanidins.Three essential structural genes for flavanone and flavonoid hydroxylation encoding flavanone-3-hydroxylase(F3H),flavonoid 3’-hydroxylase(F3’H)and flavonoid 3’5’-hydroxylase(F3’5’H)are initially committed in the flavonoid biosynthesis pathway to produce common precursors.The three genes were all expressed predominantly in developing fibers of NCCs,and their expression patterns varied temporally and spatially among NCC varieties.In GhF3Hi,GhF3’Hi and GhF3’5’Hi silenced lines of NCC varieties XC20 and ZX1,the expression level of the three genes decreased in developing cotton fiber,negatively correlated with anthocyanidin content and fiber color depth.Fiber color depth and type in RNAi lines changed with endogenous gene silencing efficiency and expression pattern,the three hydroxylase genes functioned in fiber color formation.GhF3H showed functional differentiation among NCC varieties and GhF3’H acted in the accumulation of anthocyanin in fiber.Compared with GhF3’H,GhF3’5’H was expressed more highly in brown fiber with a longer duration of expression and caused lighter color of fibers in GhF3’5’H silenced lines.These three genes regulating fiber color depth and type could be used to improve these traits by genetic manipulation.

Coexisting lattice contractions and expansions with decreasing thicknesses of Cu(100)nano-films

Lattice parameters are a basic quantity in material characterization,and a slight alteration in lattice parameters directly affects the properties of materials.However,there are still considerable controversies as to whether lattice expansion or contraction occurs in metallic nanomaterials with size reduction.Here,the size dependences of the lattice parameter and surface free energy of clean Cu(100)films are investigated via simulations.Lattice parameters of the exposed surfaces contract,whereas lattice expansion occurs along the direction perpendicular to the surfaces with decreasing film thicknesses.This is striking since the metallic bonds usually lack strong directionality,and it is always regarded that the lattice variations in all directions are consistent.The contraction parallel to the surface is more severe than the expansion perpendicular to the surface in films.The lattices change from cubic to tetragonal with decreasing film thickness.Consequently,common contractions and occasional expansions of the lattice parameters of Cu nanoparticles have been observed in previous experiments.Increasing free energy and surface free energy with decreasing thicknesses is the thermodynamic origin of the lattice variations.Our study therefore provides a comprehensive physical basis for the surface effects on the lattice variations.

Outlook of Energy Storage via Large-Scale Entrained-Flow Coal Gasification

1.Introduction The decarbonization of the energy sector,which greatly relies on fossil-fuel energy,requires urgent action on a global scale to reduce carbon emissions to a net-zero state and to mitigate the effects of climate change[1,2].With a multi-level global energy transition already underway,there is an inevitable trend to use renewable energy to replace traditional fossil-fuel energy.

超疏水材料的研究进展

近年来,油水分离技术越来越受到人们的重视,而具有特殊润湿性的油水分离材料成为研究热点。文中综述了超疏水材料在油水分离领域的研究进展。简单地介绍了构建超疏水材料的基本原理,归纳总结了超疏水材料的制备方法如水热法、刻蚀法、静电纺丝技术、自组装技术、溶胶-凝胶法和沉积法等方法,并且讨论了不同方法的优缺点及前景,为今后超疏水材料的发展提供理论建议。

Validation for equation of state in wide regime:Copper as prototype

In this paper we introduce the wide regime equation of state(WEOS)developed in Institute of Applied Physics and Computational Mathematics(IAPCM).A semi-empirical model of the WEOS is given by a thermodynamically complete potential of the Helmholtz free energy which combines several theoretical models and has some adjustable parameters calibrated via some experimental and theoretical data.The validation methods of the equation of state in wide regime are presented using copper as a prototype.The results of the WEOS are well consistent with the available theoretical and experimental data,including ab initio cold curve under compression,isotherm,Hugoniot,off-Hugoniot and sound velocity data.It enhances our confidence in the accuracy of the WEOS,which is very important for the validation and verification of equation of state in high temperature and pressure technology.

Opposed multi-burner gasification technology:Recent process of fundamental research and industrial application

Opposed multi-burner(OMB)gasification technology is the first large-scale gasification technology developed in China with completely independent intellectual property rights.It has been widely used around the world,involving synthetic ammonia,methanol,ethylene glycol,coal liquefaction,hydrogen production and other fields.This paper summarizes the research and development process of OMB gasification technology from the perspective of the cold model experiment and process simulation,pilotscale study and industrial demonstration.The latest progress of fundamental research in nozzle atomization and dispersion,mixing enhancement of impinging flow,multiscale reaction of different carbonaceous feedstocks,spectral characteristic of impinging flame and particle characteristics inside gasifier,and comprehensive gasification model are reviewed.The latest industrial application progress of ultralarge-scale OMB gasifier and radiant syngas cooler(RSC)combined with quenching chamber OMB gasifier are introduced,and the prospects for the future technical development are proposed as well.

Robust online temperature estimation of a membrane-wall gasifier

The gasifier temperature is a key parameter in the operation of a slag-tapping entrained-flow gasifier.However,there is no effective method for measuring the operating temperature of a membrane-wall-lined gasifier.In this study,a novel robust method for estimation of the online temperature was developed for a membrane-wall gasifier and applied in an industrial SE gasifier.The industrial test results show that the method can estimate the gasifier temperature within 0.04 s,and its value can be reliably obtained.Based on the combination of bench-scale gasifier validation,commercial-scale gasifier operation experience,and the comparison of different simulation methods,the proposed method is accurate and reliable for measuring the operating temperature of a membrane-wall-lined gasifier.

Characteristics of single petcoke particle during the gasification process at high temperatures

Particle concentration significantly affected the gasification of petcoke particles according to our previous studies.In this work,gasification characteristics and morphological evolution of single petcoke particle were investigated using a high temperature stage microscope experimental setup.The results showed that the reaction temperature significantly affected the reactivity of petcoke in the temperature range of 1200–1300°C.While the promoting effect on gasification reactivity decreased with further increasing the reaction temperature,the SEM analysis demonstrated the pore development during the gasification process,which attributed to the increase of reaction rate with conversion.The Raman analysis,HRTEM and SEM–EDX analysis showed that the heterogeneous graphitization of petcoke and non-uniform distribution of catalytic elements in petcoke attributed to the development of surface pores with limited depth.The gasification mechanism of petcoke particle can be briefly described as the reaction rate mainly contributed from the fast-reaction area.Besides,the pore development in fast-reaction area also enlarged the surface area of petcoke particle.

The study of the effect of gas-phase fluctuation on slag flow and refractory brick corrosion in the slag tapping hole of an entrained-flow gasifier

The service life of refractory brick in the slag tapping hole of the entrained flow gasifier was significantly lower than that in other locations.It was critically important to study the corrosion mechanism of refractory brick in the slag tapping hole for guiding industrial production.Considering the complex flow field in the slag tapping hole,the influence of gas velocity and temperature fluctuation on the service life of refractory brick was investigated in this study.The results showed that the slag flow characteristics periodically changed with the gas temperature and velocity fluctuations.The brick corrosion rate increased with the decrease of fluctuation frequency.Compared with the gas-phase velocity fluctuation,the gasphase temperature fluctuation had a more significant influence on the brick corrosion rate.When the fluctuation frequency was 0.01 Hz and the gas temperature fluctuation amplitude was 200 K,the corrosion rate of refractory bricks increased by 25%.It could be concluded that the fluctuation of gas-phase temperature was the main cause for the low service life of refractory bricks in the tapping hole.

“翻转课堂”教学法在无机及分析化学课程教学中的实践与效果分析

翻转课堂倡导主动学习,这种线上线下混合式的学习方法广受学生欢迎。翻转课堂主要包括两个部分:第一,学生远离课堂的线上自主学习;第二,互动的、以课堂为基础的鼓励解决问题和体验式的学习活动。以翻转课堂教学法和传统教学法对生物类专业本科一年级学生开展无机及分析化学课程的教学,采用统计分析软件SPSS分析学生的成绩表现和对翻转课堂教学法的满意度。分析结果表明,学生积极参与翻转课堂教学环节,整体成绩得到明显提高,学生对翻转课堂教学法的满意度较高,说明翻转课堂教学法比传统教学法优势明显。

Effect of the projector augmented wave potentials on the simulation of thermodynamic properties of vanadium

We report significant differences in high-pressure properties of vanadium at zero temperature and finite temperature when different projector augmented wave(PAW)potentials are used in simulations based on density functional theory.When a PAW potential with only five electrons taken as valence electrons is used,the cold pressures in the high-pressure region are seriously underestimated,and an abnormality occurs in the melting curve of vanadium at about 400 GPa.We show that the reason for these discrepancies lies in the differences in the descriptions of the interatomic force,electron dispersion,and anisotropy of electron bonding obtained from differentPAWpotentials at high pressure,which lead to striking differences in the mechanical stability of the system.We propose a procedure for selecting PAW potentials suitable for simulations at high temperature and high pressure.Our results provide valuable guidance for future simulations of thermodynamic properties under extreme conditions.

First-principles study on the mechanical properties and thermodynamic properties of Mo-Ta alloys

The mechanical properties,thermodynamic properties and electronic structure of Mo1-xTax(Mo-Ta)alloys(x=0,0.0625,0.125,0.25,0.3125,0.5 and 1)were calculated by using firstprinciples.The electronic structure of Mo-Ta alloys was analysed by the projected density of states(PDOS).The low temperature heat capacity was estimated by Fermi energy and Debye temperature.It is shown that the formation enthalpy will decrease with the increase of Ta content,and the cohesive energy will increase with the increase of the Ta content.On the other hand,the addition of Ta atoms will reduce the strength and improve the ductility of Mo-Ta alloys,the Debye temperature will decrease and the low temperature heat capacity will be improved with the increase of the Ta content.All these results will be useful for the research of new plasma grid(PG)materials,which is mainly used in neutral beam injection(NBI)systems to produce negative hydrogen ions.

First-principles study on the electronic structure transition ofβ-UH3 under high pressure

We investigate the electronic properties of stableβ-UH3 under high pressure up to 75 GPa within the first-principles DFT+U formalism with pressure-dependent U in a self-consistent calculation,and we find an electronic structure transition at about 20 GPa due to the quantum process of localization and itinerancy for partially filled uranium 5f electrons.The electronic structure transition is examined from four perspectives:magnetization,band structure,density of states,and 5f electron energy.On the basis of the density of states of 5f electrons,we propose an order parameter,namely,the 5f electron energy,to quantify the electronic structure transition under pressure.Analogously to the isostructural transition in 3d systems,β-UH3 retains its magnetic order after the electronic structure transition;however,this is not accompanied by volume collapse at the transition point.Our calculation is helpful for understanding the electronic properties ofβ-UH3 under high pressure.

Analysis on the clinical and endoscopic parameters in 1247 patients with reflux esophagitis

Aim: To summarize and analyze the clinical and endoscopic parameters in patients with reflux esophagitis(RE). Methods:1247 patients with RE were diagnosed in our hospital endoscopy center from September 2010 to August 2012. The general information of the patients and the relationship between endoscopic classification and concomitant diseases were analyzed. Results: According to the endoscopic findings, 1247 subjects (4.70%) were found to have RE:932 (74.74%) males and 315 (25.26%) females, and the male to female ratio was 2.96:1. The peak age of prevalence was 50 to 59 (27.35%) which is followed by 40 to 49 (23.10%). In this study, most of the patients had a mild degree of esophagitis representing LA-A in 60.63% and LA-B in 34.24%. The antrum hyperemia was found in 291 patients with esophagitis (23.34%), followed by antrum erosion (20.13%) and hatal hernia (15.88%). There is no statistically significant relevance between Helicobacter pylori infection and RE (P > 0.05), but Barrett’s esophagus, duodenal ulcer, gastroesophageal tumors, a history of gastroesophageal surgery and antrum hyperemia were found to be associated with RE (P . Conclusion: The prevalence rate of endoscopic RE in our study was 4.70%, and most patients had a mild grade esophagitis. Male, advanced age, Barrett’s esophagus, duodenal ulcer, gastroesophageal tumors and a history of gastroesophageal surgery are the risk factors of esophagitis. Antrum hyperemia may reduce the severity of RE.

城市精明增长评估体系的设计与应用——以敦煌市为例

城市精明增长理论是城市可持续发展理论的重要延续,对我国城市发展具有重要的战略意义。城市精明增长方案的设计与优化可以使其有限资源产生的效益最大化。本文首先基于城市精明增长准则建立城市精明增长多指标综合评价体系,进而使用熵值法对评估模型中各因素进行赋权,随后对甘肃敦煌市2010~2015年六年的城市发展状况的精明增长指数SMI进行评估。最后,借助灰色关联模型对敦煌市城市总体规划(2013~2030)中2018~2023年的六年城市增长计划进行量化评估并给出相关规划的优化建议。