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Despite decades of rapid development, the response times of electronic detectors are still orders of magnitude behind the time scales achieved and dealt with in Ultrafast Optics and Photonics. In these fields, researchers routinely experiment on physical phenomena spanning picosecond femtosecond and attosecond time windows. As a result, special non-trivial characterization methods are needed for dealing with such extremely short durations. This demand has brought about myriads of ideas and methods for Ultrashort Pulse Characterization. The oldest ancestor of these methods is "autocorrelation", which uses a short event to measure itself, yielding (usually but not always) good approximation of pulse duration. Despite its long history in use, autocorrelation has certain severe drawbacks. Fortunately, however, the field of ultrashort pulse characterization has gone much further beyond the limited estimates from simple autocorrelations. Today, we can extract the complete temporal / spectral evolution of ultrashort pulses, including both the intensity and phase information. Even further, space-time couplings and complete spatio– temporal electric fields can also be extracted with high sensitivity and reliability.

Sizing (ahar) has been used extensively in Turkish-Islamic handwritten documents. In this study, we present comparative experimental results including femtosecond (fs) and nanosecond (ns) pulsed laser cleaning of model paper samples with various types of sizing. The samples were artificially soiled with graphite and graphite-kaolinite mixture. For aging, the samples were exposed to air at 90 C temperature and 50% relative humidity during 16 days. Thickness variations of corn starch sizing were determined, and absorbance and transmittance values of corn, wheat and alum-egg sizing types at UV, VIS and IR wavelengths were measured for comparison. Two different methods and lasers were used for cleaning. In the first method, Yb:Glass fs laser beam (1030 nm wavelength) was focused on the paper surface by using a cylindrical lens (25 mm focal length). Square regions were cleaned through scanning the samples under laser light. Laser fluence was varied in the range of 0.39 - 0.78 J/cm(2). In the second method, a Q-switched Nd:YAG ns laser was operated at fundamental (1064 nm) and second harmonic (532 nm) wavelengths. Laser fluence was varied from 0.24 to 1.24 J/cm(2). Samples were cleaned by means of 1 and 10 laser shots for each fluence. The effectiveness of cleaning was investigated through measurements of color variations, visual and microscopic observations.

WOS: 000552397100019 Calcite, being the most abundant mineral on earth crust, have wide application areas especially in polymer industry as a micronized functional filler material. It is hydrophilic in natural form, and made hydrophobic after surface modification to meet the requirements of polymer industry: the incompatibility between high energetic hydrophilic surface of calcite and the low-energy surface of hydrophobic polymers is a major problem. Treatment of micronized calcite with fatty acids is one of the most common method to obtain modified mineral surface. In present study, oleic acid (OA), fatty acid type surface modifying agent was used for the surface characterization of OA coated marble dust. Fine tailings of slab cutting unit of a marble processing plant was supplied. The sample was subjected to wet classification process to obtain micronized calcite fraction for experimental works. Surface modification of finely sized fraction was performed in a laboratory type flotation unit. Thermogravimetric analysis (TGA) and Transmission Electron Microscopy (TEM) were used as characterization techniques.

We investigated the structural, compositional, and magnetic properties as well as the AC magnetic hyperthermic response of CoFe 2 - x La x O 4 ( x = 0.0 , 0.2 , 0.5 ) nanoparticles. We found that the La3+ ions substituted into the Fe3+ ion sites, and resulted in an increased magnetocrystalline anisotropy with x, and altered the time-dependent magnetism. To provide a better understanding of the AC magnetic hyperthermia response, a series of temperature versus time measurements were done by varying the magnetic field amplitude, the carrier medium viscosity and the concentration of the nanoparticles as parameters that governed the heating efficiency. A decrease of specific loss power was observed with an increase of the viscosity of the carrier medium for x = 0 and x = 0.25 substituted Co-ferrite nanoparticles, while a small increase was observed with the x = 0.1 La3+ substituted Co-ferrite nanoparticles (due to their higher intrinsic magnetocrystalline anisotropy).

WOS: 000414903800010 In the treatment of dermal wounds, wound-dressing materials prepared from natural mucopolysaccharides are widely used because of their advantages such as nonirritation, nontoxicity, and ease in topical application. In the present study, alginate hydrogels modified with N-acetyl glucose amine (NAG) were prepared as wound-dressing material. Physical, chemical, thermal, and mechanical properties of the hydrogels were studied. Cytotoxicity of the hydrogels on endothelial (HUVEC) and keratinocyte (HaCaT) cells were examined. Anti-and proinflammatory cytokine levels of human monocyte-macrophage cells (THP-1) stimulated with hydrogels were determined. According to the results, increasing the NAG concentration led to an increase in the swelling and nitrogen ratios in the hydrogels. Additionally, increasing the NAG concentration decreased elastic modulus and degradation time. Hydrogels were not cytotoxic on HaCaT and HUVEC cells. It stimulated IL-10 and TNF-alpha levels at a small rate. Scientific Research Department of Hacettepe UniversityHacettepe University [FHD - 2015 - 5348] This work was supported by the Scientific Research Department of Hacettepe University. The project number is FHD - 2015 - 5348.

In this study, the ac magnetic hyperthermia responses of spinel CoFe2O4, MnFe2O4, and NiFe2O4 nanoparticles of comparable sizes (similar to 20 nm) were investigated to evaluate their feasibility of use in magnetic hyperthermia. The heating ability of EDT-coated nanoparticles which were dispersed in two different carrier media, deionized water and ethylene glycol, at concentrations of 1 and 2 mg/mL, was evaluated by estimating the specific loss power (SLP) (which is a measure of magnetic energy transformed into heat) under magnetic fields of 15, 25, and 50 kA/m at a constant frequency of 195 kHz. The maximum value of SLP has been found to be similar to 315 W/g for CoFe2O4 and similar to 295 W/g for MnFe2O4 and NiFe2O4 nanoparticles. We report very promising heating temperature rising characteristics of CoFe2O4, MnFe2O4, and NiFe2O4 nanoparticles under different applied magnetic fields that indicate the effectiveness of these nanoparticles as hyperthermia agents.

Nanoscale pure LiCoPO4 and LiCoPO4/C materials were successfully synthesized as excellent quality cathode materials for high-voltage and high energy density lithium-ion applications. These materials are simply produced by combined magnetron power and the solvothermal method followed by heat treatment. Analyses show that distribution of a surface coated with carbon, 5⿿7 nm thickness by tannic acid and nanostructured LiCoPO4/C cathode exhibits a higher and stable reversible capacity (155.2 mAh g⿿1) with the long voltage plateau nearly 4.8 V. Furthermore, this cathode exhibits capacity retention as 91% after 80 cycles and this value makes it one of the highest of those reported to date. The LiCoPO4/C electrode is produced simultaneously under high pressure and using microwave energy and this has an influence on excellent cycling behavior. The obtained results prove that a production dynamics in nano-synthesis and coating process with proper carbon source reveal parameters to synthesis favorable cathode materials.

In this work, the structural, electrical, magnetic and magneto-caloric properties of the La0.70Ca0.21Ag0.09MnO3 compound were investigated. The compound was prepared by the sol gel method and sintered at 1000 degrees C for 24 h. Powder X-ray diffraction pattern (XRD) analyzes reveals a single phase orthorhombic structure with the Pnma space group as shown by the Rietveld analysis. The grainy morphology was confirmed with a grain size variation of 0.5-1.5 mu m by using scanning electron microscopy (SEM) and atomic force microscopy (AFM) images. High resolution transmission electron microscopy (HR-TEM) results strongly support an orthorhombic structure with the parameters calculated from the XRD data. Ferromagnetic-paramagnetic phase transitions occur at similar to 263 K (Curie temperature, TC) and similar to 265 K (metal-insulator, T-MI). The sample undergoes a sharp metaleinsulator transition at TMI following the sharp paramagneticeferromagnetic transition TC. From the isothermal magnetization measurements (M-H), the maximum magnetic entropy change jDSMj was calculated to be similar to 4.8 J/kgK for an applied field change of 1 T, which is greater than that of pure Gd. (C) 2016 Elsevier B.V. All rights reserved.

The past 30 years have seen spectacular progress in the development of techniques for measuring the complete temporal field, and even the complete spatiotemporal field, of ultrashort laser pulses. The challenge has been to measure a pulse without the use of a shorter event or an independent known reference pulse, neither of which is typically available. We begin with autocorrelation, the first such “self-referenced” pulse-measurement method ever proposed, which measures only a rough pulse length, and we describe its limitations. One such limitation is the presence of a somewhat unintuitive “coherent artifact,” which occurs for complicated pulses and also when averaging over a train of pulses whose shapes vary from pulse to pulse. We then describe the most important modern techniques capable of measuring the complete temporal intensity and phase of even complicated ultrashort pulses, as well as their ability (or inability) to measure such unstable pulse trains. A pulse reliably measured with such a device can then be used as a reference pulse in conjunction with another technique, such as spectral interferometry or holography, to measure pulses otherwise unmeasurable by a self-referenced technique. Examples include techniques for measuring low-intensity pulse(s) and for measuring the complete spatiotemporal intensity and phase of arbitrary pulse(s). This Tutorial is limited to well-established, proven methods, but other methods whose description proves instructive will be discussed.

Microbial accumulation in materials used in sectors such as medical, textile and food can lead to serious diseases, infections and uncontrollable problems. Many of the materials used in the above-mentioned industries have highly sensitive surfaces for microorganisms and cause colonization and biofilm formation. Colonization and biofilm formation threaten human health and they cause many diseases that result in death every year. Antimicrobial materials have an important role in combating pathogens. This article is about a new material with antibiofilm and antimicrobial properties combining polyurethane and Hypericum perforatum extract (PHPE) together. Antimicrobial effect of H. perforatum extract was determined against three clinical pathogens; C. albicans, E. coli and S. aureus. The highest antimicrobial activity of H. perforatum extract was found against S. aureus strain. Antibiofilm analysis results revealed that H. perforatum was also inhibited by the biofilm formation of S. aureus by 56.85%. The combination of polyurethane material and H. perforatum extract (PHPE) resulted in 92.85% decrease in S. aureus biofilm compared to control group. The reduction of S. aureus after H. perforatum incorporation was revealed by Scanning Electron Microscopy (SEM) study. The results show that the polyurethane material combined with H. perforatum extract inhibits the formation of S. aureus biofilm.

Sophisticated modeling of propagation of ultrashort laser pulses with spatio-temporal coupling through transparent medium has enabled reproducing the effect of directional asymmetry in direct laser writing and gaining a deep insight into the underlying physics.

Structural, electrical, and magnetic properties of La0.65(Ca0.30Pb0.05)Mn0.90Cu0.10O3 compound were investigated. The compound, prepared by the sol–gel route, was pressed into pellets and one of them was sintered at 900 °C and the other at 1000 °C for 24 h. The aim of the study was to explore structural, electrical and magnetic properties of the compound. Temperature dependent X-ray powder diffraction studies on the sample sintered at 900 °C reveal an orthorhombic-Pbnm perovskite structure through the temperature range between 320 K and 86 K. Scanning electron microcopy and energy dispersive spectroscopy analyses showed grainy, homogeneous and stoichiometric structure. Magnetization and resistivity measurements reveal that the Curie temperatures, TC, and insulator–metal transition temperatures, TIM, coincide, but the samples sintered at 900 °C also exhibit thermal hysteresis both in magnetization and resistivity upon cooling and warming.

4th International Congress in Advances in Applied Physics and Materials Science (APMAS) - APR 24-27, 2014 - Fethiye, TURKEY

The La0.65Ca0.30Pb0.05Mn0.9B0.1O3 (A = Co, Ni, Cu and Zn) manganites have been prepared via sol–gel method and sintered at 1100 °C for 24 h. The aim of the study was to investigate B-site cation doping effects on the magnetic properties. XRD analysis reveals that all samples have rhombohedral structure belonging to the R 3 ‾ c space group. The Curie temperature decreases as a result of Mn replacement with Co, Ni, Cu and Zn, respectively. The maximum magnetic entropy changes of the samples doped with Co, Ni, Cu and Zn for a field change of 1 T were found to be 2.10, 1.71, 3.20 and 1.42 J/kg K respectively. For La0.65Ca0.30Pb0.05MnO3, this is 2.60 J/kg K. The maximum magnetic entropy change increases as a result of Cu doping. Additionally, the metal–insulator transition temperature decreases due to the B-site doping.

WOS: 000346703800043, The structural, electric, and magnetic properties of La1-xNaxMnO3 (0.05

In droplet based microfluidics, ability of controlling the motion of the droplets insidechips have great importance for the applications such guiding, sorting, mixing and dividing of liquid droplets. In this study, we fabricated hydrophilic microchannels inside the chips by femtosecond laser ablation technique in order to control droplet motion. The laser beam focused on PDMS converts the irradiated regions to hydrophilic by ablating the coating entirely from the surface. Droplets follow the tracks because of the difference in wettability of ablated region and PDMS surfaces together with the topographical profile of the ablated tracks. Within this study, we investigated the manipulation of three kind of liquid droplets (water/surfactant mixture, pure water and pure etylene glycol) along microchannels with depths of 1μm, 1.5μm and 2μm. We verified the experimental results with simulations and analyzed the trajectories of the moving droplets with the different wettability along the tracks of different depths. Our results showed that, while topographical effects play role in droplet guiding for 1.5μm and 2μm tracks, for the case of 1μm depth of channel, surface energy modifications cause the guiding rather than the topographical step on the surface. These results will pioneer for sorting applications of different micro droplets mixed in the same microfluidic chip.

WOS: 000407441700003 PubMed ID: 28675984 Vitamin D3 (VitD3) has several beneficial effects on many metabolic pathways such as immunity system, bone development. The aim of the study, encapsulation of VitD3 with solid lipids, determine encapsulation efficiency and biocompatibility of nanoparticles. Therefore, VitD3-loaded solid lipid nanoparticles (SLNPs) were developed by optimising ratios of VitD3, stearic acid, beeswax and sodium dodecyl sulphate (SDS). Thermal stability, degradation profile, crystallinity rate, encapsulation efficiency and release profile of SLNPs were determined. Cytotoxicity of SLNPs on HaCaT, L929 and HUVEC cells were investigated. Negatively charged and VitD3-loaded nanoparticles with diameters between 30 and 60 nm were obtained. SLNPs containing up to 5.1 mg VitD3 per 10 mg powder samples were obtained. Cell proliferations were stimulated after exposure with VitD3-loaded SLNPs. Besides, inflammatory response after exposure to VitD3-loaded SLNPs was evaluated via determining IL10 and TNF-alpha levels on THP-1 cells. According to the results, no inflammatory response was observed. Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [115Z018] This study was supported by the Scientific and Technological Research Council of Turkey (TUBITAK) and the project number is 115Z018.

We demonstrate controlled guiding of nanoliter emulsion droplets of polar liquids suspended in oil along shallow hydrophilic tracks fabricated at the base of microchannels located within microfluidic chips. The tracks for droplet guiding are generated by exposing the glass surface of polydimethylsiloxane (PDMS)-coated microscope slides via femtosecond laser ablation. The difference in wettability of glass and PDMS surfaces together with the shallow step-like transverse topographical profile of the ablated tracks allows polar droplets wetting preferentially the glass surface to follow the track. In this study, we investigate guiding of droplets of two different polar liquids (water/ethylene glycol) with and without surfactant suspended in an oil medium along surface tracks of different depths of 1, 1.5, and 2 $$\upmu$$ m. The results of experiments are also verified with computational fluid dynamics simulations. Guiding of droplets along the tracks as a function of the droplet composition and size and the surface profile depth is evaluated by analyzing the trajectories of moving droplets with respect to the track central axis, and conditions for stable guiding are identified. The experiments and numerical simulations indicate that while the track topography plays a role in droplet guiding using 1.5- and 2- $$\upmu$$ m deep tracks, for the case of the smallest track depth of 1 $$\upmu$$ m, droplet guiding is mainly caused by surface energy modification along the track rather than the presence of a topographical step on the surface. Our results can be exploited to sort passively different microdroplets mixed in the same microfluidic chip, based on their inherent wetting properties, and they can also pave the way for guiding of droplets along reconfigurable tracks defined by surface energy modifications obtained using other external control mechanisms such as electric field or light.

The influence of beam intensity on laser ablation quality and ablation size is experimentally studied on graphene-coated silicon/silicon dioxide substrates. With an amplified femtosecond-pulsed laser system, by systematically decreasing the average power, periodic stripes with decreasing widths are ablated. Histogram analyses of the untouched and ablated regions of scanning electron microscope images of the fabricated structures make it possible to quantify the ablation quality. These analyses reveal that submicron ablation can be achieved while maintaining 75 % ablation accuracy by adjusting the beam intensity around the ablation threshold.

Lasers have served as cleaning tools for historical objects and artworks for about 40 years. In many cases, superior results of laser cleaning were achieved with respect to traditional methods. In this technique, contaminations on the surface of the object are ablated by laser irradiation. In order to apply laser cleaning method to fragile materials such as paper made of cellulose or parchment, heat deposition to the bulk should be minimal, to prevent damage. In this work, it is demonstrated that laser pulses with femtosecond (fs) duration can exhibit non-thermal ablation of contaminants on paper samples. In particular, laser cleaning studies are concentrated on paper samples with sizing. Fs laser cleaning is performed on artificially soiled and aged samples, as well as on historical ones. The laser used in the experiments has pulse duration of 550 fs and 1030 nm center wavelength. The fluence of the laser is varied and the post-cleaning statuses of samples are investigated. The analyses are color changes, fiber integrity, chemical composition changes and mechanical strengths. These results show that fs lasers can be very efficient in cleaning paper samples, yielding minimal discoloration and no damage to fibers distinguishable on microscopic examination. The presence of sizing also provides further protection against possible side effects.

In this work we investigated structural, magnetic and transport properties of La0.70Sr0.21K0.09MnO3 compound produced by the standard sol-gel route. The crystal structure was determined by analyzing XRD data and found to be an orthorhombic perovskite belonging to Pnma space group. The Curie temperature, T-C, of the compound was determined to be 295 K, which is near room temperature. The calculated magnetic entropy change was 0.77 J/kg K which is not high enough for magnetic cooling application. Insulator-Metal transition temperature, T-IM, was determined to be 294 K, which coincides with T-C. The low temperature peak near T-IM reveals the coexistence of ferromagnetic and paramagnetic phases in the ferromagnetic region. The temperature dependence of resistivity was well fitted (with R-2 = 0.9999) to rho(T) = rho(0) + rho T-0.5(0.5) + rho T-2(2) + rho T-4.5(4.5) in a wide temperature interval including low temperature resistivity upturn. (C) 2013 Elsevier B. V. All rights reserved.

3rd International Congress on Advances in Applied Physics and Materials Science - APR 24-28, 2013 - Antalya, TURKEY

Numerous experimental studies in recent years have revealed intriguing symmetry breakings during non-linear interaction of ultrashort laser pulses with materials. Dependence of the formed structures on the direction of laser scanning and polarization, an effect known as non-reciprocal writing, is one of the most commonly observed asymmetries. These observations are generally attributed to spatio-temporal couplings (primarily pulse-front tilt) in the laser pulses. Even though such couplings indeed break the spatial symmetry of the light–matter interactions, a detailed understanding of ongoing phenomena in the microscopic level is still lacking. In this work, we present our theoretical results, which, to the best of our knowledge, constitute the first demonstration of the physical mechanisms behind non-reciprocal writing and related effects in transparent media. Our model is based on non-linear Maxwell’s equations supplemented by the hydrodynamic equations for free electron plasma, and rate equations for the evolution of defects inside the material. It has enabled us to gain a qualitative insight into the features of propagation of ultrashort laser pulses with tilted pulse fronts, in the regimes of volumetric laser modification of transparent materials.

This is a corrigendum for the article 2015 J. Opt. 17 105903 https://doi.org/10.1088/2040-8978/17/10/105903

We experimentally investigate propagation of laser beams with different intensity profiles in highly scattering media. We generate transverse laser amplitude profiles with Gaussian, Bessel and Airy function envelopes. We then propagate these beams through optical phantoms formed with variable density intralipid solutions. At the sample exit, we compare change in maximum intensities, as well as beam profile reconstruction. We show that self-reconstruction properties of Bessel and Airy beams bring about slower decrease in maximum intensity with increasing scatterer density. On the other hand, the beam profiles deteriorate faster, as compared to reference Gaussian beams. Slower decrease in the intensity can be attributed to the wavevector spectra providing a continuous flow of energy to the beam center, while beam deterioration is linked to total beam volume in the scattering medium. These results show that beam shaping methods can significantly enhance delivery of intense light deeper into turbid media, but this enhancement is compromised by stronger speckling of beam profiles.

In this work, 16 nm indium nitride (InN) nanoparticles (NPs) are used to increase the performance of thin-film c-Si HIT solar cells. InN NPs were spin-coated on top of an ITO layer of c-Si HIT solar cells. The c-Si HIT cell is a stack of 2 mu m p type c-Si, 4-5 nmn type a-Si, 15 nm n(+) type a-Si and 80 nm ITO grown on a p(+) type Si substrate. On average, short circuit current density (J(sc)) increases from 19.64 mA cm(-2) to 21.54 mA cm(-2) with a relative improvement of 9.67% and efficiency increases from 6.09% to 7.09% with a relative improvement of 16.42% due to the presence of InN NPs. Reflectance and internal/external quantum efficiency (IQE/EQE) of the devices were also measured. Peak EQE was found to increase from 74.1% to 81.3% and peak IQE increased from 93% to 98.6% for InN NPs coated c-Si HIT cells. Lower reflection of light due to light scattering is responsible for performance enhancement between 400-620 nm while downshifted photons are responsible for performance enhancement from 620 nm onwards.

We have investigated structural, magnetic, and magnetocaloric properties of monovalent Ag-doped La1−x Ag x MnO3 (0.05 ≤ x ≤ 0.25) compounds. The materials were prepared by the sol–gel method and then characterized by X-ray diffraction (XRD). The XRD results indicated that all the samples have a single phase of hexagonal (rhombohedral) structure with the $R\overline {\text {3}} c$ space group. The morphology and particle size distributions were investigated using scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS). The SEM images showed that the grain sizes are smaller than 1 μm and remain the same with increasing Ag concentrations. The magnetic properties were studied by measuring magnetization and varying temperature (M(T)) and external magnetic field (M(H)). The M(T) measurements show that with decreasing temperature all samples exhibit a paramagnetic-to-ferromagnetic phase transition. The Curie temperature, T C, increases from 200 to 290 K as Ag doping increases from 0.05 to 0.25. The magnetic entropy change (|−SM|) is obtained in all samples near the Curie temperatures at a magnetic field change of 3 T. Furthermore, their maximum relative cooling power (RCP) values were found to be 82.492, 82.614, and 127.375 J/kg for x = 0.10, 0.15, and 0.25.

CeMn2Ge2 nanopowders have been obtained by high-energy ball milling for 5 and 10 hours from bulk compound to investigate the effect of milling time on magnetic and magnetocaloric properties. CeMn2Ge2 nanopowders have been characterized by X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy, transmission electron microscopy, and magnetization measurements. The average grain size of the nanoparticles from XRD measurements is about 12.2 and 8 nm for 5-hour and 10-hour ball-milled samples, respectively. The investigations reveal that magnetic entropy change (∆S m) can be altered by changing the particle size of the compound. Maximum ∆S m is −2.45 and −1.30 J kg−1 K−1 for the 5- and 10-hour ball-milled nanopowders, respectively.

We fabricated Si Nano-columns by a femtosecond laser with various wavelengths and process parameters, whilst the specimen was submerged in water. The experiments were carried out by three types of wavelengths i.e. 1030 nm, 515nm, 343nm, with 500 fs laser pulses. The scales of these spikes are much smaller than micro spikes that are constructed by laser irradiation of silicon surface in vacuum or gases like SF6, Cl2. The Si nano-columns of 300 nm or less in width were characterized by SEM measurements. The formation of these Si Nano-columns that were revealed by SEM observation, indicates chemical etching with laser ablation occurred when surface exposed by laser beam. We observed 200 nm spikes height at the center of laser beam profile and the ones uniform in height at lateral incident area.

We investigate the effect of sintering temperature on the structural and magnetic properties of La 1.4 Ca 1.6 Mn 2 O 7 double perovskite manganite compound prepared by the sol–gel route. Three sintering temperatures (1273, 1473 and 1673 K) are utilized for the heat treatment. Regardless of the sintering temperature, the tetragonal crystal structure with the I 4/ mmm space group is stable. However, a reduction in a and an increase in c lattice parameters along with a significant increase in crystallite-size occur on increasing the sintering temperature. This is also accompanied by the growth of grains. Grain-growth and changing crystallite-sizes account for the changes in magnetization, Curie temperature and magnetic entropy-change values. As the sintering temperature increases from 1273 to 1673 K the Curie temperature increases from 225 to 268 K and the magnetic entropy-change increases from 0.58 to 3.1 J kg −1 K −1 respectively.

La 1− x Ag x MnO 3 samples were synthesized by standard sol–gel method with Ag concentrations of x =0.05 and 0.25. The samples from each concentration were pressed and sintered at 1000, 1200 and 1400 °C for 24 h in air for a systematic study. They were examined structurally by Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDS) and X-ray Diffraction (XRD) and magnetically by Magnetic Properties Measurements System (MPMS). AFM and SEM analyses show that surface morphology changes with Ag concentration and sintering temperature ( T S ). It was observed that high temperature sintering leads Ag to leave material as determined from EDS analyses. XRD spectra exhibited that the crystal structure changes with Ag concentration while showing pronounced change with the sintering temperature. From the magnetic measurements, the Curie temperatures ( T C ) and the isothermal magnetic entropy changes (−ΔSM) were calculated. It was observed that T C increases with Ag concentration and decreases with T S . The maximum −ΔSM was calculated to be 7.2 J/kg K under the field change of 5 T for the sample sintered at 1000 °C with x =0.25.

0000-0002-3081-0691 WOS: 000418383300001 The microstructure, composition and magnetism of CoFe2O4, MnFe2O4 and NiFe2O4 nanoparticles of comparable sizes (similar to 20 nm) and interparticle spacings (similar to 20 nm) have been characterized from 10 to 400 K. The cation distributions of the tetrahedral and octahedral sites of the particles, that have cubic spinel structures, have a high degree of inversion, similar to 0.98 for CoFe2O4, similar to 0.80 for MnFe2O4 and NiFe2O4 nanoparticles. The blocking temperatures were similar to 300 K for the MnFe2O4 and NiFe2O4 nanoparticles, while the CoFe2O4 nanoparticles, due to their higher intrinsic anisotropy had a significantly higher blocking temperature above 400 K. Specifically, the magnetocrystalline anisotropy of the CoFe2O4 nanoparticles was K = ( 2.96 +/- 0.03) x 10(6) ergs cm(-3), while for the MnFe2O4 nanoparticles, K = ( 0.04 +/- 0.01) x 10(6) ergs cm(-3), and for the NiFe2O4 nanoparticles, K = ( 0.07 +/- 0.01) x 10(6) ergs cm(-3). The magnetism of these three ferrite systems are discussed in detail with regards to their microstructures and cation distributions. Mugla Sitki Kocman UniversityMugla Sitki Kocman University [14/066] The authors thank the Scientific and Technological Research Council of Turkey (TUBITAK) and Natural Sciences and Engineering Research Council of Canada (NSERC). This paper has been granted by the Mugla Sitki Kocman University Scientific Research Project Coordination through Project Grant Number: (14/066).

International audience; By immersing a conventional glass axicon in index-matching liquid, we generated high quality, tunable, quasi-non-diffracting Bessel beams. The aberrations resulting from the roundness of the axicon tip are minimized when a large base angle is used in liquid-immersion. This configuration also allows coarse and fine tunability through changing the liquid and adjusting the temperature, respectively. Our experimental results match very well with calculated intensity profiles. We succeeded to generate two-meter long plasma channels in air by focusing femtosecond laser pulses with the liquid-immersion axicon.

We describe experimentally simple, accurate, and reliable methods for measuring from very simple to potentially very complex ultrashort laser pulses. With only a few easily aligned components, these methods allow the measurement of a wide range of pulses, including those with time-bandwidth products greater than 1000 and those with energies of only a few hundred photons. In addition, two new, very simple methods allow the measurement of the complete spatio-temporal intensity and phase of even complex pulses on a single shot or at a tight focus.

International audience; We show that by focusing ultrashort-pulsed laser beams in air with an axicon, relatively long plasma channels can be generated. The axicon generates Bessel-like beams, where the on-axis intensity stays high over distances much longer compared to focusing with conventional lenses. We developed a scheme to detect the presence of the plasma, based on its screening property. Using this scheme, we detected plasma channels longer than 1 m and 3.5 m generated by 8 mJ and 90 mJ input pulse energies, respectively. Our simulations show that axicon focusing can yield self-guided propagation with or without contribution of plasma, depending on the input pulse power.

We discussed two main approaches for generation of nanometer-scale structures using pulsed lasers. In the first, a bulk material is ablated in vacuum, gas or liquid and consequent re-solidification of the evaporated material in clusters generate the desired nanoparticles. While one can play with various experimental parameters (laser powers, type of liquids, background gas etc.) to control particle sizes, there is always a relatively broad distribution of particle sizes. Nevertheless, particles with sizes down to few nanometers are achievable. In the second approach, fs lasers are used to pattern material surfaces. This process is more controlled in the sense that the desired geometries are generated by scanning of the sample. On the other hand, best achievable resolutions are worse as compared to the former approach. Resolutions better than 100 nm over large surfaces is very difficult. Finally, special beam shaping methods forms an interesting frontier in pushing forward the fs laser nanomachining methods towards broader practical uses.

In this work, we present a hybrid indium nitride particle/polycrystalline silicon solar cell based on 230 nm size indium nitride particles (InN-Ps) obtained through laser ablation. The solar cell performance measurements indicate that there is an absolute 1.5% increase (Δη) in the overall solar cell efficiency due to the presence of InN-Ps. Within the spectral range 300-1100 nm, improvements of up to 8.26% are observed in the external quantum efficiency (EQE) and increases of up to 8.75% are observed in the internal quantum efficiency (IQE) values of the corresponding solar cell. The enhancement in power performance is due to the down-shifting properties of the InN-Ps. The electrical measurements are supplemented by TEM, Raman, UV/VIS and PL spectroscopy of the InN-Ps. © 2015 IOP Publishing Ltd.

Laser ablation offers cleaning method for historical and art works effectively. Difference between ablation threshold of contamination layer and the surface yields to remove contaminants from surface without detriment to historical material. In particular, lasers with ultrashort pulse duration are very convenient for brittle historical papers, fibers of which should be intact after cleaning treatment. Since duration of laser irradiation and material interaction is very short, the possibility of damage to the paper is very low. One of the other crucial issues after paper cleaning treatment is color variation on the surface. Authentic color of the historical paper has to be preserved after the procedure. In this paper, we present results of paper cleaning via femtosecond (fs) laser running at a wavelength of 1030 nm. In the first stage of this experimental study, we determined optimum laser parameters on artificially soiled and aged paper samples, then cleaned a handwritten manuscript with ‘sizing’. In calligraphy, ornamentation and miniature arts, sizing is applied on paper as a protective layer which increases strength of paper and renders it more useful. Papers with sizing have been prevalently used in Islamic or Ottoman culture. We observed that after laser irradiation, artificial soling layer is effectively removed, while original color of the subs-layers did not alter. We used scanning electron microscopy (SEM) to examine fiber integrity, and determined that the sizing layer was not removed when optimized parameters were used, thus the fibers were not damaged.

International audience; We investigate experimentally and numerically the nonlinear propagation of intense Bessel–Gauss vortices in transparent solids. We show that nonlinear Bessel–Gauss vortices preserve all properties of nonlinear Bessel–Gauss beams while their helicity provides an additional control parameter for single-shot precision micro structuring of transparent solids. For sufficiently large cone angle, a stable hollow tube of intense light is formed, generating a plasma channel whose radius and density are increasing with helicity and cone angle, respectively. We assess the potential of intense Bessel vortices for applications based on the generation of hollow plasma channels.

We present a new method to form liquid-core optofluidic waveguides inside hydrophobic silica aerogels. Due to their unique material properties, aerogels are very attractive for a wide variety of applications; however, it is very challenging to process them with traditional methods such as milling, drilling, or cutting because of their fragile structure. Therefore, there is a need to develop alternative processes for formation of complex structures within the aerogels without damaging the material. In our study, we used focused femtosecond laser pulses for high-precision ablation of hydrophobic silica aerogels. During the ablation, we directed the laser beam with a galvo-mirror system and, subsequently, focused the beam through a scanning lens on the surface of bulk aerogel which was placed on a three-axis translation stage. We succeeded in obtaining high-quality linear microchannels inside aerogel monoliths by synchronizing the motion of the galvo-mirror scanner and the translation stage. Upon ablation, we created multimode liquid-core optical waveguides by filling the empty channels inside low-refractive index aerogel blocks with high-refractive index ethylene glycol. In order to demonstrate light guiding and measure optical attenuation of these waveguides, we coupled light into the waveguides with an optical fiber and measured the intensity of transmitted light as a function of the propagation distance inside the channel. The measured propagation losses of 9.9 dB/cm demonstrate the potential of aerogel-based waveguides for efficient routing of light in optofluidic lightwave circuits., NA

We report on the fabrication and characterization of versatile light waveguides exploiting filaments of a polar liquid confined within hydrophobic silica aerogels. Aerogels are highly porous materials with extremely low refractive index which makes them suitable as rigid cladding of liquid-core optofluidic waveguides based on total internal reflection of light. In this article, we introduce a new microfabrication technique that allows direct and precise processing of monolithic silica aerogels by ablation with femtosecond laser pulses. Using fast scanning of the focused laser ablation beam synchronized with the motion of the processed aerogel sample, we created high-quality straight microchannels of similar to 5 mm length with controlled cross-sections inside monolithic aerogels. After the ablation, we filled the channels with high-refractive index ethylene glycol, forming multimode liquid core - solid cladding optofluidic waveguides. Subsequently, we carried out light-guiding experiments to measure overall optical attenuation of these waveguides. The characterization of waveguide transmission yielded values of propagation losses lower than 10 dB cm(-1), demonstrating that the liquid-core waveguides with laser-ablated aerogel cladding represent an attractive alternative in optofluidic applications targeting controlled routing of light along arbitrary three-dimensional paths. (C) 2015 Elsevier B.V. All rights reserved.

Femtosecond lasers can provide submicron ablation resolution, making them suitable and attractive for various micro/nanofabrication applications. Laser beam shaping lends further advantages and increases the versatility of these sources. In this work, we report on the use of femtosecond laser pulses with first-order Bessel function (Bessel vortex) beam profiles in ablation of metal thin films. The diffraction-free nature of Bessel beams provides significant convenience regarding alignment and repeatability. Ablation profiles with Bessel vortex beams generally consist of single or multiple concentric rings, determined by pulse fluence on target. We investigate single-pulse ablation behavior with two laser wavelengths (1,030 and 515 nm) and three different Bessel beam cone angles. For each case, we measure inner and outer ring diameters and compare our results with theoretical calculations.

We have systemically studied the effects of annealing temperature and alloy composition on the structural and magnetic properties of bulk Ni$_{2}$MnGe and Ni$_{2.1}$Mn$_{0.9}$Ge Heusler alloys. We have observed that both annealing temperature and the alloy composition drastically alter the phases found in the samples due to the presence of competing ternary phases. Annealing at 900 and 950 $^{\circ}$C for both alloy compositions facilitate the formation of L2$_{1}$ Heusler phase. Nevertheless, formation of Ni$_{5}$Mn$_{4}$Ge$_{3}$ and Ni$_{16}$Mn$_{6}$Ge$_{7}$ phases cannot be prevented for Ni$_{2}$MnGe and Ni$_{2.1}$Mn$_{0.9}$Ge alloys, respectively. In order to estimate the magnetic contribution of the Ni$_{5}$Mn$_{4}$Ge$_{3}$ impurity phase to that of the parent Ni$_{2}$MnGe, we have also synthesized pure Ni$_{5}$Mn$_{4}$Ge$_{3}$ alloy. Antiferromagnetic nature of Ni$_{5}$Mn$_{4}$Ge$_{3}$ with low magnetization response allows us to reveal the magnetic response of the stoichiometric bulk Ni$_{2}$MnGe. Bulk Ni$_{2}$MnGe shows simple ferromagnetic behavior with a Curie temperature of 300 K, in agreement with the previous results on thin films. Despite the divergence of magnetization curves between field cooled (FC) and field heated (FH) modes, stoichiometric Ni$_{2}$MnGe alloy does not undergo a martensitic phase transition based on our variable temperature x-ray diffraction experiments., Comment: 6 pages, 9 figures; to appear in Journal of Alloys and compounds

Oksuzomer, Faruk/0000-0003-0827-8667; Koc, Serkan Naci/0000-0003-4472-4337 WOS: 000242522000015 LaAlO3 powders are prepared by sol-gel method. The effect of preparation conditions on morphological properties and crystal formations are investigated. iso-Propanol/tert-butanol and ethyl acetoacetate/ethylene glycol monomethylether are used solvents and complexing agents, respectively. Samples are dried with conventional and freeze-drying methods and calcined between 600 and 1000 degrees C. TGA, DTA, XRD, SEM and TEM methods are used for characterization. It is observed that freeze-dried sample prepared with tert-butanol has the lowest LaAlO3 formation temperature and uniform rhombohedral crystals. But conventionally dried sample, prepared with iso-propanol has smallest agglomerates at 1000 degrees C and does not show clear crystallization temperature in DTA analysis. The XRD peaks of LaAlO3 crystal are observed at 600 degrees C for all samples prepared by various sol-gel conditions. (C) 2006 Elsevier Ltd. All rights reserved.

Spatial chirp is a common spatio-temporal effect, but its parameterization is currently unsatisfactorily vague. In this paper, we propose and compare two definitions of spatial chirp, which we call “spatial dispersion” and “frequency gradient.” The appropriate definition to use depends on the application. For Gaussian beams and pulses, the relationship between the two definitions is found to be analogous to that between the definitions of temporal chirp in the time and frequency domains.

Electromagnetic wave propagation through and reflection from grating-like structures is one of the very fundamental and most studied subjects both in electromagnetics and optics. Several theoretical models and numerical solvers have been developed in order to solve this problem as efficiently and accurately as possible for different applications. In this work we experimentally study such phenomenon on metal nano stripe arrays fabricated with femtosecond laser ablation and compare our experimental findings with a full-wave time domain electromagnetic solver.

Two new Cu(II) complexes of Schiff base-hydrazone ligands, hydroxy-N′-[(1Z)-1-(4-hydroxyphenyl)ethylidene]benzohydrazide [H3L1] and ethyl 2-(4-(1-(2-(4-(2-ethoxy-2-oxoethoxy)benzoyl)hydrazono)ethyl)phenoxy)acetate (HL2) have been synthesized and then characterized by microcopy and spectral studies. X-ray powder diffraction illustrates that [Cu(L2)2] complex is crystalline in nature whereas [Cu(H2L1)2]·2H2O has an amorphous structure. Binding of the copper complexes with Calf thymus DNA (CT-DNA) has been investigated by UV-visible spectra, exhibiting non-covalent binding to CT-DNA. DNA cleavage experiments have been also investigated by agarose gel electrophoresis in the presence and absence of an oxidative agent (H2O2). The effect of complex concentration on the DNA cleavage reaction has been also studied. Both copper complexes show nuclease activity, which significantly depends on concentrations of the complexes, in the presence of H2O2 through oxidative mechanism whereas they slightly cleavage DNA in the absence an oxidative agent.

We report on the preparation and characterization of free-standing optofluidic waveguides created on solid superhydrophobic (SH) substrates with patterned wetting properties. In order to locally modify the liquid-solid contact angle, we employed selective laser ablation of SH layers deposited on magnesium-fluoride substrates with low refractive index. Upon ablation, surfaces with hydrophilic channels surrounded by SH areas were obtained. Subsequently, we created liquid optical waveguides based on total internal reflection using ethylene glycol, a polar liquid with high refractive index spreading spontaneously along the hydrophilic surface channels. We evaluated the light guiding performance and losses of these optofluidic waveguides. (C) 2014 AIP Publishing LLC., Scientific and Technological Research Council of Turkey (TÜBİTAK); Turkish Academy of Sciences (Turkish Academy of Sciences (TÜBA) GEBİP)

3rd International Congress on Advances in Applied Physics and Materials Science - APR 24-28, 2013 - Antalya, TURKEY WOS: 000339825400067 Recently, so-called "phenol-formaldehyde-urea resins", which are generally made only by mechanical blending of UF resin and alkaline type PF resins, have been used as adhesives for the manufacturing of wood products. Faster curing PF resins can be also prepared by the addition of urea during or after the resin synthesis to yield co-condensed phenol-urea-formaldehyde (PUF) resins. In this study, resin/clay composites were prepared by in situ polymerization of phenol(18.2%)-urea(36.3%)-formaldehyde(45.5%) (PUF) with the various ratios of organoclay (7.69-45.45%) and colored organoclay (3.22-20.0%). The objective of our work is the investigation of the effect of addition of both organoclay and colored organoclay at different ratios on the textural characteristics. The composites are characterized by X-ray diffraction, Fourier transform infrared spectroscopy techniques and using high resolution transmission electron microscopy images of the samples. It was found that clay layers exfoliated in the resin matrix. Doga Nanobiotech Inc, Mega Technol Serv Inc