Elif Kacar | Kocaeli University (original) (raw)

Papers by Elif Kacar

International Journal of Engineering and Geosciences, May 8, 2023

Accurate and timely availability of LiDAR data is vital in some cases. To facilitate monitoring o... more Accurate and timely availability of LiDAR data is vital in some cases. To facilitate monitoring of any environmental changes, LiDAR systems can be designed, and carried by UAV platforms that can take off without major preparation. In this study, the methodology of the real-time LiDAR mapping system was developed in the laboratory. The designed system shortens the target-based flight planning and post-flight data processing. In this system, the data is taken instantly and thus the change in the mapping area can be detected quickly. The simulation system, produce 3D point cloud, and data was stored in a database for later analysis. The 3D visualization of the data obtained from our developed UAV-LiDAR system was carried out with a platform-independent interface designed as webbased. The X3D file format used in the study to produce 3D point data provide an infrastructure for AI and ML-based systems in identifying urban objects in systems containing big data such as LiDAR.

International Journal of Engineering and Geosciences

Accurate and timely availability of LiDAR data is vital in some cases. To facilitate monitoring o... more Accurate and timely availability of LiDAR data is vital in some cases. To facilitate monitoring of any environmental changes, LiDAR systems can be designed, carried by UAV platforms that can take off without major preparation. This study, a real-time mapping system was designed that shortens the processes of target-based flight planning and post-flight data processing. With this developed real-time LiDAR mapping system in laboratory, data is obtained instantly, so that the change in the area in question can be detected and fast solutions can be produced to the problems. In our simulation system, we have developed, besides the production of an instant 3D point cloud, this data is also instantly stored in a database for later analysis. The X3D scene we use in our study to produce 3D point data provide an infrastructure for AI and ML-based systems in identifying urban objects in systems containing big data such as LiDAR.

International Symposium on Applied Geoinformatics 2021, 2022

Accurate and timely availability of LiDAR data is vital in some cases. To make maps and facilitat... more Accurate and timely availability of LiDAR data is vital in some cases. To make maps and facilitate monitoring of any environmental changes, LiDAR systems can be designed, carried by UAV platforms that can take off without major preparation. In this study, a real-time mapping system was designed that shortens the processes of target-based flight planning, regular trajectory determination and post-flight data processing. With this developed real-time LiDAR mapping system in laboratory, data is obtained instantaneously, so that the change of the area in question can be followed and quick solutions can be produced for the detected problems.

2021 International Conference on INnovations in Intelligent SysTems and Applications (INISTA)

RSC Advances

Digital image processing of Cu layer on MWCNT/PP nanocomposite substrate after laser direct struc... more Digital image processing of Cu layer on MWCNT/PP nanocomposite substrate after laser direct structuring and autocatalytic plating reveals percolation effect.

Scientific Reports, 2016

In this work a novel colour-difference measurement method for the quality evaluation of copper de... more In this work a novel colour-difference measurement method for the quality evaluation of copper deposited on a polymer is proposed. Laser-induced selective activation (LISA) was performed onto the surface of the polycarbonate/acrylonitrile butadiene styrene (PC/ABS) polymer by using nanosecond laser irradiation. The laser activated PC/ABS polymer was copper plated by using the electroless copper plating (ECP) procedure. The sheet resistance measured by using a four-point probe technique was found to decrease by the power law with the colour-difference of the sample images after LISA and ECP procedures. The percolation theory of the electrical conductivity of the insulator conductor mixture has been adopted in order to explain the experimental results. The new proposed method was used to determine an optimal set of the laser processing parameters for best plating conditions. Polymer-based electrical devices are used in different areas such as optical communications, biomedicine, and automotive industry 1,2. Formation of the electrical circuits on polymers is important for these devices. There are many techniques called "selective metallization" to produce a circuit on the surface of polymers: direct chemical plating 3 , laser direct structuring (ablation and writing) 4,5 , laser direct imaging 6 and laser-induced selective activation (LISA) 7-11. LISA was developed for selective metallization of polymers for three-dimensional moulded interconnecting devices. This method contains single step: laser structuring of the polymer surface. As a result of the laser structuring, sponge-like and nano-porous structures are created to improve the adhesion strength of the metal to the polymer. After LISA process the metal layer is deposited by the electroless copper plating (ECP) procedure. The ECP contains of three-steps: activation of the laser-structured surface with palladium colloidal activator; cleaning with distilled water; electroless deposition of copper layer on the activated sample. In the activation procedure, palladium atoms are trapped in a porous sponge like structures on the polymer surface. Cleaning with distilled water removes unwanted palladium from flat unstructured polymer and leaves it confined in the poriferous surface. The copper fills all the openings in the polymer and a porous, rough metal film is deposited during the final step of the ECP. Finally, after both, LISA and ECP procedures, the copper layer is deposited selectively only onto the laser structured areas while unstructured polymer is not coated with the metal deposition. The electrical and optical properties of the semi-transparent films were investigated in numerous works 12-19. However, the analysis of the sheet resistance dependence on the optical transmittance can be applied only for films with the thicknesses smaller than the absorption depth. Such kind of measurements cannot be realized with a relatively thick metal layer on the porous opaque substrate. The characterization of the cross section of the metal plated polymer by the LISA and ECP procedures has been performed in the previous work by Y. Zhang et al. 7. The bearing ratio versus depth of the porous surface

Journal of Inorganic and Organometallic Polymers and Materials, 2016

Extreme ultraviolet lithography (EUVL) requires an emission of soft x-rays around a wavelength re... more Extreme ultraviolet lithography (EUVL) requires an emission of soft x-rays around a wavelength region of 13.5 nm. EHYBRID simulation was made under the laser operation at 1064 nm with a pulse duration of 6 ns. Intensity was changed between 1 x 10 12 W/cm2 and 5 x 10 12 W/cm2. Soft X-rays emitted from Sn XII and Sn XIII ions

Spectroscopy Letters, 2007

Optics & Laser Technology, 2013

In this study laser induced breakdown spectroscopy (LIBS) is applied for depth profile analysis o... more In this study laser induced breakdown spectroscopy (LIBS) is applied for depth profile analysis of galvanized steel sheet widely used in automobile industry. The effects of laser processing parameters, such as laser energy, laser spot size, and coating thickness were investigated to find out depth resolution by applying Taguchi optimization method. According to confirmation experiments of using optimum parameters, it is found out that experimental results are compatible with Taguchi Method with a 83% rate. Numerical simulation of the heat transfer equation is also performed for single laser pulse irradiation since the physical phenomena involved in the laser induced process can be more accurately studied by investigating the effect of single pulse irradiation on the target surface.

Optics & Laser Technology, 2013

This paper reports the production of gold nanoparticles (NPs) with controlled morphology in an aq... more This paper reports the production of gold nanoparticles (NPs) with controlled morphology in an aqueous solution of sodium dodecyl sulfate (SDS) by Ti:Sapphire laser. When nanostructures were exposed to an additional laser irradiation/exposure at a particular wavelength corresponding to resonant excitation of surface plasmons or to an interband transition, a considerable size reduction of NPs from 78 nm to 15 nm has been achieved. This can simply be defined as size refining of NPs by a two-step laser ablation. The relationship between supercontinuum (SC) emission and absorption spectrum of gold NPs has been explored. Additionally the transformation of gold NPs into fractal-like structures has been examined. At longer exposure periods, it is observed that there is a tendency of assembling of NPs into one-dimensional (1d) nanostructures.

Optics & Laser Technology, 2013

This paper reports an experimental study of welding of dissimilar materials between transparent P... more This paper reports an experimental study of welding of dissimilar materials between transparent Polymethylmethacrylate (PMMA) and stainless steel 304 sheets using a pulsed mode Nd:YAG laser. The process was carried out for two cases; laser transmission joining (LTJ) and conduction joining (CJ). The former is achieved when the joint is irradiated from the polymer side and the latter when the joint is irradiated from the opposite side (metal side). The light and process parameters represented by the peak power (P p ), pulse duration (t), pulse repetition rate (PRR), scanning speed (n) and pulse shape have a significant effect on the joint strength (F b ), joint bead width (b), joint quality and appearance. The optimum parameters were determined according to joint quality, joint strength and bead width. The optimum results for the joint strength and bead width for both LTJ and CJ are 925 N, 7.25 mm and 495 N, 8 mm respectively using a rectangular pulse shape (RC). Further modeling studies were carried out based on two methods; one factor at a time method (OFM) and surface response methodology (RSM) method. RSM was used to determine optimum parameters for the experimental data building mathematical models for correlating parameters and responses (F b and b) as well as to investigate how different parameters interact with each other and their effect on the weld quality.

Optics & Laser Technology, 2013

Since last decade, Pulsed Laser Ablation in Liquid (PLAL) has become an increasingly important te... more Since last decade, Pulsed Laser Ablation in Liquid (PLAL) has become an increasingly important technique for the production of the nanoparticles (NPs) since it usually provides high purity nanoparticle systems. This paper reports on the production and fragmentation of titanium oxide TiO 2 nanoparticles by pulsed laser ablation of a titanium target immersed in Sodium Dodecyl Sulfate (SDS) solution using an ultrafast Ti:Sapphire laser. After the production of TiO 2 nanoparticles for 30 min of laser irradiation, second harmonics of the laser wavelength are re-applied for different energies (180,120, 60 mJ) to SDS solution containing TiO 2 colloids in order to fragment relatively large pieces to obtain smaller ones. It was found that size of nanoparticles after the treatment is independent of the initial characteristics of colloids, but depends strongly on laser parameters especially pulse energy and on the presence of chemically active species in the solution. It was reported that particle size and size distribution range can be decreased using second harmonics of Ti:Sapphire laser wavelengths by using different values of energy. Re-irradiation process at average energy value of 180 μJ decreased average particle size from 185 nm to 110 nm. Characterization of the NPs was studied by applying various techniques such as UV-visible (UV-vis.), Transmission Electron Microscope (TEM), Dynamic Light Scattering (DLS) and Fourier Transform Infra-Red (FTIR).

Materials Science and Engineering: C, 2013

In-stent restenosis is a common complication after stent surgery which leads to a dangerous wall ... more In-stent restenosis is a common complication after stent surgery which leads to a dangerous wall narrowing of a blood vessel. Laser assisted patterning is one of the effective methods to modify the stent surface to control cell-surface interactions which play a major role in the restenosis. In this current study, 316LS stainless steel substrates are structured by focusing a femtosecond laser beam down to a spot size of 50 μm. By altering the laser induced spot density three distinct surfaces (low density (LD), medium density (MD) and high density (HD)) were prepared. While such surfaces are composed of primary microstructures, due to fast melting and re-solidification by ultra-short laser pulses, nanofeatures are also observed as secondary structures. Following a detailed surface characterization (chemical and physical properties of the surface), we used a well-established co-culture assay of human microvascular endothelial cells and human fibroblasts to check the cell compatibility of the prepared surfaces. The surfaces were analyzed in terms of cell adherence, proliferation, cell morphology and the differentiation of the fibroblast into the myofibroblast, which is a process indicating a general fibrotic shift within a certain tissue. It is observed that myofibroblast proliferation decreases significantly on laser treated samples in comparison to non-treated ones. On the other hand endothelial cell proliferation is not affected by the surface topography which is composed of micro-and nanostructures. Such surfaces may be used to modify stent surfaces for prevention or at least reduction of restenosis.

Journal of Materials Processing Technology, 2009

Laser micromachining can replace mechanical removal methods in many industrial applications, part... more Laser micromachining can replace mechanical removal methods in many industrial applications, particularly in the processing of difficult-to-machine materials such as hardened metals, ceramics, and composites. It is being applied across many industries like semiconductor, electronics, medical, automotive, aerospace, instrumentation and communications. Laser machining is a thermal process. The effectiveness of this process depends on thermal and optical properties of the material. Therefore, laser machining is suitable for materials that exhibit a high degree of brittleness, or hardness, and have favourable thermal properties, such as low thermal diffusivity and conductivity. Ceramics which have the mentioned properties are used extensively in the microelectronics industry for scribing and hole drilling.

Colloids and Surfaces B: Biointerfaces, 2013

Cell-material surface interaction plays a critical role in osseointegration of prosthetic implant... more Cell-material surface interaction plays a critical role in osseointegration of prosthetic implants used in orthopedic surgeries and dentistry. Different technical approaches exist to improve surface properties of such implants either by coating or by modification of their topography. Femtosecond laser treatment was used in this study to generate microspotted lines separated by 75, 125, or 175 m wide nanostructured interlines on stainless steel (316L) plates. The hydrophobicity and carbon content of the metallic surface were improved simultaneously through this method. In vitro testing of the laser treated plates revealed a significant improvement in adhesion of human endothelial cells and human bone marrow mesenchymal stem cells (hBM MSCs), the cells involved in microvessel and bone formation, respectively, and a significant decrease in fibroblast adhesion, which is implicated in osteolysis and aseptic loosening of prostheses. The hBM MSCs showed an increased bone formation rate on the laser treated plates under osteogenic conditions; the highest mineral deposition was obtained on the surface with 125 m interline distance (292 ± 18 mg/cm 2 vs. 228 ± 43 mg/cm 2 on untreated surface). Further in vivo testing of these laser treated surfaces in the native prosthetic implant niche would give a real insight into their effectiveness in improving osseointegration and their potential use in clinical applications.

International Journal of Engineering and Geosciences, May 8, 2023

Accurate and timely availability of LiDAR data is vital in some cases. To facilitate monitoring o... more Accurate and timely availability of LiDAR data is vital in some cases. To facilitate monitoring of any environmental changes, LiDAR systems can be designed, and carried by UAV platforms that can take off without major preparation. In this study, the methodology of the real-time LiDAR mapping system was developed in the laboratory. The designed system shortens the target-based flight planning and post-flight data processing. In this system, the data is taken instantly and thus the change in the mapping area can be detected quickly. The simulation system, produce 3D point cloud, and data was stored in a database for later analysis. The 3D visualization of the data obtained from our developed UAV-LiDAR system was carried out with a platform-independent interface designed as webbased. The X3D file format used in the study to produce 3D point data provide an infrastructure for AI and ML-based systems in identifying urban objects in systems containing big data such as LiDAR.

International Journal of Engineering and Geosciences

Accurate and timely availability of LiDAR data is vital in some cases. To facilitate monitoring o... more Accurate and timely availability of LiDAR data is vital in some cases. To facilitate monitoring of any environmental changes, LiDAR systems can be designed, carried by UAV platforms that can take off without major preparation. This study, a real-time mapping system was designed that shortens the processes of target-based flight planning and post-flight data processing. With this developed real-time LiDAR mapping system in laboratory, data is obtained instantly, so that the change in the area in question can be detected and fast solutions can be produced to the problems. In our simulation system, we have developed, besides the production of an instant 3D point cloud, this data is also instantly stored in a database for later analysis. The X3D scene we use in our study to produce 3D point data provide an infrastructure for AI and ML-based systems in identifying urban objects in systems containing big data such as LiDAR.

International Symposium on Applied Geoinformatics 2021, 2022

Accurate and timely availability of LiDAR data is vital in some cases. To make maps and facilitat... more Accurate and timely availability of LiDAR data is vital in some cases. To make maps and facilitate monitoring of any environmental changes, LiDAR systems can be designed, carried by UAV platforms that can take off without major preparation. In this study, a real-time mapping system was designed that shortens the processes of target-based flight planning, regular trajectory determination and post-flight data processing. With this developed real-time LiDAR mapping system in laboratory, data is obtained instantaneously, so that the change of the area in question can be followed and quick solutions can be produced for the detected problems.

2021 International Conference on INnovations in Intelligent SysTems and Applications (INISTA)

RSC Advances

Digital image processing of Cu layer on MWCNT/PP nanocomposite substrate after laser direct struc... more Digital image processing of Cu layer on MWCNT/PP nanocomposite substrate after laser direct structuring and autocatalytic plating reveals percolation effect.

Scientific Reports, 2016

In this work a novel colour-difference measurement method for the quality evaluation of copper de... more In this work a novel colour-difference measurement method for the quality evaluation of copper deposited on a polymer is proposed. Laser-induced selective activation (LISA) was performed onto the surface of the polycarbonate/acrylonitrile butadiene styrene (PC/ABS) polymer by using nanosecond laser irradiation. The laser activated PC/ABS polymer was copper plated by using the electroless copper plating (ECP) procedure. The sheet resistance measured by using a four-point probe technique was found to decrease by the power law with the colour-difference of the sample images after LISA and ECP procedures. The percolation theory of the electrical conductivity of the insulator conductor mixture has been adopted in order to explain the experimental results. The new proposed method was used to determine an optimal set of the laser processing parameters for best plating conditions. Polymer-based electrical devices are used in different areas such as optical communications, biomedicine, and automotive industry 1,2. Formation of the electrical circuits on polymers is important for these devices. There are many techniques called "selective metallization" to produce a circuit on the surface of polymers: direct chemical plating 3 , laser direct structuring (ablation and writing) 4,5 , laser direct imaging 6 and laser-induced selective activation (LISA) 7-11. LISA was developed for selective metallization of polymers for three-dimensional moulded interconnecting devices. This method contains single step: laser structuring of the polymer surface. As a result of the laser structuring, sponge-like and nano-porous structures are created to improve the adhesion strength of the metal to the polymer. After LISA process the metal layer is deposited by the electroless copper plating (ECP) procedure. The ECP contains of three-steps: activation of the laser-structured surface with palladium colloidal activator; cleaning with distilled water; electroless deposition of copper layer on the activated sample. In the activation procedure, palladium atoms are trapped in a porous sponge like structures on the polymer surface. Cleaning with distilled water removes unwanted palladium from flat unstructured polymer and leaves it confined in the poriferous surface. The copper fills all the openings in the polymer and a porous, rough metal film is deposited during the final step of the ECP. Finally, after both, LISA and ECP procedures, the copper layer is deposited selectively only onto the laser structured areas while unstructured polymer is not coated with the metal deposition. The electrical and optical properties of the semi-transparent films were investigated in numerous works 12-19. However, the analysis of the sheet resistance dependence on the optical transmittance can be applied only for films with the thicknesses smaller than the absorption depth. Such kind of measurements cannot be realized with a relatively thick metal layer on the porous opaque substrate. The characterization of the cross section of the metal plated polymer by the LISA and ECP procedures has been performed in the previous work by Y. Zhang et al. 7. The bearing ratio versus depth of the porous surface

Journal of Inorganic and Organometallic Polymers and Materials, 2016

Extreme ultraviolet lithography (EUVL) requires an emission of soft x-rays around a wavelength re... more Extreme ultraviolet lithography (EUVL) requires an emission of soft x-rays around a wavelength region of 13.5 nm. EHYBRID simulation was made under the laser operation at 1064 nm with a pulse duration of 6 ns. Intensity was changed between 1 x 10 12 W/cm2 and 5 x 10 12 W/cm2. Soft X-rays emitted from Sn XII and Sn XIII ions

Spectroscopy Letters, 2007

Optics & Laser Technology, 2013

In this study laser induced breakdown spectroscopy (LIBS) is applied for depth profile analysis o... more In this study laser induced breakdown spectroscopy (LIBS) is applied for depth profile analysis of galvanized steel sheet widely used in automobile industry. The effects of laser processing parameters, such as laser energy, laser spot size, and coating thickness were investigated to find out depth resolution by applying Taguchi optimization method. According to confirmation experiments of using optimum parameters, it is found out that experimental results are compatible with Taguchi Method with a 83% rate. Numerical simulation of the heat transfer equation is also performed for single laser pulse irradiation since the physical phenomena involved in the laser induced process can be more accurately studied by investigating the effect of single pulse irradiation on the target surface.

Optics & Laser Technology, 2013

This paper reports the production of gold nanoparticles (NPs) with controlled morphology in an aq... more This paper reports the production of gold nanoparticles (NPs) with controlled morphology in an aqueous solution of sodium dodecyl sulfate (SDS) by Ti:Sapphire laser. When nanostructures were exposed to an additional laser irradiation/exposure at a particular wavelength corresponding to resonant excitation of surface plasmons or to an interband transition, a considerable size reduction of NPs from 78 nm to 15 nm has been achieved. This can simply be defined as size refining of NPs by a two-step laser ablation. The relationship between supercontinuum (SC) emission and absorption spectrum of gold NPs has been explored. Additionally the transformation of gold NPs into fractal-like structures has been examined. At longer exposure periods, it is observed that there is a tendency of assembling of NPs into one-dimensional (1d) nanostructures.

Optics & Laser Technology, 2013

This paper reports an experimental study of welding of dissimilar materials between transparent P... more This paper reports an experimental study of welding of dissimilar materials between transparent Polymethylmethacrylate (PMMA) and stainless steel 304 sheets using a pulsed mode Nd:YAG laser. The process was carried out for two cases; laser transmission joining (LTJ) and conduction joining (CJ). The former is achieved when the joint is irradiated from the polymer side and the latter when the joint is irradiated from the opposite side (metal side). The light and process parameters represented by the peak power (P p ), pulse duration (t), pulse repetition rate (PRR), scanning speed (n) and pulse shape have a significant effect on the joint strength (F b ), joint bead width (b), joint quality and appearance. The optimum parameters were determined according to joint quality, joint strength and bead width. The optimum results for the joint strength and bead width for both LTJ and CJ are 925 N, 7.25 mm and 495 N, 8 mm respectively using a rectangular pulse shape (RC). Further modeling studies were carried out based on two methods; one factor at a time method (OFM) and surface response methodology (RSM) method. RSM was used to determine optimum parameters for the experimental data building mathematical models for correlating parameters and responses (F b and b) as well as to investigate how different parameters interact with each other and their effect on the weld quality.

Optics & Laser Technology, 2013

Since last decade, Pulsed Laser Ablation in Liquid (PLAL) has become an increasingly important te... more Since last decade, Pulsed Laser Ablation in Liquid (PLAL) has become an increasingly important technique for the production of the nanoparticles (NPs) since it usually provides high purity nanoparticle systems. This paper reports on the production and fragmentation of titanium oxide TiO 2 nanoparticles by pulsed laser ablation of a titanium target immersed in Sodium Dodecyl Sulfate (SDS) solution using an ultrafast Ti:Sapphire laser. After the production of TiO 2 nanoparticles for 30 min of laser irradiation, second harmonics of the laser wavelength are re-applied for different energies (180,120, 60 mJ) to SDS solution containing TiO 2 colloids in order to fragment relatively large pieces to obtain smaller ones. It was found that size of nanoparticles after the treatment is independent of the initial characteristics of colloids, but depends strongly on laser parameters especially pulse energy and on the presence of chemically active species in the solution. It was reported that particle size and size distribution range can be decreased using second harmonics of Ti:Sapphire laser wavelengths by using different values of energy. Re-irradiation process at average energy value of 180 μJ decreased average particle size from 185 nm to 110 nm. Characterization of the NPs was studied by applying various techniques such as UV-visible (UV-vis.), Transmission Electron Microscope (TEM), Dynamic Light Scattering (DLS) and Fourier Transform Infra-Red (FTIR).

Materials Science and Engineering: C, 2013

In-stent restenosis is a common complication after stent surgery which leads to a dangerous wall ... more In-stent restenosis is a common complication after stent surgery which leads to a dangerous wall narrowing of a blood vessel. Laser assisted patterning is one of the effective methods to modify the stent surface to control cell-surface interactions which play a major role in the restenosis. In this current study, 316LS stainless steel substrates are structured by focusing a femtosecond laser beam down to a spot size of 50 μm. By altering the laser induced spot density three distinct surfaces (low density (LD), medium density (MD) and high density (HD)) were prepared. While such surfaces are composed of primary microstructures, due to fast melting and re-solidification by ultra-short laser pulses, nanofeatures are also observed as secondary structures. Following a detailed surface characterization (chemical and physical properties of the surface), we used a well-established co-culture assay of human microvascular endothelial cells and human fibroblasts to check the cell compatibility of the prepared surfaces. The surfaces were analyzed in terms of cell adherence, proliferation, cell morphology and the differentiation of the fibroblast into the myofibroblast, which is a process indicating a general fibrotic shift within a certain tissue. It is observed that myofibroblast proliferation decreases significantly on laser treated samples in comparison to non-treated ones. On the other hand endothelial cell proliferation is not affected by the surface topography which is composed of micro-and nanostructures. Such surfaces may be used to modify stent surfaces for prevention or at least reduction of restenosis.

Journal of Materials Processing Technology, 2009

Laser micromachining can replace mechanical removal methods in many industrial applications, part... more Laser micromachining can replace mechanical removal methods in many industrial applications, particularly in the processing of difficult-to-machine materials such as hardened metals, ceramics, and composites. It is being applied across many industries like semiconductor, electronics, medical, automotive, aerospace, instrumentation and communications. Laser machining is a thermal process. The effectiveness of this process depends on thermal and optical properties of the material. Therefore, laser machining is suitable for materials that exhibit a high degree of brittleness, or hardness, and have favourable thermal properties, such as low thermal diffusivity and conductivity. Ceramics which have the mentioned properties are used extensively in the microelectronics industry for scribing and hole drilling.

Colloids and Surfaces B: Biointerfaces, 2013

Cell-material surface interaction plays a critical role in osseointegration of prosthetic implant... more Cell-material surface interaction plays a critical role in osseointegration of prosthetic implants used in orthopedic surgeries and dentistry. Different technical approaches exist to improve surface properties of such implants either by coating or by modification of their topography. Femtosecond laser treatment was used in this study to generate microspotted lines separated by 75, 125, or 175 m wide nanostructured interlines on stainless steel (316L) plates. The hydrophobicity and carbon content of the metallic surface were improved simultaneously through this method. In vitro testing of the laser treated plates revealed a significant improvement in adhesion of human endothelial cells and human bone marrow mesenchymal stem cells (hBM MSCs), the cells involved in microvessel and bone formation, respectively, and a significant decrease in fibroblast adhesion, which is implicated in osteolysis and aseptic loosening of prostheses. The hBM MSCs showed an increased bone formation rate on the laser treated plates under osteogenic conditions; the highest mineral deposition was obtained on the surface with 125 m interline distance (292 ± 18 mg/cm 2 vs. 228 ± 43 mg/cm 2 on untreated surface). Further in vivo testing of these laser treated surfaces in the native prosthetic implant niche would give a real insight into their effectiveness in improving osseointegration and their potential use in clinical applications.