249 research outputs found
Interaction of 8 He with 208Pb at near-barrier energies: 4 He and 6 He production
Spanish Ministry of Economy and Competitiveness-FPA-2010-22131-CO2-01 (FINURA) y FPA2013-47327-C2-1-RMinistry of Science and Higher Education of Poland-N202 033637National Science Centre of Poland-2013/08/M/ST2/00257 (LEA-COPIGAL) y 2014/14/M/ST2/00738 (COPIN-INFN Collaboration)European Science Foundation-EUI2009-04163432 (EUROGENESIS
Depletion of the heaviest stable N isotope is associated with NH4+/NH3 toxicity in NH4+-fed plants
Open Access article - can be viewed online without a subscription at: http://dx.doi.org/doi:10.1186/1471-2229-11-83Background: In plants, nitrate (NO3
-) nutrition gives rise to a natural N isotopic signature (δ15N), which correlates
with the δ15N of the N source. However, little is known about the relationship between the δ15N of the N source
and the 14N/15N fractionation in plants under ammonium (NH4
+) nutrition. When NH4
+ is the major N source, the
two forms, NH4
+ and NH3, are present in the nutrient solution. There is a 1.025 thermodynamic isotope effect
between NH3 (g) and NH4
+ (aq) which drives to a different δ15N. Nine plant species with different NH4
+-sensitivities
were cultured hydroponically with NO3
- or NH4
+ as the sole N sources, and plant growth and δ15N were
determined. Short-term NH4
+/NH3 uptake experiments at pH 6.0 and 9.0 (which favours NH3 form) were carried out
in order to support and substantiate our hypothesis. N source fractionation throughout the whole plant was
interpreted on the basis of the relative transport of NH4
+ and NH3.
Results: Several NO3
--fed plants were consistently enriched in 15N, whereas plants under NH4
+ nutrition were
depleted of 15N. It was shown that more sensitive plants to NH4
+ toxicity were the most depleted in 15N. In
parallel, N-deficient pea and spinach plants fed with 15NH4
+ showed an increased level of NH3 uptake at alkaline
pH that was related to the 15N depletion of the plant. Tolerant to NH4
+ pea plants or sensitive spinach plants
showed similar trend on 15N depletion while slight differences in the time kinetics were observed during the initial
stages. The use of RbNO3 as control discarded that the differences observed arise from pH detrimental effects.
Conclusions: This article proposes that the negative values of δ15N in NH4
+-fed plants are originated from NH3
uptake by plants. Moreover, this depletion of the heavier N isotope is proportional to the NH4
+/NH3 toxicity in
plants species. Therefore, we hypothesise that the low affinity transport system for NH4
+ may have two
components: one that transports N in the molecular form and is associated with fractionation and another that
transports N in the ionic form and is not associated with fractionatio
Is the optical model valid for the scattering of exotic nuclei?
The optical model, and its applications to elastic, inelastic and transfer reactions is reviewed. The applicability of the optical model to the collisions of exotic nuclei is discussed. The sensitivity of recent experimental data of elastic scattering of 6He on 208Pb to the characteristics of the optical potential is investigated.Comisión Interministerial de Ciencia y Tecnología (CICYT). España FPA2002-04181-C04-02, FPA2002-04181-C04-04, FPA2003-0595
Signature of microRNA expression during osteogenic differentiation of bone marrow MSCs reveals a putative role of miR-335-5p in osteoarthritis
Background: The aim of this study was to evaluate, the existence of a
signature of differentially expressed microRNAs (miRNAs) during
osteogenic differentiation of bone marrow MSCs from OA and healthy
donors and to describe their possible implication in joint regeneration
through modulation of molecular mechanisms involved in homeostatic
control in OA pathophysiology.
Methods: Following phenotypic assessment of BM-MSCs obtained from OA
diagnosed patients (n = 10) and non-OA (n = 10), total small RNA was
isolated after osteogenic induction for 1, 10 and 21 days, miRNA
profiles were generated using a commercial expression array of 754
well-characterized miRNAs. MiRNAs, with consistent differential
expression were selected for further validation by quantitative
reverse-transcription polymerase chain reaction (qRT-PCR) analysis.
Results: A total of 246 miRNAs were differentially expressed (fold
change >=+/- 2, P <= 0.05) between OA and non-OA BM-MSC samples; these
miRNAs showed variable interactions depending on the cell and
differentiation status. Two miRNAs, hsa-miR-210 and hsa-miR-335-5p out
of 21 used for validation showed a significant downregulated expression
during induced osteogenesis. In particular hsa-miR-335-5p, a critical
regulator in bone homeostasis, was further studied. hsa-miR-335-5p
downregulation in OA-MSCs, as well as their host coding gene, MEST, were
also assessed.
Conclusions: To our knowledge, this study represents the most
comprehensive assessment to date of miRNA expression profiling in
BM-MSCs from OA patients and their role during osteogenic
differentiation. We describe the existence of a correlation between
miR-335-5p expression and OA indicating the putative role of this miRNA
in OA features. These findings, may contribute to our understanding of
the molecular mechanisms involved in MSCs mediated homeostatic control
in OA pathophysiology that could be applicable in future therapeutic
approaches.This work was supported in part by institutional grants from the
Instituto de Salud Carlos III CP10/00346 and PI10/00178 and the Spanish
society of orthopaedics surgery and traumatology (SECOT).; J.R. Lamas is
supported by the Miguel Servet program from ISCIII-Fondo Investigacion
Sanitaria-Spain (CP10/00346).S
Kinematic reduction of reaction-diffusion fronts with multiplicative noise: Derivation of stochastic sharp-interface equations
We study the dynamics of generic reaction-diffusion fronts, including pulses
and chemical waves, in the presence of multiplicative noise. We discuss the
connection between the reaction-diffusion Langevin-like field equations and the
kinematic (eikonal) description in terms of a stochastic moving-boundary or
sharp-interface approximation. We find that the effective noise is additive and
we relate its strength to the noise parameters in the original field equations,
to first order in noise strength, but including a partial resummation to all
orders which captures the singular dependence on the microscopic cutoff
associated to the spatial correlation of the noise. This dependence is
essential for a quantitative and qualitative understanding of fluctuating
fronts, affecting both scaling properties and nonuniversal quantities. Our
results predict phenomena such as the shift of the transition point between the
pushed and pulled regimes of front propagation, in terms of the noise
parameters, and the corresponding transition to a non-KPZ universality class.
We assess the quantitative validity of the results in several examples
including equilibrium fluctuations, kinetic roughening, and the noise-induced
pushed-pulled transition, which is predicted and observed for the first time.
The analytical predictions are successfully tested against rigorous results and
show excellent agreement with numerical simulations of reaction-diffusion field
equations with multiplicative noise.Comment: 17 pages, 6 figure
Study of the break-up channel in 11Li+208Pb collisions at energies around the Coulomb barrier
We present a study of 11Li+208 Pb collisions at energies around the Coulomb barrier (Elab = 24.3 and 29.8 MeV), measured at the post-accelerated beam facility, ISAC II, at TRIUMF (Vancouver, Canada). A remarkably large yield of 9Li has been observed, a result that is attributed to the weak binding of the 11Li nucleus. The angular distribution of this 9Li yield, relative to the elastic one, has been analysed in terms of first-order semiclassical calculations as well as four-body and three-body Continuum-Discretized Coupled-Channels (CDCC) calculations, based on a three-body and di-neutron model of the 11Li nucleus, respectively. The calculations reproduce well the trend of the data and support the existence of a large concentration of B (E1) strength at very low excitation energies. The connection of this large B (E1) with a possible low-lying dipole resonance is discussed
Study of the near-barrier scattering of 8He on 208Pb
The structure and dynamics of 8He have been studied through the collision process with a 208Pb target at energies of 22 and 16 MeV, above and below the Coulomb barrier, respectively. The energy and angular distributions of the elastically scattered 8He and the 6,4He fragments were measured. In this paper, we discuss the method used to determine the effective position of the beam spot on the reaction target and the scattering and solid angles of each pixel of the detector array.Ministerio de Economía y Competitividad FPA2010-22131-C021-01, FPA2014-59954-C3-1-PMinistry of Science and Higher Education of Poland N202 033637European Science Foundation EUI2009-0416
Biochar reduces the efficiency of nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) mitigating N2O emissions
Among strategies suggested to decrease agricultural soil N2O losses, the use of nitrification inhibitors such as DMPP (3,4-dimethylpyrazole phosphate) has been proposed. However, the efficiency of DMPP might be affected by soil amendments, such as biochar, which has been shown to reduce N2O emissions. This study evaluated the synergic effect of a woody biochar applied with DMPP on soil N2O emissions. A incubation study was conducted with a silt loam soil and a biochar obtained from Pinus taeda at 500 degrees C. Two biochar rates (0 and 2% (w/w)) and three different nitrogen treatments (unfertilized, fertilized and fertilized + DMPP) were assayed under two contrasting soil water content levels (40% and 80% of water filled pore space (WFPS)) over a 163 day incubation period. Results showed that DMPP reduced N2O emissions by reducing ammonia-oxidizing bacteria (AOB) populations and promoting the last step of denitrification (measured by the ratio nosZI + nosZII/nirS + nirK genes). Biochar mitigated N2O emissions only at 40% WFPS due to a reduction in AOB population. However, when DMPP was applied to the biochar amended soil, a counteracting effect was observed, since the N2O mitigation induced by DMPP was lower than in control soil, demonstrating that this biochar diminishes the efficiency of the DMPP both at low and high soil water contents.This work was funded by the Spanish Government (AGL2015-64582-C3-2-R MINECO/FEDER), by the Basque Government (IT-932-16) and by the European Union (FACCE-CSA no 276610/MIT04-DESIGN-UPVASC, FACCE-CSA no 2814ERA01A and 2814ERA02A). This work is also supported by the USDA/NIFA Interagency Climate Change Grant Proposal number 2014-02114 [Project number 6657-12130-002-08I, Accession number 1003011] under the Multi-Partner Call on Agricultural Greenhouse Gas Research of the FACCE-Joint Program Initiative. Any opinions, findings, or recommendation expressed in this publication are those of the authors and do not necessarily reflect the view of the USDA. MLC was supported by a Ramon y Cajal contract from the Spanish Ministry of Economy and Competitiveness and thanks Fundacion Seneca for financing the project 19281/PI/14
Depletion of the heaviest stable N isotope is associated with NH4+/NH3 toxicity in NH4+-fed plants
Background: In plants, nitrate (NO3-) nutrition gives rise to a natural N isotopic signature (δ15N), which correlates
with the δ15N of the N source. However, little is known about the relationship between the δ15N of the N source
and the 14N/15N fractionation in plants under ammonium (NH4+) nutrition. When NH4
+ is the major N source, the two forms, NH4
+ and NH3, are present in the nutrient solution. There is a 1.025 thermodynamic isotope effect
between NH3 (g) and NH4
+ (aq) which drives to a different δ15N. Nine plant species with different NH4
+-sensitivities
were cultured hydroponically with NO3
- or NH4
+ as the sole N sources, and plant growth and δ15N were
determined. Short-term NH4
+/NH3 uptake experiments at pH 6.0 and 9.0 (which favours NH3 form) were carried out
in order to support and substantiate our hypothesis. N source fractionation throughout the whole plant was
interpreted on the basis of the relative transport of NH4
+ and NH3.
Results: Several NO3
--fed plants were consistently enriched in 15N, whereas plants under NH4
+ nutrition were
depleted of 15N. It was shown that more sensitive plants to NH4
+ toxicity were the most depleted in 15N. In
parallel, N-deficient pea and spinach plants fed with 15NH4
+ showed an increased level of NH3 uptake at alkaline
pH that was related to the 15N depletion of the plant. Tolerant to NH4
+ pea plants or sensitive spinach plants
showed similar trend on 15N depletion while slight differences in the time kinetics were observed during the initial
stages. The use of RbNO3 as control discarded that the differences observed arise from pH detrimental effects.
Conclusions: This article proposes that the negative values of δ15N in NH4
+-fed plants are originated from NH3
uptake by plants. Moreover, this depletion of the heavier N isotope is proportional to the NH4
+/NH3 toxicity in
plants species. Therefore, we hypothesise that the low affinity transport system for NH4
+ may have two
components: one that transports N in the molecular form and is associated with fractionation and another that
transports N in the ionic form and is not associated with fractionation.This work was supported by the Spanish MICIIN (grant nos. AGL2006-12792-CO2-
01 and 02 and AGL2009- 13339-CO2-01 and 02 [to P.A.-T. and C.G.M.] and
AGL2007-64432/AGR [to J.F.M.]), by the Portuguese FCT (PTDC/BIA- BEC/
099323/2008) and by the Basque Government IT526-10
11Li structural information from inclusive break-up measurements
IWM-EC 2014 – International Workshop on Multi facets of EoS and ClusteringStructure information of 11Li halo nucleus has been obtained from the inclusive break-up measurements of the 11Li+208Pb reactions at energies around the Coulomb barrier (Elab = 24.3 and 29.8 MeV). The effective break-up energy and the slope of B(E1) distribution close to the threshold have been extracted from the experimental dat
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