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Papers by BOGDAN NICOLAE VASILE

Materials, 2021

In this study, zinc oxide nanoparticles were synthesized through a simple co-precipitation method... more In this study, zinc oxide nanoparticles were synthesized through a simple co-precipitation method starting from zinc acetate dihydrate and sodium hydroxide as reactants. The as-obtained ZnO nanoparticles were morphologically and structurally characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photocatalytic activity, and by determining the antimicrobial activity against Gram-negative and Gram-positive bacteria. The XRD pattern of the zinc oxide nanoparticles showed the wurtzite hexagonal structure, and its purity highlighted that the crystallinity correlated with the presence of a single product, zinc oxide. The ZnO nanoparticles have an average crystallite size of 19 ± 11 nm, which is in accordance with the microscopic data. ZnO nanoparticles were tested against methyl orange, used as a model pollutant, and it was found that they exhibit strong photocatalytic activity a...

Antibiotics, 2021

Recent years have witnessed a tremendous interest in the use of essential oils in biomedical appl... more Recent years have witnessed a tremendous interest in the use of essential oils in biomedical applications due to their intrinsic antimicrobial, antioxidant, and anticancer properties. However, their low aqueous solubility and high volatility compromise their maximum potential, thus requiring the development of efficient supports for their delivery. Hence, this manuscript focuses on developing nanostructured systems based on Fe3O4@SiO2 core–shell nanoparticles and three different types of essential oils, i.e., thyme, rosemary, and basil, to overcome these limitations. Specifically, this work represents a comparative study between co-precipitation and microwave-assisted hydrothermal methods for the synthesis of Fe3O4@SiO2 core–shell nanoparticles. All magnetic samples were characterized by X-ray diffraction (XRD), gas chromatography-mass spectrometry (GC-MS), Fourier-transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), zeta potential, scanning electron microscopy (S...

International Journal of Molecular Sciences, 2021

The development of drug-resistant microorganisms has become a critical issue for modern medicine ... more The development of drug-resistant microorganisms has become a critical issue for modern medicine and drug discovery and development with severe socio-economic and ecological implications. Since standard and conventional treatment options are generally inefficient, leading to infection persistence and spreading, novel strategies are fundamentally necessary in order to avoid serious global health problems. In this regard, both metal and metal oxide nanoparticles (NPs) demonstrated increased effectiveness as nanobiocides due to intrinsic antimicrobial properties and as nanocarriers for antimicrobial drugs. Among them, gold, silver, copper, zinc oxide, titanium oxide, magnesium oxide, and iron oxide NPs are the most preferred, owing to their proven antimicrobial mechanisms and bio/cytocompatibility. Furthermore, inorganic NPs can be incorporated or attached to organic/inorganic films, thus broadening their application within implant or catheter coatings and wound dressings. In this cont...

Nanomaterials, 2020

The present article evaluates, in qualitative and quantitative manners, the characteristics (i.e.... more The present article evaluates, in qualitative and quantitative manners, the characteristics (i.e., thickness of layers, crystal structures, growth orientation, elemental diffusion depths, edge, and screw dislocation densities), within two GaN/AlN/Si heterostructures, that alter their efficiencies as positron moderators. The structure of the GaN film, AlN buffer layer, substrate, and their growth relationships were determined through high-resolution transmission electron microscopy (HR-TEM). Data resulting from high-resolution X-ray diffraction (HR-XRD) was mathematically modeled to extract dislocation densities and correlation lengths in the GaN film. Positron depth profiling was evaluated through an experimental Doppler broadening spectroscopy (DBS) study, in order to quantify the effective positron diffusion length. The differences in values for both edge ( ρ d e ) and screw ( ρ d s ) dislocation densities, and correlation lengths (Le, Ls) found in the 690 nm GaN film, were associ...

International Journal of Pharmaceutics, 2017

The increasing rate of antibiotic resistant bacteria associated with nosocomial infections in sev... more The increasing rate of antibiotic resistant bacteria associated with nosocomial infections in severely ill patients has urged the need for new antibacterial therapies. Nanostructured materials represent emerging innovative approaches to controlled delivery of different antimicrobial drugs. Delivery systems encapsulating natural compounds with antibacterial effects, such as essential oils have shown a great potential. Herein we report the development of SiO2 mesoporous nanosystems loaded with eucalyptus (EUC), orange (ORA), and cinnamon (CIN) essential oils. These systems were characterized with respect to morphology (using scanning electron microscopy, SEM, and transmission electron microscopy, TEM), porosity (by BET and TEM analysis), chemical composition (by X-ray diffraction, XRD, and Fourier transform infrared spectrometry, FTIR) and loading capacity (by thermogravimetric analysis, TGA). The anti-bacterial and anti-adherence effects were tested against clinically relevant microbial species (Staphylococcus aureus ATCC 25923; Escherichia coli ATCC 25922; and Candida albicans ATCC 10231), while the biocompatibility was evaluated by in vitro tests with L929 mouse fibroblast cells.

Metals, 2016

The aim of this study was to develop a biocompatible coating for wound dressings, containing iron... more The aim of this study was to develop a biocompatible coating for wound dressings, containing iron oxide nanoparticles functionalized with patchouli essential oil in order to obtain improved antimicrobial properties able to prevent biofilm development and consecutive associated infections. The bioactive coating was prepared by the co-precipitation of a precursor in an alkaline solution of patchouli oil. The prepared surface was characterized by XRD (X ray diffraction), TEM (transmission electron microscopy), SAED (selected area diffraction), SEM (scanning electron microscopy) and FT-IR (Fourier transform infrared spectroscopy). The bioevaluation of the obtained coating consisted in antimicrobial, as well as in vitro and in vivo biocompatibility and biodistribution assays. The obtained coating revealed a strong anti-biofilm activity maintained up to 72 h, as well as a low cytotoxicity on mammalian cells and a good biodistribution after intraperitoneal injection in mice. These results demonstrate the promising potential of the respective coatings for the management of wound infections and for the development of soft materials with improved resistance to microbial colonization.

Applied Surface Science, 2016

In this study, we investigated the potential of MAPLE-deposited coatings mesoporous silica nanopa... more In this study, we investigated the potential of MAPLE-deposited coatings mesoporous silica nanoparticles (MSNs) to release Zinforo (ceftarolinum fosmil) in biologically active form. The MSNs were prepared by using a classic procedure with cetyltrimethylammonium bromide as sacrificial template and tetraethylorthosilicate as the monomer. The Brunauer-Emmett-Teller (BET) and transmission electron microscopy (TEM) analyses revealed network-forming granules with diameters under 100 nm and an average pore diameter of 2.33 nm. The deposited films were characterized by SEM, TEM, XRD and IR. Microbiological analyses performed on ceftaroline-loaded films demonstrated that the antibiotic was released in an active form, decreasing the microbial adherence rate and colonization of the surface. Moreover, the in vitro and in vivo assays proved the excellent biodistribution and biocompatibility of the prepared systems. Our results suggest that the obtained bioactive coatings possess a significant potential for the design of drug delivery systems and antibacterial medical-use surfaces, with great applications in bone implantology.

S-a eleborat un procedeu eficient şi nepoluant de sinteză a argintului macroporos granular prin r... more S-a eleborat un procedeu eficient şi nepoluant de sinteză a argintului macroporos granular prin reducerea Ag 2 SO 4 cu acid ascorbic, în fază heterogenă în mediu apos. Procedeul elaborat este cumparat cu procedee similare realizate prin reducerea cu acid ascorbic a AgNO 3 , şi respectiv a AgNO. Probele au fost examinate la microscopul optic şi caracterizate prin analiză XRD. Au fost estimate porozitatea şi proprietăţile lor electroconductive. Argintul granular microporos obtinut a fost caracterizat prin analiză FTIR, TG-DSC, TEM şi testat drept catod într-o celulă de electroliză în soluţie de KOH comparativ cu un catod din argint masiv. Conductivitatea electrică bună şi suprafaţa specifică mare a produsului ar putea permite utilizarea acestuia în electrochimie. An effective and green route was elaborated for synthesis of macroporous granular silver by reduction of Ag 2 SO 4 with ascorbic acid in heterogeneous phase in aqueous medium. The synthesis method was compared with similar procedures using the reduction of AgNO 3 or AgNO 2 with ascorbic acid. The samples were examined by optical microscopy, XRD patterns as well as porosity and electroconductive properties.The product was characterized by FTIR, TG-DSC, TEM and tested as cathode in an electrolysis cell in KOH solution comparative to a bulk silver cathode. The good electric conductivity and high specific aria of the product may sustain its electrochemical use.

Digest Journal of Nanomaterials and Biostructures

Recently, the fabrication of shape controlled magnetite nanostructure was published by Zheng et a... more Recently, the fabrication of shape controlled magnetite nanostructure was published by Zheng et al. [16]. They concluded that magnetite shape can be controlled by precursor's concentrations and molecular weight of the polyethylene glycol which is used as dispersant. They found that cubic magnetite is obtained if 0.2M Fe 3+ , 0.1M Fe 2+ and 10-3 mol/L PEG (M.W.=20.000) solutions are used; nanorods with geometrical characteristics of 10nm x 100-200nm are obtained if solutions of 2.0x10-2 Fe 3+ , 1.0x10-2 Fe 2+ and 10-3 mol/L PEG (M.W.=20.000) are used and dendrides are obtained if solutions of 2.0x10-3 Fe 3+ , 1.0x10-3 Fe 2+ and 2.0x10-3 mol/L PEG (M.W.=20.000) are used. Also, the molecular weight of PEG leads to morphological changes of , A. FICAI, B.

MATERIALE PLASTICE

Bimetallic Pd-Ag nanoparticles (NPs) were obtained by polyol method in the presence of poly (viny... more Bimetallic Pd-Ag nanoparticles (NPs) were obtained by polyol method in the presence of poly (vinylpyrrolidone), PVP, as capping agent. The reduction of silver and palladium precursors was performed in argon inert atmosphere by successive reduction, or coreduction approach. In the successive reduction, AgNO 3 solution was injected in the ethylene glycol solution of PVP at 140°C, followed by the injection of [Pd(NH 3) 4 ]Cl 2 solution. The obtained bimetallic Pd-Ag NPs exhibited cluster structure, with the surface reach in silver. The NPs size was in the range of 30-58.5 nm with the average dimention of 41.5 nm. The coreduction approach consists in the hot injection of both metal precursors as complex ammine dissolved in ethylene glycol. By this method, smaller Pd-Ag NPs with the average sizes in the range 16-30 nm were obtained, depending on the synthesis parameters. The influence of metal cations : PVP molar ratio, metal cations concentration, Ag : Pd atomic ratio and the reduction temperature on the composition and morphology of the bimetallic NPs was studied. For both reduction approaches, based on the experimental data, two different reduction patways were proposed.

Revista Romana de materiale = Romanian journal of materials = RRM

ABSTRACT

Export Date: 29 April 2015, CODEN: SBPSF, References: Weißenrieder, K.S., Muller, J., Conductivit... more Export Date: 29 April 2015, CODEN: SBPSF, References: Weißenrieder, K.S., Muller, J., Conductivity model for sputtered ZnO-thin film gas sensors (1997) Thin Solid Films, 300 (1-2), pp. 30-41. , May;

Metalurgia international

Nanopowders based on Co-doped TiO2 anatase with homogeneous distribution of doping element were o... more Nanopowders based on Co-doped TiO2 anatase with homogeneous distribution of doping element were obtained by a hydrothermal process using KOH as mineralizing agent. The microstructure analysis made by RXD and SEM show the formation of nanopowders with single phase anatase structure. The stability and phase evolution of crystallized TiO2 during thermal treatment vs. Co content was studied using DSC-TG methods. The estimation of activation energy for hydrothermal crystallization was done based on XRD measurement of nanopowders obtained at different temperatures and times based on Avrami approach. The results show that Co - doped anatase nanopowders obtained by the proposed hydrothermal procedure show a good stability for potential applications in photo-catalytic processes and diluted magnetic semiconductors:

Revista Romana de materiale = Romanian journal of materials = RRM

The purpose of this study is to obtain nanometric zirconia powders, by sol-gel method, using prec... more The purpose of this study is to obtain nanometric zirconia powders, by sol-gel method, using precursors of different chemical nature - inorganic (ZrCl4) and organic (C12H28O4Zr). The obtained gels were dried at 100 degrees C, and then heat treated to 1000 degrees C for 2 hours. In order to identify obtained phases and their degree of crystallinity, powders were analyzed using X-ray diffraction. Analyses of scanning electron microscopy and transmission electron microscopy have been used to investigate the morphology and size of the obtained powders. Experimental analyzes show that, from different precursors (organic and inorganic), nanometric powders of partially stabilized zirconia with CaO are obtained.

Journal of Optoelectronics and Advanced Materials

The attractive properties of zirconia, particularly fracture toughness, wear resistance and chemi... more The attractive properties of zirconia, particularly fracture toughness, wear resistance and chemical stability, have led to vast research efforts designed to investigate, characterize and develop such materials. Applications vary from structural, mechanical, biomedical to electrical, especially the fuel cells field. The current study is aiming at preparation and structural characterization Of 10% Y2O3 stabilized ZrO2 nanometric powders. The sol-gel method is known to be easy to use for producing various kinds of materials, structured at nanometric level, so was chosen for the elaboration of powders. Different thermal treatments were applied to the obtained materials, which were consequently investigated through thermal analysis, X-ray diffraction (XRD) scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The characteristics Of Y2O3 doped zirconia powders are influenced by the processing parameters and proved promising for further applications in, for exampl...

Current Applied Physics

a b s t r a c t (Bi 0.5 Na 0.5)TiO 3 was doped in situ with 5, 8, and 11 mol% BaTiO 3 (BNT-BT x ;... more a b s t r a c t (Bi 0.5 Na 0.5)TiO 3 was doped in situ with 5, 8, and 11 mol% BaTiO 3 (BNT-BT x ; x ¼ 0.05, 0.08 and 0.11) using a sol-gel technique. The resulting powders from gel precursors showed microstructures consisting of nano-sized grains and crystalline perovskite structure. Spark plasma sintering (SPS) technique was used to prepare high densified (98e99%r theor) BNT-BT x ceramics from these nanopowders. The results confirm the spark plasma sintering method applied to nano-scale powders, obtained by sol-gel, as a viable route in producing nanostructured ceramics. The evolution of the structure and electrical properties of the ceramics with BaTiO 3 concentration (x) was investigated. The permittivity of BNT-BT 0.08 ceramic is higher (ε r ¼ 2090, at 100 kHz) than that for x ¼ 0.05 (ε r ¼ 1350) and x ¼ 0.11 (ε r ¼ 1800). BNT-BT 0.08 ceramic shows maximum values for the frequency constants (N p , N t), piezoelectric charge coefficient (d 31) and piezoelectric voltage coefficien...

Revista Romana de materiale = Romanian journal of materials = RRM

The paper's aim was to prepare and characterize ceramic powders of fully stabilized zirconia ... more The paper's aim was to prepare and characterize ceramic powders of fully stabilized zirconia (with 8 mol% yttria), and alumina, obtained through co-precipitation starting from the corresponding chlorides. Co-precipitation was taken using water or ethanol as a solvent and considering the pH influence (7.5, 10.5 and 12.5 obtained by using ammonia solution) upon precipitation was analyzed. The obtained powders were dried at 80 degrees C for 24 h and afterwards calcinated at 350 degrees C for 2 hours. The powders were evaluated through thermal analysis, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The XRD results show that 8YSZ calcinated powders is a tetragonal ZrO(2) and, concerning alumina powder, besides gamma-Al(2)O(3), delta-Al(2)O(3) was identified. The TEM examination shows that the tetragonal ZrO(2) has a spherical like morphology with a size ranging from 5 nm to 12 nm. Also, it was observed that the best condition for nanopowders ob...

Journal of Materials Science, 2015

The paper presents a simple, reproducible, controllable, and direct wet chemical synthesis method... more The paper presents a simple, reproducible, controllable, and direct wet chemical synthesis method for Zn 1-x Eu x O nanoparticles. The full understanding of decomposition mechanism of the as-obtained oxalate precipitate was achieved based on the thermal analysis correlated with the evolved gas analysis and FTIR spectroscopy. The structure, morphology, and optical luminescent properties of the Zn 1-x Eu x O nanoparticles have been investigated by X-ray diffraction, Raman spectroscopy, HRTEM, SAED, XPS, and PL. The XRD studies reveal the formation of a hexagonal wurtzite-type structure. The presence of Eu 2 O 3 cubic structure can be observed up to 0.5 mol% Eu, suggesting that the solubility of the divalent or trivalent Eu into the ZnO lattice is limited. The formation of Eu 2 O 3 secondary phase at higher Eu concentration is sustained by Raman spectroscopy and XPS, as well. The TEM investigations of the Eu-doped ZnO samples illustrate the presence of aggregates with different shapes and dimensions formed by agglomerated spherical and polyhedral nanoparticles with sizes ranging from 20 to 120 nm. The effect of europium concentration on the structural and morphological characteristics, as well as on the luminescent properties was studied with special emphasis on the europium chemical states-Eu 2? and Eu 3?. The PL measurements sustain the presence of both divalent and trivalent europium ions into the ZnO host lattice and, at the same time, an increase of its defects density induced by the dopant presence.

Chalcogenide Letters

Nanomaterials with controlled morphology have drawn significant attention due to their unique opt... more Nanomaterials with controlled morphology have drawn significant attention due to their unique optical, electrical and chemical properties originating from their quantum size. The reverse microemulsion method is one of the most recognized soft chemistry routes for the synthesis of nanocrystals with very narrow size distribution. We report on the synthesis of photoluminescent cadmium sulfide nanoparticles doped with different ions (Ag + , Mn 2+ , Zn 2+) by reverse microemulsion method. The structure and morphology of the samples were investigated by X-ray diffraction, scanning and transmission electron microscopy. The optical characterization of colloidal systems was carried out by UV-vis and photoluminescence (PL) spectroscopy. Different photoluminescent properties were obtained by varying the doping ion and its content.

Materials, 2021

In this study, zinc oxide nanoparticles were synthesized through a simple co-precipitation method... more In this study, zinc oxide nanoparticles were synthesized through a simple co-precipitation method starting from zinc acetate dihydrate and sodium hydroxide as reactants. The as-obtained ZnO nanoparticles were morphologically and structurally characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photocatalytic activity, and by determining the antimicrobial activity against Gram-negative and Gram-positive bacteria. The XRD pattern of the zinc oxide nanoparticles showed the wurtzite hexagonal structure, and its purity highlighted that the crystallinity correlated with the presence of a single product, zinc oxide. The ZnO nanoparticles have an average crystallite size of 19 ± 11 nm, which is in accordance with the microscopic data. ZnO nanoparticles were tested against methyl orange, used as a model pollutant, and it was found that they exhibit strong photocatalytic activity a...

Antibiotics, 2021

Recent years have witnessed a tremendous interest in the use of essential oils in biomedical appl... more Recent years have witnessed a tremendous interest in the use of essential oils in biomedical applications due to their intrinsic antimicrobial, antioxidant, and anticancer properties. However, their low aqueous solubility and high volatility compromise their maximum potential, thus requiring the development of efficient supports for their delivery. Hence, this manuscript focuses on developing nanostructured systems based on Fe3O4@SiO2 core–shell nanoparticles and three different types of essential oils, i.e., thyme, rosemary, and basil, to overcome these limitations. Specifically, this work represents a comparative study between co-precipitation and microwave-assisted hydrothermal methods for the synthesis of Fe3O4@SiO2 core–shell nanoparticles. All magnetic samples were characterized by X-ray diffraction (XRD), gas chromatography-mass spectrometry (GC-MS), Fourier-transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), zeta potential, scanning electron microscopy (S...

International Journal of Molecular Sciences, 2021

The development of drug-resistant microorganisms has become a critical issue for modern medicine ... more The development of drug-resistant microorganisms has become a critical issue for modern medicine and drug discovery and development with severe socio-economic and ecological implications. Since standard and conventional treatment options are generally inefficient, leading to infection persistence and spreading, novel strategies are fundamentally necessary in order to avoid serious global health problems. In this regard, both metal and metal oxide nanoparticles (NPs) demonstrated increased effectiveness as nanobiocides due to intrinsic antimicrobial properties and as nanocarriers for antimicrobial drugs. Among them, gold, silver, copper, zinc oxide, titanium oxide, magnesium oxide, and iron oxide NPs are the most preferred, owing to their proven antimicrobial mechanisms and bio/cytocompatibility. Furthermore, inorganic NPs can be incorporated or attached to organic/inorganic films, thus broadening their application within implant or catheter coatings and wound dressings. In this cont...

Nanomaterials, 2020

The present article evaluates, in qualitative and quantitative manners, the characteristics (i.e.... more The present article evaluates, in qualitative and quantitative manners, the characteristics (i.e., thickness of layers, crystal structures, growth orientation, elemental diffusion depths, edge, and screw dislocation densities), within two GaN/AlN/Si heterostructures, that alter their efficiencies as positron moderators. The structure of the GaN film, AlN buffer layer, substrate, and their growth relationships were determined through high-resolution transmission electron microscopy (HR-TEM). Data resulting from high-resolution X-ray diffraction (HR-XRD) was mathematically modeled to extract dislocation densities and correlation lengths in the GaN film. Positron depth profiling was evaluated through an experimental Doppler broadening spectroscopy (DBS) study, in order to quantify the effective positron diffusion length. The differences in values for both edge ( ρ d e ) and screw ( ρ d s ) dislocation densities, and correlation lengths (Le, Ls) found in the 690 nm GaN film, were associ...

International Journal of Pharmaceutics, 2017

The increasing rate of antibiotic resistant bacteria associated with nosocomial infections in sev... more The increasing rate of antibiotic resistant bacteria associated with nosocomial infections in severely ill patients has urged the need for new antibacterial therapies. Nanostructured materials represent emerging innovative approaches to controlled delivery of different antimicrobial drugs. Delivery systems encapsulating natural compounds with antibacterial effects, such as essential oils have shown a great potential. Herein we report the development of SiO2 mesoporous nanosystems loaded with eucalyptus (EUC), orange (ORA), and cinnamon (CIN) essential oils. These systems were characterized with respect to morphology (using scanning electron microscopy, SEM, and transmission electron microscopy, TEM), porosity (by BET and TEM analysis), chemical composition (by X-ray diffraction, XRD, and Fourier transform infrared spectrometry, FTIR) and loading capacity (by thermogravimetric analysis, TGA). The anti-bacterial and anti-adherence effects were tested against clinically relevant microbial species (Staphylococcus aureus ATCC 25923; Escherichia coli ATCC 25922; and Candida albicans ATCC 10231), while the biocompatibility was evaluated by in vitro tests with L929 mouse fibroblast cells.

Metals, 2016

The aim of this study was to develop a biocompatible coating for wound dressings, containing iron... more The aim of this study was to develop a biocompatible coating for wound dressings, containing iron oxide nanoparticles functionalized with patchouli essential oil in order to obtain improved antimicrobial properties able to prevent biofilm development and consecutive associated infections. The bioactive coating was prepared by the co-precipitation of a precursor in an alkaline solution of patchouli oil. The prepared surface was characterized by XRD (X ray diffraction), TEM (transmission electron microscopy), SAED (selected area diffraction), SEM (scanning electron microscopy) and FT-IR (Fourier transform infrared spectroscopy). The bioevaluation of the obtained coating consisted in antimicrobial, as well as in vitro and in vivo biocompatibility and biodistribution assays. The obtained coating revealed a strong anti-biofilm activity maintained up to 72 h, as well as a low cytotoxicity on mammalian cells and a good biodistribution after intraperitoneal injection in mice. These results demonstrate the promising potential of the respective coatings for the management of wound infections and for the development of soft materials with improved resistance to microbial colonization.

Applied Surface Science, 2016

In this study, we investigated the potential of MAPLE-deposited coatings mesoporous silica nanopa... more In this study, we investigated the potential of MAPLE-deposited coatings mesoporous silica nanoparticles (MSNs) to release Zinforo (ceftarolinum fosmil) in biologically active form. The MSNs were prepared by using a classic procedure with cetyltrimethylammonium bromide as sacrificial template and tetraethylorthosilicate as the monomer. The Brunauer-Emmett-Teller (BET) and transmission electron microscopy (TEM) analyses revealed network-forming granules with diameters under 100 nm and an average pore diameter of 2.33 nm. The deposited films were characterized by SEM, TEM, XRD and IR. Microbiological analyses performed on ceftaroline-loaded films demonstrated that the antibiotic was released in an active form, decreasing the microbial adherence rate and colonization of the surface. Moreover, the in vitro and in vivo assays proved the excellent biodistribution and biocompatibility of the prepared systems. Our results suggest that the obtained bioactive coatings possess a significant potential for the design of drug delivery systems and antibacterial medical-use surfaces, with great applications in bone implantology.

S-a eleborat un procedeu eficient şi nepoluant de sinteză a argintului macroporos granular prin r... more S-a eleborat un procedeu eficient şi nepoluant de sinteză a argintului macroporos granular prin reducerea Ag 2 SO 4 cu acid ascorbic, în fază heterogenă în mediu apos. Procedeul elaborat este cumparat cu procedee similare realizate prin reducerea cu acid ascorbic a AgNO 3 , şi respectiv a AgNO. Probele au fost examinate la microscopul optic şi caracterizate prin analiză XRD. Au fost estimate porozitatea şi proprietăţile lor electroconductive. Argintul granular microporos obtinut a fost caracterizat prin analiză FTIR, TG-DSC, TEM şi testat drept catod într-o celulă de electroliză în soluţie de KOH comparativ cu un catod din argint masiv. Conductivitatea electrică bună şi suprafaţa specifică mare a produsului ar putea permite utilizarea acestuia în electrochimie. An effective and green route was elaborated for synthesis of macroporous granular silver by reduction of Ag 2 SO 4 with ascorbic acid in heterogeneous phase in aqueous medium. The synthesis method was compared with similar procedures using the reduction of AgNO 3 or AgNO 2 with ascorbic acid. The samples were examined by optical microscopy, XRD patterns as well as porosity and electroconductive properties.The product was characterized by FTIR, TG-DSC, TEM and tested as cathode in an electrolysis cell in KOH solution comparative to a bulk silver cathode. The good electric conductivity and high specific aria of the product may sustain its electrochemical use.

Digest Journal of Nanomaterials and Biostructures

Recently, the fabrication of shape controlled magnetite nanostructure was published by Zheng et a... more Recently, the fabrication of shape controlled magnetite nanostructure was published by Zheng et al. [16]. They concluded that magnetite shape can be controlled by precursor's concentrations and molecular weight of the polyethylene glycol which is used as dispersant. They found that cubic magnetite is obtained if 0.2M Fe 3+ , 0.1M Fe 2+ and 10-3 mol/L PEG (M.W.=20.000) solutions are used; nanorods with geometrical characteristics of 10nm x 100-200nm are obtained if solutions of 2.0x10-2 Fe 3+ , 1.0x10-2 Fe 2+ and 10-3 mol/L PEG (M.W.=20.000) are used and dendrides are obtained if solutions of 2.0x10-3 Fe 3+ , 1.0x10-3 Fe 2+ and 2.0x10-3 mol/L PEG (M.W.=20.000) are used. Also, the molecular weight of PEG leads to morphological changes of , A. FICAI, B.

MATERIALE PLASTICE

Bimetallic Pd-Ag nanoparticles (NPs) were obtained by polyol method in the presence of poly (viny... more Bimetallic Pd-Ag nanoparticles (NPs) were obtained by polyol method in the presence of poly (vinylpyrrolidone), PVP, as capping agent. The reduction of silver and palladium precursors was performed in argon inert atmosphere by successive reduction, or coreduction approach. In the successive reduction, AgNO 3 solution was injected in the ethylene glycol solution of PVP at 140°C, followed by the injection of [Pd(NH 3) 4 ]Cl 2 solution. The obtained bimetallic Pd-Ag NPs exhibited cluster structure, with the surface reach in silver. The NPs size was in the range of 30-58.5 nm with the average dimention of 41.5 nm. The coreduction approach consists in the hot injection of both metal precursors as complex ammine dissolved in ethylene glycol. By this method, smaller Pd-Ag NPs with the average sizes in the range 16-30 nm were obtained, depending on the synthesis parameters. The influence of metal cations : PVP molar ratio, metal cations concentration, Ag : Pd atomic ratio and the reduction temperature on the composition and morphology of the bimetallic NPs was studied. For both reduction approaches, based on the experimental data, two different reduction patways were proposed.

Revista Romana de materiale = Romanian journal of materials = RRM

ABSTRACT

Export Date: 29 April 2015, CODEN: SBPSF, References: Weißenrieder, K.S., Muller, J., Conductivit... more Export Date: 29 April 2015, CODEN: SBPSF, References: Weißenrieder, K.S., Muller, J., Conductivity model for sputtered ZnO-thin film gas sensors (1997) Thin Solid Films, 300 (1-2), pp. 30-41. , May;

Metalurgia international

Nanopowders based on Co-doped TiO2 anatase with homogeneous distribution of doping element were o... more Nanopowders based on Co-doped TiO2 anatase with homogeneous distribution of doping element were obtained by a hydrothermal process using KOH as mineralizing agent. The microstructure analysis made by RXD and SEM show the formation of nanopowders with single phase anatase structure. The stability and phase evolution of crystallized TiO2 during thermal treatment vs. Co content was studied using DSC-TG methods. The estimation of activation energy for hydrothermal crystallization was done based on XRD measurement of nanopowders obtained at different temperatures and times based on Avrami approach. The results show that Co - doped anatase nanopowders obtained by the proposed hydrothermal procedure show a good stability for potential applications in photo-catalytic processes and diluted magnetic semiconductors:

Revista Romana de materiale = Romanian journal of materials = RRM

The purpose of this study is to obtain nanometric zirconia powders, by sol-gel method, using prec... more The purpose of this study is to obtain nanometric zirconia powders, by sol-gel method, using precursors of different chemical nature - inorganic (ZrCl4) and organic (C12H28O4Zr). The obtained gels were dried at 100 degrees C, and then heat treated to 1000 degrees C for 2 hours. In order to identify obtained phases and their degree of crystallinity, powders were analyzed using X-ray diffraction. Analyses of scanning electron microscopy and transmission electron microscopy have been used to investigate the morphology and size of the obtained powders. Experimental analyzes show that, from different precursors (organic and inorganic), nanometric powders of partially stabilized zirconia with CaO are obtained.

Journal of Optoelectronics and Advanced Materials

The attractive properties of zirconia, particularly fracture toughness, wear resistance and chemi... more The attractive properties of zirconia, particularly fracture toughness, wear resistance and chemical stability, have led to vast research efforts designed to investigate, characterize and develop such materials. Applications vary from structural, mechanical, biomedical to electrical, especially the fuel cells field. The current study is aiming at preparation and structural characterization Of 10% Y2O3 stabilized ZrO2 nanometric powders. The sol-gel method is known to be easy to use for producing various kinds of materials, structured at nanometric level, so was chosen for the elaboration of powders. Different thermal treatments were applied to the obtained materials, which were consequently investigated through thermal analysis, X-ray diffraction (XRD) scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The characteristics Of Y2O3 doped zirconia powders are influenced by the processing parameters and proved promising for further applications in, for exampl...

Current Applied Physics

a b s t r a c t (Bi 0.5 Na 0.5)TiO 3 was doped in situ with 5, 8, and 11 mol% BaTiO 3 (BNT-BT x ;... more a b s t r a c t (Bi 0.5 Na 0.5)TiO 3 was doped in situ with 5, 8, and 11 mol% BaTiO 3 (BNT-BT x ; x ¼ 0.05, 0.08 and 0.11) using a sol-gel technique. The resulting powders from gel precursors showed microstructures consisting of nano-sized grains and crystalline perovskite structure. Spark plasma sintering (SPS) technique was used to prepare high densified (98e99%r theor) BNT-BT x ceramics from these nanopowders. The results confirm the spark plasma sintering method applied to nano-scale powders, obtained by sol-gel, as a viable route in producing nanostructured ceramics. The evolution of the structure and electrical properties of the ceramics with BaTiO 3 concentration (x) was investigated. The permittivity of BNT-BT 0.08 ceramic is higher (ε r ¼ 2090, at 100 kHz) than that for x ¼ 0.05 (ε r ¼ 1350) and x ¼ 0.11 (ε r ¼ 1800). BNT-BT 0.08 ceramic shows maximum values for the frequency constants (N p , N t), piezoelectric charge coefficient (d 31) and piezoelectric voltage coefficien...

Revista Romana de materiale = Romanian journal of materials = RRM

The paper's aim was to prepare and characterize ceramic powders of fully stabilized zirconia ... more The paper's aim was to prepare and characterize ceramic powders of fully stabilized zirconia (with 8 mol% yttria), and alumina, obtained through co-precipitation starting from the corresponding chlorides. Co-precipitation was taken using water or ethanol as a solvent and considering the pH influence (7.5, 10.5 and 12.5 obtained by using ammonia solution) upon precipitation was analyzed. The obtained powders were dried at 80 degrees C for 24 h and afterwards calcinated at 350 degrees C for 2 hours. The powders were evaluated through thermal analysis, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The XRD results show that 8YSZ calcinated powders is a tetragonal ZrO(2) and, concerning alumina powder, besides gamma-Al(2)O(3), delta-Al(2)O(3) was identified. The TEM examination shows that the tetragonal ZrO(2) has a spherical like morphology with a size ranging from 5 nm to 12 nm. Also, it was observed that the best condition for nanopowders ob...

Journal of Materials Science, 2015

The paper presents a simple, reproducible, controllable, and direct wet chemical synthesis method... more The paper presents a simple, reproducible, controllable, and direct wet chemical synthesis method for Zn 1-x Eu x O nanoparticles. The full understanding of decomposition mechanism of the as-obtained oxalate precipitate was achieved based on the thermal analysis correlated with the evolved gas analysis and FTIR spectroscopy. The structure, morphology, and optical luminescent properties of the Zn 1-x Eu x O nanoparticles have been investigated by X-ray diffraction, Raman spectroscopy, HRTEM, SAED, XPS, and PL. The XRD studies reveal the formation of a hexagonal wurtzite-type structure. The presence of Eu 2 O 3 cubic structure can be observed up to 0.5 mol% Eu, suggesting that the solubility of the divalent or trivalent Eu into the ZnO lattice is limited. The formation of Eu 2 O 3 secondary phase at higher Eu concentration is sustained by Raman spectroscopy and XPS, as well. The TEM investigations of the Eu-doped ZnO samples illustrate the presence of aggregates with different shapes and dimensions formed by agglomerated spherical and polyhedral nanoparticles with sizes ranging from 20 to 120 nm. The effect of europium concentration on the structural and morphological characteristics, as well as on the luminescent properties was studied with special emphasis on the europium chemical states-Eu 2? and Eu 3?. The PL measurements sustain the presence of both divalent and trivalent europium ions into the ZnO host lattice and, at the same time, an increase of its defects density induced by the dopant presence.

Chalcogenide Letters

Nanomaterials with controlled morphology have drawn significant attention due to their unique opt... more Nanomaterials with controlled morphology have drawn significant attention due to their unique optical, electrical and chemical properties originating from their quantum size. The reverse microemulsion method is one of the most recognized soft chemistry routes for the synthesis of nanocrystals with very narrow size distribution. We report on the synthesis of photoluminescent cadmium sulfide nanoparticles doped with different ions (Ag + , Mn 2+ , Zn 2+) by reverse microemulsion method. The structure and morphology of the samples were investigated by X-ray diffraction, scanning and transmission electron microscopy. The optical characterization of colloidal systems was carried out by UV-vis and photoluminescence (PL) spectroscopy. Different photoluminescent properties were obtained by varying the doping ion and its content.