Advanced Materials Research Vol. 1175

Abstract: A thermodynamic model for cellular glass pore-formation has been developed on the basis of natural volcanic silicate and aluminosilicate glasses. The energy expenses for heating the materials, chemical reactions, breaking the structural bonds of water hydrates, evaporation of the released water, and pore formation of the glass mass are determined sequentially. The enthalpy and Gibbs energy of the complex gas-forming agent HNO₃ + SiC are calculated.

Abstract: Aluminium-water reaction is one of the most promising ways to produce clean and economical hydrogen. In this study, the effect of the waste Aluminium foil AA1235 thickness on Aluminium-water reaction process was investigated. The thickness of aluminum used are 6.5 m, 11.5 m and 19.5 m. Aluminum foil was cut by size 20 mm x 30 mm in each thickness variation. The 0.4 M NaOH and 0.01 M NaAlO₂ was added as promoter on the process. The initial composition of the aluminum and the dislocations in the aluminum are also considered. The experimental results was evaluated by the mass reduction and shrinking core models. The initial composition of the aluminum and the dislocations in the aluminum are also considered. The experimental results were evaluated by the mass reduction and shrinking core models. The results obtained that aluminum with thinner thickness can be approximated by the 1-dimensional slab shrinking core model. Aluminum with a thicker thickness can be approached with a mass reduction model. It is also found out that smaller thickness has larger dislocation and better effects of NaAlO₂ resulting higher yield of hydrogen production.

Abstract: In this work, the Sol-Gel dip-coating technique is used to report the effect of thickness and annealing temperature on structural and optical properties of TiO₂ thin films. To study the effect of the annealing temperature, the prepared samples were annealed at different temperatures: 300, 400, and 500 °C for 1 h. By increasing the annealing temperature, an amelioration of the crystalline quality is observed. The best crystalline quality was obtained at 500 °C. Additionally, the band gap value E_g, evaluated from transmission spectra, does not vary with the increasing of the annealing temperature. All the films with different thicknesses present crystalize in the Anatase structure, and the crystallite size value does not practically change with thickness increase. It was also found that the TiO₂ film band gap value decreases with the film thickness increase, demonstrating the possibility of band gap tuning by varying the TiO₂ film thickness.

Abstract: The quality of gel - based silicon, which forms an insulating content to prevent water and sand in oil and gas wells, have been improved. Based on the reaction between the liquid glass and hydrochloric acid, the optimal concentration of the initial reagents for the formation of the gel process was determined. The rheology, initial and final setting time of the silicon based gel, and the temperature dependencies of the gel forming process were also studied by adding 0.1-1.0% (mass ratio) of urea as cross-linking to the Na2SiO3/HCl solution. At the same time, the impact of the obtained gel of the permeability of the rock pores was determined and the filtration characteristics were studied. It has been determined that with 0.1-0.8% mass concentration of the urea added to the Na2SiO3/HCl solution, the setting time of the gel could be regulated according to the well-layer regime. The resulting silicone-based gel can be used as an injection solution that can set in 3-22 hours in oil and gas wells between the temperature of 20-80 °C.

Abstract: The process of mechanically activating chemical bonds usually involves applying external force. Since mechanical chemistry can be performed without solvents or with minimal amounts of solvent (catalytic quantities), it has become an imperative synthetic tool in multiple fields (e.g., physics, chemistry, and materials science) and is an attractive greener method for preparing diverse molecules. Catalysis, organic synthesis, solid-state medicinal preparation, metal complex synthesis, and many other chemistry fields have benefited from sustainable methods. The purpose of this paper is to shed light on the benefits of using mechanochemical methods to produce a pharmaceutical crystal that is composed of dendrimer nanocrystals. Consequently, we describe and examine the importance of mechanical procedures in forming dendrimers and pharmaceutical crystals in this review.

Abstract: Increasing the demand to explore the nanomaterials properties to be used in numerous applications have emerged considerable effort to developing synthesis methods. Herein, Tin oxide (SnO₂) nanosheets have been prepared by a facile one step hydrothermal method using Teflon-lined steel at synthesis temperature of 120 C for 12 hours. As synthesis material were characterized by Field emission scanning electron microscopy (FESEM) and x-ray diffraction (XRD) to revealing the morphology and structural properties. As a result, SnO₂ nanosheets have been obtained with thickness around 15 nm with a clear sheets morphology. XRD pattern showed one phase structural with absence of impurities phases. Optical properties for nanosheets suspended in ethanol were investigated using steady state photoluminescence and UV-Vis absorption technics. The result showed four peaks centered at 380 nm, 445 nm, 475 nm, and 500 nm related to near band to band emission and defects states. Keywords: SnO2, Nanosheets, hydrothermal, XRD

Abstract: The sulfur content present in graphene oxide prepared by Hummers' method has only been addressed by few papers so far. By modified Hammers method we synthesized thermally stable in ambient environment multilayer sulphur-doped graphene oxide. The samples were heat treated in an electrical furnace setup at different ambient temperatures and their crystallite size and linear coefficient of thermal expansion were extracted from Raman band intensity peak ratio as a function of temperature. We found unusually large (in comparison with graphene oxide) contraction on heating of multilayer two weight percent sulphur-doped graphene oxide with carbon to oxygen ratio of 2.3 in a narrow temperature range (308-318 K) with the lowest value of the linear thermal expansion coefficient of -18 ppm 1/K. Based upon an examination of the synthesized sulphur-doped graphene diffractograms, it is suggested that negative thermal expansion stems from the phonon backscattering by the sulphur impurity sites and the edges of the layers. The obtained experimental results have potential practical applications for fabrication of solar cells, sensors, lubricators, thermal actuators and also wavelike (second sound) thermal transport structures.

Abstract: A novel and convenient approach for the fabrication of vinyl functionalized multiwalled carbon nanotube (MWCNT) as a sorbent for organic pollutant is described in this article. In this method, the purified MWCNT is functionalized via a non-covalent strategy using 9-vinyl anthracene, fluorescent active species. The synthesised nanotube was characterised using various techniques such as Fourier transform infrared spectroscopy (FT-IR), UV-Vis. spectroscopic analysis, scanning electron microscopy (SEM), X-ray diffraction technique (XRD), thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and Raman spectroscopy. Effects of concentration, pH and time for the functionalization of MWCNTs were investigated through photoluminescence (PL) studies. The resulting vinyl functionalized MWCNT will act as a promising adsorbent for organic pollutants like p-chlorobenzoic acid.

Abstract: In this study, a synthetic scaffold was prepared from polycaprolactone (PCL) and polyurethane (PU) blend, in a ratio of [2:1] [PCL: PU], using electrospinning technique. Electrospun scaffolds from native PCL and PU were also prepared for comparison, using the same polymer concentration 15% weight/ volume w/v. The detailed microstructure and other properties, like mechanical properties, porosity, and contact angle were investigated and compared between the three prepared scaffolds. Then, the survival, adhesion, proliferation and penetration of rat embryonic fibroblast (REF) cells were evaluated on these three prepared scaffolds after being in vitro cultured with these cells for 21 days, using scanning electron microscope (SEM) analysis and histological analysis. The results showed that, all the studied properties, including mechanical properties and contact angle were enhanced by combining PU with PCL in the [PCL: PU] scaffold. The average diameter of fiber and the average size of pore were suitable and proper for cell attachment, cell proliferation, and also the big average pore size in [PCL: PU] scaffold was enough for cell penetration to form a three- dimension 3-D structure, which is the aim of this study.