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Hybrid perovskites with reduced organic content have brought great interest for solar cells applications. Particularly, adding inorganic cations increase material stability, by providing an adequate tolerance factor. However, these cations lead to lower absorption coefficient than using only organic cations, therefore it is necessary to implement strategies for having films with appropriate thickness and good light absorption properties. In this work, several experiments were performed with ((Cs1-xDMAx)Pb(Br1-xIx)3 perovskite films of different thicknesses, resulting in devices with photovoltaic conversion efficiency (PCE) near 80% of the reference MAPbI3 cell, high purity phase, appropriate morphology, and higher stability. The perovskite successfully maintained integrity for 12 days in air with relative humidity between 30 and 40%, indicating the fulfillment of the study's objectives.

Pervskite solar cells have attracted extensive attention from researchers worldwide due to their rapid development and efficiency. Nevertheless, stability is still an issue that limits the advance of this technology. In this work, we present the fabrication and characterization of two-dimensional perovskites of the Ruddlesden-Popper’s family (A)2(MA)n−1PbnI3n+1 (three different A-site large cations were investigated: A=n-propylammonium, t-Butylammonium or Benzylammonium). The modulation of the large organic cations increased the band gap of the materials and improved moisture and thermal stability, making it possible to fabricate PSCs. Even though the organic interlayers intrinsically reduce the transport properties of the devices and therefore lower currents are obtained in the layered systems, a remarkable efficiency of 10.35% was obtained for (BUA)2(MA)2Pb3I10, with superior stability, and therefore, it was possible to retain 68% of its initial value after 1700 h for devices without encapsulation.

Overexpression of the Arabidopsis thaliana vacuolar H+-pyrophosphatase (AVP1) confers salt tolerance to the salt-sensitive ena1 mutant of Saccharomyces cerevisiae. Suppression of salt sensitivity requires two ion transporters, the Gef1 Cl- channel and the Nhx1 Na+/H+ exchanger. These two proteins colocalize to the prevacuolar compartment of yeast and are thought to be required for optimal acidification of this compartment. Overexpression of AtNHX1, the plant homologue of the yeast Na+/H+ exchanger, suppresses some of the mutant phenotypes of the yeast nhx1 mutant. Moreover, the level of AtNHX1 mRNA in Arabidopsis is increased in the presence of NaCl. The regulation of AtNHX1 by NaCl and the ability of the plant gene to suppress the yeast nhx1 mutant suggest that the mechanism by which cations are detoxified in yeast and plants may be similar

Oscillations in cytosolic free Ca2+ concentration ([Ca2+]cyt) are an important component of Ca2+-based signal transduction pathways. This fact has led us to investigate whether oscillations in [Ca2+]cyt are involved in the response of stomatal guard cells to the plant hormone abscisic acid (ABA). We show that ABA induces oscillations in guard-cell [Ca2+]cyt. The pattern of the oscillations depended on the ABA concentration and correlated with the final stomatal aperture. We examined the mechanism by which ABA generates oscillations in guard-cell [Ca2+]cyt by using 1-(6-([17 beta-3-methoxyestra- 1,3,5(10)-trien-17-yl]amino)hexyl)-1H-pyrrole 2,5-dione (U-73122), an inhibitor of phosphoinositide-specific phospholipase C (PI-PLC)-dependent processes in animals. U-73122 inhibited the hydrolysis of phosphatidylinositol 4,5-bisphosphate by a recombinant PI-PLC, isolated from a guard-cell-enriched cDNA library, in a dose-dependent manner. This result confirms that U-73122 is an inhibitor of plant PI-PLC activity. U-73122 inhibited both ABA-induced oscillations in [Ca2+]cyt and stomatal closure. In contrast, U-73122 did not inhibit external Ca2+-induced oscillations in guard-cell [Ca2+]cyt and stomatal closure. Furthermore, there was no effect of the inactive analogue 1-(6-([17 beta- 3-methoxyestra-1,3,5(10)-trien-17-yl] amino)hexyl)-2,5-pyrrolidinedione on recombinant PI-PLC activity or ABA-induced and external Ca2+-induced oscillations in [Ca2+]cyt and stomatal closure. This lack of effect suggests that the effects of U-73122 in guard cells are the result of inhibition of PI-PLC and not a consequence of nonspecific effects. Taken together, our data suggest a role for PI-PLC in the generation of ABA-induced oscillations in [Ca2+]cyt and point toward the involvement of oscillations in [Ca2+]cyt in the maintenance of stomatal aperture by ABA

Glutathione plays a pivotal role in protecting plants from environmental stresses, oxidative stress, xenobiotics, and some heavy metals. Arabidopsis plants treated with cadmium or copper responded by increasing transcription of the genes for glutathione synthesis, gamma-glutamylcysteine synthetase and glutathione synthetase, as well as glutathione reductase. The response was specific for those metals whose toxicity is thought to be migrated through phytochelatins, and other toxic and nontoxic metals did not alter mRNA levels. Feeding experiments suggested that neither oxidative stress, as results from exposure to H2O2, nor oxidized or reduced glutathione levels were responsible for activating transcription of these genes. Jasmonic acid also activated the same suite of genes, which suggests that it might be involved in the signal transduction pathway for copper and cadmium. Jasmonic acid treatment increased mRNA levels and the capacity for glutathione synthesis but did not alter the glutathione content in unstressed plants, which supports the idea that the glutathione concentration is controlled at multiple levels

Se sintetizaron zeolitas tipo sodalita a partir de silicio y aluminio posconsumo, las cuales se recubrieron con el hidróxido doble laminar (HDL) con una relación molar Mg2+ / Al3+ = 2, que se formaron por el método de coprecipitación a baja saturación. Las propiedades estructurales, morfológicas y texturales de la zeolita, el HDL y el material recubierto se determinaron mediante difracción de rayos X de muestras policristalinas (XRD), microscopía electrónica de barrido (SEM), espectroscopía de resonancia magnética nuclear 27Al (RMN) y medidas texturales. Los sólidos obtenidos se utilizaron para la eliminación de Cu2+, Cl-, NO3- y SO42- desde soluciones acuosas de Cu(NO3)2, CuCl2 y CuSO4, estudiando la capacidad de remoción por espectrometría de fluorescencia de rayos X (XFR) para Cu2+, Cly SO42-, y espectroscopía UV-Vis para el NO3-. Los resultados mostraron que la zeolita tipo sodalita recubierta con HDL fue capaz de hacer la captación simultánea de cationes y aniones como el Cu2+ en 9.26 mmol·g-1, Clen 9.34 mmol·g-1, SO42- en 8.82 mmol·g-1 y NO3- en 14.41 mmol·g-1. Estos resultados muestran que las zeolitas recubiertas con HDL se pueden usar para retener cationes y aniones dañinos para el medio ambiente, y representan una oportunidad para diseñar catalizadores

We quantified soil acidity and exchangeable cations in the forest floor and upper 7.5 cm of mineral soil beneath the canopies of individual trees of six different species in a mixed-species forest in northwestern Connecticut. Soil pH decreased in a sequence starting with sugar maple (Acer saccharum) > white ash (Fraxinus americana) > red maple (Acer rubrum) > beech (Fagus grandifolia) > red oak (Quercus rubra) > eastern hemlock (Tsuga canadensis). The differences among species were largest in the forest floor and the top 7.5 cm of mineral soil. Exchangeable Ca and Mg in the 0-7.5 cm mineral soil layer were significantly higher beneath sugar maple than all other species, with the exception of white ash. There were negligible differences among species in the quantity of exchangeable Ca and Mg in the forest floor. In the 0-7.5 cm mineral soil layer, exchangeable Ca was positively correlated with the content of unweathered Ca in the parent material, but the relationship differed among species. There was a large increase in exchangeable Ca in the soils beneath sugar maple but a negligible increase in the soils beneath hemlock and red maple. Exchangeable Al and Fe were highest beneath hemlock and lowest beneath sugar maple. The differences in pH and exchangeable cations between sugar maple and hemlock are likely due to interspecific differences in the introduction of acidity (e.g., organic acids) and Ca uptake and allocation. Observing an association between tree species and specific soil chemical properties within mixed-species stands implies that changes in the distribution and abundance of tree species alters the spatial and temporal pattern of soil acidity and cation cycling in this forest.

▪ Abstract  New and exciting developments in boron research in the past few years greatly contributed to better understanding of the role of boron in plants. Purification and identification of the first boron-polyol transport molecules resolved much of the controversy about boron phloem mobility. Isolation and characterization of the boron-polysaccharide complex from cell walls provided the first direct evidence for boron crosslinking of pectin polymers. Inhibition and recovery of proton release upon boron withdrawal and restitution in plant culture medium demonstrated boron involvement in membrane processes. Rapid boron-induced changes in membrane function could be attributed to boron-complexing membrane constituents. Boron may affect metabolic pathways by binding apoplastic proteins to cis-hydroxyl groups of cell walls and membranes, and by interfering with manganese-dependent enzymatic reactions. In addition, boron has been implicated in counteracting toxic effects of aluminum on root growth of dicotyledonous plants. Molecular investigations of boron nutrition have been initiated by the discovery of a novel mutant of Arabidopsis thaliana with an altered requirement for boron.

High Al resistance in buckwheat (Fagopyrum esculentum Moench. cv Jianxi) has been suggested to be associated with both internal and external detoxification mechanisms. In this study the characteristics of the external detoxification mechanism, Al-induced secretion of oxalic acid, were investigated. Eleven days of P depletion failed to induce secretion of oxalic acid. Exposure to 50 micromolar LaCl3 also did not induce the secretion of oxalic acid, suggesting that this secretion is a specific response to Al stress. Secretion of oxalic acid was maintained for 8 h by a 3-h pulse treatment with 150 micromolar Al. A nondestructive method was developed to determine the site of the secretion along the root. Oxalic acid was found to be secreted in the region 0 to 10 mm from the root tip. Experiments using excised roots also showed that secretion was located on the root tip. Four kinds of anion-channel inhibitors showed different effects on Al-induced secretion of oxalic acid: 10 micromolar anthracene-9-carboxylic acid and 4,4'-diisothiocyanatostilbene-2,2'-disulfonate had no effect, niflumic acid stimulated the secretion 4-fold, and phenylglyoxal inhibited the secretion by 50%. Root elongation in buckwheat was not inhibited by 25 micromolar Al or 10 micromolar phenylglyoxal alone but was inhibited by 40% in the presence of Al and phenylglyoxal, confirming that secretion of oxalic acid is associated with Al resistance

Iron is an essential nutrient for virtually all organisms. The IRT1 (iron-regulated transporter) gene of the plant Arabidopsis thaliana, encoding a probable Fe(II) transporter, was cloned by functional expression in a yeast strain defective for iron uptake. Yeast expressing IRT1 possess a novel Fe(II) uptake activity that is strongly inhibited by Cd. IRT1 is predicted to be an integral membrane protein with a metal-binding domain. Data base comparisons and Southern blot analysis indicated that IRT1 is a member of a gene family in Arabidopsis. Related sequences were also found in the genomes of rice, yeast, nematodes, and humans. In Arabidopsis, IRT1 is expressed in roots, is induced by iron deficiency, and has altered regulation in plant lines bearing mutations that affect the iron uptake system. These results provide the first molecular insight into iron transport by plants.