Effects of Salt Stress on Three Ecologically Distinct Plantago Species

Comparative studies on the responses to salt stress of taxonomically related taxa should help to elucidate relevant mechanisms of stress tolerance in plants. We have applied this strategy to three Plantago species adapted to different natural habitats, P. crassifolia and P. coronopus both halophytes and P. major, considered as salt-sensitive since it is never found in natural saline habitats. Growth inhibition measurements in controlled salt treatments indicated, however, that P. major is quite resistant to salt stress, although less than its halophytic congeners. The contents of monovalent ions and specific osmolytes were determined in plant leaves after four-week salt treatments. Salt-treated plants of the three taxa accumulated Na+ and Cl- in response to increasing external NaCl concentrations, to a lesser extent in P. major than in the halophytes; the latter species also showed higher ion contents in the non-stressed plants. In the halophytes, K+ concentration decreased at moderate salinity levels, to increase again under high salt conditions, whereas in P. major K+ contents were reduced only above 400 mM NaCl. Sorbitol contents augmented in all plants, roughly in parallel with increasing salinity, but the relative increments and the absolute values reached did not differ much in the three taxa. On the contrary, a strong (relative) accumulation of proline in response to high salt concentrations (600 800 mM NaCl) was observed in the halophytes, but not in P. major. These results indicate that the responses to salt stress triggered specifically in the halophytes, and therefore the most relevant for tolerance in the genus Plantago are: a higher efficiency in the transport of toxic ions to the leaves, the capacity to use inorganic ions as osmotica, even under low salinity conditions, and the activation, in response to very high salt concentrations, of proline accumulation and K+ transport to the leaves of the plants.MAH was a recipient of an Erasmus Mundus pre-doctoral scholarship financed by the European Commission (Welcome Consortium). AP acknowledges the Erasmus mobility programme for funding her stay in Valencia to carry out her Master Thesis.Al Hassan, M.; Pacurar, AM.; López Gresa, MP.; Donat Torres, MDP.; Llinares Palacios, JV.; Boscaiu Neagu, MT.; Vicente Meana, Ó. (2016). Effects of Salt Stress on Three Ecologically Distinct Plantago Species. PLoS ONE. 11(8):1-21. doi:10.1371/journal.pone.0160236S12111

Experimental investigation of segmented SOECs: Locally-resolved impedance and degradation characteristics

Abstract High temperature solid oxide electrolysis cells (SOEC) provide an innovative solution for direct conversion of steam and electricity to hydrogen with the addi- tional capability of adding CO2 to produce syngas. However, specific operating conditions can have a negative impact on the performance and lifetime of SOECs. In this context, the distributions of operational parameters such as gas species, temperature and current density within the cell structure influence local transport processes and reaction kinetics and can lead to locally different electrochemical potentials and thus degradation phenomena. This study focuses on experimental investigations of steam-electrode supported SOECs with segmented air electrodes with the main objective to measure EIS and thus identify locally-resolved impedance and degradation characteristics caused by different operating conditions in steam and co-electrolysis mode. Thereby, significant correlations between operating condi- tions, local effects, electrode processes and degradation mechanisms were observed and analyzed in detail using EIS,DRT and SEM.Keywords:Solid Oxide Electrolysis Cell (SOEC), Segmented, Locally-resolved, Electrochemical Analayis, Distribution of Relaxation Times (DR

Experimental identification of the impact of direct internal and external methane reforming on SOFC by detailed online monitoring and supporting measurements

Solid Oxide Fuel Cells (SOFCs) are able to use biogas or natural gas with its main compound methane as fuel but utilization of methane bears risks which can lead to early performance loss. Application of a suitable type of methane reforming as well as online monitoring tools and a holistic knowledge about possible degradation mechanisms can limit degradation rates. Here, we compare direct internal reforming and external methane reforming on a large planar SOFC with an active area of at different operating temperatures and methane flow rates. To do so, the measured temperature distribution, applied electrochemical impedance spectroscopy and its advanced tool distribution of relaxation times (DRT) as well as results from post mortem microscopic analysis are used. We observed that the ohmic resistance and high frequency peaks in the DRT spectra seem to be influenced not only by the average cell temperature but also by direct internal reforming (DIR) conditions. Furthermore, we observed that high temperature gradients induced by DIR could lead to or accelerate damages of the cells structure and the sealing. The results presented in this work are useful to control or manage safe SOFC operation with C containing fuels for real world SOFC applications

Performance assessment of industrial-sized solid oxide cells operated in a reversible mode: Detailed numerical and experimental study

Reversible solid oxide cells (rSOCs) present a unique possibility in comparison to other available technologies to generate electricity, heat and valuable fuels in one system, in a highly-efficient manner. The major issue hindering their commercialization are system reliability and durability. A detailed understanding of the processes and mechanisms that occur within rSOCs of industrial-size, is of critical importance for addressing this challenge. This study provides in-depth insight into behavior of large planar rSOCs based on a comprehensive experimental and numerical study. All the numerical data obtained are validated with the in-house made cells and experiments. The sensitivity analysis, which covers a wide range of operating conditions relevant for industrial-sized systems, such as varying operating temperature, H2/H2O-ratio, operating current etc., provides very good accordance of the cell performance measured and simulated. It reveals that lowering fuel volume and thus causing fuel starvation has more pronounced effect in an electrolysis mode, which is visible in both the low-frequency and the middle-frequency range. Moreover, both co- and counter-flow are appropriate for the reversible operation. However, more uniform current density distribution is achievable for the counter-flow, which is of crucial importance for the real system design. The most accurate performance prediction can be achieved when dividing the cell into 15 segments. Slightly lower accuracy is reached by logarithmic averaging the fuel compositions, thus reducing the calculation time required. A computationally- and time-efficient model with very precise performance prediction for industrial-sized cells is thus developed and validated

Spermidine affects the transcriptome responses to high temperature stress in ripening tomato fruit* #

Objective: High temperature adversely affects quality and yield of tomato fruit. Polyamine can alleviate heat injury in plants. This study is aimed to investigate the effects of polyamine and high temperature on transcriptional profiles in ripening tomato fruit. Methods: An Affymetrix tomato microarray was used to evaluate changes in gene expression in response to exogenous spermidine (Spd, 1 mmol/L) and high temperature (33/27 °C) treatments in tomato fruits at mature green stage. Results: Of the 10 101 tomato probe sets represented on the array, 127 loci were differentially expressed in high temperature-treated fruits, compared with those under normal conditions, functionally characterized by their involvement in signal transduction, defense responses, oxidation reduction, and hormone responses. However, only 34 genes were up-regulated in Spd-treated fruits as compared with non-treated fruits, which were involved in primary metabolism, signal transduction, hormone responses, transcription factors, and stress responses. Meanwhile, 55 genes involved in energy metabolism, cell wall metabolism, and photosynthesis were down-regulated in Spd-treated fruits. Conclusions: Our results demonstrated that Spd might play an important role in regulation of tomato fruit response to high temperature during ripening stage