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AbstractPhenolic compounds are secondary metabolites involved in plant innate chemical defence against pests and diseases. Their concentration varies depending on plant tissue and also on genetic and environmental factors, e.g. availability of nutrient resources. This study examines specific effects of low (LN) and high (HN) nitrogen supply on organ (root, stem and leaf) growth and accumulation of major phenolics [chlorogenic acid (CGA); rutin; kaempferol rutinoside (KR)] in nine hydroponically grown tomato cultivars. LN limited shoot growth but did not affect root growth, and increased concentrations of each individual phenolic in all organs. The strength of the response was organ‐dependent, roots being more responsive than leaves and stems. Significant differences were observed between genotypes. Nitrogen limitation did not change the phenolic content in shoots, whereas it stimulated accumulation in roots. The results show that this trade‐off between growth and defence in a LN environment can be discussed within the framework of the growth–differentiation balance hypothesis (i.e. GDBH), but highlight the need to integrate all plant organs in future modelling approaches regarding the impact of nitrogen limitation on primary and secondary metabolism.

Abstract. The impact of multiphase reactions involving nitrogen dioxide (NO2) and aromatic compounds was simulated in this study. A mechanism (CAPRAM 2.4, MODAC Mechanism) was applied for the aqueous phase reactions, whereas RACM was applied for the gas phase chemistry. Liquid droplets were considered as monodispersed with a mean radius of 0.1 µm and a liquid content (LC) of 50 µg m-3. The multiphase mechanism has been further extended to the chemistry of aromatics, i.e. reactions involving benzene, toluene, xylene, phenol and cresol have been added. In addition, reaction of NO2 with dissociated hydroxyl substituted aromatic compounds has also been implemented. These reactions proceed through charge exchange leading to nitrite ions and therefore to nitrous acid formation. The strength of this source was explored under urban polluted conditions. It was shown that it may increase gas phase HONO levels under some conditions and that the extent of this effect is strongly pH dependent. Especially under moderate acidic conditions (i.e. pH above 4) this source may represent more than 75% of the total HONO/NO2 - production rate, but this contribution drops down close to zero in acidic droplets (as those often encountered in urban environments).

AbstractSolar fuels offer a promising approach to provide sustainable fuels by harnessing sunlight1,2. Following a decade of advancement, Cu2O photocathodes are capable of delivering a performance comparable to that of photoelectrodes with established photovoltaic materials3–5. However, considerable bulk charge carrier recombination that is poorly understood still limits further advances in performance6. Here we demonstrate performance of Cu2O photocathodes beyond the state-of-the-art by exploiting a new conceptual understanding of carrier recombination and transport in single-crystal Cu2O thin films. Using ambient liquid-phase epitaxy, we present a new method to grow single-crystal Cu2O samples with three crystal orientations. Broadband femtosecond transient reflection spectroscopy measurements were used to quantify anisotropic optoelectronic properties, through which the carrier mobility along the [111] direction was found to be an order of magnitude higher than those along other orientations. Driven by these findings, we developed a polycrystalline Cu2O photocathode with an extraordinarily pure (111) orientation and (111) terminating facets using a simple and low-cost method, which delivers 7 mA cm−2 current density (more than 70% improvement compared to that of state-of-the-art electrodeposited devices) at 0.5 V versus a reversible hydrogen electrode under air mass 1.5 G illumination, and stable operation over at least 120 h.

Abstract The concept of a cTES (for cold Thermal Energy Storage) is experimentally investigated in this paper. It aims at demonstrating its technical relevancy, for arid regions, in improving the efficiency of a dry cooled turbine's condenser. Gain is realized by postponing total or part of the daily heat exhausted from the condenser and shifting the release of the remaining heat during the night-time when the ambient temperatures are lower. The global system consists in a 13 m3 dual-media water/rock thermocline TES connected to a 110 kW heat source and a 100 kW dry cooler. Experiments have been first conducted to validate the thermal storage behavior in well-controlled operations. Then, the thermal storage has been connected in parallel with the dry cooler to highlight the global behavior of the “dry cooler / cTES” cooling system under different operation's conditions. Results confirm that the cTES is able to compensate the performances loss of the dry cooler during daytime in case of high ambient temperature and to evacuate heat and to store cold during nigh-time. The control of the cTES is simple, characterized by continuous and smooth transitions from one mode to another and without discontinuities in performances and operations.

Pyroelectric energy harvesting has the ability to transform wasted heat into useful energy and as such has a potential to create “green” energy from freely available sources such as ambient temperature changes, and contribute to the fight against climate change. Current pyroelectrics applications are limited to low-power electronics, portable systems or tasks needing only very low range of power (μW–mW). Developing further this highly promising technology should ultimately lead to the creation of more powerful, autonomous and self-powered electronic devices that could one day use to recycle currently “lost” thermal energy to power electronic devices in both domestic and industrial settings. To the best of our knowledge, hexagonal phase ZnS (wurtzite ZnS) has not been studied as a possible energy harvesting pyroelectric material despite w-ZnS being isostructural to the well-exploited and widely praised hexagonal ZnO [1]. In addition, the Tc temperature (1020 ˚C for bulk material) is high enough for ZnS that it has the ability to operate at higher temperature that are good match with the working temperature of power plants and automobiles, and hence w-ZnS ceramics should have a potential to be used in pyroelectric harvesters of waste heat coming from those activities [2]. Here we report on the pyroelectric output registered for a wurtzite phase ZnS ceramic fabricated as part of our project. To probe the pyroelectric output for a w-ZnS ceramic a simple device (a “pyro-cell”) was created by evaporating gold electrods on both sides of a ceramic sample, which was mounted on a Cu-metalized rectangular insulating base (vetronite) using silver paint. This device is stable from room temperature up to approximately 180°C. Two different heating and cooling testing set-ups were established: Set-up n°1 used an industrial scale laser, providing a source with fast temperature change, and Set-up n°2 had a standard lab hot plate heating element, providing a much slower temperature change. The characterization required an accurate measurement of the currents of the order of 10-9 A. In addition, using the Pyroelectric Test System (PK‐SPIV17T, State College, PA, USA) with a Keithley 6517 B Picoammeter, we were able to measure the pyroelectric coefficient and monitor its change at different frequencies as a function of temperature from 20 °C up to 150° C, with a heating rate of between 2 and 10 °C/min. Figure 1: Pyroelectric current measurements on an ZnS ceramic sample, using testing set-up n°1. The horizontal axis shows the time (seconds). References [1] Y. Yang, W. Guo, K.C. Pradel, G. Zhu, Y. Zhou, Y. Zhang, Y. Hu, L. Lin, Z. Lin Wang, “Pyroelectric Nanogenerators for Harvesting Thermoelectric Energy”, Nano Lett, 12 (6), 2012, 2833–2838 [2] L.A. Chavez, F.O. Zayas Jimenez, B.R. Wilburn, L.C. Delfin, H. Kim, N. Love, Y. Lin, “Characterization of Thermal Energy Harvesting Using Pyroelectric Ceramics at Elevated Temperatures”, Energy Harvesting and Systems, 5(1-2), 2018, 3–10 This project was also partially supported by the Piano triennale di realizzazione 2019-2021 della ricerca di sistema elettrico nazionale – Progetto 1.3 Materiali di frontiera per usi energetici (C.U.P. code: I34I19005780001).