Concentration-Dependent, Size-Independent Toxicity of Citrate Capped AuNPs in Drosophila melanogaster

The expected potential benefits promised by nanotechnology in various fields have led to a rapid increase of the presence of engineered nanomaterials in a high number of commercial goods. This is generating increasing questions about possible risks for human health and environment, due to the lack of an in-depth assessment of the physical/chemical factors responsible for their toxic effects. In this work, we evaluated the toxicity of monodisperse citrate-capped gold nanoparticles (AuNPs) of different sizes (5, 15, 40, and 80 nm) in the model organism Drosophila melanogaster, upon ingestion. To properly evaluate and distinguish the possible dose- and/or size-dependent toxicity of the AuNPs, we performed a thorough assessment of their biological effects, using two different dose-metrics. In the first approach, we kept constant the total surface area of the differently sized AuNPs (Total Exposed Surface area approach, TES), while, in the second approach, we used the same number concentration of the four different sizes of AuNPs (Total Number of Nanoparticles approach, TNN). We observed a significant AuNPs-induced toxicity in vivo, namely a strong reduction of Drosophila lifespan and fertility performance, presence of DNA fragmentation, as well as a significant modification in the expression levels of genes involved in stress responses, DNA damage recognition and apoptosis pathway. Interestingly, we found that, within the investigated experimental conditions, the toxic effects in the exposed organisms were directly related to the concentration of the AuNPs administered, irrespective of their size

3D Printed Corrugated Plate Antennas With High Aperture Efficiency and High Gain at X-Band and Ka-Band

A design criterion for a compact 3D printed high gain corrugated plate antenns that has high aperture efficiency and wide bandwidth is presented in this paper. The proposed design criterion is validated numerically and experimentally by fabricating 3D printed and Aluminium prototypes for X-band and Ka-band applications. The proposed antenna structure consists of two layers, where the electromagnetic energy (EM) is launched into a cavity that exists between both layers and the EM energy is coupled to the surface of the second layer. The second layer is the radiating structure which consists of three slots surrounded by a rectangular cavity and periodic corrugations that significantly improve the gain of the antennas. The 3D printed prototypes of the proposed antennas are fabricated and tested to validate the proposed design criterion, and their performance is compared to the Aluminium metallic counterparts. Using 3D printing technology, to fabricate the proposed antennas offer low cost and low weight alternatives to the Aluminium metallic prototypes. The measured results of the fabricated prototypes show high gain, high aperture efficiency, low side lobe level, and low cross polarization performance over a wide bandwidth

Thermally stable PdIn ohmic contacts to n-GaAs via exchange mechanism

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