An investigation of ultrashort pulsed laser induced surface modification due to conditions that result in a superheated melted liquid layer and material evaporation are considered. To describe the surface modification occurring after cooling and resolidification of the melted layer and understand the underlying physical fundamental mechanisms, a unified model is presented to account for crater and subwavelength ripple formation based on a synergy of electron excitation and capillary waves solidification. The proposed theoretical framework aims to address the laser-material interaction in subablation conditions and thus minimal mass removal in combination with a hydrodynamics-based scenario of the crater creation and ripple formation following surface irradiation with single and multiple pulses, respectively. The development of the periodic structures is attributed to the interference of the incident wave with a surface plasmon wave. Details of the surface morphology attained are elaborated as a function of the imposed conditions and results are tested against experimental data.

Materials irradiated with multiple femtosecond laser pulses in sub-ablation conditions are observed to develop various types of self-assembled morphologies that range from nanoripples to periodic micro-grooves and quasi-periodic micro-spikes. Here, we present a physical scenario that couples electrodynamics, describing surface plasmon excitation, with hydrodynamics, describing Marangoni convection and counter-rolls, to elucidate this important sub-ablation regime of light matter interaction in which matter is being modified, however, the underlying process is not yet fully understood. The proposed physical mechanism could be generally applicable to practically any conductive material structured by ultrashort laser pulses, therefore it can be useful for the interpretation of further critical aspects of light matter interaction.

The exciting properties of micro-and nano-patterned surfaces found in natural species hide a virtually endless potential of technological ideas, opening new opportunities for innovation and exploitation in materials science and engineering. Due to the diversity of biomimetic surface functionalities, inspirations from natural surfaces are interesting for a broad range of applications in engineering, including phenomena of adhesion, friction, wear, lubrication, wetting phenomena, self-cleaning, antifouling, antibacterial phenomena, thermoregulation and optics. Lasers are increasingly proving to be promising tools for the precise and controlled structuring of materials at micro-and nano-scales. When ultrashort-pulsed lasers are used, the optimal interplay between laser and material parameters enables structuring down to the nanometer scale. Besides this, a unique aspect of laser processing technology is the possibility for material modifications at multiple (hierarchical) length scales, leading to the complex biomimetic micro-and nano-scale patterns, while adding a new dimension to structure optimization. This article reviews the current state of the art of laser processing methodologies, which are being used for the fabrication of bioinspired artificial surfaces to realize extraordinary wetting, optical, mechanical, and biological-active properties for numerous applications. The innovative aspect of laser functionalized biomimetic surfaces for a wide variety of current and future applications is particularly demonstrated and discussed. The article concludes with illustrating the wealth of arising possibilities and the number of new laser micro/nano fabrication approaches for obtaining complex high-resolution features, which prescribe a future where control of structures and subsequent functionalities are beyond our current imagination.

The significance of the magnitude of Prandtl number of a fluid in the propagation direction of induced convection rolls is elucidated. Specifically, we report on the physical mechanism to account for the formation and orientation of previously unexplored supra-wavelength periodic surface structures in dielectrics, following melting and subsequent capillary effects induced upon irradiation with ultrashort laser pulses. Counterintuitively, it is found that such structures exhibit periodicities, which are markedly, even multiple times, higher than the laser excitation wavelength. It turns out that the extent to which the hydrothermal waves relax depends upon the laser beam energy, produced electron densities upon excitation with femtosecond pulsed lasers, magnitude of the induced initial local roll disturbances and the magnitude of the Prandtl number with direct consequences on the orientation and size of the induced structures. It is envisaged that this elucidation may be useful for the interpretation of similar, albeit large-scale periodic or quasi-periodic structures formed in other natural systems due to thermal gradients, while it can also be of great importance for potential applications in biomimetics. PACS: 78.20.Bh 64.70.D-42.65.Re 77.90.+k The predominant role of convective flow in nonequilibrium spatial pattern formation has been demonstrated in various phenomena in nature such as on Earth's land and sea, as well as on planet's surface when large thermal or wind speed gradients are developed [1-4]. Similar fluid instabilities are also encountered in many industrial applications: heat exchangers [5] , evaporative cooling devices, and chemical vapor process [6], film flow in inclined porous substrates used in oil pipes [7], manufacturing of high purity semiconductor crystals [8].Similar patterns and more specifically, periodical structure formation are also induced on the surface or volume of many solids upon irradiation with laser beams [9][10][11]. This modification usually requires a solid to liquid phase transition followed by fluid movement and capillary effects. Whether classical Navier-Stokes equations and how a Newtonian fluid mechanics could determine quantitatively the characteristics of the molten material dynamics, still remain an open question.The formation of surface and bulk periodic structures gives rise to unique material properties and it has received considerable attention over the past decades due to a wide scope of applications regarding micro/nano-structuring of materials [12]. In this context, one timely area of exploration has been the ultrashort pulsed laser induced periodic structuring of dielectrics, due to its applicability in telecommunications, biomedicine and biomimetics [13][14][15][16][17]. The predominant physical mechanism to explain the formation of laser induced periodic surface structures (LIPSS) suggests that excited electron densities modify the dielectric constant and the refractive index n [18] leading to low spatial frequency LIPSS (LSFL). Alternative mechanisms to...

Microtubule (MT) plus end–tracking proteins (+TIPs) specifically recognize the ends of growing MTs. +TIPs are involved in diverse cellular processes such as cell division, cell migration, and cell polarity. Although +TIP tracking is important for these processes, the mechanisms underlying plus end specificity of mammalian +TIPs are not completely understood. Cytoplasmic linker protein 170 (CLIP-170), the prototype +TIP, was proposed to bind to MT ends with high affinity, possibly by copolymerization with tubulin, and to dissociate seconds later. However, using fluorescence-based approaches, we show that two +TIPs, CLIP-170 and end-binding protein 3 (EB3), turn over rapidly on MT ends. Diffusion of CLIP-170 and EB3 appears to be rate limiting for their binding to MT plus ends. We also report that the ends of growing MTs contain a surplus of sites to which CLIP-170 binds with relatively low affinity. We propose that the observed loss of fluorescent +TIPs at plus ends does not reflect the behavior of single molecules but is a result of overall structural changes of the MT end.