Photoacoustic Analysis of Pigments from Archeological Ceramics

Photoacoustic spectroscopy (PAS) is widely used for diverse applications in different areas. These include studies in material, environmental, and life sciences. In the present work the study of pigments from pottery surfaces and volumes of Mexican (Aztec) and Poblana cultures that were developed in central Mexico from 1325 to 1521 and 1521 to 1800, respectively, is reported. The optical absorption spectra from each archeological sample was obtained using PAS. The superficial spectra were also compared with standard color pigments and archeological registers. Complementary energy dispersive spectroscopy (EDS) analysis of these archeological potteries gave us their elemental composition which agreed with other studies about their composition and technology of the pottery manufacturing.     

Synthesis and electrocatalytic activity of platinum nanoparticle/carbon nanotube composites

Pt/CNT nanocomposite materials with an average platinum particle size of 3–5 nm and platinum content of 13–28 wt % have been prepared by reducing chloroplatinic acid, H₂PtCl₆, in the presence of conical carbon nanotubes. The effect of synthesis conditions on the average platinum particle size, total platinum content, and surface composition of the nanocomposites has been studied using X-ray photoelectron spectroscopy, IR spectroscopy, electron microscopy, X-ray diffraction, and thermogravimetry. The materials have been tested as catalysts for hydrogen oxidation and oxygen reduction. Their performance has been assessed by cyclic and steady-state voltammetric techniques. The structure and composition effects on the electrocatalytic properties of the nanocomposites are discussed.     

Effects of thermal annealing on the electrical and structural properties of Pt/Mo Schottky contacts on n-type GaN

Thermal annealing temperature effects on the electrical and structural properties of platinum/molybdenum (Pt/Mo) Schottky contacts on n-type GaN have been investigated by current–voltage (I–V), capacitance–voltage (C–V), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) techniques. As-deposited Pt/Mo/n-GaN Schottky diode exhibits barrier height of 0.75 eV (I–V) and 0.82 eV (C–V). Upon annealing at 400 and 500 °C, the barrier height slightly increased to 0.77 eV (I–V) and 0.92 eV (C–V) and 0.82 eV (I–V) and 0.97 eV (C–V), respectively. A maximum barrier height of 0.83 eV (I–V) and 0.99 eV (C–V) is obtained on the Pt/Mo contacts annealed at 600 °C. X-ray photoelectron spectroscopy results shows that the Ga 2p core-level shift towards the low-energy side for the contact annealed at 600 °C as compared to the as-deposited one. Based on the results of XPS and XRD studies, the formation of gallide phases at Pt/Mo/n-GaN interface could be the reason for the increase of Schottky barrier heights upon annealing at elevated temperatures. The atomic force microscopy (AFM) results showed that the Pt/Mo contact does not seriously suffer from thermal degradation during annealing even at 600 °C (RMS roughness of 5.41 nm). These results make Pt/Mo Schottky contacts attractive for high temperature device applications.     

Creatinine biomaterial thin films grown by laser techniques

Creatinine thin films were synthesised by matrix assisted pulsed laser deposition (PLD) techniques for enzyme-based biosensor applications. An UV KrF* (λ = 248 nm, τ∼10 ns) excimer laser source was used for the irradiation of the targets at incident fluence values in the 0.3–0.5 J/cm² range. For the matrix assisted PLD the targets consisted on a frozen composite obtained by dissolving the biomaterials in distilled water. The surface morphology, chemical composition and structure of the obtained biomaterial thin films were investigated by scanning electron microscopy, Fourier transform infrared spectroscopy, and electron dispersive X-ray spectroscopy as a function of the target preparation procedure and incident laser fluence.     

Synthesis and characterization of anatase and rutile TiO2 nanorods by template-assisted method

Well-aligned anatase and rutile TiO₂ nanorods and nanotubes with a diameter of about 80–130 nm have successfully been fabricated via sol-gel template method. The prepared samples were characterized by using thermogravimetric (TG) and differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDS). The XRD results indicated that the TiO₂ nanorods were crystallized in the anatase and rutile phases, after annealing at 400–800 °C for different periods of time from 0.2 to 10 h.     

Preparation and characterization of nanostructured copper bismuth diselenide thin films from a chemical route

Thin films of copper bismuth diselenide were prepared by chemical bath deposition technique ontoglass substrate below 60°C. The deposition parameters such as time, temperature of deposition and pH of the solution, were optimized. The set of films having different elemental compositions was prepared by varying Cu/Bi ratio from 0·13–1·74. Studies on structure, composition, morphology, optical absorption and electrical conductivity of the films were carried out and discussed. Characterization includes X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray analysis (EDAX), absorption spectroscopy, and electrical conductivity. The results are discussed and interpreted.     

Characterization and photocatalytic activity of TiO2–MxOy (MxOy?=?SiO2, Al2O3, and ZrO2) mixed oxides synthesized by microwave-induced solution combustion technique

Titania–silica, titania–alumina, and titania–zirconia mixed oxides (1:1 molar ratio) were prepared by a microwave-induced solution combustion synthesis technique. The prepared materials were characterized by thermogravimetry/differential thermal analysis, X-ray diffraction (XRD), Raman spectroscopy, BET surface area, X-ray photoelectron spectroscopy (XPS), ultraviolet–visible diffuse reflectance spectroscopic (UV–Vis DRS), and Fourier transform infrared (FTIR) techniques to assess their physicochemical properties. Their photocatalytic activity for the degradation of phenol in aqueous solution under sunlight was studied. XRD and Raman studies revealed the presence of titania in the form of anatase phase in all the mixed oxides synthesized. The XRD studies further suggested that titania–zirconia contains an additional (Ti,Zr)O₂ phase. UV–Vis DRS results reveal that all samples exhibit absorption maxima near visible region. FTIR results revealed the presence of Ti–O–Si linkages in the titania–silica sample, which are responsible for its higher activity in the photocatalytic degradation of phenol under sunlight.     

Grafting of gold nanoparticles and nanorods on plasma-treated polymers by thiols

Grafting of gold nanoparticles and nanorods on the surface of polymers, modified by plasma discharge, is studied with the aim to create structures with potential applications in electronics or tissue engineering. Surfaces of polyethyleneterephthalate and polytetrafluoroethylene were modified by plasma discharge and subsequently, grafted with 2-mercaptoethanol, 4,4′-biphenyldithiol, and cysteamine. The thiols are expected to be fixed via one of –OH, –SH or –NH₂ groups to reactive places on the polymer surface created by the plasma treatment. “Free” –SH groups are allowed to interact (graft) with gold nanoparticles and nanorods. Gold nano-objects were characterized before grafting by transmission electron microscopy and UV–Vis spectroscopy. X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and electrokinetic analysis (zeta potential determination) were used for the characterization of polymer surface at different modification phases. It was proved by FTIR and XPS measurements that the thiols were chemically bonded on the surface of the plasma-treated polymers, and they mediate subsequent grafting of the gold nano-objects. On the surfaces, modified polymers were indicated some objects by AFM, size of which was dramatically larger in comparison with that of original nanoparticles and nanorods. This result and the other results of UV–Vis spectroscopy indicate an aggregation of deposited gold nano-objects.     

Effect of Pb (Yb1/2Nb1/2)O3 on phase transition and thermal and electrical properties of PZ–PYbN solid solution on PZ-rich side

The (1 − x)PbZrO₃–xPb(Yb_1/2Nb_1/2)O₃ (PZ–PYbN) ceramics, with the compositions, x = 0.00–0.50, were prepared by the wolframite precursor method. The crystal structure and electrical and thermal properties of PbZrO₃ ceramic were investigated as a function of the composition, x, using X-ray diffraction, dielectric spectroscopy, hysteresis measurement and differential scanning calorimetry techniques. The results indicated that the solid solution, PZ–PYbN, changed from orthorhombic to rhombohedral symmetry when the amount of PYbN increased. The pyrochlore phase identified as Yb/Nb mixed compound was observed at the composition, x ≥ 0.2. For the compositions, x = 0.00–0.10, ceramics showed a sharp phase transition from AFE to PE. Furthermore, the intermediate FE phase was absent from the PZ–PYbN system.     

Hierarchical meso–macroporous titania-supported CuO nanocatalysts: preparation,characterization and catalytic CO oxidation

Hierarchically mesoporous–macroporous titanium dioxide (MMTD) was synthesized by the hydrolysis of tetrabutyl titanate in the absence of surfactant and autoclaving at 60 °C, which exhibits a porous hierarchy of wormhole-like mesostructure in the framework of macrochannels. Different contents of CuO nanoparticles were supported on the MMTD by a deposition–precipitation (DP) method, retaining the high surface areas and hierarchical porosity. The prepared MMTD support and the resulting CuO/MMTD nanocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N₂ adsorption analysis, temperature-programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS) techniques. Their catalytic behavior for low-temperature CO oxidation was studied by using a microreactor–GC system, and the CuO/MMTD catalyst with 8 wt% CuO content and calcined at 400 °C was found to have the highest catalytic activity. The catalytic activity depended on the CuO loading amount, the precalcination temperature, the meso–macroporous framework, the surface area, and the particle size of the CuO/MMTD catalysts.     

Poly(ε-caprolactone)/nano fluoridated hydroxyapatite scaffolds for bone tissue engineering: in vitro degradation and biocompatibility study

In this study, biodegradation and biocompatibility of novel poly(ε-caparolactone)/nano fluoridated hydroxyapatite (PCL–FHA) scaffolds were investigated. The FHA nanopowders were prepared via mechanical alloying method and had a chemical composition of Ca₁₀ (PO₄)₆OH_2–x F _x (where x values were selected equal to 0.5 and 2.0). In order to fabricate PCL–FHA scaffolds, 10, 20, 30 and 40 wt% of the FHA were added to the PCL. The PCL–FHA scaffolds were produced by the solvent casting/particulate leaching using sodium chloride particles (with diameters of 300–500 μm) as the porogen. The phase structure, microstructure and morphology of the scaffolds were evaluated using X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy techniques. Porosity of the scaffolds was measured using the Archimedes’ Principle. In vitro degradation of PCL–FHA scaffolds was studied by incubating the samples in phosphate buffered saline at 37°C and pH 7.4 for 30 days. Moreover, biocompatibility was evaluated by MTT assay after seeding and culture of osteoblast-like cells on the scaffolds. Results showed that the osteoblast-like cells attached to and proliferated on PCL–FHA and increasing the porosity of the scaffolds increased the cell viability. Also, degradation rate of scaffolds were increased with increasing the fluorine content in scaffolds composition.     

Chemical deposition of silver shells on the surface of hollow glass microspheres

This article reports the chemical deposition of silver shells on the surface of hollow glass microspheres. This was accomplished by using titanium dioxide, derived from titanium (IV) tetra-n-butoxide, as the surface modifier. Two routes of formation of thin titanium dioxide layers on the substrate were compared in terms of composition and properties: photochemical approach and atmospheric hydrolysis. The structure and composition of the samples were characterized by atomic force microscopy, scanning electron microscopy, IR spectroscopy, electron paramagnetic resonance spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The resulting thickness of uniform silver shells on the surface of microspheres averaged out at 1.0–1.25 μm.     

Synthesis and characterization of CuInS<Subscript>2</Subscript> thin film structures

CuInS₂ is a promising semiconductor material for solar cell applications. Here we use a mild solvothermal synthesis route to prepare CuInS₂ films with different thicknesses and morphologies on fluorine-doped tin oxide coated glass. The microstructure of the films is studied in detail by scanning electron microscopy and transmission electron microscopy (TEM) and associated analytical techniques. For further characterization, we apply X-ray diffraction and UV/Vis absorption spectroscopy. Two different films are synthesized using different reagent stoichiometries and thermal treatments. The thicker film (25 μm) consists of three different regions. Close to the substrate a 600 nm thick densely packed layer occurs, on which a 1 μm thick flaky structure is found. On top of this structure, microspheres are located which possess a size of about 3 μm and are composed of numerous flakes. The thinner film consists of a 200 nm thick densely packed layer and a net-like structure built of individual flakes as well. In both films, TEM reveals that the flakes are adjacent to 10 nm thin branch-like rods. Energy dispersive X-ray spectroscopy of the densely packed layers indicates a Cu-rich composition which suggests them to be a p-type semiconductor. The rods and the flakes show a stoichiometric composition. Due to its high surface area, the thinner film offers a promising morphology for solar cell applications based on the large available area for the separation of electron–hole pairs, when the material is combined with a suitable electron conductor.     

Synthesis and characterizations of novel acid functionalized and fluorescent poly(ε-caprolactone)

ε-Caprolactone (CL) was subjected to ring opening polymerization (ROP) under inert (nitrogen) atmosphere at 413 K for 1 h in the presence of stannous octoate (SO) as a catalyst and Eosin Y, a xanthenes type dye as a novel chemical initiator. The ROP was carried out at two different experimental conditions, namely at various concentrations of initiator and monomer, to get more scientific information from the resultant product. Thus, obtained Eosin Y conjugated poly(ε-caprolactone) (PCL) was characterized by different analytical tools like FTIR spectroscopy, NMR spectroscopy, gel permeation chromatography (GPC), UV–Visible spectroscopy, photoluminescence (PL) spectroscopy, X-ray photoelectron spectroscopy (XPS), and differential scanning calorimetry (DSC). Finally, the morphology of the Eosin Y conjugated PCL was studied by scanning electron microscopy (SEM). The binding constant (K) was determined from both UV–Visible spectroscopy and PL spectroscopy, and the static quenching mechanism was proposed. The number of binding site (n) was also determined from PL spectroscopy and the results were compared with the FTIR-RI method.     

Electrocatalytic behavior of Ni-based amorphous alloys for hydrogen evolution

Ni-based amorphous alloys were synthesized by rapid quenching from the melt, using a planar flow technique. Their amorphous nature and thermal stability were studied by X-ray diffraction and differential scanning calorimetry. The electrocatalytic activity of the as-quenched amorphous alloys with respect to the hydrogen evolution reaction (HER) in alkaline water electrolysis was studied in relation to the alloy composition. The kinetic parameters of the HER were evaluated by cyclic voltammetry and impedance spectroscopy techniques in 6 M KOH at room temperature. The electrocatalytic activity of the amorphous alloys was found to depend on the alloy composition. It was obtained that molybdenum containing amorphous alloys (Ni–Mo–B) showed a superior electrocatalytic activity in the HER compared to Ni–(Nb,Ta)–B and Ni–Si–B, as Ni_66.5Mo_28.5B₅ revealed considerably lower charge transfer resistance and higher exchange current density than Ni₆₃Mo₂₇B₁₀. The results have to be attributed to an improved intrinsic activity of the Ni–Mo–B alloys compared to the other Ni-based glasses.     

Use of analytical techniques for identification of inorganic polymer gel composition

In the present experimental study, a number of analytical techniques were used to identify the composition of gel and thus elucidate to a certain extent the mechanisms involved during synthesis of inorganic polymers. The raw materials used, low calcium slag from a ferronickel plant and commercial glass, were alkali activated by Na₂SiO₃ and KOH solutions. X-ray diffraction (XRD) is used to identify new formed phases; deconvolution of the amorphous peaks in X-ray powder diffraction patterns enables the quantitative estimation of the amorphous phases present. The morphology and composition of the inorganic polymer gel may be defined by optical reflection microscopy (ORM) and scanning electron microscopy (SEM). Fourier transform infrared spectroscopy (FTIR) is a useful tool for the identification of specific molecular structures including Si–O–Si and Al–O bonds, which define the degree of polysialation. Thermogravimetric analysis (TG) determines water evaporation rates in inorganic polymer structures by recording the weight loss under controlled heating. Finally, the effect of the presence in the starting mixture of heavy metals such as Pb or Cu and anions such as NO₃ ⁻ or SO₄ ²⁻ on the quality of the gel formed and subsequently on the compressive strength of inorganic polymers are studied and discussed.     

Facile preparation of Ag/ZnO nanoparticles via photoreduction

Ag/ZnO nanoparticles can be obtained via photocatalytic reduction of silver nitrate at ZnO nanorods when a solution of AgNO₃ and nanorods ZnO suspended in ethyleneglycol is exposed to daylight. The mean size of the deposited sphere like Ag particles is about 5 nm. However, some of the particles can be as large as 20 nm. The ZnO nanorods were pre-prepared by basic precipitation from zinc acetate di-hydrate in the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide. They are about 50–300 nm in length and 10–50 nm in width. Transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDS), X-ray powder diffraction (XRD), UV–Vis spectroscopy, X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) were used to characterize the resulting Ag/ZnO nanocomposites.     

Effect of humidity treatment on the structure and photocatalytic properties of titania mesoporous powder

In the work presented here, mesoporous titania (MT) powders is synthesized by sol–gel method using amphiphilic triblock copolymer as a template at two different levels of relative humidity (RH); 20 and 80%. Various techniques such as small angle X-ray diffraction (SAXRD), wide angle X-ray diffraction (XRD), UV–visible spectroscopy, high resolution transmission electron microscopy (HRTEM), Fourier transformed infra red (FTIR) spectroscopy and N₂-adsorption/desorption analysis were utilized to study the prepared samples. Further, the photocatalytic activities of the prepared samples were evaluated from the photo-degradation analysis of methylene blue (MB). For the sample treated with 80%RH the formation of an ordered mesoporous structure with a high specific surface area (172 m²g⁻¹), mesoporosity (48%) and enhanced photocatalytic activity were obtained compared to those of the sample subjected to 20%RH. The observed increased MB degradation for the latter is mainly attributed to the formation of higher specific surface area and mesoporosity. The availability of highly ordered open pore channels could provide increased contacts between reactants in the solution and the active sites on the surfaces of MT particles.     

Preliminary results of simultaneous radon and thoron tests in Ottawa

Ottawa is the capital city of Canada. In the previous crossCanada radon survey, Ottawa was not included. There is greatinterest to know radon level as well as thoron concentrationin Ottawa homes. Therefore, radon/thoron discrimination detectorsdeveloped at the National Institute of Radiological Sciencesin Japan were deployed in 93 houses for a period of 3 months.As expected, thoron is present in Ottawa homes. Radon concentrationsranged from 8 to 1525 Bq m^–3 while thoron concentrationsvaried from 5 to 924 Bq m^–3. The arithmetic mean of radonand thoron concentrations were found to be 110 ± 168and 56 ± 123 Bq m^–3, respectively.     

Fabrication of nanocomposites based on carbon nanotubes containing Pt nanoparticles and TiO<Subscript>2</Subscript>

Using conical multiwalled carbon nanotubes (CNTs), we have prepared Pt/CNT and Pt/TiO₂/CNT nanocomposites with an average platinum particle size of 3–5 nm, Pt/Ti molar ratio on the surface in the range 3.5–4, and C/Pt = 21–22. Titania was deposited onto the CNTs through titanium tetrachloride (TiCl₄) hydrolysis. Platinum particles were produced by reducing chloroplatinic acid (H₂PtCl₆) with sodium borohydride (NaBH₄) in the presence of CNTs. The composition and structure of the composites have been studied using X-ray photoelectron spectroscopy, electron microscopy, X-ray diffraction, and thermogravimetry. The materials have been tested as catalysts for hydrogen oxidation and oxygen reduction. The results demonstrate that the modification of Pt/CNT with titania enhances the catalytic activity of the material.