303 research outputs found
Novel solid-state emissive polymers and polymeric blends from a T-Shaped benzodifuran scaffold: A comparative study
Two novel polyimines were synthesized from a benzodifuran based diamino monomer and two dialdehydes bearing bulky groups and a flexible spacer. The polymers display tuned luminescence performance according to the presence of half-salen groups. The effect of the intramolecular bond on the emission properties were examined. Two model compounds, replicating the same emissive Schiff base cores, were synthetized. From the models, dye-doped blends in the fluorophore/matrix ratio, resembling the polymers, were produced. Amorphous thin films of the covalent polymers and the polymeric blends were obtained by spin-coating technique. The Photoluminescent (PL) response of the different macromolecular systems were qualitatively and quantitatively examined and compared
A highly water-soluble fluorescent and colorimetric pH probe
A new 5-(4-((2-(benzothiazole-2-carbonyl)hydrazono)methyl)-3-hydroxyphenoxy)N,N,N-trimethylpentan-1-aminium bromide (BTABr) fluorescent and colorimetric pH probe was easily synthesized by the condensation reaction of benzothiazole-2-carbohydrazide with 5-(4-formyl-3-hydroxyphenoxy)-N,N,N-trimethylpentan-1-aminium bromide. The benzothiazole moiety provided the emissive part of the molecule and the charged trimethyl amino group guaranteed outstanding solubility in water, for an organic molecule. pH titration experiments indicated that the probe is useful for monitoring acidic and alkaline solutions, turning reversibly in color/fluorescence just at a neutral pH value. Naked-eye colorimetric response was observed both in solution and in the solid state. In addition, the probe showed high stability and selectivity and large Stokes shifts. Because of these features, BTABr can potentially work as an on-off real-time pH sensor for intracellular pH imaging. The crystal structure of BTABr examined by single-crystal analysis showed a planar geometry of the molecule and confirmed the presence of a molecular stacking between molecules joined in a complex tridimensional hydrogen bonding pattern
High nonlinear optical response in 4-chlorothiazole-based azo dyes
Four azo dyes showing high nonlinear optical properties were prepared, based on a 4-chlorothiazole azo moiety functionalized with strong acceptor groups and/or further donor/acceptor groups along the conjugated backbone. The effects of the acceptors as well as the lateral donor/acceptor groups upon absorption properties, thermal stability and second order nonlinear optical activity were evaluated. © 2010 Elsevier Ltd. All rights reserved
Naphthalenone polyketides produced by Neofusicoccum parvum , a fungus associated with grapevine Botriosphaeria dieback
A strain of Neofusicoccum parvum isolated from declining vines was pathogenic to grapevine cultivar
Inzolia in Sicily. This strain produced some metabolites in liquid medium. Crude extract, through a bio-guided
purification process, yielded four naphthalenone polyketides. They were identified by comparison with spectroscopic data and optical proprieties reported in literature as: (3S, 4S)-7-ethyl-3,4,8-trihydroxy-6-methoxy-3,4-dihydro-1-(2H)-naphthalenone, (3S*, 4S*)-3,4-dihydro-3,4,8-trihydroxy-7-(1-hydroxyethyl)-6-methoxy-1-(2H)-naphthalenone, (4S)-3,4-dihydro-4,8-dihydroxy-1-(2H)-naphthalenone, named botryosphaerones D and A, isosclerone, respectively, and (3S*,4S*)-3,4,5-trihydroxy-1-tetralone (1-4). Phytotoxic activity of the isolated compounds (1-4) was tested on grapevine leaves at using the leaf puncture assay. All tested compounds were phytotoxic, with botryosphaerone D showing the greatest activity. The phytotoxic effects decreased when treated leaves were exposed to light. All of the metabolites did not show in vitro antifungal activity against Diplodia seriata, Lasiodiplodia mediterranea, Neofusicoccum vitifusiforme, or Phytophthora citrophthora. This is the first report of in vitro production of botryosphaerones D and A, and 3,4,5-trihydroxy-1-tetralone by N. parvum
Intense beam of metastable Muonium
Precision spectroscopy of the Muonium Lamb shift and fine structure requires
a robust source of 2S Muonium. To date, the beam-foil technique is the only
demonstrated method for creating such a beam in vacuum. Previous experiments
using this technique were statistics limited, and new measurements would
benefit tremendously from the efficient 2S production at a low energy muon
( keV) facility. Such a source of abundant low energy has
only become available in recent years, e.g. at the Low-Energy Muon beamline at
the Paul Scherrer Institute. Using this source, we report on the successful
creation of an intense, directed beam of metastable Muonium. We find that even
though the theoretical Muonium fraction is maximal in the low energy range of
keV, scattering by the foil and transport characteristics of the beamline
favor slightly higher energies of keV. We estimate that
an event detection rate of a few events per second for a future Lamb shift
measurement is feasible, enabling an increase in precision by two orders of
magnitude over previous determinations
On the determination of the interaction time of GeV neutrinos in large argon gas TPCs
Next-generation megawatt-scale neutrino beams open the way to studying
neutrino-nucleus scattering resorting, for the first time, to gaseous targets.
This could lead to deeper knowledge of neutrino cross sections in the energy
region between hundreds of MeV and a few GeV, of interest for the upcoming
generation of long-baseline neutrino oscillation experiments. The challenge is,
therefore, to accurately track and (especially) time the particles produced in
neutrino interactions in large and seamless volumes down to few-MeV energies.
We propose to accomplish this through an optically-read time projection chamber
(TPC) filled with high-pressure argon and equipped with both tracking and
timing functions. In this work, we present a detailed study of the time-tagging
capabilities of such a device, based on end-to-end optical simulations that
include the effect of photon propagation, photosensor response, dark-count rate
and pulse reconstruction. We show that the neutrino interaction time could be
reconstructed from the primary-scintillation signal with a precision in the
range 1--2.5~ns () for point-like deposits with energies down to 5~MeV,
and well below 1~ns for minimum-ionizing particle tracks. A discussion on
previous limitations towards such a detection technology, and how they can be
realistically overcome in the near future thanks to recent developments in the
field, is presented (particularly the strong scintillation yields recently
reported for Ar/CF mixtures). The performance presented in our analysis
seems to be well within reach of next-generation neutrino-oscillation
experiments through the instrumentation of the proposed TPC with conventional
reflective materials and a SiPM carpet behind a transparent cathode
High familial burden of cancer correlates with improved outcome from immunotherapy in patients with NSCLC independent of somatic DNA damage response gene status
Family history of cancer (FHC) is a hallmark of cancer risk and an independent predictor of outcome, albeit with uncertain biologic foundations. We previously showed that FHC-high patients experienced prolonged overall (OS) and progression-free survival (PFS) following PD-1/PD-L1 checkpoint inhibitors. To validate our findings in patients with NSCLC, we evaluated two multicenter cohorts of patients with metastatic NSCLC receiving either first-line pembrolizumab or chemotherapy. From each cohort, 607 patients were randomly case–control matched accounting for FHC, age, performance status, and disease burden. Compared to FHC-low/negative, FHC-high patients experienced longer OS (HR 0.67 [95% CI 0.46–0.95], p = 0.0281), PFS (HR 0.65 [95% CI 0.48–0.89]; p = 0.0074) and higher disease control rates (DCR, 86.4% vs 67.5%, p = 0.0096), within the pembrolizumab cohort. No significant associations were found between FHC and OS/PFS/DCR within the chemotherapy cohort. We explored the association between FHC and somatic DNA damage response (DDR) gene alterations as underlying mechanism to our findings in a parallel cohort of 118 NSCLC, 16.9% of whom were FHC-high. The prevalence of ≥ 1 somatic DDR gene mutation was 20% and 24.5% (p = 0.6684) in FHC-high vs. FHC-low/negative, with no differences in tumor mutational burden (6.0 vs. 7.6 Mut/Mb, p = 0.6018) and tumor cell PD-L1 expression. FHC-high status identifies NSCLC patients with improved outcomes from pembrolizumab but not chemotherapy, independent of somatic DDR gene status. Prospective studies evaluating FHC alongside germline genetic testing are warranted
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