Manufacturing of Aluminum Nano-Composites Reinforced with Nano-Copper and High Graphene Ratios Using Hot Pressing Technique

In this study, the nano-aluminum powder was reinforced with a hybrid of copper and graphene nanoplatelets (GNPs). The ratios of GNPs were 0 wt%, 0.4 wt%, 0.6 wt%, 1.2 wt% and 1.8 wt%. To avoid the reaction between aluminum and graphene and, consequently, the formation of aluminum carbide, the GNP was first metalized with 5 wt% Ag and then coated with the predetermined 15 wt% Cu by the electroless coating process. In addition, the coating process was performed to improve the poor wettability between metal and ceramic. The Al/(GNPs-Ag)Cu nanocomposites with a high relative density of 99.9% were successfully prepared by the powder hot-pressing techniques. The effects of (GNPs/Ag) and Cu on the microstructure, density, hardness, and compressive strength of the Al-Cu nanocomposite were studied. As a result of agitating the GNPs during the cleaning and silver and Cu-plating, a homogeneous distribution was achieved. Some layers formed nano-tubes. The Al4C3 phase was not detected due to coating GNPs with Cu. The Cu9Al4 intermetallic was formed during the sintering process. The homogeneous dispersion of Cu and different ratios of GNs, good adhesion, and the formation of the new Cu9Al4 intermetallic improved in hardness. The pure aluminum sample recorded 216.2 HV, whereas Al/Cu reinforced with 1.8 GNs recorded 328.42 HV with a 51.9% increment. The compressive stress of graphene samples was improved upon increasing the GNPs contents. The Al-Cu/1.8 GNs sample recorded 266.99 MPa.

Enhancement of Physical Properties and Corrosion Resistance of Al-Cu-Al2O3/Graphene Nanocomposites by Powder Metallurgy Technique

In this study, we enhanced the adhesion of graphene nanosheets to achieve homogeneous dispersion, consequently improving the electrical and thermal conductivity, coefficient of thermal expansion, and corrosion resistance with an aluminum matrix containing up to 1.5 wt. % graphene. First, 2.5 wt. % Al₂O₃ and varying ratios of graphene up to 1.5 wt. % were coated with 5 wt. % silver nanoparticles to metalize their surfaces. Predetermined portions of coated alumina and graphene were mixed with Al/10 wt. % Cu powder for 45 h. Mixed samples were compacted under 600 MPa and sintered at 565 °C in a vacuum furnace for 60 min with a low heating rate of 2 °C/min. The strengthening effect of the added materials on the density, microstructure, electrical and thermal conductivities, thermal expansion, and corrosion behavior of aluminum were investigated. Excellent adhesion and homogeneous dispersion of the investigated reinforcements were achieved. Three phenomena were observed: (1) an improvement in the densification, electrical and thermal conductivity, thermal expansion, and corrosion rate by adding 10 wt. % Cu to the aluminum matrix; (2) deterioration of the properties of Al/10 wt. % Cu with the addition of 2.5 wt. % alumina nanoparticles; and (3) improved properties with the addition of graphene nanosheets up to 1 wt. % and a decrease in property values beyond 1.5 wt. % graphene content due to the formation of agglomerations and pores in the metal matrix.

Molecular signalling of a novel curcumin derivative versus Tadalafil in erectile dysfunction

The efficacy of a novel curcumin derivative (NCD) versus tadalafil in erectile signalling was assessed. Ten control male rats and 50 diabetic male rats were used and divided into the following: diabetic (DM), curcumin (CURC), NCD, tadalafil and NCD combined with tadalafil rat groups. Cavernous tissue gene expression of heme oxygenase-1 (HO-1), Nrf2, NF-B and p38, enzyme activities of heme oxygenase (HO) and nitric oxide synthase (NOS), cGMP and intracavernosal pressure (ICP)/mean arterial pressure (MAP) were assessed. Results showed that 12 weeks after induction of diabetes, erectile dysfunction (ED) was confirmed by the significant decrease in ICP/MAP, a significant decrease in cGMP, NOS, HO enzyme activities, a significant decrease in HO-1 gene and a significant increase in NF-Ҡβ, p38 genes. Administration of all therapeutic interventions led to a significant increase in ICP/MAP, cGMP levels, a significant increase in HO-1 and NOS enzymes, a significant increase in HO-1, and Nrf2 gene expression, and a significant decrease in NF-Ҡβ, p38 gene expression. NCD or its combination with tadalafil showed significant superiority and more prolonged duration of action. In conclusion, a tendency was observed that CURC and NCD have high efficacy and more prolonged duration of action in enhancing erectile function.