195 research outputs found
Lattice specific heat for the RMIn (R = Gd, La, Y, M = Co, Rh) compounds: non-magnetic contribution subtraction
We analyze theoretically a common experimental process used to obtain the
magnetic contribution to the specific heat of a given magnetic material. In the
procedure, the specific heat of a non-magnetic analog is measured and used to
subtract the non-magnetic contributions, which are generally dominated by the
lattice degrees of freedom in a wide range of temperatures. We calculate the
lattice contribution to the specific heat for the magnetic compounds GdMIn
(M = Co, Rh) and for the non-magnetic YMIn and LaMIn (M = Co, Rh),
using density functional theory based methods. We find that the best
non-magnetic analog for the subtraction depends on the magnetic material and on
the range of temperatures. While the phonon specific heat contribution of
YRhIn is an excellent approximation to the one of GdCoIn in the full
temperature range, for GdRhIn we find a better agreement with LaCoIn,
in both cases, as a result of an optimum compensation effect between masses and
volumes. We present measurements of the specific heat of the compounds
GdMIn (M = Co, Rh) up to room temperature where it surpasses the value
expected from the Dulong-Petit law. We obtain a good agreement between theory
and experiment when we include anharmonic effects in the calculations
Phenotypic and molecular characterization of plants regenerated from non-cryopreserved and cryopreserved wild Solanum lycopersicum Mill. seeds
BACKGROUND: Before cryopreservation is routinely used, its effect on the trueness-to-type of the regenerated plant material needs to be evaluated. OBJECTIVE: In this work, we studied the effect of seed cryopreservation on the phenotypic and molecular characteristics of wild Solanum lycopersicum Mill. plants. METHODS: Thirty-five morphological traits of plants regenerated from cryopreserved seeds were compared to those measured on plants regenerated from non-cryopreserved seeds. RESULT: No statistically significant differences were observed between cryopreserved and non-cryopreserved samples, either in the first or in the second generation post-liquid nitrogen exposure. However, at the molecular level, the genetic analyses performed on the second generation plants germinated from control and cryopreserved seeds using 14 nuclear Simple Sequences Repeats (SSR) markers uncovered some changes in microsatellite length between control and cryopreserved samples. These results confirm at the botanical phenotype level the effectiveness of seed cryostorage for conservation and regeneration of true-to-type S. lycopersicum plants. CONCLUSION: Further experiments are required to clarify potential phenotypic effects of the changes observed in the DNA
Phenotypic and molecular characterization of Phaseolus vulgaris plants from non-cryopreserved and cryopreserved seeds
The objective of this work was to evaluate if cryostorage of Phaseolus vulgaris L. seeds induced variations in regenerated plants at the phenotypic and molecular levels. A series of agricultural traits was measured on plants grown from control, non-cryopreserved and cryopreserved seeds, and the genetic stability of plants of the second generation was analysed at selected microsatellite loci. The phenotype of the second generation plants was evaluated as well. No statistically significant phenotypic differences were observed for the parameters measured, neither in the first nor in the second generations. Averaging both treatments, about 76% of the seeds had germinated 10 days after sowing. At harvest we recorded plants with about 73 cm in height, 13 stem internodes, 25 fruits, 103 grains and 4 grains per fruit. One hundred seeds weighted about 26 g. The genetic analyses performed on the second generation plants using six nuclear Simple Sequences Repeats (SSR) markers revealed no changes in microsatellite length between control and cryopreserved samples, implying that there was no effect of seed liquid nitrogen exposure on genome integrity. The phenotypic and molecular results reported here confirm that cryostorage is an efficient and reliable technique to conserve P. vulgaris seeds and regenerate true-to-type plants
Improved fractional Poincaré type inequalities in John domains
We obtain improved fractional Poincaré inequalities in John domains of a metric space endowed with a doubling measure under some mild regularity conditions on the measure . We also give sufficient conditions on a bounded domain to support fractional Poincaré type inequalities in this setting.Universidad Nacional de La Plata, under grant 11/X805
Universidad de Buenos Aires, under grant 20020120100050BA
Agencia Nacional de Promoción Científica y Tecnológica, under grant PICT 2014-177
Preliminary report on cross-species microsatellite amplification for bumblebee biodiversity and conservation studies
The Iberian Peninsula holds a high diversity of bumblebees but there is a general lack of information about their biodiversity in this area. To overcome this and facilitate conservation studies, we present two novel multiplex assays for the amplification of six and five microsatellite loci respectively. Both assays successfully amplified for most of the studied species in the Iberian populations. Sibling workers and population genetic parameters were analysed in the managed species B. terrestris and in the wild species B. monticola and B. mesomelas, demonstrating the capability of these multiplex assays for biodiversity studies of both managed and wild bumblebee species
Quince (Cydonia oblonga) in vitro plant root formation through an automated temporary inmersion system, and its acclimation
Artículo científicoQuince (Cydonia oblonga) is a non-traditional fruit tree found in Costa Rica that has
therapeutic and nutritional properties; however its slow growth and root formation prevents the production
of a homogeneous population when using conventional farming techniques. Hence, the aim of this research
project was to generate uniform plant material in a reduced time span using a temporary immersion bioreactor
system (RITAS ®). A semisolid rooting MS culture medium supplemented with 0.1 mg L-1 NAA; 0.3 mg L-1
IBA and 3% sucrose (pH 6.5), developed in the Centro de Investigación en Biotecnología (CIB), Instituto
Tecnológico de Costa Rica (ITCR), in Cartago, was used as a reference medium. Four different variations
in the sucrose concentration (1%, 2%, 3%, and 4%) were performed in liquid medium. Each trial was
evaluated with in vitro plants which had been previously exposed to the culture medium of the corresponding
treatments, in a stationary mode and for a 15 day long period, and with in vitro plants without any previous
treatment (a total of eight treatments). The comparison of the root formation percentages evidenced the clear
effect of sucrose concentration used, with the best results obtained when using the 2% sucrose trial with no
pre-treatment (73.3%). The in vitro plants were acclimated in cylinders made out of peat, have previously
been disinfected with fungicide, and placed in a humidity chamber at a 20.5°C average temperature and a
75,5% relative humidity for the establishment of weekly fertilizing cycles. The acclimation process generated
an 80% survival rate, since several seedlings experienced stem strangulation caused by a fungal attack.
The conidiophores identified through optical and scanning electron microscopy evidenced the presence of
Cladosporium spp., which was controlled with carbendazim and iprodione fungicides
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