499 research outputs found
Probabilistic Insurance
Probabilistic insurance is an insurance policy involving a small probability that the consumer will not be reimbursed. Survey data suggest that people dislike probabilistic insurance and demand more than a 20% reduction in the premium to compensate for a 1% default risk. While these preferences are intuitively appealing they are difficult to reconcile with expected utility theory. Under highly plausible assumptions about the utility function, willingness to pay for probabilistic insurance should be very close to willingness to pay for standard insurance less the default risk. However, the reluctance to buy probabilistic insurance is predicted by the weighting function of prospect theory. This finding highlights the potential role of the weighting function to explain insurance
In-depth structural characterization of the lignin fraction of a pine-derived pyrolysis oil
Pyrolytic lignin (PL) is the collective name of the water-insoluble fraction of pyrolysis oils produced from the fast pyrolysis of lignocellulosic biomass. As the name suggests, PL is composed by fragments derived from lignin, which is the largest natural source of aromatic carbon. Its valorization is of major importance for the realization of economically competitive biorefineries. Nonetheless, the valorization of PL is hindered by its complex structure, which makes the development of tailored strategies for its deconstruction into valuable compounds challenging. In this work, we provide an in-depth analysis of the structural composition of PL obtained from a commercially available pine-derived pyrolysis oil obtained at 500 °C (Empyro B.V., the Netherlands). Molecular weight distribution and thermal stability were accessed by GPC and TGA, respectively, and the monomers present in the PL (≈ 15 wt%) were identified and quantified by chromatographic analyses (GCxGC–FID, GCxGC/TOF–MS, GC–MS and HPLC). Together with FTIR, Py-GC–MS, TAN, elemental analysis and various advanced NMR techniques (13C NMR, 31P NMR, 19F NMR, HSQC NMR, HMBC NMR), structural features of the PL oligomers were elucidated, revealing a guaiacyl backbone linked by alkyl, ether, ester and carbonyl groups, with none of the typical native lignin linkages (i.e. β–O–4, β–β, β–5) present. Furthermore, 72.3 % of the oxygen content in PL could be assigned to specific motifs by the quantitative analyses performed, and oligomeric models were proposed based on the obtained information. We expect that this characterization work can support future research on the development of valorization pathways for PL, allowing the feasible conversion of this promising feedstock into valuable biobased products with a wide range of possible applications, e.g. fuels, materials and specialty chemicals
Fabrication of chromium oxide nanoparticles by laser-induced deposition from solution
We have successfully deposited well-dispersed nanoscale chromium oxide particles by laser-induced solution deposition (LISD) from solution with CrCl2 and organic solvents. The particles have narrow distributions about three sizes: 230, 350 and 400 nm and are uniform in composition and contain little contamination. We show that LISD is a new technique for producing nanoparticle chromium oxides with uniform composition, controllable size and high yield
Fabrication of chromium oxide nanoparticles by laser-induced deposition from solution
We have successfully deposited well-dispersed nanoscale chromium oxide particles by laser-induced solution deposition (LISD) from solution with CrCl2 and organic solvents. The particles have narrow distributions about three sizes: 230, 350 and 400 nm and are uniform in composition and contain little contamination. We show that LISD is a new technique for producing nanoparticle chromium oxides with uniform composition, controllable size and high yield
Hydrogen peroxide in exhaled air is increased in stable asthmatic children
Exhaled air condensate provides a noninvasive means of obtaining samples
from the lower respiratory tract. Hydrogen peroxide (H2O2) in exhaled air
has been proposed as a marker of airway inflammation. We hypothesized that
in stable asthmatic children the H2O2 concentration in exhaled air
condensate may be elevated as a result of airway inflammation. In a
cross-sectional study, 66 allergic asthmatic children (of whom, 41 were
treated with inhaled steroids) and 21 healthy controls exhaled through a
cold trap. The resulting condensate was examined fluorimetrically for the
presence of H2O2. All subjects were clinically stable, nonsmokers, without
infection. The median H2O2 level in the exhaled air condensate of the
asthmatic patients was significantly higher than in healthy controls (0.60
and 0.15 micromol, respectively; p<0.05), largely because of high values
in the stable asthmatic children who did not use anti-inflammatory
treatment (0.8 micromol; p<0.01 compared to controls). We conclude that
hydrogen peroxide is elevated in exhaled air condensate of children with
stable asthma, and may reflect airway inflammation
Decoherence of Atomic Gases in Largely Detuned Laser Fields
We study theoretically the decoherence of a gas of bosonic atoms induced by
the interaction with a largely detuned laser beam. It is shown that for a
standing laser beam decoherence coincides with the single-particle result. For
a running laser beam many-particle effects lead to significant modifications.Comment: 5 pages, 2 Figures, RevTe
The preparation and properties of lanthanum-promoted nickel-alumina catalysts:Structure of the precipitates
Precursors of La-promoted Ni-alumina catalysts have been prepared by precipitation from their nitrate solutions at pH 7 using solutions of NH4HCO3, Na2CO3 or K2CO3. The preparation was carried out either by coprecipitation from a mixed salt solution or by sequential precipitation of Al3+, La3+ and Ni2+ in succession. In the absence of promoter, the precipitate with Ni/Al ratio of 2.5 is of the pyroaurite structure and has the composition Ni5Al2(OH)14CO3.4H2O. Two types of lanthanum-containing precipitate were made in which either extra La was added (Ni/Al kept constant at 2.5) or the proportion Ni/(Al+La) was kept constant at 2.5. The majority of these precipitates were single compounds which also had the pyroaurite structure. At high La contents, the series in which La is added gives separation of the compounds La2O(CO3)2 and LaONO3 in addition to the layer structure; with the series in which the La is substituted for Al, all the samples appeared to have the pyroaurite structure, even one in which no Al was present. The sequential precipitation route yields smaller crystallites than does coprecipitation. Materials precipitated with NH4HCO3 in all cases contained NH4NO3 while those precipitated with Na2CO3 gave inclusion of NaNO3. In both cases, the presence of the nitrates causes a decrease of crystallinity of the layer compound. Potassium is not included in the precipitate in any of the samples examined. A model is presented for the structure of the lanthanum-containing precipitates
Near-Limb Zeeman and Hanle Diagnostics
"Weak" magnetic-field diagnostics in faint objects near the bright solar disk
are discussed in terms of the level of non-object signatures, in particular, of
the stray light in telescopes. Calculated dependencies of the stray light
caused by diffraction at the 0.5-, 1.6-, and 4-meter entrance aperture are
presented. The requirements for micro-roughness of refractive and reflective
primary optics are compared. Several methods for reducing the stray light (the
Lyot coronagraphic technique, multiple stages of apodizing in the focal and
exit pupil planes, apodizing in the entrance aperture plane with a special
mask), and reducing the random and systematic errors are noted. An acceptable
level of stray light in telescopes is estimated for the V-profile recording
with a signal-to-noise ratio greater than three. Prospects for the limb
chromosphere magnetic measurements are indicated.Comment: 11 pages, 3 figure
Hydrogen peroxide in exhaled air of healthy children: reference values
An increased content of hydrogen peroxide (H2O2), a marker of
inflammation, has been described in the condensate of exhaled air from
adults and children with inflammatory lung disorders, including asthma.
However, the normal range of [H2O2] in the exhaled air condensate from
healthy children has not been established. Therefore, the aim of this
study was to determine the reference range of exhaled [H2O2] in healthy
school-aged children. Ninety-three healthy nonsmoking children (48 female
and 45 male, mean age 10 yrs, range 8-13 yrs), with a negative history for
allergy, eczema or respiratory disease and with a normal lung function,
participated. Exhaled air condensate was examined fluorimetrically for the
presence of H2O2. In addition, the reproducibility of [H2O2] within
subjects and between days and the stability of [H2O2] during storage at
-20 degrees C were assessed. The median [H2O2] in the exhaled air
condensate of all children was 0.13 microM, with a 2.5-97.5% reference
range of <0.01-0.48 microM. No significant difference existed between
males and females. There was no correlation between exhaled [H2O2] and age
or lung function. Repeated [H2O2] measurements on 2 consecutive days
showed satisfactory within-subject reproducibility and [H2O2] in stored
samples remained stable for at least 1 month at -20 degrees C. In
conclusion, this study provides reference data for exhaled hydrogen
peroxide in a large group of healthy children. The observed levels were
lower than those reported previously for healthy adults and were
independent of age, sex and lung function
Parametric amplification of metric fluctuations through a bouncing phase
We clarify the properties of the behavior of classical cosmological
perturbations when the Universe experiences a bounce. This is done in the
simplest possible case for which gravity is described by general relativity and
the matter content has a single component, namely a scalar field in a closed
geometry. We show in particular that the spectrum of scalar perturbations can
be affected by the bounce in a way that may depend on the wave number, even in
the large scale limit. This may have important implications for string
motivated models of the early Universe.Comment: 17 pages, 12 figures, LaTeX-ReVTeX format, version to match Phys.
Rev.
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