— The aim of this study has been devoted to the study of electrospun polymeric nanofiber mats tha... more — The aim of this study has been devoted to the study of electrospun polymeric nanofiber mats that can be potentially used in active packaging. A previous characterization of the PVA solutions was carried out. Thus, density, electrical conductivity and viscosity have been measured as a function of PVA concentration (0, 4, 7 and 10% w/w). Subsequently, a standard electrospinning process was carried out. The fibber diameter was determined by analyzing high-resolution images from Scanning Electron Microscopy (SEM) using Image J software. Moreover, a characterization of tensile properties (by means of DMA) and vapour sorption capacity of PVA-based nanofiber mats was performed. In addition, water-soluble compounds were incorporated into electrospun nanofiber mats. Although they may induce marked changes in morphology, their incorporation may lead to marked improvements in techno-functional properties. Thus, addition of Sodium Carbonate (SC) involves occurrence of beads, due to the increase in electrostatic charges, whereas Citric Acid (CA) induce an increase in fibber size, related to a loss of solvent evaporation efficiency. However, both compounds significantly enhance water vapour absorption capacity.
Journal of the Science of Food and Agriculture, 2015
The incorporation of natural biocides agents into protein-based bioplastics, a source for biodegr... more The incorporation of natural biocides agents into protein-based bioplastics, a source for biodegradable polymeric materials, manufactured by thermo-mechanical method is a way to contribute to sustainable food packaging industry. This study assesses the antimicrobial activity of ten different biocides incorporated into wheat gluten-based bioplastics. Additionally, the effect that formulation, processing, and further thermal treatments exert on the thermo-mechanical properties, water absorption characteristics and rheological behaviour of these materials is studied. Bioplastics containing six of the ten examined bioactive agents have demonstrated suitable antimicrobial activity at 37°C after their incorporation into the bioplastic. Moreover, the essential oils are able to create an antimicrobial atmosphere within Petri dish. Depending on the selected biocide, its addition may alter the bioplastics protein network in a different extent, which leads to materials exhibiting less water uptake and different rheological and thermo-mechanical behaviours.
The role of Chlamydia pneumoniae in respiratory infections is controversial. Seroepidemiological ... more The role of Chlamydia pneumoniae in respiratory infections is controversial. Seroepidemiological studies in different countries have shown an incidence of around 50% of previous contact, whereas prospective studies only in the USA have detected 6–10% of C. pneumoniae in community acquired pneumonias; in a similar Swedish study no cases were detected. There have been no descriptions of this Chlamydia in
The journal of physical chemistry letters, Jan 9, 2015
Mismatch of current (I)-voltage (V) curves with respect to the scan direction, so-called I-V hyst... more Mismatch of current (I)-voltage (V) curves with respect to the scan direction, so-called I-V hysteresis, raises critical issue in MAPbI3 (MA = CH3NH3) perovskite solar cell. Although ferroelectric and/or ion migration has been proposed as a basis for the hysteresis, origin of hysteresis has not been apparently unraveled. We report here on the origin of I-V hysteresis of perovskite solar cell that was systematically evaluated by the interface-dependent electrode polarizations. Frequency (f)-dependent capacitance (C) revealed that the normal planar structure with the TiO2/MAPbI3/spiro-MeOTAD configuration showed most significant I-V hysteresis along with highest capacitance (10-2 F/cm2) among the studied cell configurations. Substantial reduction in capacitance to 10-3 F/cm2 was observed upon replacing TiO2 with PCBM, indicative of the TiO2 layer being mainly responsible for the hysteresis. The capacitance was intensively reduced to 10-5 F/cm2 and C-f feature shifted to higher frequen...
Hybrid lead halide perovskites (PVKs) have emerged as novel materials for photovoltaics and have ... more Hybrid lead halide perovskites (PVKs) have emerged as novel materials for photovoltaics and have rapidly reached very large solar to electricity power conversion efficiencies. As occurring with other kind of solar technologies establishing the working energy-band diagram constitutes a primary goal for device physics analysis. Here, the macroscopic electrical field distribution is experimentally determined using capacitance-voltage and Kelvin probe techniques. Planar structures comprising CH3NH3PbI3−xClx PVK exhibit p-doping character and form a p-n heterojunction with n-doped TiO2 compact layers. Depletion width at equilibrium within the PVK bulk has an extent about 300 nm (approximately half of the layer thickness), leaving as a consequence a significant neutral zone towards the anode contact. Charge collection properties are then accessible relying on the relative weight that diffusion and drift have as carrier transport driven forces.
Understanding working mechanisms of selective interfacial layers and the underlying energetics of... more Understanding working mechanisms of selective interfacial layers and the underlying energetics of the organic semiconductor/electrode interface is an issue of primary concern for improving organic solar cell technologies. TiO x interlayers are used here to tune the selectivity of the cathode contact to electrons by controlled UV-light activation. The S-shaped kink observed for deactivated titania interlayers completely disappears after 2 min of UV-light exposure yielding high fill factor (≈60%) and adequate efficiencies. UV-light activation of complete cells alters the work function of the oxide that decreases about 650 mV as observed by Kelvin probe measurements. Capacitive techniques reveals a light-intensity dependent shift in flat-band voltage of up to 1.2 V under 1 sun illumination (without UV) in the case of deactivated TiO x interlayers. An increase in the magnitude of the light-modulated dipole present at the oxide layer accounts for that voltage shift. Although the sign of ...
In this work efficiency of semitransparent Organic photovoltaic (OPV) devices to be used for low ... more In this work efficiency of semitransparent Organic photovoltaic (OPV) devices to be used for low intensity applications is investigated as a function of the processing conditions. It is observed that a thermal treatment of the organic layer induces fullerene migration towards the active layer/air interface. This physical process gives rise to different vertical segregation profile of donor and acceptor molecules. Once the back contact is deposited the amount of fullerene covering the surface will determine the contact selectivity and leakage current of the device. Control of this leakage current may not be essential for devices fabricated for high illumination conditions applications. However, devices to be used under low illumination conditions may be highly influenced by the presence of this parasitic dark current which flows in the opposite direction to photogenerated current. At the proximity of the contacts the vertical segregation profile is inferred from optical and electrica...
The present paper demonstrates the possibility of replacing indium-tin oxide (ITO) with heavily b... more The present paper demonstrates the possibility of replacing indium-tin oxide (ITO) with heavily boron-doped diamond (BDD). Plasma Enhanced Chemically Vapor Deposited BDDs layers of various thicknesses were prepared containing various boron concentrations in a gas phase. The dependence of the above-mentioned parameters on the optical and electrical properties of each BDD was studied in order to achieve optimal conditions for the effective application of diamond electrodes in organic electronics as a replacement for ITO. Bulk-heterojunction polymer-fullerene organic solar cells were fabricated to test the potency of BDD application in photovoltaic devices. The obtained results demonstrated the possibility of the aforementioned application. Even though the efficiency of BDD-based devices is lower compared to those using regular ITO-based architecture, the relevant issues were explained.
ABSTRACT The purpose of recent developments of profilometry by using white light interferometry i... more ABSTRACT The purpose of recent developments of profilometry by using white light interferometry is to provide new tools for the analysis of rough samples which when studied by monochromatic phase-shifting interferometry, may cause phase calculation ambiguities. The usual way to perform depth measurements by white light interferometry is to analyze the coherence-limited interference fringes while the optical path difference is scanned. The method proposed here does not use optical path difference scanning. A spectroscopic device is used instead to separate the interference intensities associated to each spectral component of the light source. Phase variations due to wavelength change are proportional to the optical path difference and allows depth measurement to be performed without axial scanning. The profile of one line of the inspected sample is obtained from only one 2D interferogram. In this 2D interferogram one direction corresponds to the inspected direction of the surface while the other one is the chromatic axis which allows phase to change with wavelength. Experimental results show the ability of the proposed method to obtain the profile of 1D surface with nanometric resolution.
Biology, Conservation and Sustainable Development of Sturgeons, 2009
We review the anatomic development of the sturgeon’s (Acipenser naccarii) heart. Attention has be... more We review the anatomic development of the sturgeon’s (Acipenser naccarii) heart. Attention has been focussed on the main developmental events that take place during the embryonic and early post-hatching periods. The study examines identification of the early heart tube, cardiac loop formation, and the transformation of the tubular heart into a multi-chambered organ in a temporal sequence. Also included are
— The aim of this study has been devoted to the study of electrospun polymeric nanofiber mats tha... more — The aim of this study has been devoted to the study of electrospun polymeric nanofiber mats that can be potentially used in active packaging. A previous characterization of the PVA solutions was carried out. Thus, density, electrical conductivity and viscosity have been measured as a function of PVA concentration (0, 4, 7 and 10% w/w). Subsequently, a standard electrospinning process was carried out. The fibber diameter was determined by analyzing high-resolution images from Scanning Electron Microscopy (SEM) using Image J software. Moreover, a characterization of tensile properties (by means of DMA) and vapour sorption capacity of PVA-based nanofiber mats was performed. In addition, water-soluble compounds were incorporated into electrospun nanofiber mats. Although they may induce marked changes in morphology, their incorporation may lead to marked improvements in techno-functional properties. Thus, addition of Sodium Carbonate (SC) involves occurrence of beads, due to the increase in electrostatic charges, whereas Citric Acid (CA) induce an increase in fibber size, related to a loss of solvent evaporation efficiency. However, both compounds significantly enhance water vapour absorption capacity.
Journal of the Science of Food and Agriculture, 2015
The incorporation of natural biocides agents into protein-based bioplastics, a source for biodegr... more The incorporation of natural biocides agents into protein-based bioplastics, a source for biodegradable polymeric materials, manufactured by thermo-mechanical method is a way to contribute to sustainable food packaging industry. This study assesses the antimicrobial activity of ten different biocides incorporated into wheat gluten-based bioplastics. Additionally, the effect that formulation, processing, and further thermal treatments exert on the thermo-mechanical properties, water absorption characteristics and rheological behaviour of these materials is studied. Bioplastics containing six of the ten examined bioactive agents have demonstrated suitable antimicrobial activity at 37°C after their incorporation into the bioplastic. Moreover, the essential oils are able to create an antimicrobial atmosphere within Petri dish. Depending on the selected biocide, its addition may alter the bioplastics protein network in a different extent, which leads to materials exhibiting less water uptake and different rheological and thermo-mechanical behaviours.
The role of Chlamydia pneumoniae in respiratory infections is controversial. Seroepidemiological ... more The role of Chlamydia pneumoniae in respiratory infections is controversial. Seroepidemiological studies in different countries have shown an incidence of around 50% of previous contact, whereas prospective studies only in the USA have detected 6–10% of C. pneumoniae in community acquired pneumonias; in a similar Swedish study no cases were detected. There have been no descriptions of this Chlamydia in
The journal of physical chemistry letters, Jan 9, 2015
Mismatch of current (I)-voltage (V) curves with respect to the scan direction, so-called I-V hyst... more Mismatch of current (I)-voltage (V) curves with respect to the scan direction, so-called I-V hysteresis, raises critical issue in MAPbI3 (MA = CH3NH3) perovskite solar cell. Although ferroelectric and/or ion migration has been proposed as a basis for the hysteresis, origin of hysteresis has not been apparently unraveled. We report here on the origin of I-V hysteresis of perovskite solar cell that was systematically evaluated by the interface-dependent electrode polarizations. Frequency (f)-dependent capacitance (C) revealed that the normal planar structure with the TiO2/MAPbI3/spiro-MeOTAD configuration showed most significant I-V hysteresis along with highest capacitance (10-2 F/cm2) among the studied cell configurations. Substantial reduction in capacitance to 10-3 F/cm2 was observed upon replacing TiO2 with PCBM, indicative of the TiO2 layer being mainly responsible for the hysteresis. The capacitance was intensively reduced to 10-5 F/cm2 and C-f feature shifted to higher frequen...
Hybrid lead halide perovskites (PVKs) have emerged as novel materials for photovoltaics and have ... more Hybrid lead halide perovskites (PVKs) have emerged as novel materials for photovoltaics and have rapidly reached very large solar to electricity power conversion efficiencies. As occurring with other kind of solar technologies establishing the working energy-band diagram constitutes a primary goal for device physics analysis. Here, the macroscopic electrical field distribution is experimentally determined using capacitance-voltage and Kelvin probe techniques. Planar structures comprising CH3NH3PbI3−xClx PVK exhibit p-doping character and form a p-n heterojunction with n-doped TiO2 compact layers. Depletion width at equilibrium within the PVK bulk has an extent about 300 nm (approximately half of the layer thickness), leaving as a consequence a significant neutral zone towards the anode contact. Charge collection properties are then accessible relying on the relative weight that diffusion and drift have as carrier transport driven forces.
Understanding working mechanisms of selective interfacial layers and the underlying energetics of... more Understanding working mechanisms of selective interfacial layers and the underlying energetics of the organic semiconductor/electrode interface is an issue of primary concern for improving organic solar cell technologies. TiO x interlayers are used here to tune the selectivity of the cathode contact to electrons by controlled UV-light activation. The S-shaped kink observed for deactivated titania interlayers completely disappears after 2 min of UV-light exposure yielding high fill factor (≈60%) and adequate efficiencies. UV-light activation of complete cells alters the work function of the oxide that decreases about 650 mV as observed by Kelvin probe measurements. Capacitive techniques reveals a light-intensity dependent shift in flat-band voltage of up to 1.2 V under 1 sun illumination (without UV) in the case of deactivated TiO x interlayers. An increase in the magnitude of the light-modulated dipole present at the oxide layer accounts for that voltage shift. Although the sign of ...
In this work efficiency of semitransparent Organic photovoltaic (OPV) devices to be used for low ... more In this work efficiency of semitransparent Organic photovoltaic (OPV) devices to be used for low intensity applications is investigated as a function of the processing conditions. It is observed that a thermal treatment of the organic layer induces fullerene migration towards the active layer/air interface. This physical process gives rise to different vertical segregation profile of donor and acceptor molecules. Once the back contact is deposited the amount of fullerene covering the surface will determine the contact selectivity and leakage current of the device. Control of this leakage current may not be essential for devices fabricated for high illumination conditions applications. However, devices to be used under low illumination conditions may be highly influenced by the presence of this parasitic dark current which flows in the opposite direction to photogenerated current. At the proximity of the contacts the vertical segregation profile is inferred from optical and electrica...
The present paper demonstrates the possibility of replacing indium-tin oxide (ITO) with heavily b... more The present paper demonstrates the possibility of replacing indium-tin oxide (ITO) with heavily boron-doped diamond (BDD). Plasma Enhanced Chemically Vapor Deposited BDDs layers of various thicknesses were prepared containing various boron concentrations in a gas phase. The dependence of the above-mentioned parameters on the optical and electrical properties of each BDD was studied in order to achieve optimal conditions for the effective application of diamond electrodes in organic electronics as a replacement for ITO. Bulk-heterojunction polymer-fullerene organic solar cells were fabricated to test the potency of BDD application in photovoltaic devices. The obtained results demonstrated the possibility of the aforementioned application. Even though the efficiency of BDD-based devices is lower compared to those using regular ITO-based architecture, the relevant issues were explained.
ABSTRACT The purpose of recent developments of profilometry by using white light interferometry i... more ABSTRACT The purpose of recent developments of profilometry by using white light interferometry is to provide new tools for the analysis of rough samples which when studied by monochromatic phase-shifting interferometry, may cause phase calculation ambiguities. The usual way to perform depth measurements by white light interferometry is to analyze the coherence-limited interference fringes while the optical path difference is scanned. The method proposed here does not use optical path difference scanning. A spectroscopic device is used instead to separate the interference intensities associated to each spectral component of the light source. Phase variations due to wavelength change are proportional to the optical path difference and allows depth measurement to be performed without axial scanning. The profile of one line of the inspected sample is obtained from only one 2D interferogram. In this 2D interferogram one direction corresponds to the inspected direction of the surface while the other one is the chromatic axis which allows phase to change with wavelength. Experimental results show the ability of the proposed method to obtain the profile of 1D surface with nanometric resolution.
Biology, Conservation and Sustainable Development of Sturgeons, 2009
We review the anatomic development of the sturgeon’s (Acipenser naccarii) heart. Attention has be... more We review the anatomic development of the sturgeon’s (Acipenser naccarii) heart. Attention has been focussed on the main developmental events that take place during the embryonic and early post-hatching periods. The study examines identification of the early heart tube, cardiac loop formation, and the transformation of the tubular heart into a multi-chambered organ in a temporal sequence. Also included are
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Papers by Antonio Guerrero