2,725 research outputs found
Testing a Model of Flow and Heat Transfer for U-shaped Geothermal Exchangers
Among renewable resources, geothermal energy is one of the most promising for its independence on
weather conditions. However, design and installation of borehole heat exchangers on low enthalpy regions
must consider numerous influencing factors. Here, we focus on the efficiency improvement in hot water
production and heating and cooling of buildings of a pilot geothermal plant, which was implemented as part
of a hybrid system within the frame of a research project at the University of Camerino (Italy). The aims of
the geothermal plant were to study the subsoil thermal properties and monitoring the parameters of the system
during operation. As an important application for the design and sizing of low enthalpy geothermal systems,
we propose a mathematical model to study the heat transfer between the fluid circulating in the pipes and the
underground, where the mutual influence between the soil and the exchanger is considered. We present results
of these approximated solutions based on experimental measurements acquired in the actual geothermal
exchangers. Laboratory and in situ tests were also carried out to investigate the underground thermal
properties and thermal regime of the heterogeneous soil sedimentary succession
Development and optimization of a method for analyzing biodiesel mixtures with non-aqueous reversed phase liquid chromatography
Biodiesel (a mixture of fatty acid esters) is normally analyzed using gas chromatography/flame ionization
detection, as specified by the ASTM D6584 and EN14105 standards. This paper proposes a binary gradient
method for analyzing biodiesel mixtures using non-aqueous reverse phase HPLC with a UV detector
capable of overcoming the drawbacks of the gas chromatographic technique normally used. The new analytical
method was developed by means of a statistical sensitivity analysis applied to the main parameters
influencing the recording, using the full factorial design method combined with the Yates algorithm and
the steepest ascent optimization procedure. The present study shows the influence of the main biodiesel
mixture separation analysis parameters. The resulting tool proved valid for analyzing not only biodiesel
but also any traces of unreacted oil
A modular approach for automated sample preparation and chemical analysis
Changes in international relations, especially within the past several years, have dramatically affected the programmatic thrusts of the U.S. Department of Energy (DOE). The DOE now is addressing the environmental cleanup required as a result of 50 years of nuclear arms research and production. One major obstacle in the remediation of these areas is the chemical determination of potentially contaminated material using currently acceptable practices. Process bottlenecks and exposure to hazardous conditions pose problems for the DOE. One proposed solution is the application of modular automated chemistry using Standard Laboratory Modules (SLM) to perform Standard Analysis Methods (SAM). The Contaminant Analysis Automation (CAA) Program has developed standards and prototype equipment that will accelerate the development of modular chemistry technology and is transferring this technology to private industry
Impact of mild oven cooking treatments on carotenoids and tocopherols of cheddar and depurple cauliflower (Brassica oleracea L. var. Botrytis)
The effect of steam and sous-vide oven procedures on liposoluble antioxidants of colored cauliflower (orange and purple) was assessed for the first time and compared with domestic practice (boiling). In raw samples, the total carotenoid content was 10-fold higher in Cheddar than in Depurple (20.9 \ub1 2.1 vs. 2.3 \ub1 0.5 mg/kg dry weight), whereas the level of tocopherols was similar (28.5 \ub1 4.4 vs. 33 \ub1 5.2 mg/kg dry weight). The Cheddar liposoluble antioxidant matter contained violaxanthin, neoxanthin, \u3b1-carotene and \u3b4-tocopherol, not detected in Depurple. All tests increased the bioactive compounds extractability with steam oven and sous-vide displaying similar effects, lower than boiling. In boiled Cheddar cauliflower, the total carotenoids and tocopherols contents increased with cooking time until they were 13-fold and 6-fold more than in raw cauliflower, respectively. Conversely, in the Depurple variety, contents increased by half with respect to the orange variety. However, from a nutritional point of view, no differences were revealed among the three different cooking treatments in terms of vitamin A and E levels expressed in \u3bcg/100 g of fresh vegetable because of the higher water content of boiled samples that must be considered when evaluating the effect of thermal treatment on cauliflower nutritional traits
A model to explain angular distributions of and decays into and
BESIII data show a particular angular distribution for the decay of the
and mesons into the hyperons
and . More in details the angular distribution of
the decay exhibits an opposite trend
with respect to that of the other three channels: , and
. We define a model to explain the
origin of this phenomenon.Comment: 6 pages, 7 figures, to be published in Chinese Physics
Dietary oregano (Origanum vulgare L.) aqueous extract improves oxidative stability and consumer acceptance of meat enriched with CLA and n-3 PUFA in broilers.
Abstract The effect of a dietary oregano aqueous extract on meat fatty acid profile, quality, and consumer acceptance in chickens fed a diet rich in polyunsaturated fatty acids (PUFA) was evaluated in 3 consecutive trials. For each trial, 171 day-old Ross 308 chicks were randomly divided in replicates of 19 birds each and assigned to one of 3 experimental diets: 1) basal control diet, 2) basal diet supplemented with 0.2 g/kg of oregano aqueous extract, and 3) basal diet supplemented with 150 ppm of vitamin E (as positive control). To better analyze the antioxidant activity of both oregano and vitamin E, all the experimental diets were enriched with a fatty acid supplement consisting in a mixture of PUFA at the same dose (1.16 %) in both starter and finisher feeds. Oregano supplementation positively influenced (P Results obtained in the present study allow stating that using oregano aqueous extract in diets enriched with PUFA can represent a valid solution to increase live weight of chickens, improve resistance to oxidation of meat, and positively influence consumer perception of poultry meat
A description of the ratio between electric and magnetic proton form factors by using space-like, time-like data and dispersion relations
We use the available information on the ratio between the electric and
magnetic proton form factors coming from recently published space-like data and
from the few available time-like data. We apply a dispersive procedure on these
data to evaluate the behaviour of this ratio, as a complex function, for all
values of q^2.Comment: 12 pages, 7 Encapsulated Postscript figures, uses epsfig, rotating,
exscale, amsmath, cite, latexsym, graphics, color packages, added reference
Corrections to the generalized vector dominance due to diffractive rho_3 production
The idea of the vector dominance is still in use in various analyses of
experimental data of photon-hadron reactions. It makes sense, therefore, to
recast results of microscopic calculations of such reactions in this language.
Here we present the diffractive DIS production as a specific
correction to the generalized vector dominance. We perform a coupled channel
analysis of spin-orbital excitations in diffractive photoproduction and
reiterate the point that rho_3 in diffractive DIS will be sensitive to a novel
aspect of diffraction.Comment: 12 pages, 2 figure
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