Processing of materials by ultrashort laser pulses has evolved significantly over the last decade and is starting to reveal its scientific,technological and industrial potential.In ultrafast laser manufacturing,optica...Processing of materials by ultrashort laser pulses has evolved significantly over the last decade and is starting to reveal its scientific,technological and industrial potential.In ultrafast laser manufacturing,optical energy of tightly focused femtosecond or picosecond laser pulses can be delivered to precisely defined positions in the bulk of materials via two-/multi-photon excitation on a timescale much faster than thermal energy exchange between photoexcited electrons and lattice ions.Control of photoionization and thermal processes with the highest precision,inducing local photomodification in sub-100-nm-sized regions has been achieved.State-of-the-art ultrashort laser processing techniques exploit high 0.1–1μm spatial resolution and almost unrestricted three-dimensional structuring capability.Adjustable pulse duration,spatiotemporal chirp,phase front tilt and polarization allow control of photomodification via uniquely wide parameter space.Mature opto-electrical/mechanical technologies have enabled laser processing speeds approaching meters-per-second,leading to a fast lab-to-fab transfer.The key aspects and latest achievements are reviewed with an emphasis on the fundamental relation between spatial resolution and total fabrication throughput.Emerging biomedical applications implementing micrometer feature precision over centimeter-scale scaffolds and photonic wire bonding in telecommunications are highlighted.展开更多
An overview of plant surface structures and their evolution is presented. It combines surface chemistry and architecture with their functions and refers to possible biomimetic applications. Within some 3.5 billion yea...An overview of plant surface structures and their evolution is presented. It combines surface chemistry and architecture with their functions and refers to possible biomimetic applications. Within some 3.5 billion years biological species evolved highly complex multifunctional surfaces for interacting with their environments: some 10 million living prototypes(i.e., estimated number of existing plants and animals) for engineers. The complexity of the hierarchical structures and their functionality in biological organisms surpasses all abiotic natural surfaces: even superhydrophobicity is restricted in nature to living organisms and was probably a key evolutionary step with the invasion of terrestrial habitats some 350–450 million years ago in plants and insects. Special attention should be paid to the fact that global environmental change implies a dramatic loss of species and with it the biological role models. Plants, the dominating group of organisms on our planet, are sessile organisms with large multifunctional surfaces and thus exhibit particular intriguing features.Superhydrophilicity and superhydrophobicity are focal points in this work. We estimate that superhydrophobic plant leaves(e.g., grasses) comprise in total an area of around 250 million km^2, which is about 50% of the total surface of our planet. A survey of structures and functions based on own examinations of almost 20,000 species is provided, for further references we refer to Barthlott et al.(Philos. Trans. R. Soc. A 374: 20160191, 1). A basic difference exists between aquatic nonvascular and land-living vascular plants; the latter exhibit a particular intriguing surface chemistry and architecture. The diversity of features is described in detail according to their hierarchical structural order. The first underlying and essential feature is the polymer cuticle superimposed by epicuticular wax and the curvature of single cells up to complex multicellular structures. A descriptive terminology for this diversity is provided. Simplified, the fun展开更多
本研究拟在传统社交焦虑障碍团体认知行为疗法的基础上构建新治疗模式——"团体实证认知行为疗法(Empirical Group Cognitive-Behavioral Therapy,EGCBT)",模式鼓励来访者以科学研究的方式深入调研治疗关系以外"第三方&q...本研究拟在传统社交焦虑障碍团体认知行为疗法的基础上构建新治疗模式——"团体实证认知行为疗法(Empirical Group Cognitive-Behavioral Therapy,EGCBT)",模式鼓励来访者以科学研究的方式深入调研治疗关系以外"第三方"他人对社交焦虑相关问题的观念,进行认知取证,同时强调来访者对自我"正面和负面评价恐惧"内容进行实证检验。"团体实证认知行为疗法"注重利用"第三方"视角的真实信息为社交焦虑个体认知合理化提供更客观的依据,在传统认知行为治疗的基础上丰富实证模块及增强治疗模块间的递进关系。展开更多
Sedimentation based processes are widely used in industry to separate particles from a liquid phase. Since the advent of the ＂Nanoworld＂ the demand for effective separation technologies has rapidly risen, calling fo...Sedimentation based processes are widely used in industry to separate particles from a liquid phase. Since the advent of the ＂Nanoworld＂ the demand for effective separation technologies has rapidly risen, calling for the development of new separation concepts, one of which lies in hybrid separation using the superposition of a magnetic field for magnetic particles. Possible product portfolio of such separation consists of pigment production, nanomagnetics production for electronics and bio separation, A promising step in that direction is magnetic field enhanced cake filtration, which has by now progressed from batch to continuous ooeration. In sedimentation processes in a mass force field the settling behaviour of particles strongly depends on physico-chemical properties, concentration and size distribution of the particles. By adjusting the pH, the interparticle forces, in particular the electrostatic repulsion, can be manipulated. For remanent magnetic particles such as magnetite, pre-treatment in a magnetic field could lead to a change of interparticle interactions. By magnetizing the particles apart from van der Waals attraction and electrostatic repulsion, an additional potential is induced, the magnetic attraction, which could easily dominate the other potentials and result in agglomeration in the primary minimum. By sedimentation analysis, a wide spectrum of parameters like pH, magnetic field strength and concentration have been investigated. The results show a strong increase of sedimentation velocity by magnetic flocculation of the raw suspension. This leads to a rise in throughput due to the acceleration of sedimentation kinetics by imparting a non-chemical interaction to the physico-chemical properties in the feed stream of the separation apparatus.展开更多
In this study,we demonstrate a technique termed underwater persistent bubble assisted femtosecond laser ablation in liquids(UPB-fs-LAL)that can greatly expand the boundaries of surface micro/nanostructuring through la...In this study,we demonstrate a technique termed underwater persistent bubble assisted femtosecond laser ablation in liquids(UPB-fs-LAL)that can greatly expand the boundaries of surface micro/nanostructuring through laser ablation because of its capability to create concentric circular macrostructures with millimeter-scale tails on silicon substrates.Long-tailed macrostructures are composed of layered fan-shaped(central angles of 45°–141°)hierarchical micro/nanostructures,which are produced by fan-shaped beams refracted at the mobile bubble interface(.50°light tilt,referred to as the vertical incident direction)during UPB-fs-LAL line-by-line scanning.Marangoni flow generated during UPB-fs-LAL induces bubble movements.Fast scanning(e.g.1mms−1)allows a long bubble movement(as long as 2mm),while slow scanning(e.g.0.1mms−1)prevents bubble movements.When persistent bubbles grow considerably(e.g.hundreds of microns in diameter)due to incubation effects,they become sticky and can cause both gas-phase and liquidphase laser ablation in the central and peripheral regions of the persistent bubbles.This generates low/high/ultrahigh spatial frequency laser-induced periodic surface structures(LSFLs/HSFLs/UHSFLs)with periods of 550–900,100–200,40–100 nm,which produce complex hierarchical surface structures.A period of 40 nm,less than 1/25th of the laser wavelength(1030 nm),is the finest laser-induced periodic surface structures(LIPSS)ever created on silicon.The NIR-MIR reflectance/transmittance of fan-shaped hierarchical structures obtained by UPB-fs-LAL at a small line interval(5μm versus 10μm)is extremely low,due to both their extremely high light trapping capacity and absorbance characteristics,which are results of the structures’additional layers and much finer HSFLs.In the absence of persistent bubbles,only grooves covered with HSFLs with periods larger than 100 nm are produced,illustrating the unique attenuation abilities of laser properties(e.g.repetition rate,energy,incident angle,etc)by persistent bub展开更多
基金support by a project‘ReSoft’(SEN-13/2015)from the Research Council of Lithuaniasupport by JSPS Kakenhi Grant No.15K04637+1 种基金support via ARC Discovery DP120102980Gintas Šlekys for the partnership project with Altechna Ltd on industrial fs-laser fabrication.
文摘Processing of materials by ultrashort laser pulses has evolved significantly over the last decade and is starting to reveal its scientific,technological and industrial potential.In ultrafast laser manufacturing,optical energy of tightly focused femtosecond or picosecond laser pulses can be delivered to precisely defined positions in the bulk of materials via two-/multi-photon excitation on a timescale much faster than thermal energy exchange between photoexcited electrons and lattice ions.Control of photoionization and thermal processes with the highest precision,inducing local photomodification in sub-100-nm-sized regions has been achieved.State-of-the-art ultrashort laser processing techniques exploit high 0.1–1μm spatial resolution and almost unrestricted three-dimensional structuring capability.Adjustable pulse duration,spatiotemporal chirp,phase front tilt and polarization allow control of photomodification via uniquely wide parameter space.Mature opto-electrical/mechanical technologies have enabled laser processing speeds approaching meters-per-second,leading to a fast lab-to-fab transfer.The key aspects and latest achievements are reviewed with an emphasis on the fundamental relation between spatial resolution and total fabrication throughput.Emerging biomedical applications implementing micrometer feature precision over centimeter-scale scaffolds and photonic wire bonding in telecommunications are highlighted.
基金supported by the Deutsche Bundesstiftung Umwelt DBUthe German Research Council DFG+1 种基金the Federal Ministry for Science and Education BMBFthe Academy of Science and Literature in Mainz
文摘An overview of plant surface structures and their evolution is presented. It combines surface chemistry and architecture with their functions and refers to possible biomimetic applications. Within some 3.5 billion years biological species evolved highly complex multifunctional surfaces for interacting with their environments: some 10 million living prototypes(i.e., estimated number of existing plants and animals) for engineers. The complexity of the hierarchical structures and their functionality in biological organisms surpasses all abiotic natural surfaces: even superhydrophobicity is restricted in nature to living organisms and was probably a key evolutionary step with the invasion of terrestrial habitats some 350–450 million years ago in plants and insects. Special attention should be paid to the fact that global environmental change implies a dramatic loss of species and with it the biological role models. Plants, the dominating group of organisms on our planet, are sessile organisms with large multifunctional surfaces and thus exhibit particular intriguing features.Superhydrophilicity and superhydrophobicity are focal points in this work. We estimate that superhydrophobic plant leaves(e.g., grasses) comprise in total an area of around 250 million km^2, which is about 50% of the total surface of our planet. A survey of structures and functions based on own examinations of almost 20,000 species is provided, for further references we refer to Barthlott et al.(Philos. Trans. R. Soc. A 374: 20160191, 1). A basic difference exists between aquatic nonvascular and land-living vascular plants; the latter exhibit a particular intriguing surface chemistry and architecture. The diversity of features is described in detail according to their hierarchical structural order. The first underlying and essential feature is the polymer cuticle superimposed by epicuticular wax and the curvature of single cells up to complex multicellular structures. A descriptive terminology for this diversity is provided. Simplified, the fun
文摘本研究拟在传统社交焦虑障碍团体认知行为疗法的基础上构建新治疗模式——"团体实证认知行为疗法(Empirical Group Cognitive-Behavioral Therapy,EGCBT)",模式鼓励来访者以科学研究的方式深入调研治疗关系以外"第三方"他人对社交焦虑相关问题的观念,进行认知取证,同时强调来访者对自我"正面和负面评价恐惧"内容进行实证检验。"团体实证认知行为疗法"注重利用"第三方"视角的真实信息为社交焦虑个体认知合理化提供更客观的依据,在传统认知行为治疗的基础上丰富实证模块及增强治疗模块间的递进关系。
文摘Sedimentation based processes are widely used in industry to separate particles from a liquid phase. Since the advent of the ＂Nanoworld＂ the demand for effective separation technologies has rapidly risen, calling for the development of new separation concepts, one of which lies in hybrid separation using the superposition of a magnetic field for magnetic particles. Possible product portfolio of such separation consists of pigment production, nanomagnetics production for electronics and bio separation, A promising step in that direction is magnetic field enhanced cake filtration, which has by now progressed from batch to continuous ooeration. In sedimentation processes in a mass force field the settling behaviour of particles strongly depends on physico-chemical properties, concentration and size distribution of the particles. By adjusting the pH, the interparticle forces, in particular the electrostatic repulsion, can be manipulated. For remanent magnetic particles such as magnetite, pre-treatment in a magnetic field could lead to a change of interparticle interactions. By magnetizing the particles apart from van der Waals attraction and electrostatic repulsion, an additional potential is induced, the magnetic attraction, which could easily dominate the other potentials and result in agglomeration in the primary minimum. By sedimentation analysis, a wide spectrum of parameters like pH, magnetic field strength and concentration have been investigated. The results show a strong increase of sedimentation velocity by magnetic flocculation of the raw suspension. This leads to a rise in throughput due to the acceleration of sedimentation kinetics by imparting a non-chemical interaction to the physico-chemical properties in the feed stream of the separation apparatus.
文摘In this study,we demonstrate a technique termed underwater persistent bubble assisted femtosecond laser ablation in liquids(UPB-fs-LAL)that can greatly expand the boundaries of surface micro/nanostructuring through laser ablation because of its capability to create concentric circular macrostructures with millimeter-scale tails on silicon substrates.Long-tailed macrostructures are composed of layered fan-shaped(central angles of 45°–141°)hierarchical micro/nanostructures,which are produced by fan-shaped beams refracted at the mobile bubble interface(.50°light tilt,referred to as the vertical incident direction)during UPB-fs-LAL line-by-line scanning.Marangoni flow generated during UPB-fs-LAL induces bubble movements.Fast scanning(e.g.1mms−1)allows a long bubble movement(as long as 2mm),while slow scanning(e.g.0.1mms−1)prevents bubble movements.When persistent bubbles grow considerably(e.g.hundreds of microns in diameter)due to incubation effects,they become sticky and can cause both gas-phase and liquidphase laser ablation in the central and peripheral regions of the persistent bubbles.This generates low/high/ultrahigh spatial frequency laser-induced periodic surface structures(LSFLs/HSFLs/UHSFLs)with periods of 550–900,100–200,40–100 nm,which produce complex hierarchical surface structures.A period of 40 nm,less than 1/25th of the laser wavelength(1030 nm),is the finest laser-induced periodic surface structures(LIPSS)ever created on silicon.The NIR-MIR reflectance/transmittance of fan-shaped hierarchical structures obtained by UPB-fs-LAL at a small line interval(5μm versus 10μm)is extremely low,due to both their extremely high light trapping capacity and absorbance characteristics,which are results of the structures’additional layers and much finer HSFLs.In the absence of persistent bubbles,only grooves covered with HSFLs with periods larger than 100 nm are produced,illustrating the unique attenuation abilities of laser properties(e.g.repetition rate,energy,incident angle,etc)by persistent bub
