Anatase TiO2 nanosheets with high {001} facet exposition were synthesized via a one-pot hydrothermal method. Commercial WO3 nanopowders were then mechanically mixed with the as-synthesized TiO2 to prepare WO3/TiO2 hybrid samples and build the heterojunctions. The physicochemical properties of the samples were characterized by numerous methods, including XRD, Raman, BET, PL, SEM, and TEM. The photocatalytic performance was tested by the oxidation of CO under UV light. The effects of annealing temperature and the mass ratio of WO3 to TiO2 on the photocatalytic activity were also investigated. The results illustrated that pure TiO2 without annealing processing showed the highest oxidation rate compared to all other samples, suggesting that the charge separation by facets is more efficient than WO3-TiO2 heterojunctions.
Synthesis of Fe3O4-Ag nanoparticles (NPs) was implemented via utilizing the method of coprecipitation for synthesizing the Fe3O4 nanoparticles, and reducing silver nitrate (AgNO3) to Ag-nanoparticles, and impregnating the Ag NPs into the Fe3O4 NPs. The synthesized composite material was characterized using the FT-IR, XRD, and the contact angle. The results showed that the Ag NPs were attached to the Fe3O4, and that the composite nanoparticles exhibit hydrophilic behavior. Such properties make these materials a great candidate for oil-water separation related applications.
Three-dimensional (3D) structures fabricated from a 2D material such as graphene have recently attracted huge attention owing to the outstanding electro-mechanical and thermal properties of various types of 2D materials. The interest has expanded to integrate the 2D material into 3D printing structures to form an architected foam. Several studies have focused on fabricating 3D structures from 2D materials using different techniques. In this work, the self-assembly hydrothermal-assisted dip-coating technique has been employed to fabricate graphene foams. The graphene is coated on a 3D printed polymeric scaffold that takes the topology of the mathematically-known triply periodic minimal surfaces (TPMS). A series of tests were performed to measure the multifunctional (electrical, thermal, mechanical) properties of the TPMS-based graphene foam. The results show that these lightweight 3D graphene foams (3DGF) can be used in various applications.
The use of iron-based metal-organic frameworks (MOFs) coated with PEG-folated liposomes is investigated as novel hybrid anticancer nanocarriers. Specifically, using the folate moiety for targeting cancerous cells and ultrasound as an external triggering mechanism is studied. The experimental work examines the encapsulation efficiencies and release profiles of the prepared liposome-coated MOF. The experiments were carried out using an anticancer drug (namely Doxorubicin, DOX) at two different pH values (5.3 and 7.4) with ultrasound. Preliminary results show that the encapsulation efficiency was in the range of 96-98% and the release efficiency was between 96-98% at the investigated pH values within 180 mins.
Electromagnetic interference has been a major concern, especially in health-related matters, industrial pollution, and military functions. In this study, our main purpose is to develop a flexible, lightweight, and high-performance material with high effectiveness for electromagnetic interference (EMI) shielding. We have developed thin films of pure Mxene, as well as heterogeneous layered structures of MWCNTs@MoS2/Mxene. The EMI shielding effectiveness of 1mg MWCNTs@MoS2 and 3mg of MWCNTs@MoS2 are determined as 50 to 60 dB in X band (8.2 to 12.4 GHz), which is better than the pure Mxene. Although by increasing the composition of CNT@MoS2 more, the EMI shielding performance decreases, the heterogeneous films exhibit unprecedented flexibility and durability, thus rendering them with the potential application.
In this preliminary study, polyamide (PA12) based nanocomposites reinforced with different concentrations of multi-walled carbon nanotubes (MWCNTs) were synthesized by using SLS. Initially, printing parameters of SLS were optimized to print the pure and nanocomposites samples. Then printed samples were examined for mechanical and piezoresistive response to evaluate the effect of addition of MWCNTs in the polymer matrix. The nanocomposites samples showed reduction in mechanical properties which might be attributed to change in the interfacial bonding between filler and the matrix as compared to pure PA samples. Microscopic and thermal characterization are required to figure out the cause of reduction in the mechanical properties which is a future work. In terms of piezoresistivity, the sample with lowest concentration of MWCNTs showed highest gauge factor/ sensitivity. The final aim of this study is to fabricate the nanocomposites that can be used in self-sensing applications in the form of strain sensing devices.
As Gulf Cooperating Council countries integrate more renewables into their energy mix, energy system planning becomes increasingly important for technology selection and evaluation. This paper presents a preliminary modeling investigation of the impact of increasing shares of solar power in future electricity sectors on primary energy consumption, environmental emissions and production-demand matching. The results indicate significant seasonal overproduction, which will require to be addressed using appropriate measures.
The relation of the fastest explosive time scale τ e(0) that characterizes the initiation of a homogenous, isochoric autoignition process with the ignition delay time t ign is explored. This investigation is carried-out for six fuels at 0.5 ≤ φ ≤ 4.0, p(0)=2, 10, 20 atm and T (0)= 900, 1100, and 1350 K. It is shown that the variation of τ e(0)/t ign is small in the cases of hydrogen and methanol, in all cases considered. However, the variation of this ratio is significant for methane and n-heptane for most of the cases considered. For iso-butanol, the variation is relatively small, except the cases when T (0) = 1350 K. Finally, for DME, the variation of τ e(0)/t ign is relatively small.
Heated and unheated flows with forced convection over two fixed circular cylinders in tandem are studied numerically for 80≤Re≤250 and 1≤T^*≤2.3. Three different spacing ratios (L/D)=[2,4,8] are considered under three heating conditions. The scenarios considered are (1) heated upstream and unheated downstream cylinders, (2) unheated upstream and heated downstream cylinders and (3) heated upstream and downstream cylinders. These scenarios represent the limiting case for a cross-flow heat exchanger, where the downstream tubes are at increasingly lower or higher temperature for cooling or heating, respectively. The global aerodynamic forces on the cylinder as vortices shed was investigated. The flow is visualized by plotting the streamlines, temperature fields, and velocity magnitude contours for the different spacing ratios and compared to the flow regimes in literature namely, Extended-body, Reattachment, and Co-shedding regimes. The surface heat transfer coefficients are analyzed for different scenarios.
The influence of streamwise oscillations on the lift and drag coefficients over isothermal and non-isothermal circular cylinder is numerically studied in this work. Temperature difference of 300, 600, and 900 K is used between the cylinder wall and the incoming fluid flow at Reynolds number of 100. Air is used as the fluid and the temperature dependent properties of air are used for the analysis. Numerical simulation is done on Ansys/fluent with O-type structured mesh. The vibration of the circular cylinder is induced via user defined function at a frequency ratio of 0.5, 1, and 2, with the natural frequency of the cylinder being 2.5 Hz marking its Strouhal number of 0.167.
