1,323 research outputs found
Applications of low enthalpy geothermal energy: the case of the Faculty of Physical and Mathematical Sciences at the University of Chile
In recent decades, the industry has observed a significant shift towards the use of renewable energy, such as solar, wind and geothermal. The Chilean scenario has not been an exception, and much progress has been made in sustainable energy prospection and implementation, especially in the electricity sector, where solar and wind power amount 2300 MW, and since April 2017, the first geothermal power plant (48 MW) has come into operation. In the area of low enthalpy geothermal energy, the use is around 19 MW. The Faculty of Physical and Mathematical Sciences at the University of Chile has been contributing to this transformational process, with its Sustainable Campus initiative. The first step of this initiative is the introduction of renewable energy on site, which has been achieved through the installation of a solar photovoltaic plant of 15 kW. Along this line, the design and implementation of a geothermal air conditioning system (HAVC) is underway, which will serve the classrooms and offices in the traditional engineering building of the campus. The technology to be used in this project is the Ground Heat Pump (GHP). The present paper includes an introduction of the applications of low enthalpy geothermal energy in Chile, a description of the Office of Engineering for Sustainable Development at the Faculty of Physical and Mathematical Sciences, and the design of a geothermal HAVC system in the university campus, considering economic, environmental, technical and social aspects. Besides the operation of the GHP, the system will be used for teaching purposes to incorporate sustainable development in the curriculum of the university. The expected savings of the geothermal system versus an aerothermal design are 41,070 kWh annually, considering both cooling and heating.This research was partially funded by the Andean Geothermal Center of Excellence (CEGA) and the Complex Engineering Systems Institute, ISCI (Project CONICYT: FB0816)
Determinants of Non-Mining Exports: A Regional Perspective
The Chilean non-mining export sector has experienced a substantial increase over the last years, although exports to the main regions have evolved with different patterns. This work analyzes the role of the real exchange rate and world economic activity during the 1990-2001 period, after performing an extensive refinement and cleaning of export bundles by region. Based on a multivariate cointegration analysis, we find different effects of the real exchange rate and world output on the exported quantum. The long-run elasticity of the real exchange rate goes from 0.2 to 0.8 percent for Europe, Asia and United States, and it is non significant for Aladi countries, for which a lower effect of this latter variable is found as a determinant of regional exports. On the other hand, elasticity with respect to world output ranges between 2.3 and 4 percent for the United States, and between 1.2 and 2 percent for the other regions. A panel analysis supports the view that world output plays a significant role,while the real exchange rate is less important. Finally, our preliminary evidence suggests that foreign country tariff reductions may increase regional exports.
Emulsifying Properties of Hydrolized Sunflower Lecithins by Phospholipases A2 of Different Sources
The chemistry of H2NC in the interstellar medium and the role of the C + NH3 reaction
We carried out an observational search for the recently discovered molecule
H2NC, and its more stable isomer H2CN, toward eight cold dense clouds (L1544,
L134N, TMC-2, Lupus-1A, L1489, TMC-1 NH3, L1498, and L1641N) and two diffuse
clouds (B0415+379 and B0355+508) in an attempt to constrain its abundance in
different types of interstellar regions and shed light on its formation
mechanism. We detected H2NC in most of the cold dense clouds targeted, 7 out of
8, while H2CN was only detected in 5 out of 8 clouds. The column densities
derived for both H2NC and H2CN are in the range 1e11-1e12 cm-2 and the
abundance ratio H2NC/H2CN varies between 0.51 and >2.7. The metastable isomer
H2NC is therefore widespread in cold dense clouds where it is present with an
abundance similar to that of H2CN. We did not detect either H2NC or H2CN in any
of the two diffuse clouds targeted, which does not allow to shed light on how
the chemistry of H2NC and H2CN varies between dense and diffuse clouds. We
found that the column density of H2NC is correlated with that of NH3, which
strongly suggests that these two molecules are chemically linked, most likely
ammonia being a precursor of H2NC through the C + NH3 reaction. We performed
electronic structure and statistical calculations which show that both H2CN and
H2NC can be formed in the C + NH3 reaction through two different channels
involving two different transition states which lie very close in energy. The
predicted product branching ratio H2NC/H2CN is very method dependent but values
between 0.5 and 0.8 are the most likely ones. Therefore, both the astronomical
observations and the theoretical calculations support that the reaction C + NH3
is the main source of H2NC in interstellar clouds.Comment: Accepted for publication in A&
Antioxidant and Emulsifying Properties of Modified Sunflower Lecithin by Fractionation with Ethanol-Water Mixtures
Lecithins are a mixture of acetone insoluble phospholipids, containing mainly phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidic acid (PA), and other minor substances such as carbohydrates and triglycerides [1-3]. The production of sunflower oil in Argentina, is of utmost importance from an economic point of view [4]. In this country, sunflower lecithin could represent an alternative to soybean lecithin because it is considered a non-GMO product, which is in accordance with the preference of some consumersFil: Cabezas, Dario Marcelino. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Guiotto, Estefania Nancy. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Diehl, Bernd W. K.. No especifíca;Fil: Tomás, Mabel Cristina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentin
Discovery of HC4NC in TMC-1: A study of the isomers of HC3N, HC5N, and HC7N
We present a study of the isocyano isomers of the cyanopolyynes HC3N, HC5N,
and HC7N in TMC-1 and IRC+10216 carried out with the Yebes 40m radio telescope.
This study has enabled us to report the detection, for the first time in space,
of HCCCCNC in TMC-1 and to give upper limits for HC6NC in the same source. In
addition, the deuterated isotopologues of HCCNC and HNCCC were detected, along
with all 13C substitutions of HCCNC, also for the first time in space. The
abundance ratios of HC3N and HC5N, with their isomers, are very different in
TMC-1 and IRC+10216, namely, N(HC5N)/N(HC4NC) is 300 and >2100, respectively.
We discuss the chemistry of the metastable isomers of cyanopolyynes in terms of
the most likely formation pathways and by comparing observational abundance
ratios between different sources.Comment: This article was submitted to A&A on 27/08/2020 and accepted for
publication on 11/09/202
Burrknots as food source for larval development of Grapholita molesta (Lepidoptera: Tortricidae) on apple trees.
Grapholita molesta (Busck) is one of the main pests of apple trees, and lives on their shoots and fruits. In southern Brazil, the insect is also found on old branches and structures similar to aerial roots, so-called burrknots. This study evaluated the development and population growth potential of G. molesta fed on burrknots, compared with apple fruit cultivar. Fuji and a corn-based artiÞcial diet. The study was carried out in the laboratory under controlled temperature (25 1C), relative humidity (7010%), and photophase (16 h). The biological parameters of the immature and adult stages were determined, and a fertility life table was constructed. Insects fed on burrknots showed a longer duration and a lower survival for the egg-to-adult period (29.3 d and 22.5%) compared with those that fed on apples (25.1 d and 30.0%) and artiÞcial diet (23.9 d and 54.8%). Insects reared on aerial roots had a lower pupal weight (10.0 mg) compared with those reared on either artiÞcial diet (13.7 mg) or apple cultivar. Fuji (12.4 mg). The fecundity and longevity of males and females did not signiÞcantly differ for the three foods. Based on the fertility life table, insects reared on burrknots had the lowest net reproductive rate (Ro), intrinsic rate of population growth (rm) and finite rate of increase, compared with insects reared on artiÞcial diet and apple fruit. Burrknots support the development of the complete cycle of G. molesta, which allows populations of this pest to increase in orchards
Discovery of HC3O+ in space: The chemistry of O-bearing species in TMC-1
Using the Yebes 40m and IRAM 30m radio telescopes, we detected a series of
harmonically related lines with a rotational constant B0=4460.590 +/- 0.001 MHz
and a distortion constant D0=0.511 +/- 0.005 kHz towards the cold dense core
TMC-1. High-level-of-theory ab initio calculations indicate that the best
possible candidate is protonated tricarbon monoxide, HC3O+. We have succeeded
in producing this species in the laboratory and observed its J = 2-1 and 3-2
rotational transitions. Hence, we report the discovery of HC3O+ in space based
on our observations, theoretical calculations, and laboratory experiments. We
derive an abundance ratio N(C3O)/N(HC3O+) = 7. The high abundance of the
protonated form of C3O is due to the high proton affinity of the neutral
species. The chemistry of O-bearing species is modelled, and predictions are
compared to the derived abundances from our data for the most prominent
O-bearing species in TMC-1.Comment: Accepted for publication in A&A Letter
A new protonated molecule discovered in TMC-1: HCCNCH+
In recent years we have seen an important increase in the number of
protonated molecules detected in cold dense clouds. Here we report the
detection in TMC-1 of HCCNCH+, the protonated form of HCCNC, which is a
metastable isomer of HC3N. This is the first protonated form of a metastable
isomer detected in a cold dense cloud. The detection was based on observations
carried out with the Yebes 40m and IRAM 30m telescopes, which revealed four
harmonically related lines. We derive a rotational constant B = 4664.431891 +/-
0.000692 MHz and a centrifugal distortion constant D = 519.14 +/- 4.14 Hz. From
a high-level ab initio screening of potential carriers we confidently assign
the series of lines to the ion HCCNCH+. We derive a column density of (3.0 +/-
0.5)e10 cm-2 for HCCNCH+, which results in a HCCNCH+/HCCNC abundance ratio of
0.010 +/- 0.002. This value is well reproduced by a state-of-the-art chemical
model, which however is subject to important uncertainties regarding the
chemistry of HCCNCH+. The observational and theoretical status of protonated
molecules in cold dense clouds indicate that there exists a global trend in
which protonated-to-neutral abundance ratios MH+/M increase with increasing
proton affinity of the neutral M, although if one restricts to species M with
high proton affinities (>700 kJ/mol), MH+/M ratios fall in the range 0.001-0.1,
with no apparent correlation with proton affinity. We suggest various
protonated molecules that are good candidates for detection in cold dense
clouds in the near future.Comment: Accepted for publication in A&A Letter
Interstellar nitrile anions: Detection of C3N- and C5N- in TMC-1
We report on the first detection of C3N- and C5N- towards the cold dark core
TMC-1 in the Taurus region, using the Yebes 40 m telescope. The observed
C3N/C3N- and C5N/C5N- abundance ratios are 140 and 2, respectively; that is
similar to those found in the circumstellar envelope of the carbon-rich star
IRC+10216. Although the formation mechanisms for the neutrals are different in
interstellar (ion-neutral reactions) and circumstellar clouds
(photodissociation and radical-neutral reactions), the similarity of the
C3N/C3N- and C5N/C5N- abundance ratios strongly suggests a common chemical path
for the formation of these anions in interstellar and circumstellar clouds. We
discuss the role of radiative electronic attachment, reactions between N atoms
and carbon chain anions Cn-, and that of H- reactions with HC3N and HC5N as
possible routes to form CnN-. The detection of C5N- in TMC-1 gives strong
support for assigning to this anion the lines found in IRC+10216, as it
excludes the possibility of a metal-bearing species, or a vibrationally excited
state. New sets of rotational parameters have been derived from the observed
frequencies in TMC-1 and IRC+10216 for C5N- and the neutral radical C5N.Comment: Accepted for publication in A&A Letter
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