Characterization and mechanical properties of TiO2 nanotubes formed on titanium by anodic oxidation

The well-ordered titanium dioxide (TiO₂) nanotube array surfaces were formed at different voltages such as 20 V, 40 V, 60 V, 80 V and 100 V for 1 h on cp-Ti by anodic oxidation (AO) technique. And then, to improve crystallinity of the surface, heat treatment was applied at 450 °C for 1 h to all surfaces without any morphological changing. The surface and cross sectional morphology, elemental structure, phase composition, functional groups, roughness and thickness, wettability and mechanical results were investigated by SEM, EDX, XRD, FT-IR, AFM, contact angle measurement device and nanoindentation tester, respectively. Mainly, anatase- and rutile-TiO₂ phases were obtained at post-heat treatment whereas only, Ti phase was detected on AO surfaces at pre-heat treatment. All nanotube structures and the elements of Ti and O were uniformly distributed through the whole surface. The roughness and thickness of tube structures usually increased with increasing voltage values and measured. The roughness and thickness values were measured as 10.67–111.97 nm and 0.21–1.92 μm, respectively. TiO₂ nanotube surfaces exhibited hydrophobic behaviors with respect to plain Ti surface. Furthermore, mechanical properties such as hardness and elastic modulus of the coating produced at minimum voltage were great compared to ones at higher voltage and plain Ti surface under a Berkovich indenter due to phase structure, homogeneity and density of nanotube structures.     

PolyHIPE/pullulan composites derived from glycidyl methacrylate and 1,3‐butanediol dimethacrylate‐based high internal phase emulsions

Highly porous composites of poly(glycidyl methacrylate‐co‐1,3‐butanediol dimethacrylate) and pullulan were prepared as semi‐interpenetrating polymer networks by cross‐linking of high internal phase emulsions (HIPEs). HIPEs were prepared by using an aqueous phase made of pullulan dissolved in deionised water. Instead of conventional cross‐linkers such as divinyl benzene, 1,3‐butanediol dimethacrylate was used as a flexible co‐monomer. Morphological and mechanical properties of the porous composites with an initial pullulan loading ranging from 1 to 10 wt % have been investigated. Resulting composites were tested in terms of uniaxial compression stress and it was found out that the use of pullulan and flexible co‐monomer in the HIPE preparation increases the compression modulus from 13.53 to 30.8 MPa. Textural analyses of the resulting composites show that in all cases open cellular foams composed of primary cavities (～112–74 μm) connected with secondary interconnected pores were produced with a specific surface area in the range of 1.7–3.0 m² g^?1. In addition, the influence of using porogen in the oil phase was investigated. It was found that using a porogen reduces the cavity size diameter from ～112 to 20 µm and increases the compression modulus from 13.53 to 47.06 MPa. POLYM. ENG. SCI., 55:2636–2642, 2015. © 2015 Society of Plastics Engineers     

Preparation of low cost activated carbons from various biomasses with microwave energy

Activated carbons are generated from various waste biomass sources such as waste tea, almond shells, tomato stems and leaves. Porous materials were prepared with phosphoric acids activation by microwave energy in a covered Teflon reactor for 1, 2, 3, and 4?min. The activated carbons were characterised in terms of surface area, pore size distribution, pore volume, FTIR analysis. The highest surface areas were obtained using almond shells (1,002?m²/g), waste tea (702?m²/g), tomato stems (813?m²/g) and tomato leaves (117?m²/g), respectively. The type of the raw material has significant effects on the characteristics of the final product. It was shown that porous carbons with high surface area could be prepared by short microwave radiation periods such as 2?C3?min.     

Zeta potential study of natural‐ and acid‐activated sepiolites in electrolyte solutions

Detailed characterisation of natural sepiolite from the Eskisehir region of Turkey was performed using X‐ray diffraction, X‐ray fluorescence, field emission scanning electron microscopy, specific surface area (BET method), Fourier transform infrared spectra, derivative thermogravimetry (DTG) and differential thermal analysis. Electrokinetic properties of natural‐ and acid‐activated sepiolites were investigated as a function of the concentration of various electrolytes, such as NaCl, KCl, LiCl, CaCl₂, MgCl₂, NaNO₃, Na₂CO₃, FeCl₃ and Al(NO₃)₃. While mono and divalent cations and anions did not change the surface charge of natural‐ and acid‐activated sepiolite, trivalent cations changed the surface charge from negative to positive. Acid‐activated sepiolite samples shifted towards the positive region in nearly all electrolyte solutions when compared with the natural sepiolite. © 2011 Canadian Society for Chemical Engineering     

The visualization of hepatic vasculature by X-ray micro-computed tomography

In this study, X-ray micro-computed tomography (CT) was used to reconstruct the fine structure macro- and microvasculature in three dimensions in contrast-enhanced rat liver samples. The subsequent application in the experimental CC531s colorectal cancer model was concurrent with results obtained from confocal microscopy in earlier studies. The en bloc stains osmium tetroxide in combination with uranyl acetate provided an excellent contrasting result for hepatic tissue after a trial of several contrasting agents. X-ray micro-CT allowed us to image the large blood vessels together with the branching sinusoids of hepatic tissue in three dimensions. Furthermore, interruption of the microvasculature was noted when rats were injected with CC531s colorectal cancer cells indicating the presence of hepatic metastases.     

Electro-optical properties of poly[di(2-thiophenyl)carborane] and its opto-electronic application

Electrochemical and optical properties of a hybrid carborane based polymer called poly(di(2-thiophenyl)carborane) (P1) obtained electrochemically were reported as well as its electrochromic device application. Thiophene donor units and m-carborane acceptor unit were combined under the same umbrella via donor–acceptor–donor approach to obtain di(2-thiophenyl)carborane (1). Contrary to the literature, extreme conditions like highly dried solvent or inert atmosphere were not used for polymerization and characterization. Polymer P1 has an ambipolar character since it exhibited a reversible oxidation peak at a half wave potential (E_1/2) of 1.08 V and a quasi reversible reduction peak at E_1/2 = −1.82 V vs. Ag/AgCl. The polymer film has an optical band gap of 1.95 eV with a maximum absorption band centered at 488 nm. Also, it exhibited multicolor electrochromic behavior between its reduced and oxidized states changing from dark orange to light blue. Furthermore, the electrochromic device prepared based on P1 film was stable and robust.     

COD Fractionation in Wastewater Characterization—The State of the Art

Wastewater characterization is now regarded as an indispensable step yielding all the necessary information for a reliable modelling and design of biological treatment processes. It should mainly include fractionation of the chemical oxygen demand (COD), and assessment of significant kinetic and stoichiometric coefficients. COD fractionation involves identification of inert and biodegradable COD together with readily biodegradable and slowly biodegradable fractions. Experimental methods developed or selected for the assessment of COD fractions should be compatible with the mathematical models defining biological treatment and should yield consistent and reliable values. A critical review of available experimental methodology is provided and values of significant COD components determined in this work and reported in the literature, for different types of domestic and industrial wastewaters are outlined. © 1997 SCI.     

Synthesis and properties of oxalic acid-doped polyaniline

Conductive polyaniline was synthesized in aqueous 1.0M oxalic acid containing 0.1 M aniline by electrochemical and chemical oxidation and characterized by conductivity, solubility, ultraviolet and infrared spectroscopy, and cyclic voltammetry. The solubility experiments showed that the solubility of oxalic acid-doped polyaniline in dimethylsulfoxide and dimethylformaide increased to a certain extent. The soluble part of the polyaniline was free from impurities such as quinones. Cyclic voltammetric studies in oxalic acid medium revealed that aniline exhibited a similar behaviour to that in H₂SO₄ and the polymerization rate was much slower than that in H₂SO₄.     

Product flexibility in selecting manufacturing planning and control strategy

The manufacturing systems capable of producing several products simultaneously are frequently subject to changes in product types due to demand fluctuations. In such systems a product flexible manufacturing planning and control (MPC) strategy is needed to change from one product type to another with minimum deterioration to system performance levels. The objective of this research is to develop a systematic analysis and evaluation approach in order to compare the MRP-push and JIT-pull strategies quantitatively based on a product flexibility measure. A new product flexibility measure is developed based on the sensitivity to change concept and presented together with the implementation in a real manufacturing system. Simulation is used to compare the performance of a JIT-pull with an MRP-push strategy based on performance measures, e.g. manufacturing lead time, work-in-process inventory, backorders, machine utilization and throughput. The performances of the two strategies are evaluated in two scenarios: (i) a single product; (ii) a second product is added (the first product being simple and the second being complex in terms of processing). The impacts of adding the second product on the performance measures for the push and pull strategies are then assessed. A multi-attribute evaluation scheme is used to compare the two strategies where the attribute values are the change in performance measures as the second product is added. The proposed product flexibility measure is utilized in the interpretation of the results.