The aim of this study was to investigate the structural, thermal, optical and biocompatibility properties of poly(acrylic acid)(PAA)/organo-modified nanohydroxyapatite (OM-nHAp) nanocomposites synthesized by solvent intercalation method. The characterization of PAA/OM-nHAp nanocomposites was made by different techniques. SEM and TEM results showed that OM-nHAp particles were dispersed in the nanoscale into PAA matrix and that they were uniformly distributed within film. Glass transition temperature of PAA increased with OM-nHAp content. Ultraviolet (UV) absorbance experiments showed that PAA had a higher UV transmission than its nanocomposites. The biocompatibility of nanocomposites was also examined in simulated body fluid.
Nasar Ahmed, Abdul Majid, M.A. Khan, M. Rashid, Z.A. Umar and M.A. Baig
Self-assembled Zn/ZnO microspheres have been accomplished on selected sites of boron doped P-type silicon substrates using hydrothermal approach. The high density Zn/ZnO microspheres were grown on the Si substrates by chemical treatment in mixed solution of zinc sulfate ZnSO4·7H2O and ammonium hydroxide NH4(OH) after uniform heating at 95 °C for 15 min. The Zn/ZnO microspheres had dimensions in the range of 1 μm to 20 μm and were created only on selected sites of silicon substrate. The crystal structure, chemical composition and morphology of as-prepared samples were studied by using scanning electron microscope SEM, X-ray diffraction XRD, energy dispersive X-ray spectroscopy EDS, Fourier transform infrared spectroscopy FT-IR and UV-Vis diffuse reflectance absorption spectra DRS. The energy band gap Eg of about 3.28 eV was obtained using Tauc plot. In summary, this study suggests that interfacial chemistry is responsible for the crystal growth on indented sites of silicon substrate and the hydrothermal based growth mechanism is proposed as a useful methodology for the formation of highly crystalline three dimensional (3-D) Zn/ZnO microspheres.
A novel and low-cost synthesis of tungsten disulfide (WS2) transition metal dichalcogenide was carried out via gas-solid reaction in a horizontal quartz reactor. In this process, the prepared hollow WO3 precursor was sulfided with CS2 at 550 °C at different durations under N2 gas atmosphere. The as-prepared WS2 samples were formed by substitution of O by S during the sulfidation process. The characterization of these samples was performed employing X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX), Brunauer-Emmett-Teller (BET) specific surface area, X-ray photoelectron spectroscopy (XPS) and UV-Vis absorption spectroscopy. The characterization results showed that the as-prepared WS2 samples were of high quality and purity. No significant differences were observed in various WS2 samples synthesized during different sulfidation periods. The calculated results obtained from the density functional theory (DFT) indicate that WS2 has an indirect band gap of ca. 1.56 eV, which is in agreement with experimental band gap of ca. 1.50 eV. Combining the experimental and DFT results suggests that the novel method used in the synthesis of WS2 has a potential application for large scale production. The obtained WS2 are of high quality and can be implemented in photocatalysis, catalysis, photovoltaics, optoelectronic devices and photosensor devices.
In this study, we present a systematic study of linear and nonlinear optical properties of Para Red with the aim of Z-scan technique and quantum mechanical calculations. The Z-scan experiments were performed using a 532 nm Nd: YAG (SHG) CW laser beam. Para Red exhibited a strong nonlinear refractive index, nonlinear absorption coefficient and third-order nonlinear susceptibility 3.487 × 10−6 cm2/W, 2.341 × 10−1cm/W and 2.157 × 10−4 esu, respectively. Also, quantum chemical analysis was used for the calculation of the dipole moment μ, dipole polarizability α, anisotropy of polarizability Δα and molecular hyperpolarizabilities (β,γ). The results revealed that Para Red has large first and second hyperpolarizabilities. However, from the obtained results, it was found that Para Red can be a promising material for applications in the development of non-linear optical materials.
Organic/inorganic hybrid materials consisting of quantum dots and conjugate polymers are important for the application in light emitting devices. In the present work, we have studied the effect of CdS and CdS/ZnO nanoparticle addition on the structure and fluorescence properties of spin coated PVK (poly(N-vinyl carbozole)) nanocomposite films. CdS nanoparticles were synthesized by simple co-precipitation technique and ZnO shell was grown on the CdS nanoparticles by simple wet chemical approach. The nanoparticles and the hybrid nanocomposites have been characterized by using XRD, SEM, FT-IR, optical absorption and fluorescence spectroscopic techniques. The absorption peak for pure PVK remains at 345.5 nm accompanied with minor hump ~480 nm resulting from the incorporation of nanoparticles. It has been observed that the addition of nanoparticles to the hybrid material results in the enhancement of fluorescence intensity at 410 nm to 450 nm spectral regions. These results are important for the development of new light emitting devices at low fabrication costs.
ZnO-CuO flower-like hetero-nanostructures were successfully prepared by combining hydrothermal and dip coating methods. Flower-like hetero-nanostructures of ZnO-CuO were examined by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and UV-Vis. The sensing properties of ZnO-CuO flower-like hetero-nanostructures to volatile organic compounds (VOCs) were evaluated in a chamber containing acetone or isopropanol gas at room temperature. The sensitivity of ZnO-CuO flower-like hetero-nanostructures to VOCs was enhanced compared to that of pure leafage-like ZnO nanostructures. Response and recovery times were about 5 s and 6 s to 50 ppm acetone, and 10 s and 8 s to 50 ppm isopropanol, respectively. The sensing performance of ZnO-CuO flower-like hetero-nanostructures was attributed to the addition of CuO that led to formation of p-n junctions at the interface between the CuO and ZnO. In addition, the sensing mechanism was briefly discussed.
J. Tomków, D. Fydrych, G. Rogalski and J. Łabanowski
Wet welding is the most common method of welding in water environment. It is most often used for repairing of underwater parts of offshore structures. However, the water as a welding environment causes an increase of susceptibility of steels to cold cracking. For underwater constructions high strength low alloy (HSLA) steel are widely used. In wet welding condition a HSLA steel is characterized by high susceptibility to cold cracking. Temper Bead Welding (TBW) was chosen as a method to improve the weldability of S460N steel. The studies showed that TBW technique causes significant decrease of maximum hardness of heat affected zone (HAZ). The largest decrease in hardness occurred in specimens with the pitches in range 66-100%.
A. Walczak, A. Niewczas, D. Pieniak, L. Gil, E. Kozłowski and P. Kordos
This paper reports the results of compressive strength and elasticity studies of light-cured polymer matrix ceramic composites (LC PMCCs). The main purpose was to obtain new data on experimental composites and compare them with commercial composites from the world’s leading manufacturer. The objective was to investigate the relationship between the content of reinforcing components in the composites studied and the stability of their strength in time, expressed as the number of fatigue thermal cycles.
Thermal barrier coatings (TBC) is one of the most intensively studied of coatings’ applications area. From 1970’s TBC are developed in two independent ways: (i) development in new materials, with lower thermal conductivity, better erosion resistance and better thermal shock resistance or (ii) development in new deposition techniques. On this field besides conventional atmospheric plasma spraying (APS) and almost conventional (because of very common use) EB-PVD method, in the past 20 years two new techniques have been developed, namely suspension plasma spraying (SPS) and solution precursor plasma spraying (SPPS). In this paper only SPS method was described, as well as, new materials, which could be used in industrial applications of TBC. Moreover, the key issues, like suspension preparation, type of suspension injection, interaction between liquid droplets and plasma jet and deposition mechanism were described.
Andrzej Sikora, Magdalena Moczała and Bartosz Boharewicz
In this paper, we present a novel approach developed in order to increase the reliability and accuracy of AFM investigation of morphological changes in a nanocomposite due to exposure to the media causing its degradation. By precise sample positioning and repetitive determination of the roughness changes at specific spots, we were able to create space-related degradation profiles. As the multi-step experiment based on exposure/scanning cycle was performed, we were able to observe a unique response of investigated samples revealing spatial inhomogeneity of the material. In order to present the measurement methodology, we used polystyrene samples containing various quantities of PC61BM nanofiller (0 %, 5 %, 10 % and 20 % of mass proportion), which was exposed to 370 nm UV radiation. Obtained data can be recognized as specific fingerprints of investigated materials. The solution based on creation and analysis of degradation profiles can be particularly useful for diagnostics of nanomaterials and nanocomposites to test their resistance to various conditions.