Ossi Horowitz - Academia.edu (original) (raw)

Papers by Ossi Horowitz

Journal of Optoelectronics and Advanced Materials

Applied Surface Science, Apr 1, 2014

Abstract Nano hydroxyapatite doped with zinc (0.2 wt%), silver (0.25 wt%) and gold (0.025 wt%), (... more Abstract Nano hydroxyapatite doped with zinc (0.2 wt%), silver (0.25 wt%) and gold (0.025 wt%), (HAP), has been obtained by an innovative wet chemical approach, coupled with a reduction process for silver and gold. The synthesized multi-substituted nano HAP was freeze-dried and calcined at 650 °C. Nano HAP has been characterized by XRD, FTIR spectroscopy and imaging techniques: TEM, SEM and AFM. Then, nano HAP was mixed with previously synthesized silver nanoparticles (AgNPs), in the amount of 9 wt%, to give a novel material (HAP-Ag). The AgNPs were prepared by the reduction of silver nitrate with glucose in alkaline medium. TEM and UV–Vis confirmed the formation of AgNPs with an average size of 12 nm. Further, organic matrix composites were obtained from a filler made of HAP and/or HAP-Ag and a mixture of monomers (such as bis-GMA and TEG-DMA), which were polymerized at various compositions in AgNPs content up to 5.4 wt%. Antibacterial activities of these composites were investigated against several different pathogenic species: Escherichia coli, Staphylococcus aureus, Staphylococcus spp., Bacillus cereus, and Candida albicans, using the Kirby–Bauer disk-diffusion method. Antibacterial activities are enhanced with increasing of silver content within composites. These effects clearly reveal that AgNPs can be effectively utilized in combination with multi-substituted HAP and polymeric matrix, both used as carriers, in order to improve their efficiency against various pathogenic species. These composites can be considered a promising antimicrobial material for coating of orthopedic and dental implants or used as bone cements in surgical applications.

Particulate Science and Technology, Nov 30, 2015

This study reports the synthesis of new porous nanohydroxyapatites (HAPs) substituted with differ... more This study reports the synthesis of new porous nanohydroxyapatites (HAPs) substituted with different Zn contents (HAP_Zn) employing calcium and zinc nitrates and diammonium hydrogen phosphate as precursors. The synthesis was conducted in the presence of a surfactant, L-asparagine, for controlling the pore size distribution and morphology of obtained nanopowders, using a co-precipitation route. Thus a new approach leading to HAP_Zn nanopowders with improved nucleation and crystallization ability was developed. After maturation treatment of dispersions and filtration, the precipitate was lyophilized and ground. Part of the samples was calcined at 300°C for 1 h. The zinc content in the nanoHAPs varies from 0.2 to 10 wt% (substitution degree of Ca by Zn from 0.3 to 15.8 mole %). XRD investigations indicated HAP as the unique phase present and the nanostructured nature of the obtained HAPs. FTIR spectra also confirmed the presence of HAP structure. TEM, SEM, and AFM images showed the mor...

Studia Universitatis Babes-bolyai Chemia, 2008

Applied Surface Science, 2014

Abstract Nano hydroxyapatite doped with zinc (0.2 wt%), silver (0.25 wt%) and gold (0.025 wt%), (... more Abstract Nano hydroxyapatite doped with zinc (0.2 wt%), silver (0.25 wt%) and gold (0.025 wt%), (HAP), has been obtained by an innovative wet chemical approach, coupled with a reduction process for silver and gold. The synthesized multi-substituted nano HAP was freeze-dried and calcined at 650 °C. Nano HAP has been characterized by XRD, FTIR spectroscopy and imaging techniques: TEM, SEM and AFM. Then, nano HAP was mixed with previously synthesized silver nanoparticles (AgNPs), in the amount of 9 wt%, to give a novel material (HAP-Ag). The AgNPs were prepared by the reduction of silver nitrate with glucose in alkaline medium. TEM and UV–Vis confirmed the formation of AgNPs with an average size of 12 nm. Further, organic matrix composites were obtained from a filler made of HAP and/or HAP-Ag and a mixture of monomers (such as bis-GMA and TEG-DMA), which were polymerized at various compositions in AgNPs content up to 5.4 wt%. Antibacterial activities of these composites were investigated against several different pathogenic species: Escherichia coli, Staphylococcus aureus, Staphylococcus spp., Bacillus cereus, and Candida albicans, using the Kirby–Bauer disk-diffusion method. Antibacterial activities are enhanced with increasing of silver content within composites. These effects clearly reveal that AgNPs can be effectively utilized in combination with multi-substituted HAP and polymeric matrix, both used as carriers, in order to improve their efficiency against various pathogenic species. These composites can be considered a promising antimicrobial material for coating of orthopedic and dental implants or used as bone cements in surgical applications.

Studia Universitatis Babeș-Bolyai Chemia

Chimie pentru ingineri : [curs]. Vol. 1, 2007

Annals of the Academy of Romanian Scientists Series on Physics and Chemistry

Synthetic hydroxyapatite (Ca10(PO4)6(OH)2, HAP) is widely used in regards to orthopedic applicati... more Synthetic hydroxyapatite (Ca10(PO4)6(OH)2, HAP) is widely used in regards to orthopedic applications due to its similarity to the mineral component in bone. However, while HAP aids with osseointegration it does nothing when it comes to orthopedic infections. Moreover, the prevalence of antibiotic resistance makes treatment even more difficult. In view of this, adding silver to hydroxyapatite has been a focus of many studies due to the combined bioactivity of HAP and excellent antibacterial properties of Ag. The present work brings a brief introduction to more recent studies regarding the HAP-silver combination and its effect on different pathogenic strains. The effect of silver on benign cells is also discussed based on in vitro cultures and in vivo studies.

Studia Universitatis Babeș-Bolyai Chemia

The stability and solubility of curcumin, CCM, can be enhanced by complexation with whey protein ... more The stability and solubility of curcumin, CCM, can be enhanced by complexation with whey protein concentrate (WPC). The CCM-WPC of 1:1 and 1:0.5 molar ratio complexes were encapsulated by two methods, namely spray drying (SD) and freeze drying (FD). The major objective of this work is to determine the stability and solubility of the CCM-WPC complexes encapsulated by SD and FD method. The X-ray diffraction and thermogravimetric analysis were performed on raw CCM and WPC, and on their complexes. The changes in thermal degradation and in crystallinity suggest the formation of these CCM-WPC complexes. Scanning electron microscopy images showed that the used methods influenced the morphology and the properties of the formed complexes. The stability and solubility of curcumin are enhanced by complexation in both encapsulation methods. However, comparing the used molar ratio and drying methods, the results are various. The solubility of samples obtained by FD method was higher than in the case of the SD method, which can explain the difference of their morphology (FD samples are more amorphous than SD samples). The antioxidant property of curcumin and its protein-complexes compared to vitamin C showed that CCM and its complexes have a lower IC50 value than vitamin C, i.e., the antioxidant effect of CCM is higher. The addition of WPC improved the antioxidant activity of CCM, probably due to its encapsulation in the protein. Our results suggest that the 1CCM-1WPC_SD complex is the best antioxidant from these studied CCM-WPC complexes.

The synthesized forsterite is usually associated with various amounts of periclase (MgO), silicon... more The synthesized forsterite is usually associated with various amounts of periclase (MgO), silicon dioxide (SiO2), and enstatite (MgSiO3). However, the role of different thermal treatment conditions on the optimal formation of pure forsterite and its antimicrobial activity is not yet deeply evaluated. So, the goal of this study was the preparation, characterization and in vitro antibacterial activity evaluation of forsterite nanopowder (FS, Mg2SiO4) obtained by two major methods, namely sol-gel (FSsg) and co-precipitation (FSpp). To assess the best working temperature for the preparation of FSsg and FSpp, the synthesis and thermal treatment conditions were optimized on the basis of thermal gravimetric (TG) and differential scanning calorimetric (DSC) analysis performed on the dried gel and dried co-precipitated solid, respectively. The FSsg and FSpp powders were characterized by X-ray powder diffraction (XRD) indicating a high purity for both FSs and FSpp powders. The morphology of F...

Powder Technology, 2013

Abstract In the present study a new strategy of synthesis was developed for nanostructured calciu... more Abstract In the present study a new strategy of synthesis was developed for nanostructured calcium phosphates, such as hydroxyapatite (HAP) or silicon, magnesium and zinc modified hydroxyapatites of controlled characteristics (such as the shape and size of nanoparticles, porosity and crystallinity) by precipitation reactions. These inorganic powders were jointly used with chitosan (CHI) and collagen type I (COL) to manufacture fibrous biocomposite scaffolds made of self-assembled layers by using layer by layer technique for cell cultures. The resulting materials were characterized by using X-ray diffraction, SEM, TEM and AFM. This work also reports the structural data obtained on the surface of the newly prepared nanostructured porous scaffolds made of self-assembled nanoHAP–Si(0.2%)–Mg(0.6%)–Zn(0.2%)/CHI/COL layers at 7 days in human osteoblastic cell culture. A new porous structure was found by SEM imaging on the surface of these scaffolds due to the cells and scaffold interactions. This structure is apparently similar to the bone tissue. Our data have indicated that the incorporation of small amounts of silicon, magnesium and zinc within the nanoHAP lattice improved the biological activity of human osteoblasts on these scaffolds, in vitro. The data have revealed the high importance of HAP nanostructure and its composition in the preparation of fibrous scaffolds with potential applications in particle technology, bone tissue engineering and nano medicine.

Environmental Science and Pollution Research

Studia Universitatis Babeș-Bolyai Chemia, 2017

The thermal stability over time of the pure and multisubstituted hydroxyapatite (HAP) pastes, dop... more The thermal stability over time of the pure and multisubstituted hydroxyapatite (HAP) pastes, doped with magnesium, silicon, strontium and zinc, synthesized using aqueous precipitation method were investigated by thermal analyses (TG-DTA). Results show high thermal stability of pure and multidoped hydroxyapatite pastes, up to 1000 o C and even after ageing for 1 year, making these pastes promising nano materials for medical applications.

Studia Universitatis Babeș-Bolyai Chemia, 2017

In order to obtain a low crystalline nanohydrxyapatite (HAP), suitable for biomedical application... more In order to obtain a low crystalline nanohydrxyapatite (HAP), suitable for biomedical application, a new synthesis procedure was developed, based on the aqueous precipitation method, at room temperature, without any additives. Accordingly, lyophilized HAP powders, both calcined and non calcined, were prepared, and characterized by XRD, TEM and AFM imaging, FTIR spectroscopy, zeta potential and BET measurements. The results confirmed HAP as the only phase present. The high porosity of this nanomaterial is attained. The nanoparticle size and shape as well as the crystallinity degree of the obtained HAP samples were also determined.

Journal of Mathematical Chemistry, 2017

The geometric and energetic preference of the possible isomers of four tautomeric triazine deriva... more The geometric and energetic preference of the possible isomers of four tautomeric triazine derivatives has been investigated by density functional theory and topological calculations and their thermodynamic stability was assessed. For the monoxime series the amino keto tautomer is favored by 2.6 kcal/mol (10.9 kJ/mol) as compared to the enol form, while the lowest energy imino isomer is 4.1 kcal/mol (17.1 kJ/mol) higher in energy. However, for the dioxime tautomer series the imino keto tautomer is 4.2 kcal/mol (17.6 kJ/mol) lower in energy as compared to the most stable amino keto tautomer. The computed excitation energies for the first electron transitions agree with the experimental observations.

Applied Surface Science, 2014

Nano hydroxyapatite doped with zinc (0.2 wt%), silver (0.25 wt%) and gold (0.025 wt%), (HAP), has... more Nano hydroxyapatite doped with zinc (0.2 wt%), silver (0.25 wt%) and gold (0.025 wt%), (HAP), has been obtained by an innovative wet chemical approach, coupled with a reduction process for silver and gold. The synthesized multi-substituted nano HAP was freeze-dried and calcined at 650 °C. Nano HAP has been characterized by XRD, FTIR spectroscopy and imaging techniques: TEM, SEM and AFM. Then, nano HAP was mixed with previously synthesized silver nanoparticles (AgNPs), in the amount of 9 wt%, to give a novel material (HAP-Ag). The AgNPs were prepared by the reduction of silver nitrate with glucose in alkaline medium. TEM and UV–Vis confirmed the formation of AgNPs with an average size of 12 nm. Further, organic matrix composites were obtained from a filler made of HAP and/or HAP-Ag and a mixture of monomers (such as bis-GMA and TEG-DMA), which were polymerized at various compositions in AgNPs content up to 5.4 wt%. Antibacterial activities of these composites were investigated agains...

Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. Agriculture, 2010

Making biodegradable plastics is a concern of recent years, research in this field from universit... more Making biodegradable plastics is a concern of recent years, research in this field from universities, research institutes and enterprises are continuously developing. Biodegradable loose fill shock absorbent packaging are also part of the large class of biodegradable plastics and it is necessary for them to ensure, besides biodegradability, a number of technical requirements deriving from their utilization purposes: protection of breakable products during handling and transport. Packaging properties depends on both the type and proportion of materials that are part of the formula and the technology used in its manufacture, process characterized by certain technological parameters. This paper presents some results obtained making a biodegradable loose fill packaging by corn-starch extrusion in the presence of plasticizers.

Journal of Optoelectronics and Advanced Materials

Applied Surface Science, Apr 1, 2014

Abstract Nano hydroxyapatite doped with zinc (0.2 wt%), silver (0.25 wt%) and gold (0.025 wt%), (... more Abstract Nano hydroxyapatite doped with zinc (0.2 wt%), silver (0.25 wt%) and gold (0.025 wt%), (HAP), has been obtained by an innovative wet chemical approach, coupled with a reduction process for silver and gold. The synthesized multi-substituted nano HAP was freeze-dried and calcined at 650 °C. Nano HAP has been characterized by XRD, FTIR spectroscopy and imaging techniques: TEM, SEM and AFM. Then, nano HAP was mixed with previously synthesized silver nanoparticles (AgNPs), in the amount of 9 wt%, to give a novel material (HAP-Ag). The AgNPs were prepared by the reduction of silver nitrate with glucose in alkaline medium. TEM and UV–Vis confirmed the formation of AgNPs with an average size of 12 nm. Further, organic matrix composites were obtained from a filler made of HAP and/or HAP-Ag and a mixture of monomers (such as bis-GMA and TEG-DMA), which were polymerized at various compositions in AgNPs content up to 5.4 wt%. Antibacterial activities of these composites were investigated against several different pathogenic species: Escherichia coli, Staphylococcus aureus, Staphylococcus spp., Bacillus cereus, and Candida albicans, using the Kirby–Bauer disk-diffusion method. Antibacterial activities are enhanced with increasing of silver content within composites. These effects clearly reveal that AgNPs can be effectively utilized in combination with multi-substituted HAP and polymeric matrix, both used as carriers, in order to improve their efficiency against various pathogenic species. These composites can be considered a promising antimicrobial material for coating of orthopedic and dental implants or used as bone cements in surgical applications.

Particulate Science and Technology, Nov 30, 2015

This study reports the synthesis of new porous nanohydroxyapatites (HAPs) substituted with differ... more This study reports the synthesis of new porous nanohydroxyapatites (HAPs) substituted with different Zn contents (HAP_Zn) employing calcium and zinc nitrates and diammonium hydrogen phosphate as precursors. The synthesis was conducted in the presence of a surfactant, L-asparagine, for controlling the pore size distribution and morphology of obtained nanopowders, using a co-precipitation route. Thus a new approach leading to HAP_Zn nanopowders with improved nucleation and crystallization ability was developed. After maturation treatment of dispersions and filtration, the precipitate was lyophilized and ground. Part of the samples was calcined at 300°C for 1 h. The zinc content in the nanoHAPs varies from 0.2 to 10 wt% (substitution degree of Ca by Zn from 0.3 to 15.8 mole %). XRD investigations indicated HAP as the unique phase present and the nanostructured nature of the obtained HAPs. FTIR spectra also confirmed the presence of HAP structure. TEM, SEM, and AFM images showed the mor...

Studia Universitatis Babes-bolyai Chemia, 2008

Applied Surface Science, 2014

Abstract Nano hydroxyapatite doped with zinc (0.2 wt%), silver (0.25 wt%) and gold (0.025 wt%), (... more Abstract Nano hydroxyapatite doped with zinc (0.2 wt%), silver (0.25 wt%) and gold (0.025 wt%), (HAP), has been obtained by an innovative wet chemical approach, coupled with a reduction process for silver and gold. The synthesized multi-substituted nano HAP was freeze-dried and calcined at 650 °C. Nano HAP has been characterized by XRD, FTIR spectroscopy and imaging techniques: TEM, SEM and AFM. Then, nano HAP was mixed with previously synthesized silver nanoparticles (AgNPs), in the amount of 9 wt%, to give a novel material (HAP-Ag). The AgNPs were prepared by the reduction of silver nitrate with glucose in alkaline medium. TEM and UV–Vis confirmed the formation of AgNPs with an average size of 12 nm. Further, organic matrix composites were obtained from a filler made of HAP and/or HAP-Ag and a mixture of monomers (such as bis-GMA and TEG-DMA), which were polymerized at various compositions in AgNPs content up to 5.4 wt%. Antibacterial activities of these composites were investigated against several different pathogenic species: Escherichia coli, Staphylococcus aureus, Staphylococcus spp., Bacillus cereus, and Candida albicans, using the Kirby–Bauer disk-diffusion method. Antibacterial activities are enhanced with increasing of silver content within composites. These effects clearly reveal that AgNPs can be effectively utilized in combination with multi-substituted HAP and polymeric matrix, both used as carriers, in order to improve their efficiency against various pathogenic species. These composites can be considered a promising antimicrobial material for coating of orthopedic and dental implants or used as bone cements in surgical applications.

Studia Universitatis Babeș-Bolyai Chemia

Chimie pentru ingineri : [curs]. Vol. 1, 2007

Annals of the Academy of Romanian Scientists Series on Physics and Chemistry

Synthetic hydroxyapatite (Ca10(PO4)6(OH)2, HAP) is widely used in regards to orthopedic applicati... more Synthetic hydroxyapatite (Ca10(PO4)6(OH)2, HAP) is widely used in regards to orthopedic applications due to its similarity to the mineral component in bone. However, while HAP aids with osseointegration it does nothing when it comes to orthopedic infections. Moreover, the prevalence of antibiotic resistance makes treatment even more difficult. In view of this, adding silver to hydroxyapatite has been a focus of many studies due to the combined bioactivity of HAP and excellent antibacterial properties of Ag. The present work brings a brief introduction to more recent studies regarding the HAP-silver combination and its effect on different pathogenic strains. The effect of silver on benign cells is also discussed based on in vitro cultures and in vivo studies.

Studia Universitatis Babeș-Bolyai Chemia

The stability and solubility of curcumin, CCM, can be enhanced by complexation with whey protein ... more The stability and solubility of curcumin, CCM, can be enhanced by complexation with whey protein concentrate (WPC). The CCM-WPC of 1:1 and 1:0.5 molar ratio complexes were encapsulated by two methods, namely spray drying (SD) and freeze drying (FD). The major objective of this work is to determine the stability and solubility of the CCM-WPC complexes encapsulated by SD and FD method. The X-ray diffraction and thermogravimetric analysis were performed on raw CCM and WPC, and on their complexes. The changes in thermal degradation and in crystallinity suggest the formation of these CCM-WPC complexes. Scanning electron microscopy images showed that the used methods influenced the morphology and the properties of the formed complexes. The stability and solubility of curcumin are enhanced by complexation in both encapsulation methods. However, comparing the used molar ratio and drying methods, the results are various. The solubility of samples obtained by FD method was higher than in the case of the SD method, which can explain the difference of their morphology (FD samples are more amorphous than SD samples). The antioxidant property of curcumin and its protein-complexes compared to vitamin C showed that CCM and its complexes have a lower IC50 value than vitamin C, i.e., the antioxidant effect of CCM is higher. The addition of WPC improved the antioxidant activity of CCM, probably due to its encapsulation in the protein. Our results suggest that the 1CCM-1WPC_SD complex is the best antioxidant from these studied CCM-WPC complexes.

The synthesized forsterite is usually associated with various amounts of periclase (MgO), silicon... more The synthesized forsterite is usually associated with various amounts of periclase (MgO), silicon dioxide (SiO2), and enstatite (MgSiO3). However, the role of different thermal treatment conditions on the optimal formation of pure forsterite and its antimicrobial activity is not yet deeply evaluated. So, the goal of this study was the preparation, characterization and in vitro antibacterial activity evaluation of forsterite nanopowder (FS, Mg2SiO4) obtained by two major methods, namely sol-gel (FSsg) and co-precipitation (FSpp). To assess the best working temperature for the preparation of FSsg and FSpp, the synthesis and thermal treatment conditions were optimized on the basis of thermal gravimetric (TG) and differential scanning calorimetric (DSC) analysis performed on the dried gel and dried co-precipitated solid, respectively. The FSsg and FSpp powders were characterized by X-ray powder diffraction (XRD) indicating a high purity for both FSs and FSpp powders. The morphology of F...

Powder Technology, 2013

Abstract In the present study a new strategy of synthesis was developed for nanostructured calciu... more Abstract In the present study a new strategy of synthesis was developed for nanostructured calcium phosphates, such as hydroxyapatite (HAP) or silicon, magnesium and zinc modified hydroxyapatites of controlled characteristics (such as the shape and size of nanoparticles, porosity and crystallinity) by precipitation reactions. These inorganic powders were jointly used with chitosan (CHI) and collagen type I (COL) to manufacture fibrous biocomposite scaffolds made of self-assembled layers by using layer by layer technique for cell cultures. The resulting materials were characterized by using X-ray diffraction, SEM, TEM and AFM. This work also reports the structural data obtained on the surface of the newly prepared nanostructured porous scaffolds made of self-assembled nanoHAP–Si(0.2%)–Mg(0.6%)–Zn(0.2%)/CHI/COL layers at 7 days in human osteoblastic cell culture. A new porous structure was found by SEM imaging on the surface of these scaffolds due to the cells and scaffold interactions. This structure is apparently similar to the bone tissue. Our data have indicated that the incorporation of small amounts of silicon, magnesium and zinc within the nanoHAP lattice improved the biological activity of human osteoblasts on these scaffolds, in vitro. The data have revealed the high importance of HAP nanostructure and its composition in the preparation of fibrous scaffolds with potential applications in particle technology, bone tissue engineering and nano medicine.

Environmental Science and Pollution Research

Studia Universitatis Babeș-Bolyai Chemia, 2017

The thermal stability over time of the pure and multisubstituted hydroxyapatite (HAP) pastes, dop... more The thermal stability over time of the pure and multisubstituted hydroxyapatite (HAP) pastes, doped with magnesium, silicon, strontium and zinc, synthesized using aqueous precipitation method were investigated by thermal analyses (TG-DTA). Results show high thermal stability of pure and multidoped hydroxyapatite pastes, up to 1000 o C and even after ageing for 1 year, making these pastes promising nano materials for medical applications.

Studia Universitatis Babeș-Bolyai Chemia, 2017

In order to obtain a low crystalline nanohydrxyapatite (HAP), suitable for biomedical application... more In order to obtain a low crystalline nanohydrxyapatite (HAP), suitable for biomedical application, a new synthesis procedure was developed, based on the aqueous precipitation method, at room temperature, without any additives. Accordingly, lyophilized HAP powders, both calcined and non calcined, were prepared, and characterized by XRD, TEM and AFM imaging, FTIR spectroscopy, zeta potential and BET measurements. The results confirmed HAP as the only phase present. The high porosity of this nanomaterial is attained. The nanoparticle size and shape as well as the crystallinity degree of the obtained HAP samples were also determined.

Journal of Mathematical Chemistry, 2017

The geometric and energetic preference of the possible isomers of four tautomeric triazine deriva... more The geometric and energetic preference of the possible isomers of four tautomeric triazine derivatives has been investigated by density functional theory and topological calculations and their thermodynamic stability was assessed. For the monoxime series the amino keto tautomer is favored by 2.6 kcal/mol (10.9 kJ/mol) as compared to the enol form, while the lowest energy imino isomer is 4.1 kcal/mol (17.1 kJ/mol) higher in energy. However, for the dioxime tautomer series the imino keto tautomer is 4.2 kcal/mol (17.6 kJ/mol) lower in energy as compared to the most stable amino keto tautomer. The computed excitation energies for the first electron transitions agree with the experimental observations.

Applied Surface Science, 2014

Nano hydroxyapatite doped with zinc (0.2 wt%), silver (0.25 wt%) and gold (0.025 wt%), (HAP), has... more Nano hydroxyapatite doped with zinc (0.2 wt%), silver (0.25 wt%) and gold (0.025 wt%), (HAP), has been obtained by an innovative wet chemical approach, coupled with a reduction process for silver and gold. The synthesized multi-substituted nano HAP was freeze-dried and calcined at 650 °C. Nano HAP has been characterized by XRD, FTIR spectroscopy and imaging techniques: TEM, SEM and AFM. Then, nano HAP was mixed with previously synthesized silver nanoparticles (AgNPs), in the amount of 9 wt%, to give a novel material (HAP-Ag). The AgNPs were prepared by the reduction of silver nitrate with glucose in alkaline medium. TEM and UV–Vis confirmed the formation of AgNPs with an average size of 12 nm. Further, organic matrix composites were obtained from a filler made of HAP and/or HAP-Ag and a mixture of monomers (such as bis-GMA and TEG-DMA), which were polymerized at various compositions in AgNPs content up to 5.4 wt%. Antibacterial activities of these composites were investigated agains...

Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. Agriculture, 2010

Making biodegradable plastics is a concern of recent years, research in this field from universit... more Making biodegradable plastics is a concern of recent years, research in this field from universities, research institutes and enterprises are continuously developing. Biodegradable loose fill shock absorbent packaging are also part of the large class of biodegradable plastics and it is necessary for them to ensure, besides biodegradability, a number of technical requirements deriving from their utilization purposes: protection of breakable products during handling and transport. Packaging properties depends on both the type and proportion of materials that are part of the formula and the technology used in its manufacture, process characterized by certain technological parameters. This paper presents some results obtained making a biodegradable loose fill packaging by corn-starch extrusion in the presence of plasticizers.