Eduard Jane - Academia.edu (original) (raw)

Papers by Eduard Jane

Mechanical properties of glass fiber reinforced composite materials are affected by fiber sizing.... more Mechanical properties of glass fiber reinforced composite materials
are affected by fiber sizing. A complex film formation, based on silane
film and PVA/PVAc (polyvinyl alcohol/polyvinyl acetate) microspheres
on glass fiber surface is determined by means of (i) nano-scale by
using atomic force microscopy (AFM), and (ii) macro-scale by using
zeta potential. Silane strongly binds through the Si-O-Si bond to the
glass surface providing the attachment mechanism as a coupling
agent. The silane forms islands, homogeneous film, as well as empty
sites. The value of average roughness for silanized surface changes
to 6.5 nm from unsized glass surface with only 0.6 nm. The silane film
then vertically penetrates in a honeycomb fashion from the glass
surface through the deposited PVA/PVAc microspheres forming a
hexagonal close pack structure. The silane film not only penetrates,
but also deforms the spheres from a dispersion (600 nm) to a
ellipsoidal shape on the surface. The surface area value Sa,
represents an area of PVA/PVAc microspheres which are not effected
by the silane penetration, changes as 0.2, 0.08, and 0.03 μm2 and the
ellipsoids size are 320/570, 300/610, and 270/620 nm for silane
concentrations of 0, 3.8, and 7.2 μg/ml, respectively. The silane film
also moves PVA/PVAc microspheres in the process of the complex
film formation from the low silane concentration areas into the
complex film area providing enough silane to stabilize the structure.
The values of residual silane honeycomb structure hight Ha are 6.5
nm, 7 nm, and 12 nm for the silane concentrations of 3.8, 7.2, and
14.3 μg/ml, respectively. The pH dependent zeta potential results
suggest a specific role of the silane with effects on the glass fiber
surface and also on the PVA/PVAc microspheres. The unsized glass
fiber surface and the silane film have similar zeta potentials ranging
from -64 mV to -12 mV at the pH range of 10.5 and 3, respectively.
The zeta potentials for the PVA/PVAc microspheres on the glass fiber
surface and within the silane film significantly decrease and range
from -25 mV to -5 mV. The shapes of the pH dependent zeta
potentials are typically different in the case of silane in the pH range
from 7 to 4. A triple layer model is used to fit the unsized glass
surface and the silane film. The value of surface site density for ΓXglass
and ΓXsilane, where X states for Al-O-Si, differs by factor of 10-4
suggesting an effective coupling of the silane film. A soft layer model
is used to fit silane-PVA/PVAc complex film which is approximated
with four layers. Such a simplification and a compensation of the
microsphere shape approximate the relevant lengths as the layer of
silane with 10% of the total length (27 nm), the layer of first PVA shell
with 30% (81 nm), the layer of PVAc core with 30% (81 nm), and
again the layer of second PVA shell with 30% (81 nm). The coverage
simulation resulted in the value of 0.4, in accord with the assumption
of the low order coverage, and indeed it is supported by the AFM
scans. Correlating the results of AFM, and zeta potential shed some
light on the formation mechanism of the silane-PVA/PVAc complex
film.

Our aim is to doubly confine a molecule of coumarin C522 in a host–guest supramolecular complex w... more Our aim is to doubly confine a molecule of coumarin C522 in
a host–guest supramolecular complex with b-cyclodextrin in
a reverse sodium dioctyl sulfosuccinate (AOT) micelle using
nonpolar n-heptane and polar water solvents. Varying the volumes
of coumarin C522 and b-cyclodextrin dissolved in water
allows us to control the water-pool diameters of the reverse
micelle in n-heptane with values of w=3, 5, 10, 20, and 40,
where w is the ratio of water concentration to AOT concentration
in n-heptane. To study the fluorescence dynamics of coumarin
C522, the spectral steady-state and time-resolved dependences
are compared for the two systems coumarin C522-
(water)/AOT(n-heptane), denoted C522/micelle, and coumarin
C522/b-cyclodextrin(water)/AOT(n-heptane), referred to as
C522/CD/micelle. The formation of the supramolecular host–
guest complex CD–C522 is indicated by a blue shift, but in the
micelle, the shift is red. However, the values of the fluorescence
maxima at 520 and 515 nm are still way below the value
of 535 nm representing bulk water. The interpretation of the
red shift is based on two complementary processes. The first
one is the confinement of CD and C522 by the micelle water
pool and the second is the perturbation of the micelle by CD
and C522, resulting in an increase of the water polarity. The
fluorescence spectra of the C522/micelle and C522/CD/micelle
systems have maxima and shoulders. The shoulder intensities
at 440 nm, representing the C522 at n-heptane/AOT interface,
decrease as the w values decrease. This intensity shift suggests
that the small micelle provides a stronger confinement, and
the presence of CD shifts the equilibrium from n-heptane towards
the water pool even more. The fluorescence emission
maxima of the C522/micelle and C522/CD/micelle systems for
all w values clearly differentiate two trends for w=3–5, and
w=10–40, suggesting different interaction in the small and
large micelles. Moreover, these fluorescence maxima result in 7
and 13 nm differences for w=3 and w=5, respectively, and
provide the spectral evidence to differentiate the C522 confinement
in the C522/micelle and C522/CD/micelle systems as
an effect of the CD molecule, which might be interpreted as
a double confinement of C522 in CD within the micelle. The ultrafast
decay in the case of w=3 ranges from 9.5 to 16 ps,
with an average of 12.6 ps, in the case of the C522/micelle
system. For C522/CD/micelle, the ultrafast decay at w=3
ranges from 9 to 14.5 ps, with an average of 11.8 ps. Increasing
w values (from 10 to 40) result in a decrease of the ultrafast
decay values in both cases to an average value of about
6.5 ps. The ultrafast decays of 12.6 and 11.8 ps for C522/micelle
and C522/CD/micelle, respectively, are in the agreement with
the observed red shift, supporting a double confinement in
the C522/CD/micelle(w=3) system. The dynamics in the small
and large micelles clearly show two different trends. Two
slopes in the data are observed for w values of 3–5 and 10–40
in the steady-state and time-resolved data. The average ultrafast
lifetimes are determined to be 12.6 and 6.5 ps for the
small (w=3) and the large (w=40) micelles, respectively. To interpret
the experimental solvation dynamics, a simplified
model is proposed, and although the model involves
a number of parameters, it satisfactory fits the dynamics and
provides the gradient of permittivity in the ideal micelle for
free water located in the centre (60–80) and for bound water
(25–60). An attempt to map the fluorescence dynamics of the
doubly confined C522/CD/micelle system is presented for the
first time.

Journal of the American Ceramic Society, 2011

ABSTRACT Europium‐doped LaSi3N5 phosphor synthesized from LaSi/Si/Si3N4/Eu2O3 mixture by direct n... more ABSTRACT Europium‐doped LaSi3N5 phosphor synthesized from LaSi/Si/Si3N4/Eu2O3 mixture by direct nitridation at 1390°C and additional annealing at 1630°C for 3 h shows emissions in the green light region. With increasing europium content in the general formula La1‐z Euz Si3N5‐z O1.5z from z = 0.04 to 0.063 the emission intensity increases. The two maxima of the excitation band for the 6.3 mol% Eu‐doped LaSi3N5 are at ~4.0 and ~3.35 eV. First‐principles density‐functional theory (DFT) calculations are performed to enhance the understanding of the electronic structure of the stoichiometric LaSi3N5 and La/Eu and N/O substituted ternary nitrides. To mimic the realistic concentration of Eu and O the cell volume is expanded to the 2 × 1 × 2 super‐cell with 144 atoms. Electronic structure and band gaps are calculated using both the plain DFT and the hybrid functional. Three different doping schemes are investigated combining the La3+/Eu3+, La3+/□, La3+/Eu2+ substitutions in cation sites (□ = cation vacancy) and the N3−/O2− substitution in the framework. The La3+/Eu3+ substitution does not lead to a significant change of the gap. The La3+/Eu2+ substitution introduces a narrow band of Eu 4f‐states in the gap thus narrowing the band gap. The calculated value of ~3.23 eV by the hybrid functional is in reasonable agreement with experimental data.

ChemPhysChem, 2012

Our aim is to doubly confine a molecule of coumarin C522 in a host-guest supramolecular complex w... more Our aim is to doubly confine a molecule of coumarin C522 in a host-guest supramolecular complex with β-cyclodextrin in a reverse sodium dioctyl sulfosuccinate (AOT) micelle using nonpolar n-heptane and polar water solvents. Varying the volumes of coumarin C522 and β-cyclodextrin dissolved in water allows us to control the water-pool diameters of the reverse micelle in n-heptane with values of w=3, 5, 10, 20, and 40, where w is the ratio of water concentration to AOT concentration in n-heptane. To study the fluorescence dynamics of coumarin C522, the spectral steady-state and time-resolved dependences are compared for the two systems coumarin C522(water)/AOT(n-heptane), denoted C522/micelle, and coumarin C522/β-cyclodextrin(water)/AOT(n-heptane), referred to as C522/CD/micelle. The formation of the supramolecular host-guest complex CD-C522 is indicated by a blue shift, but in the micelle, the shift is red. However, the values of the fluorescence maxima at 520 and 515 nm are still way below the value of 535 nm representing bulk water. The interpretation of the red shift is based on two complementary processes. The first one is the confinement of CD and C522 by the micelle water pool and the second is the perturbation of the micelle by CD and C522, resulting in an increase of the water polarity. The fluorescence spectra of the C522/micelle and C522/CD/micelle systems have maxima and shoulders. The shoulder intensities at 440 nm, representing the C522 at n-heptane/AOT interface, decrease as the w values decrease. This intensity shift suggests that the small micelle provides a stronger confinement, and the presence of CD shifts the equilibrium from n-heptane towards the water pool even more. The fluorescence emission maxima of the C522/micelle and C522/CD/micelle systems for all w values clearly differentiate two trends for w=3-5, and w=10-40, suggesting different interaction in the small and large micelles. Moreover, these fluorescence maxima result in 7 and 13 nm differences for w=3 and w=5, respectively, and provide the spectral evidence to differentiate the C522 confinement in the C522/micelle and C522/CD/micelle systems as an effect of the CD molecule, which might be interpreted as a double confinement of C522 in CD within the micelle. The ultrafast decay in the case of w=3 ranges from 9.5 to 16 ps, with an average of 12.6 ps, in the case of the C522/micelle system. For C522/CD/micelle, the ultrafast decay at w=3 ranges from 9 to 14.5 ps, with an average of 11.8 ps. Increasing w values (from 10 to 40) result in a decrease of the ultrafast decay values in both cases to an average value of about 6.5 ps. The ultrafast decays of 12.6 and 11.8 ps for C522/micelle and C522/CD/micelle, respectively, are in the agreement with the observed red shift, supporting a double confinement in the C522/CD/micelle(w=3) system. The dynamics in the small and large micelles clearly show two different trends. Two slopes in the data are observed for w values of 3-5 and 10-40 in the steady-state and time-resolved data. The average ultrafast lifetimes are determined to be 12.6 and 6.5 ps for the small (w=3) and the large (w=40) micelles, respectively. To interpret the experimental solvation dynamics, a simplified model is proposed, and although the model involves a number of parameters, it satisfactory fits the dynamics and provides the gradient of permittivity in the ideal micelle for free water located in the centre (60-80) and for bound water (25-60). An attempt to map the fluorescence dynamics of the doubly confined C522/CD/micelle system is presented for the first time.

Mechanical properties of glass fiber reinforced composite materials are affected by fiber sizing.... more Mechanical properties of glass fiber reinforced composite materials
are affected by fiber sizing. A complex film formation, based on silane
film and PVA/PVAc (polyvinyl alcohol/polyvinyl acetate) microspheres
on glass fiber surface is determined by means of (i) nano-scale by
using atomic force microscopy (AFM), and (ii) macro-scale by using
zeta potential. Silane strongly binds through the Si-O-Si bond to the
glass surface providing the attachment mechanism as a coupling
agent. The silane forms islands, homogeneous film, as well as empty
sites. The value of average roughness for silanized surface changes
to 6.5 nm from unsized glass surface with only 0.6 nm. The silane film
then vertically penetrates in a honeycomb fashion from the glass
surface through the deposited PVA/PVAc microspheres forming a
hexagonal close pack structure. The silane film not only penetrates,
but also deforms the spheres from a dispersion (600 nm) to a
ellipsoidal shape on the surface. The surface area value Sa,
represents an area of PVA/PVAc microspheres which are not effected
by the silane penetration, changes as 0.2, 0.08, and 0.03 μm2 and the
ellipsoids size are 320/570, 300/610, and 270/620 nm for silane
concentrations of 0, 3.8, and 7.2 μg/ml, respectively. The silane film
also moves PVA/PVAc microspheres in the process of the complex
film formation from the low silane concentration areas into the
complex film area providing enough silane to stabilize the structure.
The values of residual silane honeycomb structure hight Ha are 6.5
nm, 7 nm, and 12 nm for the silane concentrations of 3.8, 7.2, and
14.3 μg/ml, respectively. The pH dependent zeta potential results
suggest a specific role of the silane with effects on the glass fiber
surface and also on the PVA/PVAc microspheres. The unsized glass
fiber surface and the silane film have similar zeta potentials ranging
from -64 mV to -12 mV at the pH range of 10.5 and 3, respectively.
The zeta potentials for the PVA/PVAc microspheres on the glass fiber
surface and within the silane film significantly decrease and range
from -25 mV to -5 mV. The shapes of the pH dependent zeta
potentials are typically different in the case of silane in the pH range
from 7 to 4. A triple layer model is used to fit the unsized glass
surface and the silane film. The value of surface site density for ΓXglass
and ΓXsilane, where X states for Al-O-Si, differs by factor of 10-4
suggesting an effective coupling of the silane film. A soft layer model
is used to fit silane-PVA/PVAc complex film which is approximated
with four layers. Such a simplification and a compensation of the
microsphere shape approximate the relevant lengths as the layer of
silane with 10% of the total length (27 nm), the layer of first PVA shell
with 30% (81 nm), the layer of PVAc core with 30% (81 nm), and
again the layer of second PVA shell with 30% (81 nm). The coverage
simulation resulted in the value of 0.4, in accord with the assumption
of the low order coverage, and indeed it is supported by the AFM
scans. Correlating the results of AFM, and zeta potential shed some
light on the formation mechanism of the silane-PVA/PVAc complex
film.

Our aim is to doubly confine a molecule of coumarin C522 in a host–guest supramolecular complex w... more Our aim is to doubly confine a molecule of coumarin C522 in
a host–guest supramolecular complex with b-cyclodextrin in
a reverse sodium dioctyl sulfosuccinate (AOT) micelle using
nonpolar n-heptane and polar water solvents. Varying the volumes
of coumarin C522 and b-cyclodextrin dissolved in water
allows us to control the water-pool diameters of the reverse
micelle in n-heptane with values of w=3, 5, 10, 20, and 40,
where w is the ratio of water concentration to AOT concentration
in n-heptane. To study the fluorescence dynamics of coumarin
C522, the spectral steady-state and time-resolved dependences
are compared for the two systems coumarin C522-
(water)/AOT(n-heptane), denoted C522/micelle, and coumarin
C522/b-cyclodextrin(water)/AOT(n-heptane), referred to as
C522/CD/micelle. The formation of the supramolecular host–
guest complex CD–C522 is indicated by a blue shift, but in the
micelle, the shift is red. However, the values of the fluorescence
maxima at 520 and 515 nm are still way below the value
of 535 nm representing bulk water. The interpretation of the
red shift is based on two complementary processes. The first
one is the confinement of CD and C522 by the micelle water
pool and the second is the perturbation of the micelle by CD
and C522, resulting in an increase of the water polarity. The
fluorescence spectra of the C522/micelle and C522/CD/micelle
systems have maxima and shoulders. The shoulder intensities
at 440 nm, representing the C522 at n-heptane/AOT interface,
decrease as the w values decrease. This intensity shift suggests
that the small micelle provides a stronger confinement, and
the presence of CD shifts the equilibrium from n-heptane towards
the water pool even more. The fluorescence emission
maxima of the C522/micelle and C522/CD/micelle systems for
all w values clearly differentiate two trends for w=3–5, and
w=10–40, suggesting different interaction in the small and
large micelles. Moreover, these fluorescence maxima result in 7
and 13 nm differences for w=3 and w=5, respectively, and
provide the spectral evidence to differentiate the C522 confinement
in the C522/micelle and C522/CD/micelle systems as
an effect of the CD molecule, which might be interpreted as
a double confinement of C522 in CD within the micelle. The ultrafast
decay in the case of w=3 ranges from 9.5 to 16 ps,
with an average of 12.6 ps, in the case of the C522/micelle
system. For C522/CD/micelle, the ultrafast decay at w=3
ranges from 9 to 14.5 ps, with an average of 11.8 ps. Increasing
w values (from 10 to 40) result in a decrease of the ultrafast
decay values in both cases to an average value of about
6.5 ps. The ultrafast decays of 12.6 and 11.8 ps for C522/micelle
and C522/CD/micelle, respectively, are in the agreement with
the observed red shift, supporting a double confinement in
the C522/CD/micelle(w=3) system. The dynamics in the small
and large micelles clearly show two different trends. Two
slopes in the data are observed for w values of 3–5 and 10–40
in the steady-state and time-resolved data. The average ultrafast
lifetimes are determined to be 12.6 and 6.5 ps for the
small (w=3) and the large (w=40) micelles, respectively. To interpret
the experimental solvation dynamics, a simplified
model is proposed, and although the model involves
a number of parameters, it satisfactory fits the dynamics and
provides the gradient of permittivity in the ideal micelle for
free water located in the centre (60–80) and for bound water
(25–60). An attempt to map the fluorescence dynamics of the
doubly confined C522/CD/micelle system is presented for the
first time.

Journal of the American Ceramic Society, 2011

ABSTRACT Europium‐doped LaSi3N5 phosphor synthesized from LaSi/Si/Si3N4/Eu2O3 mixture by direct n... more ABSTRACT Europium‐doped LaSi3N5 phosphor synthesized from LaSi/Si/Si3N4/Eu2O3 mixture by direct nitridation at 1390°C and additional annealing at 1630°C for 3 h shows emissions in the green light region. With increasing europium content in the general formula La1‐z Euz Si3N5‐z O1.5z from z = 0.04 to 0.063 the emission intensity increases. The two maxima of the excitation band for the 6.3 mol% Eu‐doped LaSi3N5 are at ~4.0 and ~3.35 eV. First‐principles density‐functional theory (DFT) calculations are performed to enhance the understanding of the electronic structure of the stoichiometric LaSi3N5 and La/Eu and N/O substituted ternary nitrides. To mimic the realistic concentration of Eu and O the cell volume is expanded to the 2 × 1 × 2 super‐cell with 144 atoms. Electronic structure and band gaps are calculated using both the plain DFT and the hybrid functional. Three different doping schemes are investigated combining the La3+/Eu3+, La3+/□, La3+/Eu2+ substitutions in cation sites (□ = cation vacancy) and the N3−/O2− substitution in the framework. The La3+/Eu3+ substitution does not lead to a significant change of the gap. The La3+/Eu2+ substitution introduces a narrow band of Eu 4f‐states in the gap thus narrowing the band gap. The calculated value of ~3.23 eV by the hybrid functional is in reasonable agreement with experimental data.

ChemPhysChem, 2012

Our aim is to doubly confine a molecule of coumarin C522 in a host-guest supramolecular complex w... more Our aim is to doubly confine a molecule of coumarin C522 in a host-guest supramolecular complex with β-cyclodextrin in a reverse sodium dioctyl sulfosuccinate (AOT) micelle using nonpolar n-heptane and polar water solvents. Varying the volumes of coumarin C522 and β-cyclodextrin dissolved in water allows us to control the water-pool diameters of the reverse micelle in n-heptane with values of w=3, 5, 10, 20, and 40, where w is the ratio of water concentration to AOT concentration in n-heptane. To study the fluorescence dynamics of coumarin C522, the spectral steady-state and time-resolved dependences are compared for the two systems coumarin C522(water)/AOT(n-heptane), denoted C522/micelle, and coumarin C522/β-cyclodextrin(water)/AOT(n-heptane), referred to as C522/CD/micelle. The formation of the supramolecular host-guest complex CD-C522 is indicated by a blue shift, but in the micelle, the shift is red. However, the values of the fluorescence maxima at 520 and 515 nm are still way below the value of 535 nm representing bulk water. The interpretation of the red shift is based on two complementary processes. The first one is the confinement of CD and C522 by the micelle water pool and the second is the perturbation of the micelle by CD and C522, resulting in an increase of the water polarity. The fluorescence spectra of the C522/micelle and C522/CD/micelle systems have maxima and shoulders. The shoulder intensities at 440 nm, representing the C522 at n-heptane/AOT interface, decrease as the w values decrease. This intensity shift suggests that the small micelle provides a stronger confinement, and the presence of CD shifts the equilibrium from n-heptane towards the water pool even more. The fluorescence emission maxima of the C522/micelle and C522/CD/micelle systems for all w values clearly differentiate two trends for w=3-5, and w=10-40, suggesting different interaction in the small and large micelles. Moreover, these fluorescence maxima result in 7 and 13 nm differences for w=3 and w=5, respectively, and provide the spectral evidence to differentiate the C522 confinement in the C522/micelle and C522/CD/micelle systems as an effect of the CD molecule, which might be interpreted as a double confinement of C522 in CD within the micelle. The ultrafast decay in the case of w=3 ranges from 9.5 to 16 ps, with an average of 12.6 ps, in the case of the C522/micelle system. For C522/CD/micelle, the ultrafast decay at w=3 ranges from 9 to 14.5 ps, with an average of 11.8 ps. Increasing w values (from 10 to 40) result in a decrease of the ultrafast decay values in both cases to an average value of about 6.5 ps. The ultrafast decays of 12.6 and 11.8 ps for C522/micelle and C522/CD/micelle, respectively, are in the agreement with the observed red shift, supporting a double confinement in the C522/CD/micelle(w=3) system. The dynamics in the small and large micelles clearly show two different trends. Two slopes in the data are observed for w values of 3-5 and 10-40 in the steady-state and time-resolved data. The average ultrafast lifetimes are determined to be 12.6 and 6.5 ps for the small (w=3) and the large (w=40) micelles, respectively. To interpret the experimental solvation dynamics, a simplified model is proposed, and although the model involves a number of parameters, it satisfactory fits the dynamics and provides the gradient of permittivity in the ideal micelle for free water located in the centre (60-80) and for bound water (25-60). An attempt to map the fluorescence dynamics of the doubly confined C522/CD/micelle system is presented for the first time.