Investigation of nanosized alumina-binder feedstock rheology for ceramics injection molding (CIM) and survey spark plasma sintering of output green body to obtain transparent alumina

The purpose of this work is to optimize the feed containing alumina-binder nanoparticles for ceramics injection molding to create transparent alumina parts. In this research, two Alumina with and without MgO as sintering aid fabricated via the spark plasma sintering method. Feed fluidity, fracture toughness, density, IR, and visible transmission of SPSed bodies of the sintered pieces were measured. Furthermore, a pin on the disc test was used on the disk to examine the alumina friction coefficient. The results of feed rheology showed that the sample prepared at 90°C had the best conditions as a pseudoplastic fluid for the ceramic injection molding (CIM) method. The results showed that a combination of CIM and spark plasma sintering (SPS) methods cause more visible transmission than conventional SPS of alumina nanopowder. Also, the fracture toughness and hardness of as-obtained transparent alumina were in the range of 3.6 MPa m^0.5 and 20.1 MPa, respectively. The wear rate of the as-obtained transparent sample (4.5 × 10⁻⁷ mm³/N m) was proportional to the alumina grain size (1–4 μm).     

Effects of divalent cations,seawater, and formation brine on positively charged polyethylenimine/dextran sulfate/chromium(III) polyelectrolyte complexes and partially hydrolyzed polyacrylamide/chromium(III) gelation

Polyacrylamide crosslinked with Cr(III) is a common blocking agent that is injected into oil reservoirs to shut off the water flow to features such as fractures and high‐permeability rock to improve the volumetric sweep efficiency during water flooding. This technique is limited to situations where enough gelant can be injected to fill the high‐permeability zones before gelation occurs. Cr(III) may be encapsulated with a high entrapment efficiency in self‐assembling polyelectrolyte complex nanoparticles with effective diameters of about 100–200 nm and formed by the mixture of polyethylenimine and dextran sulfate in nonstoichiometric amounts. The electrostatic interaction between the polyelectrolytes and the Cr(III) is reversible, but diffusion out of the nanoparticles is retarded, and this results in a delay in gelation from minutes or hours to several days in deionized water. Produced and injection waters often contain salts at concentrations comparable to seawater. The effects of these salts were investigated, and we found that the delay in gelation was further extended to as much as 35 days at 40°C and 35 h at 80°C in the presence of divalent ions at seawater concentrations, either alone or in a field brine or seawater; this greatly increases their potential utility. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Thermodynamics of Aluminium in Molten Zinc with the use of Electrochemical Sensors

In the present study the thermodynamics of aluminium in molten Zn‐Al was determined at the temperatures 470, 490 and 520°C with the use of electrochemical sensors. Cell and sensor techniques were used. The following concentration cell was used: Al (pure reference) |Al³⁺ (in fused salt) | [Al]_{in zinc}. It was found that the activity of aluminium shows positive deviation from Raoult's law. The partial heat of solution of aluminium at temperatures between 470 and 520°C for X_Al = 0.004 was determined as = 21882 J. The dilute solution of aluminium in zinc in the range of 0≤X_Al≤0.044 obeys Henry's law. The Wagner's first order interaction coefficient e^Al_Al was determined.     

Glucosamine conjugated iron oxide and graphene oxide nanohybrid for smart drug delivery

Smart drug delivery systems have attracted a lot of attention as one of the new treatment methods for cancer. In this study, a smart drug delivery system carrying anticancer drugs was obtained by the intelligent synthesis of glucosamine (GA)-functionalized graphene oxide (GO)-based iron oxide nanoparticles (Fe₃O₄@GO-GA) using Hummers and chemical co-precipitation processes. Nanohybrids have a high surface area (280.26 m²/g) and superparamagnetic behaviour (Ms = 26.017 emu/g), indicating a significant loading capacity (373.78 mg/mg) and efficiency (96.3%) for pharmaceutical loading. An adsorption study of conventional daunorubicin (DNR) on this carrier showed that the drug release is more prone to occur under acidic conditions (pH = 5.5), at moderately high temperatures (T = 40°C), and in the absence of smart carriers. The toxicity of the smart nanohybrids was examined using the sulphorhodamine B (SRB) assay in Michigan Cancer Foundation-7 (MCF-7) cell lines. The rate of death of cells exposed to smart drug-containing systems in comparison to the systems without GA shows that GA reduces the toxicity of Fe₃O₄@GO.     

A CSO-based approach for secure data replication in cloud computing environment

The Journal of Supercomputing - Cloud computing has a significant impact on information technology solutions for both organizations and researchers. Different users share critical data over the...     

High-efficiency mechanochemical synthesis of Strontium carbonate nanopowder from Celestite

In this study, the conversion of Celestite to SrCO₃ was studied by wet mechanochemical synthesis in a high-energy ball mill and treatment with Na₂CO₃. For this purpose, solid strontium carbonate and soluble Na₂SO₄ were obtained after wet milling of Celestite powder and sodium carbonate. The solid phase was washed with water at room temperature by filter pressing. X-Ray diffraction patterns showed that the SrCO₃ nanopowder was synthesized and conversion boosted with increasing the milling time up to 8 hours Also, Rietveld refinement analysis was used to calculate the fraction of SrCO₃ as well as structural properties of synthesized samples. It was found that initial Celestite could be converted to strontium carbonate with a purity more than 98% using high-energy milling without simultaneous heating. The optimum milling time was determined as 4 hours resulting in formation of nanopowders with an average particle size around 90 nm. Field Emission Scanning Electron Microscopy (FE-SEM), clearly showed the nanoscale structure of the synthesized powders.