989 research outputs found
Suitability of borago officinalis for minimal processing as fresh-cut produce
Borage (Borago offcinalis L.) is a wild vegetable appreciated as a folk medicine and for culinary preparations. The introduction of borage as a specialized cultivation would allow for the diversification of vegetable crops and would widen the offerings of raw and minimally processed leafy vegetables. Thus, the aim of the research was to evaluate the quality and shelf-life of fresh-cut borage stored at different temperatures. Borage plants were grown during the autumn-winter season and immediately minimally processed after harvest. Fresh-cut borage leaves packed in sealed bags were stored at 2 or 6 °C for 21 d. Weight loss, total soluble solids (TSS), titratable acidity (TA), ascorbic acid, nitrates, leaf color characteristics and overall quality were determined through the storage period. Borage plants were deemed suitable for minimal processing. Storage temperature significantly influenced the rate of quality loss. Borage leaves had an initial nitrate content of 329.3 mg kg-1 FW that was not affected by temperature or storage. TSS and TA were higher in leaves stored at 6 °C. TSS, TA and ascorbic acid content increased during storage. Minimally processed borage leaves stored at 2 °C had lower weight loss and leaf color modifications during storage and a longer shelf life than those stored at 6 °C, so were still marketable after 21 d of storage
The effect of butanol isomers on the formation of carbon particulate matter in fuel-rich premixed ethylene flames
Abstract The effect of the butanol isomers on carbon particulate matter formation was studied by substituting up to 20% of the total carbon of ethylene, fed to premixed flames with different equivalence ratios, with the four butanol isomers. Soot and condensed-phase nanostructures were tracked by means of particle size distribution (PSD) measurements and laser induced emission spectroscopy, namely fluorescence and incandescence. Butanol isomers, especially t-butanol, significantly reduced the total amount and the size of the soot particles, whereas a negligible effect was detected on condensed-phase nanostructures. PSDs were measured along with the aromaticity and functionalities of the carbon particulate matter thermophoretically sampled in the highest equivalence ratio condition. No significant differences were found among the different butanol isomers neither in the soot aggregate size, as measured by size exclusion chromatography, nor in the aromaticity, as evaluated by Raman and UV–vis spectroscopy, of the particulate matter. Conversely, FTIR analysis showed that carbon particulate matter produced from 1-butanol and t-butanol-doped flames contained larger amounts of oxygen in form of C = O, C–O–C and OH functionalities. However, most of the differences in the oxygen functionalities disappeared after dichloromethane (DCM) treatment, suggesting that these oxygenated moieties belong to the condensed-phase nanostructures, soluble in DCM, rather than to soot particles
Particle formation in premixed ethylene-benzene flames: An experimental and modeling study
Abstract In this work soot formation was studied in laminar premixed flames of binary ethylene-benzene mixtures varying throughout the composition range from pure ethylene to pure benzene keeping constant the equivalence ratio (φ = 2) and obtaining a very similar maximum temperature (Tmax around 1750 K). In such way, it was possible to study for the first time the effect of binary aliphatic-aromatic fuel mixtures composition on the sooting behavior in comparable combustion conditions. In-situ optical techniques (laser induced incandescence and fluorescence) and ex-situ particle size distribution (PSD) measured downstream of the flame front, as well as modeling by means of a multi-sectional method, were applied. PSD profiles showed that particles with sizes less than 10 nm decrease as benzene percentage in the feed mixture increases, disappearing for benzene percentages above 30%. Conversely, large aggregates grow towards sizes larger than 100 nm when benzene concentration is increased. A non-linear effect of the benzene content in the binary fuel mixture on soot particle concentration was observed by laser induced incandescence, and confirmed by the multi-sectional model. In particular soot formation was found to increase more than linear up to 50% then leveled off to reincrease linearly from 80% to 100%. On the contrary, particles smaller than 10 nm at the end of the flame rapidly decreased for benzene percentages larger than 30%. From reaction rate analysis, the formation of gas-phase polycyclic aromatic hydrocarbons (PAH) and high-molecular mass aromatics precursors was found to be significantly large already for fuel mixtures featured by low benzene amounts (from 10 up to 40–50%). The enhanced aromatic precursor formation, combined with the abundance of acetylene mainly coming from the dehydrogenation of ethylene as predominant component of the binary fuel mixture, appeared to be responsible for the non-linear effect of ethylene-benzene composition on particle formation, particularly significant up to 40–50% of benzene. This finding has a considerable importance as regards the exploitation of highly-aromatic fuels as well as to foresee the soot emission for effect of the aromatic presence in natural and synthetic fuels used in practical combustion systems
Experimental measurement of an effective temperature for jammed granular materials
A densely packed granular system is an example of an out-of-equilibrium
system in the jammed state. It has been a longstanding problem to determine
whether this class of systems can be described by concepts arising from
equilibrium statistical mechanics, such as an ``effective temperature'' and
``compactivity''. The measurement of the effective temperature is realized in
the laboratory by slowly shearing a closely-packed ensemble of spherical beads
confined by an external pressure in a Couette geometry. All the probe particles
considered in this study, independent of their characteristic features,
equilibrate at the same temperature, given by the packing density of the
system.Comment: 22 pages, 7 figures, more informations at http://www.jamlab.or
Aspetti dell'alimentazione di alcune specie di selaci del Canale di Sicilia
I Selaci occupano gli ultimi livelli delle reti trofiche marine: si tratta infatti di carnivori
che, spesso, predano risorse utili anche all'uomo. Numerose specie demersali (squali,
razze e torpedini) si alimentano, infatti, con organismi di interesse commerciale come
Aristeidi, Peneidi, Cefalopodi e Pesci ossei.
Le abitudini alimentari dei Selaci demersali del Canale di Sicilia sono quasi
completamente sc
onosciute; esistono in letteratura i lavori di Capapé relativi alle acque
tunisine, che si limitano ad una descrizione puramente qualitativa delle diete ma che
hanno tuttavia evidenziato preferenze verso Crostacei Decapodi, Cefalopodi e Teleostei.
Lo studio dei contenuti stomacali dei Selaci può fornire dunque elementi utili alla
comprensione delle reti trofiche demersali, all'indagine sull'esistenza di competizione tra
le diverse specie e allo studio dell'interferenza con prede di valore commerciale
Reentrant Peak Effect in an anisotropic superconductor 2H-NbSe_2 : Role of disorder
The reentrant nature of Peak Effect is established in a single crystal of
2H-NbSe_2 via electrical transport and dc magnetisation studies. The role of
disorder on the reentrant branch of PE has been examined in three single
crystals with varying levels of quenched random disorder. Increasing disorder
presumably shrinks the (H,T) parameter space over which vortex array retains
spatial order. Although, the upper branch of the PE curve is somewhat robust,
the lower reentrant branch of the same curve is strongly affected by disorder.Comment: 5 Pages of text, 4 figure
Plastic Flow, Voltage Bursts, and Vortex Avalanches in Superconductors
We use large-scale parallel simulations to compute the motion of
superconducting magnetic vortices during avalanches triggered by small field
increases. We find that experimentally observable voltage bursts correspond to
pulsing vortex movement along branched channels or winding chains, and relate
vortex flow images to features of statistical distributions. As pin density is
increased, a crossover occurs from interstitial motion in narrow easy-flow
winding channels with typical avalanche sizes, to pin-to-pin motion in broad
channels, characterized by a very broad distribution of sizes. Our results are
consistent with recent experiments.Comment: 4 pages, Latex, 4 figures included. Movies available at
http://www-personal.engin.umich.edu/~nor
Evaluation of frameworks of analysis employed in studies of exclusion zones
The purpose of this Work Package is to examine the various approaches to analysing fishery
exclusion zones (FEZs) and to identify the circumstances in which one approach might be
preferred to another. Our concern here is not so much with answering questions about exclusion
zones - these being dealt with in later Work Packages - as with articulating the questions
themselves and in understanding how in principle they could be addressed. An important theme
is the precision with which questions need to be answered, since this will determine the type of
information collected and how such information is analysed. The question ' is an exclusion zone
likely to improve the condition of this fishery ?' is less precise and less demanding of data than
the question ' by how much will an exclusion zone improve this fishery ?' since it could in
principle be answered by expert judgement rather than quantitative analysis. In practice fisheries
managers may be confronted with situations where decisions have to be made quickly, and
qualitative answers may be the only thing possible in circumstances where data cannot be
obtained in the available time.
The Work Package will look at FEZs from a number of different perspectives, but its dominant
concern is with the information – principally in the form of socio-economic and biological
indicators - needed by fisheries managers in order to evaluate the effectiveness of FEZs. To
contextualise the discussion we start by outlining a paradigm for understanding the linkages
between human activities and the environment, showing how it can be applied to fisheries and
marine resources. The Work Package then considers the substantive information requirements
of fisheries managers, commencing with socio-economic assessment and moving on to a review
of biological assessment and the progress which has been made in the development of
mathematical models of FEZs. Bio-economic modelling, which is essentially a specialised type of
socio-economic assessment in which explicit account is taken of the interaction between the
biological and economic components of the fishing system, is dealt with in the final section
Hybrid supramolecular gels of Fmoc-F/halloysite nanotubes: systems for sustained release of camptothecin
Supramolecular gel hybrids obtained by self-assembly of Fmoc-L-phenylalanine (Fmoc-F) in the presence of functionalized halloysite nanotubes (f-HNT) were obtained in biocompatible solvents and employed as carriers for the delivery of camptothecin (CPT) molecules. The synthesis of the new f-HNT material as well as its characterization are described. The properties of the hybrid hydrogels and organogels were analyzed by several techniques. The presence of small amounts of f-HNT allows good dispersion of the tubes and the subsequent formation of homogeneous gels. The experimental results show that f-HNT functions only as an additive in the hybrid gels and does not demonstrate gelator behavior. The in vitro kinetic release from both f-HNT/CPT and Fmoc-F/f-HNT/CPT was studied in media that imitates physiological conditions, and the factors controlling the release process were determined and discussed. Furthermore, the antiproliferative in vitro activities of the gels were evaluated towards human cervical cancer HeLa cells. A comparison of data collected in both systems shows the synergistic action of f-HNT and the gel matrix in controlling the release of CPT in the media and maintaining the drug in its active form. Finally, a comparison with pristine HNT is also reported. This study suggests a suitable strategy to obtain two-component gel hybrids based on nanocarriers with controlled drug carrier capacity for biomedical applications
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