Long-term mannitol-induced osmotic stress leads to stomatal closure, carbohydrate accumulation and changes in leaf elasticity in Phaselous vulgaris leaves

The effect of long-term osmotic stress was investigated in leaves of two common bean lines, with contrasting tolerance: Flamingo (tolerant) and coco blanc (sensitive). Water relations, organic solute, ion accumulation and amino acids content as well as osmotic adjustment (OA) were studied during an extended exposure to osmotic stress. Osmotic stress was applied by means of 50 mM mannitol for 15 days. At the end of the stress period, both osmotic potential at full turgor (Ψ100) and at turgor loss point (Ψ0) decreased significantly in stressed plants compared with the control. The decrease being greater in the sensitive line, showed a greater OA compared with flamingo. Sugars contents increased in stressed plants and seem to be the major components of osmotic adjustment in stressed common bean leaves. The increase was more marked in coco blanc. Osmotic stress tolerance could thus not be associated with higher OA. The possible role of decreased leaf cell elasticity (εmax) is discussed in relation to osmotic stress tolerance in this species.Key words: Common bean, carbohydrate accumulation, growth, osmotic stress, osmotic adjustment, P-V curve, water relations

Effect of hydration on the dielectric properties of C-S-H gel

9 páginas, 7 figuras, 1 tabla.-- Trabajo presentado a la "Gordon Research Conference: Water & Aqueous Solutions" celebrada en EE.UU. del 8 al 13 de agosto de 2010.The behavior of water dynamics confined in hydrated calcium silicate hydrate (C-S-H) gel has been investigated using broadband dielectric spectroscopy (BDS; 10−2–106 Hz) in the low-temperature range (110–250 K). Different water contents in C-S-H gel were explored (from 6 to 15 wt%) where water remains amorphous for all the studied temperatures. Three relaxation processes were found by BDS (labeled 1 to 3 from the fastest to the slowest), two of them reported here for the first time. We show that a strong change in the dielectric relaxation of C-S-H gel occurs with increasing hydration, especially at a hydration level in which a monolayer of water around the basic units of cement materials is predicted by different structural models. Below this hydration level both processes 2 and 3 have an Arrhenius temperature dependence. However, at higher hydration level, a non-Arrhenius behavior temperature dependence for process 3 over the whole accessible temperature range and, a crossover from low-temperature Arrhenius to high-temperature non-Arrhenius behavior for process 2 are observed. Characteristics of these processes will be discussed in this work.Authors gratefully acknowledge the support of Consolider (CSD2006-00053) and Etortek program. S.C. gratefully acknowledge the support of CSIC (200860I021) and S.C. S.A-I, A.A and J.C. gratefully acknowledge the support of the DYNACOP program and the Basque Government, and project IT-436-07 and the Spanish Ministry of Education, project MAT-22007-63681.Peer reviewe

Effect of hydration on the dielectric properties of C-S-H gel

9 páginas, 7 figuras, 1 tabla.-- Trabajo presentado a la "Gordon Research Conference: Water & Aqueous Solutions" celebrada en EE.UU. del 8 al 13 de agosto de 2010.The behavior of water dynamics confined in hydrated calcium silicate hydrate (C-S-H) gel has been investigated using broadband dielectric spectroscopy (BDS; 10−2–106 Hz) in the low-temperature range (110–250 K). Different water contents in C-S-H gel were explored (from 6 to 15 wt%) where water remains amorphous for all the studied temperatures. Three relaxation processes were found by BDS (labeled 1 to 3 from the fastest to the slowest), two of them reported here for the first time. We show that a strong change in the dielectric relaxation of C-S-H gel occurs with increasing hydration, especially at a hydration level in which a monolayer of water around the basic units of cement materials is predicted by different structural models. Below this hydration level both processes 2 and 3 have an Arrhenius temperature dependence. However, at higher hydration level, a non-Arrhenius behavior temperature dependence for process 3 over the whole accessible temperature range and, a crossover from low-temperature Arrhenius to high-temperature non-Arrhenius behavior for process 2 are observed. Characteristics of these processes will be discussed in this work.Authors gratefully acknowledge the support of Consolider (CSD2006-00053) and Etortek program. S.C. gratefully acknowledge the support of CSIC (200860I021) and S.C. S.A-I, A.A and J.C. gratefully acknowledge the support of the DYNACOP program and the Basque Government, and project IT-436-07 and the Spanish Ministry of Education, project MAT-22007-63681.Peer reviewe

Radiative Cooling Properties of Portlandite and Tobermorite: Two Cementitious Minerals of Great Relevance in Concrete Science and Technology

Although concrete and cement-based materials are the most engineered materials employed by mankind, their potential for use in daytime radiative cooling applications has yet to be fully explored. Due to its complex structure, which is composed of multiple phases and textural details, fine-tuning of concrete is impossible without first analyzing its most important ingredients. Here, the radiative cooling properties of Portlandite (Ca(OH)2) and Tobermorite (Ca5Si6O16(OH)2·4H2O) are studied due to their crucial relevance in cement and concrete science and technology. Our findings demonstrate that, in contrast to concrete (which is a strong infrared emitter but a poor sun reflector), both Portlandite and Tobermorite exhibit good radiative cooling capabilities. These results provide solid evidence that, with the correct optimization of composition and porosity, concrete can be transformed into a material suitable for daytime radiative cooling

Wer ist heute 'Ehrenmann' und 'Ehrenfrau'? Ethische und jugendkulturelle Aspekte des deutschen Jugendworts des Jahres

Eine Jury des deutschen Langenscheidt-Verlags wählt jedes Jahr das sogenannte 'Jugendwort des Jahres'. 2018 fiel diese Wahl auf 'Ehrenmann' bzw. 'Ehrenfrau' im Sinne von 'jemand, der etwas (Besonderes) für einen tut'. In der Folge fand jedoch weder eine öffentliche Auseinandersetzung über die Herkunft des Begriffs statt noch darüber, was Ehre für Jugendliche heute bedeutet. Der Artikel möchte daher zunächst darstellen, was Ehre ist und welche soziale Funktion sie erfüllt, und anschließend die besondere Bedeutung von Ehre für Jugendliche in Migrationssituationen reflektieren. Schließlich folgen eine pop- und jugendkulturelle Analyse der Herkunft und Verwendung des Ausdrucks 'Ehrenmann' (und 'Ehrenfrau') sowie eine abschließende kritische Reflexion der Jurywahl.Every year, a jury of the German Langenscheidt-Verlag chooses the so-called 'youth expression of the year' (Jugendwort des Jahres). In 2018, this choice fell on 'man/woman of honour' (Ehrenmann/Ehrenfrau), in a sense of ‚someone doing something (special) for somebody‘. Interestingly, no public discourse followed to examine the origin of this unusual expression or the meaning of 'honour' for today's youth. The article, therefore, aims to outline what honour is and which social functions it fulfils, and then to reflect the particular significance of honour for adolescents with a migrant background. This is followed by a pop- and youth-cultural analysis of the origin and use of the expression 'man of honour' as well as a concluding critical reflection of the jury's choice

Absolute quantification of Medicago truncatula sucrose synthase isoforms and N-metabolism enzymes in symbiotic root nodules and the detection of novel nodule phosphoproteins by mass spectrometry

Mass spectrometry (MS) has become increasingly important for tissue specific protein quantification at the isoform level, as well as for the analysis of protein post-translational regulation mechanisms and turnover rates. Thanks to the development of high accuracy mass spectrometers, peptide sequencing without prior knowledge of the amino acid sequence—de novo sequencing—can be performed. In this work, absolute quantification of a set of key enzymes involved in carbon and nitrogen metabolism in Medicago truncatula ‘Jemalong A17’ root nodules is presented. Among them, sucrose synthase (SuSy; EC 2.4.1.13), one of the central enzymes in sucrose cleavage in root nodules, has been further characterized and the relative phosphorylation state of the three most abundant isoforms has been quantified. De novo sequencing provided sequence information of a so far unidentified peptide, most probably belonging to SuSy2, the second most abundant isoform in M. truncatula root nodules. TiO2-phosphopeptide enrichment led to the identification of not only a phosphorylation site at Ser11 in SuSy1, but also of several novel phosphorylation sites present in other root nodule proteins such as alkaline invertase (AI; EC 3.2.1.26) and an RNA-binding protein

Session 17 Ecophysiology

n/

Chain Dynamics on Crossing the Glass Transition: Nonequilibrium Effects and Recovery of the Temperature Dependence of the Structural Relaxation

In this paper we report thermally stimulated depolarization current results on the chain and segmental dynamics of two monodisperse polyisoprenes accessing both dynamics at ultralow frequency range and exploring the relationship between segmental and chain time scales when crossing the glass transition. In this range, we have recorded experimental evidence of nonequilibrium effects on the slowest chain mode dynamics. The nonequilibrium effects seem to occur simultaneously for both chain and α-relaxation. Moreover, detailed analysis strongly indicates the recovery of an even T-dependence for the chain and α-relaxation dynamics on crossing glass transition and in the glassy state. The obtained results can be understood taking into account the different temperature dependences of the length scales involved in the segmental and chain relaxations

Dynamics in poly(n-alkyl methacrylates): A neutron scattering, calorimetric and dielectric study

Combining neutron diffraction, neutron spin echo, differential scanning calorimetry, and dielectric spectroscopy, we have investigated the structure and dynamics of poly(n-butyl methacrylate) (PBMA) and poly(n-hexyl methacrylate) (PHMA). Signatures of the occurrence of a glass transition associated with the freezing of the intermolecular correlations within alkyl nanodomains are present in the structural data. Exploiting isotopic labeling, neutron scattering has revealed collective dynamics at the main-chain and side-group levels for both polymers and the self-motions of hydrogen atoms in the side groups of PHMA, adding valuable microscopic information to comprehensive relaxation maps and putting the relaxation results into a perspective. Moreover, we find exotic dynamical behavior for the side groups, characterized by extremely stretched (nearly logarithmic-like) decays of the correlation functions. For PHMA, a complete dynamical decoupling of side-group dynamics from the main-chain motions is found. The side groups of this polymer show an extremely "strong" temperature dependence of the structural relaxation time and much faster characteristic times for self than collective motions. The analogies found between the self-motions of the side-group H atoms in PHMA and the gamma-relaxation process in semicrystalline polyethylene (PE) strengthen the picture of confined PE-like dynamics within alkyl nanodomains. We discuss possible origins for the observed phenomenology