First examples of pyran based colorants as sensitizing agents of p-Type Dye-Sensitized solar cells

Three different pyran based dyes were synthesized and tested for the first time as photosensitizers of NiO based p-type dye-sensitized solar cells (p-DSSC). The molecules feature a similar molecular structure and are based on a pyran core that is functionalized with electron acceptor groups of different strength and is symmetrically coupled to phenothiazine donor branches. Optical properties of the dyes are deeply influenced by the nature of the electron-acceptor group, so that the overall absorption of the three dyes covers the most of the visible spectrum. The properties of devices based on the NiO electrodes sensitized with the investigated dyes were evaluated under simulated solar radiation: the larger short circuit current density exceeded 1mA/cm2 and power conversion efficiency as high as 0.04% could be recorded. The performances of the fabricated p-DSSC have been compared to a reference cell sensitized with P1, a high level benchmark, which afforded a photoelectrochemical activity similar to the best example of our pyran sensitized devices (1.19 mA/cm2 and 0.049%)

Detecting Phase Transitions through Nonequilibrium Work Fluctuations

We show how averages of exponential functions of path dependent quantities, such as those of Work Fluctuation Theorems, detect phase transitions in deterministic and stochastic systems. State space truncation -- the restriction of the observations to a subset of state space with prescribed probability -- is introduced to obtain that result. Two stochastic processes undergoing first-order phase transitions are analyzed both analytically and numerically: the Ehrenfest urn model and the 2D Ising model subject to a magnetic field. In presence of phase transitions, we prove that even minimal state space truncation makes averages of exponentials of path dependent variables sensibly deviate from full state space values. Specifically, in the case of discontinuous phase transitions, this approach is strikingly effective in locating the critical transition value of the control parameter. As this approach works even with variables different from those of fluctuation theorems, it provides a new recipe to identify order parameters in the study of nonequilibrium phase transitions, profiting from the often incomplete statistics that are available

Finite reservoirs and irreversibility corrections to Hamiltonian systems statistics

We consider several Hamiltonian systems perturbed by external agents, that preserve their Hamiltonian structure. We investigate the corrections to the canonical statistics resulting from coupling such systems with possibly large but finite reservoirs, and from the onset of processes breaking the time reversal symmetry. We analyze exactly solvable oscillators systems, and perform simulations of relatively more complex ones. This indicates that the standard statistical mechanical formalism needs to be adjusted, in the ever more investigated nano-scale science and technology. In particular, the hypothesis that heat reservoirs be considered infinite and be described by the classical ensembles is found to be critical when exponential quantities are considered, since the large size limit may not coincide with the infinite size canonical result. Furthermore, process-dependent emergent irreversibility affects ensemble averages, effectively frustrating, on a statistical level, the time reversal invariance of Hamiltonian dynamics, that is used to obtain numerous results

“L’integrazione europea nei Balcani occidentali: il ruolo delle organizzazioni dei lavoratori per favorire il dialogo sociale”

SEMINARIO INTERNAZIONALE DI STUDI EUROPEIBUCAREST - ROMANIA5 – 6 Febbraio 202

Synchronous dynamics in the presence of short-term plasticity

We investigate the occurrence of quasisynchronous events in a random network of excitatory leaky integrate-and-fire neurons equipped with short-term plasticity. The dynamics is analyzed by monitoring both the evolution of global synaptic variables and, on a microscopic ground, the interspike intervals of the individual neurons. We find that quasisynchronous events are the result of a mixture of synchronized and unsynchronized motion, analogously to the emergence of synchronization in the Kuramoto model. In the present context, disorder is due to the random structure of the network and thereby vanishes for a diverging network size $N$ (i.e., in the thermodynamic limit), when statistical fluctuations become negligible. Remarkably, the fraction of asynchronous neurons remains strictly larger than zero for arbitrarily large $N$. This is due to the presence of a robust homoclinic cycle in the self-generated synchronous dynamics. The nontrivial large-$N$ behavior is confirmed by the anomalous scaling of the maximum Lyapunov exponent, which is strictly positive in a finite network and decreases as {N}^{\ensuremath{-}0.27}. Finally, we have checked the robustness of this dynamical phase with respect to the addition of noise, applied to either the reset potential or the leaky current

Consecutive blood lactate assessment in HIV-infected children: correlation with therapy and clinical characteristics

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Increase of spinach growth through the use of larger plug cell volume and an exogenous BAP spray

In spinach, transplanting has replaced direct seeding but small containers may cause root restriction effects that would be decreased post-transplant yield. Although a single hormonal regulator (BAP) spray is effective in overcoming root restriction, the mechanisms involved are unknown. The objective of this work was to analyze yield changes by the use of different plug cell volumes and BAP as foliar spray. Our results showed that the use of large plug cell volumes and BAP sprays at the pre-transplant stage increased plant productivity, through an increase in the relative growth rate (RGR) or the rate of leaf area expansion (RLAE). We found a close direct relationship between RGR and net assimilation rate (NAR) but an inverse relationship between RGR and leaf area ratio (LAR). In addition, we found that NAR significantly increased as leaf thickness, intercellular spaces and stomatal density increased. A change in dry weight partitioning toward shoots was found as well.Fil: Di Matteo, Javier Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; ArgentinaFil: Rattin, Jorge Edgardo. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; ArgentinaFil: Di Benedetto, Adalberto Hugo. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Universidad de Buenos Aires. Facultad de Agronomía; Argentin

AFLP analysis to assess genomic stability in Solanum regenerants derived from wild and cultivated species

The cultivated potato as well as its tuber-bearing relatives are considered model plants for cell and tissue culture, and therefore for exploiting the genetic variation induced by in vitro culture. The association between molecular stability and tissue culture in different genetic backgrounds and ploidy levels has already been explored. However, it still remains to be ascertained whether somaclonal variation differs between callus-derived chromosome- doubled and undoubled regenerants. Our research aimed at investigating, through amplified fragment length polymorphism (AFLP) markers, the genetic changes in marker- banding patterns of diploid and tetraploid regenerants obtained from one clone each of Solanum bulbocastanum Dunal and S. cardiophyllum Lindl (both 2n = 2x = 24) and tetraploids from cultivated S. tuberosum L. (2n = 4x = 48). Pairwise comparisons between the banding patterns of regenerants and parents allowed detecting considerable changes associated to in vitro culture both at diploid and tetraploid level. The percentages of polymorphic bands between diploid and tetraploid regenerants were, respectively, 57 and 69% in S. bulbocastanum and 58 and 63% in S. cardiophyllum. On average, the frequencies of lost parental fragments in regenerants were significantly higher than novel bands both in S. bulbocastanum (48 vs. 22%) and S. tuberosum (36 vs. 18%) regenerants. By contrast, in S. cardiophyllum, a similar incidence of the two events was detected (32 vs. 29%). Our results revealed that structural changes after tissue culture process strongly affected the genome of the species studied, but diploid and tetraploids regenerated plants responded equally