Iranian Journal of Materials Science and Engineering

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Hydration behavior and antioxidising effect of aluminium (AI) powder has been investigated. Bayerite Al (OH) 3 product layers formed on Al in pure water at 25-45°C were porous, so the hydration rate, although very slow at 25°C, increased rapidly with increasing temperature from 25 to 45°C. On further increasing temperature from 45 to 95°C, initial hydration rate increased, but changed little over long hydration periods due to formation of denser and more continuous product layers. At 100?C, due to rapid water-evaporation, hydration product layers (composed of Al (OH)3 and a small amount of boehmite AlO (OH) became detached from the Al surfaces, so offering less protection, so that the hydration rate of Al increased markedly. The presence of MgO or calcium aluminate cement (CAC) in water did not change the hydration product, but greatly accelerate the hydration rate of AI. Addition of even a small amount (e.g. 0.25 wt% of Al amount) of MgO or CAC to water accelerated significantly the hydration of Al, and with increasing level of MgO or CAC, the hydration extent increased markedly. Sol-gel Si02 coatings on Al were useful in improving the hydration resistance of Al, and did not have a negative effect on the behavior of Al as an antioxidant.

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Abstract:In recent years, there have been many attempts to improve the properties of dental amalgam. The aim of the present investigation was fabrication and characterization of dental amalgams containing TiO2 nanoparticles and evaluation of their compressive strength, antibacterial and corrosion behavior. In this experimental research, TiO2 nanoparticles (TiO2 NPs) were added to reference amalgam alloy powder and then, dental amalgam was prepared. In order to investigate the effect of TiO2 NPs on properties of dental amalgam, 0, 0.5, 1, 2 and 3 wt. % of TiO2 NPs were added to amalgam alloy powder and the prepared composite powder was triturated by a given percent of mercury. Xray diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy-Dispersive Spectroscopy (EDS) techniques were used to characterize the prepared specimens. Potentiodynamic polarization corrosion tests were performed in the Normal Saline (0.9 wt. % NaCl) Solutions as electrolytes at 37°C. The results showed that the corrosion behavior of the dental amalgam with 0.5 or 1 wt. % TiO2 NPs is similar to the corrosion behavior of the reference amalgam, while with increasing the weight percent of TiO2 NPs, the corrosion rate increases. Also, the results of this investigation indicated that adding TiO2 NPs in amounts of up to 1 wt. % to amalgam alloy powder improve compressive strength of dental amalgam and has no destructive influence on its corrosion behavior. As well as, according to antibacterial results, TiO2 NPs can increase the biocompatibility and antibacterial activity of dental amalgam. The results of present study suggest that amalgam/ TiO2 NPs nanocomposite with 1% of TiO2 NPs could be regarded as a biocompatible and bioactive dental material that provide better characters for dental applications.

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The inherent reactivity of the Al–Cu alloys is such that their use for structural, marine, and aerospace components and structures would not be possible without prior application of a corrosion resistance system. Historically these corrosion resistance coatings were based on the use of chemicals containing Cr (VI) compounds. Silane coatings are of increasing interest in industry due to their potential application for the replacement of current toxic hexavalent chromate based treatments. In this study, hydrophobic coating sol was prepared with methyltriethoxysilane (MTES), methanol (MeOH), and water (as 7M NH4OH) at a molar ratio of 1:25:4.31 respectively. The coatings were applied by a dip-technique to 2024-T3 Al alloy, and subsequently cured at room temperature and there after heat treated in an oven at 150°C. The anticorrosion properties of the coatings within 3.5 wt% NaCl solution were studied by Tafel polarization technique. The sol–gel coating exhibited good anticorrosion properties providing an adherent protection film on the Al 2024-T3 substrate. The surface properties were characterized by water contact angle measurement, scanning electron microscopy (SEM), and the composition was studied by Fourier transform infrared spectroscopy (FTIR).

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The inhibition performances of nafcillin (III), methicillin (II) and penicillin G (I) on the corrosion of copper in HCl was studied and tested by weight loss, Tafel polarization, SEM, UV-vis spectrophotometry, molecular dynamics method and quantum chemical calculations. Polarization curves indicated that the studied inhibitors act as mixed-type inhibitors. The values of inhibition efficiency and surface coverage were found to follow the order: Blank ads, indicated that the adsorption of three inhibitors was a spontaneous process. The SEM micrographs confirmed the protection of copper in a 1 M HCl solution by penicillin G, nafcillin, and methicillin. The shape of the UV/vis spectra of inhibitors in the presence of the immersion of Cu showed a strong support to the possibility of the chemisorbed layer formation on Cu surface by nafcillin (between nafcillin and Copper) and physisorption between penicillin and methicillin with copper. DFT calculations were performed to provide further insight into the inhibition efficiencies which were determined experimentally. Molecular dynamics (MD) simulations were applied to find the most stable configuration and adsorption energies of penicillin G, nafcillin and methicillin molecules on Cu (110) surface. The interaction energy followed the order: nafcillin (III)> methicillin (II)> penicillin G (I), which confirmed that nafcillin has the strongest interaction with the metal surface. The obtained results from experimental and theoretical methods were in reasonable agreement.
 

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This study focuses on the physical, magnetic, biological and antibacterial behaviour of cobalt-doped HAp powder samples. Pure and Cobalt- doped HAp nanoparticles were synthesized by hydrothermal method. Calcium nitrate, di- ammonium hydrogen phosphate and cobalt nitrate were used as precursor materials.  The synthesized powders were characterized using x-ray diffraction pattern (XRD), fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), vibrating sample magnetometer (VSM), Raman spectroscopy as well as MTT assay and cell adhesion test. Disc diffusion method was used to investigate antibacterial activity of the samples. The results confirmed the substitution of Ca by Co ions in the HAp lattice. In addition, this substitution induced size reduction and morphology change in HAp particles. All cobalt substituted HAp powder samples displayed paramagnetic properties, as opposed to the diamagnetic behaviour observed in the pure HAp samples. In addition, these nanoparticles exhibited cell adhesion, biocompatibility and antibacterial activity against S.aureus bacteria.
This study focuses on the physical, magnetic, biological and antibacterial behaviour of cobalt-doped HAp powder samples. Pure and Cobalt- doped HAp nanoparticles were synthesized by hydrothermal method. Calcium nitrate, di- ammonium hydrogen phosphate and cobalt nitrate were used as precursor materials.  The synthesized powders were characterized using x-ray diffraction pattern (XRD), fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), vibrating sample magnetometer (VSM), Raman spectroscopy as well as MTT assay and cell adhesion test. Disc diffusion method was used to investigate antibacterial activity of the samples. The results confirmed the substitution of Ca by Co ions in the HAp lattice. In addition, this substitution induced size reduction and morphology change in HAp particles. All cobalt substituted HAp powder samples displayed paramagnetic properties, as opposed to the diamagnetic behaviour observed in the pure HAp samples. In addition, these nanoparticles exhibited cell adhesion, biocompatibility and antibacterial activity against S.aureus bacteria.

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In the research, Titanium dioxide/Graphene Oxide thin films at different concentration of graphene oxide (0.0, 0.015, 0.030, 0.045 and 4.5 g/ml) were prepared by spin coating method. Characterization of the samples was performed using X-ray diffraction and Field Emission Scannig Eelectron Microscope and Atomic Force Microscope. X-ray diffraction results show that by adding the graphene oxide, the peak associated with (001) reflection is observed at the angle of 10.5°. The analysis of Eenergy Dispersive X-ray also confirms the formation of graphene oxide sheets. Considering the excellent photo catalytic and antibacterial properties of titanium dioxide, the effect of adding the different concentration of graphene oxide on these properties has been investigated. The results show that the presence of graphene oxide increases the inhibition of Escherichia coli bacterial growth.
 

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The Nano Hydroxyapatite (HAp), HAp/PEG and HAp/PVP powders derived from both Gastropod shell (natural source) and chemical precursor by the precipitation method were characterized through various characterization techniques such as FT-IR, XRD, SEM-EDX, TEM, Antibacterial activity and SBF analysis. Based on the structural, chemical, morphological and biological characteristics, HAp/PVP from natural and chemical precursors have been compared successfully. Calculated structural parameters, crystallinity index, C/P ratio, morphology, antibacterial activity and SBF analysis of the products show that HAp/PVP-S (derived from a natural source) exhibits good mechanical property, rod like morphology, good antibacterial activity and apatite formation ability at 14 days. EDX analysis also shows the presence of carbon and sodium in HAp/PVP-S. Comparative analysis reveals that characteristics of HAp/PVP-S such as high carbonate content, low crystallite size, poor crystalline nature, presence of trace metal, non-stoichiometric elemental composition and rod like crystals which are matched with the characteristics of biological apatite. Thus, the HAp/PVP-S has the ability to form bone apatite.

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Green synthesis refers to the synthesis of nanoparticles using plants and microorganisms. It is preferred over conventional methods as its sustainable, eco-friendly, cost effective and rapid method. The phytochemicals and enzymes present in plants and microorganisms respectively acts as the reducing and capping agent for the synthesis of nanoparticles. Phytochemicals and enzymes have the ability to reduce precursor metal ions into nanoparticles. As the conventional methods involve the use of high energy and toxic chemicals which are harmful to both environment and organisms, these synthesis methods are discouraged. Of the nanoparticles, gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) have gained lots of attention owing to their multiple applications and less toxicity. In addition, various in-vitro studies have reported the antimicrobial activity of AgNPs and AuNPs against various microbes. This particular review portrays the methods of nanoparticles synthesis, components of green synthesis, mechanism of green synthesis, antimicrobial activity, other applications and various factors affecting the green synthesis of AgNPs and AuNPs.

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Neoplastic cells have co-opted inflammatory receptors and signaling molecules that potentiate inflammation. Activated inflammatory pathways lead to neo-angiogenesis, lymph-angiogenesis, immunosuppression, tumor growth, proliferation and metastasis. This cancer-sustaining inflammation is a critical target to arrest cancer growth. Multiple drug resistance, high cost, low oral bioavailability and serious side effects have rendered conventional cytotoxic chemotherapeutics less impressive. The aim of this research was to achieve cancer debulking and proliferation prevention by limiting ‘cancer-sustaining’ tumor niche inflammation through non-conventional oral approach employing anti-inflammatory agents and avoiding conventional cytotoxic agents. Synergistic anti-inflammatory agents, i.e. celecoxib as selective COX-2 inhibitor and montelukast as cysteinyl leukotriene receptor antagonist, were selected. Silver nanoparticles (AgNPs) were used as nanocarriers because of their efficient synergistic anti-neoplastic effects and excellent oral drug delivery potential. Specifically, selected drugs were co-conjugated onto AgNPs. Synthesized nanoparticles were then surface-modified with poly(vinyl alcohol) to control particle size, avoid opsonization/preferred cellular uptake and improve dispersion. Surface plasmon resonance analysis, particle size analysis, DSC, TGA, XRD, FTIR and LIBS analysis confirmed the successful conjugation of drugs and efficient polymer coating with high loading efficiency. In-vitro, the nanoparticles manifested best and sustained release in moderately acidic (pH 4.5) milieu enabling passive tumor targeting potential. In-vivo, synthesized nanoparticles exhibited efficient dose-dependent anti-inflammatory activity reducing the dose up to 25-fold. The formulation also manifested hemo-compatibility, potent anti-denaturation activity and dose-dependent in-vitro and in-vivo anti-cancer potential against MCF-7 breast cancer and Hep-G2 liver cancer cell lines in both orthotopic and subcutaneous xenograft cancer models. The anti-inflammatory nanoparticles manifested tumor specific release potential exhibiting selective cytotoxicity at cancerous milieu with slightly acidic environment and activated inflammatory pathways. The formulation displayed impressive oral bioavailability, sustained release, negligible cytotoxicity against THLE-2 normal human hepatocytes, low toxicity (high LD₅₀) and wide therapeutic window. Results suggest promise of developed nanomaterials as hemo-compatible, potent, cheaper, less-toxic oral anti-inflammatory and non-conventional anti-cancer agents.

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Quaternary ammonium compounds (QACs) are among the most commonly used antibacterial agents. The aim of this study was to synthesize a dimethacrylate monomer functionalized with a QAC and to study its effect on the properties of an orthodontic adhesive primer. Urethane dimethacrylate monomer functionalized with a QAC (UDMAQAC) was synthesized and then characterized by nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infrared spectroscopy (FTIR). 5, 10, 15 and 20 wt% of UDMAQAC was added to an orthodontic adhesive primer (control group). FTIR analysis was used to measure the degree of conversion (DC). The bond strength of dental brackets was measured by shear bond strength (SBS) test and adhesive remaining index (ARI) was evaluated by stereomicroscope. Agar diffusion test and MTT assay were used to evaluate the antibacterial property and cell viability, respectively. Statistical analysis included one-way ANOVA with Tukey’s post hoc test and Kruskal-Wallis nonparametric test (P˂0.05). Although the obtained data did not show significant differences between the SBS and DC of different groups, but the highest values were obtained by adding 10 wt% monomer. Adding more than 10 wt% UDMAQAC resulted in significant increase in antibacterial property. The 15 and 20 wt% groups showed significantly lower cell viability

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The principal goal of this research is to produce a CrN/Cu multilayer coating and a CrN single-layer
coating and also compare their electrochemical and antibacterial behavior. In this investigation, the coatings were
applied to the stainless steel substrate by cathodic arc evaporation a sub-division of physical vapor deposition
(CAE-PVD). The present phases were characterized and the thickness of the coatings was measured using X-ray
diffraction (XRD) and field emission scanning electron microscopy (FE-SEM), respectively. Rockwell-C tester was
used to evaluate the adhesion quality. Also, to evaluate the mechanical properties of the coatings such as modulus
of elasticity and hardness, a nanoindentation test was used and the indentation effect and coating topography were
evaluated using atomic force microscopy (AFM). Studying the electrochemical behavior of the coatings was done
using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) tests in Ringer's
solution. The results of EIS tests showed that the CrN coating had higher polarization resistance in comparison to
the CrN/Cu coating and an increasing trend of polarization resistance related to both coatings was identified by
rising the time of immersion. Also, using the PDP curves, the CrN and CrN/Cu coating current densities were
estimated at 1.835×10-8 and 2.088×10-8, respectively. The antibacterial activity of CrN and CrN/Cu coatings was
evaluated by the spot-inoculation method. The results of the antibacterial test indicated that compared to CrN
coating, CrN/Cu coating had a better impact on the control of the bacteria growth.

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Drug-resistance among bacteria is a concerning issue in medical field. Silver nanoparticles (AgNPs) are one of the promising novel nano-antibiotics. In the present study, AgNPs were synthesized using cell-free extract of Acinetobacter sp. challenged with silver nitrate. Preliminary observations done using UV-Vis spectrophotometry at 420 nm. Complete reduction of silver ions to AgNPs was confirmed through cyclic voltammetry. Electron microscopy revealed formation of spherical shaped nanoparticles of size upto 20 nm. These AgNPs were furthr used to determine their effect on activity of various antibiotics against pathogenic bacteria such as Neisseria and Xanthomonas. Higher antibacterial activity of AgNPs was observed against Gram-negative bacteria. Enhanced antibacterial action of AgNPs was observed with selected beta-lactam antibiotics producing upto 3-fold increase in area of zone of inhibition. On exposure to AgNPs, the minimum inhibitory concentration and minimum bactericidal concentration of antibiotics were lowered by upto 2000 times indicating potential synergistic action of AgNPs. This study clearly signifies that the drug, proved to be inefficient due to bacterial resistance, could be made functional again in presence of AgNPs. This will help in development of novel antibacterial formulations containing antibiotics and nanoparticles to combat multiple drug-resistance in microorganisms.

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Researchers are increasingly focusing on green synthesis methods for silver nanoparticles due to their cost-effectiveness and reduced environmental impact. In this study, we utilized an edible bird's nest (EBN), a valuable economic resource, as the primary material for synthesizing silver nanoparticles using only water as the solvent. Metabolite profiling of the EBN extract was conducted using LC-QTOF-MS in positive mode (ESI+), revealing the presence of lipids, glycosides, peptides, polysaccharides, and disaccharides. Upon the addition of silver nitrate to the aqueous EBN extract, noticeable color changes from transparent to brown indicated the successful formation of AgNPs. Subsequent characterization of these silver nanoparticles involved UV-Visible spectroscopy, which revealed an absorption peak at 421 nm. Further characterization was carried out using FESEM, ATR-FTIR spectroscopy, and EDX analysis. The involvement of phenolic agents, proteins, and amino acids in reducing the silver particles was confirmed. The synthesized nanoparticles exhibited a spherical shape, and a particle size ranging from 10 to 20 nm. The presence of elemental silver was confirmed by a strong, intense peak around 3 keV in the EDX spectrum. To assess their potential, the antibacterial properties of the silver nanoparticles against Escherichia coli and Staphylococcus aureus were evaluated using the agar diffusion method.
 

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Silver/polyvinyl alcohol (Ag/PVA) nanocomposites were fabricated via an electrochemical method. Silver nanoparticles (AgNPs) with varying grain sizes were directly synthesized within PVA polymer matrices at deposition times of 15, 30, 45, 60, and 120 minutes. The integration of AgNPs within the PVA matrix was confirmed through Transmission Electron Microscopy (TEM) and optical absorbance measurements. X-ray Diffraction (XRD) analysis demonstrated the face-centered cubic structure of AgNPs. Furthermore, these prepared nanocomposites exhibited significant antibacterial properties against Bacillus subtilis and Pseudomonas pneumonia, as well as antifungal activity against Alternaria alternata. Remarkably, the AgNPs/PVA nanocomposite exhibited outstanding antifungal efficiency, resulting in an impressive inhibition zone of up to 47 mm.
 

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