Recently,there are hesitations in the application scope of the classical Cassie theory and Wenzel theory.In this paper,Molecular Dynamics(MD)simulations are used to study these two theories used in the nanoscale and f...Recently,there are hesitations in the application scope of the classical Cassie theory and Wenzel theory.In this paper,Molecular Dynamics(MD)simulations are used to study these two theories used in the nanoscale and find their limitations.The effect of parameters including solid fractions(or roughness factors),arrangement of pillars(with same solid fractions),pillar height,and droplet size on contact angles was investigated.It shows that the Cassie equation is suitable for droplets on uniform pillared surfaces including different solid fractions,arrangement of pillars and pillar height,when there is no meniscus of droplets.The Wenzel equation is also suitable for droplets on uniform pillared surfaces including different roughness factors,arrangement of pillars and pillar heights.Moreover,whether the droplet size has an influence on the contact angle depends on the pinned place of the contact line.In the Wenzel state,the contact line is pinned although increasing the droplet size,resulting in increasing the contact angle,while the contact angle decreases to the initial value again when the droplet size increases enough to allow the contact line moving to the next pillar.The results provide insights toward the wettability of droplets on surfaces in nanoscale.展开更多
In this paper we provide evidence that the Cassie-to-Wenzel transition, despite its detrimental effects on the wetting properties of superhydrophobic surfaces, can be exploited as an effective micro-fabrication strate...In this paper we provide evidence that the Cassie-to-Wenzel transition, despite its detrimental effects on the wetting properties of superhydrophobic surfaces, can be exploited as an effective micro-fabrication strategy to obtain highly ordered arrays of biological objects. To this purpose we fabricated a patterned surface wetted in the Cassie state, where we deposited a droplet containing genomic DNA. We observed that, when the droplet wets the surface in the Cassie state, an array of DNA filaments pinned on the top edges between pillars is formed. Conversely, when the Cassie-to-Wenzel transition occurs, DNA can be pinned at different height between pillars. These results open the way to the realization of tridimensional arrays of biological objects.展开更多
Purpose–This research aims to investigate how the adhesion performance of GFRP composite components,commonly used in railway vehicles,is affected when bonded to cataphoresis coated steel substrate surfaces.Design/met...Purpose–This research aims to investigate how the adhesion performance of GFRP composite components,commonly used in railway vehicles,is affected when bonded to cataphoresis coated steel substrate surfaces.Design/methodology/approach–In this context,the aim was to determine the optimal adhesion parameters for bonding GFRP samples with natural and primed surfaces to steel samples with cataphoresis coatings.Then,single-lap joint samples with different bond thicknesses of 1 mm,2 mm and 3 mm were prepared.Finally,tensile tests were performed on the samples.Findings–The results showed that GFRP specimens with natural surfaces,characterised by the highest surface roughness,exhibited the lowest bond strength.But,the highest bonding performance was achieved in specimens where primed GFRP was bonded to cataphoresis coated steel,especially with a bond thickness of 1 mm,and achieving a yield strength of 20 MPa.This situation explains the characteristic difference between surface roughness and chemical coating,which are two essential pre-treatments in adhesive bonding.While surface roughness provides mechanical interlocking,excessive roughness can hinder the adhesive’s wetting ability,causing it to remain suspended on the surface as described in the Cassie–Baxter theorem.In contrast,it has been observed that,despite low surface roughness,chemical coatings enhance the bonding between primer paint and adhesive molecules,and–as stated in the Wenzel theorem–improve the surface wettability.Originality/value–As a preliminary preparation in the adhesive method,primer paint is applied to steel surfaces and GFRP material surfaces in classical industrial applications.In this research,the application of the catapheresis process to the steel substrate instead of primer paint and the bonding of primer-painted GFRP materials to this surface make a unique contribution to the research.展开更多
锑(Sb)是有色金属矿山开采和加工中对环境造成严重威胁的重点污染物,与砷(As)的硫化物和氧化物共存.微生物对土壤中重金属的迁移转化及修复具有重要意义.目前,锑矿不同功能分区(采矿区和冶炼区)中重金属有效态对土壤微生物群落结构的生...锑(Sb)是有色金属矿山开采和加工中对环境造成严重威胁的重点污染物,与砷(As)的硫化物和氧化物共存.微生物对土壤中重金属的迁移转化及修复具有重要意义.目前,锑矿不同功能分区(采矿区和冶炼区)中重金属有效态对土壤微生物群落结构的生态效应仍知之甚少.为掌握不同功能分区中重金属污染特征及重金属有效态与土壤微生物群落之间的相互作用关系,采用Wenzel连续提取法和16S r DNA高通量测序技术测定了Sb和As的化学形态及微生物信息.结果表明,Wenzel连续提取后Sb和As的化学形态分布占比大小为:无定型铁铝氧化物结合态(F3)>晶质铁铝氧化物结合态(F4)>残渣态(F5)>专性吸附态(F2)>非专性吸附态(F1).潜在生态风险指数(RI)和地累积指数(Igeo)显示,Sb污染程度大小为:冶炼区>采矿区>对照区,冶炼区为严重污染,采矿区为中度至重度污染;As污染程度大小为:采矿区>冶炼区>对照区,采矿区和冶炼区均为中度至重度污染.16S r DNA高通量测序显示:Proteobacteria是采矿区与冶炼区中相对丰度最高的门,Kaistobacter、Pseudomonas、Sphingomonas和Lysobacter是采矿区与冶炼区中相对丰度最高的属;Geobacter和Luteolibacter在采矿区有较高的LDA得分,Thiobacillus在冶炼区具有较高的LDA得分.Spearman相关性、方差分解(VPA)和随机森林预测(RF)表明,Sb、As、有效态锑[Sb(Bio)]和有效态砷[As(Bio)]是影响锑矿不同功能分区中微生物群落结构的主要因子;冗余分析(RDA)显示,对属水平微生物群落结构的影响大小为:As(Bio)>Sb(Bio)>Sb>As,Sb及Sb(Bio)和Nitrospira呈现显著负相关关系,和Thiobacillus呈现显著正相关关系(P<0.05).通过深入研究重金属污染特征及重金属有效态对微生物群落结构的生态效应,可为锑矿区生态修复和生态环境管理提供参考.展开更多
基金This work was supported by the National Natural Science Foundation of China(51905315)Shandong Provincial Natural Science Foundation(ZR2019BEMO12)+3 种基金the Scientific Research Foundation of Shandong University of Science and Technology for Recruited Talents(2019RCJJ001)the Fundamental Research Funds for theCentral Universities(20CX02317A)the Opening Fund of National Engineering Laboratory of Offshore Gcophysical and Exploration Equipmentthe Project of Shandong Province Higher Educational Young Innovative Talent Introduction and Cultivation Team(Environment function material innovation team).
文摘Recently,there are hesitations in the application scope of the classical Cassie theory and Wenzel theory.In this paper,Molecular Dynamics(MD)simulations are used to study these two theories used in the nanoscale and find their limitations.The effect of parameters including solid fractions(or roughness factors),arrangement of pillars(with same solid fractions),pillar height,and droplet size on contact angles was investigated.It shows that the Cassie equation is suitable for droplets on uniform pillared surfaces including different solid fractions,arrangement of pillars and pillar height,when there is no meniscus of droplets.The Wenzel equation is also suitable for droplets on uniform pillared surfaces including different roughness factors,arrangement of pillars and pillar heights.Moreover,whether the droplet size has an influence on the contact angle depends on the pinned place of the contact line.In the Wenzel state,the contact line is pinned although increasing the droplet size,resulting in increasing the contact angle,while the contact angle decreases to the initial value again when the droplet size increases enough to allow the contact line moving to the next pillar.The results provide insights toward the wettability of droplets on surfaces in nanoscale.
文摘In this paper we provide evidence that the Cassie-to-Wenzel transition, despite its detrimental effects on the wetting properties of superhydrophobic surfaces, can be exploited as an effective micro-fabrication strategy to obtain highly ordered arrays of biological objects. To this purpose we fabricated a patterned surface wetted in the Cassie state, where we deposited a droplet containing genomic DNA. We observed that, when the droplet wets the surface in the Cassie state, an array of DNA filaments pinned on the top edges between pillars is formed. Conversely, when the Cassie-to-Wenzel transition occurs, DNA can be pinned at different height between pillars. These results open the way to the realization of tridimensional arrays of biological objects.
文摘Purpose–This research aims to investigate how the adhesion performance of GFRP composite components,commonly used in railway vehicles,is affected when bonded to cataphoresis coated steel substrate surfaces.Design/methodology/approach–In this context,the aim was to determine the optimal adhesion parameters for bonding GFRP samples with natural and primed surfaces to steel samples with cataphoresis coatings.Then,single-lap joint samples with different bond thicknesses of 1 mm,2 mm and 3 mm were prepared.Finally,tensile tests were performed on the samples.Findings–The results showed that GFRP specimens with natural surfaces,characterised by the highest surface roughness,exhibited the lowest bond strength.But,the highest bonding performance was achieved in specimens where primed GFRP was bonded to cataphoresis coated steel,especially with a bond thickness of 1 mm,and achieving a yield strength of 20 MPa.This situation explains the characteristic difference between surface roughness and chemical coating,which are two essential pre-treatments in adhesive bonding.While surface roughness provides mechanical interlocking,excessive roughness can hinder the adhesive’s wetting ability,causing it to remain suspended on the surface as described in the Cassie–Baxter theorem.In contrast,it has been observed that,despite low surface roughness,chemical coatings enhance the bonding between primer paint and adhesive molecules,and–as stated in the Wenzel theorem–improve the surface wettability.Originality/value–As a preliminary preparation in the adhesive method,primer paint is applied to steel surfaces and GFRP material surfaces in classical industrial applications.In this research,the application of the catapheresis process to the steel substrate instead of primer paint and the bonding of primer-painted GFRP materials to this surface make a unique contribution to the research.
文摘锑(Sb)是有色金属矿山开采和加工中对环境造成严重威胁的重点污染物,与砷(As)的硫化物和氧化物共存.微生物对土壤中重金属的迁移转化及修复具有重要意义.目前,锑矿不同功能分区(采矿区和冶炼区)中重金属有效态对土壤微生物群落结构的生态效应仍知之甚少.为掌握不同功能分区中重金属污染特征及重金属有效态与土壤微生物群落之间的相互作用关系,采用Wenzel连续提取法和16S r DNA高通量测序技术测定了Sb和As的化学形态及微生物信息.结果表明,Wenzel连续提取后Sb和As的化学形态分布占比大小为:无定型铁铝氧化物结合态(F3)>晶质铁铝氧化物结合态(F4)>残渣态(F5)>专性吸附态(F2)>非专性吸附态(F1).潜在生态风险指数(RI)和地累积指数(Igeo)显示,Sb污染程度大小为:冶炼区>采矿区>对照区,冶炼区为严重污染,采矿区为中度至重度污染;As污染程度大小为:采矿区>冶炼区>对照区,采矿区和冶炼区均为中度至重度污染.16S r DNA高通量测序显示:Proteobacteria是采矿区与冶炼区中相对丰度最高的门,Kaistobacter、Pseudomonas、Sphingomonas和Lysobacter是采矿区与冶炼区中相对丰度最高的属;Geobacter和Luteolibacter在采矿区有较高的LDA得分,Thiobacillus在冶炼区具有较高的LDA得分.Spearman相关性、方差分解(VPA)和随机森林预测(RF)表明,Sb、As、有效态锑[Sb(Bio)]和有效态砷[As(Bio)]是影响锑矿不同功能分区中微生物群落结构的主要因子;冗余分析(RDA)显示,对属水平微生物群落结构的影响大小为:As(Bio)>Sb(Bio)>Sb>As,Sb及Sb(Bio)和Nitrospira呈现显著负相关关系,和Thiobacillus呈现显著正相关关系(P<0.05).通过深入研究重金属污染特征及重金属有效态对微生物群落结构的生态效应,可为锑矿区生态修复和生态环境管理提供参考.
基金partially supported by NSFC(No.12171037)the Fundamental Research Funds for the Central Universities+5 种基金partially supported by NSFC(Nos.12171037,12271040)China Postdoctoral Science Foundation(No.2022M720261)partially supported by NSFC(Nos.11931007,11871282)Nankai Zhide Foundation and Tianjin Outstanding Talents FoundationChina Postdoctoral Science Foundation(No.BX20230018)National Key R&D Program of China(No.2020YFA0712800)。
