In situ synthesis of leucite-based feldspathic dental porcelain with minor kalsilite and Fe2O3 impurities

K-Feldspar was used as a raw material for in situ synthesis of leucite particles by solid-state reaction method. Prior to synthesis of leucite, K-Feldspar was treated by oxalic acid (C₂H₂O₄) to eliminate Fe content. The parameters affecting the structure and amount of Fe in K-Feldspar was investigated to reach an optimal leaching condition. Next, kasilite removal was studied by introducing CaF₂ to the composition of dental porcelain. To synthesis leucite, the prepared materials were heated up to 1450°C for 3 hours until fusion phenomena occurred, then cooled down to 865°C to permit the leucite crystals nucleate and grow. To find out the chemical composition of powder, XRF, EDX, and Atomic absorption spectroscopy were used. Fourier Transform Infrared Spectroscopy and X-Ray Diffractometer and Scanning Electron Microscopy were employed to study the structure of mineral. Spectrophotometry was chosen to analyze whiteness index of powder after acid treatment. Differential Thermal Analysis was employed to determine the crystallization temperature. Results indicated a dramatic decrease in Fe content (0.018%wt) by employing C₂H₂O₄ as a leachant at 50°C. In addition, whiteness index of 91% was achieved through this procedure for raw feldspar. Finally, 1%wt of CaF₂ prevented formation of kalsilite.     

Latent Dirichlet allocation (LDA) and topic modeling: models,applications, a survey

Multimedia Tools and Applications - Topic modeling is one of the most powerful techniques in text mining for data mining, latent data discovery, and finding relationships among data and text...     

Modeling the micro-scale static friction coefficient of the MEMS silicon surfaces affected by Ag and Au deposition using the thermal evaporation method

In different macro-scale applications, regarding what should be done, many of the prepared surfaces are immediately used after machining with no limitation. Since the micro-electromechanical applications have different conditions, their different properties, such as friction and adherence, must be checked. In the present study, using the thermal evaporation method, the silver and gold layers with different thicknesses were deposited on the silicon surfaces widely used in micromechanical systems (e.g. micro-assembly). Thereafter, the effects of the deposition on the geometrical properties of the surfaces were studied. Also, the effects of the deposition on the adherence and friction properties of the surfaces were examined by modeling the geometrical condition. To this end, the height function distribution was used to exploit the surface friction model in conjunction with the DMT surface adhesion model. The results show the extent to which gold affects the adhesion and friction properties of the coated surfaces.     

Toward a general framework for jointly processor-workload empirical modeling

The Journal of Supercomputing - The complexity of state-of-the-art processor architectures and their consequent vast design spaces have made it difficult and time-consuming to explore the best...     

Improving the Flexural Properties of E-Glass Fibers/Epoxy Isogrid Stiffened Composites through Addition of 3-Glycidoxypropyltrimethoxysilane Functionalized Nanoclay

Silicon - This research work investigates the effect of silane functionalized nanoclay on the flexural response of E-glass/epoxy isogrid stiffened composite (IGSC). To do so, the sodium...     

The phase and morphological evolution of Ti3SiC2 MAX phase powder after HF treatment

The aim of this study is to investigate the phase and morphological evolution of the prepared Ti₃SiC₂ MAX phase powder after immersion in hydrofluoric acid (HF) solution for 24, 72, 96 and 120?h. The phase and morphological evolution of Ti₃SiC₂ was analyzed using X-ray diffraction (XRD) patterns, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). XRD results revealed that after 24?h HF treatment the diffraction peaks of Ti₃SiC₂ were fully disappeared and this treatment led to the decomposition of Ti₃SiC₂ to TiC. XRD and EDS findings demonstrated that de-intercalation of Si layer occurred after HF treatment. Moreover, SEM images showed that the morphological shape of TiC particles significantly changed as a function of HF treatment times. In summary, the shape of TiC particles changed from the polyhedron to hexagonal, then to truncated octahedron, octahedron and cubic.     

Ant Colony Optimization for Multi-Objective Multicast Routing

In the distributed networks, many applications send information from a source node to multiple destination nodes. To support these applications requirements, the paper presents a multi-objective algorithm based on ant colonies to construct a multicast tree for data transmission in a computer network. The proposed algorithm simultaneously optimizes total weight (cost, delay and hop) of the multicast tree. Experimental results prove the proposed algorithm outperforms a recently published Multi-objective Multicast Algorithm specially designed for solving the multicast routing problem. Also, it is able to find a better solution with fast convergence speed and high reliability.     

Revisiting the Diffusion of Niobium in an As-Cast Nickel-Based Superalloy During Annealing at Elevated Temperatures

Metals and Materials International - While understanding the interdiffusion of Nb in the austenite matrix of Ni-based superalloys is important for studying the precipitation reactions (Laves phase,...