Potential for nocturnal satellite detection of suspended matter concentrations in coastal waters using a panchromatic band: a feasibility study based on VIIRS (NASA/NOAA) spectral and radiometric specifications.

Satellite remote sensing of coastal waters is important for understanding the functioning of these complex ecosystems. High satellite revisit frequency is required to permit a relevant monitoring of the strong dynamical processes involved in such areas, for example rivers discharge or tidal currents. One key parameter that is derived from satellite data is the suspended particulate matter (SPM) concentration. Knowledge of the variability of SPM could be used by sediment transport models for providing accurate predictions. Most of the current satellites that are dedicated to ocean color observations have a sun-synchronous orbit that performs a single daytime observation. The Visible Infrared Imaging Radiometer Suite (VIIRS) ocean color sensor (NASA/NOAA) is the only one that is equipped with a panchromatic spectral band, so-called Day-Night Band, which is able to measure extremely low level signals, typically of the order of magnitude of 10-5 W m-2 sr-1µm-1. The objective of this paper is to investigate the potential of the panchromatic and radiometric specifications of the VIIRS sensor to detect SPM concentrations from nighttime satellite observations. Realistic radiative transfer simulations are performed to quantitatively determine the amplitude of the top of atmosphere radiances under various conditions such as various moon incident illuminations, observation geometries, atmospheric and oceanic turbidities. The simulations are compared with the minimum detectable radiance as specified for the VIIRS sensor. The results show that the detection of SPM is systematically feasible, including in clear waters, for any observation geometries in the case of a full moon illumination. The sensitivity of the results to the lunar phase (i.e., out of the full moon conditions), which is one of the originalities of the study, shows that the detection should also be feasible for a significant number of nights over the entire lunar cycle, typically from 5 to 15 nights depending on the water turbidity. Therefore, nighttime ocean color panchromatic measurements performed using a VIIRS-like sensor are a highly promising approach, especially if it is combined with daytime observations, for improving the monitoring of ocean dynamics.

Structure and electrochemical properties of carbon nanostructures derived from nickel(II) and iron(II) phthalocyanines.

Mesoporous carbons containing up to 3.6 at.% N and 4.4 at.% O and exhibiting graphitic character have been prepared from Ni(II) and Fe(II) phthalocyanines by direct pyrolysis or by HTC + pyrolysis, and subsequently applied as supercapacitor materials. No mesoporous templates or doping post-treatments were used, and the catalytic effect of Ni(II) and Fe(II), naturally present in the precursor molecules, allowed obtaining graphitic carbons at temperatures ≤ 900 °C. Metals were encapsulated in the core of onion-like structures with no contact with the electrolyte, so that electrodes were prevented from degradation during device operation. The materials exhibited high rate capabilities up to 1 V s-1, higher interfacial capacitances than a wide variety of materials possessing higher surface areas, and high capacitance retentions up to 99% at 5 A g-1 current density throughout 10 000 charge-discharge cycles. The electrochemical performances of the phthalocyanine-derived carbons are due to their graphitic character and to the pseudocapacitance contribution of the surface groups through Faradaic reactions. This work opens a new way to obtain carbon materials from a great family of metal phthalocyanines, since the central metal and the radicals of the latter can be varied to tune the carbon properties for specific applications.

Nanostructured tin oxide materials for the sub-ppm detection of indoor formaldehyde pollution.

Interesting sensing performances of indoor formaldehyde pollution were obtained when small amounts of zinc were introduced in tin oxides. Nanostructured Sn oxide-based porous materials doped with Zn or not, were synthesized using hydrothermal routes. The physicochemical properties of the as-prepared metal-oxide materials were characterized using nitrogen adsorption, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Gas sensors were prepared using the aforementioned tin oxide materials and they exhibited a high sensitivity to formaldehyde at 230 °C, as well as a good repeatability over the time. Their limit of formaldehyde detection was as low as 8 ppb in dry air and 50 ppb in air with 60% RH at 25 °C. These results were much better that those reported in the open literature and they were attributed to both higher area BET, around 180 m2/g, and smaller crystallite size, 3.1 nm.

Structural Characterisation and Chemical Stability of Commercial Fibrous Carbons in Molten Lithium Salts.

The growing trend towards sustainable energy production, while intermittent, can meet all the criteria of energy demand through the use and development of high-performance thermal energy storage (TES). In this context, high-temperature hybrid TES systems, based upon the combination of fibrous carbon hosts and peritectic phase change materials (PCMs), are seen as promising solutions. One of the main conditions for the operational viability of hybrid TES is the chemical inertness between the components of the system. Thus, the chemical stability and compatibility of several commercial carbon felts (CFs) and molten lithium salts are discussed in the present study. Commercial CFs were characterised by elemental analysis, X-ray diffraction (XRD) and Raman spectroscopy before being tested in molten lithium salts: LiOH, LiBr, and the LiOH/LiBr peritectic mixture defined as our PCM of interest. The chemical stability was evaluated by gravimetry, gas adsorption and scanning electron microscopy (SEM). Among the studied CFs, the materials with the highest carbon purity and the most graphitic structure showed improved stability in contact with molten lithium salts, even under the most severe test conditions (750 °C). The application of the Arrhenius law allowed calculating the activation energy (in the range of 116 to 165 kJ mol-1), and estimating the potential stability of CFs at actual application temperatures. These results confirmed the applicability of CFs as porous hosts for stabilising peritectic PCMs based on molten lithium salts.

A Promiscuous CYP706A3 Reduces Terpene Volatile Emission from Arabidopsis Flowers, Affecting Florivores and the Floral Microbiome.

Flowers are essential but vulnerable plant organs, exposed to pollinators and florivores; however, flower chemical defenses are rarely investigated. We show here that two clustered terpene synthase and cytochrome P450 encoding genes (TPS11 and CYP706A3) on chromosome 5 of Arabidopsis (Arabidopsis thaliana) are tightly coexpressed in floral tissues, upon anthesis and during floral bud development. TPS11 was previously reported to generate a blend of sesquiterpenes. By heterologous coexpression of TPS11 and CYP706A3 in yeast (Saccharomyces cerevisiae) and Nicotiana benthamiana, we demonstrate that CYP706A3 is active on TPS11 products and also further oxidizes its own primary oxidation products. Analysis of headspace and soluble metabolites in cyp706a3 and 35S:CYP706A3 mutants indicate that CYP706A3-mediated metabolism largely suppresses sesquiterpene and most monoterpene emissions from opening flowers, and generates terpene oxides that are retained in floral tissues. In flower buds, the combined expression of TPS11 and CYP706A3 also suppresses volatile emissions and generates soluble sesquiterpene oxides. Florivory assays with the Brassicaceae specialist Plutella xylostella demonstrate that insect larvae avoid feeding on buds expressing CYP706A3 and accumulating terpene oxides. Composition of the floral microbiome appears also to be modulated by CYP706A3 expression. TPS11 and CYP706A3 simultaneously evolved within Brassicaceae and form the most versatile functional gene cluster described in higher plants so far.plantcell;31/12/2947/FX1F1fx1.

Metal Immobilization on Wood-Derived Biochars: Distribution and Reactivity of Carbonate Phases.

Metals can be immobilized on biochars by precipitation with carbonate. The distribution of metal-carbonate phases at the surface of biochars and the conditions of their formation, however, are unknown. Electron microscopy and X-photon spectroscopy were used to characterize carbonate phases in various morphological groups of particles of a wood-derived biochar, both before and after a metal-sorption experiment. Our results showed that the distribution of metals at the surface of biochar particles depended on the corresponding wood tissues and the presence of carbonate phases. Metals were particularly concentrated (i) within calcium carbonate crystals in bark-derived particles, which originated from calcium oxalate crystals formed prior to pyrolysis, and (ii) as new phases formed by the reprecipitation of carbonate on specific tissues of biochar. The formation of biochar carbonate phases and their redistribution by dissolution-precipitation mechanisms may primarily control the localization of metals on biochar particles and the durability of metals immobilization.

Nonlinear Unmixing of Hyperspectral Data With Vector-Valued Kernel Functions.

This paper presents a kernel-based nonlinear mixing model for hyperspectral data, where the nonlinear function belongs to a Hilbert space of vector valued functions. The proposed model extends the existing ones by accounting for band-dependent and neighboring nonlinear contributions. The key idea is to work under the assumption that nonlinear contributions are dominant in some parts of the spectrum, while they are less pronounced in other parts. In addition to this, we motivate the need for taking into account nonlinear contributions originating from the ground covers of neighboring pixels by practical considerations, precisely the adjacency effect. The relevance of the proposed model is that the nonlinear function is associated with a matrix valued kernel that allows to jointly model a wide range of nonlinearities and includes prior information regarding band dependences. Furthermore, the choice of the nonlinear function input allows to incorporate neighboring effects. The optimization problem is strictly convex and the corresponding iterative algorithm is based on the alternating direction method of multipliers. Finally, experiments conducted using synthetic and real data demonstrate the effectiveness of the proposed approach.

Flavour compounds in tomato fruits: identification of loci and potential pathways affecting volatile composition.

The unique flavour of a tomato fruit is the sum of a complex interaction among sugars, acids, and a large set of volatile compounds. While it is generally acknowledged that the flavour of commercially produced tomatoes is inferior, the biochemical and genetic complexity of the trait has made breeding for improved flavour extremely difficult. The volatiles, in particular, present a major challenge for flavour improvement, being generated from a diverse set of lipid, amino acid, and carotenoid precursors. Very few genes controlling their biosynthesis have been identified. New quantitative trait loci (QTLs) that affect the volatile emissions of red-ripe fruits are described here. A population of introgression lines derived from a cross between the cultivated tomato Solanum lycopersicum and its wild relative, S. habrochaites, was characterized over multiple seasons and locations. A total of 30 QTLs affecting the emission of one or more volatiles were mapped. The data from this mapping project, combined with previously collected data on an IL population derived from a cross between S. lycopersicum and S. pennellii populations, were used to construct a correlational database. A metabolite tree derived from these data provides new insights into the pathways for the synthesis of several of these volatiles. One QTL is a novel locus affecting fruit carotenoid content on chromosome 2. Volatile emissions from this and other lines indicate that the linear and cyclic apocarotenoid volatiles are probably derived from separate carotenoid pools.

Production of a recombinant carotenoid cleavage dioxygenase from grape and enzyme assay in water-miscible organic solvents.

A recombinant carotenoid cleavage dioxygenase from Vitis vinifera L. was produced by Escherichia coli as a fusion with the glutathione-S-transferase (GST) protein under different bacterial growth conditions. The enzyme production was monitored by a GST assay. Addition of Triton X-100 prior to bacterial cell disruption doubled the release of soluble protein. A simple spectrophotometric enzyme assay was developed to measure carotenoid cleavage activity using lutein as substrate. Enzyme activity showed a 26-fold increase with the addition of 10% (v/v) acetone in the reaction mixture.

A carotenoid cleavage dioxygenase from Vitis vinifera L.: functional characterization and expression during grape berry development in relation to C13-norisoprenoid accumulation.

A potential Carotenoid Cleavage Dioxygenase (CCD) gene was identified among a Vitis vinifera L. EST collection and a full-length cDNA (VvCCD1) was isolated. Recombinant expression of VvCCD1 confirmed that the gene encoded a functional CCD. Experimental evidence was obtained that VvCCD1 cleaves zeaxanthin symmetrically yielding 3-hydroxy-beta-ionone, a C(13)-norisoprenoidic compound, and a C(14)-dialdehyde. Expression of the gene was studied by real-time PCR at different developmental stages of grape berries from Muscat of Alexandria and Shiraz cultivars. A significant induction of the gene expression approaching véraison was observed in both cultivars. In parallel, the C(13)-norisoprenoid level increased from véraison to maturity in both cultivars.