Mamdouh El Haj Assad

Plasmonic Metaparticles on a Blackbody Create Vivid Reflective Colors for Naked‐Eye Environmental and Clinical Biodetection

Plasmonic dipoles are famous for their strong absorptivity rather than their reflectivity. Here, the as-yet unknown specular reflection and the Brewster effect of ultrafine plasmonic dipoles, metaparticles, are introduced and exploited as the basis of new design rules for advanced applications. A configuration of Plasmonic metaparticles on a blackbody is demonstrated and utilized for the design of a tailored perfect-colored absorber and for visual detection of environmental dielectrics that is not readily done by extinction plasmonics. Moreover, the Plasmonic Brewster Wavelength (PBW) effect is introduced as a new platform for the naked-eye and bulk biodetection of analytes. The technique operates based on slight changes of molecular polarizability which is not detectable via conventional plasmon resonance techniques. As a specific highlight, the clinical applicability of the PBW method is demonstrated while addressing the transduction plasmonic techniques challenge in detection of bulk refractive index changes of the healthy and diseased human serum exosomes. Finally, the sputtering-based fabrication method used here is simple, inexpensive, and scalable, and does not require the sophisticated patterning approach of lithography or precise alignment of light coupling for the biodetection.

Flow and Heat Transfer in a Driven Cavity with Two Cylinders

Mixed convection in a lid-driven square cavity with symmetrically placed circular cylinders is studied numerically. The effect of thermal boundary conditions imposed on the two cylinders and the location of the two cylinders on the fluid-flow and heat transfer characteristics within the cavity is studied for a range of Richardson numbers at a fixed Reynolds number. Detailed analyses of velocity and temperature distributions are presented with isotherms, streamlines, and the local Nusselt number. The effect of the varying Richardson number on the local Nusselt number along the walls of the cavity and the circular cylinders is presented for the different thermal boundary conditions and cylinder locations considered in this work. It is seen that changing the boundary condition on one of the cylinders from isothermal to adiabatic has minimal effect on the distribution of the local Nusselt number on the wall and the hot cylinder. The present results show that the locations of hot and cold cylinders along the v...

Characterization of natural habitats and diversity of Libyan desert truffles

Desert truffles have traditionally been used as food in Libya. Desert truffle grows and gives fruit sporadically when adequate and properly distributed rainfall occurs with existence of suitable soil and mycorrhizal host plant. The present study aimed to identify and characterize two kinds of wild desert truffles from ecological and nutritional points that were collected from the studied area. The truffle samples were identified as Terfezia (known as red or black truffle) and Tirmania (known as white truffle). The nutritional values (protein, lipid and carbohydrate) of both Libyan wild truffle (Terfezia and Tirmania) were determined on a dry weight basis and result showed that Tirmania and Terfezia contained 16.3 and 18.5% protein, 6.2 and 5.9% lipid, 67.2 and 65% carbohydrate, respectively, in ascocarp biomass. The soil pH of the upper and lower regions of the Hamada Al-Hamra ranged between 8.2 and 8.5 giving suitable conditions for fructification. The plants, Helianthemum kahiricum and Helianthemum lippii were the dominant plants in Hamada Al-Hamra region found to form a mycorrhiza with desert truffles. The phylogenetic analysis of the genomic rDNA ITS region showed that, out of five collections three represented Tirmania pinoyi (Maire) Malencon, one Tirmania nivea (Desf.) Trappe, and one Terfezia boudieri Chatin.