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Objective: The objective of this study was to prepare nanosuspension of a practical water insoluble antiulcer drug which is lafutidine to enhance the solubility, dissolution rate with studying the effect of different formulation variables to obtain the best formula with appropriate physical properties and higher dissolution rate.Methods: Nanosuspension of lafutidine was prepared using solvent anti-solvent precipitation method using Polyvinylpyrrolidone K-90(PVP K-90) as the stabilizer. Ten formulations were prepared to show the effect of different variables in which two formulations showed the effect of stabilizer type, three formulations showed the effect of stabilizer concentration, two formulations showed the effect of combination of polymer with surfactant such as tween 80, three formulations show the effect of stirring speed and three formulations prepare to show the effect of addition of co-surfactant such as tween 20. All these formulations are evaluated for their particle size and entrapment efficiency and in vitro release. The selected one was evaluated for zeta potential, scanning electron microscope, atomic force microscopy, Fourier transforms infrared spectroscopy, differential scanning calorimetry, saturation solubility and stability study.Results: The formulations (F3-F10) were in the nano size. The optimum concentration of the stabilizer was in the formulation when the drug: polymer: surfactant ratio 1:4:4 and the optimum stirring speed was 1500 rpm. Dramatic effect on the particle size reduction was found by the addition of co-surfactant (tween 20) in formulation F7 that has a particle size 15.89±1.8 nm. The selected formula F7 showed an enhanced dissolution profile (10 min) compared to the pure drug at all-time intervals.Conclusion: The results show that the formulation that contains drug: PVP-K90: tween 80: tween 20 in ratio 1:4:2:2 is the best one and can be utilized to formulate lafutidine nanosuspension.

Massive improvements in the thermophysical properties of nanofluids over conventional fluids have led to the rapid evolution of using multiwalled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs) in the field of heat transfer. In this study, the heat transfer and entropy generation abilities of MWCNTs/GNPs hybrid nanofluids were explored. Experiments on forced convective flow through a brass microtube with 300 µm inner diameter and 0.27 m in length were performed under uniform heat flux. MWCNTs/GNPs hybrid nanofluids were developed by adding 0.035 wt.% GNPs to MWCNTs water-based nanofluids with mass fractions of 0.075–0.125 wt.%. The range of the Reynolds number in this experiment was maintained at Re = 200–500. Results showed that the conventional approach for predicting the heat transfer coefficient was applicable for microtubes. The heat transfer coefficient increased markedly with the use of MWCNTs and MWCNTs/GNPs nanofluids, with increased pressure dropping by 12.4%. Results further showed a reduction by 37.5% in the total entropy generation rate in microtubes for hybrid nanofluids. Overall, MWCNTs/GNPs hybrid nanofluids can be used as alternative fluids in cooling systems for thermal applications.

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