Reduced erbium-doped ceria nanoparticles: one nano-host applicable for simultaneous optical down- and up-conversions

This paper introduces a new synthesis procedure to form erbium-doped ceria nanoparticles (EDC NPs) that can act as an optical medium for both up-conversion and down-conversion in the same time. This synthesis process results qualitatively in a high concentration of Ce³⁺ ions required to obtain high fluorescence efficiency in the down-conversion process. Simultaneously, the synthesized nanoparticles contain the molecular energy levels of erbium that are required for up-conversion. Therefore, the synthesized EDC NPs can emit visible light when excited with either UV or IR photons. This opens new opportunities for applications where emission of light via both up- and down-conversions from a single nanomaterial is desired such as solar cells and bio-imaging.     

Evaluation of angiotensin I-converting enzyme (ACE) inhibitory activities of smooth hound (Mustelus mustelus) muscle protein hydrolysates generated by gastrointestinal proteases: identification of the most potent active peptide

In this study, smooth hound protein hydrolysates (SHPHs), obtained by treatment with various gastrointestinal proteases, were analyzed for their angiotensin I-converting enzyme (ACE) inhibitory activities. Protein hydrolysates were obtained by treatment with crude alkaline enzyme extract, low molecular weight (LMW) alkaline protease, trypsin-like protease and pepsin from Mustelus mustelus, and bovine trypsin. All hydrolysates exhibited inhibitory activity toward ACE. Hydrolysate generated with alkaline protease extract displayed the highest ACE inhibitory activity, and the higher inhibition activity (82.6% at 2 mg/mL) was obtained with a hydrolysis degree of 18.8%. This hydrolysate was then fractionated by size exclusion chromatography on a Sephadex G-25 into five major fractions (P₁–P₅). ACE inhibitory activities of all fractions were assayed, and P₃ was found to display a high ACE inhibitory activity (62.24% at 1 mg/mL). P₃ was then fractionated by reversed-phase high-performance liquid chromatography (RP-HPLC) and ten fractions of ACE inhibitors were found (F₁–F₁₀). Sub-fraction F₃ showed the strongest ACE inhibitory activity, being able to suppress more than 60% of initial enzyme activity at a concentration of 100 μg/mL. The amino acid sequence of peptide F₃ was determined by ESI/MS and ESI–MS/MS as Ala-Gly-Ser, and the IC₅₀ value for ACE inhibitory activity was 0.13 ± 0.03 mg/mL. Further, purified peptide F₃ maintained inhibitory activity even after in vitro digestion with gastrointestinal proteases in order to demonstrate gastrointestinal stability digestion to enable oral application. These results indicate that smooth hound protein hydrolysate possesses potent antihypertensive activity.     

Experimental study on minimal nanolubrication with surfactant in the turning of titanium alloys

The superiority of minimal nanolubrication for effective, efficient and cleaner machining environment has been widely discussed in the literature. However, due to their high surface energy, nanoparticles coagulate or agglomerate easily, which makes it difficult to disperse them in the base fluid. Hence, the addition of a small amount of surfactant should be able to overcome this issue. This research elucidates and extends fundamental knowledge regarding the effect of a sodium dodecyl benzene sulfonate surfactant mixed with different nanoparticle concentrations towards the sustainable machining of titanium alloy using design of experiment methodology. The experimental results indicate that the inclusion of a sodium dodecyl benzene sulfonate surfactant in aluminium oxide nanolubricant provides the best lubricating properties for the machining of the titanium alloy. At 0.4 wt% of nanoparticles and a feed rate of 0.1 mm/rev, minimum values of surface roughness and power consumption can be achieved. Meanwhile, minimal tool wear can be attained by application of a 0.6 wt% nanoparticle concentration and 0.1 mm/rev feed rate. Further statistical analyses emphasized that the feed rate was the most significant factor that influenced the surface roughness and power consumption, while the mixture of nanoparticles with surfactant and feed rate has the greatest effect on the tool wear resistance of the cutting insert.     

Numerical and experimental investigation of parabolic trough collector with focal evacuated tube and different working fluids integrated with single slope solar still

This study deals with the design and fabrication of parabolic trough solar collectors (PTCs) used to increase the yield of a single slope solar still. The designed parabolic trough solar collector is investigated numerically using Ansys Fluent 18.2. The proposed solar still is coupled with a parabolic trough solar collector with an evacuated tube receiver in its focal axis using different working fluids. The working fluids are water (case 1), oil (case 2), and nano-oil (CuO/mineral oil 3% vol; case 3). In the case when the working fluid is not water, then a heat exchanger serpentine should be used in the solar still basin. The PTC has a rim angle of 82° and an aperture width of 0.9 m and length of 2.8 m. An assessment of the performance for the studied systems was accomplished under the weather conditions of Ismailia, Egypt, during summer months, June, July, and August 2019. The outcomes of closed-loop working fluids different flow rates are investigated. The experimental results of the accumulated freshwater productivities record 2.955, 3.475, 4.29, and 5.04 L m⁻² d⁻¹ for the traditional solar still and the modified cases 1 to 3 solar stills, respectively. The modified solar still in case 3 has the highest daily accumulated freshwater productivity with a percentage increase of 71.2% than the traditional solar still. The maximum daily efficiency is 46% and 26.9% for the traditional and modified (case 3) solar stills, respectively. The cost of 1 L of fresh water is 0.057 and 0.062 $/L for the traditional and the modified (case 3) solar stills, respectively.     

Peristaltic motion with heat and mass transfer of nano-Williamson fluids in two layers

In this paper, we have investigated the peristaltic motion with heat and mass transfer through a vertical channel divided into two equal regions, the right region filled with a clear non-Newtonian fluid obeying the Williamson model and the left region with a nano-Williamson fluid. The system is stressed by a gravity force with a uniform external magnetic field. The problem is modulated mathematically with a system of coupled nonlinear partial differential equations that describe the velocities, temperatures, and concentration of the fluids. The system of nondimensional, nonlinear, and partial differential equations is solved analytically with the homotopy perturbation method after using the approximations of low Reynolds number and long wavelength. The obtained solutions are functions of the physical parameters of the problem. Then, the effects of these parameters on velocities, temperatures, and concentration are discussed numerically and illustrated graphically through a set of figures. It is found that the parameters play an important role in controlling the solutions. It is shown that the stream function decreases on the left side and increases on the right side with an increase in the Wissenberger parameter and thermal conductivity ratio. Also, the temperature in the two regions increases with an increase in the thermophoretic parameter, whereas it decreases with an increase in the Brownian motion parameter. Furthermore, the concentration increases with an increase in the Brownian motion parameter and decreases with an increase in the thermophoretic parameter.