Preparation and properties of selective polyurethane films and their use for the development of biomedical dopamine sensor

Polyurethane films were synthesized by 3,4-divanillyltetrahydrofuran and different diisocyanates. These prepared polyurethanes were characterized by FT-IR, DSC, DTA, and TGA techniques. For the amperometric applications, synthesized polyurethanes exhibited suitable T_g (°C), good thermal stability and good adhesive properties. In addition, because of their interesting film properties, attempts were made to prepare dopamine-sensing electrode. For this reason, selectivity of film-coated electrodes obtained from the chemically prepared polyurethanes toward electroactive and nonelectroactive species were examined by means of DPV technique. From the electrochemical results obtained, it has been demonstrated that the PU-1-coated electrode can be used for the development of biomedical sensor.     

Flow time analyses of a simulated flexible job shop by considering jockeying

It has been essential to include flexibility in manufacturing policy making since variability in demand and products are considerably increasing. However, it is important to know and to monitor the proper level and type of flexibility that is required to obtain full benefits from it. This paper analyses the effects of flexibility on flow time performance of a simulated job shop. For that purpose, several scenarios are developed under four flexibility levels with two different machine selection rule and three types of dispatching rules. Furthermore, effect of jockeying as a queuing policy on the flow time performance is also investigated through simulation modeling. Results indicated that full flexibility is a preferable state for most of the cases. However, in some cases, chain configurations perform similar results since it combines the benefits of pooling and specialization. In addition, it is observed that a queue control mechanism like jockeying is an effective way to improve performance even though it may increase complexity of controlling policy.     

Effects of different agro-industrial waste as substrates on proximate composition,metals, and mineral contents of oyster mushroom (Pleurotus ostreatus)

The use of agro-industrial waste as substrates for mushroom cultivation is considered a promising management strategy for reducing and valorising these wastes, simultaneously reducing the cost of mushroom cultivation. In this study, oyster mushroom Pleurotus ostreatus were cultivated on twelve substrates composed of either tea waste, lime sawdust, alder sawdust, hornbeam sawdust/shaving, wheat stalk-straw, wheat bran or their composite to determine the proximate composition and accumulation of thirteen elements in their fruiting bodies. The proximate composition of P. ostreatus did not show a significant difference, regardless of the employed substrate. (one-way manova ; F_{(66, 107)} = 1.329, Wilk’s λ = 0.041, P > 0.05). However, their chemical element contents show a statistically significant difference (one-way manova ; F_{(132, 418)} = 32.163, Wilk’s λ = 0.000, P < 0.05). These results were supported by discriminant function and principal component analyses. The highest mean concentrations of six of twelve elements (i.e., Ca, Mg, Na, Zn, Cd and Cr) were recorded in P. ostreatus cultivated on the lime-sawdust substrate. Three health indices viz., estimated daily intake, target hazard quotient (THQ) and total THQ were applied to determine the risk to human health via the consumption of P. ostreatus, suggesting that they are safe for human consumption.     

Influence of T5 heat treatment on the microstructure and lubricated wear behavior of ternary ZnAl40Cu2 and quaternary ZnAl40Cu2Si2.5 alloys

A ternary ZnAl40Cu2 and a quaternary ZnAl40Cu2Si2.5 alloys were produced by permanent mold casting and subjected to T5 heat treatment at a temperature of 150 °C for 24 hours. The structural, mechanical and lubricated wear properties of these alloys were investigated in the as-cast and heat-treated conditions and the results were compared with those of SAE 65 (CuSn12) plain bearing bronze. Microstructure of the ternary alloy consisted of aluminum-rich α, eutectoid conversion product of α+η and ϵ phase located in the interdendritic channels. In addition to these phases, silicon particles were observed in the microstructure of the quaternary alloy. T5 heat treatment caused a considerable amount of reduction in the hardness, tensile strength and wear resistance of ZnAl40-based ternary and quaternary alloys, but improved their ductility and stability. These alloys in the as-cast and heat-treated conditions exhibited lower wear volume or higher wear resistance than SAE 65 bearing bronze. Among the experimental alloys, the optimum mechanical properties and wear performance were obtained from ZnAl40Cu2Si2.5 alloy in both as-cast and heat-treated conditions. Adhesion appeared to be the main wear mechanism for the ZnAl40-based alloys, but abrasion dominated the wear of SAE 65 bronze.     

Porous polyurethane film fabricated via the breath figure approach for sustained drug release

The breath figure (BF) method is an effective process for fabricating porous polymeric films. In this study, we fabricated porous polymer films from thermoplastic polyurethane (PU) through static BF with CHCl₃ as a solvent under 55–80% relative humidity. The porous PU films were prepared within various pore structures and sizes, which were adjustable, depending on the fabrication conditions. The humidity and exposure time were examined as variable parameters affecting the surface morphology, wettability, and cytotoxicity. Atorvastatin calcium, a hyperlipidemic agent, was loaded into the porous films during the casting process, and the drug-loading and drug-releasing behaviors of the porous PU membranes were evaluated. Approximately 60–80% of the drug was released in 14 days. The films exhibited sustained drug-release performances because of the hydrophobicity and nonbiodegradable nature of PU for perivascular drug administration. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47658.