ABSTRACT
In 2022 the BL Lac object S4 0954+65 underwent a major variability phase, reaching its historical maximum brightness in the optical and γ-ray bands. We present optical photometric and ...polarimetric data acquired by the Whole Earth Blazar Telescope (WEBT) Collaboration from 2022 April 6 to July 6. Many episodes of unprecedented fast variability were detected, implying an upper limit to the size of the emitting region as low as $10^{-4}$ parsec. The WEBT data show rapid variability in both the degree and angle of polarization. We analyse different models to explain the polarization behaviour in the framework of a twisting jet model, which assumes that the long-term trend of the flux is produced by variations in the emitting region viewing angle. All the models can reproduce the average trend of the polarization degree, and can account for its general anticorrelation with the flux, but the dispersion of the data requires the presence of intrinsic mechanisms, such as turbulence, shocks, or magnetic reconnection. The WEBT optical data are compared to γ-ray data from the Fermi satellite. These are analysed with both fixed and adaptive binning procedures. We show that the strong correlation between optical and γ-ray data without measurable delay assumes different slopes in faint and high brightness states, and this is compatible with a scenario where in faint states we mainly see the imprint of the geometrical effects, while in bright states the synchrotron self-Compton process dominates.
In 2022 the BL Lac object S4 0954+65 underwent a major variability phase,
reaching its historical maximum brightness in the optical and $\gamma$-ray
bands. We present optical photometric and ...polarimetric data acquired by the
Whole Earth Blazar Telescope (WEBT) Collaboration from 2022 April 6 to July 6.
Many episodes of unprecedented fast variability were detected, implying an
upper limit to the size of the emitting region as low as $10^{-4}$ parsec. The
WEBT data show rapid variability in both the degree and angle of polarization.
We analyse different models to explain the polarization behaviour in the
framework of a twisting jet model, which assumes that the long-term trend of
the flux is produced by variations in the emitting region viewing angle. All
the models can reproduce the average trend of the polarization degree, and can
account for its general anticorrelation with the flux, but the dispersion of
the data requires the presence of intrinsic mechanisms, such as turbulence,
shocks, or magnetic reconnection. The WEBT optical data are compared to
$\gamma$-ray data from the Fermi satellite. These are analysed with both fixed
and adaptive binning procedures. We show that the strong correlation between
optical and $\gamma$-ray data without measurable delay assumes different slopes
in faint and high brightness states, and this is compatible with a scenario
where in faint states we mainly see the imprint of the geometrical effects,
while in bright states the synchrotron self-Compton process dominates.
In 2022 the BL Lac object S4 0954+65 underwent a major variability phase, reaching its historical maximum brightness in the optical and \(\gamma\)-ray bands. We present optical photometric and ...polarimetric data acquired by the Whole Earth Blazar Telescope (WEBT) Collaboration from 2022 April 6 to July 6. Many episodes of unprecedented fast variability were detected, implying an upper limit to the size of the emitting region as low as \(10^{-4}\) parsec. The WEBT data show rapid variability in both the degree and angle of polarization. We analyse different models to explain the polarization behaviour in the framework of a twisting jet model, which assumes that the long-term trend of the flux is produced by variations in the emitting region viewing angle. All the models can reproduce the average trend of the polarization degree, and can account for its general anticorrelation with the flux, but the dispersion of the data requires the presence of intrinsic mechanisms, such as turbulence, shocks, or magnetic reconnection. The WEBT optical data are compared to \(\gamma\)-ray data from the Fermi satellite. These are analysed with both fixed and adaptive binning procedures. We show that the strong correlation between optical and \(\gamma\)-ray data without measurable delay assumes different slopes in faint and high brightness states, and this is compatible with a scenario where in faint states we mainly see the imprint of the geometrical effects, while in bright states the synchrotron self-Compton process dominates.
Common chemotherapeutic drugs exhibit no specificity for cancer cells and destroy simultaneously healthy cells exhibiting high toxicity and reduced efficacy. The use of nanotechnology, especially of ...drug delivery systems to the size of the nanoscale, provides rational drug design solutions. Such nanomaterials may have a range of desired characteristics (lack of toxicity, response to certain characteristics of the cancer cells, antimicrobial properties, specific activity, etc.) in order to achieve targeted cancer therapy. In this chapter, polymeric systems with core-shell structure are synthesized, characterized, and studied as potent drug delivery devices for targeted cancer therapy. These polymeric systems are based on natural polysaccharides like cellulose, chitosan, and their derivatives, in combination with synthetic polymer. Polymethylmethacrylate (PMMA) nanospheres are used as a core in order to coat the surface with multiple layers of polysaccharides via layer-by-layer deposition. This design is advantageous due to the use of water as the appropriate solvent. Fabricated polymeric carriers are characterized structurally by AT-IR spectroscopy and morphologically by transmission (TEM) and scanning electron microscopy (SEM). Finally, daunorubicin, an anticancer agent, was encapsulated as a drug model into the carriers.
1H NMR Saturation Transfer Difference (STD) experiments were applied to study the binding of aspirin and of an anti-inflammatory complex of Cu(I), namely Cu(tpp)(pmt)2 pmt = 2-mercaptopyrimidine), ...synthesized in an attempt to develop novel metallotherapeutic molecules. While aspirin showed only very weak binding, the complex Cu(tpp)(pmt)2 clearly favored binding to LOX-1. In silico docking experiments in LOX-1 showed that aspirin does only weakly bind to LOX-1, while the complex binds with high affinity. In addition, docking experiments and molecular dynamics (MD) simulations showed that the complex binds via hydrogen bonding (HB), to an allosteric site of LOX-1, revealing that this enzyme has more than one accessible site for complex metallotherapeutic molecules. When aspirin was added in the solution containing LOX and the complex Cu(tpp)(pmt)2, the former was shown to hinder the binding of the Cu complex significantly. This may be interpreted as the copper complex aiding the transfer of aspirin through an acid–base reaction at the LOX enzyme which subsequently blocks its binding.
An anti-inflammatory complex of Ag(I), namely Ag(tpp)
3
(asp)(dmf) tpp = triphenylphosphine, aspH = aspirin, dmf = N,N-dimethylformamide, was synthesized in an attempt to develop novel ...metallotherapeutic molecules. STD
1
H NMR experiments were used to examine if this complex binds to LOX-1. The
1
H NMR spectra in buffer Tris/D
2
O betrayed the existence of two complexes: the complex of aspirin and the complex of salicylic acid produced after deacetylation of aspirin. Nevertheless, the STD spectra showed that only the complex of salicylic acid is bound to the enzyme. Molecular docking and dynamics were used to complement our study. The complexes were stabilized inside a large LOX-1 cavity by establishing a network of hydrogen bonds and steric interactions. The complex formation with salicylic acid was more favorable. The in silico results provide a plausible explanation of the experimental results, which showed that only the complex with salicylic acid enters the binding cavity.
