The use of bio-based polymers in place of conventional polymers gives positives effects in the sense of reduction of environmental impacts and the offsetting of petroleum consumption. As such, in this study, jatropha oil was used to prepare epoxidized jatropha oil (EJO) by the epoxidation method. The EJO was used to prepare a shape memory polymer (SMP) by mixing it with the curing agent 4-methylhexahydrophthalic anhydride (MHPA) and a tetraethylammonium bromide (TEAB) catalyst. The resulting bio-based polymer is slightly transparent and brown in color. It has soft and flexible properties resulting from the aliphatic chain in jatropha oil. The functionality of SMP was analyzed by Fourier transform infrared (FTIR) spectroscopy analysis. The thermal behavior of the SMP was measured by thermogravimetric analysis (TGA), and it showed that the samples were thermally stable up to 150 °C. Moreover, the glass transition temperature characteristic was obtained using differential scanning calorimetry (DSC) analysis. The shape memory recovery behavior was investigated. Overall, EJO/MHPA was prepared by a relatively simple method and showed good shape recovery properties.
A low cost, with high performance, reduced graphene oxide (RGO) Ultra-wide Band (UWB) array sensor is presented to be applied with a technique of confocal radar-based microwave imaging to recognize a tumor in a human brain. RGO is used to form its patches on a Taconic substrate. The sensor functioned in a range of 1.2 to 10.8 GHz under UWB frequency. The sensor demonstrates high gain of 5.2 to 14.5 dB, with the small size of 90 mm × 45 mm2, which can be easily integrated into microwave imaging systems and allow the best functionality. Moreover, the novel UWB RGO array sensor is established as a detector with a phantom of the human head. The layers' structure represents liquid-imitating tissues that consist of skin, fat, skull, and brain. The sensor will scan nine different points to cover the whole one-sided head phantom to obtain equally distributed reflected signals under two different situations, namely the existence and absence of the tumor. In order to accurately detect the tumor by producing sharper and clearer microwave image, the Matrix Laboratory software is used to improve the microwave imaging algorithm (delay and sum) including summing the imaging algorithm and recording the scattering parameters. The existence of a tumor will produce images with an error that is lower than 2 cm.
The size-controlled synthesis of liquid metal nanoparticles is necessary in a variety of applications. Sonication is a common method for breaking down bulk liquid metals into small particles, yet the influence of critical factors such as liquid metal composition has remained elusive. Our study employs high-speed imaging to unravel the mechanism of liquid metal particle formation during mechanical agitation. Gallium-based liquid metals, with and without secondary metals of bismuth, indium, and tin, are analyzed to observe the effect of cavitation and surface eruption during sonication and particle release. The impact of the secondary metal inclusion is investigated on liquid metals' surface tension, solution turbidity, and size distribution of the generated particles. Our work evidences that there is an inverse relationship between the surface tension and the ability of liquid metals to be broken down by sonication. We show that even for 0.22 at. % of bismuth in gallium, the surface tension is significantly decreased from 558 to 417 mN/m (measured in Milli-Q water), resulting in an enhanced particle generation rate: 3.6 times increase in turbidity and ∼43% reduction in the size of particles for bismuth in gallium liquid alloy compared to liquid gallium for the same sonication duration. The effect of particles' size on the photocatalysis of the annealed particles is also presented to show the applicability of the process in a proof-of-concept demonstration. This work contributes to a broader understanding of the synthesis of nanoparticles, with controlled size and characteristics, via mechanical agitation of liquid metals for diverse applications.