城市新区极端雨洪汇流淹没特性与致灾机理调查研究——以郑州“7.20”特大暴雨(郑东新区)为例

近年来全球极端暴雨发生的可能性与不确定性提高,增加了城市遭遇特大洪涝灾害的风险。城市雨洪与河道洪水有显著差异,灾后雨洪信息快速采集与调研对认清雨洪特性与致灾机理尤显重要。本文以郑州2021年“7.20”特大暴雨为例,结合郑东新区地理与社会环境特点,采用野外调查测量、口述记录、多源数据分析、数值模拟对比相结合的方法开展了城市雨洪汇流淹没特性及致灾机理的调查研究。针对城市雨洪洪痕特征,拟定调查基本方法与适宜工作程序,根据调查区93处洪痕数据绘制了区域雨洪淹没分布图,分析了城市雨洪峰值水位分布特征及调查区汇流特性,探索了道路雨洪汇流流速及行洪道路阻力参数的确定方法。研究表明,城市雨洪地表主要泄流通道是街区道路,汇流方向受连续阻水、导水建筑与路网布局影响,雨洪淹没深度分布与下垫面条件和雨洪汇流特性有关。致灾机理研究分析表明,极端暴雨汇流远超城市排水管网泄流能力,雨洪选择阻力小的街道快速行洪,街道交汇处壅阻引起局部积水严重,这是极端暴雨致灾的直接诱因;而城市新区水系泄洪排涝关系不协调以及清障不力,导致城区河流行洪不畅,干支流异常高水位的顶托,严重降低了管网排涝功能,则是城市雨洪严重积涝致灾的深层原因。研究成果可为城市雨洪调查标准方法的建立与城市新区防洪排涝体系规划提供技术参考。

Oxidation behavior and improvement in nonflammability of LPSO-type Mg–Zn–Y–Sr alloy

Mg_(97)Zn_(1)Y_(2)alloys with high ignition temperatures were developed by adding Sr.The addition of Sr resulted in the formation of a uniform and thin Y_(2)O_(3)film.Mg–Zn–Y alloys containing at least 0.25 at.%Sr exhibited ignition temperatures of 1270–1320 K.As a result of EDS measurement,Sr was found to be concentrated in the Y_(2)O_(3)film.In addition,a mixed film of MgO and Sr O formed on the outer layer in the 1.5 at.%Sr-containing Mg_(97)Zn_(1)Y_(2)alloy.These findings suggest that the uniform and thin Y_(2)O_(3)film that maintains high soundness at high temperatures was formed owing to valence control and the formation of a protective outer oxide film.

High temperature deformation and recrystallization behavior of magnesium bicrystals with 90°<1010>and 90°<1120>tilt grain boundaries

The deformation mechanisms and dynamic recrystallization(DRX)behavior of specifically grown bicrystals with a symmetric 90°<1010>and 90°<1120>tilt grain boundary,respectively,were investigated under deformation in plane strain compression at 200℃and 400℃.The microstructures were analyzed by panoramic optical microscopy and large-area electron backscatter diffraction(EBSD)orientation mapping.The analysis employed a meticulous approach utilizing hundreds of individual,small EBSD maps with a small step size that were stitched together to provide comprehensive access to orientation and misorientation data on a macroscopic scale.Basal slip primarily governed the early stages of deformation at the two temperatures,and the resulting shear induced lattice rotation around the transverse direction(TD)of the sample.The existence of the grain boundary gave rise to dislocation pile-up in its vicinity,leading to much larger TD-lattice rotations within the boundary region compared to the bulk.With increasing temperature,the deformation was generally more uniform towards the bulk due to enhanced dislocation mobility and more uniform stress distribution.Dynamic recrystallization at 200℃was initiated in{1011}-compression twins at strains of 40%and higher.At 400℃,DRX consumed the entire grain boundary region and gradually replaced the deformed microstructure with progressing deformation.The recrystallized grains displayed characteristic orientations,such that their c-axes were perpendicular to the TD and additionally scattered between 0°and 60°from the loading axis.These recrystallized grains displayed mutual rotations of up to 30°around the c-axes of the initial grains,forming a discernible basal fiber texture component,prominently visible in the{1120}pole figure.It is noteworthy that the deformation and DRX behaviors of the two analyzed bicrystals exhibited marginal variations in response to strain and deformation temperature.

5-Fluorouracil dose escalation generated desensitized colorectal cancer cells with reduced expression of protein methyltransferases and no epithelial-to-mesenchymal transition potential

Background:Colorectal cancer(CRC)is one of the most frequently diagnosed cancers.In many cases,the poor prognosis of advanced CRC is associated with resistance to treatment with chemotherapeutic drugs such as 5-Fluorouracil(5-FU).The epithelial-to-mesenchymal transition(EMT)and dysregulation in protein methylation are two mechanisms associated with chemoresistance in many cancers.This study looked into the effect of 5-FU dose escalation on EMT and protein methylation in CRC.Materials and Methods:HCT-116,Caco-2,and DLD-1 CRC cell lines were exposed to dose escalation treatment of 5-FU.The motility and invasive potentials of the cells before and after treatment with 5-FU were investigated through wound healing and invasion assays.This was followed by aWestern blot which analyzed the protein expressions of the epithelial marker E-cadherin,mesenchymal marker vimentin,and the EMT transcription factor(EMTTF),the snail family transcriptional repressor 1(Snail)in the parental and desensitized cells.Western blotting was also conducted to study the protein expressions of the protein methyltransferases(PMTs),Euchromatic histone lysine methyltransferase 2(EHMT2/G9A),protein arginine methyltransferase(PRMT5),and SET domain containing 7/9(SETD7/9)along with the global lysine and arginine methylation profiles.Results:The dose escalation method generated 5-FU desensitized CRC cells with distinct morphological features and increased tolerance to high doses of 5-FU.The 5-FU desensitized cells experienced a decrease in migration and invasion when compared to the parental cells.This was reflected in the observed reduction in E-cadherin,vimentin,and Snail in the desensitized cell lines.Additionally,the protein expressions of EHMT2/G9A,PRMT5,and SETD7/9 also decreased in the desensitized cells and global protein lysine and arginine methylation became dysregulated with 5-FU treatment.Conclusion:This study showed that continuous,dose-escalation treatment of 5-FU in CRC cells generated 5-FU desensitized cancer cells that seemed to be less aggressive than parental cells.

In-situ study of the microstructure evolution during tension of a Mg-Y-Zn-Al alloy processed by rapidly solidified ribbon consolidation technique

Mg-Y-Zn-Al alloys processed by rapidly solidified ribbon consolidation(RSRC)technique exhibit an exceptional mechanical performance indicating promising application potential.This material has a bimodal microstructure consisting of fine recrystallized and coarse non-recrystallized grains with solute-rich stacking faults forming cluster arranged layers(CALs)and nanoplates(CANaPs),or complete long period stacking ordered(LPSO)phase.In order to reveal the deformation mechanisms,in-situ synchrotron X-ray diffraction line profile analysis was employed for a detailed study of the dislocation arrangement created during tension in Mg-0.9%Zn-2.05%Y-0.15%Al(at%)alloy.For uncovering the effect of the initial microstructure on the mechanical performance,additional samples were obtained by annealing of the as-consolidated specimen at 300 and 400℃ for 2 h.The heat treatment at 300℃ had no significant effect on the initial microstructure,its evolution during tension and,thus,the overall deformation behavior under tensile loading.On the other hand,annealing at 400℃ resulted in a significant increase of the recrystallized grains fraction and a decrease of the dislocation density,leading to only minor degradation of the mechanical strength.The maximum dislocation density at the failure of the samples corresponding to the plastic strain of 10-25% was estimated to be about 16-20×10^(14)m^(-2).The diffraction profile analysis indicated that most dislocations formed during tension were of non-basal and pyramidal types,what was also in agreement with the Schmid factor values revealed independently from orientation maps.It was also shown that the dislocation-induced Taylor hardening was much lower below the plastic strain of 3% than above this value,which was explained by a model of the interaction between prismatic dislocations and CANaPs/LPSO plates.

Hand Cooling Enhances the Proprioceptive Drift during Rubber Hand Illusion

Background: The neural representation of the body is easily altered by integrating multiple sensory signals in the brain. The “Rubber Hand Illusion” (RHI) is one of the most popular experimental paradigms to investigate this phenomenon. During this illusion, ownership of a rubber hand is temporarily induced. It was shown that external and continuous cooling of the palm enhanced the RHI, suggesting an association between altered the autonomic nervous system regulation and altered the sense of ownership of a specific limb. Purpose: To investigate whether artificially cooling the entire hand for a short period affects the magnitude of the illusion. Methods: Participants immersed their entire hand in cool, cold, or warm water for 1 min before the RHI procedure. Results: We found that cooling the entire hand enhanced the proprioceptive drift during the RHI but not the subjective feeling of ownership. In contrast, warming and intense cooling of the entire hand did not affect the RHI strength. Conclusion: Our results suggest that transient and moderate cooling of the entire hand was sufficient in enhancing the illusory disembodiment of one’s own hand.

Interleukin-1β:Friend or foe for gastrointestinal cancers

Gastrointestinal(GI)cancer is a malignancy arising in the digestive system and accounts for approximately a third of increasing global cancer-related mortality,especially in the colorectum,esophagus,stomach,and liver.Interleukin-1β(IL-1β)is a leukocytic pyrogen recognized as a tumor progression-related cytokine.IL-1βsecretion and maturation in inflammatory responses could be regulated by nuclear factor-kappaB-dependent expression of NLR family pyrin domain containing 3,inflammasome formation,and activation of IL-1 converting enzyme.Several studies have documented the pro-tumorigenic effects of IL-1β in tumor microenvironments,promoting proliferation and metastatic potential of cancer cells in vitro and tumorigenesis in vivo.The application of IL-1β inhibitors is also promising for targeted therapy development in some cancer types.However,as a leukocytic pro-inflammatory cytokine,IL-1β may also possess anti-tumorigenic effects and be type-specific in different cancers.This editorial discusses the up-to-date roles of IL-1β in GI cancers,including underlying mechanisms and down-stream signaling pathways.Understanding and clarifying the roles of IL-1β would significantly benefit future therapeutic targeting and help improve therapeutic outcomes in patients suffering from GI cancer.

Lithium Ion Transport Environment by Molecular Vibrations in Ion-Conducting Glasses

Controlling Li ion transport in glasses at atomic and molecular levels is key to realizing all-solid-state batteries,a promising technology for electric vehicles.In this context,Li_(3)PS_(4)glass,a promising solid electrolyte candidate,exhibits dynamic coupling between the Li^(+)cation mobility and the PS_(4)^(3-)anion libration,which is commonly referred to as the paddlewheel effect.In addition,it exhibits a concerted cation diffusion effect(i.e.,a cation-cation interaction),which is regarded as the essence of high Li ion transport.However,the correlation between the Li^(+)ions within the glass structure can only be vaguely determined,due to the limited experimental information that can be obtained.Here,this study reports that the Li ions present in glasses can be classified by evaluating their valence oscillations via Bader analysis to topologically analyze the chemical bonds.It is found that three types of Li ions are present in Li_(3)PS_(4)glass,and that the more mobile Li ions(i.e.,the Li3-type ions)exhibit a characteristic correlation at relatively long distances of 4.0-5.0A.Furthermore,reverse Monte Carlo simulations combined with deep learning potentials that reproduce X-ray,neutron,and electron diffraction pair distribution functions showed an increase in the number of Li3-type ions for partially crystallized glass structures with improved Li ion transport properties.Our results show order within the disorder of the Li ion distribution in the glass by a topological analysis of their valences.Thus,considering the molecular vibrations in the glass during the evaluation of the Li ion valences is expected to lead to the development of new solid electrolytes.

The Impact of Family Relationships on the Smoking Habits of University Students

Smoking habits are thought to be strongly impacted by family relationships. In this study, we looked specifically at family relationships with the aim of finding effective anti-smoking education measures. We surveyed 290 university students in order to establish their current smoking habits, along with their family relationships from primary and junior high school until now. The results showed that students with one or more smokers in their family were clearly more likely to smoke. Furthermore, a poor relationship between the student’s parents and a poor relationship with his/her father are believed to have a causal relationship with the student smoking. In the section in which students were asked how often they were told to study, we found that students who smoked had been instructed to study a significantly higher number of times. It is believed that the stress experienced by students frequently told that they must study during their elementary or junior high school years leads to a tendency to smoke. Among the group of non-smokers, we found many who ate breakfast with their parents during elementary or junior high school, along with many who regularly went on holidays with their families. The lack of these things appears to distance parents from children and may be a factor regarding why children end up smoking. In this study, while no clear correlation was found between family relationships and smoking, several types of family relationships that may lead to smoking were suggested.

Association between the Way of Being Scolded and Self-Esteem in University Students

Self-esteem is an important factor in the rise of depression cases among children and adolescents. In order to build self-esteem, it is important for parents to respect their children, acknowledge their value, and always encourage them, as well as for teachers to acknowledge their character and ability, in addition to allowing them to experience success. At the same time, voices calling for parents and teachers to rediscover their willingness and responsibility to scold children when necessary have also been growing. Therefore, the objective of the present study was to determine the association between self-esteem and the way of scolding. With 311 university students as the study subjects, self-esteem and the relevant factors thereof were evaluated. As a result, no association was observed between the way of being scolded and self-esteem. Moreover, the reasons for being scolded were also not associated with self-esteem. However, regarding the association between the degree of acceptance (convinced by the way of being scolded) and self-esteem, it was revealed that student groups with higher self-esteem had a higher degree of acceptance. This suggested that self-esteem is associated with whether or not the people being scolded are convinced, as opposed to the way of being scolded or the reason for being scolded. Therefore, it was suggested that building a good relationship with those you scold is more important than the way of scolding.

Investigation of Prefrontal Cortex Activity in University Students with Presenteeism: A Near-Infrared Spectroscopy (NIRS) Study

Presenteeism refers to impaired performance attributed to attending work with health problems. There has been no study examining the state of presenteeism with objective measures. We compared cerebral hemodynamic changes, measured by near-infrared spectroscopy (NIRS), during neuropsychological tests conducted by university students with presenteeism and healthy controls. Twenty-two university students participated in the study;11 of them with impaired performance caused by mental health problem were allocated to the presenteeism group and 11 without health problems to the control group. Presenteeism was assessed by the Presenteeism Scale for Students. To evoke hemodynamics changes, the participants completed a Word Fluency Test (WFT) and a Trail Making Test (TMT). The NIRS probes were located over the bilateral prefrontal area. Students with presenteeism had significantly higher incidences of depression than controls. However, there was no significant difference in behavioral performance examinations between the two groups. With regard to hemodynamics changes, the repeated measures analysis of covariance of the NIRS signals revealed significant interactions between group and task activation. Although we observed a significant increase in oxygenated hemoglobin concentration during the WFT among controls (simple main effect;left channel, F(1, 19) = 27.34, P F(1, 19) = 22.05, P < 0.001), no changes were found in students with presenteeism during either the WFT (simple main effect;left channel, F(1, 19) = 0.12, P F(1, 19) = 0.08, P t = ﹣0.94, P with Bonferroni correction = 0.745;right channel, t = ﹣2.19, P with Bonferroni correction < 0.113). This is the first study to reveal differences in activity in the cerebral cortex associated with presenteeism. The fact that students with presenteeism have prefrontal dysfunction might reinforce the concept of presenteeism.

Mechanisms of gastrointestinal barrier dysfunction in COVID-19 patients

Coronavirus disease 2019(COVID-19)caused by the novel severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has become a major global public health event,resulting in a significant social and economic burden.Although COVID-19 was initially characterized as an upper respiratory and pulmonary infection,recent evidence suggests that it is a complex disease including gastrointestinal symptoms,such as diarrhea,nausea,and vomiting.Moreover,it remains unclear whether the gastrointestinal symptoms are caused by direct infection of the gastrointestinal tract by SARS-CoV-2 or are the result of systemic immune activation and subsequent dysregulation of homeostatic mechanisms.This review provides a brief overview of the mechanisms by which SARS-CoV-2 disrupts the integrity of the gastrointestinal barrier including the mechanical barrier,chemical barrier,microbial barrier,and immune barrier.

IgA nephropathy associated with Crohn's disease

The relationship between IgA nephropathy(IgAN)and Crohn’s disease was reported.IgAN is the most common primary glomerulonephritis and one of the leading causes of chronic kidney disease and end-stage renal failure,and up to 50%of cases progressed to end-stage renal disease within 25 years after IgAN diagnosis.However,specific and effective therapeutic strategies are still lacking.In this review,we discuss the possibility of the mechanism involved in IgAN associated with Crohn’s disease based on the findings of basic and clinical studies.Although the etiology of IgAN associated with Crohn’s disease is not permanent and various factors are thought to be involved,the stabilization of the disease condition of Crohn’s disease is believed to help treat IgAN.

与配偶共同生活的老年人参与社区活动意义的质性研究

目的目前,日本有65.3%的老年人是与伴侣共同生活,如果其中一方老人去世,另一方可能无法重建自己的生活方式,并可能出现健康问题或变得孤独。参与社区活动有助于他们保持身体、精神和社会健康。本研究旨在阐明夫妇家庭中老年人参与社区活动的意义。方法采用半结构式个人访谈收集资料。2019年2月在日本宫崎市选取6名65岁及以上的老年人,他们与配偶同住至少1年,并持续参加社区活动。采用KJ分析法(此方法由Kawakita Jiro开发,以自下而上的方式组织观点)对访谈资料进行内容分析,并由专业导师进行指导。结果共提炼出7个主题:1)与配偶建立合作关系:尊重其努力工作的意愿;2)考虑与其他组织的关系:关注每个细节;3)积极主动的态度:不要把所有事情都交给别人;4)质疑自己存在方式的态度:我自己与他人的联系;5)参与者之间的联系:提高对他人的认识;6)精神上的满足:外出活动的时间、地点和机会;7)持续参与社区活动的身心自控能力:提高保健意识。结论对于夫妻家庭中的老年人来说,参加社区活动有助于他们获得配偶的支持,并采取积极的态度,参与者之间的沟通有助于身心调节,且能改善他们的健康状况。

Effect of surface retaining elements on rock stability:laboratory investigation with sand powder 3D printing

This study aims to investigate the benefcial efects of surface retaining elements (SREs) on the mechanical behaviors of bolted rock and roadway stability. 3D printing (3DP) technology is utilized to create rock analogue prismatic specimens for conducting this investigation. Uniaxial compression tests with acoustic emission (AE) and digital image correlation techniques have been conducted on 3DP specimens bolted with diferent SREs. The results demonstrate that the strength and modulus of elasticity of the bolted specimens show a positive correlation with the area of the SRE;the AE characteristics of the bolted specimens are higher than those of the unbolted specimen, but they decrease with an increase in SRE area, thus further improving the integrity of the bolted specimens. The reinforcement efect of SREs on the surrounding rock of roadways is further analyzed using numerical modelling and feld test. The results provide a better understanding of the role of SREs in rock bolting and the optimization of rock bolting design. Furthermore, they verify the feasibility of 3DP for rock analogues in rock mechanics tests.

Deformation behaviour of magnesium bicrystals with symmetrical 90°<1120>tilt grain boundaries analysed by large area EBSD mapping

Grain boundaries play a significant role in the deformation of polycrystals.Their response to deformation is however not completely understood,particularly with respect to how they accommodate lattice rotation of adjoining crystallites by changing their structure and geometry.The current study thus investigates the deformation behaviour of Mg bicrystals with 90°<1120>symmetric tilt boundary strained in plane-strain compression up to different final strains.Due to the initial soft orientation of the two crystals,activation of basal slip in each crystal gave rise to lattice rotation around the transverse direction towards the compression direction of the channel-die.Hundreds of single EBSD maps with a small step size were obtained from the GB region and stitched together to produce large panoramic maps of a macroscopic scale.Although very time-consuming,this technique has proven useful in clarifying the origin of the non-uniform deformation zones in the vicinity of the grain boundary and explains the mechanisms,by which the grain boundary was able to cope with the imposed strain before fracture.Interestingly,several variants of extension twins were observed as an additional deformation mechanism despite having negative Schmid factors.Systematic investigation of their resulting combined shear components with respect to the sample coordinate system revealed an alignment along the longitudinal direction of the channel-die,therefore justifying their nucleation.

A promoting nitric oxide-releasing coating containing copper ion on ZE21B alloy for potential vascular stent application

Magnesium-based biodegradable metals as cardiovascular stents have shown a lot of excellent performance, which have been used to treat coronary artery diseases. However, the excessive degradation rate, imperfect biocompatibility and delayed re-endothelialization still lead to a considerable challenge for its application. In this work, to overcome these shortcomings, a compound of catalyzing nitric oxide(NO) generation containing copper ions(Cu^(2+)) and hyaluronic acid(HA), an important component of the extracellular matrix, were covalently immobilized on a hydrofluoric acid(HF)-pretreated ZE21B alloy via amination layer for improving its corrosion resistance and endothelialization. Specifically,the Cu^(2+) chelated firmly with a cyclen 1,4,7,10-tetraazacyclododecane-N’, N’’, N’’’, N-tetraacetic acid(DOTA) could form a stability of hybrid coating, avoiding the explosion of Cu^(2+). The chelated Cu^(2+) enabled the catalytic generation of NO and promoted the adhesion and proliferation of endothelial cells(ECs) in vascular micro-environment. In this case, the synergistic effect of NO-generation and endothelial glycocalyx molecules of HA lead to efficient ECs promotion and smooth muscle cells(SMCs) inhibition. Meanwhile, the blood compatibility also had achieved a marked improvement. Moreover, the standard electrochemical measurements indicated that the functionalized ZE21B alloy had better anti-corrosion ability. In a conclusion, the dual-functional coating displays a great potential in the field of biodegradable magnesium-based implantable cardiovascular stents.

Influence analysis of complex crack geometric parameters on mechanical properties of soft rock

Soft rocks, such as coal, are afected by sedimentary efects, and the surrounding rock mass of underground coal mines is generally soft and rich in joints and cracks. A clear and deep understanding of the relationship between crack geometric parameters and rock mechanics properties in cracked rock is greatly important to the design of engineering rock mass struc‑tures. In this study, computed tomography (CT) scanning was used to extract the internal crack network of coal specimens. Based on the crack size and dominant crack number, the parameters of crack area, volume, length, width, and angle were statistically analyzed by diferent sampling thresholds. In addition, the Pearson correlation coefcients between the crack parameters and uniaxial compression rock mechanics properties (uniaxial compressive strength UCS, elasticity modulus E) were calculated to quantitatively analyze the impact of each parameter. Furthermore, a method based on Pearson coefcients was used to grade the correlation between crack geometric parameters and rock mechanical properties to determine threshold values. The results indicated that the UCS and E of the specimens changed with the varied internal crack structures of the specimens, the crack parameters of area, volume, length and width all showed negative correlations with UCS and E, and the dominant crack played an important role both in weakening strength and stifness. The crack parameters of the angle are all positively correlated with the UCS and E. More crack statistics can signifcantly improve the correlation between the parameters of the crack angle and the rock mechanics properties, and the statistics of the geometric parameters of at least 16 cracks or the area larger than 5 mm2 are suggested for the analysis of complex cracked rock masses or physical reproduction using 3D printing. The results are validated and further analyzed with triaxial tests. The fndings of this study have important reference value for future research regarding the accurate and efcient selection of a few cracks with a signifcant infuence on the rock mechanical properties of surrounding rock mass structures in coal engineering.

A Quantum Tanimoto Coefficient Fidelity for Entanglement Measurement

Fidelity plays an important role in quantum information processing,which provides a basic scale for comparing two quantum states.At present,one of the most commonly used fidelities is Uhlmann-Jozsa(U-J)fidelity.However,U-J fidelity needs to calculate the square root of the matrix,which is not trivial in the case of large or infinite density matrices.Moreover,U-J fidelity is a measure of overlap,which has limitations in some cases and cannot reflect the similarity between quantum states well.Therefore,a novel quantum fidelity measure called quantum Tanimoto coefficient(QTC)fidelity is proposed in this paper.Unlike other existing fidelities,QTC fidelity not only considers the overlap between quantum states,but also takes into account the separation between quantum states for the first time,which leads to a better performance of measure.Specifically,we discuss the properties of the proposed QTC fidelity.QTC fidelity is compared with some existing fidelities through specific examples,which reflects the effectiveness and advantages of QTC fidelity.In addition,based on the QTC fidelity,three discrimination coefficients d_(1)^(QTC),d_(2)^(QTC),and d_^(3)^(QTC)are defined to measure the difference between quantum states.It is proved that the discrimination coefficient d_(3)^(QTC)is a true metric.Finally,we apply the proposed QTC fidelity-based discrimination coefficients to measure the entanglement of quantum states to show their practicability.

Synthesis strategies of covalent organic frameworks: An overview from nonconventional heating methods and reaction media

Covalent organic frameworks(COFs), as an emerging class of porous crystalline materials constructed by covalent links between the building monomers, have gained tremendous attention. Over the past 15 years, COFs have made rapid progress and substantial development in the chemistry and materials fields. However, the synthesis of COFs has been dominated by solvothermal methods for a long time and it usually involves high temperature, high pressure and toxic organic solvents, which created many challenges for environmental considerations. Recently,the exploration of new approaches for facile fabrication of COFs has aroused extensive interest. Hence, in this review, we comprehensively describe the synthetic strategies of COFs from the aspects of nonconventional heating methods and reaction media. In addition, the advantages,limitations and properties of the preparation methods are compared. Finally, we outline the main challenges and development prospects of the synthesis of COFs in the future and propose some possible solutions.