Microstructural and technological investigation of bone China reformulated with nepheline syenite and quartz addition

In this study, bone china body was reformulated by completely replacing Cornish stone with nepheline syenite and quartz. Effect of controlled milling/mixing on the technological properties and microstructural evolution was also studied. Specimens prepared both from reformulated and controlled milled/mixed bodies were sintered between 1200 and 1250°C with 25°C increment. Sintering and technological properties of reformulated bodies were not being adversely affected but conversely, the measured flexural strength values (55 MPa) were half of the value that was published for bone china (100 MPa). Microstructural investigations showed that enlarged pore formation was the reason for strength reduction. However, improvement in particle packing by controlled milling/mixing eliminated enlarged pore formation and in response, flexural strength values increased to conventionally quoted levels. Detailed microstructural investigations revealed that the reason behind enlarged pore formation was heterogeneous distributions of body components, especially CaO and quartz grains. It was suggested that variations of CaO and SiO₂ to form improper ratio between them would affect the viscosity of glassy phase and crystallization, which would prevent gases in pores to dissolve away. The obtainment of homogenous distribution of body components by controlled milling/mixing has a strong influence on the evolution of microstructure and improvement of technological properties.     

A Method to Improve Gamma Energy Resolution of BC-420 Type Organic Scintillation Detector

Instruments and Experimental Techniques - Currently, plastic (organic) scintillators are using in new type positron emission tomography (PET) devices such as J-PET. But, these type scintillators...     

A new Schiff base: Synthesis,characterization and optimization of metal ions-binding properties

In this study, a new Schiff base (H₄TSTE) was synthesized and characterized by elemental analysis, FT-IR, NMR and MS spectral data. Liquid–liquid extraction process was performed for removal of Cu(II), Mn(II), Ni(II), Pb(II) and Zn(II) from aqueous solutions by means of H₄TSTE. The extractions were investigated depending on the concentration of picric acid, metal ion and H₄TSTE ligand. Response surface methodology (RSM) was first applied to optimize metal ion-binding properties of H₄TSTE. The extraction efficiency was estimated to be >98% for all metals by models. Under the same conditions, the extraction efficiency was experimentally found to be >97% with a relative standard deviation within ±0.10 (N = 4), indicating the suitability of the models.     

Which Type of Trust for Inter-firm Learning?

This study investigates the association between types of trust and inter-firm learning in buyer–supplier exchanges in an industrial cluster. More specifically, the study explores the impact of trust types on knowledge sharing among manufacturer and retailer SMEs in a furniture cluster. The results of empirical data from 158 manufacturers suggest no significant association between trust based on competence, reliability and predictability and inter-firm learning and a significant positive association between trust based on goodwill, benevolence and non-opportunism and inter-firm learning. The study findings integrate research on the relational and knowledge-related aspects of knowledge exchange at the dyadic inter-firm level.     

Effect of cesium salt of tungstophosphoric acid (Cs-TPA) on the properties of sulfonated polyether ether ketone (SPEEK) composite membranes for fuel cell applications

We have prepared composite membranes for fuel cell applications. Cesium salt of tungstophosphoric acid (Cs-TPA) particles was synthesized by aqueous solutions of tungstophosphoric acid and cesium hydroxide and, Cs-TPA particles and sulfonated (polyether ether ketone) (SPEEK) with two sulfonation degrees (DS), 60 and 70%have been used. We examined both the effects of Cs-TPA in SPEEK membranes as functions of sulfonation degrees of SPEEK and the content of Cs-TPA. The performance of the composite membranes was evaluated in terms of water uptake, ion exchange capacity, proton conductivity, chemical stability, hydrolytic stability, thermal stability and methanol permeability. The morphology of the membranes was investigated with SEM micrographs. Increasing sulfonation degree of SPEEK from 60 to 70 caused agglomeration of the Cs-TPA particles. The methanol permeability was reduced to 4.7 × 10⁻⁷ cm²/s for SPEEK (DS: 60%)/Cs-TPA membrane with 10 wt.% Cs-TPA concentration, and acceptable proton conductivity of 1.3 × 10⁻¹ S/cm was achieved at 80 °C under 100% RH. The weight loss at 900 °C increased with the addition of inorganic particles, as expected. The hydrolytic stability of the SPEEK/Cs-TPA based composite membranes was improved with the incorporation of the Cs-TPA particles into the matrix. We also noted that SPEEK60/Cs-TPA composite membranes were hydrolytically more stable than SPEEK70/Cs-TPA composite membranes. On the other hand, Methanol, water vapor, and hydrogen permeability values of SPEEK60 composite membranes were found to be lower than that of Nafion^®.     

Synthesis of antibacterial amphiphilic elastomer based on polystyrene-block-polyisoprene-block-polystyrene via thiol-ene addition

A new type of amphiphilic antibacterial elastomer has been described. Thermoplastic elastomer, polystyrene–block-polyisoprene–block-polystyrene (PS–b-PI–b-PS) triblock copolymer was functionalized in toluene solution by free radical mercaptan addition in order to obtain an amphiphilic antibacterial elastomer. Thiol terminated PEG was grafted through the double bonds of PS–b-PI–b-PS via free radical thiol-ene coupling reaction. The antibacterial properties of the amphiphilic graft copolymers were observed. The original and the modified polymers were used to create microfibers in an electro-spinning process. Topology of the electrospun micro/nanofibers were studied by using scanning electron microscopy (SEM). The chemical structures of the amphiphilic comb type graft copolymers were elucidated by the combination of elemental analysis, ¹H NMR, ¹³C NMR, GPC and FTIR.     

Separation of gold(III) ions from copper(II) and zinc(II) ions using thiourea–formaldehyde or urea–formaldehyde chelating resins

Thiourea–formaldehyde (TF) and urea–formaldehyde (UF) chelating resins were synthesized and these resins were used in the separation of gold(III) ions from copper(II) and zinc(II) base metal ions. In the experimental studies, the effect of acidity on gold(III) uptake and gold(III) adsorption capacities by batch method, and loading and elution profiles of gold(III) ions, gold(III), copper(II), and zinc(II), dynamic adsorption capacities and the stability tests of TF and UF resins by column method were examined. By batch method, the optimum acidities were found as pH 2 and 0.5M HCl, and gold(III) adsorption capacities in the solutions including copper(II) and zinc(II) ions were obtained as 0.088 and 0.151 meq Au(III)/g for UF and TF resins, respectively. On the other hand, by column method, the dynamic adsorption capacities were calculated as 0.109 meq Au(III)/g with TF, 0.023 meq Au(III)/g with UF, 0.015 meq Cu(II)/g with TF, 0.0057 meq Cu(II)/g with UF, and under 6.1 × 10^?5 meq Zn(II)/g with TF or UF. TF resin was more effective in the separation and the concentration of gold(III) ions from copper(II) and zinc(II) ions than UF resin. It was seen that sulfur atoms contributed the gold(III) adsorption comparing with oxygen atoms. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009