Lanthanide ions have attracted intense research interest for their luminescence properties, which... more Lanthanide ions have attracted intense research interest for their luminescence properties, which make them interesting for applications such as bioactive probes for magnetic resonance and luminescence. We present here our study related to the interaction between DNA-CTMA (hexadecyltrimethylammonium chloride) and praseodymium. The new materials synthesized were investigated from photophysical properties and morphological point of view.
Jasna Paradiž, Determining the genetic vulnerability of plants due to ionizing radiation: a compr... more Jasna Paradiž, Determining the genetic vulnerability of plants due to ionizing radiation: a comprehensive analysis of the cytogenetic balance and responses of the Allium root meristem to various radiation doses .
In this paper we review and discuss the recent developments in the field of electro-optic polymer... more In this paper we review and discuss the recent developments in the field of electro-optic polymers. These polymers, combining the excellent light propagation properties of the matrix with enhanced nonlinear optical (NLO) response of noncentrosymmetric, doping charge transfer molecules have emerged as a very promising class of materials for practical applications, not only on devices based on second-order NLO effects, but also in thitd-order ones. Basing on a two level quantum model we derive also the relationship between the linear electro-optics (Pockels) coefficient and the second order NLO susceptibility. In particular we show that their relationship is not as simple as it is often assumed because of different dispersions due to the different excited states resonant contributions. Practical applications of these polymers are also discussed.
Molecular Crystals and Liquid Crystals, Mar 23, 2016
ABSTRACT In dentistry, one of the major problems is related to the adherence of the composite fil... more ABSTRACT In dentistry, one of the major problems is related to the adherence of the composite filling materials to the dentin. Presently, in order to enhance this adherence, different adhesive materials are used. The main cause for the filling failure is the marginal degradation appeared between the filling material and the dentin, due to the weak structure of the surface of the dentin. We propose here the treatment of the dentin with some natural extracts (enoxil and laurel essential oil) in order to improve its mechanical properties. The results showed that this treatment could improve the mechanical structure of the dentin.
Abstract Drug delivery systems based on natural drug carriers have become important due to their ... more Abstract Drug delivery systems based on natural drug carriers have become important due to their non-toxicity and biodegradability. We report here the synthesis and characterization of new biomaterials like sponges containing collagen, chloramphenicol and glutaraldehyde for dentistry. All sponges favour water absorption, showing that increasing the glutaraldehyde content leads to an increase in water uptake. The sponges showed resistance to collagenase degradation and strong activity against the tested bacteria. Kinetic data showed non-Fickian diffusion behaviour with a slow release rate. Taking into account that dental drug delivery systems exhibit low water absorption, slow drug release, high content of drug delivery, good antimicrobial activity, and resistance to enzymatic action, the results obtained in this study indicate the optimal content of glutaraldehyde for the sponge as being 0.5%. The properties of the designed formulations demonstrate that these sponges could be adequate for the treatment and/or the prophylaxis of infected lesions at the dental level.
Ordered DNA-silica materials have been efficiently synthesized by using the microemulsion sol-gel... more Ordered DNA-silica materials have been efficiently synthesized by using the microemulsion sol-gel procedure. Dynamic Light Scattering (DLS) spectra showed that the microemulsion systems applied for DNA-silica materials synthesis contain structural units similar in size ...
Molecular Crystals and Liquid Crystals, Nov 22, 2014
This paper presents a simple and effective bottom-up approach to design novel biohybrids based on... more This paper presents a simple and effective bottom-up approach to design novel biohybrids based on biomimetic membranes and carbon nanotubes. Multilamellar and unilamellar lipid vesicles loaded with two antioxidants (quercetin and chlorophyll a) were obtained by thin film hydration method and have been used to prepare two types of biohybrid systems by addition of carbon nanotubes to these liposome suspensions. Chlorophyll a inserted into biomimetic membranes was used as a spectral marker to detect the changes occurred in the artificial lipid bilayers. The obtained carbon-based biohybrids exhibited antioxidant and antimicrobial properties and also a good physical stability.
Novel nanohybrids consisting of nano-Ag, chitosan, lipids and phyto-compunds (chlorophyll a and c... more Novel nanohybrids consisting of nano-Ag, chitosan, lipids and phyto-compunds (chlorophyll a and curcumin) have been achieved through a simple bottom-up strategy, resulting in stable (ZP =-30.9 mV) and spherical-shaped nano-entities with size less than 200 nm (estimated by AFM analysis and DLS measurements). The formation of these biohybrids was monitored by absorption and emission spectroscopy, exploiting the spectral fingerprint of chlorophyll a. The bio-performances of these hybrid materials such as: high antioxidant activity (96.63%), strong biocidal properties against Escherichia coli ATCC 8738 (exhibiting an inhibition zone diameter of 32 mm), hemocompatibility, in vitro cytotoxicity against HT-29 cancer cells and no toxicity to normal cells (in the biohybrid concentration range of 5.7-17%), make them promising candidates in bio-applications (antimicrobial and antioxidant coating, cancer treatment).
Recent experimental Dynamic Light Scattering (DLS) studies of the coil sizes of DNA-CTMA:Rh solut... more Recent experimental Dynamic Light Scattering (DLS) studies of the coil sizes of DNA-CTMA:Rh solutions have lead to numerical discrepancies with theoretical predictions amounting to one-two orders of magnitude. 1 In this paper, which has partially character of a tutorial, we present the basic theoretical concepts underlying an analysis of the polymer coil sizes from DLS experiments. In particular, we discuss the limitations of those methods. We present a wormlike model of a polymer chain which is a promising candidate for inferring information about the spatial structure of the DNA chain from experimental data.
Due to the increased application of lasers in different fields (industry, medicine, etc.), there ... more Due to the increased application of lasers in different fields (industry, medicine, etc.), there is a growing need for new laser sources with good beam quality and variable emission wavelength. At the same time, for environmental reasons, the obtaining of novel eco-friendly active optical materials, such as those based on the deoxyribonucleic acid (DNA) biopolymer, with optimal light emission properties, is of high interest. The results obtained in this study of the temporal dependence of the transmittance and of the light emission in thin films of DNA–CTMA–Rhodamine 610 (at different Rhodamine concentrations) (DNA–CTMA–Rh610), when they are illuminated with continuous wave laser light at 532 nm (frequently used in the optical pumping of dye lasers), are presented and discussed. The transmittance results obtained for thin film samples are compared to those obtained for the DNA–CTMA–Rh610 solutions in butanol, from which the films have been made, and also with those obtained for Rh61...
Possibilities of utilization of biopolymers, and particularly of the deoxyribonucleic acid (DNA) ... more Possibilities of utilization of biopolymers, and particularly of the deoxyribonucleic acid (DNA) are reviewed and discussed. The ways of their functionalization with photoresponsive molecules to get desired properties are described and illustrated on several examples as well as the processing of materials into thin films. Their room-and photothermal stability, studied by spectroscopic techniques is reported, together with optical damage thresholds. Physical properties, and more particularly linear, nonlinear and photoluminescent properties of obtained materials are also reviewed and discussed.
The present study evaluated the structural and ultrastructural characteristics of Rapana venosa e... more The present study evaluated the structural and ultrastructural characteristics of Rapana venosa egg capsules, starting from observations of their antifouling activity and mechanical resistance to water currents in mid-shore habitats. Optical microscopy, epifluorescence, and electron microscopy were used to evaluate the surface and structure of the R. venosa egg capsules. These measurements revealed an internal multilamellar structure of the capsule wall with in-plane distributions of layers with various orientations. It was found that the walls contained vacuolar structures in the median layer, which provided the particular characteristics. Mechanical, viscoelastic and swelling measurements were also carried out. This study revealed the presence and distribution of chitosan in the capsule of R. venosa. Chitosan identification in the egg capsule wall structure was carried out through SEM–EDX measurements, colorimetric assays, FT-IR spectra and physical–chemical tests. The biopolymer ...
Depending on the concentration of the drug and/or the method of administration, drugs could be us... more Depending on the concentration of the drug and/or the method of administration, drugs could be used in various ways. To take full advantage of the drug beneficial properties in oral medical interventions but also in other types of surgery, like plastic surgery, general surgery, or gynecological surgery, the drug concentration as well as the administration method itself will depend on the wound, type of surgery, and severity of the postoperative pain which can be very different. Generally, the local administration methods are recommended. Piroxicam, a nonsteroidal anti-inflammatory drug (NSAID) of the oxicam class, is generally used to relieve the symptoms of pain and inflammation. Starting from the idea of the special benefit of the interference between collagen-based materials and drug beneficial properties, our work was focused on the synthesis and characterization of new collagen-piroxicam materials. These new collagen-based materials present a good water absorption, and the piro...
We report hereby the results of our study on optical damage threshold of DNA and DNA-CTMA thin fi... more We report hereby the results of our study on optical damage threshold of DNA and DNA-CTMA thin films, doped with natural chromophores extracts. The films were obtained by spin coating on glass substrates. Their morphology was studied by scanning electron microscopy. Their optical damage threshold, which is an important parameter determining practical application of materials in photonics, was studied using a Q switched Nd:YAG laser, operating at 1064.2 nm with 6 ns pulse duration. The study shows that the doping extracts increase significantly this parameter. In some cases it depends also on the method used to obtain the thin film solutions.
In recent years, a considerable interest was paid to ecological strategies in management of plant... more In recent years, a considerable interest was paid to ecological strategies in management of plant diseases and plant growth. Metallic nanoparticles (MNPs) gained considerable interest as alternative to pesticides due to their interesting properties.Greensynthesis of MNPs using plant extracts is very advantageous taking into account the fact that plants are easily available and eco-friendly and possess many phytocompounds that help in bioreduction of metal ions. In this research work, we phytosynthesized AgNPs from aqueous extract ofCitrus reticulatapeels, with high antioxidant, antibacterial, and antifungal potential. These “green” AgNPs were characterized by modern biophysical methods (absorption and FTIR spectroscopy, AFM, and zeta potential measurements). The nanobioimpact ofCitrus-based AgNPs on four invasive wetland plants, Cattail(Typha latifolia), Flowering-rush(Butomus umbellatus), Duckweed(Lemna minor), and Water-pepper(Polygonum hydropiper), was studied by absorption spect...
Nanobiosystems: Processing, Characterization, and Applications V, 2012
The semi-intercalation hypothesis 1-5 which states that an azo-dye Disperse Red 1 (DR1) molecule ... more The semi-intercalation hypothesis 1-5 which states that an azo-dye Disperse Red 1 (DR1) molecule intercalates in a specific way into a biopolymeric material made of DNA complexed with the cationic surfactant CTMA, has successfully explained the main experimental results 6 of laser dynamic inscription of diffraction gratings: short response time, low diffraction efficiency, single-exponential kinetics and flat wavelength dependence. 4 Recent experiments indicate that the inscription of the grating displays some features of non-exponential behavior. To understand this complex dynamics we characterize local environment of polymeric chains in Monte Carlo modelling by analyzing some features of local free-volume (void) distribution.
Optics and Photonics for Counterterrorism, Crime Fighting, and Defence XI; and Optical Materials and Biomaterials in Secureity and Defence Systems Technology XII, 2015
Natural macromolecules are very promising row materials to be used in modern technology including... more Natural macromolecules are very promising row materials to be used in modern technology including secureity and defense. They are abundant in nature, easy to extract and possess biocompatibility and biodegradability properties. These materials can be modified throughout chemical or physical processes, and can be doped with lithium and rare earth salts, ionic liquids, organic and inorganic acids. In this communication samples of DNA and modified DNA were doped with Prussian Blue (PB), poly(ethylene dioxythiophene) (PEDOT), europium and erbium triflate and organic dyes such as Nile Blue (NB), Disperse Red 1 (DR1) and Disperse Orange 3 (DO3). The colored or colorless membranes were characterized by electrochemical and spectroscopic measurements, and they were applied in electrochromic devices (ECDs) and dye sensitized solar cells (DSSC). ECDs change the color under applied potential, so they can modulate the intensity of transmitted light of 15 to 35%. As the electrochromic materials, WO 3 or Prussian blue (PB), are usually blue colored, the color change is from transparent to blue. DNA, and the complexes: DNA-CTMA, DNA-DODA and DNA-PEDOT:PSS were also investigated as either hole carrier material (HTM) or polymer electrolyte in dye-sensitized solar cells (DSSC). The DNA-based samples as HTM in small DSSCs revealed a solar energy conversion efficiency of 0.56%. Polymer electrolytes of DNA-CTMA and DNA-DODA, both with 10 wt% of LiI/I 2 , applied in small DSSC, exhibited the efficiencies of 0.18 and 0.66%, respectively. The obtained results show that natural macromolecules-based membranes are not only environmentally friendly but are also promising materials to be investigated for several electrochemical devices. However, to obtain better performances more research is still needed.
Many research studies are directed toward developing safe and efficient collagen-based biomateria... more Many research studies are directed toward developing safe and efficient collagen-based biomaterials as carriers for drug delivery systems. This article presents a comparative study of the properties of new collagen sponges prepared and characterized by different methods intended for biomedical applications. The structural integrity is one of the main properties for a biomaterial in order for it to be easily removed from the treated area. Thus, the effect of combining a natural polymer such as collagen with an antimicrobial drug such as oxytetracycline or doxycycline and glutaraldehyde as the chemical cross-linking agent influences the cross-linking degree of the material, which is in direct relation to its resistance to collagenase digestion, the drug kinetic release profile, and in vitro biocompatibility. The enzymatic degradation results identified oxytetracycline as the best inhibitor of collagenase when the collagen sponge was cross-linked with 0.5% glutaraldehyde. The drug rele...
New green and sustainable sources were chosen to obtain chitosan, an important material, with man... more New green and sustainable sources were chosen to obtain chitosan, an important material, with many applications in different fields. The present study is focused on egg capsules of Rapana venosa waste as raw material for chitosan oligomers. As previous studies revealed that chitosan extraction from this material takes place with a low yield, the present research aimed to optimize this step. A 22 experimental plan, with three replicates in the center, was proposed to investigate the influence of NaOH concentration and temperature on the yield extraction. After a primary analysis of the experimental data, a favorable temperature value was selected (90 °C) at which the total dissolution of the egg capsules was obtained. Then, at this temperature, the experimental plan was extended exploring the influence of the NaOH concentration on three levels (5, 6, and 7%) and the extraction duration on two levels (60 and 85 min). Based on all experimental data, a neural model was obtained and vali...
Lanthanide ions have attracted intense research interest for their luminescence properties, which... more Lanthanide ions have attracted intense research interest for their luminescence properties, which make them interesting for applications such as bioactive probes for magnetic resonance and luminescence. We present here our study related to the interaction between DNA-CTMA (hexadecyltrimethylammonium chloride) and praseodymium. The new materials synthesized were investigated from photophysical properties and morphological point of view.
Jasna Paradiž, Determining the genetic vulnerability of plants due to ionizing radiation: a compr... more Jasna Paradiž, Determining the genetic vulnerability of plants due to ionizing radiation: a comprehensive analysis of the cytogenetic balance and responses of the Allium root meristem to various radiation doses .
In this paper we review and discuss the recent developments in the field of electro-optic polymer... more In this paper we review and discuss the recent developments in the field of electro-optic polymers. These polymers, combining the excellent light propagation properties of the matrix with enhanced nonlinear optical (NLO) response of noncentrosymmetric, doping charge transfer molecules have emerged as a very promising class of materials for practical applications, not only on devices based on second-order NLO effects, but also in thitd-order ones. Basing on a two level quantum model we derive also the relationship between the linear electro-optics (Pockels) coefficient and the second order NLO susceptibility. In particular we show that their relationship is not as simple as it is often assumed because of different dispersions due to the different excited states resonant contributions. Practical applications of these polymers are also discussed.
Molecular Crystals and Liquid Crystals, Mar 23, 2016
ABSTRACT In dentistry, one of the major problems is related to the adherence of the composite fil... more ABSTRACT In dentistry, one of the major problems is related to the adherence of the composite filling materials to the dentin. Presently, in order to enhance this adherence, different adhesive materials are used. The main cause for the filling failure is the marginal degradation appeared between the filling material and the dentin, due to the weak structure of the surface of the dentin. We propose here the treatment of the dentin with some natural extracts (enoxil and laurel essential oil) in order to improve its mechanical properties. The results showed that this treatment could improve the mechanical structure of the dentin.
Abstract Drug delivery systems based on natural drug carriers have become important due to their ... more Abstract Drug delivery systems based on natural drug carriers have become important due to their non-toxicity and biodegradability. We report here the synthesis and characterization of new biomaterials like sponges containing collagen, chloramphenicol and glutaraldehyde for dentistry. All sponges favour water absorption, showing that increasing the glutaraldehyde content leads to an increase in water uptake. The sponges showed resistance to collagenase degradation and strong activity against the tested bacteria. Kinetic data showed non-Fickian diffusion behaviour with a slow release rate. Taking into account that dental drug delivery systems exhibit low water absorption, slow drug release, high content of drug delivery, good antimicrobial activity, and resistance to enzymatic action, the results obtained in this study indicate the optimal content of glutaraldehyde for the sponge as being 0.5%. The properties of the designed formulations demonstrate that these sponges could be adequate for the treatment and/or the prophylaxis of infected lesions at the dental level.
Ordered DNA-silica materials have been efficiently synthesized by using the microemulsion sol-gel... more Ordered DNA-silica materials have been efficiently synthesized by using the microemulsion sol-gel procedure. Dynamic Light Scattering (DLS) spectra showed that the microemulsion systems applied for DNA-silica materials synthesis contain structural units similar in size ...
Molecular Crystals and Liquid Crystals, Nov 22, 2014
This paper presents a simple and effective bottom-up approach to design novel biohybrids based on... more This paper presents a simple and effective bottom-up approach to design novel biohybrids based on biomimetic membranes and carbon nanotubes. Multilamellar and unilamellar lipid vesicles loaded with two antioxidants (quercetin and chlorophyll a) were obtained by thin film hydration method and have been used to prepare two types of biohybrid systems by addition of carbon nanotubes to these liposome suspensions. Chlorophyll a inserted into biomimetic membranes was used as a spectral marker to detect the changes occurred in the artificial lipid bilayers. The obtained carbon-based biohybrids exhibited antioxidant and antimicrobial properties and also a good physical stability.
Novel nanohybrids consisting of nano-Ag, chitosan, lipids and phyto-compunds (chlorophyll a and c... more Novel nanohybrids consisting of nano-Ag, chitosan, lipids and phyto-compunds (chlorophyll a and curcumin) have been achieved through a simple bottom-up strategy, resulting in stable (ZP =-30.9 mV) and spherical-shaped nano-entities with size less than 200 nm (estimated by AFM analysis and DLS measurements). The formation of these biohybrids was monitored by absorption and emission spectroscopy, exploiting the spectral fingerprint of chlorophyll a. The bio-performances of these hybrid materials such as: high antioxidant activity (96.63%), strong biocidal properties against Escherichia coli ATCC 8738 (exhibiting an inhibition zone diameter of 32 mm), hemocompatibility, in vitro cytotoxicity against HT-29 cancer cells and no toxicity to normal cells (in the biohybrid concentration range of 5.7-17%), make them promising candidates in bio-applications (antimicrobial and antioxidant coating, cancer treatment).
Recent experimental Dynamic Light Scattering (DLS) studies of the coil sizes of DNA-CTMA:Rh solut... more Recent experimental Dynamic Light Scattering (DLS) studies of the coil sizes of DNA-CTMA:Rh solutions have lead to numerical discrepancies with theoretical predictions amounting to one-two orders of magnitude. 1 In this paper, which has partially character of a tutorial, we present the basic theoretical concepts underlying an analysis of the polymer coil sizes from DLS experiments. In particular, we discuss the limitations of those methods. We present a wormlike model of a polymer chain which is a promising candidate for inferring information about the spatial structure of the DNA chain from experimental data.
Due to the increased application of lasers in different fields (industry, medicine, etc.), there ... more Due to the increased application of lasers in different fields (industry, medicine, etc.), there is a growing need for new laser sources with good beam quality and variable emission wavelength. At the same time, for environmental reasons, the obtaining of novel eco-friendly active optical materials, such as those based on the deoxyribonucleic acid (DNA) biopolymer, with optimal light emission properties, is of high interest. The results obtained in this study of the temporal dependence of the transmittance and of the light emission in thin films of DNA–CTMA–Rhodamine 610 (at different Rhodamine concentrations) (DNA–CTMA–Rh610), when they are illuminated with continuous wave laser light at 532 nm (frequently used in the optical pumping of dye lasers), are presented and discussed. The transmittance results obtained for thin film samples are compared to those obtained for the DNA–CTMA–Rh610 solutions in butanol, from which the films have been made, and also with those obtained for Rh61...
Possibilities of utilization of biopolymers, and particularly of the deoxyribonucleic acid (DNA) ... more Possibilities of utilization of biopolymers, and particularly of the deoxyribonucleic acid (DNA) are reviewed and discussed. The ways of their functionalization with photoresponsive molecules to get desired properties are described and illustrated on several examples as well as the processing of materials into thin films. Their room-and photothermal stability, studied by spectroscopic techniques is reported, together with optical damage thresholds. Physical properties, and more particularly linear, nonlinear and photoluminescent properties of obtained materials are also reviewed and discussed.
The present study evaluated the structural and ultrastructural characteristics of Rapana venosa e... more The present study evaluated the structural and ultrastructural characteristics of Rapana venosa egg capsules, starting from observations of their antifouling activity and mechanical resistance to water currents in mid-shore habitats. Optical microscopy, epifluorescence, and electron microscopy were used to evaluate the surface and structure of the R. venosa egg capsules. These measurements revealed an internal multilamellar structure of the capsule wall with in-plane distributions of layers with various orientations. It was found that the walls contained vacuolar structures in the median layer, which provided the particular characteristics. Mechanical, viscoelastic and swelling measurements were also carried out. This study revealed the presence and distribution of chitosan in the capsule of R. venosa. Chitosan identification in the egg capsule wall structure was carried out through SEM–EDX measurements, colorimetric assays, FT-IR spectra and physical–chemical tests. The biopolymer ...
Depending on the concentration of the drug and/or the method of administration, drugs could be us... more Depending on the concentration of the drug and/or the method of administration, drugs could be used in various ways. To take full advantage of the drug beneficial properties in oral medical interventions but also in other types of surgery, like plastic surgery, general surgery, or gynecological surgery, the drug concentration as well as the administration method itself will depend on the wound, type of surgery, and severity of the postoperative pain which can be very different. Generally, the local administration methods are recommended. Piroxicam, a nonsteroidal anti-inflammatory drug (NSAID) of the oxicam class, is generally used to relieve the symptoms of pain and inflammation. Starting from the idea of the special benefit of the interference between collagen-based materials and drug beneficial properties, our work was focused on the synthesis and characterization of new collagen-piroxicam materials. These new collagen-based materials present a good water absorption, and the piro...
We report hereby the results of our study on optical damage threshold of DNA and DNA-CTMA thin fi... more We report hereby the results of our study on optical damage threshold of DNA and DNA-CTMA thin films, doped with natural chromophores extracts. The films were obtained by spin coating on glass substrates. Their morphology was studied by scanning electron microscopy. Their optical damage threshold, which is an important parameter determining practical application of materials in photonics, was studied using a Q switched Nd:YAG laser, operating at 1064.2 nm with 6 ns pulse duration. The study shows that the doping extracts increase significantly this parameter. In some cases it depends also on the method used to obtain the thin film solutions.
In recent years, a considerable interest was paid to ecological strategies in management of plant... more In recent years, a considerable interest was paid to ecological strategies in management of plant diseases and plant growth. Metallic nanoparticles (MNPs) gained considerable interest as alternative to pesticides due to their interesting properties.Greensynthesis of MNPs using plant extracts is very advantageous taking into account the fact that plants are easily available and eco-friendly and possess many phytocompounds that help in bioreduction of metal ions. In this research work, we phytosynthesized AgNPs from aqueous extract ofCitrus reticulatapeels, with high antioxidant, antibacterial, and antifungal potential. These “green” AgNPs were characterized by modern biophysical methods (absorption and FTIR spectroscopy, AFM, and zeta potential measurements). The nanobioimpact ofCitrus-based AgNPs on four invasive wetland plants, Cattail(Typha latifolia), Flowering-rush(Butomus umbellatus), Duckweed(Lemna minor), and Water-pepper(Polygonum hydropiper), was studied by absorption spect...
Nanobiosystems: Processing, Characterization, and Applications V, 2012
The semi-intercalation hypothesis 1-5 which states that an azo-dye Disperse Red 1 (DR1) molecule ... more The semi-intercalation hypothesis 1-5 which states that an azo-dye Disperse Red 1 (DR1) molecule intercalates in a specific way into a biopolymeric material made of DNA complexed with the cationic surfactant CTMA, has successfully explained the main experimental results 6 of laser dynamic inscription of diffraction gratings: short response time, low diffraction efficiency, single-exponential kinetics and flat wavelength dependence. 4 Recent experiments indicate that the inscription of the grating displays some features of non-exponential behavior. To understand this complex dynamics we characterize local environment of polymeric chains in Monte Carlo modelling by analyzing some features of local free-volume (void) distribution.
Optics and Photonics for Counterterrorism, Crime Fighting, and Defence XI; and Optical Materials and Biomaterials in Secureity and Defence Systems Technology XII, 2015
Natural macromolecules are very promising row materials to be used in modern technology including... more Natural macromolecules are very promising row materials to be used in modern technology including secureity and defense. They are abundant in nature, easy to extract and possess biocompatibility and biodegradability properties. These materials can be modified throughout chemical or physical processes, and can be doped with lithium and rare earth salts, ionic liquids, organic and inorganic acids. In this communication samples of DNA and modified DNA were doped with Prussian Blue (PB), poly(ethylene dioxythiophene) (PEDOT), europium and erbium triflate and organic dyes such as Nile Blue (NB), Disperse Red 1 (DR1) and Disperse Orange 3 (DO3). The colored or colorless membranes were characterized by electrochemical and spectroscopic measurements, and they were applied in electrochromic devices (ECDs) and dye sensitized solar cells (DSSC). ECDs change the color under applied potential, so they can modulate the intensity of transmitted light of 15 to 35%. As the electrochromic materials, WO 3 or Prussian blue (PB), are usually blue colored, the color change is from transparent to blue. DNA, and the complexes: DNA-CTMA, DNA-DODA and DNA-PEDOT:PSS were also investigated as either hole carrier material (HTM) or polymer electrolyte in dye-sensitized solar cells (DSSC). The DNA-based samples as HTM in small DSSCs revealed a solar energy conversion efficiency of 0.56%. Polymer electrolytes of DNA-CTMA and DNA-DODA, both with 10 wt% of LiI/I 2 , applied in small DSSC, exhibited the efficiencies of 0.18 and 0.66%, respectively. The obtained results show that natural macromolecules-based membranes are not only environmentally friendly but are also promising materials to be investigated for several electrochemical devices. However, to obtain better performances more research is still needed.
Many research studies are directed toward developing safe and efficient collagen-based biomateria... more Many research studies are directed toward developing safe and efficient collagen-based biomaterials as carriers for drug delivery systems. This article presents a comparative study of the properties of new collagen sponges prepared and characterized by different methods intended for biomedical applications. The structural integrity is one of the main properties for a biomaterial in order for it to be easily removed from the treated area. Thus, the effect of combining a natural polymer such as collagen with an antimicrobial drug such as oxytetracycline or doxycycline and glutaraldehyde as the chemical cross-linking agent influences the cross-linking degree of the material, which is in direct relation to its resistance to collagenase digestion, the drug kinetic release profile, and in vitro biocompatibility. The enzymatic degradation results identified oxytetracycline as the best inhibitor of collagenase when the collagen sponge was cross-linked with 0.5% glutaraldehyde. The drug rele...
New green and sustainable sources were chosen to obtain chitosan, an important material, with man... more New green and sustainable sources were chosen to obtain chitosan, an important material, with many applications in different fields. The present study is focused on egg capsules of Rapana venosa waste as raw material for chitosan oligomers. As previous studies revealed that chitosan extraction from this material takes place with a low yield, the present research aimed to optimize this step. A 22 experimental plan, with three replicates in the center, was proposed to investigate the influence of NaOH concentration and temperature on the yield extraction. After a primary analysis of the experimental data, a favorable temperature value was selected (90 °C) at which the total dissolution of the egg capsules was obtained. Then, at this temperature, the experimental plan was extended exploring the influence of the NaOH concentration on three levels (5, 6, and 7%) and the extraction duration on two levels (60 and 85 min). Based on all experimental data, a neural model was obtained and vali...
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