Changes in pigment profile and surface colour of fig (Ficus carica L.) during drying

In this study, anthocyanins in three fresh fig varieties (Ficus carica L.) cultivated in Turkey were characterised and quantified by HPLC/DAD and HPLC/MS. In addition, the carotenoid composition of Sar?lop and Sar?zeybek, yellow fig varieties, was determined, and then the ripening‐ and drying‐related changes in carotenoids and surface colour of figs were monitored during conventional sun‐drying. Four different anthocyanins, cyanidin‐3‐glucoside, cyanidin‐3,5‐diglucoside, cyanidin‐3‐rutinoside (major anthocyanin) and pelargonidin‐3‐glucoside, were identified in samples. Lutein, zeaxanthin, β‐cryptoxanthin and β‐carotene were carotenoids in yellow fig varieties. Approximately 80% of carotenoid compounds in yellow fig varieties degraded at the end of drying (i.e. seventh day). L (lightness), a (redness and greenness) and b (yellowness and blueness) colour parameters were measured by Hunter Lab system. Great changes in carotenoid composition and surface colour were observed at ripening stage on tree. A significant reduction in L and b values that refers to browning in figs was made in the first 3 days of drying process.     

Potentials of the “Direct inkjet printing” method for manufacturing 3Y-TZP based dental restorations

The potentials of the direct inkjet printing (DIP) method for manufacturing 3Y-TZP dental restorations were investigated. Aqueous inks of 3Y-TZP and carbon were developed and characterised for the DIP method. A sample 3Y-TZP framework of a dental bridge was produced by DIP. The stress distribution on this framework under realistic clenching conditions was simulated using finite element analysis. Four-point bending specimens produced by DIP and a slip cast reference sample were tested to characterise the flexural strength of the DIP produced components.     

CuO as a sintering additive for (Bi1/2Na1/2)TiO3-BaTiO3-(K0.5Na0.5)NbO3 lead-free piezoceramics

CuO as a sintering additive was utilized to explore a low-temperature sintering of 0.92(Bi_1/2Na_1/2)TiO₃-0.06BaTiO₃-0.02(K_0.5Na_0.5)NbO₃ lead-free piezoceramic which has shown a promise for actuator applications due to its large strain. The sintering temperature guaranteeing the relative density of greater than 98% is drastically decreased with CuO addition, and saturates at a temperature as low as ∼930 °C when the addition level exceeds ca. 1 mol.%. Two distinguished features induced by the addition of CuO were noted. Firstly, the initially existing two-phase mixture gradually evolves into a rhombohedral single phase with an extremely small non-cubic distortion. Secondly, a liquid phase induced by the addition of CuO causes an abnormal grain growth, which can be attributed to the grain boundary reentrant edge mechanism. Based on these two observations, it is concluded that the added CuO not only forms a liquid phase but also diffuses into the lattice. In the meantime, temperature dependent permittivity measurements both on unpoled and poled samples suggest that the phase stability of the system is greatly influenced by the addition of CuO. Polarization and strain hysteresis measurements relate the changes in the phase stability closely to the stabilization of ferroelectric order, as exemplified by a significant increase in both the remanent strain and polarization values. Electron paramagnetic resonance (EPR) spectroscopic analysis revealed that the stabilization of ferroelectric order originates from a significant amount of Cu²⁺ diffusing into the lattice on B-site. There, it acts as an acceptor and forms a defect dipole in association with a charge balancing oxygen vacancy.     

Automatic segmentation of human facial tissue by MRI–CT fusion: A feasibility study

The aim of this study was to develop automatic image segmentation methods to segment human facial tissue which contains very thin anatomic structures. The segmentation output can be used to construct a more realistic human face model for a variety of purposes like surgery planning, patient specific prosthesis design and facial expression simulation. Segmentation methods developed were based on Bayesian and Level Set frameworks, which were applied on three image types: magnetic resonance imaging (MRI), computerized tomography (CT) and fusion, in which case information from both modalities were utilized maximally for every tissue type. The results on human data indicated that fusion, thickness adaptive and postprocessing options provided the best muscle/fat segmentation scores in both Level Set and Bayesian methods. When the best Level Set and Bayesian methods were compared, scores of the latter were better. Number of algorithm parameters (to be trained) and computer run time measured were also in favour of the Bayesian method.     

Microstructural development of interface layers between co-sintered alumina and spinel compacts

Tests were performed to investigate the microstructure of the interface between alumina and spinel materials after high temperature thermal treatment (1500 °C). The first test involved co-sintering of co-pressed alumina and spinel compacts. Microstructures were investigated by SEM, EDS, WDS and EBSD. A microstructurally distinct layer with columnar grains of up to 40 μm length and 5 μm width was observed after 16 h at 1500 °C. Growth rate of the columnar spinel grains from parent spinel towards alumina follows parabolic kinetics, controlled by a mixed process of O²⁻ ion diffusion and interface reaction. Diffusion couples of spinel and alumina were investigated. Same columnar spinel grains were observed at the interface which grew into alumina during thermal treatment with the same kinetics as in co-sintering experiments. The shape of the phase boundaries between spinel and alumina can be a further indication of the direction of their growth.     

Mechanical characterisation of miniaturised direct inkjet printed 3Y-TZP specimens for microelectronic applications

Direct inkjet printing (DIP) allows the production of small ceramic specimens with special geometries starting from high solids content suspensions. In this work, thin (300 μm thickness) 3Y-TZP specimens were produced with the DIP technique as model materials for microelectronic applications. The mechanical strength of the printed specimens was evaluated under biaxial loading, and the results were interpreted within the framework of the Weibull theory. Hot-pressed 3Y-TZP specimens with the same geometry and dimensions were tested for comparison. The fracture surfaces were subsequently examined using scanning electron microscopy (SEM). The inkjet printed materials revealed high mechanical reliability (m ≈ 10 for σ₀ ≈ 1400 MPa), which was ascribed to the uniform and defect free microstructure generated by the DIP technique.     

Essential oil composition and antibacterial activity of the grapefruit (Citrus Paradisi. L) peel essential oils obtained by solvent‐free microwave extraction: comparison with hydrodistillation

The chemical composition of the essential oil (EO) obtained by solvent‐free microwave extraction (SFME) and hydrodistillation (HD) from the peel of grapefruit (Citrus Paradisi. L) was analysed by gas chromatography/mass spectrometry (GC/MS). Totally, twenty‐five components were identified in the EO. Limonene was observed as dominant (91.5–88.6%) for two extraction methods, SFME and HD, respectively. β‐Pinene (0.8–1.2%), linalool (1.1–0.7%), α‐terpinene (0.7–1.0%) and the other minor components were also detected. Disc diffusion method was applied to determine the antibacterial properties of the EO. The results showed that the EO of grapefruit peel had a wide spectrum of antimicrobial activities against Staphylococcus aureus, Enterococcus faecalis, Staphylococcus epidermidis, Escherichia coli, Salmonella typhimurium, Serratia marcescens and Proteus vulgaris, with their inhibition zones ranging from 11 to 53 mm.     

Magnetic Characterizations of Cobalt Oxide Nanoparticles

Cobalt oxide (Co₃O₄) nanoparticles were synthesized by a novel microwave-assisted decomposition reaction of the cobalt nitrate hexahydrate, Co(NO₃)₂?6H₂O. While most of the traditional methods for the preparation of Co₃O₄ are at relatively high temperature, microwave-assisted decomposition was adapted to have better control in the production of Co₃O₄ nanoparticles. The temperature dependence of the magnetic properties for the Co₃O₄ was investigated by vibrating sample magnetometer (VSM) and electron spin resonance (ESR) techniques. VSM and ESR measurements have shown a phase transition occurring at around 31?K, as the antiferromagnetic transition temperature for the bulk Co₃O₄ crystal exhibits almost the same value. The average particle size of the sample at around the transition temperature is estimated as 2.015?nm. The title compound was characterized and identified by an x-ray powder diffraction (XRD).     

A new route for the synthesis of CuIn0.5Ga0.5Se2 powder for solar cell applications

In this paper, a new and simple method is described that does not use an autoclave to synthesize copper indium gallium diselenide (CuIn_0.5Ga_0.5Se₂) particles from the constituent elements. The process also does not require a post-synthesis selenization step. A solvo-thermal route is followed in which the constituent element powders are dissolved and made to react in a solvent such as ethylenediamine (ED), or triethylenetetramine (TETA). Crystal structure, morphology, composition, and particle size distribution of prepared particles were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), and dynamic light scattering (DLS), respectively. The band gap energies of the prepared particles were determined using an UV-VIS-NIR spectrophotometer. The results indicate that the solvent temperature and the synthesis time significantly affect the formation of single-phase CuIn_0.5Ga_0.5Se₂ and the crystallinity of the particles. Further, the measured band gap energy for the prepared particles is close to that of the bulk material. For example, the single-phase plate-like CuIn_0.5Ga_0.5Se₂ particles with an average particle size of 413.9 nm which can be successfully synthesized at a temperature of 250 °C in 15 h, have a band gap energy of 1.15 eV.