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Nanoparticles (NPs) are promising candidates for different biomedical applications due to their excellent antimicrobial applications. However, the applications become limited due to the higher cost of NP synthesis. In his research work, Hydroxyapatite Nanoparticles (HANPs) have been synthesized in a cost-effective method to apply in biomedical applications. The synthesized HANPs have been characterized by different morphological and antimicrobial characterization methods. Ultraviolet–Visible (UV) spectroscopy was performed and a peak was obtained at 271nm which confirmed the formation of NPs and opened a new door for further analysis. Fourier Transformed Infrared Spectroscopy (FTIR) has been performed and the presence of functional groups such as hydroxides carbonates and phosphates have been identified. Transmission Electron Microscopy (TEM) analysis reveals the circular and smaller shape of the synthesized HANPs. The chemical elements of HA have been identified by EDS analysis. Sharp peaks identified by the X-Ray Diffraction (XRD) analysis confirm the formation of crystals in the synthesized HANPs. An excellent antimicrobial performance which is 99.99% has been obtained from the gram-positive and gram-negative bacterial strains. The obtained results suggest the potentiality of the synthesized HANPs in biomedical applications.

We build and investigate a nonstandard model of pattern formation in a system of discrete entities evolving in discrete space and time. We chose a sandpile paradigm to fit our ideas in the frame of current research. In our model sand is hot because a grain can topple against gradient, i.e., the grain can walk to another node even when a number of grains in its current node is less than a number of neighboring nodes. Sand is choosey because behavior of the grains is not determined by any global parameter or any threshold of a number of neighboring grains (called here a grain sensitivity) but depends on the exact number of grains in the neighboring nodes. Namely, we assume that a grain being at a node x goes to one of the eight neighboring nodes, chosen at random, if there is another grain at the node x or if the number of grains in eight neighboring nodes lies in some set of 2^{1,…,8}. These 256 rules of sensitivity are investigated. The classification of the rules if offered, based on the morphology of the patterns generated by each rule. Eight morphological classes are found. Fine structure of every class is investigated and transient phenomena are analyzed. Three kinds of description of class rules by Boolean expressions are offered. Evolution of the classes governed by several one-dimensional parameters is considered.

In this work, we investigate the influence of substrate temperature on the surface morphology for substrate coverage below one monolayer. The model of film growth is based on random deposition enriched by limited surface diffusion. Also, anisotropy in the growth is involved. We found from computer simulations for the simple cubic lattice and solid-on-solid model that the surface morphology changes with increasing temperature from isotropically distributed isolated small islands through anisotropic 1D stripes to larger 2D anisotropic islands and again randomly distributed single atoms. The transition is also marked in height–height correlation function dependence on temperature as directly seen by snapshots from simulations. The results are in good qualitative agreement with already published results of kinetic Monte Carlo simulations as well as with some experimental data.

A molecular simulation study of the mesoscale self-assembly of tethered nanoparticles having a cubic geometry is presented. Minimal models of the tethered nanocubes are developed to represent a polyhedral oligomeric silsesquioxane (POSS) molecule with polymeric substituents. The models incorporate some of the essential structural features and interaction specificity of POSS molecules, and facilitate access to the long length and timescales pertinent to the assembly process while foregoing atomistic detail. The types of self-assembled nanostructures formed by the tethered nanocubes in solution are explored via Brownian dynamics simulations using these minimal models. The influence of various parameters, including the conditions of the surrounding medium, the molecular weight and chemical composition of the tether functionalities, and the number of tethers on the nanocube, on the formation of specific structures is demonstrated. The role of cubic nanoparticle geometry on self-assembly is also assessed by comparing the types of structures formed by tethered nanocubes and by their flexible coil triblock copolymer and tethered nanosphere counterparts. Morphological phase diagrams are proposed to describe the behavior of the tethered nanocubes.

The random deposition model must be enhanced to reflect the variety of surface roughness due to some material characteristics of the film growing by vacuum deposition or sputtering. The essence of the computer simulation in this case is to account for possible surface migration of atoms just after the deposition, in connection with the binding energy between atoms (as the mechanism provoking the diffusion) and/or diffusion energy barrier. The interplay of these two factors leads to different morphologies of the growing surfaces, from flat and smooth ones to rough and spiky ones. In this paper, we extended our earlier calculation by applying an extra diffusion barrier at the edges of terrace-like structures, known as the Ehrlich–Schwoebel barrier. It is experimentally observed that atoms avoid descending when the terrace edge is approached, and these barriers mimic this tendency. Results of our Monte Carlo computer simulations are discussed in terms of surface roughness, and compared with other model calculations and some experiments from literature. The power law of the surface roughness σ against film thickness t was confirmed. The nonzero minimum value of the growth exponent β near 0.2 was obtained which is due to the limited range of the surface diffusion and the Ehrlich–Schwoebel barrier. Observations for different diffusion ranges are also discussed. The results are also confirimed with some deterministic growth models.

In this paper we present a generalization of a simple solid-on-solid epitaxial model of thin film growth, when surface morphology anisotropy is provoked by anisotropy in the model control parameters of binding energy and/or diffusion barrier. The anisotropy is discussed in terms of the height–height correlation function. It was experimentally confirmed that the difference in diffusion barriers yields anisotropy in morphology of the surface. We obtained antisymmetric correlations in the two in-plane directions for antisymmetric binding.

We studied the dependence of morphology and luminosity of the SDSS galaxies on the environmental factors. The environmental factors considered include the local density due to the nearest neighbor galaxy ρ_n, morphology of the nearest neighbor, and the large-scale background density. We found the local environment set up by the nearest neighbor galaxy gives strong effects on the galaxy morphology. The probability for a galaxy to have an early morphological type critically depends on whether or not ρ_n is above the virialization density. We conclude that the well-known morphology-density relation is basically due to the interactions between galaxy pairs. Dependence of galaxy morphology on the large-scale density is found only because there is a statistical correlation between the average pair separation and the large-scale background density. We also found that galaxy luminosity depends on ρ_n, and that, when the large-scale density is fixed, more isolated galaxies are more likely to be recent merger products. We propose a scenario that a series of morphology and luminosity transformation occur through a series of distant/close interactions and mergers, which results in the morphology-luminosity-local density relation.

La_2/3Ca_1/3MnO₃ (LCMO) thin films with the thickness from 4 nm to 50 nm were fabricated by the off-axis magnetron sputtering technique. Single crystal (001) SrTiO₃ (STO), (0001) sapphire (ALO), and (001) yttrium-stabilized ZrO₂ (YSZ) were used as substrates. The surface morphology of thin films was characterized by atomic force microscope (AFM). The surface morphology of the thin films depends on the thickness. Thin films on STO substrates with the thickness less than 20 nm show a wave-like morphology, which indicates a two-dimension growth mode. With the thickness increases, some cracks and grains appear on the surface, which indicates the release of the lattice strain due to the lattice mismatch between the substrate and the films. The morphology became smoother with the thickness more than 30 nm, which indicates the full relaxation in strain for the film. The surface roughness and the average grain size increase with the thickness. The morphology for LCMO grows on ALO and YSZ show a rougher surface than that on STO. The rough surface morphology may indicate the wide metallic-to-insulating transition in transport properties.

The surface morphology of low-energy deposited Pb cluster films was characterized by TEM observation. The free clusters before arrival on the substrates were considered as liquid droplets and a cooling time was assumed to interpret the final morphology by DDA (deposition-diffusion-aggregation) model. The island radius is related to the cluster beam flux, effective diffusion radius and the cooling time. There appeared a viscous net instead of neck-connections and islands when several layers were deposited. After as-prepared samples were exposed to air, an oxide coating, i.e. a core/shell structure, was formed and it could prevent the Pb core from full oxidation.

The high temperature property of SiC/SiC composites fabricated by the melt infiltration (MI) process has been investigated. SiC/SiC composites reinforced with BN/SiC double coated Hi-Nicalon SiC fibers were fabricated by infiltrating molten silicon into a braiding fibric preform containing C and SiC particles. The mechanical properties of MI-SiC/SiC composites were carried out at the elevated temperatures using the three point bending test. The microstructure of MI-SiC/SiC composites was examined by means of SEM and EDS. The matrix region of MI-SiC/SiC composites represented the chemical fluctuation depending on the composition ratio of Si and C elements. The flexural strength of MI-SiC/SiC composites greatly decreased at the temperatures higher than 1100 °C, due to microstructural instabilities such as interfacial debonding and matrix oxidation.

Nano-sized mullite was synthesized by mechano-chemical, sol-gel/milling, process. Aluminum nitrate and tetraethyl ortho silicate were used as precursors to prepare the single phase gel. The prepared gel was subjected to intense mechanical activation using a planetary ball mill prior to annealing. DTA/TGA results showed that mullitization temperature significantly decreases due to mechanical activation as mullite starts to form at 1094°C in unmilled sample whereas intermediate milling for 20 hours decreases this temperature to 988°C. Also, mullite formation occurs at 1021 and 1003°C for samples milled for 5 and 10 hours, respectively. SEM results showed that the morphology of the products was altered by the intermediate mechanical activation. Calculation of the mullite crystallite sizes indicated that they were indeed in nano scale and this result was confirmed by TEM investigations which shows the mean crystallite size of 70 nm.

Zn-Fe alloy electroplated coatings have attracted industrial interest because of their significantly higher corrosion resistance in comparison to pure zinc deposits. In this study pulse currents was applied for electrodeposition of Zn-Fe alloys, using alkaline bath. SEM studies confirmed that pulse electrodeposits are quite dense and smooth. It was also shown that increasing of peak current density (PCD) and duty cycle in pulse electrodeposition coarsen the structure and increase irregularity of the surface. Increasing of the frequency, on the other hand, results in the formation of finer structure.

Titanium dioxide nanoparticles were prepared by precipitation of aqueous TiCl₄ solution with ammonium hydroxide as precipitation agent. Freshly prepared Titania gel is allowed to crystallize under refluxing and stirring condition for 6 h over 90°C and oven dried over night in temperature above 100 C. X-ray diffraction studies on oven dried powder indicate formation of anatase phase TiO₂ with average crystalline size of 4.5 nm. Powders with variable amount of anatase and rutile phase were prepared by calcination of pure anatase in the temperature range 400-1000 c for 4 h. the XRD patterns show that phase transition from anatase to rutile occur in calcination above 600°C. The morphology and microstructure characteristics were obtained by XRD, TEM. and TGA.

This paper presents recent studies on the processing and characterization of epoxy-alumina nanocomposites. Nano-sized alumina particles are incorporated into epoxy resin via solvent-assisted method, so that the particles are dispersed homogeneously in the epoxy matrix. The morphologies, mechanical and thermomechanical properties of the resulting nanocomposites are studied using transmission electron microscope (TEM), conventional tensile testing and thermomechanical testing methods. TEM results show that the alumina nano-particles with a higher specific surface area tend to agglomerate. Furthermore platelet shape particles shows a better dispersion homogeneity as well as better improvement in the mechanical properties of the composites compared to the rod shape particles.

β-NiAl as a promising oxidation resistant coating material due to it high melting point and good oxidation resistant, however it reveals poor cyclic oxidation performance. In this paper, reactive element Dy doped β-NiAl coatings were prepared by electron beam physical vapor deposition (EB-PVD). Dy doping led to the grain refinement microstructure and Dy segregated mainly at grain boundaries. Cyclic oxidation behaviors of the coatings at 1100°C were investigated. The 0.05at.% Dy and 0.1at.% Dy doped coatings exhibited lower oxidation rate and better cyclic oxidation performance, as compared to the undoped coating. The effects of Dy addition on the morphologies and growth mechanism of the oxide scale were discussed.

Cerium oxides (CeO₂) were synthesized by two steps solvothermal routes. First, a precursor was precipitated using solutions of cerium (III) nitrate and ammonia, and then this precursor was treated via solvothermal techniques in an autoclave. Narrow distribution of CeO₂ particle size, between 10 to 15 nm, was achieved in different solvents. Hard agglomerates of nano-CeO₂ were mitigated in an ethanol solvent. Most of crystal particles were in the shape of a quadrangle for the precursor. Morphology of CeO₂ particles gradually changed after the precursor was treated by solvothermal techniques. There were both quadrangular and symmetrically hexagonal particles at an alkaline pH value. Alternatively, the quadrangular particles disappeared, instead of geometrically unsymmetrical hexagon with decreasing pH to a more acid value. The evolution mechanism of the morphology was discussed. These results have important implications for recognizing and controlling the crystalline shape by solvothermal techniques.

Different treatment time and bias voltage with RF Ar plasma were used to improve tribological properties of NBR (Nitrile Butadiene Rubber). Chemical structure analyses of NBR by Attenuated Total Reflectance (ATR) were performed to clarify the functionality modification after the plasma treatment. In addition, wetting experiments were carried out by measuring the contact angle of distilled water drops on the NBR surface. ATR analysis revealed that the number of -C=O, -C-O, O-H functional groups increased after the argon plasma treatment. The functional groups led to changes in the contact angle from 100 to 50 degrees. The results showed that form-like nanostructures on the NBR was observed at the bias voltage of -400 V. The friction test showed that coefficient of friction after modified NBR in lubricated condition decreased from 0.25 to 0.15 with the increasing bias voltage due to the surface structure formations and better bonding with grease lubricant.

A sol-gel method is investigated to synthesize CuO–ZrO₂ nanoparticles as catalyst for hydrogen production from methanol. Finer precursor nanoparticles give rise to larger specific areas in catalyst which result in a high hydrogen production. The effects of some critical process parameters on the sol-gel synthesis of CuO–ZrO₂ nanoparticles are studied. These parameters are affected on synthesis of CuO–ZrO₂ when it is prepared with sol-gel method. Particle size and distribution are considered as the results. The parameters including the effect of calcination temperature, aging temperature, nature and concentration of catalyst (acidic or basic conditions), H₂O/precursor molar ratio, and chelating agent that have been identified as most important, are focused. It is found that the calcination temperature strongly influenced the morphology and interaction between the active species and support, and hence the structure and catalytic performance. Nature and concentration of catalyst (pH value), chelating agent, (H₂O/precursor) molar ratio and also aging temperature have influence on the nanoparticles. Thus, by controlling these factors, it is possible to vary the morphology and properties of the sol-gel-derived inorganic network over wide ranges. Morphology, particle size and distribution, phase evaluation, structure, and chemical analysis of the products are investigated by SEM, TEM, DTA/TG, XRD and EDX respectively.

Molecular dynamics (MDs) simulations were used to explore the thermal stability of Au nanoparticles (NPs) with decahedral, cuboctahedral, icosahedral and Marks NPs. According to the calculated cohesive energy and melting temperature, the Marks NPs have a higher cohesive energy and melting temperature compared to these other shapes. The Lindemann index, radial distribution function, deformation parameters, mean square displacement and self-diffusivity have been used to characterize the structure variation during heating. This work may inspire researchers to prepare Marks NPs and apply them in different fields.

Cobalt (Co) doped magnesium hydroxide Mg(OH)₂ nanoparticles are synthesized by a surfactant-free co-participation method. Scanning electron microscopy (SEM) images show nanometer size Mg(OH)₂ particles in spherically shaped particle-like morphology. Synthesis of these Mg(OH)₂ nanocrystals involves the formation of monomeric MgOH${}^{+}$ ions as the precursor for the Mg(OH)₂ nuclei which finally evolves in spherical particle-like morphology. X-ray diffraction (XRD) confirms the hexagonal crystal structure of the samples. With increasing Co concentration, the absorption spectra of the samples show narrowing of the bandgap from 5.47 eV (for pure Mg(OH₂)) to 5.26 eV (for 10% Co-doped Mg(OH₂)) effect is attributed to changes in the interaction potentials between Co and the host Mg(OH)₂ lattice due to dopant-induced lattice distortion and the presence of a mixed valance Co${}^{2+}$/Co${}^{3+}$ state.