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...     

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.     

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     

The microwave-assisted synthesis and characterization of novel metal-free and metallophthalocyanines peripherally fused to four 13-membered diazadithia macrocycles

The novel tetrasubstituted metal-free phthalocyanine and metallophthalocyanines 7, bearing four 13-membered diazadithia macrocycle moieties at peripheral positions were synthesized by cyclotetramerization of the corresponding phthalonitrile derivative in a multi-step reaction sequence. The metal-free phthalocyanine was synthesized by microwave irradiation of the corresponding dicyano compound in 2-(dimethylamino)ethanol for 10 min. Metallophthalocyanines were obtained from the respective dicyano derivative and corresponding anhydrous metal salts NiCl₂ and ZnCl₂, CoCl₂, CuCl₂, respectively, by microwave irradiation in 2-(dimethylamino)ethanol at 175 °C, 350 W for 10 min. The new compounds were characterized by a combination of IR, ¹H NMR, ¹³C NMR, UV–vis, elemental analysis and MS spectral data.     

Zinc oxide nanowire enhanced multifunctional coatings for cotton fabrics

Zinc oxide (ZnO) nanowires have been grown on cotton fabric to impart self-cleaning, superhydrophobicity and ultraviolet (UV) blocking properties. ZnO nanowires were grown by the microwave assisted hydrothermal method and subsequently functionalized with steraic acid to obtain a water contact angle of 150°, showing their superhydrophobic nature which is found to be stable up to 4 washings. UV protection of the resulting cotton fabric was also examined and significant decrease in the transmission of UV range was observed. Self-cleaning activity of the ZnO nanowire coated cotton fabric was also studied and it showed considerable degradation of methylene blue under UV light irradiation. These results suggest that ZnO nanowires could form ideal multifunctional coatings for textiles.     

Mechanical and Thermal Properties of 3D-Printed Biocomposites of Polylactic Acid and Thermally Modified Wood Flour with Silver Nanoparticles

This study investigates the effects of thermal treatment and silver nanoparticles on the mechanical and thermal properties of additively manufactured wood/polylactic acid (PLA) specimens. The 5 and 10 wt% additions of the wood flour into the PLA matrix are done in the twin screw extruder. The test specimens are produced from the filaments with a diameter of 1.75 mm using 3D printer. The mechanical properties of the 3D-printed wood/PLA specimens are affected by the wood flour content, thermal treatment of wood, and silver nanoparticles. The 3D-printed neat PLA specimens have better mechanical properties than the wood flour-filled PLA specimens. The bending strength of the specimens enhances with increasing wood flour content while the tensile strength decreases. The increases in the mechanical properties reveal that the thermal treatment of the wood improves the compatibility between wood and PLA matrix, which hereby improves the interfacial adhesion. The addition of the silver nanoparticles positively affects the mechanical properties and it is more compatible with thermally modified wood particles as compared to the untreated wood particles.