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Periodic structures can be created in LC-based composite confined in 1D space when it is heated to phase transition temperature. Photopolymerization is used to stabilize the observed anisotropic structures.

Black body radiation sources are commonly used devices in areas related to thermal imaging and radiometry. They are the closest physical approximation of theoretical black body emitter derived from the Planck’s law. Majority of such devices are costly with restricted information about their production technology, including their emitter surface. A few relatively easily accessible coatings with potential application in such devices have been chosen and their emissivity measured. The paper presents measurements that provides information necessary to determine whether there are coatings viable for black body emitter or reference surface.

Titanium dioxide (TiOUV-Vis absorption spectroscopy allowed us to investigate the pigment purity and determined the polymorph form in pigments. FTIR was employed to identify functional groups present in the samples with the modified surface. XRD, DLS , TEM and DCS were applied to characterize particle size and morphology. The experiment of ED-XRF method was used to determine the elemental composition of pigments that differ in their behavior in a cosmetic formulation.UV-Vis spectroscopy was used to detect organic pollutants in particular batches, which were not detected in the cases of the tested samples. Solid UV-Vis spectroscopy and XRD revealed which crystalline form of TiOOur data indicate how we can recognize poorly coated pigments in raw material. The results show that ED-XRF method is nondestructive, effective and fast, hence, can be successfully introduced into preproduction pigment control in cosmetic industry.

The advancement of analytical methods for nanoparticle measurements is critical both for the growing industrial exploitation of engineered nanoparticles and for developing robust strategies to understand and control the concentration of nanomaterials in humans and the environment. For high value nanoparticles, the measurement of nanoparticle number concentration in a liquid directly impacts the ability to assess the scale and reproducibility of the production process, it allows optimisation of efficiency and supports regulatory compliance. This measurement is also useful to monitor and control the intentional or accidental release of engineered nanoparticles into the environment at the production plant, as well as by end-users., peer-reviewed

This paper presents the results of investigations of the effect of graphene oxide and surface shot peening on the mechanical properties and fatigue life of bolts made of austenitic 304 steel. An innovative method for the uniform deposition of graphene oxide on screws is presented. The process involved activating the surface using plasma and then performing graphene oxide deposition using centrifugal force and vacuum drying. The screw specimens prepared in this way were subjected to a surface peening process. Comparative studies have shown that the combination of graphene oxide deposition and shot peening processes results in an increase in fatigue life of approximately 42 ÷ 275% (depending on the stress amplitude level) compared to the as-delivered samples. The results presented are promising and may provide a basis for further research on the application of graphene and its derivatives to increase fatigue life and improve the mechanical properties of machine components.

The aim of this communication is to describe the range of applications of GaN-based platforms for trace detection and identification of biological and chemical agents using SERS technique. The methods of nano-structuring of GaN surface for SERS application are briefly described. The results of employing SERS method for analysis of Fentanyl and Bacillus Atrophaeus spores is demonstrated. The arguments are summarized which show the universal feature of GaN-based platforms as SERS sensor.

Titanium and its alloys is the main group of materials used in prosthetics and implantology. Despite their popularity and many advantages associated with their biocompatibility, these materials have a few significant disadvantages. These include low biologic activity&mdash, which reduces the growth of fibrous tissue and allows loosening of the prosthesis&mdash, the possibility of metallosis and related inflammation or other allergic reactions, as well as abrasion of the material during operation. Searching for the best combinations of material properties for implants in today&prime, s world is not only associated with research on new alloys, but primarily with the modification of their surface layers. The proposed laser modification of the Ti13Nb13Zr alloy with a carbon nanotube coating is aimed at eliminating most of the problems mentioned above. The carbon coating was carried out by electrophoretic deposition (EPD) onto ground and etched substrates. This form of carbon was used due to the confirmed biocompatibility with the human body and the ability to create titanium carbides after laser treatment. The EPD-deposited carbon nanotube coating was subjected to laser treatment. Due to high power densities applied to the material during laser treatment, non-equilibrium structures were observed while improving mechanical and anti-corrosive properties. An electrophoretically deposited coating of carbon nanotubes further improved the effects of laser processing through greater strengthening, hardness or Young&prime, s modulus similar to that required, as well as led to an increase in corrosion resistance. The advantage of the presented laser modification of the Ti13Nb13Zr alloy with a carbon coating is the lack of surface cracks, which are difficult to eliminate with traditional laser treatment of Ti alloys. All samples tested showed contact angles between 46&deg, and 82&deg, and thus, based on the literature reports, they have hydrophilic surfaces suitable for cell adhesion.

This work reviews different types of surface structures formed on selectively etched GaN substrates for surface-enhanced Raman scattering (SERS) measurements. A one-to-one correlation between nano-structure and SERS efficiency, represented by the enhancement factor (EF), is shown by comparing SEM images with maps of Raman intensity. In this way, the location of hot-spots (H-Ss) is disclosed, leading to the selection of an optimal technology for manufacturing efficient and uniform SERS platforms. GaN platforms with nano-structures containing bunched pillars and pyramids covered with an Au-Ag plasmonic layer reproducibly show an EF of up to 106 for 4-mercaptobenzoic acid (pMBA) test molecules. Platforms with pits (inverted pyramids) yield an EF of one order of magnitude lower.

Raman spectroscopy has become an essential analytical technique for field detection and identification of illicit or dangerous materials such as explosives, but its main drawback is low signal intensity. This problem can be circumvented by using surface enhanced Raman spectroscopy (SERS), in which scattering signals increase significantly for analytes adsorbed onto or near nanostructured surfaces of the plasmonic materials. However, despite numerous studies, SERS has still not been widely used in real-world applications. The main goal of the studies describe herein was to investigate the possibility of detection of trace amounts of selected explosive materials on various commercial and non-commercial SERS substrates using portable Raman instruments. Our studies have shown that while portable systems suitable for SERS measurement of trace amounts of explosives are readily available, the problem remains in the selection of reliable and reproducible SERS substrates. Among five investigated SERS substrates only two, Klarite 312 and GaN-pillars allowed for trace analysis of all studied explosive materials. In both cases, detected concentrations of explosives ranged from single to hundreds of μg/cm2 depending on the explosive material and the Raman spectrometer used. Based on our findings, it could be concluded that the best SERS substrates for trace analysis of explosives are substrates with hot spots densely and evenly distributed over a whole active area of SERS substrate.

The graphene paper microsieves can be applied in the filtration of biological fluids or separation of solid particles from exploitation fluids. To produce graphene paper microsieves for specific applications, good control over fabrication should be achieved. In this study, a laser ablation method using a picosecond laser was applied to fabricate graphene paper microsieves. Holes in the microsieves were drilled using pulsed laser radiation with a pulse energy from 5 to 100 &micro, J, a duration of 60 ps, a wavelength of 355 nm, and a repetition rate of 1 kHz. The impact method was applied using 10 to 100 pulses to drill one hole. To produce holes of a proper diameter which could separate biological particles of a certain size (&ge, 10 &micro, m), optimum parameters of graphene paper laser ablation were defined using the MATLAB software taking into account laser pulse energy, repetition rate, and a desired hole diameter. A series of structural tests were carried out to determine the quality of an edge and a hole shape. Experimental results and Laguerre&ndash, Gauss calculations in MATLAB were then compared to perform the analysis of the distribution of diffraction fringes. Optimum experimental parameters were determined for which good susceptibility of the graphene paper to laser processing was observed.

Optical properties of photonic crystal fibers (PCFs) as well as micro-capillaries infiltrated with a 6CHBT liquid crystal (LC) doped with spherical silver (Ag) nanoparticles (NPs) have been studied. Three different concentrations of Ag NPs dopants were taken into consideration and their presence in the 6CHBT LC was found to modify the spectral properties of the infiltrated PCF. A significant improvement of switching times was observed for the NPs-doped LC-infiltrated PCF. Moreover, the Ag NPs-doped 6CHBT LC inside both micro-capillaries and PCFs was found to reduce the nematic-isotropic phase transition temperature.

The Turkevich method, in which citrate reduces chloroauric acid, is one of the most popular and standard protocols for the synthesis of gold nanoparticles. Mechanistic studies for this reduction have shown that reducing and capping capabilities of citrate are associated with its structure and particularly with the hydroxyl group attached to the α-position of the carboxyl group. Hence, it should be possible to synthesize gold nanoparticles with similar characteristics upon substitution of citrate by the other α-hydroxycarboxylates. Various α-and β-hydroxycarboxylates have been used to investigate the effect of citrate substitution on reaction outcome. The shape, size distribution, stability and optical properties of gold nanoparticles were characterized by scanning and transmission electron microscopy, differential centrifugal sedimentation and UV–vis spectroscopy. The citrate can be substituted in the Turkevich method by other α-hydroxycarboxylates, however, their structure and the first product of their oxidation strongly influence shape, size and size distribution of synthesized gold nanoparticles. The α-position of the hydroxyl group with respect to the carboxyl group is critical for the reduction to occur. These comprehensive studies provide new insights into the reaction mechanism governing the Turkevich method.

Photonic liquid crystal fibers (PLCFs) have been studied for over a decade as an emerging field of sensing and telecommunication devices. Exciting properties of liquid crystals (LCs) infiltrating photonic crystal fibers (PCFs) can be additionally tuned by doping with various materials that are sensitive to external influences, such as an electric field or temperature. Among them, metallic nanoparticles (NPs) are gathering a great interest, due to their potential applications. NPs can be used to highly influence material properties of LCs as dielectric anisotropy, elastic constants, and viscosity. This may lead to many desirable effects, such as a decrease of the Fredericks threshold voltage or reduction of LC switching times. In this paper we doped a nematic LC with 2-nm gold (Au) and 8-nm silver (Ag) NPs, and infiltrated the prepared mixtures into photonic crystal fibers. We examined the influence of this doping in two different electric field systems, one with two flat copper electrodes, and second with four copper microelectrodes. Our results indicate that metallic NP (both Au and Ag) doping enhances sensitivity of the PLCF-based sensors to an electric field and decreases the threshold voltage. Additionally, due to smaller distances between the electrodes, the proposed four microelectrode system requires lower voltages to effectively tune the PLCF.

Inorganic hollow spheres find a growing number of applications in many fields, including catalysis and solar cells. Hence, a simple fabrication method with a low number of simple steps is desired, which would allow for good control over the structural features and physicochemical properties of titania hollow spheres modified with noble metal nanoparticles. A simple method employing sol–gel coating of nanoparticles with titania followed by controlled silver diffusion was developed and applied for the synthesis of Ag-modified hollow TiO2 spheres. The morphology of the synthesized structures and their chemical composition was investigated using SEM and X-ray photoelectron spectroscopy, respectively. The optical properties of the synthesized structures were characterized using UV–vis spectroscopy. Ag–TiO2 hollow nanostructures with different optical properties were prepared simply by a change of the annealing time in the last fabrication step. The synthesized nanostructures exhibit a broadband optical absorption in the UV–vis range.

We report on a very compact desk-top transmission extreme ultraviolet (EUV) microscope based on a laser-plasma source with a double stream gas-puff target, capable of acquiring magnified images of objects with a spatial (half-pitch) resolution of sub-50 nm. A multilayer ellipsoidal condenser is used to focus and spectrally narrow the radiation from the plasma, producing a quasi-monochromatic EUV radiation (λ = 13.8 nm) illuminating the object, whereas a Fresnel zone plate objective forms the image. Design details, development, characterization and optimization of the EUV source and the microscope are described and discussed. Test object and other samples were imaged to demonstrate superior resolution compared to visible light microscopy.

Noise defines the minimum level of the operational signal and is an important figure of merit for various devices. Here, we studied the low-frequency (1/f) noise characteristics of randomly oriented networks of carbon nanotubes and examined the effect of ultraviolet (UV) light on it. The amplitude of 1/f noise in our devices was strongly affected by the quality of nanotubes. This makes noise spectroscopy an effective tool to characterize the structural quality of carbon nanotube devices. UV illumination increased the device resistance and noise amplitude preserving the spectra shapes. This effect remained for tens of minutes even after the UV light was turned off. We observed a completely different trend of noise spectra and resistance with temperature as compared to UV illumination. These results indicated at least two important components of resistance that contribute to the total resistance of the device and are essential to describe the nanotube networks correctly.

Background The accessibility of the remineralizing ions in teeth's environment is essential for their incorporation into caries-affected dentin. Novel bioglass-reinforced materials capable of releasing fluoride, calcium and phosphates may be particularly useful in the tissue remineralization process. A novel restorative material, ACTIVA BioActive-Restorative (Pulpdent Corp., Watertown, USA), is a hydrophilic resin-modified glassionomer cement (RMGIC) enriched with bioglass particles and fortified with a patented rubberized polymer resin. Its application in restorative dentistry may be significant, promoting remineralization of carious lesions. Objectives The aim of the study was to compare the fluoride ion release profiles from a bioglass-reinforced RMGIC, a conventional glass-ionomer cement (GIC) and a nanohybrid restorative polymer resin. Material and methods The quantity of fluoride ions released from ACTIVA, Ketac Molar Quick Aplicap and Tetric EvoCeram was assessed using a fluoride-specific electrode. The surface characteristics of the preand post-experimental specimens were studied using a scanning electron microscope (SEM) and confocal microscope. An X-ray powder diffraction (XRD) analysis was additionally used to examine the chemical compositions of the dental materials. Results The greatest quantity of fluoride ions was freed from the GIC specimens (20.698-54.118 ppm), followed by the bioglass-reinforced RMGIC (from 1.236 to 15.552 ppm) and nanohybrid polymer resin (0.370-1.148 ppm). The pre-experimental specimens of the bioglass-reinforced RMGIC were porous, while the post-experimental specimens were smoother with visible micro-cracks. The XRD analysis of the bioglass particles confirmed that the material was composed mainly of fluoride (27.70 mass%), silicon (15.62 mass%), aluminum (5.91 mass%), and calcium (5.40 mass%). Conclusions The fluoride ion release profile of ACTIVA was lower than the GIC Keta Molar Quick Aplicap, but significantly higher than the nanohybrid restorative polymer resin Tetric EvoCeram.

Raman spectroscopy has become a standard tool for identification of hazardous materials by first responders. However, despite many advantages of this technique, it has also a limitation, which is low sensitivity. This limitation could be overcome by Surfaced Enhanced Raman Spectroscopy, technique which still waits for real-world applications. In this paper, we present an overview of both methods, Raman and SERS spectroscopies, and examples of their uses for detection and identification of biological, chemical and explosive materials.

The 50 μm thick Ni3Al thin foils were investigated as the solid-state catalyst. In this study, a cyclic Ni3Al catalysts pretreatment process was performed to obtain more uniform carbon nanotubes and gradual fragmentation of Ni nanoparticles. In temperature about 500oC the cyclic methanol decomposition was conducted. The change of hydrogen yield in methanol decomposition over tested catalysts in following cyclic pretreatment was analyzed in details. The carbon nanostructures formed during methanol decomposition was investigated by SEM, BET, XRD and Raman spectroscopy. It has been proven that the Ni nanoparticles agglomerated with following consecutive cycles, caused gradual decrease of methanol conversion and hydrogen yield in every next cycle.

The Turkevich synthesis method of Au nanoparticles (AuNPs) was adopted for direct fabrication of SiO2@Au and TiO2@Au core-shell nanostructures. In this method, chloroauric acid was reduced with trisodium citrate in the presence of amine-functionalized silica or titania submicroparticles. Core-shells obtained in this way were compared to structures fabricated by mixing of Turkevich AuNPs with amine-functionalized silica or titania submicroparticles. It was found that by modification of reaction conditions of the first method, such as temperature and concentration of reagents, control over gold coverage on silicon dioxide particles has been achieved. Described method under certain conditions allows fabrication of semicontinuous gold films on the surface of silicon dioxide particles. To the best of our knowledge, this is the first report describing use of Turkevich method to direct fabrication of TiO2@Au core-shell nanostructures.

In this paper we present the obtained experimental results for enhancing the parameters of photonic crystal fibers infiltrated with a modified 6CHBT doped with gold nanoparticles. By admixing a special liquid crystalline material we were able to widen the working temperature range of our samples. Doping our liquid crystal mixture with nanoparticles visibly enhances the thermal and electro-optical properties of the infiltrated photonic crystal fibers. Additionally, the use of a specially designed four microelectrode system allowed to decrease voltage. Thanks to the introduced modifications we noticed a significant reduction of threshold voltages (up to 44%), rise times (up to 30%) and fall times (up to 50%).

Carbon nanotubes are proposed for reinforcement of the hydroxyapatite coatings to improve their adhesion, resistance to mechanical loads, biocompatibility, bioactivity, corrosion resistance, and antibacterial protection. So far, research has shown that all these properties are highly susceptible to the composition and microstructure of coatings. The present research is aimed at studies of multi-wall carbon nanotubes in three different combinations: multi-wall carbon nanotubes layer, bilayer coating composed of multi-wall carbon nanotubes deposited on nanohydroxyapatite deposit, and hybrid coating comprised of simultaneously deposited nanohydroxyapatite, multi-wall carbon nanotubes, nanosilver, and nanocopper. The electrophoretic deposition method was applied for the fabrication of the coatings. Atomic force microscopy, scanning electron microscopy and X-ray electron diffraction spectroscopy, and measurements of water contact angle were applied to study the chemical and phase composition, roughness, adhesion strength and wettability of the coatings. The results show that the pure multi-wall carbon nanotubes layer possesses the best adhesion strength, mechanical properties, and biocompatibility. Such behavior may be attributed to the applied deposition method, resulting in the high hardness of the coating and high adhesion of carbon nanotubes to the substrate. On the other hand, bilayer coating, and hybrid coating demonstrated insufficient properties, which could be the reason for the presence of soft porous hydroxyapatite and some agglomerates of nanometals in prepared coatings.

In this paper, we present our recent research results on light propagation in photonic crystal fibers (PCFs) infiltrated with a 6CHBT nematic liquid crystal (LC) doped with 2-nm gold nanoparticles (NPs) with a concentration in the range of 0.01 - 0.5% wt. Electro-optical response times and thermal tuning of the investigated samples have been studied in detail. We have observed up to ~80% decrease of rise times for different concentrations of gold NPs in the LC. Moreover, a significant reduction of the Fréedericksz threshold voltage (up to 60%) has been observed for samples with higher concentrations of 2-nm gold NPs in 6CHBT.

In recent years, growing threat of terrorist attacks with use of chemical or biological warfare agents is observed. Biological agents, due to often delayed effects, higher lethality and more difficult detection and identification compared to chemical agents, are especially dangerous. Therefore, rapid detection and discrimination of dangerous biological materials has become a security aim of considerable importance. Various analytical methods, including FTIR spectroscopy combined with statistical analysis have been used to discriminate various bioagents and their background interferents. The applicability for this purpose of another spectroscopic technique, Surface Enhanced Raman Spectroscopy (SERS), has also been intensively investigated in recent years. In this work, the results of the application of FTIR technique performed in reflectance mode using Horizontal Attenuated Total Reflectance accessory (HATR) for discrimination of vegetative bacteria, bacterial spores and background interferents are discussed. Applied technique is shown to be capable of distinguishing between vegetative bacteria, bacterial spores and fungi against other biological specimens. In addition, the results of initial studies on application of plasmonic nanostructures for enhancement of Raman scattering signals of bacterial cells are discussed. Our studies have shown that it is possible to obtain Raman scattering signal from single bacterial cell in presence of single plasmonic nanostructure.

Liquid crystals over the last two decades have been successfully used to infiltrate fiber-optic and photonic structures initially including hollow-core fibers and recently micro-structured photonic crystal fibers (PCFs). As a result photonic liquid crystal fibers (PLCFs) have been created as a new type of micro-structured fibers that benefit from a merge of “passive” PCF host structures with “active” LC guest materials and are responsible for diversity of new and uncommon spectral, propagation, and polarization properties. This combination has simultaneously boosted research activities in both fields of Liquid Crystals Photonics and Fiber Optics by demonstrating that optical fibers can be more “special” than previously thought. Simultaneously, photonic liquid crystal fibers create a new class of fiber-optic devices that utilize unique properties of the photonic crystal fibers and tunable properties of LCs. Compared to „classical” photonic crystal fibers, PLCFs can demonstrate greatly improved control over their optical properties. The paper discusses the latest advances in this field comprising PLCFs that are based on nanoparticles-doped LCs. Doping of LCs with nanoparticles has recently become a common method of improving their optical, magnetic, electrical, and physical properties. Such a combination of nanoparticles-based liquid crystals and photonic crystal fibers can be considered as a next milestone in developing a new class of fiber-based optofluidic systems.

We report on a very compact desk-top transmission extreme ultraviolet (EUV) microscope based on a laser-plasma source with a double stream gas-puff target, capable of acquiring magnified images of objects with a spatial (half-pitch) resolution of sub-50 nm. A multilayer ellipsoidal condenser is used to focus and spectrally narrow the radiation from the plasma, producing a quasi-monochromatic EUV radiation (λ = 13.8 nm) illuminating the object, whereas a Fresnel zone plate objective forms the image. Design details, development, characterization and optimization of the EUV source and the microscope are described and discussed. Test object and other samples were imaged to demonstrate superior resolution compared to visible light microscopy.

In this paper we report studies on the influence of silver island films’ thickness on their optical and surface-enhanced Raman scattering properties. The semicontinuous silver films of thickness in range 3 – 10 nm were fabricated using electron beam physical vapour deposition and their optical properties were characterized using UV-Vis-NIR spectroscopy. The SERS enhancement properties of fabricated films were evaluated using p -mercaptoaniline as an testing analyte. It was found that with increasing thickness of the silver films their plasmon resonance becomes broader and its maximum shifts toward longer wavelengths. The largest SERS signal enhancement was observed for the 7 nm thick Ag films. Keywords : metal island film, semicontinuous metal film, plasmon resonance, surface enhanced Raman scattering. INTRODUCTION Metal island films (MIFs) also called semicontinuous metal films composed of random metal (silver, gold) nanostructures on dielectric substrates are useful in a wide variety of applications exploiting electromagnetic processes. Optical properties of such films can be controlled by adjustment of their morphology [1, 2]. Electromagnetic radiation interacting with MIF’s metallic nanostructures can excite plasmons – collective oscillations of free electrons. This may lead to electromagnetic field enhancement in the vicinity of metallic film. Materials placed in proximity of metal nanostructure experience dramatically enhanced optical responses. This feature is employed in applications such as analysis of chemical and biological substances using spectroscopic methods such as surface enhanced Raman scattering (SERS [3-5]), surface enhanced infrared absorption (SEIRA [6,7]) and also to increase the efficiency of photovoltaic cells [8,9]. Such films may be easily obtained on various substrates by physical vapour deposition techniques [1,2,10] and through chemical reactions [11,12]. In this paper we report studies on the influence of metal island silver films’ thickness on their optical and surface-enhanced Raman scattering properties.

Surface-enhanced Raman spectroscopy (SERS) and self-assembled monolayer (SAM) approaches were used to investigate the reactions of organic monoradicals with methanol. An attempt was made to generate monoradicals from thiophenols and phenylmethanethiols substituted with bromine, iodine, and nitro groups by irradiation with UV light. Monolayers of radical precursors were deposited on SERS substrates, which were then immersed in methanol and irradiated for 1 and/or 3, 6, 12 and 24 h in a UV photochemical reactor. Pre- and postreaction SERS spectra were obtained by using a confocal Raman microscope and compared with the spectra of expected products of the radical reaction with methanol. Our studies have shown that the efficiency of monoradical generation is highly dependent on the chemical structure of the precursor. In addition, it is shown that both the SERS substrate and experimental conditions used strongly influence the obtained results.