10 research outputs found
Slope <i>s</i> and y-axis intersections <i>l<sub>0</sub></i> for calibration curves established for typical measurement sessions.
<p>Slope <i>s</i> and y-axis intersections <i>l<sub>0</sub></i> for calibration curves established for typical measurement sessions.</p
Photograph of the special made Dewar WG-821-TMR-SPECIAL (labelled āBā) containing a 100 ĀµL tablet in a 8 mm precision bore Suprasil tube 513A-1PP-7SUP (labelled āAā).
<p>A Bruker 3122SHQE resonator is also shown in the figure indicating the position of the special made Dewar with the 100 ĀµL tablet inside the resonator. Both the Suprasil tube and Dewar are from Wilmad-LabGlas (Vineland, New Jersey, USA).</p
Table shows the initial results of quantification of ROS in rat myocardial tissue samples (first column) and the results of a repeated series of measurements after storage in ā80Ā°C during six month (second column).
<p>Third column show the difference between the two measurement sessions. (Estimated uncertainty Ā±10 ĀµM (kā=ā1)).</p
EPR peak-to-peak value as a function of [CPā¢] in calibration samples of CPā¢ solved in KHB (circles).
<p>Calibration curve calculated using least-squares-method for the shown example was deduced to <i>s</i>ā=ā0.03436 ĀµM<sup>ā1</sup> (slope of calibration curve) and <i>l<sub>0</sub></i>ā=ā0.24179 (the y-axis intersection of the calibration curve (dimensionless)).</p
EPR spectra for CPā¢ (grey line) and CMā¢ (black line) obtained at 150 K using the parameters for quantitative EPR.
<p>For clarity only the central part of the spectra is shown and EPR spectra was normalised for equal signal intensity.</p
Photophysical and DFT Characterization of Novel Pt(II)-Coupled 2,5-Diaryloxazoles for Nonlinear Optical Absorption
Several new bis-phosphine platinumĀ(II) complexes with
2,5-diaryl-substituted
oxazole-containing alkyne ligands have been synthesized and optically
characterized in solution. Measurements of nonlinear absorption showed
strong attenuation of laser light at 532 and 600 nm. The light absorption
of the Pt complexes was shifted from the near-UV region for the ground
state to the red region for the excited triplet state, and was associated
with large extinction coefficients. The optical limiting effect can
be explained by tripletātriplet excited state absorption in
conjunction with fast excited singletāto-triplet intersystem
crossing and slow tripletāto-ground-state decay, in comparison
with the pulse length of the laser. DFT calculations show good predictability
of the S<sub>0</sub>āS<sub>1</sub> and S<sub>0</sub>āT<sub>1</sub> energy gaps and offer insight into the interaction strength
between Pt and the alkyne ligands. The use of this type of ligand,
with weak absorption for the PtĀ(II) complexes in the visual wavelength
range as a key feature, enables the possibility to further improve
these molecular systems for nonlinear absorption applications
Toward a Molecular Understanding of the Detection of Amyloid Proteins with Flexible Conjugated Oligothiophenes
Molecular and electronic structures
and optical absorption properties
of oligothiophenes used for spectral assignment of amyloid deposits
have been investigated for a family of probes known as luminescent
conjugated oligothiophenes (LCOs). Theoretical absorption spectra
have been determined using conformational averaging, combining classical
molecular dynamics (MD) simulations with quantum mechanical/molecular
mechanics (QM/MM) time-dependent density functional theory (TD-DFT)
spectrum calculations. Theoretical absorption spectra are in excellent
agreement with experiments, showing average errors below 5 nm for
absorption maxima. To couple observed properties to molecular structures,
a measure of planarity is defined, revealing a strong correlation
between the transition wavelength of the first and dominating electronically
excited state and dihedral rotations. It is shown that from this correlation,
predictions can be made of the absorption properties of probes based
only on information from MD trajectories. We show experimentally that
red shifts observed in the excitation maxima of LCOs when bound to
amyloid protein aggregates are also evident in absorption spectra.
We predict that these red shifts are due to conformational restriction
of the LCO in a protein binding pocket, causing a planarization of
the conjugated backbone. On the basis of our studies of planarity,
it is shown that such shifts are both possible and realistic
Silica Hybrid SolāGel Materials with Unusually High Concentration of PtāOrganic Molecular Guests: Studies of Luminescence and Nonlinear Absorption of Light
The development of new photonic materials is a key step
toward
improvement of existing optical devices and for the preparation of
a new generation of systems. Therefore synthesis of photonic hybrid
materials with a thorough understanding and control of the microstructure-to-properties
relationships is crucial. In this perspective, a new preparation method
based on fast gelation reactions using simple dispersion of dyes without
strong covalent bonding between dye and matrix has been developed.
This new solāgel method is demonstrated through synthesis of
monolithic siloxane-based hybrid materials highly doped by various
platinumĀ(II) acetylide derivatives. Concentrations of the chromophores
as high as 400 mM were obtained and resulted in unprecedented optical
power limiting (OPL) performance at 532 nm of the surface-polished
solids. Static and time-resolved photoluminescence of the prepared
hybrid materials were consistent with both OPL data and previous studies
of similar PtĀ(II) compounds in solution. The impacts of the microstructure
and the chemical composition of the matrix on the spectroscopic properties,
are discussed
Evidence for Age-Dependent <i>in Vivo</i> Conformational Rearrangement within AĪ² Amyloid Deposits
Deposition
of aggregated AĪ² peptide in the brain is one of the major hallmarks
of Alzheimerās disease. Using a combination of two structurally
different, but related, hypersensitive fluorescent amyloid markers,
LCOs, reporting on separate ultrastructural elements, we show that
conformational rearrangement occurs within AĪ² plaques of transgenic
mouse models as the animals age. This important mechanistic insight
should aid the design and evaluation of experiments currently using
plaque load as readout
Evidence for Age-Dependent <i>in Vivo</i> Conformational Rearrangement within AĪ² Amyloid Deposits
Deposition
of aggregated AĪ² peptide in the brain is one of the major hallmarks
of Alzheimerās disease. Using a combination of two structurally
different, but related, hypersensitive fluorescent amyloid markers,
LCOs, reporting on separate ultrastructural elements, we show that
conformational rearrangement occurs within AĪ² plaques of transgenic
mouse models as the animals age. This important mechanistic insight
should aid the design and evaluation of experiments currently using
plaque load as readout