The need to explain virgin olive oil (VOO) aroma descriptors by means of volatiles has raised interest in applying analytical techniques for trapping and quantitating volatiles. Static headspace ...sampling with solid phase microextraction (SPME) as trapping material is one of the most applied solutions for analyzing volatiles. The use of an internal standard and the determination of the response factors of the main volatiles seem to guarantee the correct determination of volatile concentrations in VOOs by SPME-GC/FID. This paper, however, shows that the competition phenomena between volatiles in their adsorption to the SPME fiber, inherent in static headspace sampling, may affect the quantitation. These phenomena are more noticeable in the particular case of highly odorant matrices, such as rancid and vinegary VOOs with high intensity of defect. The competition phenomena can modify the measurement sensitivity, which can be observed in volatile quantitation as well as in the recording of internal standard areas in different matrices. This paper analyzes the bias of the peak areas and concentrations of those volatiles that are markers for each sensory defect of VOOs (rancid, vinegary, musty, and fusty) when the intensity and complexity of aroma are increased. Of the 17 volatile markers studied in this work, 10 presented some anomalies in the quantitation in highly odorant matrices due the competition phenomena. However, quantitation was not affected in the concentration ranges at which each volatile marker is typically found in the defective oils they were characteristic of, validating their use as markers.
We consider a nonlinear Robin problem driven by a nonhomogeneous differential operator, with reaction which exhibits the competition of two Carathéodory terms. One is parametric,
(
p
-
1
)
-sublinear ...with a partially concave nonlinearity near zero. The other is
(
p
-
1
)
-superlinear and has almost critical growth. Exploiting the special geometry of the problem, we prove a bifurcation-type result, describing the changes in the set of positive solutions as the parameter
λ
>
0
varies.
We consider semilinear parametric Robin problems driven by the Laplacian plus an indefinite and unbounded potential. In the reaction we have two competing nonlinearities. However, the competition is ...different from the usual one in “concave-convex” problems. Using a combination of different tools we prove a multiplicity theorem producing seven nontrivial smooth solutions all with sign information (four of constant sign and three nodal).
In this paper, we prove the existence of weak heteroclinic solutions for a family of anisotropic difference equations under competition phenomena between parameters.
Modal behaviors of an InGaAsP-InP Fabry-Perot laser emitting in a long-wavelength region were experimentally examined. The authors had predicted theoretically that the mode-competition phenomena ...induce quasi-periodic hopping among several longitudinal modes, which reveal multimode-like output spectra as the time-averaged spectra in long-wavelength lasers. In this paper, experimental measured data of the time variations of photon number and their frequency spectra in addition to the longitudinal mode spectra are reported together with theoretically simulated results. The previous theoretical predictions were well proved by these experimental measurements.
Generating mechanism of the optical feedback noise in semiconductor lasers and whose suppressing manner by utilizing the self-pulsation laser or the high frequency superposition method are ...theoretically reviewed. Those mechanisms are characterized in terms of the mode competition phenomena among the internal cavity modes of the solitary laser and the external cavity modes which are built up by the optical feedback. Suppression of the feedback noise is understood as an effect to shift the operating point to more stable state by help of the modulated photons and electron densities in the laser.
Among plant‐parasitic nematodes (PPNs), the species Meloidogyne chitwoodi constitutes an important agricultural issue and is listed as a quarantine species in the EU. This study investigated whether ...PPN communities can affect the establishment and expansion of M. chitwoodi during a simulated introduction. An original experimental design was developed on potato in the glasshouse involving four PPN communities derived from a single natural one that was initially grown on different host plants. Meloidogyne chitwoodi was inoculated at two different densities (50 or 1000 second‐stage juveniles (J2) per pot). After 4 months, M. chitwoodi was more abundant in the community showing a low overall abundance of PPNs, decreased in the other PPN communities and failed to establish in five pots out of 80. Results showed that establishment – even starting from a very low inoculum – can occur in all communities even if indigenous PPNs in the community affect the expansion through interspecific competition. The reverse interaction was also observed as PPN taxa were generally less abundant in the 1000 M. chitwoodi J2 inoculation treatments. The proportion of M. chitwoodi males produced was higher in the community showing low overall PPN abundance, suggesting a strong sensitivity of M. chitwoodi to intraspecific competition. The presented results suggest that a low abundance of indigenous PPNs presents a higher risk of expansion of M. chitwoodi even if the introduced inoculum is low.
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